TY - CONF A1 - Reinsch, Stefan A1 - Waurischk, Tina A1 - Müller, Ralf A1 - Arendt, F. A1 - Sierka, M. A1 - Diegeler, A. T1 - A new robot-assisted compositional screening method N2 - The system Na2O.B2O3-SiO2 (NBS) is the basis of many industrial glass applications and therefore one of the most studied systems at all. Glass formation is possible over a wide compositional range, but the system also contains ranges of pronounced phase separation and crystallization tendency. Despite its importance, experimental data are limited to few compositional areas. The general understanding and modelling of glass formation, phase separation, and crystallization in this system would therefore be easier if small step melt series could be studied. The efficient melting of such glass series is now possible with the new robotic glass melting system at the Federal Institute for Materials Research and Testing (BAM, Division Glasses). Using three exemplary joins within this NBS system, the small step changes of glass transition temperature (Tg), crystallization behavior as well as glass density (Roh) was studied. Additionally, experimental Tg and Roh data were compared with their modeled counterparts using SciGlass and a newly developed DFT model, respectively. T2 - Annual meeting of the French Union for Science and Glass Technology (USTV) and the 96th Annual Meeting of the German Society of Glass Technology - USTV-DGG joint meeting. CY - Orléans, France DA - 22.06.2023 KW - Robot-assisted galss melting KW - Sodiumborosilicate glasses KW - Density KW - Glass transformation temperature KW - Property simulation PY - 2023 AN - OPUS4-58724 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan A1 - Lindemann, Franziska A1 - Wohlleben, W. T1 - Advanced screening method using volume-specific surface area (VSSA) for nanomaterial identification of powders N2 - The EC’s recommendation for a definition of nanomaterial (2011/696/EU) should allow the identification of a particulate nanomaterial based on the number-based metric criterion according to which at least 50% of the constituent particles have the smallest dimension between 1 and 100 nm. However, it has been recently demonstrated that the implementation of this definition for regulatory purposes is conditioned by the large deviations between the results obtained by different sizing methods or due to practical reasons such as high costs and time-consuming (SEM, TEM). Within the European project NanoDefine (www.nanodefine.eu) a two-tier approach has been developed, whereby firstly a screening method is applied for the rough classification as a nano-/non-nanomaterial, and for borderline cases a confirmatory method (imaging methods or field flow fractionation) must be considered. One of the measurement methods well suited to particulate powder is the determination of volume-specific surface area (VSSA) by means of gas adsorption as well as skeletal density. The value of 60 m2/cm3 corresponding to spherical, monodisperse particles with a diameter of 100 nm constitutes the threshold for decisioning if the material is a nano- or non-nanomaterial. The correct identification of a nanomaterial by VSSA method is accepted by the EU recommendation. However, the application of the VSSA method is associated also by some limitations. The threshold of 60 m2/cm3 is dependent on the particle shape, so that it changes considerably with the number of nano-dimensions of the particles. For particles containing micro-pores or having a microporous coating false positive results will be produced. Furthermore, broad particle size distributions make necessary to adjust the threshold. Based on examples of commercially available ceramic powders, the applicability of the VSSA approach will be tested (in relation with SEM and TEM measurements) in order to expand the actual knowledge and to improve this good available and agglomeration tolerant method. T2 - Workshop on Reference Nanomaterials CY - Berlin, Germany DA - 14.05.2018 KW - VSSA KW - Nanomaterial screening KW - Nano-powder characterization PY - 2018 AN - OPUS4-45099 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan A1 - Lindemann, Franziska A1 - Gemeinert, Marion A1 - Wohlleben, W. T1 - Advanced screening method using volume-specific surface area (VSSA) for nanomaterial classification of powders N2 - The EU recommendation for a definition of nanomaterial (2011/696/EU) should allow the identification of a particulate nanomaterial based on the number-based metric criterion according to which at least 50% of the constituent particles have the smallest dimension between 1 and 100 nm. Within the European Project NanoDefine (www.nanodefine.eu) a two-tier approach has been developed, whereby firstly a screening method is applied for the rough classification as a nanomaterial or non-nanomaterial, and for borderline cases a confirmatory method (imaging methods or field flow fractionation) must be considered. One of the measurement methods well suited to particulate powder is the determination of volume-specific surface area (VSSA) by means of gas adsorption as well as skeletal density. The value of 60 m2/cm3 corresponding to spherical, monodisperse particles with a diameter of 100 nm constitutes the threshold for decisioning if the material is a nanomaterial or non-nanomaterial. The correct identification of a nanomaterial by VSSA method (positive test) is accepted by the EU recommendation. However, the application of the VSSA method is associated also by some limitations. The threshold of 60 m2/cm3 is dependent on the particle shape. For particles containing micro-pores or having a microporous coating, false positive results will be produced. Furthermore, broad particle size distributions – as typically for ceramic materials – as well as multi-modal size distributions make necessary to adjust the threshold. Based on examples of commercially available ceramic powders, the applicability of the VSSA approach will be tested (in relation with SEM and TEM measurements) in order to expand the actual knowledge and improve the method. T2 - Jahrestagung der Deutschen Keramischen Gesellschaft mit Symposium Hochleistungskeramik CY - München, Germany DA - 10.04.2018 KW - VSSA KW - Nanoparticles PY - 2018 AN - OPUS4-45097 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilling, Markus A1 - Marschall, Niklas A1 - Niebergall, Ute A1 - Böhning, Martin T1 - An optical criterion for the assessment of Full-Notch Creep Test (FNCT) fracture surfaces N2 - The full-notch creep test (FNCT) is a common method to evaluate the environmental stress cracking (ESC) behavior of high-density polyethylene (PE-HD) container materials . The test procedure as specified in ISO 16770 provides a comparative measure of the resistance against ESC using the time to failure of specimens mechanically loaded in a well-defined liquid environment. Since the craze-crack damage mechanism underlying the ESC process is associated with brittle failure, the occurrence of globally brittle fracture surfaces is a prerequisite to consider an FNCT measurement as representative for ESC . Therefore, an optical evaluation of FNCT fracture surfaces concerning their brittleness is essential. Due to the experimental setup, an inevitable increase of the true mechanical stress and the associated appearance of small ductile parts on fracture surfaces is induced in any case. Hence, an FNCT experiment is considered as 'valid', if the corresponding fracture surface is predominantly brittle . Based on laser scanning microscopy (LSM) height data of FNCT fracture surfaces , a universal and easy-to-use phenomenological criterion was developed to assess the validity of distinct FNCT experiments. This criterion is supposed to facilitate a quick evaluation of FNCT results in practical routine testing. T2 - PPS Europe-Africa 2019 Regional Conference (PPS 2019) CY - Pretoria, South Africa DA - 18.11.2019 KW - Full-Notch Creep Test (FNCT) KW - Polyethylene, PE-HD KW - Fracture surface analysis KW - Environmental stress cracking (ESC) KW - Optical criterion KW - Brittle fracture PY - 2019 AN - OPUS4-50940 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heuser, Lina A1 - Schmid, Thomas A1 - Deubener, J. T1 - An overview of structural, physical and thermal properties of low melting zinc and lead borate glasses N2 - Low melting zinc borate glasses awake interest to replace lead borate glasses in the silver metallization pastes for solar cells or microelectronics. In the current study, characteristic properties of alkali zinc borate glasses (X2O-ZnO-B2O3, X = Li, Na, K, Rb) were compared to an earth alkali zinc borate glass (CaO-ZnO-B2O3). Additionally, zinc oxide is partially substituted by lead oxide or cooper oxide in the borate glasses (Li2O-PbO-B2O3, Na2O ZnO CuO-B2O3). The alkali zinc borate glasses indicate less differences in Raman spectra, and thus in structural properties, in comparison to the Ca and Pb ions influence. LPbB (Tg = 401 °C) has a lower viscosity than LZB (Tg = 468 °C) and CaZB has the highest glass transition temperature (Tg = 580 °C). The Angell plot for the alkali zinc borate glasses shows a high fragility m = 80. Besides Tg, the density measured by means of the Archimedean principle, molar volume, and coefficient of thermal expansion (CTE) of the glasses were investigated. Trends could be found according to alkali ions or intermediate oxides. The density increases with decreasing alkali ion size from KZB (2.632 g/cm3) to LZB (2.829 g/cm3) and increases from LZB to LPbB (3.764 g/cm3). CTE ranges between 7.09 10-6 K-1 for CaZB and 11.5 10 6 K 1 for KZB and RZB. The differential thermal analysis (DTA) and X ray diffraction (XRD) indicate crystallization of various crystalline phases during heating with 5 K/min in most cases. T2 - 94. Glastechnische Tagung CY - Online meeting DA - 10.05.2021 KW - Borate glasses KW - Glass structure KW - Viscosity KW - Young´s Modulus KW - Alkali ions PY - 2021 AN - OPUS4-52867 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mueller, Axel A1 - Duemichen, E. A1 - Eisentraut, Paul A1 - Braun, Ulrike A1 - Scholz, K. A1 - Bannick, C.-G. T1 - Analysing microplastics in samples of terrestrial systems N2 - The presence, fate and effects of microplastics (MP) in terrestrial systems are largely unknown. The few existing studies investigated either agricultural or industrial sites. Several techniques were used for analysis, primarly spectroscopic methods such as FTIR or Raman. Sample pretreatments like density separations are common to reduce matrix. A lack of harmonised and standardised sampling instructions for microplastic investigations in the terrestrial area was identified as particular critical, because different studies are barely comparable. The aim of the project is to develop a proposal for a harmonized procedure for sampling, sample preparation and the detection of microplastics in terrestrial matrices for total content determination. By detecting specific degradation products the thermal extraction desorption gas chromatography mass spectrometry (TED-GC-MS) allows a direct determination of mass content of MP in environmental samples. T2 - SETAC 2018 CY - Rome, Italy DA - 13.05.2018 KW - Microplastics KW - Soil sample KW - TED-GC-MS KW - Analysis PY - 2018 AN - OPUS4-44988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Röhsler, Andreas A1 - Sobol, Oded A1 - Nolze, Gert A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang T1 - Analysis of deuterium in austenitic stainless steel AISI 304L by Time-of-Flight Secondary Ion Mass Spectrometry N2 - Due to their excellent combination of ductility, strength and corrosive resistance, austenitic stainless steels (ASS) are widely used in many industrial applications. Thus, these steel grades can be found as structural components in the (petro-)chemical industry, in offshore applications and more recent for storage and transport of hydrogen fuel. Steels employed for these applications are exposed to aggressive environments and hydrogen containing media. The ingress and accumulation of hydrogen into the microstructure is commonly observed during service leading to a phenomenon called “hydrogen embrittlement”. A loss in ductility and strength, the formation of cracks and phase transformations are typical features of this hydrogen-induced degradation of mechanical properties. Although, great efforts are made to understanding hydrogen embrittlement, there is an ongoing debate of the underlying mechanisms. This knowledge is crucial for the safe use and durability of components on the one side and the development of new materials on the other. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was proven to be a powerful tool for depicting the distribution of the hydrogen isotope deuterium in the microstructure of austenitic and duplex steels. The combination with imaging techniques such as electron backscatter diffraction (EBSD) and scanning electron microscopy (SEM), delivering structural and morphological information, creates a comprehensive picture of the hydrogen/deuterium-induced effects in the materials. All the gathered data is treated with principal component analysis (PCA) and data fusion to enhance the depth of information. The mobility of hydrogen and deuterium in a steel microstructure is affected by external mechanical stress. To investigate the behaviour of deuterium in a strained microstructure, a new in situ experimental approach was developed. This gives the possibility of analysing samples in the SIMS instrument simultaneously to four-point-bending-tests. Specimens made from ASS AISI 304L were electrochemically charged with deuterium instead of hydrogen. This necessity stems from the difficulty to separate between artificially charged hydrogen and hydrogen existing in the pristine material or adsorbed from the rest gas in the analysis chamber. Nonetheless, similar diffusion, permeation and solubility data allow to draw qualitative conclusions from the experiments, which are relevant for the application addressed. T2 - SIMS Europe 2018 CY - Münster, Germany DA - 16.09.2018 KW - Hydrogen KW - Deuterium KW - Austenitic stainless steel KW - SIMS PY - 2018 AN - OPUS4-46029 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Ávila, Luis A1 - Rehmer, Birgit A1 - Graf, B. A1 - Ulbricht, Alexander A1 - Skrotzki, Birgit A1 - Rethmeier, Michael T1 - Assessing the low cycle fatigue behaviour of additively manufactured Ti-6Al-4V: Challenges and first results N2 - The understanding of process-microstructure-property-performance (PMPP) relationships in additive manufacturing (AM) of metals is highly necessary to achieve wide-spread industrial application and replace conventionally manufactured parts, especially regarding safety-relevant applications. To achieve this understanding, reliable data and knowledge regarding material’s microstructure-property relationships (e.g. the role of defects) is needed, since it represents the base for future more targeted process optimizations and more reliable calculations of performance. However, producing reliable material data and assessing the AM material behaviour is not an easy task: big challenges are e.g. the actual lack of standard testing methods for AM materials and the occasional difficulties in finding one-to-one comparable material data for the conventional counterpart. This work aims to contribute to end this lack of reliable material data and knowledge for the low cycle fatigue behaviour of the most used titanium alloy in aerospace applications (Ti-6Al-4V). For this purpose, two sets of test specimens were investigated. The first set was manufactured from cylindrical rods produced by an optimized DED-L process and the second was manufactured from a hot formed round bar. The test specimens were cyclically loaded until failure in the low-cycle-fatigue (LCF) regime. The tests were carried out according to ISO 12106 between 0.3 to 1.0 % axial strain amplitude from room temperature up to 400°C. The LCF behaviour is described and compared between materials and with literature values based on cyclic deformation curves and strain-based fatigue life curves. Besides, the parameters of Manson-Coffin-Basquin relationship were calculated. The microstructures (initial and after failure) and fracture surfaces were comparative characterized. Thereby, the focus lied on understanding the role of grain morphology and defects on the failure mechanisms and fatigue lifetimes. For this latter characterization, optical microscopy (OM), scanning electron microscopy (SEM) and micro computed tomography (µCT) were used. T2 - 4th International Symposium on Fatigue Design and Material Defects CY - Online meeting DA - 26.05.2020 KW - Ti-6Al-4V KW - Additive manufacturing KW - Low cycle fatigue KW - Micro computed tomography KW - Microstructure PY - 2020 AN - OPUS4-50893 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - von Hartrott, P. A1 - Rockenhäuser, Christian A1 - Metzger, M. A1 - Skrotzki, Birgit T1 - Assessment of EN AW-2618A for high temperature applications considering aging effects N2 - The alloy EN AW-2618A was assessed regarding its properties for high temperature applications considering aging effects. T2 - BAM TMF-Workshop 2019 CY - Berlin, Germany DA - 13.11.2019 KW - Alloy 2618A KW - Degradation KW - Coarsening KW - Transmission electron microscopy KW - Dark-field transmission electron microscopy (DFTEM) PY - 2019 AN - OPUS4-49808 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Orlov, Nikolai A1 - Milkin, P. A1 - Evdokimov, P A1 - Putlayev, V. A1 - Günster, Jens A1 - Nicolaides, Dagmar T1 - Bioceramics from Ca3(PO4)2 - CaKPO4 - CaNaPO4 system for bone replacement and grafting N2 - Biomaterials for bone replacement and grafting should possess sufficient strength, be bioresorbable and demonstrate osteoconductivity/osteoinductivity. Nowadays, hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most widespread ceramics for bone grafting at the market, however, their resorption is reported, in some cases, to be not enough. This is why the search for more soluble ceramics compared to HA and TCP looks rather viable. A possible way to increase ceramics solubility leads to partial substitution of Ca2+-ions in Ca3(PO4)2 by alkali castions, like Na+ or/and K+. Improvement of solubility stems from decreasing lattice energy of a substituted phase, as well as increase in hydration energy of the ions releasing from the phase to ambient solution. From this viewpoint, bioceramics based on compositions from Ca3(PO4)2 - CaKPO4 - CaNaPO4 ternary system seems to be prospective for bone replacement and grafting in sense of resorption properties. At the same time, one should bear in mind that solubility level (resorbability) is governed not only by reduction of lattice energy, but also by microstructure features. Grain sizes and porosity contribute much to dissolution rate making study of sintering of aforementioned ceramics highly important. T2 - Biomaterials and Novel Technologies for Healthcare, 2nd International Biennial Conference BioMaH CY - Frascati (Rome), Italy DA - 08.10.2018 KW - Bio Ceramics KW - Bioresorbable PY - 2018 AN - OPUS4-46035 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Junge, P. A1 - Greinacher, M. A1 - Kober, D. A1 - Mieller, Björn T1 - Bulk vs thermal sprayed alumina for insulation applications: A comparison of electrical and dielectrical properties N2 - Additive manufacturing (AM) processes are opening new design possibilities for large scale electrical devices such as power generators. Conventional manufacturing methods use copper rods which are wrapped, vacuum impregnated, bend and welded. These processes are labor-intensive and time-consuming. The introduction of AM methods for manufacturing the copper conductor and electrical insulation can reduce the size of the generator head, the most complex part of the generator. In this study, the electrical and dielectrical properties of additively deposited ceramic layers are investigated and compared with the properties of conventionally fabricated bulk ceramics. The ceramic layers are thermally deposited by atmospheric plasma spraying of a commercially available alumina powder. Bulk ceramics are fabricated by dry pressing and sintering of the same powder. Microstructure and porosity were analyzed by scanning electron microscopy (SEM). Electrical and dielectrical properties such as DC resistance, dielectric strength, dielectric loss, and relative permittivity were determined according to the standards. The microstructures of sprayed and sintered alumina show significant differences with respect to grain form and porosity. The density of the bulk ceramic is lower than the density of the sprayed layer due to the coarse particle size (d50 = 33 μm). Therefore, data from dense samples of the same chemical composition but lower particle size alumina powder were used for comparison. T2 - Keramik 2022 CY - Online meeting DA - 07.03.2022 KW - High Voltage Insulation KW - Thermal Spray KW - Dielectric Spectroscopy KW - Atmospheric Plasma Spraying PY - 2022 AN - OPUS4-54446 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Busch, R. A1 - Tielemann, Christopher A1 - Reinsch, Stefan A1 - Patzig, C. A1 - Höche, T. A1 - Müller, Ralf T1 - Characterization of early crystallization stages in surface-crystallized diopside glass-ceramics N2 - Structure formation in glass-ceramics by means of surface crystallization is a challenging open question and remains elusive to definite answers. In several glass-ceramic systems, oriented crystal layers have been observed at the immediate surface, including diopside and some fresnoite systems. However, it is still open to debate, whether oriented surface crystallization is the result of oriented nucleation or growth selection effects. In the same vein, there is still discussion whether surface nucleation is governed by surface chemistry effects or by defects serving as active nucleation sites. In order to help answer these questions, annealing experiments at 850°C have been performed on a MgO·CaO·2SiO2 glass, leading to the crystallization of diopside at the surface. Different annealing durations and surface treatment protocols (i.a. lapping with diamond slurries between 16 µm and 1 µm grain size) have been applied. Particular focus has been put on earliest crystallization stages, with crystal sizes down to about 200 nm. The resultant microstructure has been analyzed by electron backscatter diffraction (EBSD) and two different kinds of textures have been observed, with the a- or b-axis being perpendicular to the sample surface and the c-axis lying in the sample plane. Even at shortest annealing durations, a clear texture was present in the samples. Additionally, selected samples have been investigated with energy-dispersive x-ray spectroscopy in the scanning transmission electron microscope (STEM-EDX). The diopside crystals have been found to exhibit distinguished submicron structure variations and the glass around the crystals was shown to be depleted of Mg. T2 - 93rd Annual Meeting of the German Society of Glass Technology in Conjunction with the Annual Meeting of French Union for Science and Glass Technology (USTV) CY - Nuremberg, Germany DA - 13.05.2019 KW - Glass KW - Crystallization KW - Diopside KW - EBSD KW - Orientation PY - 2019 AN - OPUS4-49296 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Winckelmann, Alexander A1 - Hoffmann, V. A1 - Morcillo, Dalia A1 - Agudo Jacome, Leonardo A1 - Leonhardt, Robert A1 - Richter, Silke A1 - Recknagel, Sebastian A1 - Abad Andrade, Carlos Enrique A1 - You, Zengchao T1 - Chemical characterization of aging processes in high energy-density lithium-ion batteries N2 - Introduction Lithium-ion batteries (LIBs) are one key technology to overcome the climate crisis and energy transition challenges. Demands of electric vehicles on higher capacity and power drives research on innovative cathode and anode materials. These high energy-density LIBs are operated at higher voltages, leading to increased electrolyte decay and the current collectors' degradation. Even though this fundamental corrosion process significantly affects battery performance, insufficient research is being done on the aluminum current collector. Fast and convenient analytical methods are needed for monitoring the aging processes in LIBs. Methods In this work glow-discharge optical emission spectrometry (GD-OES) was used for depth profile analysis of aged cathode material. The measurements were performed in pulsed radio frequency mode. Under soft and controlled plasma conditions, high-resolution local determination (in depth) of the elemental composition is possible. Scanning electron microscopy (SEM) combined with a focused ion beam (FIB) cutting and energy dispersive X-ray spectroscopy (EDX) was used to confirm GD-OES results and obtain additional information on elemental distribution. Results The aging of coin cells manufactured with different cathode materials (LCO, LMO, NMC111, NMC424, NMC532, NMC622, and NMC811) was studied. GD-OES depth profiling of new and aged cathode materials was performed. Quantitative analysis was possible through calibration with synthetic standards and correction by sputter rate. Different amounts of aluminum deposit on the cathode surface were found for different materials. The deposit has its origin in the corrosion of the aluminum current collector. The results are compatible with results from FIB-EDX. However, GD-OES is a faster and less laborious analytical method. Therefore, it will accelerate research on corrosion processes in high energy-density batteries. Innovative aspects - Quantitative depth profiling of cathode material -Monitoring of corrosion processes in high energy-density lithium-ion batteries - Systematic investigation of the influence of different cathode materials T2 - ANAKON 2023 CY - Vienna, Austria DA - 11.04.2023 KW - Lithium Ion Batteries KW - GD-OES KW - Depth-profiling PY - 2023 AN - OPUS4-58586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baesso, Ilaria A1 - Altenburg, Simon A1 - Günster, Jens T1 - Co-axial online monitoring of Laser Beam Melting (LBM) N2 - Within the perspective of increasing reliability of AM processes, real-time monitoring allows part inspection while it is built and simultaneous defect detection. Further developments of real-time monitoring can also bring to self-regulating process controls. Key points to reach such a goal are the extensive research and knowledge of correlations between sensor signals and their causes in the process. T2 - BAM workshop on Additive Manufacturing CY - BAM, Berlin, Germany DA - 13.05.2019 KW - Laser Beam Melting KW - Process Monitoring KW - Co-axial monitoring KW - 3D imaging PY - 2019 AN - OPUS4-48517 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Stargardt, Patrick A1 - Bresch, Sophie A1 - Walter, P A1 - Stargardt, Patrick A1 - Höhne, Patrick A1 - Moos, R A1 - Mieller, Björn T1 - Comparison of design concepts for ceramic oxide thermoelectric multilayer generators N2 - Multilayer thermoelectric generators are a promising perspective to the conventional π-type generators. Ceramic multilayer technology is well established for production of microelectronics and piezo-stacks. Key features of ceramic multilayer technology are full-automation, cost-effectiveness, and the co-firing of all materials in one single step. This requires similar sintering temperatures of all used materials. The development of multilayer thermoelectric generators is a subject of current research due to the advantages of this technology. One of the challenges is the compatibility of the different materials with respect to the specific design. The presented study compares three different designs of multilayer generators based on a given set of material properties. Dualleg, unileg and transverse multilayer generators are compared to conventional π-type generators., the designs are evaluated regarding the expected maximum output power and power density using analytical calculations and FEM simulations. Additionally, the complexity of the production process and material requirements are assessed and design optimizations to simplify production are discussed. Besides the theoretical aspects, unileg multilayer generator prototypes were produced by tape-casting and pressure-assisted sintering. These prototypes are compared to other multilayer generators from literature regarding the power factors of the used material system and the power density. Improvements of the power output by design optimizations are discussed T2 - 18th European Conference on Thermoelectrics CY - Barcelona, Spain DA - 13.09.2022 KW - Thermoelectric oxides KW - Thermoelectric generator design PY - 2022 AN - OPUS4-55820 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Werner, Tiago A1 - Madia, Mauro A1 - Zerbst, Uwe A1 - Sonnenburg, Elke T1 - Comparison of the fatigue behavior of wrought and additively manufactured AISI 316L N2 - Additively Manufactured (AM) parts are still far from being used in safety-relevant applications, mainly due to a lack of understanding of the feedstock-process-propertiesperformance relationship. This work aims at providing a characterization of the fatigue behavior of the additively manufactured AISI 316L austenitic stainless steel and a direct comparison with the fatigue performance of the wrought steel. A set of specimens has been produced by laser powder bed fusion (L-PBF) and a second set of specimens has been machined out of hot-rolled plates. The L-PBF material shows a higher fatigue limit and better finite life performance compared to the wrought material, accompanied by an extensive amount of cyclic softening. T2 - Fatigue Design 2021 CY - Online meeting DA - 17.11.2021 KW - Additive Manufacturing KW - AM KW - 316L KW - Fatigue KW - High Cycle Fatigue KW - Low Cycle Fatigue PY - 2021 AN - OPUS4-53780 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Weinel, Kristina A1 - Hesse, René A1 - Agudo Jacome, Leonardo A1 - Gonzalez-Martinez, I. T1 - Complex artificial features on a TEM transparent membrane N2 - The phenomenon of expelling nanomaterial from microparticles of different materials, such as Au, WO3 or B2O3 under the influence of a convergent electron beam (CB) of a transmission electron microscope (TEM) was reviewed by Ignacio Gonzalez-Martinez [1]. Converging the e-beam in a TEM means that a high amount of energy enters the microparticle at a very local place and interact with the matter. Obviously, during the convergent beam protocol, no imaging with the electron beam is possible, but at the end, nanoparticles with different appearances lie down next to the microparticle while its size is reduced. Hence, there is a blind spot in the observation, which we want to fill, as we want to help clarify the nature of the expelling phenomenon. One hypothesis that explains the phenomenon is the so-called damage (of the microparticle) induced by an electric field (DIEF). Within this theory, the material is ionized and expelled in form of ionic waves. Our aim is therefore to fabricate specimens with artificial microlandscapes, as schematically exemplified in figure 1a), using the focused ion beam (FIB) and micromanipulators, as experimental setups to follow the paths of the expelled material. As a first step towards the fabrication of such specimen, we make experimental feasibility studies for each fabrication method, FIB structuring with Ga+ ion beam and micromanipulated microparticle deposition. Bridges (gray regions in Fig. 1) are created by milling a commercially available electron transparent membrane (silicon oxide or carbon) of a Cu-TEM grid. Platinum or carbon walls (blue features in Fig. 1) are built to stand on those bridges. Microparticles (yellow sphere in Fig. 1) of gold or other material are deposited in the center of the bridges. Figure 2a) shows four square holes (black area) and between them the residual silicon oxide membrane bridges (dark grey). On top of the bridges, walls (light grey) are deposited. The width of the bridges is different, the walls overlap the holes as well as the distance between the walls is very small, so these and other parameters need to be optimized. Figure 2b) shows a square hole (black) with bridges (white) on the right side on top of a carbon membrane (grey). There are still some obstacles which needs to be eliminated. For instance, the deposition process of the walls is not reliable as visible at the wall on top where a hole arises instead of a wall. These studies are still in progress and the results are further discussed in terms of the applicability for the DIEF experiment in the TEM. T2 - 4th EuFN and FIT4NANO Joint Workshop / Meeting CY - Vienna, Austria DA - 27.09.2021 KW - Transmission electron microscope (TEM) KW - Sample preparation KW - Micromanipulation KW - Focussed ion beam growth KW - Nano-landscape PY - 2021 AN - OPUS4-58259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kuchenbecker, Petra A1 - Hodoroaba, Vasile-Dan T1 - Considerations for nanomaterial identification of powders using volume-specific surface area method N2 - The EC’s recommendation for a definition of nanomaterial (2011/696/EU) should allow the identification of a particulate nanomaterial based on the number-based metric criterion according to which at least 50% of the constituent particles have the smallest dimension between 1 and 100 nm. However, it has been recently demonstrated that the implementation of this definition for regulatory purposes is conditioned by the large deviations between the results obtained by different sizing methods or due to practical reasons such as high costs and time-consuming. For most measurement methods for particle size determination it is necessary to initially disperse the particles in a suitable liquid. However, as the particle size decreases, the adhesion forces increase strongly, making it more difficult to deagglomerate the particles and to assess accurately the result of this process. Therefore, the success of the deagglomeration process substantially determines the measurement uncertainty and hence, the comparability between different methods. Many common methods such as dynamic light scattering (DLS), centrifugal liquid sedimentation (CLS) or ultrasound attenuation spectroscopy (US) can give good comparable results for the size of nanoparticles, if they are properly separated and stabilized (e.g. in reference suspensions). In order to avoid the use of hardly available and expensive methods such as SEM / TEM for all powders, an agglomeration-tolerant screening method is useful. One of the measurement methods well suited to probe the size of particulate powder is the determination of the volume-specific surface area (VSSA) by means of gas adsorption as well as skeletal density. The value of 60 m2/cm3 corresponding to spherical, monodisperse particles with a diameter of 100 nm constitutes the threshold for decisioning if the material is a nano- or non-nanomaterial. The identification of a nanomaterial by VSSA method is accepted by the EU recommendation. However, the application of the VSSA method was associated also with some limitations. The threshold of 60 m2/cm3 is dependent on the particle shape, so that it changes considerably with the number of nano-dimensions, but also with the degree of sphericity of the particles. For particles containing micro-pores or having a microporous coating, false positive results are induced. Furthermore, broad particle size distributions made necessary to additionally correct the threshold. Based on examples of commercially available ceramic powders, the applicability of the VSSA approach was tested in relation with SEM and TEM measurements. The introduction of a correction term for deviations from sphericity and further additions improved the applicability of VSSA as a screening method. T2 - Partec CY - Nuremberg, Germany DA - 09.04.2019 KW - VSSA KW - Nanoparticles PY - 2019 AN - OPUS4-47874 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Koclega, Damian A1 - Radziszewska, A. A1 - Dymek, S. A1 - Kranzmann, Axel T1 - Corrosion behaviour of Ni-Cr-Mo-W coatings in environments containing sulfur N2 - The ferritic steel 13CrMo4-5 due to good properties with relation to attractive price is frequently use in power plants industry. According EN10028-2 this steel can be used up to 570 °C because of its creep behavior but its corrosion resistance limits the use frequently to lower temperatures, depending on gas temperature and slag formation. The corrosion test were performed in environment containing mixture of gases like: O2, COx, SOx and ashes, with elements e.g. Na, Cl, Ca, Si, C, Fe, Al. Exposure time was respectively 240 h, 1000 h and 4500 h in temperature 600 °C. The oxide scale on the 13CrMo4-5 steel was significant thicker than for In686 coating and the difference increase according for longer exposure time. The microstructure, chemical and phase composition of the oxide scales were investigated by means of a light microscope, the electron scanning and transmission microscopes (SEM,TEM) equipped with the EDS detectors. T2 - Gordon Research Conference CY - New London, New Hampshire, USA DA - 21.07.2019 KW - High temperature KW - Corrosion resistance KW - Laser cladding KW - Inconel 686 KW - Aggressive environment PY - 2019 AN - OPUS4-49358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kranzmann, Axel A1 - Midtlyng, Jan A1 - Schlitte, I.-V. A1 - Escoda de Pablo, S. T1 - Corrosion of VM12 SHC in Salt melt N2 - Alkali and alkaline earth chlorides are discussed as heat storage media and are characterized by their low price and high availability. Disadvantages are a high corrosion rate and formation of Cr6+ ions in the melt, as observed in various binary chlorine salt melts. In our work the system NaCl-KCl-MgCl2 is considered. The storage capacity in this salt system is between 2 and 3 MWh per 10 t salt, depending on composition, melting temperature and working temperature. At the same time the system offers a eutectic line, which allows a high variance of the composition and possibly different corrosion rates can be observed. Corrosion tests in melts were carried out and the corrosion layers investigated. The tests with chloride melts on 12% Cr steel show an inner corrosion zone of up to 40 µm depth after 96 hours. The corrosion mechanisms and potential solutions are discussed. T2 - EUROCORR 2019 CY - Sevilla, Spain DA - 09.09.2019 KW - Salt melt KW - Corrosion KW - VM12 SHC PY - 2019 AN - OPUS4-50759 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -