TY - JOUR A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed A. A1 - Böhning, Martin A1 - Frick, B. A1 - Apple, M. A1 - Mole, R. A. A1 - De Souza, N. R. A1 - Zorn, R. A1 - Schönhals, Andreas T1 - Confined Segmental Diffusion in Nanophase Separated Janus Polynorbornenes as Investigated by Quasielastic Neutron Scattering N2 - A combination of neutron time-of-flight and neutron backscattering spectroscopy was used to investigate the molecular dynamics of Janus polynorbornenes (Janus poly(tricyclononenes)) on a microscopic level. These Janus polynorbornenes, denoted as PTCNSiOR, have a semirigid backbone with −Si(OR)3 side groups attached to it. R represents the length of the alkyl side chain. Here side chain lengths of R = 3 (propyl) and R = 8 (octyl) were considered. It is worth mentioning that these polymers have some potential as active layers in gas separation membranes, especially for the separation of higher hydrocarbons. The combination of time-of-flight and backscattering will ensure a reasonably broad time window for analysis where the incoherent intermediate scattering function SInc(q,t) is considered. Previously, it was shown by X-ray investigations that the system undergoes a nanophase separation into alkyl side chain-rich domains surrounded by a backbone-rich matrix. For PTCNSiOPr (R = 3), the alkyl side-chain-rich domains are truly isolated in the backbone-rich matrix, whereas for PTCNSiOOc (R = 8) these domains percolate through the matrix. Further, it was also previously shown that the alkyl side-chain-rich domains undergo a glass transition. The advantage of neutron scattering experiments discussed here is that besides temporal also spatial information is obtained which will allow conclusions to be drawn about the type of molecular fluctuations. At the lowest measured temperature, the decay in Sinc(q,t) is due to the methyl group rotation. The methyl group dynamics is analyzed in terms of a modified jump-diffusion in a 3-fold potential and yields to a reasonable fraction of hydrogens which contribute to the methyl group rotation. At higher temperatures, the decay in SInc(q,t) is due to both the methyl group rotation and the segmental dynamics in the alkyl side-chain-rich domains. The segmental diffusion is modeled by a sublinear diffusion. For the analysis of the scattering function SInc(q,t) of PTCNSiOPr an elastic scattering due to the immobilized backbone-rich matrix must be taken into account. The analysis reveals that the segmental dynamics is confined by the finite size of alkyl chain-rich domains and that it is intrinsically heterogeneous in nature. Both effects are more pronounced for PTCNSiOPr in comparison to those of PTCNSiOOc. KW - Polynorbornene KW - Quasielastic Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608712 DO - https://doi.org/10.1021/acs.macromol.4c01045 SP - 1 EP - 14 PB - ACS Publications AN - OPUS4-60871 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Wachtendorf, Volker A1 - Böhning, Martin T1 - Characteristics of environmental stress cracking of PE-HD induced by biodiesel and diesel fuels N2 - In the context of the increasing effect of carbon dioxide emissions on the global climate biodiesel produced from renewable sources has emerged as a promising contender replacing fossil fuels, especially in long-range transport vehicles, using existing engines and infrastructure. High-density polyethylene is one of the prevailing materials for pipe and container applications for storage and transport of such fuels, both, from fossil and renewable resources. The contact with the respective fuels raises questions concerning material compatibility as biodiesel exhibits significant differences compared to conventional diesel fuel affecting its sorption and plasticization behavior in polyethylene. In this study, its behavior with respect to environmental stress cracking, considered one of the most frequent damage mechanisms leading to failure of polymer parts and packaging, was evaluated using the well-established Full Notch Creep Test. This approach allows for a detailed fracture surface analysis using imaging techniques, such as optical and laser scanning microscopy, as well as infrared spectroscopy. Comparing the environmental stress cracking behavior in standard surfactant solutions with that in biodiesel and diesel, respective crack propagation rates, showing different levels of acceleration, were determined and details of the underlying mechanisms could be revealed. Furthermore, the specific infrared absorption of the biodiesel’s ester functionality allows its semi-quantitative determination on the fracture surface of the tested specimens after failure. Thus, a preferred uptake of sorptive fluids in the fracture zone due to local morphological changes of the polyethylene could be directly evidenced by infrared spectroscopy. KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Confocal laser scanning microscopy (LSM) KW - Biodiesel KW - Diesel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608591 DO - https://doi.org/10.1016/j.polymertesting.2024.108547 SN - 0142-9418 VL - 138 SP - 1 EP - 16 PB - Elsevier Ltd. AN - OPUS4-60859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zorn, R. A1 - Szymoniak, Paulina A1 - Kolmangadi, Mohamed Aejaz A1 - Malpass-Evans, R. A1 - McKeown, N. A1 - Jalarvo, N. A1 - Tyagi, M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Microscopic molecular mobility of high-performance polymers of intrinsic microporosity revealed by neutron scattering – bend fluctuations and signature of methyl group rotation N2 - Polymers of intrinsic microporosity exhibit a combination of high gas permeability and reasonable permselectivity, which makes them attractive candidates for gas separation membrane materials. The diffusional selective gas transport properties are connected to the molecular mobility of these polymers in the condensed state. Incoherent quasielastic neutron scattering was carried out on two polymers of intrinsic microporosity, PIM-EA-TB(CH3) and its demethylated counterpart PIM-EA-TB(H2), which have high Brunauer–Emmett–Teller surface area values of 1030 m2 g-1 and 836 m2 g-1, respectively. As these two polymers only differ in the presence of two methyl groups at the ethanoanthracene unit, the effect of methyl group rotation can be investigated solely. To cover a broad dynamic range, neutron time-of-flight was combined with neutron backscattering. The demethylated PIM-EA-TB(H2) exhibits a relaxation process with a weak intensity at short times. As the backbone is rigid and stiff this process was assigned to bendand-flex fluctuations. This process was also observed for the PIM-EA-TB(CH3). A further relaxation process is found for PIM-EA-TB(CH3), which is the methyl group rotation. It was analyzed by a jump-diffusion in a three-fold potential considering also the fact that only a fraction of the present hydrogens in PIM-EATB(CH3) participate in the methyl group rotation. This analysis can quantitatively describe the q dependence of the elastic incoherent structure factor. Furthermore, a relaxation time for the methyl group rotation can be extracted. A high activation energy of 35 kJ mol-1 was deduced. This high activation energy evidences a strong hindrance of the methyl group rotation in the bridged PIM-EA-TB(CH3) structure. KW - Polymers of Intrinsic Microporosity KW - Neutron Scattering PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604114 DO - https://doi.org/10.1039/d4sm00520a SP - 1 EP - 11 PB - RSC AN - OPUS4-60411 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kalbe, Ute A1 - Piechotta, Christian A1 - Bandow, Nicole T1 - Comparing PFAS analysis in batch leaching and column leaching tests N2 - Laboratory leaching tests are tools to assess the mobility of environmental contaminants released from granular materials. Comparative leaching tests were performed using four PFAS-contaminated soils whose concentration patterns of 10 selected perfluoroalkyl and polyfluoroalkyl substances (PFAS) differed due to the two types of contamination sources. This study aimed to evaluate the equivalence of two usual laboratory-scale leaching test procedures, batch and column percolation tests, at liquid-to-solid ratios (L/S) of 2 l/kg, which is the current practice within the German assessment framework, and 10 l/kg (relevant for some EU regulations such as the landfill directive). The differences between the replicates of leaching tests investigating PFAS were smaller for column percolation tests than for batch tests, probably mainly due to the greater sample size and the better representativeness of the sample portion analyzed. It was observed that batch tests overestimate the release of shorter-chain PFAS, whereby the effect was greater with carboxylic than with sulfonic acids. Currently, the limits of detection of analyses given by the DIN standard with regard to PFCA and PFSA in soils are partly not sufficient to detect very low contents, whereas the detection of selected PFCA and PFSA in eluates is more sensitive, in accordance with the available standards. This results in limitations when calculating mass balances. KW - PFAS KW - Leaching KW - Column percolation test KW - Batch test KW - Soil PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618187 DO - https://doi.org/10.1007/s11356-024-35510-0 SN - 1614-7499 VL - 31 IS - 57 SP - 65233 EP - 65251 PB - Springer Science and Business Media LLC AN - OPUS4-61818 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosen, Andrew S. A1 - Gallant, Max A1 - George, Janine A1 - Riebesell, Janosh A1 - Sahasrabuddhe, Hrushikesh A1 - Shen, Jimmy-Xuan A1 - Wen, Mingjian A1 - Evans, Matthew L. A1 - Petretto, Guido A1 - Waroquiers, David A1 - Rignanese, Gian-Marco A1 - Persson, Kristin A. A1 - Jain, Anubhav A1 - Ganose, Alex M. T1 - Jobflow: Computational Workflows Made Simple N2 - We present Jobflow, a domain-agnostic Python package for writing computational workflows tailored for high-throughput computing applications. With its simple decorator-based approach, functions and class methods can be transformed into compute jobs that can be stitched together into complex workflows. Jobflow fully supports dynamic workflows where the full acyclic graph of compute jobs is not known until runtime, such as compute jobs that launch other jobs based on the results of previous steps in the workflow. The results of all Jobflow compute jobs can be easily stored in a variety of filesystem- and cloud-based databases without the data storage process being part of the underlying workflow logic itself. Jobflow has been intentionally designed to be fully independent of the choice of workflow manager used to dispatch the calculations on remote computing resources. At the time of writing, Jobflow workflows can be executed either locally or across distributed compute environments via an adapter to the FireWorks package, and Jobflow fully supports the integration of additional workflow execution adapters in the future. KW - Automation KW - Workflow KW - Computational Materials Science KW - Computations KW - Software PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593104 DO - https://doi.org/10.21105/joss.05995 VL - 9 IS - 93 SP - 1 EP - 7 PB - The Open Journal AN - OPUS4-59310 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghosh, Sheuly A1 - Ueltzen, Katharina A1 - George, Janine A1 - Neugebauer, Jörg A1 - Körmann, Fritz T1 - Chemical ordering and magnetism in face-centered cubic CrCoNi alloy N2 - AbstractThe impact of magnetism on chemical ordering in face-centered cubic CrCoNi medium entropy alloy is studied by a combination of ab initio simulations, machine learning potentials, and Monte Carlo simulations. Large magnetic energies are revealed for some mixed L12/L10 type ordered configurations, which are rooted in strong nearest-neighbor magnetic exchange interactions and chemical bonding among the constituent elements. There is a delicate interplay between magnetism and stability of MoPt2 and L12/L10 type of order, which may explain opposing experimental and theoretical findings. KW - Chemically complex materials KW - Alloys KW - Magnetism KW - Bonding analysis KW - Machine learning KW - Machine-learned interatomic potentials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623114 DO - https://doi.org/10.1038/s41524-024-01439-8 SN - 2057-3960 VL - 10 IS - 1 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-62311 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nicolicea, Alberto A1 - Oliveros-Mata, E. S. A1 - Zabila, Y. A1 - Makarov, D. A1 - Melzer, Michael A1 - Pelkner, Matthias T1 - Flexible anisotropic magnetoresistive sensors for novel magnetic flux leakage testing capabilities N2 - Rigid magnetic field sensors such as anisot Hall sensors have been used for years and have become industry standard for electromagnetic non-destructive testing (NDT). Recent technological developments in the field of flexible electronics allow for the fabrication of reshapeable magnetic field sensors on flexible substrates via thin-film deposition or printing. The magnetic properties of these sensors have comparable characteristics to industry-standard rigid magnetic field sensors, with the added ability of adapting to the surface of complex components and scanning in contact with the sample surface. This improves defect detectability and magnetic signal strength by minimizing the scanning lift-off (LO) distance. In this article flexible AMR sensors mounted on a rotative mechanical holder were used to scan a semi-circular ferromagnetic sample with 3 reference defects via magnetic flux leakage (MFL) testing, thus demonstrating the applicability of this type of sensors for the scanning of curved samples. In order to benchmark the performance of these sensors in comparison to industry standard rigid magnetic field sensors, a ferromagnetic sample with 10 reference defects of different depths was scanned employing flexible AMR and rigid GMR sensors. Defects with depths ranging from 110 μm up to 2240 μm were detected with an signal-tonoise ratio (SNR) of 2.7 up to 27.9 (for flexible AMR sensors) and 6.2 up to 72.3 (for rigid GMR sensors), respectively. A 2D magnetometer mapping of the sample with a spatial scanning step of 10 × 50 μm2 (flexible AMR) and 16 × 100 μm2 (rigid GMR) was obtained. The results show that this type of sensor can be used for high-resolution and high-detail mapping of defects on the surface of planar and non-planar ferromagnetic samples since the scanning lift-off distance is equal to the substrate thickness of 20 μm for in-contact scanning. The SNR comparison between flexible and rigid sensors shows that the performance of the flexible AMR sensors employed is not very far behind the performance of the rigid GMR sensors used. KW - Flexible magnetic field sensors KW - Non-destructive testing KW - Magnetic flux leakage KW - Thin film sensor fabrication KW - Defect detection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-603931 DO - https://doi.org/10.1016/j.ndteint.2024.103160 SN - 0963-8695 VL - 146 SP - 1 EP - 15 PB - Elsevier CY - Amsterdam AN - OPUS4-60393 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidinger, J. A1 - Barkov, V. A1 - Tavakoli, H. A1 - Correa, J. A1 - Ostermann, Markus A1 - Atzmueller, M. A1 - Gebbers, R. A1 - Vogel, S. T1 - Which and how many soil sensors are ideal to predict key soil properties: A case study with seven sensors N2 - Soil sensing enables rapid and cost-effective soil analysis. However, a single sensor often does not generate enough information to reliably predict a wide range of soil properties. Within a case-study, our objective was to identify how many and which combinations of soil sensors prove to be suitable for high-resolution soil mapping. On a subplot of an agricultural field showing a high spatial soil variability, six in-situ proximal soil sensors (PSSs) next to remote sensing (RS) data from Sentinel-2 were evaluated based on their capabilities to predict a set of soil properties including: soil organic carbon, pH, moisture as well as plant-available phosphorus, magnesium and potassium. The set of PSSs consisted of ion-selective pH electrodes, a capacitive soil moisture sensor, an apparent soil electrical conductivity measuring system as well as passive gamma-ray-, X-ray fluorescence- and nearinfrared spectroscopy. All possible combinations of sensors were exhaustively evaluated and ranked based on their predict KW - XRF KW - Soil KW - Remote Sensing KW - Precision agriculture PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613920 DO - https://doi.org/10.1016/j.geoderma.2024.117017 VL - 450 SP - 1 EP - 17 PB - Elsevier B.V. AN - OPUS4-61392 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Paul, Andrea A1 - Liestmann, Zoe A1 - Zaenker, Steffen A1 - Vogel, Kristin A1 - Broszies, Tanja A1 - Ostermann, Markus T1 - How reliable is the X‐ray fluorescence‐based differentiation between glass wool and rock wool and the age classification of rock wool? N2 - AbstractA prerequisite for the recycling of mineral wool is information about the type of material, that is, whether it is glass wool or rock wool. As mineral wool produced before the year 2000 can be potentially carcinogenic, it is furthermore important to distinguish between “old” and “new” wool when handling the material. Based on VDI 3492, it is possible to determine the material and, in the case of rock wool, the age by analyzing the mass fractions of eight oxides, which are the main components of mineral wool. This study presents the X‐ray fluorescence (XRF) analyses of 141 man‐made mineral fibers collected in Germany. Only in a few cases it was not possible to clearly assign the material type. In contrast, the identification of “old” and “new” rock wool posed a challenge as there were many borderline samples. Based on the available data, a chemometric model was developed that can classify “old” and “new” RW with a sensitivity of 93% and 89% and with a specificity of 100% in both cases. However, care must be taken when oxide contents are close to the specification limits. The reason for this mainly lies in the overlapping intervals of key oxides as suggested by VDI 3492, and, to a lesser extent, in the uncertainties typically occurring in the XRF‐based analysis of oxides. With this study, a comprehensive collection and evaluation of XRF data on mineral wool is made available, which can serve as a reference database for future users. KW - Mineral wool KW - RFA KW - Multivariate data analysis KW - VDI 3492 PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610285 DO - https://doi.org/10.1002/xrs.3451 SN - 1097-4539 SP - 1 EP - 11 PB - Wiley CY - New York, NY AN - OPUS4-61028 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Thiele, Isabel A1 - Santolin, Lara A1 - Meyer, Klas A1 - Machatschek, Rainhard A1 - Bölz, Uwe A1 - Tarazona, Natalia A. A1 - Riedel, Sebastian L. T1 - Microbially synthesized poly(hydroxybutyrate-co-hydroxyhexanoate) with low to moderate hydroxyhexanoate content: Properties and applications N2 - Plastic pollution is the biggest environmental concern of our time. Breakdown products like micro- and nanoplastics inevitably enter the food chain and pose unprecedented health risks. In this scenario, bio-based and biodegradable plastic alternatives have been given a momentum aiming to bridge a transition towards a more sustainable future. Polyhydroxyalkanoates (PHAs) are one of the few thermoplastic polymers synthesized 100 % via biotechnological routes which fully biodegrade in common natural environments. Poly(hydroxybutyrate-cohydroxyhexanoate) [P(HB-co-HHx)] is a PHA copolymer with great potential for the commodity polymers industry, as its mechanical properties can be tailored through fine-tuning of its molar HHx content. We have recently developed a strategy that enables for reliable tailoring of the monomer content of P(HB-co-HHx). Nevertheless, there is often a lack of comprehensive investigation of the material properties of PHAs to evaluate whether they actually mimic the functionalities of conventional plastics. We present a detailed study of P(HB-co-HHx) copolymers with low to moderate hydroxyhexanoate content to understand how the HHx monomer content influences the thermal and mechanical properties and to link those to their abiotic degradation. By increasing the HHx fractions in the range of 2 – 14 mol%, we impart an extension of the processing window and application range as the melting temperature (Tm) and glass temperature (Tg) of the copolymers decrease from Tm 165 ◦C to 126 ◦C, Tg 4 ◦C to − 5.9 ◦C, accompanied by reduced crystallinity from 54 % to 20 %. Elongation at break was increased from 5.7 % up to 703 % at 14 mol% HHx content, confirming that the range examined was sufficiently large to obtain ductile and brittle copolymers, while tensile strength was maintained throughout the studied range. Finally, accelerated abiotic degradation was shown to be slowed down with an increasing HHx fraction decreasing from 70 % to 55 % in 12 h. KW - Molecular Biology KW - General Medicine KW - Biochemistry KW - Structural Biology PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595636 DO - https://doi.org/10.1016/j.ijbiomac.2024.130188 VL - 263 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-59563 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Villajos Collado, José Antonio A1 - Balderas‐Xicohténcatl, Rafael A1 - Al Shakhs, Ali N. A1 - Berenguer‐Murcia, Ángel A1 - Buckley, Craig E. A1 - Cazorla‐Amorós, Diego A1 - Charalambopoulou, Georgia A1 - Couturas, Fabrice A1 - Cuevas, Fermin A1 - Fairen‐Jimenez, David A1 - Heinselman, Karen N. A1 - Humphries, Terry D. A1 - Kaskel, Stefan A1 - Kim, Hyunlim A1 - Marco‐Lozar, Juan P. A1 - Oh, Hyunchul A1 - Parilla, Philip A. A1 - Paskevicius, Mark A1 - Senkovska, Irena A1 - Shulda, Sarah A1 - Silvestre‐Albero, Joaquin A1 - Steriotis, Theodore A1 - Tampaxis, Christos A1 - Hirscher, Michael A1 - Maiwald, Michael T1 - Establishing ZIF‐8 as a reference material for hydrogen cryoadsorption: An interlaboratory study N2 - AbstractHydrogen storage by cryoadsorption on porous materials has the advantages of low material cost, safety, fast kinetics, and high cyclic stability. The further development of this technology requires reliable data on the H2 uptake of the adsorbents, however, even for activated carbons the values between different laboratories show sometimes large discrepancies. So far no reference material for hydrogen cryoadsorption is available. The metal‐organic framework ZIF‐8 is an ideal material possessing high thermal, chemical, and mechanical stability that reduces degradation during handling and activation. Here, we distributed ZIF‐8 pellets synthesized by extrusion to 9 laboratories equipped with 15 different experimental setups including gravimetric and volumetric analyzers. The gravimetric H2 uptake of the pellets was measured at 77 K and up to 100 bar showing a high reproducibility between the different laboratories, with a small relative standard deviation of 3–4 % between pressures of 10–100 bar. The effect of operating variables like the amount of sample or analysis temperature was evaluated, remarking the calibration of devices and other correction procedures as the most significant deviation sources. Overall, the reproducible hydrogen cryoadsorption measurements indicate the robustness of the ZIF‐8 pellets, which we want to propose as a reference material. KW - Physical and theoretical chemistry KW - Atomic and molecular physics, and optics PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594788 DO - https://doi.org/10.1002/cphc.202300794 SN - 1439-7641 SP - 1 EP - 7 PB - Wiley CY - Weinheim AN - OPUS4-59478 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhuang, Y. A1 - Spahr, S. A1 - Lutze, H.V. A1 - Reith, C.J. A1 - Hagemann, N. A1 - Paul, Andrea A1 - Haderlein, S.B. T1 - Persulfate activation by biochar and iron: Effect of chloride on formation of reactive species and transformation of N,N-diethyl-m-toluamide (DEET) N2 - Fenton-like processes using persulfate for oxidative water treatment and contaminant removal can be enhanced by the addition of redox-active biochar, which accelerates the reduction of Fe(III) to Fe(II) and increases the yield of reactive species that react with organic contaminants. However, available data on the formation of non-radical or radical species in the biochar/Fe(III)/persulfate system are inconsistent, which limits the evaluation of treatment efficiency and applicability in different water matrices. Based on competition kinetics calculations, we employed different scavengers and probe compounds to systematically evaluate the effect of chloride in presence of organic matter on the formation of major reactive species in the biochar/Fe(III)/persulfate system for the transformation of the model compound N,N‑diethyl-m-toluamide (DEET) at pH 2.5. We show that the transformation of methyl phenyl sulfoxide (PMSO) to methyl phenyl sulfone (PMSO2) cannot serve as a reliable indicator for Fe(IV), as previously suggested, because sulfate radicals also induce PMSO2 formation. Although the formation of Fe(IV) cannot be completely excluded, sulfate radicals were identified as the major reactive species in the biochar/Fe(III)/persulfate system in pure water. In the presence of dissolved organic matter, low chloride concentrations (0.1 mM) shifted the major reactive species likely to hydroxyl radicals. Higher chloride concentrations (1 mM), as present in a mining-impacted acidic surface water, resulted in the formation of another reactive species, possibly Cl2•−, and efficient DEET degradation. To tailor the application of this oxidation process, the water matrix must be considered as a decisive factor for reactive species formation and contaminant removal. KW - Water treatment KW - Organic contaminants KW - Fenton-like systems KW - Radicals KW - ESR PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608677 DO - https://doi.org/10.1016/j.watres.2024.122267 SN - 0043-1354 VL - 265 SP - 1 EP - 8 PB - Elsevier Ltd. AN - OPUS4-60867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - You, Zengchao A1 - Winckelmann, Alexander A1 - Vogl, Jochen A1 - Recknagel, Sebastian A1 - Abad Andrade, Carlos Enrique T1 - Determination of calcium, iron, and selenium in human serum by isotope dilution analysis using nitrogen microwave inductively coupled atmospheric pressure plasma mass spectrometry (MICAP-MS) N2 - In this study, we demonstrate the applicability of nitrogen microwave inductively coupled atmospheric pressure mass spectrometry (MICAP-MS) for Ca, Fe, and Se quantification in human serum using isotope dilution (ID) analysis. The matrix tolerance of MICAP-MS in Na matrix was investigated, uncovering that high Na levels can suppress the signal intensity. This suppression is likely due to the plasma loading and the space charge effect. Moreover, 40Ca and 44Ca isotopic fractionation was noted at elevated Na concentration. Nine certified serum samples were analyzed using both external calibration and ID analysis. Overestimation of Cr, Zn, As, and Se was found in the results of external calibration, which might be resulted from C-induced polyatomic interference and signal enhancement, respectively. Further investigations performed with methanol showed a similar enhancement effect for Zn, As, and Se, potentially supporting this assumption. The mass concentrations determined with ID analysis show metrological compatibility with the reference values, indicating that MICAP-MS combined with ID analysis can be a promising method for precise Ca, Fe, and Se determination. Moreover, this combination reduces the influences of matrix effects, broadening the applicability of MICAP-MS for samples with complex matrix. KW - Selenium KW - Nitrogen microwave inductively coupled atmospheric pressure mass spectrometry KW - Isotope dilution KW - Human serum KW - Calcium KW - Iron PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598664 DO - https://doi.org/10.1007/s00216-024-05274-0 SN - 1618-2642 SP - 3117 EP - 3125 PB - Springer CY - Berlin AN - OPUS4-59866 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Assessment of keyhole stability in laser beam welding with external magnetic field using numerical simulation N2 - The challenge of understanding the physical mechanisms behind porosity reduction by a magnetic field during laser beam welding (LBW) is partly due to the difficulty in quantitatively evaluating keyhole stability. The commonly used index, such as keyhole depth, is typically one-dimensional, which is insufficient to capture the dynamic and three-dimensional fluctuations of the keyhole. In this paper, by utilizing a 3D multiphysical model of LBW with magnetic field, a novel keyhole geometry reconstruction algorithm has been developed to describe the keyhole profile and its fluctuation in a statistical manner to evaluate keyhole stability quantitatively. An equivalent diameter is proposed in this algorithm to reduce the irregularity of the keyhole geometry. The calculation results indicate that the time-averaged keyhole shape over 300 ms in the LBW of steel is conical, regardless of the application of an external magnetic field, which provides a more representative shape. Meanwhile, it is observed from the statistical aspect that the keyhole diameter becomes smaller, except the top part, under the influence of the magnetic field. The standard deviation of the equivalent diameter can be used as a physical variable to assess the keyhole stability quantitatively. The application of an external magnetic field can produce a noticeable reduction of the standard deviation of the equivalent diameter, namely, stabilizing the keyhole during LBW of steel. However, the different contribution from the keyhole stability affected by a magnetic field in suppressing porosity is different with materials. T2 - International Congress of Applications of Lasers & Electro-Optics 2024 CY - Hollywood, Los Angeles, USA DA - 04.11.2024 KW - Deep penetration laser beam welding KW - Numerical simulation KW - Keyhole shape KW - Keyhole stability KW - Magnetic field PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616024 DO - https://doi.org/10.2351/7.0001528 VL - 36 IS - 4 SP - 1 EP - 7 PB - AIP Publishing AN - OPUS4-61602 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Völker, Tobias A1 - Gornushkin, Igor B. T1 - Mass and mole fractions in calibration-free LIBS N2 - This technical note highlights the fact that CF-LIBS algorithms work in mole fractions, while results of spectrochemical analysis are usually reported in mass fractions or mass percent. Ignoring this difference and not converting mole fractions to mass fractions can lead to errors in reported concentrations determined by the CF-LIBS method and inadequate comparison of these concentrations with certified concentrations. Here, the key points of the CF-LIBS algorithm are reproduced and the formulae for converting a mole fraction to a mass fraction and vice versa are given. Several numerical examples are also given, which show that the greater the difference between the molar mass of an individual element in a sample and the average molar mass, the greater the discrepancy between the mole and mass fractions. KW - Spectroscopy KW - Analytical Chemistry KW - LIBS KW - Calibration PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-598611 DO - https://doi.org/10.1039/d4ja00028e SN - 0267-9477 VL - 39 IS - 4 SP - 1030 EP - 1032 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59861 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabhakara, Prathik A1 - Lay, Vera A1 - Mielentz, Frank A1 - Niederleithinger, Ernst A1 - Behrens, Matthias T1 - Enhancing the Performance of a Large Aperture Ultrasound System (LAUS): A Combined Approach of Simulation and Measurement for Transmitter–Receiver Optimization N2 - The Large Aperture Ultrasound System (LAUS) developed at BAM is known for its ability to penetrate thick objects, especially concrete structures commonly used in nuclear waste storage and other applications in civil engineering. Although the current system effectively penetrates up to ~9 m, further optimization is imperative to enhance the safety and integrity of disposal structures for radioactive or toxic waste. This study focuses on enhancing the system’s efficiency by optimizing the transducer spacing, ensuring that resolution is not compromised. An array of twelve horizontal shear wave transducers was used to find a balance between penetration depth and resolution. Systematic adjustments of the spacing between transmitter and receiver units were undertaken based on target depth ranges of known reflectors at depth ranges from 5 m to 10 m. The trade-offs between resolution and artifact generation were meticulously assessed. This comprehensive study employs a dual approach using both simulations and measurements to investigate the performance of transducer units spaced at 10 cm, 20 cm, 30 cm, and 40 cm. We found that for depths up to 5 m, a spacing of 10 cm for LAUS transducer units provided the best resolution as confirmed by both simulations and measurements. This optimal distance is particularly effective in achieving clear reflections and a satisfactory signal-to-noise ratio (SNR) in imaging scenarios with materials such as thick concrete structures. However, when targeting depths greater than 10 m, we recommend increasing the distance between the transducers to 20 cm. This increased spacing improves the SNR in comparison to other spacings, as seen in the simulation of a 10 m deep backwall. Our results emphasize the critical role of transducer spacing in achieving the desired SNR and resolution, especially in the context of depth imaging requirements for LAUS applications. In addition to the transducer spacing, different distances between individual sets of measurement positions were tested. Overall, keeping the minimal possible distance between measurement position offsets provides the best imaging results at greater depths. The proposed optimizations for the LAUS in this study are primarily relevant to applications on massive nuclear structures for nuclear waste management. This research highlights the need for better LAUS efficiency in applications such as sealing structures, laying the foundation for future technological advances in this field. KW - Engineered barrier system KW - Phased array technique KW - Ultrasonic testing KW - Non-destructive testing in civil engineering KW - Seismic migration PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-592426 DO - https://doi.org/10.3390/s24010100 VL - 24 IS - 1 SP - 1 EP - 23 PB - MDPI CY - Basel, Switzerland AN - OPUS4-59242 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Maack, Stefan A1 - Buske, Stefan T1 - Application of iterative elastic SH reverse time migration to synthetic ultrasonic echo data N2 - The ultrasonic echo technique is widely used in non-destructive testing (NDT) of concrete objects for thickness measurements, geometry determinations and localization of built-in components. To improve ultrasonic imaging of complex concrete structures, we transferred a seismic imaging technique, the Reverse Time Migration (RTM), to NDT in civil engineering. RTM, in contrast to the conventionally used synthetic aperture focusing technique (SAFT) algorithms, considers all wavefield types and thus, can handle complex wave propagations in any direction with no limit on velocity variations and reflector dip. In this paper, we focused on the development, application and evaluation of a two-dimensional elastic RTM algorithm considering horizontally polarized shear (SH) waves only. We applied the elastic SH RTM routine to synthetic ultrasonic echo SH-wave data generated with a concrete model incorporating several steps and circular cavities. As these features can often be found in real-world NDT use cases, their imaging is extremely important. By using elastic SH RTM, we were able to clearly reproduce almost all reflectors inside the concrete model including the vertical step edges and the cross sections of the cavities.We were also capable to show that more features could be mapped compared to SAFT, and that imaging of complex reflectors could be sharpened compared to elastic P-SV (compressional-vertically polarized shear) RTM. Our promising results illustrate that elastic SH RTM has the potential to significantly enhance the reconstruction of challenging concrete structures, representing an important step forward for precise, high-quality ultrasonic NDT in civil engineering. KW - Ultrasonic echo technique KW - Concrete structures KW - Elastic reverse time migration KW - Synthetic aperture focusing technique KW - Horizontally polarized shear waves PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-591716 DO - https://doi.org/10.1007/s10921-023-01010-3 SN - 1573-4862 VL - 43 SP - 1 EP - 16 PB - Springer Science and Business Media CY - Dordrecht AN - OPUS4-59171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Prabitz, Konstantin Manuel A1 - Antretter, Thomas A1 - Rethmeier, Michael A1 - El-Sari, Bassel A1 - Schubert, Holger A1 - Hilpert, Benjamin A1 - Gruber, Martin A1 - Sierlinger, Robert A1 - Ecker, Werner T1 - Numerical and experimental assessment of liquid metal embrittlement in externally loaded spot welds N2 - Zinc-based surface coatings are widely applied with high-strength steels in automotive industry. Some of these base materials show an increased brittle cracking risk during loading. It is necessary to examine electrogalvanized and uncoated samples of a high strength steel susceptible to liquid metal embrittlement during spot welding with applied external load. Therefore, a newly developed tensile test method with a simultaneously applied spot weld is conducted. A fully coupled 3D electrical, thermal, metallurgical and mechanical finite element model depicting the resistant spot welding process combined with the tensile test conducted is mandatory to correct geometric influences of the sample geometry and provides insights into the sample’s time dependent local loading. With increasing external loads, the morphology of the brittle cracks formed is affected more than the crack depth. The validated finite element model applies newly developed damage indicators to predict and explain the liquid metal embrittlement cracking onset and development as well as even ductile failure. KW - Resistance spot welding KW - Finite element simulation KW - Advanced high-strength steel KW - Liquid metal embrittlement KW - Damage prediction KW - Tensile resistance spot welding experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594848 DO - https://doi.org/10.1007/s40194-024-01696-7 SN - 0043-2288 SP - 1 EP - 10 PB - Springer Science and Business Media LLC AN - OPUS4-59484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Strobl, Dominic A1 - Unger, Jörg F. A1 - Ghnatios, C. A1 - Klawoon, Alexander A1 - Pittner, Andreas A1 - Rethmeier, Michael A1 - Robens-Radermacher, Annika T1 - Efficient bead-on-plate weld model for parameter estimation towards effective wire arc additive manufacturing simulation N2 - Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a beadon-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature. The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data. KW - Proper generalized decomposition KW - Model order reduction KW - Hardly separable problem KW - Additive manufacturing KW - Model calibration KW - Wire arc additive manufacturing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596502 DO - https://doi.org/10.1007/s40194-024-01700-0 SN - 0043-2288 SP - 1 EP - 18 PB - Springer AN - OPUS4-59650 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Timofeev, Juri A1 - Azari, H. A1 - Satyanarayana, R. T1 - Controlled Creating of Delaminations in Concrete for Nondestructive Testing N2 - Locating and sizing delaminations is a common inspection task in the maintenance and quality control of construction and rehabilitation. Their detection is an important area of application of nondestructive testing in civil engineering (NDT-CE). To improve this application, NDT test systems and test solutions must be compared, for which specimens containing well-defined delaminations are needed to serve as a reference. Currently, there are no widely accepted procedures available for creating such flaws locally and reproducibly. This study presents procedures for creating artificial delaminations repeatably and as close as possible to natural delaminations. To produce the discontinuities only substances were used which can occur in concrete components and do not affect the application of NDT-CE methods. Ultrasonic pulse-echo (UPE) was used to test the flaws in the specimens. The delaminations were created by applying expansive mortar in prepared through holes. Three specimens with two delaminations each were built and tested using UPE. KW - Concrete KW - Reference KW - Delamination KW - Test specimen KW - Non-destructive testing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595201 DO - https://doi.org/10.1007/s10921-023-01044-7 SN - 0195-9298 VL - 43 IS - 1 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hartwig, Philipp A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Scheunemann, Lisa A1 - Schröder, Jörg A1 - Rethmeier, Michael T1 - A Physically Motivated Heat Source Model for Laser Beam Welding N2 - In this contribution, we present a physically motivated heat source model for the numerical modeling of laser beam welding processes. Since the calibration of existing heat source models, such as the conic or Goldak model, is difficult, the representation of the heat source using so-called Lamé curves has been established, relying on prior Computational Fluid Dynamics (CFD) simulations. Lamé curves, which describe the melting isotherm, are used in a subsequent finite-element (FE) simulation to define a moving Dirichlet boundary condition, which prescribes a constant temperature in the melt pool. As an alternative to this approach, we developed a physically motivated heat source model, which prescribes the heat input as a body load directly. The new model also relies on prior CFD simulations to identify the melting isotherm. We demonstrate numerical results of the new heat source model on boundary-value problems from the field of laser beam welding and compare it with the prior CFD simulation and the results of the Lamé curve model and experimental data. KW - Welding simulation KW - Heat source models KW - Laser beam welding KW - Thermal analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600899 DO - https://doi.org/10.3390/met14040430 VL - 14 IS - 4 SP - 1 EP - 26 PB - MDPI CY - Basel AN - OPUS4-60089 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, Maria A1 - Niederleithinger, Ernst A1 - Büttner, Christoph A1 - Buske, Stefan T1 - Application of iterative elastic reverse time migration to shear horizontal ultrasonic echo data obtained at a concrete step specimen N2 - The ultrasonic echo technique is broadly applied in non‐destructive testing (NDT) of concrete structures involving tasks such as measuring thickness, determining geometry and locating built‐in elements. To address the challenge of enhancing ultrasonic imaging for complex concrete constructions, we adapted a seismic imaging algorithm – reverse time migration (RTM) – for NDT in civil engineering. Unlike the traditionally applied synthetic aperture focusing technique (SAFT), RTM takes into account the full wavefield including primary and reflected arrivals as well as multiples. This capability enables RTM to effectively handle all wave phenomena, unlimited by changes in velocity and reflector inclinations. This paper concentrates on applying and evaluating a two‐dimensional elastic RTM algorithm that specifically addresses horizontally polarized shear (SH) waves only, as these are predominantly used in ultrasonic NDT of concrete structures. The elastic SH RTM algorithm was deployed for imaging real ultrasonic echo SH‐wave data obtained at a concrete specimen exhibiting a complex back wall geometry and containing four tendon ducts. As these features are frequently encountered in practical NDT scenarios, their precise imaging holds significant importance. By applying the elastic SH RTM algorithm, we successfully reproduced nearly all reflectors within the concrete specimen. In particular, we were capable of accurately reconstructing all vertically oriented reflectors as well as the circular cross sections of three tendon ducts, which was not achievable with traditional SAFT imaging. These findings demonstrate that elastic SH RTM holds the ability to considerably improve the imaging of complex concrete geometries, marking a crucial advancement for accurate, high‐quality ultrasonic NDT in civil engineering. KW - Engineering KW - Finite-Difference Time Domain KW - Non-Destructive KW - Seismic KW - Migration KW - Ultrasonic-Echo Technique PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608744 DO - https://doi.org/10.1002/nsg.12318 SN - 1569-4445 VL - 2024 SP - 1 EP - 22 PB - Wiley AN - OPUS4-60874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bahrami Eskandari, Ardalan A1 - Nikkhoo, Ali A1 - Hajirasouliha, Iman T1 - Analyzing Vertical Earthquake Vibrations and Moving Vehicle Loads for Structural Health Monitoring and Vibration Suppression in Bridges N2 - The design of bridges often overlooks the vertical component of earthquakes or considers it of secondary importance, despite compelling evidence indicating specific structural damage caused by primary earthquake waves. Conversely, during the operational phase, the combined influence of ground motion and moving loads from vehicles can significantly impact the structural health monitoring (SHM) of bridges. This study aims to evaluate the simultaneous effect of vertical earthquake vibrations and moving vehicle loads on simply supported bridges. The research employs a practical methodology based on the eigenfunction expansion method to analyze change of deflection due to the effect of these concurrent forces under seven different earthquake records. It is shown that within a realistic range of vehicle mass and velocity, the average of changing the maximum deflection at the mid-span of the main beam (denoted as M_n) reaches up to 163% under various scenarios. Subsequently, the seismic parameters influencing this phenomenon are identified through a statistical analysis of set of 100 different earthquake records with unique features. A linear regression equation is presented to predict the M_n based on the earthquake specific properties. Additionally, to control the vertical vibration of bridge systems, a novel vibration suppression system utilizing steel pipe dampers is introduced, and its reliability is examined across a broad spectrum of bridge flexural rigidity. The results indicate that the system's efficiency depends on M_n and the soil type of the bridge construction, enabling a reduction in structural sections (up to 27%) while achieving the same maximum target deflection in the initial state. This efficiency leads to a more economical design solution, emphasizing the potential benefits of the proposed system for practical application. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 10.06.2024 KW - Bridge structures KW - Vertical earthquakes KW - Health monitoring KW - Moving vehicles KW - Suppressing vibrations PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604893 DO - https://doi.org/10.58286/29746 SP - 1 EP - 10 PB - NDT.net AN - OPUS4-60489 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bahrami Eskandari, Ardalan A1 - Küttenbaum, Stefan T1 - NDT Data-Supported Structural Reassessments based on Regression Relations in Measuring Data Analysis N2 - Non-destructive Testing (NDT) provides valuable data about structural elements, supporting the assessment of existing infrastructures without incurring additional structural damage from inspections. Simultaneously, the uncertainty in measurement, which quantifies the quality of measurement results, plays a crucial role in decisions aimed at, e.g., optimizing maintenance strategies, rehabilitation works and Structural Health Monitoring (SHM) implementations. The Guide to the Expression of Uncertainty in Measurement (GUM) framework has already been considered for non-destructive concrete testing. Regarding that, extensive measurements with sophisticated scopes need to be conducted by experts as an obligatory process. This study illustrates how NDT results describing the inner structure of a concrete element can effectively support the reassessment of bridges in operation. To achieve this, the study considers the various measurable positions of the resisting longitudinal tendons of a bridge structure to investigate the displacement change under dynamic service loads. Furthermore, this study aims to simplify and optimize existing NDT data analysis procedures by employing regression analysis, enabling the detection of structural features. This regression analysis yields a modifier for determining the correct depth of an object within the structural element. The method is validated through laboratory experiments, including the use of an ultrasonic measurement system. As a result, it provides unbiased and accurately measured results, while ensuring that the measurement data can remain uncorrelated. Major advantages include efficient computation, a wider scope, and avoiding redundant information about the measuring process. The findings demonstrate that employing the proposed NDT analysis method, with its enhanced practicability, can significantly augment the efficiency of NDT data-supported structural reassessments across various scenarios. T2 - EWSHM 2024 CY - Potsdam, Germany DA - 10.06.2024 KW - Existing structures KW - Non-destructive testing KW - Practicality measurement KW - Bridge reassessment KW - Statistical analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604825 DO - https://doi.org/10.58286/29714 SN - 1435-4934 SP - 1 EP - 9 PB - NDT.net AN - OPUS4-60482 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bertola, N. A1 - Schumacher, T. A1 - Niederleithinger, Ernst A1 - Bruehwiler, E. T1 - Early detection of structural damage in UHPFRC structures through the combination of acoustic emission and ultrasonic stress wave monitoring N2 - Ultra-High-Performance Fiber-Reinforced Cementitious Composite (UHPFRC) offers several advantages compared to concrete, notably due to the strain hardening behavior under tensile actions. Structures made of this composite material are lightweight and highly durable, thanks to the UHPFRC waterproofing quality. Nonetheless, the tensile behavior leads to a different cracking pattern than conventional concrete and is not fully understood yet. This paper presents a combined approach using both passive ultrasonic (US) stress wave (or acoustic emission) and active US stress wave monitoring to localize and quantify damage progression in a full-scale UHPFRC beam during experimental load testing. The proposed monitoring approach involves 24 US transducers that are embedded randomly throughout a 4.2- meter-long laboratory UHPFRC T-beam. Continuous monitoring enabled accurate localization of US stress sources caused by loading-induced cracking as well as from pulses generated by the embedded US transducers. This study shows that it is possible to predict the location and shape of the macro-crack that is linked to structural failure early on, i.e., just after the end of the elastic domain. This combined approach opens new possibilities to monitor the structural behavior and detect damage on UHPFRC structures before they affect the structural behavior in terms of deflection and strain. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 11.6.2024 KW - UHPFRC KW - Acoustic emission KW - Damage detection PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604708 UR - https://www.ndt.net/article/ewshm2024/papers/477_manuscript.pdf DO - https://doi.org/10.58286/29698 SN - 1435-4934 SP - 1 EP - 8 PB - NDT.net AN - OPUS4-60470 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schumacher, T. A1 - Bertola, N. A1 - Epple, Niklas A1 - Bruehwiler, E. A1 - Niederleithinger, Ernst T1 - Combined Passive and Active Ultrasonic Stress Wave Monitoring of Concrete Structures: An Overview of Data Analysis Techniques and Their Applications and Limitations N2 - Combined passive ultrasonic (US) stress wave [better known as acoustic emission (AE)] and active US stress wave monitoring has been shown to provide a more holistic picture of ongoing fracture processes, damage progression, as well as slowly occurring aging and degradation mechanisms in concrete structures. Traditionally, different data analysis techniques have been used to analyze the data generated from these two monitoring techniques. For passive US stress wave monitoring, waveform amplitudes, hit rates, source localization, and b-value analysis, among others, have been used to detect and locate cracking. On the other hand, amplitude tracking, magnitude squared coherence (MSC), and coda wave interferometry (CWI) are examples of analyses that have been employed for active US stress wave monitoring. In this paper, we explore some of these data analysis techniques and show where their respective applications and limitations might be. After providing an overview of the monitoring approach and the different data analysis techniques, results and observations from selected laboratory experiments are discussed. Finally, suggestions for further work are proposed. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 11.06.2024 KW - Ultrasound KW - Acoustic emission KW - Concrete KW - Stress PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604687 UR - https://www.ndt.net/article/ewshm2024/papers/824_manuscript.pdf DO - https://doi.org/10.58286/29863 SN - 1435-4934 SP - 1 EP - 8 PB - NDT.net AN - OPUS4-60468 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Skłodowska, Anna A1 - Baensch, Franziska A1 - Lay, Vera A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - Acoustic emission monitoring for engineered barriers in nuclear waste disposal N2 - To safely dispose of nuclear waste in underground facilities, engineered barrier systems are needed to seal shafts and galleries. The material used in these barriers must be adapted to the host rock parameters. Shrinking and cracking must be avoided to provide a barrier with almost zero permeability. For repositories in salt rock environments, several types of salt concrete (SC) are possible construction materials. Within the project SealWasteSafe, we compared the behavior of an innovative alkali-activated material (AAM) with standard SC in their hydration and hardening phase. To monitor the microstructural changes within the two materials SC and AAM, acoustic emission (AE) signals have been recorded for up to ~250 days on 340-litercubic specimens. The phenomenon of AE is defined as the emission of elastic waves in materials due to the release of localized internal energy. Such energy release can be caused by the nucleation of micro-fracture, e.g., in concrete while curing or when exposed to load. The occurrence of AE events gives first rough indications of microstructural changes and potentially occurring cracking and thus, provides insights for structural health monitoring (SHM). The results show, that for the first 28 days after casting, less AE activity was detected in the AAM compared to SC. After 61 days, in the AAM material, the number of AE events exceeded those observed in the SC. However, the majority of the AE detected and located in AAM was related to surface effects, and not to microstructural changes or occurring cracks within the bulk volume. Additionally, the source location analysis indicated, that despite lower activity in SC, we observed some clustering of the events. In contrast, in AAM, the activity inside the specimen is randomly distributed over the whole volume. The monitoring results help to estimate the material’s sealing properties which are crucial to assess their applicability as sealing material for engineered barriers. T2 - 11th European Workshop on Structural Health Monitoring (EWSHM 2024) CY - Potsdam, Germany DA - 11.06.2024 KW - Endlager KW - Barriere KW - AAM KW - Akustische Emission PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604699 UR - https://www.ndt.net/article/ewshm2024/papers/768_manuscript.pdf DO - https://doi.org/10.58286/29834 SN - 1435-4934 SP - 1 EP - 7 PB - NDT.net AN - OPUS4-60469 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Srinivasan, Krishnanand A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Laser Metal Deposition of Rene 80—Microstructure and Solidification Behavior Modelling N2 - New developments in nickel-based superalloys and production methods, such as the use of additive manufacturing (AM), can result in innovative designs for turbines. It is crucial to understand how the material behaves during the AM process to advance the industrial use of these techniques. An analytical model based on reaction–diffusion formalism is developed to better explain the solidification behavior of the material during laser metal deposition (LMD). The well-known Scheil–Gulliver theory has some drawbacks, such as the assumption of equilibrium at the solid–liquid interface, which is addressed by this method. The solidified fractions under the Scheil model and the pure equilibrium model are calculated using CALPHAD simulations. A differential scanning calorimeter is used to measure the heat flow during the solid–liquid phase transformation, the result of which is further converted to solidified fractions. The analytical model is compared with all the other models for validation. KW - Laser metal deposition KW - Solidification behavior KW - Additive manufacturing KW - Analytical model KW - Nickel‐based superalloy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612095 DO - https://doi.org/10.3390/mi15101234 SN - 2072-666X VL - 15 IS - 10 SP - 1 EP - 14 PB - MDPI AN - OPUS4-61209 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Determination of critical local straining conditions for solidification cracking at laser beam welding by experimental and numerical methods N2 - AbstractThe phenomenon of solidification cracking has been the subject of numerous research projects over the years. Great efforts have been made to understand the fundamentals of hot cracking. It is generally agreed that solidification cracks form in the solidification range between the liquidus and solidus temperatures under the combination of thermal, metallurgical and mechanical factors. There is still a need to determine the time‐resolved strain distribution in the crack‐sensitive region in order to analyse the local critical conditions for solidification cracking phenomena. This was a strong motivation for the development of a measurement system used in this study to estimate the local strains and strain rates in the zone where the solidification crack is expected to occur. The laser beam welding experiments were conducted using the Controlled‐Tensile‐Weldability test (CTW test) to apply an external strain condition during welding to generate solidification cracks. The CTW test is a test method for investigating the susceptibility of laser‐welded joints to solidification cracking, in which the sample can be subjected to a defined strain at a defined strain rate during welding.In combination with experimental investigations, numerical simulations provide spatially detailed and time‐dependent information about the strain development during the welding process, especially regarding the critical conditions for solidification cracking. Therefore, this tool was also used in the present study to evaluate the accuracy of measurement methods and to estimate experimentally derived values and their concrete influence on the formation of solidification cracks. By integrating experimental methods and numerical simulations, this study investigates the spatially resolved and temporally changing development of strain during welding, with a particular focus on the critical conditions that lead to the formation of solidification cracks. The use of numerical simulations serves a dual purpose by validating the accuracy of measurement methods and examining experimentally determined values for their actual influence on the formation of solidification cracks. A three‐dimensional finite element (FE) model implemented with ANSYS is used to simulate strains and stresses during welding. The credibility of the model was first established by validation using experimental temperature measurements. Subsequently, structural simulations were carried out under external load. The results of the simulations showed commendable agreement with the strain measurements performed using the developed technique. KW - Laser beam welding KW - Solidification cracking KW - FEM simulation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612044 DO - https://doi.org/10.1002/pamm.202400020 SN - 1617-7061 VL - 24 IS - 2 SP - 1 EP - 16 PB - Wiley AN - OPUS4-61204 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gumenyuk, Andrey A1 - Üstündağ, Ömer A1 - Pelz, Till A1 - Bakir, Nasim A1 - Gerhards, Benjamin A1 - Schleser, Markus A1 - Rethmeier, Michael T1 - Single pass laser vacuum welding of thick steel plates using electromagnetic support N2 - The increasing demand for renewable energy produced by offshore wind turbines goes along with an increased demand in the production of offshore wind turbine foundations, so called “monopiles”, which are made by joining thick metal sheets. The industrial standard of multi-layer submerged arc welding (SAW) for joining of thick metal sheets is the current bottleneck in the production of monopiles. A possible increase in productivity by the implementation of high-power laser welding in a newly developed mobile vacuum chamber (MoVac) and an electromagnetic root support is the subject of this study. Single run butt welds are performed in flat position on S355 mild steel of thicknesses up to 80 mm using a disc laser system with 1030 nm wavelength and a maximum output of 60 kW. The laser optic is fixed on the MoVac-System which is held and manipulated by an articulated robot. KW - Laser beam welding KW - Laser welding with mobile vacuum PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612068 DO - https://doi.org/10.1016/j.procir.2024.08.145 VL - 124 SP - 418 EP - 423 PB - Elsevier BV AN - OPUS4-61206 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gumenyuk, Andrey A1 - Bakir, Nasim A1 - Rethmeier, Michael T1 - Two-colour thermography for measurement of temperature distribution in laser beam welding N2 - Solidification cracking is a frequently observed phenomenon in laser beam welding of austenitic stainless steels and other metallic alloys. Characterisation of cracking susceptibility requires knowledge of the precise and spatially resolved temperature distribution near the solidification front in the welding process. Thermography is a standard tool that provides a qualitative estimate of the 2D temperature field. The general disadvantage of this method is its dependence on the emission characteristics of the measured object. For welding applications, these can vary significantly in the temperature range above and below the melting temperature. For this purpose, we have developed a thermography-based measurement technique using a SWIR camera system in combination with two narrow bandpass filters that use the principle of two-wavelength pyrometry to estimate absolute temperature values. This technique was used to determine the temperature distributions and gradients near the solidification front of laser-welded austenitic steel. The results were validated by other measurements. KW - Laser beam welding KW - Two-colour thermography KW - Solidification cracking PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-612070 DO - https://doi.org/10.1016/j.procir.2024.08.155 VL - 124 SP - 468 EP - 471 PB - Elsevier BV AN - OPUS4-61207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Keke A1 - El-Sari, Bassel A1 - Olfert, Viktoria A1 - Wang, Zhuoqun A1 - Biegler, Max A1 - Rethmeier, Michael A1 - Meschut, Gerson T1 - Expulsion prevention in resistance spot welding of dissimilar joints with ultra-high strength steel: An analysis of the mechanism and effect of preheating current N2 - The widespread adoption of ultra-high strength steels, due to their high bulk resistivity, intensifies expulsion issues in resistance spot welding (RSW), deteriorating both the spot weld and surface quality. This study presents a novel approach to prevent expulsion by employing a preheating current. Through characteristic analysis of joint formation under critical welding current, the importance of plastic material encapsulation around the weld nugget (plastic shell) at high temperatures in preventing expulsion is highlighted. To evaluate the effect of preheating on the plastic shell and understand its mechanism in expulsion prevention, a two-dimensional welding simulation model for dissimilar ultra-high strength steel joints was established. The results showed that optimal preheating enhances the thickness of the plastic shell, improving its ability to encapsulate the weld nugget during the primary welding phase, thereby diminishing expulsion risks. Experimental validation confirmed that by employing the optimal preheating current, the maximum nugget diameter was enhanced to 9.42 mm, marking an increase of 13.4 % and extending the weldable current range by 27.5 %. Under quasi-static cross-tensile loading, joints with preheating demonstrated a 7.9 % enhancement in maximum load-bearing capacity compared to joints without preheating, showing a reproducible and complete pull-out failure mode within the heat-affected zone. This study offers a prevention method based on underlying mechanisms, providing a new perspective for future research on welding parameter optimization with the aim of expulsion prevention. KW - Resistance spot welding KW - Finite element modelling KW - Preheating KW - Weldable current range KW - Ultra-high strength steel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621719 DO - https://doi.org/10.1016/j.jmapro.2024.06.034 VL - 124 SP - 489 EP - 502 PB - Elsevier Ltd. AN - OPUS4-62171 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Uhlmann, Eckart A1 - Polte, Julian A1 - Fasselt, Janek Maria A1 - Müller, Vinzenz A1 - Klötzer-Freese, Christian A1 - Kleba-Ehrhardt, Rafael A1 - Biegler, Max A1 - Rethmeier, Michael T1 - A Comparative Evaluation of Powder Characteristics of Recycled Material from Bronze Grinding Chips for Additive Manufacturing N2 - In the manufacturing process of ship propellers, large quantities of grinding chips are generated. These grinding chips result from the finishing of the blade surfaces after the primary casting process of the propeller. The aim of this study was to investigate and compare different preparation processes used to produce chip powders with sufficient powder quality for the additive manufacturing process of directed energy deposition. The preparation of the samples was performed through different sieving, milling and re-melting processes. For the characterization of the prepared samples, powder analysis according to relevant industry standards was carried out. It was found that the re-melting processes result in superior powder quality for additive manufacturing in terms of particle size, morphology, and flowability. For some characteristics, the powder exhibits even better properties than those of commercial powders. Furthermore, the powder properties of the milled samples demonstrate a promising potential for u KW - Grinding chips KW - Comminution KW - Aluminium bronze KW - Additive manufacturing KW - Recycling KW - Sustainability PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621696 DO - https://doi.org/10.3390/ma17143396 VL - 17 IS - 14 SP - 1 EP - 15 PB - MDPI AG AN - OPUS4-62169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Raute, Julius A1 - Beret, Alexander A1 - Biegler, Max A1 - Rethmeier, Michael T1 - Life cycle assessment in additive manufacturing of copper alloys—comparison between laser and electron beam N2 - Additive manufacturing is becoming increasingly important for industrial production. In this context, directed energy deposition processes are in demand to achieve high deposition rates. In addition to the well-known laser-based processes, the electron beam has also reached industrial market maturity. The wire electron beam additive manufacturing offers advantages in the processing of copper materials, for example. In the literature, the higher energy efficiency and the resulting improvement in the carbon footprint of the electron beam are highlighted. However, there is a lack of practical studies with measurement data to quantify the potential of the technology. In this work, a comparative life cycle assessment between wire electron beam additive manufacturing (DED-EB) and laser powder additive manufacturing (DED-LB) is carried out. This involves determining the resources for manufacturing, producing a test component using both processes, and measuring the entire energy consumption. The environmental impact is then estimated using the factors global warming potential (GWP100), photochemical ozone creation potential (POCP), acidification potential (AP), and eutrophication potential (EP). It can be seen that wire electron beam additive manufacturing is characterized by a significantly lower energy requirement. In addition, the use of wire ensures greater resource efficiency, which leads to overall better life cycle assessment results. KW - Life cycle assessment (LCA) KW - Additive manufacturing KW - Directed energy deposition KW - Wire electron beam additive manufacturing KW - Copper alloys PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621705 DO - https://doi.org/10.1007/s40194-024-01856-9 SP - 3169 EP - 3176 PB - Springer Science and Business Media LLC AN - OPUS4-62170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marquardt, R. A1 - Biegler, M. A1 - Rethmeier, Michael T1 - Functionally graded material for improved wear resistance manufactured by directed energy deposition N2 - Protecting components against wear and corrosion is a common way to improve their lifetime. This can be achieved by coating them with a hardfacing material. Common coatings consist of materials such as tungsten carbide or cobalt-chromium alloys, also known as Stellite. Hardfacing materials can be deposited by welding methods like plasma welding or laser cladding. The discrete change of the base material to the hardfacing layer can lead to cracks and chipping. Studies showed a reduced risk of cracking when a functionally graded material is used to create a smooth transition between the base and the hardfacing. Gradings from austenitic steel to cobalt-chromium alloys are already known in the literature. However, there is no knowledge about austenitic- ferritic duplex steels as base material. Therefore, this study aims to demonstrate the feasibility of a functionally graded material from duplex steel to cobalt-chromium alloy with a new approach. By using powder-based directed energy deposition, a graded material with smooth material transition is manufactured additively. Cracking and porosity are examined through metallography. Microhardness measurements as well as the analysis of the chemical composition by energy dispersive X-ray spectroscopy and X-ray fluorescence are used to validate the build-up strategy. KW - Additive manufacturing KW - Functionally graded material KW - Functionally graded additive manufacturing KW - Directed energy deposition KW - Laser metal deposition PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621683 DO - https://doi.org/10.1007/s40964-024-00879-4 SP - 1 EP - 6 PB - Springer Science and Business Media LLC AN - OPUS4-62168 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Assessment of keyhole stability in laser beam welding with external magnetic field using numerical simulation N2 - The challenge of understanding the physical mechanisms behind porosity reduction by a magnetic field during laser beam welding (LBW) is partly due to the difficulty in quantitatively evaluating keyhole stability. The commonly used index, such as keyhole depth, is typically one-dimensional, which is insufficient to capture the dynamic and three-dimensional fluctuations of the keyhole. In this paper, by utilizing a 3D multiphysical model of LBW with magnetic field, a novel keyhole geometry reconstruction algorithm has been developed to describe the keyhole profile and its fluctuation in a statistical manner to evaluate keyhole stability quantitatively. An equivalent diameter is proposed in this algorithm to reduce the irregularity of the keyhole geometry. The calculation results indicate that the time-averaged keyhole shape over 300 ms in the LBWof steel is conical, regardless of the application of an external magnetic field, which provides a more representative shape. Meanwhile, it is observed from the statistical aspect that the keyhole diameter becomes smaller, except the top part, under the influence of the magnetic field. The standard deviation of the equivalent diameter can be used as a physical variable to assess the keyhole stability quantitatively. The application of an external magnetic field can produce a noticeable reduction of the standard deviation of the equivalent diameter, namely, stabilizing the keyhole during LBW of steel. However, the different contribution from the keyhole stability affected by a magnetic field in suppressing porosity is different with materials. T2 - International Congress of Applications of Lasers & Electro-Optics 2024 CY - Los Angeles, CA, USA DA - 04.11.2024 KW - Deep penetration laser beam welding KW - Numerical simulation KW - Keyhole shape KW - Keyhole stability KW - Magnetic field PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614984 DO - https://doi.org/10.2351/7.0001528 VL - 36 IS - 4 SP - 1 EP - 7 PB - AIP Publishing CY - Melville, NY AN - OPUS4-61498 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Parametric study of the laser energy absorption in high-power laser beam welding N2 - Laser energy absorption on the keyhole wall is decisive for the thermodynamic behavior and the resultant weld properties in the high-power laser beam welding process. However, its highly transient nature on a microsecond scale makes the quantitative analysis challenging. In this paper, the influence of the relevant welding parameters on laser energy absorption is studied statistically by utilizing multiphysical modeling, in which the three-dimensional transient keyhole dynamics and thermo-fluid flow are calculated. A dynamic mesh adaption technique and a localized level-set-based ray-tracing method are employed to improve the model accuracy further. The results show that the focus position has a remarkable effect on the time-averaged laser absorption, and in contrast, the laser energy distribution regime is only slightly influenced by the welding speed in the studied parameter range (1.5–3.0 m/min). The absorption ratio of the laser energy on the keyhole front wall decreases with increasing welding speed and increases with upward-moving focus positions. The comparison between the calculated results and the experimental measurements ensures the validity of the proposed model. T2 - International Congress of Applications of Lasers & Electro-Optics 2024 CY - Los Angeles, CA, USA DA - 03.11.2024 KW - Laser beam welding KW - Laser energy absorption KW - Weld pool KW - Parametric study KW - Multiphysics modeling PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616070 DO - https://doi.org/10.2351/7.0001537 SN - 1042-346X VL - 36 IS - 3 SP - 1 EP - 6 PB - AIP Publishing AN - OPUS4-61607 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Putra, Stephen Nugraha A1 - Meng, Xiangmeng A1 - Yang, Fan A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical study on the temperature characteristic of material absorptivity and its significance in high-power laser beam welding N2 - The absorptivity of metallic materials plays an important role in high-power laser beam welding. It affects the amount of absorbed laser power leading to the heating and melting of the surfaces to be joined and is highly dependent on the temperature. Nonetheless, this key characteristic is often ignored in numerical simulations and an empirical parameter determined by trial-and-error approaches is rather implemented to calibrate the results. In the present work, the temperature dependence of laser absorption is included in a three-dimensional multiphase numerical model considering the coupled fluid flow and heat transfer. The calculated laser absorption is determined by the temperature-dependent material properties, laser characteristics, and incident angle of the laser beam. It is found that the temperature dependence of the laser absorption is crucial for accurately determining the keyhole and weld pool geometries, which is validated by experimental measurements using 304 austenitic steel. T2 - 13th CIRP Conference on Photonic Technologies [LANE 2024] CY - Fürth, Germany DA - 15.09.2024 KW - Laser beam welding KW - Temperature dependent absorption KW - Weld pool KW - Keyhole dynamics KW - Numerical modelling PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616146 DO - https://doi.org/10.1016/j.procir.2024.08.179 VL - 124 SP - 585 EP - 589 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-61614 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Fan A1 - Meng, Xiangmeng A1 - Putra, Stephen Nugraha A1 - Bachmann, Marcel A1 - Rethmeier, Michael T1 - Numerical studies of magnetohydrodynamic technology in suppressing process porosity during laser beam welding N2 - The magnetohydrodynamic (MHD) technology is employed to mitigate the porosity problem during partial penetration laser beam welding (LBW) of 10 mm thick aluminum alloy. The effectiveness and universal applicability of the MHD technology in reducing porosity during the LBW process are confirmed by a reduction in the porosity ratio of more than 89%. A transient 3D multi-physical model coupled with the MHD effect has been developed to investigate the suppression mechanism of process porosity. Due to the influence of Lorentz force, there is an obvious change in the weld pool length. This change widens the escaping channel of bubbles escaping from the weld pool. The application of an oscillating magnetic field changes the fluid flow pattern noticeably, whose influence on the formation of porosity defects is highly complicated and nonlinear. T2 - CIRP Conference on Photonic Technologies [LANE 2024] CY - Fürth, Germany DA - 15.09.2024 KW - Laser beam welding KW - Aluminum alloy KW - Process Porosity KW - Porosity suppression KW - Magnetohydrodynamic technology PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-616053 DO - https://doi.org/10.1016/j.procir.2024.08.175 VL - 124 SP - 565 EP - 569 PB - Elsevier B.V. AN - OPUS4-61605 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Seitz, Georg A1 - Bantle, Patrick A1 - Biegler, Max A1 - Elsner, Beatrix A. M. A1 - Rethmeier, Michael T1 - An Inherent Strain Method Using Progressive Element Activation for Fast Distortion Calculation in Directed Energy Deposition N2 - The finite element analysis (FEA) simulation of directed energy deposition (DED) processes offers many potential cost savings during the build job optimization process, through, e.g., distortion predictions. However, the biggest challenge is the long calculation time, frequently exceeding the actual build time. One way of simplifying the simulation with the aim of reducing the calculation times is the inherent strain method. While this method is already used commercially in the simulation of powder bed-based processes and conventional welding technologies, its use in DED is still the subject of research. In this work, an inverse determination of an inherent strain is carried out on a 20-layer-high, single-track-wide wall, common theories are reviewed, and an approach based on thermal strain is introduced. As a result, the calculation time could be reduced by 83% and the accuracy remained at 92%. KW - Inherent strain method KW - Simulation KW - Finite element analysis KW - Directed energy deposition KW - Additive manufacturing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622595 DO - https://doi.org/10.3390/met14121338 SN - 2075-4701 VL - 14 IS - 12 SP - 1 EP - 12 PB - MDPI AN - OPUS4-62259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yang, Keke A1 - Sowada, Matthias A1 - Olfert, Viktoria A1 - Seitz, Georg A1 - Schreiber, Vincent A1 - Heitmann, Marcel A1 - Hein, David A1 - Biegler, Max A1 - Jüttner, Sven A1 - Rethmeier, Michael A1 - Meschut, Gerson T1 - Influence of liquid metal embrittlement on the failure behavior of dissimilar spot welds with advanced high-strength steel: A component study N2 - This study investigates the effects of liquid metal embrittlement (LME) cracks on the mechanical performance of resistance spot-welded joints in zinc-coated advanced high-strength steel (AHSS) at the component level. To this end, a novel component-level test specimen featuring a hat and L-shaped profile was developed to identify critical failure points under three-point bending loads. Load-bearing capacity tests were subsequently conducted under both quasi-static and impact loading conditions, specifically targeting LME cracks with an average depth reaching 63.6% of the sheet thickness. By monitoring the surface strain of spot welds affected by LME cracks, the study visualizes stress concentration effects at the crack tips and traces the propagation of these cracks into the base material, which ultimately leads to material tearing and joint failure. The findings reveal that the effect of LME cracks in reducing load-bearing capacity is more pronounced under impact loading than under quasi-static loading, highlighting a previously underexplored aspect of LME behavior under impact loading. Specifically, the peak load decreased by 3.9% and 10.8%, while energy absorption declined by 52.2% and 78.3% under quasistatic and impact loading, respectively. KW - Liquid metal embrittlement KW - Resistance spot welding KW - Impact loading KW - Crack propagation KW - Advanced high-strength steel PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621727 DO - https://doi.org/10.1016/j.jmrt.2024.11.166 VL - 33 SP - 8321 EP - 8328 PB - Elsevier B.V. AN - OPUS4-62172 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lemke, Josefine A1 - Höfemann, Matthias A1 - Biegler, Max A1 - Rethmeier, Michael T1 - Process strategies for optimizing the cooling behaviour of laser-welded Tailor Welded Blanks made of advanced high strength steels (AHSS) N2 - AHSS with 1000 MPa tensile strength show promising properties for the use in Tailor Welded Blanks (TWBs) to locally strengthen car body parts. Challenges in laser beam welding of the sheets are hardness-drops and -peaks in the heat-affected zone (HAZ) and weld, which cause risks during cold-forming. This happens due to rapid cooling caused by laser welding. A numerical approach aiming for slower cooling rates in the weld region is presented in this article. Laser welded sheets served as reference for setting up a process simulation. Models for pre-heating and a coaxial setup with power split were set up. A correlation between cooling-rate and hardness in the joining zone was established and applied to the modelled strategy. Splitting the power led to a slightly narrower weld seam and experimental pre-heating of the sheets to 600 °C could lower total seam hardening. It achieved a homogenization of the fusion zone. KW - AHSS KW - Laser welding KW - Tailor Welded Blanks KW - Hardness KW - FEM KW - HAZ PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622324 DO - https://doi.org/10.1016/j.procir.2024.08.176 VL - 124 SP - 570 EP - 573 PB - Elsevier B.V. AN - OPUS4-62232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Castanon-Jano, Laura A1 - Palomera-Obregon, Paula A1 - Lázaro, Mariano A1 - Blanco-Fernandez, Elena A1 - Blasón Gonzalez, Sergio T1 - Enhancing sustainability in polymer 3D printing via fusion filament fabrication through integration of by-products in powder form: Mechanical and thermal characterization N2 - FFF (fused filament fabrication) is a type of 3D printing that utilizes filament for part creation. This study proposes using by-products or waste to replace part of the plastic in FFF filament, reducing environmental impact. The aim is to maintain a simple manufacturing process involving extrusion on a single-screw desktop machine followed by printing. The plastic matrix comprises polylactic acid (PLA) and polyethylene glycol (PETG), with added powdered by-products: seashells, car glass and mill scale (metal). Additives will be incorporated at 10% and 20% by weight, with two grain sizes: up to 0.09 mm and up to 0.018 mm. Mechanical tests (tensile, flexural and hardness) and thermal characterization tests will be conducted. Findings suggest adding 10%w powder of any variety to PETG increases tensile strength up to 48%, with metal powder (mill scale) showing the highest enhancement, even at 20%w, resulting in a 41% increase. Conversely, adding powder to PLA worsens mechanical properties without stiffening the material; instead, the elastic modulus decreases. Metal grain size has minimal impact, with grain sizes lower than 0.09 mm optimal for PLA. Thermal conductivity in polymers blended with powder additives is lower than in virgin polymers, likely due to air void formation, supported by density and microscopic evaluations. This research underscores the potential of utilizing waste materials with a simple FFF filament production to enhance sustainability in 3D printing practices. KW - 3D printing KW - FFF KW - PLA KW - PETg KW - Metal powder KW - Glass powder KW - Seashells powder KW - Tension KW - Bending KW - Thermal properties KW - Sustainability KW - Plastic consumption PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635027 DO - https://doi.org/10.1007/s00170-024-13635-3 SN - 0268-3768 VL - 133 IS - 3-4 SP - 1251 EP - 1269 PB - Springer CY - London AN - OPUS4-63502 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Monavari, Mahshid A1 - Sohrabi, Razieh A1 - Motasadizadeh, Hamidreza A1 - Monavari, Mehran A1 - Fatahi, Yousef A1 - Ejarestaghi, Negin Mousavi A1 - Fuentes-Chandia, Miguel A1 - Leal-Egaña, Aldo A1 - Akrami, Mohammad A1 - Homaeigohar, Shahin T1 - Levofloxacin loaded poly (ethylene oxide)-chitosan/quercetin loaded poly (D,L-lactide-co-glycolide) core-shell electrospun nanofibers for burn wound healing N2 - This study developed a new burn wound dressing based on core-shell nanofibers that co-deliver antibiotic and antioxidant drugs. For this purpose, poly(ethylene oxide) (PEO)-chitosan (CS)/poly(D,L-lactide-co-glycolide) (PLGA) core-shell nanofibers were fabricated through co-axial electrospinning technique. Antibiotic levofloxacin (LEV) and antioxidant quercetin (QS) were incorporated into the core and shell parts of PEO-CS/PLGA nanofibers, respectively. The drugs could bond to the polymer chains through hydrogen bonding, leading to their steady release for 168 h. An in vitro drug release study showed a burst effect followed by sustained release of LEV and QS from the nanofibers due to the Fickian diffusion. The NIH 3T3 fibroblast cell viability of the drug loaded core-shell nanofibers was comparable to that in the control (tissue culture polystyrene) implying biocompatibility of the nanofibers and their cell supportive role. However, there was no significant difference in cell viability between the drug loaded and drug free core-shell nanofibers. According to in vivo experiments, PEO-CS-LEV/PLGA-QS core-shell nanofibers could accelerate the healing process of a burn wound compared to a sterile gauze. Thanks to the synergistic therapeutic effect of LEV and QS, a significantly higher wound closure rate was recorded for the drug loaded core-shell nanofibrous dressing than the drug free nanofibers and control. Conclusively, PEO-CS-LEV/PLGA-QS core-shell nanofibers were shown to be a promising wound healing material that could drive the healing cascade through local co-delivery of LEV and QS to burn wounds. KW - Core-shell nanofiber KW - Co-axial electrospinning KW - Drug delivery KW - Burn wound KW - Wound healing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635115 DO - https://doi.org/10.3389/fbioe.2024.1352717 SN - 2296-4185 VL - 12 SP - 1 EP - 14 PB - Frontiers Media CY - Lausanne AN - OPUS4-63511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Erxleben, Kjell A1 - Richter, Tim A1 - Schröpfer, Dirk A1 - Mente, Tobias A1 - Michael, Thomas T1 - Local mechanical properties of dissimilar metal TIG welded joints of CoCrFeMnNi high entropy alloy and AISI 304 austenitic steel N2 - Multiple principal element alloys encompass the well-known high entropy alloys (HEA). The alloy system represents a new class of materials consisting of at least three alloying elements, each containing 5 to 35 at.%. Thus, this alloying concept differs fundamentally from conventional materials such as steel or nickel alloys. For this purpose, the alloying elements are specifically selected, the microstructures are adjusted in a single-phase and, in some cases, multi-phase manner. In particular, conflicting goals, such as the trade-off between strength and ductility in conventional steels, are overcome. However, in the last 20 years, the focus has been on material synthesis. With the increase in available material quantities, the focus is now on processing issues such as joining and welding processes. The weldability of HEAs has received very little attention so far. The experience with dissimilar metal welds is completely lacking but is essential for the application of these materials in combination with conventional materials. The present study presents comprehensive experimental results on the weldability of an equimolar CoCrFeMnNi-HEA in cold-rolled and heat-treated condition, which was joined by tungsten inert gas welding to an austenitic steel AISI 304. The mechanical properties of the dissimilar metal welds were characterized by cross-weld tensile samples, whereas the local deformation in the weld of the different welding zones was measured by digital image correlation. In accordance with the respective initial HEA condition (cold-rolled vs. heat-treated), the local strain behavior was divergent and influenced the global mechanical properties of both DMW types. Nonetheless, the experiments provided proof in principle of the weldability for dissimilar joints of the CoCrFeMnNi-HEA welded to conventional materials like austenitic stainless steels ensuring a corresponding capability for mechanical loading. This allows further considerations on the application of these innovative materials. KW - TIG welding KW - High-entropy alloys KW - Mechanical properties KW - Dissimilar metal weld PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595775 DO - https://doi.org/10.1007/s40194-024-01718-4 SN - 0043-2288 SP - 1 EP - 11 PB - Springer Science and Business Media LLC AN - OPUS4-59577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Salari, Farid A1 - Zocca, Andrea A1 - Bosetti, Paolo A1 - Hlaváček, Petr A1 - Italiano, Antonino A1 - Gobbin, Filippo A1 - Colombo, Paolo A1 - Kühne, Hans-Carsten A1 - Sglavo, Vincenzo M. T1 - Powder-bed 3D printing by selective activation of magnesium phosphate cement: Determining significant processing parameters and their effect on mechanical strength N2 - The present work addresses powder bed binder jetting additive manufacturing by selective magnesium phosphate cement activation. Despite the potential of this technology to aid the digitalization of the construction industry, the effect of processing parameters on the mechanical performance of printed materials has not yet been studied to generate a guideline for the further development of the technology. Statistical methodologies were used to screen the effect of four printing process parameters (printing speed, layer thickness, raster angle, and build direction on flexural and compressive strength). As the exploited technology works with constant fluid pressure, the physical interpretation of the effect of each factor can be considered taking into account the interactions between the binder materials in the powder bed. Analysis of variance (ANOVA) indicated that printing speed and layer thickness significantly affect mechanical performances. Furthermore, the layout of samples for the printing process is preferable to be parallel the printhead movement. An anisotropic behavior was observed, and the samples subjected to compressive forces parallel to the layer plane possessed lower strength values. This effect can be interpreted as a result of a weak area of low density in between layers, leading to a pronounced delamination under compression. Even though the strength of the printed material is not suitable for a structural concrete, it can be marginally improved by design of experiment and optimized for non-structural applications, such as for porous artificial stone. Design of experiment coupled with ANOVA methods can be used in the future to support the development of novel material mixtures, thus expanding the fields of application of this novel additive manufacturing technology. KW - Concrete 3D-printing KW - Particle-bed binder jetting KW - Design of experiment PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601654 DO - https://doi.org/10.1016/j.oceram.2024.100609 VL - 18 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-60165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bernardy, Christopher A1 - Habib, Abdel Karim A1 - Kluge, Martin A1 - Schalau, Bernd A1 - Schulze, Marcel A1 - Kant, Hanjo A1 - Orchini, Alessandro ED - Di Benedetto, Almerinda ED - Portarapillo, Maria T1 - Investigation of the thermal radiation from hydrogen jet flames N2 - For industrial applications dealing with hydrogen, the definition of safety distances and the assessment of possible hazards emanating from releases is mandatory. Since hydrogen is usually stored and transported under pressure, one scenario to be considered is the momentum driven release of hydrogen from a leakage with subsequent ignition. In this scenario, the emitted heat radiation from the resulting jet flame to the surroundings has to be determined to define adequate safety distances. For hydrocarbon flames, different jet flame models are available to assess the hazards resulting from an ignited jet release. Since hydrogen flames differ from hydrocarbon flames in their combustion behavior, it has to be checked if these models are also applicable for hydrogen. To evaluate the accuracy of these models for hydrogen jet flames, tests at real-scale are carried out at the BAM Test Site for Technical Safety (BAM-TTS). Herein, the flame geometry and the heat radiation at defined locations in the surroundings are recorded for varying release parameters such as leakage diameter (currently up to 30 mm), release pressure (currently up to max. 250 bar) and mass flow (up to max. 0.5 kg/s). The challenge here is the characterization of the flame geometry in an open environment and its impact on the thermal radiation. Existing heat radiation data from the literature are mostly based on unsteady outflow conditions. For a better comparability with the steady state jet flame models, the experiments presented here are focused on ensuring a constant mass flow over the release duration to obtain a (quasi) stationary jet flame. In addition, stationary outflow tests with hydrocarbons (methane) were also carried out, which are intended to serve as reference tests for checking flame models based on hydrocarbon data. T2 - 15th International Symposium on Hazards, Prevention and Mitigation of Industrial Explosions (ISHPMIE) CY - Neaples, Italy DA - 10.06.2024 KW - Hydrogen KW - Release KW - Jet flame KW - Thermal radiation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-605107 DO - https://doi.org/10.5281/zenodo.12515710 VL - 2024 SP - 1322 EP - 1333 PB - Zenodo CY - Geneva AN - OPUS4-60510 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Balscheit, Hagen A1 - Geißler, Peter A1 - Cuéllar, Pablo A1 - Basedau, Frank A1 - Baeßler, Matthias T1 - Large-scale field tests on plastic pile tip failure upon monopile installation N2 - Large-diameter monopiles are the most common foundation structures for offshore wind turbines. One relevant failure mode during installation is plastic failure of the pile tip which may increase progressively during further driving (pile tip buckling; extrusion buckling). This paper presents the details and results of a large-scale field-test campaign with dynamic pile installation for the validation and calibration of different numerical approaches concerning pile-tip buckling phenomena. The phenomenology of observed pile-tip failures is here described in detail and a first quantitative approach is evaluated based on the field-test data. As the number of new projects continues to grow and the necessity to construct wind farms in challenging terrain increases, such field data-sets will become increasingly relevant. KW - Monopile KW - Offshore Windenergy KW - Pfahlfußbeulen KW - Pile Tip Buckling KW - Reference Tests PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611651 DO - https://doi.org/10.1016/j.oceaneng.2024.119322 VL - 313 SP - 1 EP - 14 PB - Elsevier B.V. AN - OPUS4-61165 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohr, Gunther A1 - Chaudry, Mohsin Ali A1 - Scheuschner, Nils A1 - Blasón Gonzalez, Sergio A1 - Madia, Mauro A1 - Hilgenberg, Kai T1 - Thermal history transfer from complex components to representative test specimens in laser powder bed fusion N2 - Additively manufactured components are characterized by heterogeneous mechanical properties due to variations of the microstructure, flaws and residual stresses resulting from the inhomogeneous fabrication process. The large number of influencing factors poses a further challenge in understanding the correlation between material properties, process parameters and component geometry. Therefore, the qualification of components based on witness specimens produced within the same job is questionable. This work aims to present a new strategy for the characterization of PBF-LB/M components based on representative specimens. The key assumption is the feasibility of a transfer of the thermal history from a component to a specimen. It is assumed that similar material properties are determined for components and specimens produced adopting a similar thermal history. After the definition of a region of interest in the component, a combination of thermal analyses by means of finite elements and in-situ experimental determination of the thermal history through infrared thermography is used to produce test coupons with a similar thermal history. The effectiveness of the procedure is demonstrated on a pressure vessel for applications in the chemical industry. KW - Additive manufacturing KW - Heat accumulation KW - Thermal history KW - In situ monitoring KW - Process simulation KW - Representative specimens PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602651 DO - https://doi.org/10.1007/s40964-024-00689-8 SN - 2363-9512 SN - 2363-9520 SP - 1 EP - 16 PB - Springer CY - Cham, Switzerland AN - OPUS4-60265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nourinejhad Zarghani, S. A1 - Monavari, Mehran A1 - Nourinejhad Zarghani, A. A1 - Nouri, S. A1 - Ehlers, J. A1 - Hamacher, J. A1 - Bandte, M. A1 - Büttner, C. T1 - Quantifying plant viruses: Evolution from bioassay to infectivity dilution curves along the model of tobamoviruses N2 - This review describes the development of the bioassay as a means of quantifying plant viruses, with particular attention to tobamovirus. It delves into various models used to establish a correlation between virus particle concentration and the number of induced local lesions (the infectivity dilution curve), including the Poisson, Furumoto and Mickey, Kleczkowski, Growth curve, and modified Poisson models. The parameters of each model are described, and their application or performance in the context of the tobacco mosaic virus is explored. This overview highlights the enduring value of the infectivity dilution curve in tobamovirus quantification, providing valuable insights for researchers or practitioners of bioassays and theoreticians of modeling. KW - Local lesion KW - qRT-PCR KW - Nicotiana KW - ToBRFV KW - TMV KW - CGMMV KW - Disinfection KW - Modeling PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-630142 DO - https://doi.org/10.3390/v16030440 SN - 1999-4915 VL - 16 IS - 3 SP - 1 EP - 14 PB - MDPI CY - Basel AN - OPUS4-63014 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Oster, Simon A1 - Scheuschner, Nils A1 - Chand, Keerthana A1 - Altenburg, Simon T1 - Local porosity prediction in metal powder bed fusion using in-situ thermography: A comparative study of machine learning techniques N2 - The formation of flaws such as internal porosity in parts produced by Metal-based Powder Bed Fusion with Laser Beam (PBF-LB/M) significantly hinders its broader industrial application, as porosity can potentially lead to part failure. Addressing this issue, this study explores the efficacy of in-situ thermography, particularly short-wave infrared thermography, for detecting and predicting porosity during manufacturing. This technique is capable of monitoring the part’s thermal history which is closely connected to the flaw formation process. Recent advancements in Machine Learning (ML) have been increasingly leveraged for porosity prediction in PBF-LB/M. However, previous research primarily focused on global rather than localized porosity prediction which simplified the complex prediction task. Thereby, the opportunity to correlate the predicted flaw position with expected part strain to judge the severity of the flaw for part performance is neglected. This study aims to bridge this gap by studying the potential of SWIR thermography for predicting local porosity levels using regression models. The models are trained on data from two identical HAYNES®282® specimens. We compare the effectiveness of feature-based and raw data-based models in predicting different porosity types and examine the importance of input data in porosity prediction. We show that models trained on SWIR thermogram data can identify systematic trends in local flaw formation. This is demonstrated for forced flaw formation using process parameter shifts and, moreover, for randomly formed flaws in the specimen bulk. Furthermore, we identify features of high importance for the prediction of lack-of-fusion and keyhole porosity from SWIR monitoring data. KW - PBF-LB/M KW - In situ monitoring KW - Thermography KW - Additive Manufacturing KW - Process monitoring KW - Porosity prediction KW - Machine Learning KW - Feature extraction PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621798 DO - https://doi.org/10.1016/j.addma.2024.104502 SN - 2214-7810 VL - 95 SP - 1 EP - 17 PB - Elsevier B.V. AN - OPUS4-62179 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kromm, Arne A1 - Thomas, Maximilian A1 - Kannengießer, Thomas A1 - Gibmeier, Jens T1 - On the interpretation of Varestraint and Transvarestraint hot cracking test results N2 - The Varestraint test and its variant Transvarestraint are one of the most widely used techniques for evaluating a material solidification cracking sensitivity during welding. The result of such tests is a crack length which is proportional to the material’s cracking susceptibility. Nevertheless, the welding and load parameters can unintentionally influence the crack length, which in some cases can distort the material evaluation. An approach is described as to how these effects can be assessed with the aid of a digital crack analysis. The crack lengths are compared position-dependently with their possible propagation due to the weld pool movement during continuous loading. The index derived from this can be used by the operator to evaluate his test parameters. In addition, a comparison of the results of different Varestraint setups is made possible. Alongside experimental results, a numerical sensitivity analysis is presented on how individual welding and loading parameters can affect the crack lengths. KW - Varestraint test KW - Solidification cracking KW - Weldability PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595089 DO - https://doi.org/10.1007/s40194-024-01706-8 SN - 0043-2288 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59508 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Griesche, Axel A1 - Nietzke, Jonathan A1 - Kannengießer, Thomas T1 - In situ measurement of hydrogen concentration in steel using laser‑induced breakdown spectroscopy (LIBS) N2 - The ISO 3690 standard “Determination of hydrogen content in arc weld metal” requires a thermal activation of the diffusible hydrogen in a piece of weld metal for the subsequent ex situ concentration measurement by carrier gas hot extraction CGHE or thermal desorption spectroscopy (TCD). Laser-induced breakdown spectroscopy (LIBS) offers a time and spatially resolved, almost non-destructive, in situ measurement of hydrogen at surfaces without sample preparation. We measured hydrogen in steels, which were charged either electrochemically or by high-pressure hydrogen gas, and compared the results. Further, the feasibility of quantitative hydrogen line scan measurements with LIBS was demonstrated by measuring hydrogen at water jet cut surfaces. The hydrogen concentrations measured with the help of LIBS were compared with CGHE measurements. It was observed that hydrogen can be reliably measured with LIBS for concentrations larger than 2 wt.-ppm. The maximum hydrogen concentration achieved using electrochemical charging was 85.1 ppm. The results show that LIBS is a promising technique for time- and spatially resolved measurements of hydrogen in steels. T2 - IIW Annual Assembly 2023 CY - Singapore KW - LIBS KW - Hydrogen measurement KW - Welding KW - Stainless steel KW - Diffusible hydrogen PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593664 DO - https://doi.org/10.1007/s40194-023-01677-2 SP - 1 EP - 9 PB - Springer AN - OPUS4-59366 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wandtke, Karsten ED - Becker, Amadeus ED - Schröpfer, Dirk ED - Kromm, Arne ED - Kannengießer, Thomas ED - Scharf-Wildenhain, R. ED - Hälsig, A. ED - Hensel, J. T1 - Residual Stress Evolution during Slot Milling for Repair Welding and Wire Arc Additive Manufacturing of High-Strength Steel Components N2 - High-strength steels offer potential for weight optimization due to reduced wall thicknesses in modern constructions. Additive manufacturing processes such as Wire Arc Additive Manufacturing (WAAM) enable the resource-efficient production of structures. In the case of defects occurring in weld seams orWAAM components due to unstable process conditions, the economical solution is local gouging or machining and repair welding. It is important to understand the effects of machining steps on the multiaxial stress state in conjunction with the design-related shrinkage restraints. Research into how welding and slot milling of welds andWAAM structures affects residual stresses is still lacking. For this reason, component-related investigations with high-strength steels with yield strengths ≥790 MPa are carried out in our research. In-situ digital image correlation (DIC) and ex-situ X-ray diffraction (XRD) were used to analyze the stresses and strains induced on specimens during and after milling. The systematic analyses revealed a significant interaction of the stiffness and microstructure of the specimens with the initial residual stresses induced by welding. Subsequent repair welds can result in significantly higher residual stresses. KW - High strength steels KW - Additive manufacturing KW - Residual stress KW - Repair welding KW - Ditigtal image correlation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-593515 DO - https://doi.org/10.3390/met14010082 VL - 14 IS - 1 SP - 1 EP - 11 PB - MDPI CY - Basel AN - OPUS4-59351 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Witte, Julien A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Stresses in repair welding of high-strength steels—part 1: restraint and cold cracking risk N2 - AbstractThe sustainable and resource-efficient production of wind energy plants requires the use of modern high-strength fine-grain structural steels. This applies to both foundation and erection structures, like mobile or ship cranes. During the assembly of steel structures, unacceptable defects can occasionally be found in the weld area. In most cases, the economical solution would be local thermal gouging of the affected areas and re-welding. Due to the high shrinkage restraint of the joint groove in the overall structure, the superposition of global and local welding-induced stresses may lead to crack formation and component failure, particularly in interaction with the degradation of the microstructure and mechanical properties of high-strength steels during the repair process. However, manufacturers hardly have any information about these issues and there is a lack of recommendations and guidelines to take these safety-relevant aspects into account in adequate repair concepts. The aim of this research is to derive recommendations for repair concepts appropriate to the stresses and materials involved providing a basis for standards and guidelines to avoid cold cracking, damage and expensive reworking especially for high-strength steels. Part 1 of this study involves systematic investigations of influences of shrinkage restraint during repair welding of two high-strength steels S500MLO for offshore application and S960QL for mobile crane structures. The quantification of the shrinkage restraint of repair weld joints was achieved by means of experimental and numerical restraint intensity analysis. In welding experiments with self-restrained slot specimens, restraint intensity and introduction of hydrogen via the welding arc using anti spatter spray were varied systematically to analyse the effect on welding result, residual stresses and cold cracking. It could be shown that increasing restraint intensities result in significantly higher transverse residual stress levels. In the case of hydrogen introduction S500MLO showed no cold cracking independent of the restraint conditions. However, S960QL was found to be considerably cold cracking sensitive if hydrogen is introduced. With increasing restraint intensity length and number of cold cracks increases significantly. Part 2 [1] of this study is focussed on microstructure and residual stresses due to gouging and stress optimization via adequate heat control parameters in repair welding. KW - Metals and Alloys KW - Mechanical Engineering KW - Mechanics of Materials PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595212 DO - https://doi.org/10.1007/s40194-024-01691-y SN - 0043-2288 SP - 1 EP - 13 PB - Springer Science and Business Media LLC AN - OPUS4-59521 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Nina A1 - Rhode, Michael A1 - Kannengießer, Thomas T1 - Influence of microalloying on precipitation behavior and notch impact toughness of welded high‑strength structural steels N2 - Microalloying elements such as Nb and Ti are essential to increase the strength of quenched and tempered high-strength low alloy (HSLA) structural steels with nominal yield strength ≥ 690 MPa and their welded joints. Standards such as EN 10025–6 only specify limits or ranges for chemical composition, which leads to variations in specific compositions between steel manufacturers. These standards do not address the mechanical properties of the material, and even small variations in alloy content can significantly affect these properties. This makes it difficult to predict the weldability and integrity of welded joints, with potential problems such as softening or excessive hardening of the heat-affected zone (HAZ). To understand these metallurgical effects, previous studies have investigated different microalloying routes with varying Ti and Nb contents using test alloys. The high-strength quenched and tempered fine-grained structural steel S690QL is the basic grade regarding chemical composition and heat treatment. To evaluate weldability, three-layer welds were made using high-performance MAG welding. HAZ formation was investigated, and critical microstructural areas were identified, focusing on phase transformations during cooling and metallurgical precipitation behavior. Isothermal thermodynamic calculations for different precipitations were also carried out. Mechanical properties, especially Charpy notch impact toughness, were evaluated to understand the influence of different microalloys on the microstructure of the HAZ and mechanical properties. KW - High-strength structural steel KW - Gas metal arc welding KW - HAZ-softening KW - Notch impact toughness KW - Microalloying influences KW - Thermodynamic simulation PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608548 DO - https://doi.org/10.1007/s40194-024-01827-0 SN - 0043-2288 SP - 1 EP - 13 PB - Springer AN - OPUS4-60854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Gornushkin, Igor B. A1 - Griesche, Axel A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker T1 - In situ chemical analysis of duplex stainless steel weld by laser induced breakdown spectroscopy N2 - The high corrosion resistance and good mechanical properties of duplex stainless steel (DSS) are due to its special chemical composition, which is a balanced phase ratio of ferrite (α) and austenite (γ). Many industrial applications require the integration of DSS components. For this, Gas tungsten arc welding (GTAW) is an excellent choice, as it allows an automated operation with high reproducibility. However, when the weld pool solidifies, critical ratios of α- and γ- phases can occur, which lead to solidification cracking, increased susceptibility to corrosion, and a decrease in ductility and critical strength. Previous studies have shown that these defects can be caused by the accumulation of manganese and chromium in the heat affected zone (HAZ), requiring ongoing monitoring of this accumulation. A suitable method for such monitoring is laser-induced breakdown spectroscopy (LIBS), which can be used in two operating modes: calibration using standard reference samples and calibration-free. Unlike conventional quantitative LIBS measurements, which require reference samples to generate a calibration curve, calibration-free LIBS (CF-LIBS) allows chemical compositions to be determined solely from the emission spectrum of the plasma. Numerous publications show that CF-LIBS is a fast and efficient analytical method for the quantitative analysis of metal samples. In this work, CF-LIBS is applied to spectra obtained during GTAW DSS welding and the result is compared with those obtained by PLS analysis. A good correlation was found between both types of analysis, demonstrating the suitability of the CF-LIBS method for this application. The CF-LIBS method has a significant advantage over conventional LIBS due to the rapid in situ measurement of concentrations of major alloying elements without calibration procedure. This, combined with fast feedback and appropriate adjustment of welding parameters, helps prevent welding defects. KW - Duplex stainless steels KW - In situ measurement KW - LIBS KW - GMAW PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-597940 DO - https://doi.org/10.1016/j.sab.2024.106899 SN - 0584-8547 VL - 214 SP - 1 EP - 7 PB - Elsevier B.V. AN - OPUS4-59794 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Welding KW - Phase balance KW - Microscopy KW - Microstructure PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618777 DO - https://doi.org/10.1007/s40194-024-01878-3 SN - 1878-6669 VL - 69 IS - 1 SP - 31 EP - 45 PB - Springer CY - Berlin AN - OPUS4-61877 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Quackatz, Lukas A1 - Westin, Elin Marianne A1 - Griesche, Axel A1 - Kromm, Arne A1 - Kannengießer, Thomas A1 - Treutler, Kai A1 - Wesling, Volker A1 - Wessman, Sten T1 - Assessing ferrite content in duplex stainless weld metal: WRC ‘92 predictions vs. practical measurements N2 - AbstractThe weldability of stainless steels is largely controlled by the chemical composition, and alloys with ferritic or ferritic-austenitic solidification show the highest resistance to hot cracking. As the resulting phase balance also affects the final properties, it may be beneficial to both foresee and measure the weld metal ferrite content. The WRC ‘92 constitution diagram is currently the most accurate prediction tool available, but it does not take the cooling rate into consideration and the precision may be less accurate for stainless steels with high ferrite numbers (FNs). This study aims to assess the reliability of the WRC ‘92 diagram for weld metals with FN  50. The chemical composition was altered through gas tungsten arc welding (GTAW) of UNS S32205 with ER347 filler wire that had been coated using physical vapor deposition (PVD) with either niobium (Nb), copper (Cu), nickel (Ni), manganese (Mn), carbon (C), or silicon (Si). The actual ferrite content was evaluated using image analysis, FeriteScope and X-ray diffraction (XRD). While predictions from the WRC ‘92 diagram were deemed acceptable for Ni, Si, and Mn, notable deviations were observed for Nb, Cu, and C. The FeriteScope exhibited a consistent trend with image analysis, albeit with slightly higher FN values, wider scatter, and the conversion factor from FN to vol% is open for discussion. The lowest accuracy and largest spread were obtained using non-contact XRD, rendering it unsuitable for ferrite measurements of welds. These findings underscore the need for improved prediction tools and appropriate measurement methods for assessing ferrite content in duplex weld metals. KW - Duplex stainless steel KW - Phase fraction prediction KW - WRC diagram PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-623682 DO - https://doi.org/10.1007/s40194-024-01878-3 VL - 69 SP - 31 EP - 45 PB - Springer Science and Business Media LLC AN - OPUS4-62368 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Giese, Marcel A1 - Gräbner, Maraike A1 - Schröpfer, Dirk A1 - Treutler, Kai A1 - Lorenz, Svenja A1 - Kannengießer, Thomas A1 - Wesling, Volker T1 - Alloy modification and ultrasonic-assisted milling of wear-resistant alloys with defined surfaces N2 - The reduction of CO2 emissions is closely linked to the development of highly efficient and economical steel components in plant and process engineering. To withstand the high combined corrosive, tribological, thermal, and mechanical stresses, wear-resistant coatings tailored to the application and steel grade are used. In addition to the increasing demand to substitute conventional cobalt alloys with nickel alloys, there is also a growing need for defined or functional surfaces of high integrity. Due to high tool wear, milling operations required to produce the complex geometries of the components are often not economically feasible for SMEs. By means of alloy modification of the filler metals for nickel-based plasma build-up welded wear-resistant coatings and by the use of innovative ultrasonic-assisted milling processes more favourable machinability shall be achieved without reducing the wear protection potential. In this paper, the influence of the microstructure and precipitation morphology adjusted by means of alloy modification on the machinability is investigated. This is done based on a wear protection alloy NiCrMoSiFeB (trade name: Colmonoy 56 PTA) typically used for screw machines, which substitutes conventional CoCr alloys (Stellite). Metallurgical investigations and in-situ measurements of occurring process forces and temperatures at the tool cutting edge during milling as well as subsequent investigations of tool wear and surface integrity allow a detailed analysis and correlation between microstructural properties and machinability. For the cast samples, a clear change in the microstructure and hardness can be seen through the addition of Al, Ti, or Nb. These differences lead to an improvement in the machining process for Nb. Al and Ti cause long-needled or star-shaped precipitations and hardness increases, which lead to higher cutting forces and increased tool wear. KW - Cladding KW - Wear resistant alloys KW - Alloy modification KW - Post-processing KW - Ultrasonic assisted milling KW - Renewable energy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622918 DO - https://doi.org/10.1007/s40194-024-01786-6 SN - 1878-6669 VL - 68 SP - 2567 EP - 2575 PB - Springer Science and Business Media LLC CY - Berlin ; Heidelberg AN - OPUS4-62291 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rabin, Ira A1 - Gordon, Nehemia A1 - Calvillo, Nelson T1 - Coloured Ruling Lines in a Fourteenth-Century Ashkenazi Torah Scroll N2 - Rabbinic halakhah required that Torah scrolls be written with relief ruling, horizontal and vertical lines scored into the writing surface. Coloured ruling with plummet or ink would make a Torah scroll invalid for liturgical use. Ruling lines on some leather fragments of early Oriental Torah scrolls give the impression of being produced with plummet or ink but may be the result of dust in the furrows of relief ruling. Erfurt 9, a fourteenth-century Ashkenazi Torah scroll, has coloured ruling, which is partial secondary re-ruling, on 13 of the 34 surviving sheets, perhaps added when the original relief ruling was difficult to see. The coloured ruling in Erfurt 9 is brown, giving it the visual appearance of iron-gall ink. However, XRF tests showed that the only meaningful metallic component in the coloured ruling was lead (Pb). Lead plummet ruling tends to have a greyish appearance. Black specks under near infrared light are consistent with minium, a lead-based red ink that can turn brown when it degrades. Partial secondary re-ruling added with minium to the original relief ruling comes as a surprise as it would have rendered Erfurt 9 unfit for liturgical use. KW - Hebrew Manuscripts KW - Ruling Lines KW - Coloured Ink PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-628531 DO - https://doi.org/10.25592/uhhfdm.17169 SN - 2410-0951 VL - 10 SP - 9 EP - 32 AN - OPUS4-62853 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wätzold, Florian A1 - Popiela, Bartosz A1 - Mayer, Jonas T1 - Methodology for AI-Based Search Strategy of Scientific Papers: Exemplary Search for Hybrid and Battery Electric Vehicles in the Semantic Scholar Database N2 - The rapid development of artificial intelligence (AI) has significantly enhanced productivity, particularly in repetitive tasks. In the scientific domain, literature review stands out as a key area where AI-based tools can be effectively applied. This study presents a methodology for developing a search strategy for systematic reviews using AI tools. The Semantic Scholar database served as the foundation for the search process. The methodology was tested by searching for scientific papers related to batteries and hydrogen vehicles with the aim of enabling an evaluation for their potential applications. An extensive list of vehicles and their operational environments based on international standards and literature reviews was defined and used as the main input for the exemplary search. The AI-supported search yielded approximately 60,000 results, which were subjected to an initial relevance assessment. For the relevant papers, a neighbourhood analysis based on citation and reference networks was conducted. The final selection of papers, covering the period from 2013 to 2023, included 713 papers assessed after the initial review. An extensive discussion of the results is provided, including their categorisation based on search terms, publication years, and cluster analysis of powertrains, as well as operational environments of the vehicles involved. This case study illustrates the effectiveness of the proposed methodology and serves as a starting point for future research. The results demonstrate the potential of AI-based tools to enhance productivity when searching for scientific papers. KW - Search strategy KW - Methodology KW - Artificial intelligence KW - Literature review KW - Battery electric vehicles KW - Hydrogen-powered vehicles PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622012 DO - https://doi.org/10.3390/publications12040049 VL - 12 IS - 4 SP - 1 EP - 16 PB - MDPI CY - Basel, Switzerland AN - OPUS4-62201 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Roveda, Ilaria A1 - Serrano-Munoz, Itziar A1 - Haubrich, Jan A1 - Requena, Guillermo A1 - Madia, Mauro T1 - Investigation on the fatigue strength of AlSi10Mg fabricated by PBF-LB/M and subjected to low temperature heat treatments N2 - This work provides an investigation of the influence of low temperature heat treatments on the fatigue behavior of a PBF-LB AlSi10Mg alloy. Fatigue specimens are produced in form of round bars on a build platform preheated at 200 ◦C. The specimens have been tested in three different conditions: as-built, and after heat treatments at 265 ◦C for 1 h and 300 ◦C for 2 h. Prior to the fatigue testing, the defect distribution is analyzed by means of micro computed tomography. Subsequently, the peak over threshold method is successfully applied to provide a prediction of the size of killer defect. The defect population was of gas porosity type. No clear improvement of the fatigue performance is observed after the heat treatments. The fatigue strength predicted using fracture mechanics-based approaches is in good agreement with the experimental data. Among the studied approaches, short crack models provided the most conservative predictions. KW - PBF-LB/M AlSi10Mg KW - Fatigue strength KW - Defects KW - Kitagawa-Takahashi Diagram KW - Short Crack Models PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607071 DO - https://doi.org/10.1016/j.matdes.2024.113170 SN - 0264-1275 VL - 244 SP - 1 EP - 12 PB - Elsevier Ltd. AN - OPUS4-60707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lozano-Martín, D. A1 - Pazoki, F. A1 - Kipphardt, Heinrich A1 - Khanipour, P. A1 - Tuma, Dirk A1 - Horillo, A. A1 - Chamorro, C. R. T1 - Thermodynamic (p, ρ, T) characterization of a reference high-calorific natural gas mixture when hydrogen is added up to 20 % (mol/mol) N2 - The injection of hydrogen into the natural-gas grid is an alternative during the process of a gradual decarbonization of the heat and power supply. When dealing with hydrogen-enriched natural gas mixtures, the performance of the reference equations of state habitually used for natural gas should be validated by using high-precision experimental thermophysical data from multicomponent reference mixtures prepared with the lowest possible uncertainty in composition. In this work, we present experimental density data for an 11-compound high-calorific (hydrogen-free) natural gas mixture and for two derived hydrogen-enriched natural gas mixtures prepared by adding (10 and 20) mol-% of hydrogen to the original standard natural gas mixture. The three mixtures were prepared gravimetrically according to ISO 6142–1 for maximum precision in their composition and thus qualify for reference materials. A single-sinker densimeter was used to determine the density of the mixtures from (250–350) K and up to 20 MPa. The experimental density results of this work have been compared to the densities calculated by three different reference equations of state for natural gas related mixtures: the AGA8-DC92 EoS, the GERG-2008 EoS, and an improved version of the GERG-2008 EoS. While relative deviations of the experimental density data for the hydrogen-free natural gas mixture are always within the claimed uncertainty of the three considered equations of state, larger deviations can be observed for the hydrogen-enriched natural gas mixtures from any of the three equations of state, especially for the lowest temperature and the highest pressures. KW - Hydrogen-enriched natural gas KW - Single-sinker densimeter KW - High-pressure density KW - Equations of state PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-604742 DO - https://doi.org/10.1016/j.ijhydene.2024.05.028 SN - 0360-3199 VL - 70 SP - 118 EP - 135 PB - Elsevier BV CY - Amsterdam AN - OPUS4-60474 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ghata, Anupama A1 - Bernges, Tim A1 - Maus, Oliver A1 - Wankmiller, Björn A1 - Naik, Aakash A1 - Bustamante, Joana A1 - Gaultois, Michael W. A1 - Delaire, Olivier A1 - Hansen, Michael Ryan A1 - George, Janine A1 - Zeier, Wolfgang G. T1 - Exploring the Thermal and Ionic Transport of Cu+ Conducting Argyrodite Cu7PSe6 N2 - AbstractUnderstanding the origin of low thermal conductivities in ionic conductors is essential for improving their thermoelectric efficiency, although accompanying high ionic conduction may present challenges for maintaining thermoelectric device integrity. This study investigates the thermal and ionic transport in Cu7PSe6, aiming to elucidate their fundamental origins and correlation with the structural and dynamic properties. Through a comprehensive approach including various characterization techniques and computational analyses, it is demonstrated that the low thermal conductivity in Cu7PSe6 arises from structural complexity, variations in bond strengths, and high lattice anharmonicity, leading to pronounced diffuson transport of heat and fast ionic conduction. It is found that upon increasing the temperature, the ionic conductivity increases significantly in Cu7PSe6, whereas the thermal conductivity remains nearly constant, revealing no direct correlation between ionic and thermal transport. This absence of direct influence suggests innovative design strategies in thermoelectric applications to enhance stability by diminishing ionic conduction, while maintaining low thermal conductivity, thereby linking the domains of solid‐state ionics and thermoelectrics. Thus, this study attempts to clarify the fundamental principles governing thermal and ionic transport in Cu+‐superionic conductors, similar to recent findings in Ag+ argyrodites. KW - Thermoelectrics KW - Phonons KW - Chemically Complex Materials KW - DFT KW - Bonding Analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608866 DO - https://doi.org/10.1002/aenm.202402039 SP - 1 EP - 9 PB - Wiley AN - OPUS4-60886 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naik, Aakash A1 - Ueltzen, Katharina A1 - Ertural, Christina A1 - Jackson, Adam J. A1 - George, Janine T1 - LobsterPy: A package to automatically analyze LOBSTERruns N2 - The LOBSTER (Deringer et al., 2011;Maintz et al., 2013 ,2016 ;Nelson et al., 2020 ) software aids in extracting quantum-chemical bonding information from materials by projecting the plane-wave based wave functions from density functional theory (DFT) onto an atomic orbital basis. LobsterEnv, a module implemented in pymatgen (Ong et al., 2013) by some of the authors of this package, facilitates the use of quantum-chemical bonding information obtained from LOBSTER calculations to identify neighbors and coordination environments. LobsterPy is a Python package that offers a set of convenient tools to further analyze and summarize the LobsterEnv outputs in the form of JSONs that are easy to interpret and process. These tools enable the estimation of (anti) bonding contributions, generation of textual descriptions, and visualization of LOBSTER computation results. Since its first release, both LobsterPy and LobsterEnv capabilities have been extended significantly. Unlike earlier versions, which could only automatically analyze Crystal Orbital Hamilton Populations (COHPs) (Dronskowski & Blöchl, 1993), both can now also analyze Crystal Orbital Overlap Populations (COOP) (Hughbanks & Hoffmann, 1983) and Crystal Orbital Bond Index (COBI) (Müller et al., 2021). Extracting the information about the most important orbitals contributing to the bonds is optional, and users can enable it as needed. Additionally, bonding-based features for machinelearning (ML) studies can be engineered via the sub-packages “featurize” and “structuregraphs”. Alongside its Python interface, it also provides an easy-to-use command line interface (CLI) that runs automatic analysis of the computations and generates a summary of results and publication-ready figures. LobsterPy has been used to produce the results in Ngo et al. (2023), Chen et al. (2024), Naik et al. (2023), and it is also part of Atomate2 (2023) bonding analysis workflow for generating bonding analysis data in a format compatible with the Materials Project (Jain et al., 2013) API. KW - Materials Science KW - Automation KW - Bonding Analysis KW - Materials Properties PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595809 DO - https://doi.org/10.21105/joss.06286 VL - 9 IS - 94 SP - 1 EP - 4 PB - The Open Journal AN - OPUS4-59580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Musyanovych, A. A1 - Grimmer, Christoph A1 - Sadak, A. E. A1 - Heßling, L. A1 - Lüdicke, M. A1 - Bilsel, M. A1 - Horn, Wolfgang A1 - Richter, Matthias T1 - Polymer Capsules with Volatile Organic Compounds as Reference Materials for Controlled Emission N2 - Encapsulation of volatile organic compounds (VOCs) that could evaporate at a defined rate is of immense interest for application in emission reference materials (ERMs). Polyurethane/polyurea microcapsules with various VOC active ingredients (limonene, pinene, and toluene) were successfully produced by interfacial polymerization with Shirasu porous glass membrane emulsification in a size range between 10 and 50 μm. The effect of surfactant, VOC, monomer(s) type, and ratio has a great effect on the formulation process and morphology of capsules. The type of VOC played a significant role in the encapsulation efficiency. Due to the difference in vapor pressure and VOC/water interfacial tension, the formulation for encapsulation was optimized for each individual VOC. Furthermore, to achieve effective stability of the large droplets/capsules, a combination of ionic and nonionic surfactants was used. Optical and scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were used to characterize the optimized microcapsules. The results showed that the obtained microcapsules exhibited a spherical shape and core–shell morphology and featured characteristic urethane-urea bonds. The amount of encapsulated VOC ranges between 54 and 7 wt %. The emission tests were performed with the help of the emission test chamber procedure (EN 16516). The limonene-loaded polyurethane/polyurea microcapsules show a change in emission rate of less than 10% within 14 days and can be considered as a potential candidate for use as an ERM. KW - Polymer microcapsules KW - Membrane emulsification KW - Polyaddition KW - Volatile organic compound (VOC) KW - Emission testing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-619227 DO - https://doi.org/10.1021/acsami.4c12826 SN - 1944-8252 VL - 16 IS - 50 SP - 69999 EP - 70009 PB - ACS AN - OPUS4-61922 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Winkler, Nicolas P. A1 - Kotlyar, O. A1 - Schaffernicht, E. A1 - Matsukura, H. A1 - Ishida, H. A1 - Neumann, Patrick P. A1 - Lilienthal, A. J. T1 - Super-resolution for Gas Distribution Mapping N2 - Gas Distribution Mapping (GDM) is a valuable tool for monitoring the distribution of gases in a wide range of applications, including environmental monitoring, emergency response, and industrial safety. While GDM is actively researched in the scope of gas-sensitive mobile robots (Mobile Robot Olfaction), there is a potential for broader applications utilizing sensor networks. This study aims to address the lack of deep learning approaches in GDM and explore their potential for improved mapping of gas distributions. In this paper, we introduce Gas Distribution Decoder (GDD), a learning-based GDM method. GDD is a deep neural network for spatial interpolation between sparsely distributed sensor measurements that was trained on an extensive data set of realistic-shaped synthetic gas plumes based on actual airflow measurements. As access to ground truth representations of gas distributions remains a challenge in GDM research, we make our data sets, along with our models, publicly available. We test and compare GDD with state-of-the-art models on synthetic and real-world data. Our findings demonstrate that GDD significantly outperforms existing models, demonstrating a 35% improvement in accuracy on synthetic data when measured using the Root Mean Squared Error over the entire distribution map. Notably, GDD appears to have superior capabilities in reconstructing the edges and characteristic shapes of gas plumes compared to traditional models. These potentials offer new possibilities for more accurate and efficient environmental monitoring, and we hope to inspire other researchers to explore learning-based GDM. KW - Gas distribution mapping KW - Spatial interpolation KW - Sensor networks KW - Deep learning PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607786 DO - https://doi.org/10.1016/j.snb.2024.136267 SN - 0925-4005 VL - 419 SP - 1 EP - 12 PB - Elsevier B.V. AN - OPUS4-60778 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Marschall, Niklas A1 - Meinel, Dietmar A1 - Böhning, Martin T1 - Relation of craze to crack length during slow crack growth phenomena in high‐density polyethylene N2 - The craze‐crack mechanism occurring in high‐density polyethylene (HDPE) causing slow crack growth and environmental stress cracking is investigated in detail with respect to the relation of crack length and the related craze zone. This is essential for the understanding of the resulting features of the formed fracture surface and their interpretation in the context of the transition from crack propagation to ductile shear deformation. It turns out that an already formed craze zone does not inevitably result in formation of a propagating crack, but could also undergo ductile failure. For the examination, the full notch creep test (FNCT) was employed with a subsequent advanced fracture surface analysis that was performed using various imaging techniques: light microscopy, laser scanning microscopy, scanning electron microscopy, and X‐ray micro computed tomography scan. FNCT specimens were progressively damaged for increasing durations under standard test conditions applying Arkopal, the standard surfactant solution, and biodiesel as test media were used to analyze the stepwise growth of cracks and crazes. From considerations based on well‐established fracture mechanics approaches, a theoretical correlation between the length of the actual crack and the length of the preceding craze zone was established that could be evidenced and affirmed by FNCT fracture surface analysis. Moreover, the yield strength of a HDPE material exposed to a certain medium as detected by a classic tensile test was found to be the crucial value of true stress to induce the transition from crack propagation due to the craze‐crack mechanism to shear deformation during FNCT measurements. Highlights - Progress of crack formation in high‐density polyethylene is analyzed by different imaging techniques - Determined growth rates depend on distinction between craze zone and crack - The ratio of the present crack to the anteceding craze zone is validated theoretically - The transition from crack propagation to ductile shear deformation is identified - An already formed craze zone may still fail by ductile mechanisms KW - Craze-crack mechanism KW - Environmental stress cracking (ESC) KW - Full notch creep test (FNCT) KW - Laser scanning microscopy (LSM) KW - Slow crack growth (SCG) KW - X-ray computed tomography (CT) PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601831 DO - https://doi.org/10.1002/pen.26698 SN - 1548-2634 VL - 64 IS - 6 SP - 2387 EP - 2403 PB - Wiley AN - OPUS4-60183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Mosane Razavi, Negar A1 - Bojdys, M. J. A1 - Forster, A. B. A1 - Budd, P. M. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM‑1 and a Phosphinine Containing Covalent Organic Framework N2 - Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller. As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%. KW - Polymers of Intrinsic Microporosity KW - Nanocomposites PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595031 DO - https://doi.org/10.1021/acs.macromol.3c02419 SN - 0024-9297 VL - 57 IS - 4 SP - 1829 EP - 1845 PB - ACS Publications AN - OPUS4-59503 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Emamverdi, Farnaz A1 - Huang, J. A1 - Szymoniak, Paulina A1 - Bojdys, M. J. A1 - Böhning, Martin A1 - Schönhals, Andreas T1 - Structure and molecular mobility of phosphinine-based covalent organic frameworks – glass transition of amorphous COFs N2 - Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy. Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer–Emmett–Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials. KW - Covalent Organic frameworks PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-596770 DO - https://doi.org/10.1039/d3ma01123b SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-59677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tang, Chi-Long A1 - Seeger, Stefan T1 - Measurement of sub-4 nm particle emission from FFF-3D printing with the TSI Nano Enhancer and the Airmodus Particle Size Magnifier N2 - The emission of ultrafine particles from small desktop Fused Filament Fabrication (FFF) 3D printers has been frequently investigated in the past years. However, the vast majority of FFF emission and exposure studies have not considered the possible occurrence of particles below the typical detection limit of Condensation Particle Counters and could have systematically underestimated the total particle emission as well as the related exposure risks. Therefore, we comparatively measured particle number concentrations and size distributions of sub-4 nm particles with two commercially available diethylene glycol-based instruments – the TSI 3757 Nano Enhancer and the Airmodus A10 Particle Size Magnifier. Both instruments were evaluated for their suitability of measuring FFF-3D printing emissions in the sub-4 nm size range while operated as a particle counter or as a particle size spectrometer. For particle counting, both instruments match best when the Airmodus system was adjusted to a cut-off of 1.5 nm. For size spectroscopy, both instruments show limitations due to either the fast dynamics or rather low levels of particle emissions from FFF-3D printing in this range. The effects are discussed in detail in this article. The findings could be used to implement sub-4 nm particle measurement in future emission or exposure studies, but also for the development of standard test protocols for FFF-3D printing emissions. KW - Air pollution KW - Ultrafine particles KW - Sub-4nm particles KW - FFF-3D printing KW - Emission testing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595952 DO - https://doi.org/10.1080/02786826.2024.2320430 SN - 0278-6826 VL - 58 IS - 6 SP - 644 EP - 656 PB - Taylor & Francis CY - London AN - OPUS4-59595 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gugin, Nikita A1 - Yusenko, Kirill A1 - King, Andrew A1 - Meyer, Klas A1 - Al-Sabbagh, Dominik A1 - Villajos Collado, José Antonio A1 - Emmerling, Franziska T1 - Lighting up industrial mechanochemistry: Real-time in situ monitoring of reactive extrusion using energy-dispersive X-ray diffraction N2 - Mechanochemistry is an environmentally friendly synthetic approach that enables the sustainable production of a wide range of chemicals while reducing or eliminating the need for solvents. Reactive extrusion aims to move mechanochemistry from its conventional gram-scale batch reactions, typically performed in laboratory ball mills, to a continuous, large-scale process. Meeting this challenge requires in situ monitoring techniques to gain insights into reactive extrusion and its underlying processes. While the effectiveness of in situ Raman spectroscopy in providing molecular-level information has been demonstrated, our study uses energy-dispersive X-ray diffraction to monitor reactive extrusion in real time at the crystalline level. Our results provide previously unavailable control over the reactive extrusion process, promoting its perception as an industrially feasible green alternative to traditional solvent-based syntheses. KW - Mechanochemistry KW - Reactive extrusion KW - Green chemistry KW - In situ studies KW - Time-resolved in situ KW - TRIS KW - Synchrotron radiation KW - Scalable synthesis KW - Solid-state reactions KW - Reaction mechanisms PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613969 DO - https://doi.org/10.1016/j.chempr.2024.07.033 VL - 10 IS - 11 SP - 1 EP - 16 PB - Elsevier B.V. AN - OPUS4-61396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mohring, Wencke A1 - Karafiludis, Stephanos A1 - Manzoni, Anna Maria A1 - Laplanche, G. A1 - Schneider, M. A1 - Stephan-Scherb, Christiane T1 - High-Temperature Corrosion of High- and Medium-Entropy Alloys CrMnFeCoNi and CrCoNi Exposed to a Multi-Oxidant Atmosphere H2O–O2–SO2 N2 - AbstractThe high-temperature corrosion behaviors of the equimolar CrCoNi medium-entropy alloy and CrMnFeCoNi high-entropy alloy were studied in a gas atmosphere consisting of a volumetric mixture of 10% H2O, 2% O2, 0.5% SO2, and 87.5% Ar at 800 °C for up to 96 h. Both alloys were initially single-phase fcc with a mean grain size of ~ 50 μm and a homogeneous chemical composition. The oxide layer thickness of CrMnFeCoNi increased linearly with exposure time while it remained constant at ~ 1 μm for CrCoNi. A Cr2O3 layer and minor amounts of (Co,Ni)Cr2O4 developed on the latter while three oxide layers were detected on the former, i.e., a thin and continuous chromium rich oxide layer at the oxide/alloy interface, a dense (Mn,Cr)3O4 layer in the center and a thick and porous layer of Mn3O4 and MnSO4 at the gas/oxide interface. Additionally, a few metal sulfides were observed in the CrMnFeCoNi matrix. These results were found to be in reasonable agreement with thermodynamic calculations. KW - high entropy alloys KW - corrosion KW - oxidation KW - scanning electron microscopy KW - sulfidation KW - CrMnFeCoNi PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594189 DO - https://doi.org/10.1007/s44210-023-00026-8 SP - 1 EP - 17 PB - Springer Science and Business Media LLC AN - OPUS4-59418 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, Yijuan A1 - Gawlitza, Kornelia A1 - Valderrey, Virginia A1 - Bhattacharya, Biswajit A1 - Rurack, Knut T1 - Ratiometric Molecularly Imprinted Particle Probes for Reliable Fluorescence Signaling of Carboxylate-Containing Molecules N2 - In addition to sensitivity, selectivity, and portability, chemical sensing systems must generate reliable signals and offer modular configurability to address various small molecule targets, particularly in environmental applications. We present a versatile, modular strategy utilizing ratiometric molecularly imprinted particle probes based on BODIPY indicators and dyes for recognition and internal referencing. Our approach employs polystyrene core particles doped with a red fluorescent BODIPY as an internal standard, providing built-in reference for environmental influences. A molecularly imprinted polymer (MIP) recognition shell, incorporating a green-fluorescent BODIPY indicator monomer with a thiourea binding site for carboxylate containing analytes, is grafted from the core particles in the presence of the analyte as the template. The dual-fluorescent MIP probe detects fexofenadine as the model analyte with a change in green emission signal referenced against a stable red signal, achieving a detection limit of 0.13 μM and a broad dynamic range from 0.16 μM to 1.2 mM, with good discrimination against other antibiotics in acetonitrile. By selecting a versatile dye scaffold and recognition element, this approach can be extended to other carboxylate-containing analytes and/or wavelength combinations, potentially serving as a robust multiplexing platform. KW - Core-shell particles KW - Molecular imprinting KW - Pharmaceutical contaminants KW - Self-referenced measurements KW - Fluorescence PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-609385 DO - https://doi.org/10.1021/acsami.4c09990 SP - 1 EP - 13 PB - American Chemical Society (ACS) AN - OPUS4-60938 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Russo, Francesco F. A1 - Nowatzky, Yannek A1 - Jaeger, Carsten A1 - Parr, Maria K. A1 - Benner, Philipp A1 - Muth, Thilo A1 - Lisec, Jan T1 - Machine learning methods for compound annotation in non‐targeted mass spectrometry—A brief overview of fingerprinting, in silico fragmentation and de novo methods N2 - Non‐targeted screenings (NTS) are essential tools in different fields, such as forensics, health and environmental sciences. NTSs often employ mass spectrometry (MS) methods due to their high throughput and sensitivity in comparison to, for example, nuclear magnetic resonance–based methods. As the identification of mass spectral signals, called annotation, is labour intensive, it has been used for developing supporting tools based on machine learning (ML). However, both the diversity of mass spectral signals and the sheer quantity of different ML tools developed for compound annotation present a challenge for researchers in maintaining a comprehensive overview of the field.In this work, we illustrate which ML‐based methods are available for compound annotation in non‐targeted MS experiments and provide a nuanced comparison of the ML models used in MS data analysis, unravelling their unique features and performance metrics. Through this overview we support researchers to judiciously apply these tools in their daily research. This review also offers a detailed exploration of methods and datasets to show gaps in current methods, and promising target areas, offering a starting point for developers intending to improve existing methodologies. KW - Mass Spectrometry KW - Spectra annotation KW - Machine learning PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608732 DO - https://doi.org/10.1002/rcm.9876 VL - 38 IS - 20 SP - 1 EP - 15 PB - Wiley AN - OPUS4-60873 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Peter, Elisa K. A1 - Jaeger, Carsten A1 - Lisec, Jan A1 - Peters, R. Sven A1 - Mourot, Rey A1 - Rossel, Pamela E. A1 - Tranter, Martyn A1 - Anesio, Alexandre M. A1 - Benning, Liane G. T1 - Endometabolic profiling of pigmented glacier ice algae: the impact of sample processing N2 - Introduction Glacier ice algae, mainly Ancylonema alaskanum and Ancylonema nordenskiöldi, bloom on Greenland Ice Sheet bare ice surfaces. They significantly decrease surface albedo due to their purple-brown pigmentation, thus increasing melt. Little is known about their metabolic adaptation and factors controlling algal growth dynamics and pigment formation. A challenge in obtaining such data is the necessity of melting samples, which delays preservation and introduces bias to metabolomic analysis. There is a need to evaluate the physiological response of algae to melting and establish consistent sample processing strategies for metabolomics of ice microbial communities. Objectives To address the impact of sample melting procedure on metabolic characterization and establish a processing and analytical workflow for endometabolic profiling of glacier ice algae. Methods We employed untargeted, high-resolution mass spectrometry and tested the effect of sample melt temperature (10, 15, 20 °C) and processing delay (up to 49 h) on the metabolome and lipidome, and complemented this approach with cell counts (FlowCam), photophysiological analysis (PAM) and diversity characterization. Results and Conclusion We putatively identified 804 metabolites, with glycerolipids, glycerophospholipids and fatty acyls being the most prominent superclasses ( 50% of identified metabolites). Among the polar metabolome, carbohydrates and amino acid-derivatives were the most abundant. We show that 8% of the metabolome is affected by melt duration, with a pronounced decrease in betaine membrane lipids and pigment precursors, and an increase in phospholipids. Controlled fast melting at 10 °C resulted in the highest consistency, and is our recommendation for future supraglacial metabolomics studies. KW - Metabolic profiling KW - Mass Spectrometry KW - Ice algae PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607921 DO - https://doi.org/10.1007/s11306-024-02147-6 VL - 20 IS - 5 SP - 1 EP - 15 PB - Springer Science and Business Media LLC AN - OPUS4-60792 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tobias, Charlie A1 - López-Puertollano, Daniel A1 - Abad-Somovilla, Antonio A1 - Mercader, J. V. A1 - Abad-Fuentes, A. A1 - Rurack, Knut T1 - Development of Simple and Rapid Bead-Based Cytometric Immunoassays Using Superparamagnetic Hybrid Core−Shell Microparticles N2 - Flow cytometry-based immunoassays are valuable in biomedical research and clinical applications due to their high throughput and multianalyte capability, but their adoption in areas such as food safety and environmental monitoring is limited by long assay times and complex workflows. Rapid, simplified bead-based cytometric immunoassays are needed to make these methods viable for point-of-need applications, especially with the increasing accessibility of miniaturized cytometers. This work introduces superparamagnetic hybrid polystyrene-silica core−shell microparticles as promising alternatives to conventional polymer beads in competitive cytometric immunoassays. These beads, featuring high specificity, sensitivity, and excellent handling capabilities via magnetic separation, were evaluated with three different antibodies and binding methods, showing variations in signal intensity based on the antibody and its attachment method. The optimal performance was achieved through a secondary antibody binding approach, providing strong and consistent signals with minimal uncertainty. The optimized protocol made it possible to achieve a detection limit of 0.025 nM in a total assay time of only 15 min and was successfully used to detect ochratoxin A (OTA) in raw flour samples. This work highlights the potential of these beads as versatile tools for flow cytometry-based immunoassays, with significant implications for food safety, animal health, environmental monitoring, and clinical diagnostics. KW - Immunoassays KW - Bead-based KW - Core-shell particles KW - Cytometry KW - Mycotoxins PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610593 DO - https://doi.org/10.1021/acsmeasuresciau.4c00038 SP - 1 EP - 11 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-61059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gadelmeier, C. A1 - Agudo Jácome, Leonardo A1 - Suárez Ocano, Patricia A1 - Glatzel, U. T1 - Effect of stacking fault energy (SFE) of single crystal, equiatomic CrCoNi and Cantor alloy on creep resistance N2 - Compared to mechanisms like solid solution strengthening, the stacking fault energy (SFE) should be considered as a further factor that influences the material properties. The effect of SFE of alloys or individual elements on strength and resistance can vary considerably. In the high-temperature regime above 700 ◦C, there are still significant gaps in the knowledge about the effect of the SFE on the mechanical properties of single-phase alloys. The effect of SFE on creep resistance of two face-entered cubic equiatomic medium and high entropy alloys, CrCoNi and CrMnFeCoNi, respectively, is evaluated to fill parts of these gaps. Using the Bridgman solidification process, the alloys were produced as single crystals and crept under vacuum at 700 ◦C up to 1100 ◦C. This work shows a significant impact of the lower SFE of CrCoNi on the creep behavior compared to the results of previous investigations of CrMnFeCoNi. The creep resistance of the former is higher over the complete temperature range. At very high temperatures, the strengthening effect of the stacking faults is significantly present. The formation of tetragonal stacking faults and extended dislocation nodes can be identified as the reason for this effect. KW - Medium entropy alloy KW - MEA KW - HEA KW - Single crystal KW - CrCoNi PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-602620 DO - https://doi.org/10.1016/j.msea.2024.146779 SN - 0921-5093 VL - A 908 SP - 1 EP - 9 PB - Elsevier B.V. AN - OPUS4-60262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mansurova, Maria A1 - Johann, Sergej A1 - Kohlhoff, Harald A1 - Rurack, Knut A1 - Bartholmai, Matthias A1 - Bell, Jérémy T1 - On-Site Analytical Tool Based on Crude Oil Fluorescence and Chemometrics for the Rapid Determination of the Nature and Essential Properties of Oil Spills N2 - With the reduction of large oil spills because of stricter regulations and safety measures, the question of how to manage smaller oil spills arises. Few on-site analytical tools are available for first responders or other law enforcement personnel to rapidly test for crude oil in the early management of localized polluted areas. The approach reported here relies on well-described computer-assisted multivariate data analysis of the intrinsic fluorescence fingerprints of crude oils to build a multivariate model for the rapid classification of crude oils and the prediction of their properties. Thanks to a dedicated robust portable reader, the method allowed classification and accurate prediction of various properties of crude oil samples like density (according to API, the American Petroleum Institute and viscosity as well as composition parameters such as volume fractions of paraffins or aromatics. In this way, autonomous operation in on-site or in-the-field applications becomes possible based on the direct (undiluted and untreated) measurement of samples and a rapid, tablet-operated readout system to yield a robust and simple analytical test with superior performance. Testing in real-life scenarios allowed the successful classification and prediction of a number of oil spill samples as well as weathered samples that closely resemble samples collected by first responders. KW - Oil spills KW - Fluorescence KW - PCA KW - Petroleum KW - Rapid test KW - Portable PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-595442 DO - https://doi.org/10.1021/acsestwater.3c00648 VL - 4 IS - 2 SP - 621 EP - 627 PB - American Chemical Society (ACS) AN - OPUS4-59544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tukhmetova, Dariya A1 - Lisec, Jan A1 - Vogl, Jochen A1 - Meermann, Björn T1 - Development of an Online Isotope Dilution CE/ICP–MS Method for the Quantification of Sulfur in Biological Compounds N2 - We report an analytical methodology for the quantification of sulfur in biological molecules via a speciesunspecific postcolumn isotope dilution (online ID) approach using capillary electrophoresis (CE) coupled online with inductively coupled plasma−mass spectrometry (online ID CE/ICP−MS). The method was optimized using a mixture of standard compounds including sulfate, methionine, cysteine, cystine, and albumin, yielding compound recoveries between 98 and 105%. The quantity of sulfur is further converted to the quantity of the compounds owing to the prior knowledge of the sulfur content in the molecules. The limit of detection and limit of quantification of sulfur in the compounds were 1.3−2.6 and 4.1−8.4 mg L−1, respectively, with a correlation coefficient of 0.99 within the concentration range of sulfur of 5−100 mg L−1. The capability of the method was extended to quantify albumin in its native matrix (i.e., in serum) using experimentally prepared serum spiked with a pure albumin standard for validation. The relative expanded uncertainty of the method for the quantification of albumin was 6.7% (k = 2). Finally, we tested the applicability of the method on real samples by the analysis of albumin in bovine and human sera. For automated data assessment, a software application (IsoCor) which was developed by us in a previous work was developed further for handling of online ID data. The method has several improvements compared to previously published setups: (i) reduced adsorption of proteins onto the capillary wall owing to a special capillary-coating procedure, (ii) baseline separation of the compounds in less than 30 min via CE, (iii) quantification of several sulfur species within one run by means of the online setup, (iv) SI traceability of the quantification results through online ID, and (v) facilitated data processing of the transient signals using the IsoCor application. Our method can be used as an accurate approach for quantification of proteins and other biological molecules via sulfur analysis in complex matrices for various fields, such as environmental, biological, and pharmaceutical studies as well as clinical diagnosis. Sulfur is an essential element in living organisms, where it plays important roles in various biological processes, such as protein synthesis, enzyme activity, and antioxidant defense. However, the biological effects of different sulfur species can vary widely, and imbalances in sulfur speciation have been observed in a range of diseases, including cancer, Alzheimer’s disease, and diabetes.1−3 The accurate quantification of sulfur and its species in biological samples requires sensitive and selective analytical techniques. In recent years, separation techniques coupled online with inductively coupled plasma−mass spectrometry (ICP−MS) have emerged as powerful online analytical tools complementary to molecular spectrometric methods for speciation analysis of biological compounds. External calibration4−9 and isotope dilution (ID)10−15 are common calibration approaches applied for online quantification of sulfur species in complex samples. The ID analysis is advantageous over. KW - Analytical Chemistry KW - CE/MC-ICP-MS KW - species-specific isotope information PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594736 DO - https://doi.org/10.1021/acs.analchem.3c03553 SN - 0003-2700 SP - 1 EP - 8 PB - American Chemical Society (ACS) AN - OPUS4-59473 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kingsbery, P. A1 - Manzoni, Anna Maria A1 - Suárez Ocano, Patricia A1 - Többens, D. M. A1 - Stephan-Scherb, C. T1 - High‐temperature KCl‐induced corrosion of high Cr and Ni alloys investigated by in‐situ diffraction N2 - High‐temperature KCl‐induced corrosion in laboratory air was observed in situ utilizing X‐ray diffraction. High Cr‐containing model alloys (Fe‐13Cr, Fe‐18Cr‐12Ni, and Fe‐25Cr‐20Ni) were coated with KCl and exposed to dry air at 560°C. KCl‐free alloys were studied in the equivalent atmosphere as a reference. After exposure to KCl‐free environments, all alloys showed the formation of very thin oxide layers, indicating good corrosion resistance. In contrast, KCl‐bearing alloys showed distinct damage after exposure. KW - Corrosion KW - In-situ diffraction KW - High-temperature corrosion PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600831 DO - https://doi.org/10.1002/maco.202314224 SN - 0947-5117 SP - 1 EP - 10 PB - Wiley VHC-Verlag AN - OPUS4-60083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Feng, Wen A1 - Gemming, Thomas A1 - Giebeler, Lars A1 - Qu, Jiang A1 - Weinel, Kristina A1 - Agudo Jácome, Leonardo A1 - Büchner, Bernd A1 - González-Martínez, Ignacio T1 - Influence of magnetic field on electron beam-induced Coulomb explosion of gold microparticles in transmission electron microscopy N2 - In this work we instigated the fragmentation of Au microparticles supported on a thin amorphous carbon film by irradiating them with a gradually convergent electron beam inside the Transmission Electron Microscope. This phenomenon has been generically labeled as “electron beam-induced fragmentation” or EBIF and its physical origin remains contested. On the one hand, EBIF has been primarily characterized as a consequence of beam-induced heating. On the other, EBIF has been attributed to beam-induced charging eventually leading to Coulomb explosion. To test the feasibility of the charging framework for EBIF, we instigated the fragmentation of Au particles under two different experimental conditions. First, with the magnetic objective lens of the microscope operating at full capacity, i.e. background magnetic field B = 2 T, and with the magnetic objective lens switched off (Lorenz mode), i.e. B = 0 T. We observe that the presence or absence of the magnetic field noticeably affects the critical current density at which EBIF occurs. This strongly suggests that magnetic field effects play a crucial role in instigating EBIF on the microparticles. The dependence of the value of the critical current density on the absence or presence of an ambient magnetic field cannot be accounted for by the beam-induced heating model. Consequently, this work presents robust experimental evidence suggesting that Coulomb explosion driven by electrostatic charging is the root cause of EBIF. KW - Electron beam-induced fragmentation KW - Coulomb explosion KW - X-ray diffraction KW - Lorenz transmission electron microscopy PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-600247 DO - https://doi.org/10.1016/j.ultramic.2024.113978 SN - 1879-2723 VL - 262 SP - 1 EP - 8 PB - Elsevier CY - Amsterdam AN - OPUS4-60024 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Merz, Benjamin A1 - Schmidt, Jonathan A1 - Poka, Konstantin A1 - Mohr, Gunther A1 - Polte, Julian A1 - Hilgenberg, Kai T1 - Impact of illumination technique on the detectability of irregularities in high-resolution images of visual in-situ process monitoring in Laser Powder Bed Fusion N2 - The layerwise geometry build-up of additive manufacturing (AM) enables the possibility of in-situ process monitoring. The objective is the detection of irregularities during the build cycle, ensuring component quality and process stability. Focus of this work is the visual in-situ monitoring of the process of powder bed fusion with laser beam of metals (PBF-LB/M). Current state of the art visual monitoring systems for PBF-LB/M are limited by low resolution, allowing the detection of gross flaws. In this work a 65 Mpixel high-resolution monochrome camera is integrated into a commercial PBF-LB/M machine enabling a spatial resolution of approx. 17.2 µm/Pixel. The observed inhomogeneities are clustered into directly detectable irregularities, and indirectly detectable irregularities that can be inferred from the surface. In parallel, two different illumination techniques are realized in the process chamber and compared. The impact of the distinct illumination technique, direct light and dark field, on the identification of irregularities is evaluated. KW - Powder bed fusion with laser beam of metals KW - In-situ monitoring KW - High-resolution camera KW - Illumination technique PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610929 DO - https://doi.org/10.1016/j.procir.2024.08.079 SN - 2212-8271 VL - 124 SP - 98 EP - 103 PB - Elsevier B.V. AN - OPUS4-61092 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Béalu, Zoé A1 - Walther, Johanna A1 - Abusafia, Attaallah A1 - Altmann, Korinna A1 - Meurer, Maren A1 - Gretzschel, Oliver A1 - Schäfer, Michael A1 - Steinmetz, Heidrun T1 - Removal of Organic Micropollutants and Microplastics via Ozonation Followed by Granular Activated Carbon Filtration N2 - Discharge from Wastewater Treatment Plants (WWTPs) can result in the emission of organic micropollutants (OMPs) and microplastics (MPs) into the aquatic environment. To prevent this harmful release, a pilot plant consisting of an ozonation followed by a granular activated carbon (GAC) filter was operated at a WWTP in Germany, and its side-effects on the concentrations of nitrogen (N) and phosphorous (P) compounds were measured. Over 80% of OMPs and transformation products were removed during the operating time (around 6000 bed volumes) no matter the ozone dose (from around 0.1 to 0.5 mgO3/mgDOC), except for Diatrizoic acid, whose breakthrough appeared at 3500 BV. Formation of the oxidation by-product, NDMA, increased with higher ozone doses, but the concentration remained below 100 ng/L. Bromate was formed at a higher ozone dose (0.4 mgO3/mgDOC) but at a low concentration—below 10 µg/L. The MP particles detected in the inflow (PE, SBR, PP, and PS) were effectively eliminated to a high degree, with a removal rate of at least 92%. Carbon parameters (COD, DOC, and SAC254) were removed further by the pilot plant, but to different extents. As expected, nitrate was formed during ozonation, while nitrite’s concentration decreased. Further, nitrite decreased and nitrate increased within the GAC filter, while ammonium was eliminated by at least 90%. Total P concentration decreased after the pilot, but the concentration of PO4-P increased. KW - Microplastics KW - TED-GC/MS KW - Granular Activated Carbon Filtration KW - Removal of Organic Micropollutants KW - Wastewater treatment plant PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-615209 DO - https://doi.org/10.3390/environments11110241 VL - 11 IS - 11 SP - 1 EP - 38 PB - MDPI AG AN - OPUS4-61520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scheuschner, Nils A1 - Oster, Simon A1 - Mohr, Gunther A1 - Hilgenberg, Kai T1 - Comparison of NIR and SWIR thermography for defect detection in Laser Powder Bed Fusion N2 - Since laser powder bed fusion (PBF-LB/M) is prone to the formation of defects during the building process, a fundamental requirement for widespread application is to find ways to assure safety and reliability of the additively manufactured parts. A possible solution for this problem lies in the usage of in-situ thermographic monitoring for defect detection. In this contribution we investigate possibilities and limitations of the VIS/NIR wavelength range for defect detection. A VIS/NIR camera can be based on conventional silicon-based sensors which typically have much higher spatial and temporal resolution in the same price range but are more limited in the detectable temperature range than infrared sensors designed for longer wavelengths. To investigate the influence, we compared the thermographic signatures during the creation of artificially provoked defects by local parameter variations in test specimens made of a nickel alloy (UNS N07208) for two different wavelength ranges (~980 nm and ~1600 nm). KW - Laser powder bed fusion KW - PBF-LB/M KW - Thermography KW - Additive manufacturing KW - NDT PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-610380 DO - https://doi.org/10.1016/j.procir.2024.08.122 VL - 124 SP - 301 EP - 304 PB - Elsevier B.V. AN - OPUS4-61038 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chen, Xinyue A1 - Dong, Ximan A1 - Zhang, Chuyan A1 - Zhu, Meng A1 - Ahmed, Essraa A1 - Krishnamurthy, Giridharan A1 - Rouzbahani, Rozita A1 - Pobedinskas, Paulius A1 - Gauquelin, Nicolas A1 - Jannis, Daen A1 - Kaur, Kawaljit A1 - Hafez, Aly Mohamed Elsayed A1 - Thiel, Felix A1 - Bornemann, Rainer A1 - Engelhard, Carsten A1 - Schönherr, Holger A1 - Verbeeck, Johan A1 - Haenen, Ken A1 - Jiang, Xin A1 - Yang, Nianjun T1 - Interlayer Affected Diamond Electrochemistry N2 - Diamond electrochemistry is primarily influenced by quantities of sp3‐carbon, surface terminations, and crystalline structure. In this work, a new dimension is introduced by investigating the effect of using substrate‐interlayers for diamond growth. Boron and nitrogen co‐doped nanocrystalline diamond (BNDD) films are grown on Si substrate without and with Ti and Ta as interlayers, named BNDD/Si, BNDD/Ti/Si, and BNDD/Ta/Ti/Si, respectively. After detailed characterization using microscopies, spectroscopies, electrochemical techniques, and density functional theory simulations, the relationship of composition, interfacial structure, charge transport, and electrochemical properties of the interface between diamond and metal is investigated. The BNDD/Ta/Ti/Si electrodes exhibit faster electron transfer processes than the other two diamond electrodes. The interlayer thus determines the intrinsic activity and reaction kinetics. The reduction in their barrier widths can be attributed to the formation of TaC, which facilitates carrier tunneling, and simultaneously increases the concentration of electrically active defects. As a case study, the BNDD/Ta/Ti/Si electrode is further employed to assemble a redox‐electrolyte‐based supercapacitor device with enhanced performance. In summary, the study not only sheds light on the intricate relationship between interlayer composition, charge transfer, and electrochemical performance but also demonstrates the potential of tailored interlayer design to unlock new capabilities in diamond‐based electrochemical devices. KW - Nanocrystalline diamond KW - Interfaces KW - Electrochemistry KW - TOF-SIMS KW - SEM PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621576 DO - https://doi.org/10.1002/smtd.202301774 SN - 2366-9608 VL - 9 IS - 2 SP - 1 EP - 10 PB - Wiley VHC-Verlag CY - Weinheim AN - OPUS4-62157 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, Tina A1 - Stark, T. A1 - Arduini, M. A1 - Manara, J. A1 - Altenburg, Simon T1 - Knowing the spectral directional emissivity of 316L and AlSi10Mg PBF-LB/M surfaces: Gamechanger for quantitative in situ monitoring N2 - For a deep process understanding of the laser powder bed fusion process (PBF-LB/M), recording of the occurring surface temperatures is of utmost interest and would help to pave the way for reliable process monitoring and quality assurance. A notable number of approaches for in-process monitoring of the PBF-LB/M process focus on the monitoring of thermal process signatures. However, due to the elaborate calibration effort and the lack of knowledge about the occurring spectral directional emissivity, only a few approaches attempt to measure real temperatures. In this study, to gain initial insights into occurring in the PBF-LB/M process, measurements on PBF-LB/M specimens and metal powder specimens were performed for higher temperatures up to T = 1290 °C by means of the emissivity measurement apparatus (EMMA) of the Center for Applied Energy Research (CAE, Wuerzburg, Germany). Also, measurements at ambient temperatures were performed with a suitable measurement setup. Two different materials—stainless steel 316L and aluminum AlSi10Mg—were examined. The investigated wavelength λ ranges from the visible range (λ-VIS= 0.40–0.75 µm) up to the infrared, λ = 20 µm. The influence of the following factors were investigated: azimuth angle φ, specimen temperature TS, surface texture as for PBF-LB/M surfaces with different scan angles α, and powder surfaces with different layer thicknesses t. T2 - Rapid.Tech 3D 2024 CY - Erfurt, Germany DA - 14.05.2024 KW - PBF-LB/M KW - In situ monitoring KW - Emissivity KW - Additive manufacturing PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-601471 DO - https://doi.org/10.1007/s40964-024-00665-2 SN - 2363-9520 SP - 1 EP - 10 PB - Springer CY - Cham, Switzerland AN - OPUS4-60147 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bühling, Benjamin A1 - Maack, Stefan T1 - Improving onset picking in ultrasonic testing by using a spectral entropy criterion N2 - In ultrasonic testing, material and structural properties of a specimen can be derived from the time-of-flight (ToF). Using signal features, such as the first peak or envelope maximum, to calculate the ToF is error-prone in multipath arrangements or dispersive and attenuating materials, which is not the case for the signal onset. Borrowing from seismology, researchers used the Akaike information criterion (AIC) picker to automatically determine onset times. The most commonly used formulation, Maeda's AIC picker, is reassessed and found to be based on inappropriate assumptions for signals often used in ultrasonic testing and dependent on arbitrary parameters. Consequently, an onset picker for ultrasonic through-transmission measurements is proposed, based on a spectral entropy criterion (SEC) to model the signal using the AIC framework. This SEC picker takes into account the spectral properties of the ultrasonic signal and is virtually free of arbitrary parameters. Synthetic and experimental data are used to compare the performance of SEC and AIC pickers. It is shown that the accuracy of onset picking is improved for densely sampled data. KW - Akaike information criterion picker KW - Nondestructive testing KW - Ultrasound KW - Time of flight PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-594284 UR - https://pubs.aip.org/asa/jasa/article/155/1/544/3061576/Improving-onset-picking-in-ultrasonic-testing-by DO - https://doi.org/10.1121/10.0024337 SN - 0001-4966 VL - 155 IS - 1 SP - 544 EP - 554 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-59428 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kästle, Emanuel D. A1 - Ghaznavi, Ali A1 - Duffner, Eric T1 - Failure monitoring and classification from acoustic emission tests on impact-damaged hydrogen composite pressure vessels N2 - A total of nine heavily damaged carbon-fibre overwrapped pressure vessels are tested. The burst pressure of the damaged vessels correlates with the impact energy and the internal pressure during impact. No internal pressure leads to larger deformation and lower burst pressure. The vessels are tested with acoustic emissions prior to bursting. It can be shown that major instabilities give rise to a significantly increased number of acoustic signals. The location of occurrence corresponds to the impact regions. The signals are studied in terms of their frequency content and it can be shown that high frequency signals experience strong damping so that there are only few recorded high-frequency events and even fewer that are locatable. The data is further used in a cluster analysis to assign the signals to different failure types. With the given experimental design, no clear patterns emerge so that the failure association remains ambiguous. KW - Acoustic Emission KW - Carbon-Fibre Overwrapped Pressure Vessels KW - Impact Damage KW - Cluster Analysis KW - Frequency Features PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613266 DO - https://doi.org/10.58286/30256 SN - 1435-4934 VL - 29 IS - 10 SP - 1 EP - 12 PB - NDT.net GmbH & Co. KG AN - OPUS4-61326 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chan, George C.-Y. A1 - Hieftje, Gary M. A1 - Omenetto, Nicoló A1 - Axner, Ove A1 - Bengtson, Arne A1 - Bings, Nicolas H. A1 - Blades, Michael W. A1 - Bogaerts, Annemie A1 - Bolshov, Mikhail A. A1 - Broekaert, José A.C. A1 - Chan, WingTat A1 - Costa-Fernández, José M. A1 - Crouch, Stanley R. A1 - De Giacomo, Alessandro A1 - D’Ulivo, Alessandro A1 - Engelhard, Carsten A1 - Falk, Heinz A1 - Farnsworth, Paul B. A1 - Florek, Stefan A1 - Gamez, Gerardo A1 - Gornushkin, Igor B. A1 - Günther, Detlef A1 - Hahn, David W. A1 - Hang, Wei A1 - Hoffmann, Volker A1 - Jakubowski, Norbert A1 - Karanassios, Vassili A1 - Koppenaal, David W. A1 - Kenneth Marcus, R. A1 - Noll, Reinhard A1 - Olesik, John W. A1 - Palleschi, Vincenzo A1 - Panne, Ulrich A1 - Pisonero, Jorge A1 - Ray, Steven J. A1 - Resano, Martín A1 - Russo, Richard E. A1 - Scheeline, Alexander A1 - Smith, Benjamin W. A1 - Sturgeon, Ralph E. A1 - Todolí, José-Luis A1 - Tognoni, Elisabetta A1 - Vanhaecke, Frank A1 - Webb, Michael R. A1 - Winefordner, James D. A1 - Yang, Lu A1 - Yu, Jin A1 - Zhang, Zhanxia T1 - Landmark Publications in Analytical Atomic Spectrometry: Fundamentals and Instrumentation Development N2 - The almost-two-centuries history of spectrochemical analysis has generated a body of literature so vast that it has become nearly intractable for experts, much less for those wishing to enter the field. Authoritative, focused reviews help to address this problem but become so granular that the overall directions of the field are lost. This broader perspective can be provided partially by general overviews but then the thinking, experimental details, theoretical underpinnings and instrumental innovations of the original work must be sacrificed. In the present compilation, this dilemma is overcome by assembling the most impactful publications in the area of analytical atomic spectrometry. Each entry was proposed by at least one current expert in the field and supported by a narrative that justifies its inclusion. The entries were then assembled into a coherent sequence and returned to contributors for a round-robin review. KW - Analytical atomic spectrometry KW - Spectroscopy KW - Instrumental analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-621588 DO - https://doi.org/10.1177/00037028241263567 SN - 1943-3530 VL - 78 SP - 1 EP - 456 PB - Sage CY - London AN - OPUS4-62158 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Plouffe, A. A1 - Lee, R. G. A1 - Byrne, K. A1 - Kjarsgaard, I. M. A1 - Petts, D. C. A1 - Wilton, D.H.C. A1 - Ferbey, T. A1 - Oelze, Marcus T1 - Tracing Detrital Epidote Derived from Alteration Halos to Porphyry Cu Deposits in Glaciated Terrains: The Search for Covered Mineralization N2 - Distal alteration related to porphyry Cu mineralization is typically characterized by an abundance of green minerals, such as epidote, tremolite, and chlorite, within the propylitic and sodic-calcic alteration zones and extends far outside (>1 km) the mineralized zone(s). Glacial erosion and dispersal derived from rocks affected by propylitic and sodic-calcic alteration have resulted in the development of extensive dispersal trains of epidote in till (glacial sediment) that can reach 8 to 330 km2 as observed at four porphyry Cu study sites in the Quesnel terrane of south-central British Columbia: Highland Valley Copper, Gibraltar, Mount Polley, and Woodjam deposits. At each of these sites, epidote is more abundant in heavy mineral concentrates of till collected directly over and down-ice from mineralization and associated alteration. Epidote grains in till with >0.6 ppm Sb and >8 ppm As (as determined by laser ablation-inductively coupled plasma-mass spectrometry) are attributed to a porphyry alteration provenance. There is a greater abundance of epidote grains with high concentrations of trace elements (>12 ppm Cu, >2,700 ppm Mn, >7 ppm Zn, and >37 ppm Pb) in each porphyry district com� pared to background regions. This trace element signature recorded in till epidote grains is heterogeneously distributed in these districts and is interpreted to reflect varying degrees of metal enrichment from a porphyry fluid source. Tracing the source of the epidote in the till (i.e., geochemically tying it to porphyry-related propy� litic and/or sodic-calcic alteration), coupled with porphyry vectoring tools in bedrock, will aid in the detection of concealed porphyry Cu mineralization in glaciated terrains. KW - Indicator minerals KW - Porphyry Cu deposits KW - Epidote KW - Glaciated terrains KW - Propylitic alteration PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-635209 DO - https://doi.org/10.5382/econgeo.5049 SN - 1554-0774 VL - 119 IS - 2 SP - 305 EP - 329 PB - Society of Economic Geologists, Inc. AN - OPUS4-63520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Preuß, Bianca A1 - Lindner, Thomas A1 - Hanisch, Niclas A1 - Giese, Marcel A1 - Schröpfer, Dirk A1 - Richter, Tim A1 - Rhode, Michael A1 - Lampke, Thomas T1 - Surface Functionalization of Novel Work‐Hardening Multi‐Principal‐Element Alloys by Ultrasonic Assisted Milling N2 - The development of multi‐principal‐element alloys (MPEAs) with unique characteristics such as high work hardening capacity similar to well‐known alloy systems like Hadfield steel X120Mn12 (ASTM A128) is a promising approach. Hence, by exploiting the core effects of MPEAs, the application range of conventional alloy systems can be extended. In the present study, work‐hardening MPEAs based on the equimolar composition CoFeNi are developed. Mn and C are alloyed in the same ratio as for X120Mn12. The production route consists of cast manufacturing by an electric arc furnace and surface functionalization via mechanical finishing using ultrasonic‐assisted milling (USAM) to initiate work hardening. The microstructure evolution, the hardness as well as the resulting oscillating wear resistance are detected. A pronounced lattice strain and grain refinement due to the plastic deformation during the USAM is recorded for the MPEA CoFeNi‐Mn12C1.2. Consequently, hardness increases by ≈380 HV0.025 in combination with a higher oscillating wear resistance compared to the X120Mn12. This shows the promising approach for developing work‐hardening alloys based on novel alloy concepts such as MPEAs. KW - Electric arc furnace KW - Finish milling KW - High manganese steels KW - Multi-principal element alloy KW - Ultrasonic-assisted milling KW - Work hardening PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-608008 DO - https://doi.org/10.1002/adem.202400339 SN - 1438-1656 SP - 1 EP - 12 PB - Wiley VHC-Verlag AN - OPUS4-60800 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heyn, A. A1 - Meist, M. A1 - Michael, O. A1 - Babutzka, M. A1 - Valet, Svenja A1 - Ebell, Gino T1 - Electrochemical characterization of surfaces of galvanized steels under different exposure conditions using gel electrolytes N2 - The corrosion behavior of galvanized steels and zinc components under atmospheric exposure depends mostly on the corrosion product‐based cover layer formation under the prevailing conditions. The use of agar‐based gel electrolytes makes it possible to use electrochemical methods to obtain a characteristic value from these cover layers that describe their current and future protective capacity. It is shown here that different states of galvanized steel can be distinguished very well under laboratory conditions and that this method is also suitable for use under practical conditions. Based on the characteristic values and assuming future time of wetness, it is very easy to draw up a forecast for the future corrosion rate, which provides plausible values. KW - Materials Chemistry KW - Metals and Alloys KW - Surfaces, Coatings and Films KW - Mechanical Engineering KW - Mechanics of Materials KW - Environmental Chemistry KW - Corrosion KW - Znc PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-599234 DO - https://doi.org/10.1002/maco.202414389 SP - 1 EP - 16 PB - Wiley VHC-Verlag AN - OPUS4-59923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rhode, Michael A1 - Nietzke, Jonathan A1 - Mente, Tobias T1 - Trapping and diffusion in high-pressure hydrogen charged CoCrFeMnNi high entropy alloy compared to austenitic steel 316L N2 - High entropy alloys (HEAs) have attracted considerable research attention as potential substitute materials for austenitic steels in high-pressure hydrogen environments. The corresponding hydrogen absorption, diffusion and trapping has received less scientific attention. Therefore, the CoCrFeMnNi-HEA was investigated and compared to an austenitic steel AISI 316L. Both were subjected to high-pressure hydrogen charging at 200 bar and 1000 bar. Thermal Desorption Analysis (TDA) was used to clarify the specific desorption behavior and hydrogen trapping. For this purpose, the underlying TDA spectra were analyzed in terms of a reasonable peak deconvolution into a defined number of peaks and the activation energies for the respective and predominant hydrogen trapping sites were then calculated. Both materials show comparable hydrogen diffusivity. However, there were significant differences in the absorbed hydrogen concentrations at both charging pressures. The calculated activation energies suggest strong hydrogen trapping in the CoCrFeMnNi-HEA. KW - High-entropy alloy KW - Hydrogen diffusion KW - Trapping KW - High-pressure charging KW - Thermal desorption analysis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-611901 DO - https://doi.org/10.1016/j.ijhydene.2024.09.393 SN - 0360-3199 VL - 89 IS - 89 SP - 772 EP - 782 PB - Elsevier B.V. CY - Amsterdam, Netherlands AN - OPUS4-61190 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Foroutan, Farzad A1 - Abrahams, Isaac A1 - Smales, Glen Jacob A1 - Kanwal, Nasima A1 - di Pasquale, Roberto A1 - Knowles, Jonathan C. A1 - Smith, Andrew J. A1 - Carta, Daniela T1 - A sol-gel templating route for the synthesis of hierarchical porous calcium phosphate glasses containing zinc N2 - Hierarchical porous phosphate-based glasses (PPG) have great potential in biomedicine. Micropores (pore size <2 nm) increase the surface area, mesopores (pore size 2–50 nm) facilitate the absorption and diffusion of therapeutic ions and molecules making them ideal controlled delivery systems, while macropores (pore size >50 nm) facilitate the movement and diffusion of cells and fluids. In addition, the bioresorbability of PPG allows for their complete solubility in body fluid, alongside simultaneous formation of new tissue. Making PPG via the traditional melt-quenching (MQ) synthesis method used for phosphate-based glasses (PG), is not straightforward. Hence, we present here a route for preparing such glasses using a combination of sol-gel (SG) and templating methods. Hierarchical PPG in the P₂O₅–CaO–Na₂O system with the addition of 1, 3 and 5 mol % of Zn²⁺ were prepared with pore dimensions ranging from the micro-to the macro scales using Pluronic 123 (P123) as a surfactant. The presence of micropores (0.30–0.46 nm), mesopores (1.75–9.35 nm) and macropores (163–207 nm) was assessed via synchrotron-based Small-Angle X-ray Scattering (SAXS), with the presence of the latter two confirmed by Scanning Electron Microscopy (SEM). Structural characterisation performed using ³¹P solid state magic angle spinning nuclear magnetic resonance (MAS NMR) and Fourier Transform Infrared (FTIR) spectroscopies shows the presence of Q², Q¹ and Q⁰ phosphate species with a predominance of Q¹ species in all compositions. Dissolution studies in deionised (DI) water confirm that controlled release of phosphates, Ca²⁺, Na⁺ and Zn²⁺ is achieved over a period of 7 days. In particular, the release of Zn²⁺ is proportional to its loading, making its delivery particularly easy to control. KW - Sol-gel KW - Phosphate-based glasses KW - Mesoporous materials KW - Hierarchical porosity PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-613698 DO - https://doi.org/10.1016/j.ceramint.2024.07.180 SN - 0272-8842 VL - 50 IS - 20, Part A SP - 38174 EP - 38182 PB - Elsevier CY - Amsterdam AN - OPUS4-61369 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hayward, E. C. A1 - Smales, Glen Jacob A1 - Pauw, Brian Richard A1 - Takeguchi, M. A1 - Kulak, A. A1 - Hunter, R. D. A1 - Schnepp, Z. T1 - The effect of catalyst precursors on the mechanism of iron-catalysed graphitization of cellulose N2 - Iron-catalysed graphitization of biomass is a simple and sustainable route to carbons with high graphitic content. It uses abundant precursors and moderate processing temperatures and generates carbons with high porosity. Recently, it has been demonstrated that the choice of biomass precursor can have a significant impact on the textural and compositional properties of the resulting carbon. In this paper, we demonstrate that the choice of catalyst is also critical to the carbon structure. Aqueous iron(III) nitrate and iron(III) chloride convert cellulose to carbons with very different textural properties. This is due to the choice of iron catalyst changing the mechanism of cellulose decomposition and also the nature of the active graphitization catalyst. KW - Catalyst KW - Carbon materials KW - Cellulose KW - Small-angle scattering KW - Green energy KW - Graphitic carbon KW - Green synthesis PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-614800 DO - https://doi.org/10.1039/D4SU00365A SP - 1 EP - 10 PB - Royal Society of Chemistry (RSC) AN - OPUS4-61480 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tamburini, Federica A1 - Kluge, Martin A1 - Habib, Abdel Karim A1 - Ustolin, Federico A1 - Cozzani, Valerio A1 - Paltrinieri, Nicola T1 - Exploring experimental tests concerning liquid hydrogen releases N2 - In recent years, the adoption of liquid hydrogen (LH2) has increased significantly in industrial and transport applications, driven by its low carbon footprint, thereby aiding the fight against global warming. Additionally, its high volumetric energy density, compared to gaseous or compressed hydrogen, enhances hydrogen storage capabilities. However, safety remains a major concern due to its physical-chemical properties and inherent hazardous characteristics, especially in the event of spillage scenarios. Therefore, to better understand the consequences of LH2 releases onto or into water, large-scale experimental tests were conducted by Bundesanstalt für Materialforschung und -prüfung (BAM) within the Safe Hydrogen Fuel Handling and Use for Efficient Implementation (SH2IFT) project at the Test Site Technical Safety of BAM, comprising 75 single spill events at varied release rates and orientations. While the rapid phase transition (RPT) phenomenon was not observed, selfignition of the hydrogen-air cloud occurred, accompanied by blast wave overpressure and heat radiation, without a discernible ignition source. These findings emphasize the need for further investigation into LH2 safety. Leveraging experimental data for real-world applications provides insights into safe LH2 infrastructure implementation, laying foundational knowledge for addressing safety challenges and advancing LH2 technology. KW - Liquid Hydrogen KW - Rapid phase transition KW - Ignition KW - Safety PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-618644 DO - https://doi.org/10.1016/j.psep.2024.11.014 SN - 0957-5820 VL - 192 SP - 1330 EP - 1343 PB - Elsevier CY - Amsterdam AN - OPUS4-61864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gordon, Nehemia A1 - Patrick, Andrist A1 - Hahn, Oliver A1 - Vasileiadis, Pavlos D. A1 - Calvillo, Nelson A1 - Rabin, Ira T1 - Did the Original Scribes Write the Distigmai in Codex Vaticanus B of the Bible (Vat. gr. 1209)? N2 - The fourth-century Greek Bible manuscript Codex Vaticanus B (Vat. gr. 1209) contains pairs of horizontally aligned marginal dots known as distigmai, which correspond to textual variants in other manuscripts. The production of the distigmai has been variously dated to the 4th or 16th centuries. A fourth-century date would prove the early existence of hundreds of textual variants, many of which are otherwise only witnessed by later manuscripts. Near infrared microscope reflectography combined with micro-X-ray fluorescence spectroscopy proved that the distigmai, both those categorized as “apricot” (which are visually similar to the ink of the original main text) and “chocolate” (which are visually similar to the reinking of the main text) were written with ink(s) made from chemically purified vitriol, a process that only became standard in the 16th century. As a result, there is no reasonable chance that the distigmai were written in the fourth century. Horizontal lines that have been hypothesized to function as text-critical obeloi were written in the same ink as the original main text, which differs completely from that of the distigmai. In other words, the distigmai and horizontal lines tested were not produced during the same writing session and are separated by more than 1,000 years, making it impossible for them to have functioned as conjoining text-critical symbols in the 4th century. KW - Bible manuscripts KW - New Testament KW - Paratextual features KW - Textual criticism KW - Obelos KW - Septuagint KW - XRF KW - Greek palaeography PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-622902 DO - https://doi.org/10.1163/27728641-00302005 SN - 2772-8633 VL - 3 IS - 2 SP - 125 EP - 156 PB - Brill CY - Leiden AN - OPUS4-62290 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Blaeß, Carsten A1 - Müller, Ralf T1 - Viscous crack healing in soda–lime–magnesium–silicate–ZrO2 glass matrix composites N2 - AbstractThe present study investigates the influence of the crystal volume content on viscous crack healing in glass ceramic glass sealants. To ensure constant microstructure during healing, soda–lime–magnesium silicate glass matrix composites with varied volume fractions of ZrO2 filler particles were used. Crack healing was studied on radial cracks induced by Vickers indentation, which were stepwise annealed to monitor the healing progress by confocal laser scanning microscopy. Confirming previous studies, healing of radial cracks in pure glass was found delayed by global flow phenomena like crack widening and crack edge and tip rounding to minimize the sample surface. With increasing ZrO2 filler content, these global flow phenomena were progressively inhibited whereas local flow phenomena like sharp crack tip healing could still occur. As a result, crack healing was even accelerated by filler particles up to a maximum filler content of 17 vol% whereas crack healing was fully suppressed only at 33 vol% filler content. KW - Crack healing KW - Glass matrix composite KW - Solid oxide fuell cell KW - Vickers identation KW - Viscosity PY - 2024 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-607860 DO - https://doi.org/10.1111/jace.20002 SN - 0002-7820 SP - 1 EP - 12 PB - Wiley AN - OPUS4-60786 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -