TY - JOUR A1 - Moldenhauer, Laura A1 - Helmerich, Rosemarie A1 - Köppe, Enrico A1 - Haamkens, Frank A1 - Wittmann, Jochen ED - Emri, Igor T1 - Experimental feasibility study about moisture in building materials measured with Bluetooth JF - Materials Today: Proceedings N2 - Structural health monitoring contributes to early damage detection in the built infrastructure. During the last two decades, sensor networks transferred from wired to wireless sensor networks. Several methods exist to measure moisture in building materials. Most of the introduced commercial moisture measurement methods provide information about the local or near surface moisture. A feasibility study is presented to demonstrate, how the Received Signal Strength Indicator (RSSI) of a Bluetooth Low Energy (BLE) signal, transmitted from the BLE-module embedded in building materials, correlate with changing moisture content. The feasibility of this influence was investigated in the presented study. The maximum and minimum RSSI were systematically recorded and analysed. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portoroz, Slovenia DA - 20.09.2016 KW - BLE KW - Long-Term Monitoring KW - Network KW - Structural Health Monitoring KW - Moisture Measurement KW - RSSI KW - Bluetooth Low Energy KW - Sensor PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308398 DO - https://doi.org/10.1016/j.matpr.2017.06.053 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5889 EP - 5892 PB - Elsevier Ltd. AN - OPUS4-41585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sun, C. A1 - Tian, X. A1 - Wang, L. A1 - Liu, Y. A1 - Wirth, Cynthia A1 - Günster, Jens A1 - Li, D. A1 - Jin, Z. T1 - Effect of particle size gradation on the performance of glass-ceramic 3D printing process JF - Ceramics International N2 - Particle size gradation is regarded as an effective method for overcoming the contradicting requirements in three-dimensional printing (3DP). In present work, particle size gradation was optimized to obtain both acceptable flowability of the powder material and high-strength 3D-printed glass-ceramic products. The effect of gradation on the printing process, sintering process and performance of the 3D-printed glass-ceramic products was investigated comprehensively. The glass-ceramic powders with three size ranges were mixed in certain proportions and applied to print parts. The result showed parts printed with powder mixed by 60 wt% 45–100 µm and 40 wt% 0–25 µm particles had satisfactory density of 1.60 g/cm³ and bending strength of 13.8 MPa. The flowability decreased with an increasing proportion of fine particles. Part density was determined by the powder bulk density in the powder bed as well as the shrinkage during sintering while strength of part was found to be dependent on the sintering degree. KW - Flowability KW - Glass-ceramic KW - Particle size gradation KW - Three-dimensional printing KW - Mechanical properties PY - 2017 DO - https://doi.org/10.1016/j.ceramint.2016.09.197 SN - 0272-8842 VL - 43 IS - 1 SP - 578 EP - 584 PB - Elsevier AN - OPUS4-39783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mady, A. H. A1 - Baynosa, M. L. A1 - Tuma, Dirk A1 - Shim, J.-J. T1 - Facile microwave-assisted green synthesis of Ag-ZnFe2O4@rGO nanocomposites for efficient removal of organic dyes under UV- and visible-light irradiation JF - Applied Catalysis B: Environmental N2 - Nanocomposites of Ag-ZnFe2O4@reduced graphene oxide (rGO) were synthesized using a one-pot microwave-assisted self-assembly method. The morphology and structure of the Ag-ZnFe2O4@rGO nanocomposites were characterized. The nanocomposites formed with 15.2 wt% rGO showed excellent adsorption properties and high photocatalytic activity for the degradation of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO). The synergistic interactions between Ag, ZnFe2O4, and rGO decreased the aggregation of the nanoparticles (NPs) and increased the surface area, resulting in better absorption in both UV and visible light. Such a structure was helpful for separating the photoexcited electron-hole pairs and accelerating electron transfer. Electrochemical impedance spectroscopy (EIS) revealed a smaller resistance in the solid-state interface layer and charge transfer on the composite surface than that of the bare ZnFe2O4 NPs and ZnFe2O4@rGO nanocomposite. The Ag-ZnFe2O4@rGO nanocomposite could be recovered easily by a magnet and reused five times with no significant decrease in photocatalytic activity. The as-prepared Ag-ZnFe2O4@rGO nanocomposite catalyst could be applied to the removal of hard-to-degrade waste materials owing to its high efficiency in both UV and visible light and its excellent reusability. KW - nanoparticles KW - microwave synthesis KW - photocatalysis PY - 2017 DO - https://doi.org/10.1016/j.apcatb.2016.10.033 SN - 0926-3373 SN - 1873-3883 VL - 203 SP - 416 EP - 427 PB - Elsevier B. V. CY - Amsterdam AN - OPUS4-37962 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Vormwald, M. T1 - Fatigue strength and fracture mechanics JF - Procedia Structural Integrity N2 - If fracture mechanics shall be applied to the total lifetime respectively the fatigue limit of components (within the meaning of the S-N curve approach) it has to address four challenges: (a) It has to adequately describe so-called short crack propagation, which cannot be based on the common long crack concepts for principle reasons. Since the crack size is in the order of the plastic zone size, the modelling of short crack propagation cannot be based on the common linear elastic Delta K concept. Instead, an elastic-plastic parameter such as the cyclic J integral has to be applied. A second point is that the crack closure concept has to be modified in that the crack opening stress is not a constant, crack size- independent parameter but shows a transient behaviour with increasing short crack size. (b) It has to provide a meaningful definition of the initial crack dimensions as the starting point for an S-N curve relevant (residual) lifetime analysis. This can be based either on the (statistical) size of material defects which can be treated as cracks or by the size of the crack which would arrest subsequent to early crack propagation, whatever is larger. (c) It has to cope with the problem of multiple cracks for load levels higher than the fatigue limit such as it occurs in many applications in the absence of very large initial defects. (d) This requires consequent statistical treatment taking into account variations in the local geometry of the area where crack initiation has to be expected as well as the scatter in the initial crack size and in the material data used for the analyses. T2 - 2nd International Conference on Structural Integrity CY - Funchal, Madeira, Portugal DA - 04.09.2017 KW - Fatigue strength KW - Fracture mechanics KW - Initial crack size KW - Short crack propagation KW - Multiple crack propagation PY - 2017 DO - https://doi.org/10.1016/j.prostr.2017.07.065 SN - 2452-3216 VL - 5 SP - 745 EP - 752 AN - OPUS4-42545 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zerbst, Uwe A1 - Madia, Mauro A1 - Beier, H. Th. T1 - Fatigue strength and life determination of weldments based on fracture mechanics JF - 3rd international Symposium on fatigue design and material defects (FDMD 2017) N2 - The paper provides an overview on the results of a German cluster project on the use of fracture mechanics to the determination of the fatigue strength of weldments with fatigue cracks originating at the weld toes. The approach includes (a) a concept for short crack propagation for which the common ΔK concept is not applicable and the crack closure effects are still being gradually build-up, (b) a method for determining fatigue life relevant initial crack sizes as they are needed in any fracture mechanics analysis and (c) multiple cracking and crack coalescence at load levels higher than the endurance limit. The analyses are stochastically performed. Both, the endurance limit and the finite life branch of the S-N curve are determined. Besides a brief introduction into the approach, validation examples are presented. These comprise different weldment types (butt welds, cross joints and longitudinal stiffened plates), two steels (S355NL and S960QL) of quite different strengths, different weld geometries due to different welding techniques (WIG, MAG), as-welded and stress relieved welds and different stress ratios varying from R = -1 to R = 0.5. T2 - FDMD 2017 CY - Lecco, Italy DA - 19.09.2017 KW - Weldments KW - Fatigue strength KW - Fracture mechanics KW - Initial crack size KW - Short crack propagation KW - Multiple crack propagation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-438500 DO - https://doi.org/10.1016/j.prostr.2017.11.106 SN - 2452-3216 VL - 7 SP - 407 EP - 414 PB - ScienceDirect CY - Lecco, Italy AN - OPUS4-43850 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Leonhard, H. T1 - Fehlstellen im Visier - KorroPads JF - PROCESS N2 - Rohrsysteme und Behälter aus nichtrostendem Stahl sind mit einer Passivschicht vor Korrosion geschützt. Ist diese jedoch unvollständig ausgebildet oder beschädigt, geht der Schutz verloren. Das KorroPad-Verfahren ist ein Schnelltest zur Überprüfung der Passivschicht. Im Vergleich mit bisher üblichen Bewertungsmethoden ist die Anwendung sehr einfach und nimmt nur 15 Minuten in Anspruch. KW - Nichtrostender Stahl KW - Korrosionsschnelltest KW - KorroPad KW - Passivschicht PY - 2017 SN - 0946-2856 VL - 24 IS - 11/12 SP - 66 EP - 67 PB - Vogel Business Media GmbH & Co. KG CY - Würzburg AN - OPUS4-43184 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heitz, J. A1 - Plamadeala, C. A1 - Muck, M. A1 - Armbruster, O. A1 - Baumgartner, W. A1 - Weth, A. A1 - Steinwender, C. A1 - Plessberger, H. A1 - Kellermair, J. A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Guntner, A. S. A1 - Hassel, A. W. T1 - Femtosecond laser-induced microstructures on Ti substrates for reduced cell adhesion JF - Applied Physics A N2 - Miniaturized pacemakers with a surface consisting of a Ti alloy may have to be removed after several years from their implantation site in the heart and shall, therefore, not be completely overgrown by cells or tissue. A method to avoid this may be to create at the surface by laser-ablation self-organized sharp conical spikes, which provide too little surface for cells (i.e., fibroblasts) to grow on. For this purpose, Ti-alloy substrates were irradiated in the air by 790 nm Ti:sapphire femtosecond laser pulses at fluences above the ablation threshold. The laser irradiation resulted in pronounced microstructure formation with hierarchical surface morphologies. Murine fibroblasts were seeded onto the laser-patterned surface and the coverage by cells was evaluated after 3–21 days of cultivation by means of scanning electron microscopy. Compared to flat surfaces, the cell density on the microstructures was significantly lower, the coverage was incomplete, and the cells had a clearly different morphology. The best results regarding suppression of cell growth were obtained on spike structures which were additionally electrochemically oxidized under acidic conditions. Cell cultivation with additional shear stress could reduce further the number of adherent cells. KW - Laser Processing KW - Femtosecond laser KW - Titanium alloy KW - Cell adhesion KW - Anodic oxidation KW - Pacemaker PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-427681 UR - https://link.springer.com/article/10.1007/s00339-017-1352-0 DO - https://doi.org/10.1007/s00339-017-1352-0 SN - 0947-8396 SN - 1432-0630 VL - 123 IS - 12 SP - 734, 1 EP - 9 PB - Springer-Verlag CY - Berlin AN - OPUS4-42768 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Kirner, Sabrina A1 - Koter, Robert A1 - Pentzien, Simone A1 - Spaltmann, Dirk A1 - Krüger, Jörg T1 - Femtosecond laser-induced periodic surface structures on titanium nitride coatings for tribological applications JF - Applied Surface Science N2 - Titanium nitride (TiN) was coated on different substrate materials, namely pure titanium (Ti), titanium alloy (Ti6Al4V) and steel (100Cr6), generating 2.5 μm thick TiN layers. Using femtosecond laser pulses (30 fs, 790 nm, 1 kHz pulse repetition rate), large surface areas (5 mm × 5 mm) of laser-induced periodic surface structures (LIPSS) with sub-wavelength periods ranging between 470 nm and 600 nm were generated and characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). In tribological tests, coefficients of friction (COF) of the nanostructured surfaces were determined under reciprocating sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel during 1000 cycles using two different lubricants, namely paraffin oil and engine oil. It turned out that the substrate material, the laser fluence and the lubricant are crucial for the tribological performance. However, friction and wear could not be significantly reduced by LIPSS on TiN layers in comparison to unstructured TiN surfaces. Finally, the resulting wear tracks on the nanostructured surfaces were investigated with respect to their morphology (OM, SEM), depth (WLIM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and, on one hand, compared with each other, on the other hand, with non-structured TiN surfaces. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser ablation KW - Titanium nitride films KW - Friction KW - Wear PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216322486 DO - https://doi.org/10.1016/j.apsusc.2016.10.132 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 572 EP - 579 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40507 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröder, Volkmar A1 - Molnarne, Maria T1 - Flammability of gases in focus of European and US standards JF - Journal of Loss Prevention in the Process Industries N2 - The presentation will discuss the difference between EU and US standards for the determination of explosion (flammability) limits and limiting oxygen concentration. Small differences observed in measured values can be traced back to the different test apparatuses and criteria. The discrepancies can be much greater in the case of limiting oxygen concentration because of the high amount of inert gases and the corresponding low laminar burning velocities. The paper describes some examples and the influence of the chosen criteria on the results. The European and US standards use the criteria of flame propagation in open test vessels and of pressure rise in closed ones. The examples discussed show that flame propagation is still possible at very small pressure rise values, as observed much below the pressure rise criterion of usual standards. However, flame propagation in a process plant can cause an accident or explosion and must be avoided. Therefore, the flame propagation criterion is recommended to be used in chemical safety engineering. The European safety database CHEMSAFE contains expertevaluated safety data for cases where the determination method and criteria are known. Flammability characteristics based on the pressure rise criterion may suffice in certain cases, e.g. for explosion protection in closed vessels without any connecting pipes. KW - Flammability KW - Limiting oxygen concentration KW - Test methods KW - Standards PY - 2017 DO - https://doi.org/10.1016/j.jlp.2017.05.012 SN - 0950-4230 SN - 1873-3352 VL - 48 SP - 297 EP - 304 PB - Elsevier CY - Amsterdam AN - OPUS4-40980 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cappella, Brunero T1 - Force-distance curves on lubricant films: An approach to the characterization of the shape of the AFM tip JF - Micron N2 - Force-distance curves have been acquired with an atomic force microscope on perfluorpolyether films. It is shown that curves acquired on films of different thickness, at different rates and with different dwell times can be overlapped by rescaling the time or distance axis.When the time or distance axis is rescaled,the force depends only on the surface tension of perfluorpolyether and on geometrical properties of thetip (aperture and perimeter of the tip at a given distance from the apex). Hence, curves acquired with thesame tip overlap. By comparing curves acquired at different rates the dynamics of tip-wetting can be investigated. Fur-thermore, rescaled force-distance curves have been matched with the perimeter of cross sections ofthe tip, i.e. with the perimeter of the three-phase contact line. Such measurements pave the way for anon-destructive investigation of the tip shape. KW - Lubricant films KW - Surface tension KW - Atomic force microscopy KW - Force-distance curves KW - AFM tip shape PY - 2017 DO - https://doi.org/10.1016/j.micron.2016.11.006 SN - 0968-4328 VL - 93 SP - 20 EP - 28 AN - OPUS4-38391 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Olejko, Lydia A1 - Bald, Ilko T1 - FRET efficiency and antenna effect in multi-color DNA origami-based light harvesting systems JF - RSC Advances N2 - Artificial light harvesting complexes find applications in artificial photosynthesis, photovoltaics and light harvesting chemical sensors. They are used to enhance the absorption of light of a reaction center which is often represented by a single acceptor. Here, we present different light harvesting systems on DNA origami structures and analyze systematically the light harvesting efficiency. By changing the number and arrangement of different fluorophores (FAM as donor, Cy3 as transmitter and Cy5 as acceptor molecules) the light harvesting efficiency is optimized to create a broadband absorption and to improve the antenna effect 1 (including two energy transfer steps) from 0.02 to 1.58, and the antenna effect 2 (including a single energy transfer step) from 0.04 to 8.7, i.e. the fluorescence emission of the acceptor is significantly higher when the light-harvesting antenna is excited at lower wavelength compared to direct excitation of the acceptor. The channeling of photo energy to the acceptor proceeds by Förster Resonance Energy Transfer (FRET) and we carefully analyze also the FRET efficiency of the different light harvesting systems. Accordingly, the antenna effect can be tuned by modifying the stoichiometry of donor, transmitter and acceptor dyes, whereas the FRET efficiency is mainly governed by the spectroscopic properties of dyes and their distances. KW - DNA origami KW - Light-harvesting KW - FRET KW - Antenna effect PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-405867 UR - http://pubs.rsc.org/en/content/articlelanding/2017/ra/c7ra02114c#!divAbstract DO - https://doi.org/10.1039/C7RA02114C VL - 7 IS - 39 SP - 23924 EP - 23934 PB - The Royal Soc. of Chemistry AN - OPUS4-40586 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilling, Markus A1 - Niebergall, Ute A1 - Böhning, Martin T1 - Full notch creep test (FNCT) of PE-HD – Characterization and differentiation of brittle and ductile fracture behavior during environmental stress cracking (ESC) JF - Polymer Testing N2 - The damage mechanisms slow crack growth (SCG) and environmental stress cracking (ESC), relevant for PE-HD materials are characterized based on improved full notch creep testing (FNCT) of two selected typical PE-HD materials for container applications. In this context, a distinction of the failure mechanisms as well as a categorization of involved media is suggested. Employing a novel FNCT device, elongation data were obtained in addition to conventional time-to-failure results of stress-dependent as well as temperature-dependent measurements. Changes in failure behavior, as determined by fracture surface analysis based on light microscopy (LM) and laser scanning microscopy (LSM), are correlated with FNCT results and used to introduce an additional possibility for the identification of brittle/ductile fracture behavior. KW - Environmental stress cracking (ESC) KW - Slow crack growth (SCG) KW - Full notch creep test (FNCT) KW - High-density polyethylene (PE-HD) PY - 2017 DO - https://doi.org/10.1016/j.polymertesting.2017.09.043 SN - 0142-9418 SN - 1873-2348 VL - 64 SP - 156 EP - 166 PB - Elsevier CY - Amsterdam AN - OPUS4-42484 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas T1 - Gleitverhalten von PEEK-Kompositwerkstoffen in Wasserstoffumgebung JF - Tribologie + Schmierungstechnik N2 - Die Reibeigenschaften von PEEK Materialien gegen Stahlscheiben wurden in Luft, Vakuum und Wasserstoffumgebung untersucht. KW - PEEK-Komposite KW - Wasserstoff KW - Vakuum KW - Graphit PY - 2017 SN - 0724-3472 VL - 64 IS - 6 SP - 52 EP - 59 AN - OPUS4-42919 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heck, Christian A1 - Prinz, Julia A1 - Dathe, A. A1 - Merck, V. A1 - Stranik, O. A1 - Fritzsche, W. A1 - Kneipp, Janina A1 - Bald, Ilko T1 - Gold nanolenses self-assembled by DNA origami JF - ACS Photonics N2 - Nanolenses are self-similar chains of metal nanoparticles, which can theoretically provide extremely high field enhancements. Yet, the complex structure renders their synthesis challenging and has hampered closer analyses so far. Here, DNA origami is used to self-assemble 10, 20, and 60 nm gold nanoparticles as plasmonic gold nanolenses (AuNLs) in solution and in billions of copies. Three different geometrical arrangements are assembled, and for each of the three designs, surface-enhanced Raman scattering (SERS) capabilities of single AuNLs are assessed. For the design which shows the best properties, SERS signals from the two different internal gaps are compared by selectively placing probe dyes. The highest Raman enhancement is found for the gap between the small and medium nanoparticle, which is indicative of a cascaded field enhancement. KW - DNA origami KW - SERS KW - Gold nanoparticles KW - Plasmonics PY - 2017 UR - http://pubs.acs.org/doi/pdf/10.1021/acsphotonics.6b00946 DO - https://doi.org/10.1021/acsphotonics.6b00946 SN - 2330-4022 VL - 4 IS - 5 SP - 1123 EP - 1130 AN - OPUS4-40587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Chandra, K. A1 - Kranzmann, Axel T1 - High temperature oxidation of 9–12% Cr ferritic/martensitic steels under dual-environment conditions JF - Corrosion engineering, science and technology N2 - In normal operations, the opposite surfaces of the power plant components are exposed to two different environments, i.e. air/flue gas on the one side and steam on the other side. Exposure under such dual-environment can lead to accelerated corrosion of the components on the air side. The oxidation behaviour of ferritic/martensitic steel T92 was investigated under dual-environment in a specially designed test equipment. The samples were exposed to dry oxyfuel flue gas (CO2–27%N2–2%O2–1%SO2) on one side and to steam on the other side up to 1000 h at 650°C. The formation of oxide scales was characterised by optical microscopy and scanning electron microscopy with attached energy-dispersive spectroscopy. Oxidation rate of specimens under dual-Environment condition was almost three times higher than that in single-environment condition. This is explained based on hydrogen transport through the bulk alloy from the steam side to the flue gas side. KW - Oxidation KW - Dual-environment KW - Oxyfuel KW - Ferritic/martensitic steel KW - Steam PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-457101 DO - https://doi.org/10.1080/1478422X.2017.1374049 VL - 53 IS - 31 SP - 27 EP - 33 PB - Taylor & Francis AN - OPUS4-45710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gook, S. A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Hybrid laser arc welding of high grade X80 and X120 pipeline steels JF - Global Nuclear Safety N2 - The aim of the present work was to investigate the possibilities of hybrid laser arc welding regarding reliable production of longitudinal welds of high strength pipe steels X80 and X120 and to evaluate achievable mechanical properties of laser hybrid welds. The study focused on weld toughness examination in low temperature range up to -60 °C. SЮТЭКЛХО ПТХХОЫ ЦКЭОЫТКХЬ were identified in the context of this task. It could be shown that metal cored electrodes guaranteed sufficient Charpy impact toughness at low temperature for both investigated materials. Modern arc welding technologies such as modified pulsed spray arc were used to promote deeper Penetration of the filler material into the narrow laser welding gap. Edge preparation with a 14 mm deep root face was considered as optimum, because no penetration of the filler material could be detected beyond this depth limit and therefore any metallurgical influences on the weld metal properties through the welding wire could be excluded. KW - High strength steel KW - Longitudinal weld KW - Modified spray arc KW - Pipeline KW - Hybrid laser arc welding PY - 2017 SN - 2499-9733 SN - 2305-414Х VL - 1 IS - 22 SP - 21 EP - 35 AN - OPUS4-44343 LA - rus AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhang, Rui A1 - Russo, Patrícia A. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Jeon, Taeyeol A1 - Pinna, Nicola T1 - Hybrid organic–inorganic transition-metal phosphonates as precursors for water oxidation electrocatalysts JF - Advanced Functional Materials N2 - Efficient water oxidation catalysts are required for the development of water splitting technologies. Herein, the synthesis of layered hybrid NiFephenylphosphonate compounds from metal acetylacetonate precursors and phenylphosphonic acid in benzyl alcohol, and their Oxygen evolution reaction performance in alkaline medium, are reported. The hybrid particles are formed by inorganic layers of NiO6 and FeO6 distorted octahedra separated by bilayers of the organic group, and template the Formation in situ of NiFe hydroxide nanosheets of sizes between 5 and 25 nm and thicknesses between 3 and 10 nm. X-ray absorption spectroscopy measurements suggest that the hybrid also acts as a template for the local structure of the metal sites in the active catalyst, which remain distorted after the transformation. Optimum electrocatalytic activity is achieved with the hybrid compound with a Fe content of 16%. The combination of the synergistic effect between Ni and Fe with the structural properties of the hybrid results in an efficient catalyst that generates a current density of 10 mA cm−2 at an overpotential of 240 mV, and also in a stable catalyst that operates continuously at low overpotentials for 160 h. KW - Water oxydation catalysis KW - EXAFS PY - 2017 DO - https://doi.org/10.1002/adfm.201703158 SN - 1616-301X SN - 1616-3028 VL - 27 IS - 40 SP - Article 1703158, 1 EP - 11 PB - WILEY-VCH Verlag CY - Weinheim AN - OPUS4-42783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Silverstein, R. A1 - Sobol, Oded A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang A1 - Eliezer, D. T1 - Hydrogen behavior in SAF 2205 duplex stainless steel JF - Journal of Alloys and Compounds N2 - This paper describes austenitic-ferritic duplex stainless steels, SAF 2205, in the presence of hydrogen. The duplex stainless steels (DSS) properties include excellent resistance to stress corrosion cracking, high strength and good weldability. Those steels are preferably used in industries combining hydrogen and loads. Hydrogen location in addition to hydrogen binding energy with the steel's defects are of great importance for the analysis of hydrogen embrittlement model in that steel. It is known from previously published works that the susceptibility to hydrogen embrittlement will depend on the competition between reversible and irreversible traps; meaning a direct relation to the hydrogen's state and position in the steel. In this work, we examine the local hydrogen concentration, trapping and distribution by two modern and advanced techniques: thermal desorption spectrometry (TDS) and we support it by time of flight-secondary ion mass spectrometer (ToF-SIMS). In this paper, we support and give for the first time new insights and better understanding to the hydrogen embrittlement mechanism in SAF 2205. The trapping energies levels were calculated using TDS and Lee and Lee's model. This model revealed reversible in addition to irreversible trapping sites. Also the trapping controlling mechanism was found to be a combination of detrapping controlled mechanism and diffusion controlled mechanism. The use of ToF-SIMS for local imaging the distribution of hydrogen species supports the discussion of the different hydrogen traps in this type of steel. The hydrogen embrittlemet phenomenon in SAF 2205 will be discussed in details in that paper. KW - Hydrogen trapping KW - Duplex stainless steel KW - Thermal desorption spectrometry (TDS) KW - ToF-SIMS PY - 2017 DO - https://doi.org/10.1016/j.jallcom.2016.11.184 SN - 0925-8388 SN - 1873-4669 VL - 695 SP - 2689 EP - 2695 PB - Elsevier B.V. AN - OPUS4-38856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Omara, Shereen Shabaan A1 - Turky, G. A1 - Ghoneim, A. A1 - Thünemann, Andreas A1 - Abdel Rehim, M. H. A1 - Schönhals, Andreas T1 - Hyperbranched poly(amidoamine)/kaolinite nanocomposites: Structure and charge carrier dynamics JF - Polymer N2 - An ex-situ approach was applied to prepare nanocomposites from hyperbranched poly(amidoamine) and modified kaolinite (Ka-DCA). The structure of the polymer and the corresponding nanocomposites was investigated by FTIR, DSC, SAXS and TEM. SAXS might suggest a partly exfoliated structure of the nanocomposites, which was supported by TEM. The molecular dynamics was studied by means of broadband dielectric spectroscopy (BDS). The dielectric spectra are dominated by a conductivity contribution at higher temperatures for all samples investigated. The obtained results further indicated that DC conductivity is increased by 4 orders of magnitude with increasing concentration of Ka-DCA nanofiller. Further, a significant separation between the conductivity relaxation time and that of segmental dynamics was observed. The decoupling phenomenon and the conductivity mechanism were discussed in detail. This study provides insights about the influence of the nanofiller on the structure and the conductivity contribution of nanocomposites of hyperbranched polymers including the decoupling phenomenon and fragility. KW - Hyperbranched polymers KW - Nanocomposites KW - Conductivity PY - 2017 DO - https://doi.org/10.1016/j.polymer.2017.06.017 SN - 0032-3861 VL - 121 SP - 64 EP - 74 PB - Elsevier Ltd. AN - OPUS4-40648 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sieg, H. A1 - Kästner, Claudia A1 - Krause, B. A1 - Meyer, T. A1 - Burel, A. A1 - Böhmert, L. A1 - Lichtenstein, D. A1 - Jungnickel, H. A1 - Tentschert, J. A1 - Laux, P. A1 - Braeuning, A. A1 - Estreal-Lopis, I. A1 - Gauffre, F. A1 - Fessard, V. A1 - Meijer, J. A1 - Luch, A. A1 - Thünemann, Andreas A1 - Lampen, A. T1 - Impact of an artificial digestion procedure on aluminum-containing nanomaterials JF - Langmuir N2 - Aluminum has gathered toxicological Attention based on relevant human exposure and its suspected hazardous potential. Nanoparticles from food supplements or Food contact materials may reach the human gastrointestinal tract. Here, we monitored the physicochemical fate of aluminum containing nanoparticles and aluminum ions when passaging an in vitro model of the human gastrointestinal tract. Smallangle X-ray scattering (SAXS), transmission electron microscopy (TEM), ion beam microscopy (IBM), secondary ion beam mass spectrometry (TOF-SIMS), and inductively coupled plasma mass spectrometry (ICP-MS) in the singleparticle mode were employed to characterize two aluminumcontaining nanomaterials with different particle core materials (Al0, γAl2O3) and soluble AlCl3. Particle size and shape remained unchanged in saliva, whereas strong Agglomeration of both aluminum nanoparticle species was observed at low pH in gastric fluid together with an increased ion release. The levels of free aluminum ions decreased in intestinal fluid and the particles deagglomerated, thus liberating primary particles again. Dissolution of nanoparticles was limited and substantial changes of their shape and size were not detected. The amounts of particle-associated phosphorus, chlorine, potassium, and calcium increased in intestinal fluid, as compared to nanoparticles in standard dispersion. Interestingly, nanoparticles were found in the intestinal fluid after addition of ionic aluminum. We provide a comprehensive characterization of the fate of aluminum nanoparticles in simulated gastrointestinal fluids, demonstrating that orally ingested nanoparticles probably reach the intestinal epithelium. The balance between dissolution and de novo complex formation should be considered when evaluating nanotoxicological experiments. KW - Small-angle X-ray scattering KW - SAXS KW - Nanoparticle PY - 2017 DO - https://doi.org/10.1021/acs.langmuir.7b02729 SN - 1520-5827 SN - 0743-7463 VL - 33 IS - 40 SP - 10726 EP - 10735 PB - Americal Chemical Society AN - OPUS4-42438 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rodrigues, A.C.P. A1 - Österle, Werner A1 - Gradt, Thomas A1 - Azevedo, César Roberto de Farias T1 - Impact of copper nanoparticles on tribofilm formation determined by pin-on-disc tests with powder supply: Addition of artificial third body consisting of Fe3O4, Cu and graphite JF - Tribology International N2 - Copper, magnetite and graphite particles were mixed in order to observe their impact on the coefficient of friction (CoF) during pin-on-disc tests and on the tribofilm formation after testing. Pure magnetite powder provided a value of CoF of 0.4. Magnetite-copper mixtures tested at 400 °C revealed lower CoF values (~0.4) than those at room temperature (~0.6). Magnetite-graphite and magnetite-graphite-copper mixtures presented lower CoF values (~0.3). All systems formed a magnetite-based tribofilm and patches of metallic copper were found on the tribosurfaces of the mixtures containing copper. Carbon layers and graphite nanoinclusions were observed in the graphite mixtures. The incorporation of zirconia particles, a by-product of ball milling mixing, prevented the selective transfer of graphite and copper to the tribosurfaces of some of the samples. KW - Brake pad materials KW - Sliding friction KW - Transfer layer KW - Surface analysis KW - Model friction tests PY - 2017 DO - https://doi.org/10.1016/j.triboint.2017.02.014 SN - 0301-679X VL - 110 SP - 103 EP - 112 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-40104 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kohler, C. A1 - Nikfalazar, M. A1 - Heunisch, Andreas A1 - Schulz, Bärbel A1 - Mikolajek, M. A1 - Rabe, Torsten A1 - Jakoby, R. A1 - Binder, J. T1 - Implementation of Ba0.6Sr0.4TiO3-ZnO-B2O3 based tunable microwave phase shifters in LTCC technology JF - International Journal of Applied Ceramic Technology N2 - Tunable dielectric Ba0.6Sr0.4TiO3-ZnO-B2O3 thick-films were analyzed regarding their integration potential into the LTCC technology. Therefore, tunable loaded line phase shifters based on metal-insulator-metal varactors with single- and double- printed BST thick-films were fabricated and co-sintered inside a four layer LTCC module. Microstructural and chemical investigations showed a sufficient compatibility and adhesion between the silver, BST composite and LTCC layers and a resulting morphology depending on the processing route. The microwave characterization of the LTCC-embedded phase shifters revealed comparable results to phase shifters with the same design on alumina substrates. KW - Thick films KW - Dielectric materials KW - Electroceramics PY - 2017 DO - https://doi.org/10.1111/ijac.12687 SN - 1546-542X SN - 1744-7402 VL - 14 IS - 4 SP - 574 EP - 582 PB - Wiley CY - Hoboken, NY, USA AN - OPUS4-41086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Vollert, J. A1 - Dixneit, Jonny A1 - Kromm, Arne A1 - Buslaps, Th. A1 - Kannengießer, Thomas T1 - In situ EDXRD study of MAG-welding using LTT weld filler materials under structural restraint JF - Materials Science Forum N2 - Welding using low transformation temperature (LTT) filler materials is an innovative approach to mitigate detrimental welding residual stresses without cost-intensive post weldtreatments. Due to the local Generation of compressive residual stresses in the weld line by means of a delayed martensite transformation a significant enhancement of the cold cracking resistance of highly stressed welded components can be expected. For the effective usage of These materials a deeper understanding of the microstructural evolution inside the weld material is necessary to determine the complex processes that cause the residual stress formation during welding. Solid-state phase transformation kinetics and the evolution of strain in LTT weld filler materials are monitored in-situ at the instrument ID15A at the ESRF in Grenoble, France. The transferability to real components is implemented by using a realistic MAG welding process under consideration of structural restraint. During welding of multilayer joints, the phase Transformation and phase specific strain evolution of each individual layer is investigated in transmission geometry by means of energy-dispersive X-ray diffraction EDXRD using high energy synchrotron Radiation with a counting rate of 2.5 Hz. The measurement results of a 10% Cr / 10% Ni LTT weld filler are compared to data monitored for the conventional weld filler material G89. The in-situ data clearly indicate a strong effect on the local strain evolution and the formation of compressive strain. This results from the restraint volume expansion during the postponed austenite to martensite transformation of the LTT weld filler, which counteracts the thermal shrinkage. In contrast, for the conventional weld filler material the thermal contraction strains lead to tensile residual strain during welding. Furthermore, the results of in-situ observation during welding Show that the transformation kinetic is dependent on the welding sequence. KW - High energy synchrotron diffraction KW - Low transformation temperature KW - Weld filler KW - Residual stress KW - Welding PY - 2017 DO - https://doi.org/10.4028/www.scientific.net/MSF.905.107 SN - 1662-9752 VL - 905 SP - 107 EP - 113 PB - Trans Tech Publications CY - Switzerland AN - OPUS4-41806 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mieller, Björn A1 - Rabe, Torsten A1 - Rangelov, V. T1 - In situ shrinkage measurement during pressure-assisted sintering of low temperature co-fired ceramic panels JF - International Journal of Applied Ceramic Technology N2 - Shrinkage measurements of miniaturized low temperature co-fired ceramics (LTCC) samples under load typically lead to collapsing of the samples, which hampers the characterization of shrinkage up to full densification. In this paper, a measurement setup is presented, which allows for in situ shrinkage measurements of practical, large LTCC panels during pressure-assisted sintering in a sintering press. The shrinkage behavior of two commercial LTCC systems (GreenTape 951 and Ceramtape GC) has been measured under loads of up to 1 MPa. No crushing of the specimens was observed and reproducible characterization of shrinkage up to full densification has been performed. Based on comparisons to thermomechanical analyzer measurements in this and other studies, it was found that the in situ approach is much better suited for shrinkage characterization of LTCC under load. Reproducibility and accuracy of the method are discussed and practical as well as more academic applications are proposed. KW - Shrinkage KW - Low temperature KW - Sinter/sintering PY - 2017 DO - https://doi.org/10.1111/ijac.12634 SN - 1546-542X SN - 1744-7402 VL - 14 IS - 2 SP - 245 EP - 251 AN - OPUS4-39327 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Obaton, A-F. A1 - Fain, J. A1 - Djemaï, M. A1 - Meinel, Dietmar A1 - Léonard, Fabien A1 - Mahé, E. A1 - Lécuelle, B. A1 - Fouchet, J-J. A1 - Bruno, Giovanni T1 - In vivo XCT bone characterization of lattice structured implants fabricated by additive manufacturing JF - Heliyon N2 - Several cylindrical specimens and dental implants, presenting diagonal lattice structures with different cell sizes (600, 900 and 1200 µm) were additively manufactured by selective laser melting process. Then they were implanted for two months in a sheep. After removal, they were studied by Archimedes’ method as well as X-ray computed tomography in order to assess the penetration of bone into the lattice. We observed that the additive manufactured parts were geometrically conform to the theoretical specifications. However, several particles were left adhering to the surface of the lattice, thereby partly or entirely obstructing the cells. Nevertheless, bone penetration was clearly visible. We conclude that the 900 µm lattice cell size is more favourable to bone penetration than the 1200 µm lattice cell size, as the bone penetration is 84 % for 900 µm against 54 % for 1200 µm cell structures. The lower bone penetration value for the 1200 µm lattice cell could possibly be attributed to the short residence time in the sheep. Our results lead to the conclusion that lattice implants additively manufactured by selective laser melting enable better bone integration. KW - Biomedical engineering KW - Dentistry KW - Medical imaging KW - X-ray computer tomography PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-418648 DO - https://doi.org/10.1016/j.heliyon.2017.e00374 SN - 2405-8440 IS - 3 SP - Article e00374, 1 EP - 21 PB - Elsevier Limited CY - 125 London Wall London, EC2Y 5AS United Kingdom AN - OPUS4-41864 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kömmling, Anja A1 - Jaunich, Matthias A1 - Pourmand, P. A1 - Wolff, Dietmar A1 - Gedde, U.W. T1 - Influence of ageing on sealability of elastomeric O-rings JF - Macromolecular Symposia N2 - At BAM, which is the federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes the assessment of the service lifetime of elastomeric seals that are part of the container lid system with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) up to 1.5 years. In order to assess sealability, O-rings are aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings are aged as well. Further methods characterising seal performance are compression stress relaxation (CSR) reflecting the loss of sealing force of a compressed seal over time, and compression set (CS) which represents the recovery behaviour of a seal after release from compression. Additionally, hardness is measured for information about the change of mechanical properties. The experimental results indicate that while hardness, CSR and CS show considerable degradation effects, the leakage rate stays relatively constant or even decreases until shrinkage combined with the loss of resilience of the aged seal leads to leakage. This demonstrates that static leakage rate, which is the only available direct seal performance criterion, has only limited sensitivity towards the degradation of the seal material. CS data is extrapolated using time-temperature shifts and Arrhenius graphs. An exemplary CS of 50 % would be reached after approx. 1.2, 17 and 29 years at 60 °C for HNBR, EPDM and FKM respectively. T2 - PolymerTec 2016 CY - Merseburg, Germany DA - 15.06.2016 KW - Compression KW - Leakage KW - Degradation KW - Rubber KW - Lifetime PY - 2017 DO - https://doi.org/10.1002/masy.201600157 SN - 1022-1360 SN - 1521-3900 VL - 373 IS - 1 SP - UNSP 1600157, 1 EP - 10 PB - WILEY-V C H VERLAG GMBH CY - Weinheim AN - OPUS4-40958 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rehmer, Birgit A1 - Skrotzki, Birgit A1 - Glaubitz, Steffen T1 - Influence of casting skin on fatigue lifetime of ferritic ductile cast iron JF - Materials Testing N2 - The fatigue behaviour of cast iron is usually investigated on machined specimens. Components of cast iron, however, have a casting skin; therefore the investigation of the influence of the casting skin on the lifetime is of interest. To study this influence isothermal fatigue tests were carried out on heat-resisting spheroidal graphite cast iron EN GJS SiMo 4.05 in 4–point-bending set-up at 400 °C. Specimens with and without casting skin were investigated comparatively. The number of cycles to failure was significantly lower for specimens with casting skin. Metallographic investigations underline the reduction of lifetime caused by casting skin. KW - Cast iron KW - Casting skin KW - Fatigue KW - Lifetime PY - 2017 SN - 0025-5300 VL - 59 IS - 1 SP - 5 EP - 10 PB - Carl Hanser Verlag CY - München AN - OPUS4-38929 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gollnow, C. A1 - Griesche, Axel A1 - Weidemann, Jens A1 - Kannengießer, Thomas T1 - Influence of external loads on a characteristic angle between grains and solidus line as an indicator for hot cracking susceptibility during GTA welding JF - Journal of Materials Processing Technology N2 - A long list of criteria determining the hot cracking susceptibility already exists. A main influence on solidification cracking can result from the design of the welded construction, i.e. from the influence of external loads. Using the Controlled Tensile Weldability (CTW) test, an external load hot cracking test, the influence of constant pre-load and different extension rates on the solidification cracking behavior of GTA (Gas Tungsten Arc) welds in an austenitic (AISI 309) and a ferritic (AISI 441) steel were investigated. Compared to specimens welded allowing free shrinkage and welded with an applied constant tensile pre-load, the specimens welded during the application of increasing tensile load show solidification cracks. In the weld seams, a characteristic angle α between the predominantly columnar grains and the fusion line can be observed. Specimens showing solidification cracks show a significantly larger angle α compared to the crack-free specimens. Based on these observations, the characteristic angle α is proposed as a new hot cracking criterion. KW - Hot cracking KW - External load test KW - Component design KW - Crack criterion KW - Grain growth PY - 2017 DO - https://doi.org/10.1016/j.jmatprotec.2016.08.013 VL - 239 SP - 172 EP - 177 PB - Elsevier AN - OPUS4-37278 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Epperlein, Nadja A1 - Menzel, Friederike A1 - Schwibbert, Karin A1 - Koter, Robert A1 - Bonse, Jörn A1 - Sameith, Janin A1 - Krüger, Jörg A1 - Toepel, Jörg T1 - Influence of femtosecond laser produced nanostructures on biofilm growth on steel JF - Applied Surface Science N2 - Biofilm formation poses high risks in multiple industrial and medical settings. However, the robust nature of biofilms makes them also attractive for industrial applications where cell biocatalysts are increasingly in use. Since tailoring material properties that affect bacterial growth or its inhibition is gaining attention, here we focus on the effects of femtosecond laser produced nanostructures on bacterial adhesion. Large area periodic surface structures were generated on steel surfaces using 30-fs laser pulses at 790 nm wavelength. Two types of steel exhibiting a different corrosion resistance were used, i.e., a plain structural steel (corrodible) and a stainless steel (resistant to corrosion). Homogeneous fields of laser-induced periodic surface structures (LIPSS) were realized utilizing laser fluences close to the ablation threshold while scanning the sample under the focused laser beam in a multi-pulse regime. The nanostructures were characterized with optical and scanning electron microscopy. For each type of steel, more than ten identical samples were laser-processed. Subsequently, the samples were subjected to microbial adhesion tests. Bacteria of different shape and adhesion behavior (Escherichia coli and Staphylococcus aureus) were exposed to laser structures and to polished reference surfaces. Our results indicate that E. coli preferentially avoids adhesion to the LIPSS-covered areas, whereas S. aureus favors these areas for colonization. KW - Laser-induced periodic surface structures KW - Femtosecond laser KW - Steel KW - Biofilms KW - Microbial adhesion tests PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433217305470 DO - https://doi.org/10.1016/j.apsusc.2017.02.174 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 420 EP - 424 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-40565 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neubert, S. A1 - Pittner, Andreas A1 - Rethmeier, Michael T1 - Influence of non-uniform martensitic transformation on residual stresses and distortion of GMA-welding JF - Journal of Constructional Steel Research N2 - A combined experimental and numerical approach is applied for a numerical analysis of the non-uniform martensitic transformation kinetic on welding residual stresses and distortion of a single pass weld. The (γ → α)-transformation kinetic within the weld pool region is governed by a non-uniform distribution of the elements chromium and nickel. The single-pass weld was performed by use of the low-alloyed high-strength steel S960QL with the high-alloyed high-strength filler wire CN 13/4-IG®. A thermo-mechanical FE model of the welding process was experimentally validated against temperature field, solid phase distribution, transformation behaviour, X-Ray stress measurements and transient optical distortion measurements. The experimentally determined and calculated weld residual stresses and transient distortion are in good agreement. It can be shown that the change on the (γ → α)-transformation kinetic driven by the inhomogeneous distribution of the chemical contents causes a strong influence on the weld residual stresses within the volume of the weld pool, which could promote crack propagation within the solidified weld pool by use of high-alloyed filler materials. Furthermore, a significant influence on the development of the transient welding distortion is visible. This influence should be respected during numerically calculation of welding distortion in case of multi-pass welding using interpass temperatures and high-alloyed filler materials. KW - Welding residual stresses KW - FEA KW - Welding simulation KW - Dissimilar welding KW - Transformable steels PY - 2017 DO - https://doi.org/10.1016/j.jcsr.2016.08.020 SN - 0143-974X SN - 1873-5983 VL - 128 SP - 193 EP - 200 PB - Elsevier Ltd. AN - OPUS4-37276 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rosemann, Paul A1 - Müller, C. A1 - Baumann, O. A1 - Modersohn, W. A1 - Halle, T. T1 - Influence of the post-weld surface treatment on the corrosion resistance of the duplex stainless steel 1.4062 JF - IOP Conf. Series: Materials Science and Engineering N2 - The duplex stainless steel 1.4062 (X2CrNiN22-2) is used as alternative material to austenitic stainless steels in the construction industry. The corrosion resistance of welded seams is influenced by the base material, the weld filler material, the welding process and also by the final surface treatment. The scale layer next to the weld seam can be removed by grinding, pickling, electro-polished or blasting depending on the application and the requested corrosion resistance. Blasted surfaces are often used in industrial practice due to the easier and cheaper manufacturing process compared to pickled or electro-polished surfaces. Furthermore blasting with corundum-grain is more effective than blasting with glass-beads which also lower the process costs. In recent years, stainless steel surfaces showed an unusually high susceptibility to pitting corrosion after grinding with corundum. For this reason, it is now also questioned critically whether the corrosion resistance is influenced by the applied blasting agent. This question was specifically investigated by comparing grinded, pickled, corundum-grain- and glass-bead-blasted welding seams. Results of the SEM analyses of the blasting agents and the blasted surfaces will be presented and correlated with the different performed corrosion tests (potential measurement, KorroPad-test and pitting potential) on welding seams with different surface treatments. T2 - 19th Chemnitz Seminar on Materials Engineering – 19. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 16.03.2017 KW - Corrosion resistance KW - Welding KW - Duplex stainless steels KW - Pitting corrosion KW - Surface treatment PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395374 DO - https://doi.org/10.1088/1757-899X/181/1/012019 SN - 1757-899X SN - 1757-8981 VL - 181 IS - Conference 1 SP - Article UNSP 012019, 1 EP - 9 PB - IOP Publishing CY - Bristol, UK AN - OPUS4-39537 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wachtendorf, Volker A1 - Kalbe, Ute A1 - Krüger, O. A1 - Bandow, Nicole ED - Brown, R. ED - Gedde, U.W. ED - Hedenqvist, M.S. T1 - Influence of weathering on the leaching behaviour of zinc and PAH from synthetic sports surfaces JF - Polymer Testing N2 - Synthetic materials used for outdoor sports grounds consist of a mix of inorganic, organic and polymeric compounds that show ageing due to weathering and a complex leaching behaviour by percolation of rainwater, which can limit its lifetime. Additionally, weathering exposure induces degradation processes in the polymers, which leads to the formation of new surfaces allowing water to access additional reservoirs of leachable compounds. A laboratory test comprising artificial weathering, ozonisation and subsequent leaching was developed to investigate this behaviour in a reproducible and controllable way. The experiments showed a general decline of Zn, polycyclic aromatic hydrocarbons (PAH) and total organic carbon (TOC) concentrations after an initial increase. Within this general trend, the course of concentration over exposure duration is very specific for individual sample materials and the analyte under investigation. The results indicate that weathering and degradation behaviour cannot be predicted from initial material conditions. Thus, weathering experiments are recommended to fill this gap of knowledge. KW - Athletic tracks KW - Artificial turf KW - Ageing KW - Artificial weathering KW - Polymer degradation KW - Rubber granules KW - Leaching KW - Contamination PY - 2017 DO - https://doi.org/10.1016/j.polymertesting.2017.09.021 SN - 0142-9418 SN - 1873-2348 VL - 63 IS - October SP - 621 EP - 631 PB - Elsevier Ltd. CY - Amsterdam, The Netherlands AN - OPUS4-42205 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schmidt, Wolfram A1 - Brouwers, H.J.H. A1 - Kühne, Hans-Carsten A1 - Meng, Birgit T1 - Interactions of polysaccharide stabilising agents with early cement hydration without and in the presence of superplasticizers JF - Construction and Building Materials N2 - Polysaccharides are incorporated into cement based Systems in order to modify the rheological properties. Typically, cellulose ethers, sphingan gums, guar gum or starch ethers are applied. Depending upon their chemistry, molecular architecture, and adsorption tendency, polysaccharides interact differently with the entire cementitious system. Some stabilising agents like diutan gum mainly affect the cementitious paste; other stabilising agents like starch tend to interact with the sand fraction and even with the coarse aggregates. Cellulose and guar gum shows more diverse performances. Typically stabilising admixtures like polysaccharides are used, when sophisticated rheological properties are adjusted. Therefore, polysaccharides are often used in combination with superplasticisers, which are added to reduce the yield stress of concrete. This can cause interactions, particularly when the stabilising Agent shows a strong tendency to adsorb on particle surfaces. Adsorptive stabilising agents may reduce the amount of adsorbed superplasticisers, thus affecting both viscosity and yield stress, while non-adsorptive stabilising agents mainly affect the plastic viscosity independently of the superplasticiser. Due to the strong influence of superplasticisers on the yield stress, influences of the stabilising agent on the yield stress retreat into the background, so that their major effect is an increase of the plastic viscosity. The paper provides a comprehensive overview of how different polysaccharide superplasticisers affect cementitious flowable systems and points out the challenges of the combined use of polysaccharides and superplasticisers. Based on rheometric experiments and observations of the hydration process, time dependent effects on the workability as well as of the hydration of cement are presented and discussed. KW - Concrete KW - Polysaccharides KW - Rheology KW - Stabilising agents KW - Starch KW - Sphingan PY - 2017 DO - https://doi.org/10.1016/j.conbuildmat.2016.11.022 SN - 0950-0618 SN - 1879-0526 VL - 139 SP - 584 EP - 593 PB - Elsevier AN - OPUS4-40597 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wolf, Marcus A1 - Afanasiev, Roman A1 - Böllinghaus, Thomas A1 - Pfennig, A. T1 - Investigation of Corrosion Fatigue of Duplex Steel X2CrNiMoN22-5 3 Exposed to a Geothermal Environment under Different Electrochemical Conditions and Load Types JF - Energy Procedia N2 - Corrosion fatigue (CF) of duplex stainless steel (DSS) X2CrNiMoN22-5-3 was investigated in in-situ geothermal conditions of the Northern German Basin (NGB). The influence of the load type on CF behavior of the alloy was examined by applying push/pull and rotating bending cyclic load to failure. The hour-glass shaped specimens with both polished and precisely turned surface finish were tested in corrosion chambers allowing for the permanent circulation of Northern German Basin electrolyte heated to 369 K. Additionally, the influence of a protective cathodic potential on the CF life expectancy was investigated by employing a potentiostat. The rotating bending cyclic load led to a higher CF life expectancy, which decreased with increasing duration of the experiment due to a higher deterioration rate of the material. The application of a cathodic potential caused a significant increase of the CF lifespan from 4.7 x 105 (open-circuit potential (OCP)) to 107 cycles (preset threshold cycle number) for the potential range from USHE = – 450 to – 900 mV. Microstructural analysis of the CF damage revealed horizontal grain attack within corrosion pit cavities, multiple fatigue cracks and preferable deterioration of the austenitic phase. T2 - 13th International Conference on Greenhouse Gas Control Technologies, GHGT-13 CY - Lausanne, Switzerland DA - 14.11.2016 KW - Different load cases KW - Corrosion fatigue KW - DSS KW - Geothermal environment KW - Different electrochemical conditions PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-439231 DO - https://doi.org/10.1016/j.egypro.2017.03.1657 SN - 1876-6102 VL - 114 SP - 5337 EP - 5345 PB - Elsevier Science AN - OPUS4-43923 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bakir, Nasim A1 - Gumenyuk, Andrey A1 - Rethmeier, Michael T1 - Investigation of solidification cracking susceptibility during laser beam welding using an in-situ observation technique JF - Science and Technology of Welding and Joining N2 - Using the novel optical measurement technique together with the optical flow algorithm, a twodimensional deformation analysis during welding has been conducted. This technique provides for the first time a measurement of the strain field locally in the immediate vicinity of the assumed solidification front. The described procedure of the opticalmeasurement allows to determine the real martial-dependent values of critical strain and strain rate characterising transition to the hot cracking during laser welding processes. The local critical strain that obtained in the assumed solidification showed that the local critical strain decreases as the strain rate increases. Moreover, this phenomenon has also been shown with results from the CTW-test, since the global strain decreases with an increase in the external strain rate. KW - Novel optical measurement KW - Local critical strain KW - Solidification cracking KW - Laser beam Welding PY - 2017 DO - https://doi.org/10.1080/13621718.2017.1367550 SN - 1362-1718 SP - 1 EP - 7 PB - Taylor & Francis AN - OPUS4-42918 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pavlovic, Mato A1 - Zoëga, Andreas A1 - Kurz, J. H. A1 - Zanotelli, Christina T1 - Investigations to introduce the probability of detection method for ultrasonic inspection of hollow axles at Deutsche Bahn JF - Procedia Structural Integrity N2 - The vast experience with the automated, ultrasonic system for the inspection of hollow railway axles used by Deutsche Bahn shows that much smaller flaws are detectable than required. This results in a number of false calls. False calls lead to unnecessary demounting and disassembling of wheelsets, which generates unnecessary additional costs. In order to adjust the sensitivity of the inspection system to reduce the number of false calls without compromising safety, the capability of the system to detect cracks needs to be comprehensively established. This capability can be quantified by using probability of detection (POD) curves for the system. The multi-parameter POD model makes it possible to include several factors that influence the crack detection in the analysis. The analysis presented in this paper shows that crack position, orientation, depth extension, and shape as well as the geometry of the axle all have influence on the ultrasonic response amplitude. For future work, calculation of the POD using multi-parameter POD model with these parameters is planned. T2 - ESIS TC24 Workshop "Integrity of Railway Structures" CY - Leoben, Austria DA - 24.10.2016 KW - Crack KW - Reliability KW - POD KW - Axle KW - Ultrasonic PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-415201 DO - https://doi.org/10.1016/j.prostr.2017.07.002 SN - 2452-3216 VL - 4 SP - 79 EP - 86 PB - Elsevier, B.V. AN - OPUS4-41520 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lichtenstein, D. A1 - Ebmeyer, J. A1 - Meyer, T. A1 - Behr, A.-C. A1 - Kästner, Claudia A1 - Böhmert, L. A1 - Juling, J. A1 - Niemann, B. A1 - Fahrenson, C. A1 - Selve, S. A1 - Thünemann, Andreas A1 - Meijer, J. A1 - Estrela-Lopis, I. A1 - Bräuning, A. A1 - Lampen, A. T1 - It takes more than a coating to get nanoparticles through the intestinal barrier in vitro JF - European Journal of Pharmaceutics and Biopharmaceutics N2 - Size and shape are crucial parameters which have impact on the potential of nanoparticles to penetrate cell membranes and epithelial barriers. Current research in nanotoxicology additionally focuses on particle coating. To distinguish between core- and coating-related effects in nanoparticle uptake and translocation, two nanoparticles equal in size, coating and charge but different in core material were investigated. Silver and iron oxide nanoparticles coated with poly(acrylic acid) were chosen and extensively characterized by small-angle x-ray scattering, nanoparticle tracing analysis and transmission electron microscopy (TEM). Uptake and transport were studied in the intestinal Caco-2 model in a Transwell System with subsequent elemental analysis. TEM and ion beam microscopy were conducted for particle visualization. Although equal in size, charge and coating, the behavior of the two particles in Caco-2 cells was different: while the internalized amount was comparable, only iron oxide nanoparticles additionally passed the epithelium. Our findings suggest that the coating material influenced only the uptake of the nanoparticles whereas the translocation was determined by the core material. Knowledge about the different roles of the particle coating and core materials in crossing biological barriers will facilitate toxicological risk assessment of nanoparticles and contribute to the optimization of pharmacokinetic properties of nano-scaled pharmaceuticals. KW - Silver KW - Nanoparticle KW - Polymer KW - Polyacrylic acid PY - 2017 DO - https://doi.org/10.1016/j.ejpb.2016.12.004 SN - 0939-6411 SN - 1873-3441 VL - 118 SP - 21 EP - 29 PB - Elsevier AN - OPUS4-41170 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Günster, Jens T1 - Keramische Prozesstechnik: InTeRview mit Prof. Dr. Jens Günster JF - InTeR Zeitschrift zum Innovations- und Technikrecht N2 - Im Rahmen unserer turnusmäßig erscheinenden Rubrik InTeRdisziplinär stellt sich heute Prof. Dr. Jens Günster, Leiter des Fachbereichs "Keramische Prozesstechnik und Biowerkstoffe" bei der Bundesanstalt für Materialforschung und-prüfung, den FRagen der InTeR. KW - Innovationsrecht KW - Technikrecht KW - Additive Fertigung KW - Keramik PY - 2017 SN - 2195-5743 VL - 5 SP - 122 EP - 124 PB - dfv Mediengruppe CY - Frankfurt am Main AN - OPUS4-42015 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulla, Hannes A1 - Greiser, Sebastian A1 - Benemann, Sigrid A1 - Rademann, K. A1 - Emmerling, Franziska T1 - Knowing When To Stop-Trapping Metastable Polymorphs in Mechanochemical Reactions JF - Crystal Growth and Design N2 - The cocrystal formation of pyrazinamide (PZA) with malonic acid (MA) was studied in situ. The mechanochemical reaction proceeds via conversion of a crystalline intermediate (PZA:MA II) into the thermodynamically more stable form (PZA:MA I) upon further grinding. The information derived from in situ powder X-ray diffraction (PXRD) enabled the isolation of this new metastable polymorph. On the basis of the PXRD data, the crystal structure of the 1:1 cocrystal PZA:MA II was solved. The polymorphs were further characterized and compared by Raman spectroscopy, solid-state NMR spectroscopy, differential thermal analysis/thermogravimetric analysis, and scanning electron microscopy. Our study demonstrates how monitoring mechanochemical reactions by in situ PXRD can direct the discovery and isolation of even short-lived intermediates not yet accessed by conventional methods. KW - Mechanochemistry KW - Polymorphs KW - Metastable KW - In situ PXRD KW - Cocrystal KW - Pyrazinamide PY - 2017 DO - https://doi.org/10.1021/acs.cgd.6b01572 SN - 1528-7483 SN - 1528-7505 VL - 17 IS - 3 SP - 1190 EP - 1196 AN - OPUS4-39420 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Leonhard, H. T1 - Korrosionsschutz bekennt Farbe - Schnelltest auf Korrosionsgefahr bei nicht rostenden Stählen JF - Chemie Technik N2 - In Chemieanlagen ist die Passivschicht von Rohrsystemen und Behältern aus nichtrostendem Stahl nicht nur durch den rauen Produktionsalltag gefährdet. Auch im Neuzustand können Schäden entstehen, bspw. durch Schleifvorgänge oder eine unvollständige Entfernung von Anlauffarben nach dem Schweißen. TÜV SÜD Chemie Service beteiligte sich an der Prüfung eines von der Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelten Korrosionsschnelltests. KorroPads liefern in nur 15 Minuten eine valide Aussage zum Zustand der Passivschicht auf den Werkstoffoberflächen. KW - Nichtrostender Stahl KW - Korrosionsschnelltest KW - KorroPad KW - Passivschicht PY - 2017 SN - 0340-9961 VL - 46 IS - 11 SP - 46 EP - 48 PB - Hüthig GmbH CY - Heidelberg AN - OPUS4-43120 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Heitz, J. A1 - Plamadeala, C. A1 - Muck, M. A1 - Habidzadeh, H. A1 - Baumgartner, W. A1 - Weth, A. A1 - Steinwender, C. A1 - Blessberger, H. A1 - Kellermair, J. A1 - Kirner, Sabrina V. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Guntner, A. S. A1 - Hassel, A. W. T1 - Laser-induced microstructures on Ti substrates for reduced cell adhesion JF - Journal für Kardiologie - Austrian Journal of Cardiology N2 - The abstract summarizes the poster presented at the "Kardiologie im Zentrum - Fortbildung der Klinik für Kardiologie und Intensivmedizin Kepler Universitätsklinikum Linz", held between October 20th and 31st in Linz, Austria. The poster has been awarded the 2nd place of the "Best Poster Award". T2 - Kardiologie im Zentrum - Fortbildung der Klinik für Kardiologie und Intensivmedizin Kepler Universitätsklinikum Linz CY - Linz, Austria DA - 20.10.2017 KW - Femtosecond laser processing KW - Titanium alloy KW - Cell adhesion KW - Pacemaker PY - 2017 UR - http://www.kup.at/kup/pdf/14098.pdf SN - 1024-0098 VL - 24 IS - 11-12 SP - 292 EP - 292 PB - Krause & Pachernegg GmbH CY - Gablitz, Austria AN - OPUS4-43160 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Laser-induced periodic surface structures on zinc oxide crystals upon two-colour femtosecond double-pulse irradiation JF - Physica Scripta N2 - In order to study the temporally distributed energy deposition in the formation of laser-induced periodic surface structures (LIPSS) on single-crystalline zinc oxide (ZnO), two-colour double-fs-pulse experiments were performed. Parallel or cross-polarised double-pulse sequences at 400 and 800 nm wavelength were generated by a Mach–Zehnder interferometer, exhibiting inter-pulse delays up to a few picoseconds between the sub-ablation 50-fs-pulses. Twenty two-colour double-pulse sequences were collinearly focused by a spherical mirror to the sample surface. The resulting LIPSS periods and areas were analysed by scanning electron microscopy. The delay-dependence of these LIPSS characteristics shows a dissimilar behaviour when compared to the semiconductor silicon, the dielectric fused silica, or the metal titanium. A wavelength-dependent plasmonic mechanism is proposed to explain the delay-dependence of the LIPSS on ZnO when considering multi-photon excitation processes. Our results support the involvement of nonlinear processes for temporally overlapping pulses. These experiments extend previous two-colour studies on the indirect semiconductor silicon towards the direct wide band-gap semiconductor ZnO and further manifest the relevance of the ultrafast energy deposition for LIPSS formation. KW - Laser-induced periodic surface structures, LIPSS KW - Laser ablation KW - Surface plasmon polariton PY - 2017 DO - https://doi.org/10.1088/1402-4896/aa5578 SN - 1402-4896 SN - 0031-8949 VL - 92 IS - 3 SP - Article 034003, 1 EP - 7 PB - IOP CY - Bristol, UK AN - OPUS4-39082 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn A1 - Höhm, S. A1 - Kirner, Sabrina V. A1 - Rosenfeld, A. A1 - Krüger, Jörg T1 - Laser-induced periodic surface structures — a scientific evergreen JF - IEEE Journal of Selected Topics in Quantum Electronics N2 - Laser-induced periodic surface structures (LIPSS, ripples) are a universal phenomenon and can be generated on almost any material upon irradiation with linearly polarized radiation. With the availability of ultrashort laser pulses, LIPSS have gained an increasing attraction during the past decade, since these structures can be generated in a simple single-step process, which allows a surface nanostructuring for tailoring optical, mechanical, and chemical surface properties. In this study, the current state in the field of LIPSS is reviewed. Their formation mechanisms are analyzed in ultrafast time-resolved scattering, diffraction, and polarization constrained double-pulse experiments. These experiments allow us to address the question whether the LIPSS are seeded via ultrafast energy deposition mechanisms acting during the absorption of optical radiation or via self-organization after the irradiation process. Relevant control parameters of LIPSS are identified, and technological applications featuring surface functionalization in the fields of optics, fluidics, medicine, and tribology are discussed. KW - Laser ablation KW - Nanostructures KW - Surface functionalization KW - Surface texture KW - Laser-induced periodic surface structures (LIPSS) PY - 2017 DO - https://doi.org/10.1109/JSTQE.2016.2614183 SN - 1077-260X SN - 1558-4542 VL - 23 IS - 3 SP - 9000615 PB - IEEE AN - OPUS4-38633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lüchtenborg, Jörg A1 - Mühler, T. A1 - Léonard, Fabien A1 - Günster, Jens T1 - Laser-induced slip casting (LIS) – a new additive manufacturing process for dense ceramics demonstrated with Si3N4 JF - Journal of Ceramic Science and Technology N2 - Up to now, there exists a lack of methods for the additive manufacturing of voluminous ceramic parts with properties comparable to those of conventionally manufactured ones. A high density after sintering is needed to reach the superior properties of ceramic materials. We have developed a new additive manufacturing method, Laser-Induced Slip casting (LIS), to generate ceramic green bodies with high particle packing density and with virtually no restriction in the particle size of the feedstock, especially in terms of small particles. This is achieved by laser-induced local drying of slurries, with the process resembling many features of the well-established stereolithography, but without the excessive use of polymeric material. Thus, unlike the stereolithography process, the resulting green bodies can be processed like traditionally produced ceramic parts. This method allows large and dense additive-manufactured parts to be obtained from conventional water-based ceramic slurries. As an example, we will demonstrate the application of this novel technique with Si3N4. KW - Additive manufacturing KW - Ceramics PY - 2017 DO - https://doi.org/10.4416/JCST2017-00091 SN - 2190-9385 VL - 8 IS - 4 SP - 531 EP - 540 PB - Göller Verlag CY - Baden-Baden AN - OPUS4-43738 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rethmeier, Michael A1 - Finkbeiner, M. T1 - Licht ist grüner als Strom JF - Laser Community N2 - Laserschweißen gegen Widerstandspunktschweißen: Die Die Entscheidung fällt am Flansch. Beide Verfahren sind sehr schnell und hoch automatisierbar. KW - Laserschweißen KW - Widerstandspunktschweißen PY - 2017 VL - 24 SP - 6 EP - 6 AN - OPUS4-40413 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zocca, Andrea A1 - Lima, Pedro A1 - Günster, Jens T1 - LSD-based 3D printing of alumina ceramics JF - Journal of Ceramic Science and Technology N2 - An improved method of powder 3D printing leading to dense ceramic parts is presented. The application of powder-based binder jetting 3D printing technologies to technical ceramics is generally limited by the low packing density of the powder and by the need to use a flowable powder. With layer-wise slurry deposition, it is, however, possible to deposit powder beds with high particle packing and furthermore using submicron powders. This method was combined with the binder jetting technology to develop a novel process, named LSD-print. By means of LSD-print, a submicron Al2O3 powder could be processed to produce samples with a density comparable with that of standard pressed samples, both in the green state and after sintering. KW - Additive manufacturing KW - Layer-wise slurry deposition KW - Dense alumina KW - 3D printing PY - 2017 DO - https://doi.org/10.4416/JCST2016-00103 SN - 2190-9385 VL - 8 IS - 1, SI SP - 141 EP - 147 PB - Göller Verlag GmbH CY - Baden Baden AN - OPUS4-39672 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Batzdorf, Lisa A1 - Zientek, Nicolai A1 - Rump, Doreen A1 - Fischer, Franziska A1 - Maiwald, Michael A1 - Emmerling, Franziska T1 - Make and break - Facile synthesis of cocrystals and comprehensive dissolution studies JF - Journal of Molecular Structure N2 - Mechanochemistry is increasingly used as a ‘green alternative’ for synthesizing various materials including pharmaceutical cocrystals. Herein, we present the mechanochemical synthesis of three new cocrystals containing the API carbamazepine (cocrystals CBZ:Indometacin 1:1, CBZ:Benzamide 1:1, and CBZ:Nifedipine 1:1). The mechanochemical reaction was investigated in situ documenting a fast and complete reaction within one minute. Online NMR spectroscopy proved the direct influence of the dissolution behaviour of the coformers to the dissolution behaviour of the API carbamazepine. The dissolution behaviour of the organic cocrystals is compared to the behaviour of the pure drug indicating a general applicability of this approach for detailed cocrystal dissolution studies. KW - Cocrystals KW - Carbamazepine KW - Mechanochemistry KW - Powder diffraction KW - Online NMR spectroscopy PY - 2017 DO - https://doi.org/10.1016/j.molstruc.2016.11.063 SN - 0022-2860 SN - 1872-8014 VL - 1133 SP - 18 EP - 23 AN - OPUS4-38664 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Scheuerlein, C. A1 - Uhlemann, Patrick A1 - Finn, Monika A1 - Lackner, F. A1 - Savary, F. T1 - Mechanical properties of the HL-LHC 11 T Nb3Sn magnet constituent materials JF - IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY N2 - A test campaign was launched to determine the mechanical properties of the High Luminosity-Large HadronCollider (HL-LHC) 11 T Nb3Sn magnet components. The results can be used to accurately represent the mechanical properties in finite elementmodels that predict the stress and strain distribution in these magnets. Particular attention is paid to anisotropic mechanical behavior of the different magnet materials. Static and dynamic test methods have been applied for determining elastic materials’ behavior, and highly accurate Young’s moduli are obtained with the nondestructive dynamic methods resonance and impulse excitation at ambient temperature and during in situ heat cycles. KW - Superconducting magnets KW - Young’s modulus KW - Resonance testing KW - Stress-strain behavior PY - 2017 DO - https://doi.org/10.1109/TASC.2016.2638046 SN - 1051-8223 SN - 1558-2515 VL - 27 IS - 4 SP - 1 EP - 7 PB - IEEE AN - OPUS4-39219 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schulz, K. A1 - Schmack, R. A1 - Klemm, H. W. A1 - Kabelitz, Anke A1 - Schmidt, T. A1 - Emmerling, Franziska A1 - Kraehnert, R. T1 - Mechanism and kinetics of hematite crystallization in air: Linking bulk and surface models via mesoporous films with defined nanostructure JF - Chemistry of Materials N2 - Iron can form numerous oxides, hydroxides, and oxide−hydroxides. Despite their relevance, many of the transformation processes between these phases are still poorly understood. In particular the crystallization of quasi-amorphous hydroxides and oxide−hydroxides is difficult to assess, since typical diffraction and scattering methods provide only sampleaveraged information about the crystallized phases. We report a new approach for the investigation of the crystallization of oxide−hydroxides. The approach relies on model-type films that comprise a defined homogeneous nanostructure. The nanostructure allows quantitative linking of Information obtained by bulk-averaging diffraction techniques (XRD, SAXS) with locally resolved information, i.e., Domain sizes (SEM, TEM, LEEM) and phase composition (SAED). Using time-resolved imaging and diffraction we deduce mechanism and kinetics for the crystallization of ferrihydrite into hematite. Hematite forms via nucleation of hematite domains and subsequent Domain growth that terminates only upon complete transformation. A Johnson−Mehl−Avrami−Kolmogorov model describes the kinetics over a wide temperature range. The derived understanding enables the first synthesis of ferrihydrite films with ordered mesoporosity and quantitative control over the films’ hematite and ferrihydrite content. KW - Iron oxide KW - Crystallization KW - Mesoporous films KW - Nanostructure PY - 2017 DO - https://doi.org/10.1021/acs.chemmater.6b05185 SN - 0897-4756 SN - 1520-5002 VL - 29 IS - 4 SP - 1724 EP - 1734 AN - OPUS4-39690 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Haferkamp, Sebastian A1 - Fischer, Franziska A1 - Kraus, Werner A1 - Emmerling, Franziska T1 - Mechanochemical Knoevenagel condensation investigated in situ JF - Beilstein Journal of organic chemistry N2 - The mechanochemical Knoevenagel condensation of malononitrile with p-nitrobenzaldehyde was studied in situ using a tandem approach. X-ray diffraction and Raman spectroscopy were combined to yield time-resolved information on the milling process. Under solvent-free conditions, the reaction leads to a quantitative conversion to p-nitrobenzylidenemalononitrile within 50 minutes. The in situ data indicate that the process is fast and proceeds under a direct conversion. After stopping the milling process, the reaction continues until complete conversion. The continuous and the stopped milling process both result in crystalline products suitable for single crystal X-ray diffraction. KW - Mechanochemistry KW - Ball milling KW - C–C coupling KW - In situ KW - Knoevenagel condensation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-425388 DO - https://doi.org/10.3762/bjoc.13.197 VL - 13 SP - 2010 EP - 2014 PB - Beilstein-Institut AN - OPUS4-42538 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Erning, Johann Wilhelm T1 - Metallene Werkstoffe im Trinkwasser – Typische Schadensfälle JF - GG Nachrichten N2 - Typische Schadenbilder werden theoretische erläutert und mit Beispielen aus der Praxis nachvollzogen. KW - Trinkwasser KW - Korrosion KW - Kupferlegierungen PY - 2017 SN - 2366-3960 VL - 11 IS - November SP - 5 EP - 7 PB - Gesundheitstechnische Gesellschaft CY - Berlin AN - OPUS4-42662 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Poyet, S. A1 - Dridi, W. A1 - L'Hostis, V. A1 - Meinel, Dietmar T1 - Microstructure and diffusion coefficient of an old corrosion product layer and impact on steel rebar corrosion in carbonated concrete JF - Corrosion Science N2 - Corrosion is the major degradation pathway affecting reinforced concrete structures. In the long-term, the rust layer might become thick and slow down the diffusion of oxygen from the atmosphere to the steel. With this in mind, the mineralogy, microstructure and diffusion properties of an old and thick corrosion product layer were investigated. Despite the presence of macropores, the gas diffusion coefficient was found to be low. The impact of the layer on the oxygen diffusion was evaluated using Fick’s law. The results showed that the layer could reduce the flux of oxygen only in a specific configuration. KW - Steel reinforced concrete KW - Rust KW - X-ray computed tomography KW - Micro-CT PY - 2017 DO - https://doi.org/10.1016/j.corsci.2017.06.002 VL - 2017 IS - 125 SP - 48 EP - 58 PB - Elsevier B.V. CY - Radarweg 29, 1043 NX Amsterdam, The Netherlands AN - OPUS4-41784 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, S. G. A1 - Vleugels, J. A1 - Mohrbacher, H. A1 - Woydt, Mathias T1 - Microstructure and tribological performance of NbC-Ni cermets modified by VC and Mo2C JF - International Journal of Refractory Metals & Hard Materials N2 - The current study reports on the influence of the Addition of 5–15 vol% VC or/and Mo2C carbide on the microstructure and mechanical properties of nickel bonded NbC cermets, which are compared to cobalt bonded NbC cermets. The NbC, Ni and secondary carbides powder mixtures were liquid phase sintered for 1 h at 1420 °C in vacuum. The fully densified cermets are composed of a cubic NbC grains matrix and an evenly distributed fcc Ni binder. NbC grain growth was significantly inhibited and a homogeneous NbC grain size distribution was obtained in the cermets with VC/Mo2C additions. The mechanical properties of the NbC-Ni matrix cermets are strongly dependent on the carbide and Ni binder content and are directly compared to their NbC-Co equivalents. The liquid phase sintered NbC-12 vol% Ni cermet had a modest Vickers hardness (HV30) of 1077 ± 22 kg/mm2 and an indentation toughness of 9.1 ± 0.5 MPa·m1/2. With the addition of 10–15 vol% VC, the hardness increased to 1359 ± 15 kg/mm2, whereas the toughness increased to 11.3 ± 0.1 MPa·m1/2. Addition of 5 and 10 vol% Mo2C into a NbC-12 vol% Ni mixtures generated the same values in HV30 and KIC when compared to VC additions. A maximum flexural strength of 1899 ± 77 MPa was obtained in the cermet with 20 vol% Ni binder and 4 vol% VC+4 vol% Mo2C addition, exhibiting a high fracture toughness of 15.0 ± 0.5 MPa·m1/2, but associated with a loss in hardness due to the high Ni content. The dry sliding wear behaviour was established at room temperature and 400 °C from 0.1 to 10 m/s. KW - Cermet KW - Liquid phase sintering KW - Grain growth KW - Wear KW - Niobium carbide PY - 2017 DO - https://doi.org/10.1016/j.ijrmhm.2017.03.012 SN - 0263-4368 VL - 66 SP - 188 EP - 197 AN - OPUS4-40505 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Lange, Axel A1 - Bruno, Giovanni T1 - Microstructure Characterization of Ceramics via 2D and 3D X-Ray Refraction Techniques JF - Journal of the European Ceramic Society N2 - 3D imaging techniques are very fashionable nowadays, and allow enormous progress in understanding ceramic microstructure, its evolution, and its link to mechanical, thermal, and transport properties. In this feature article, we report the use of a powerful, yet not so wide-spread, set of X-ray techniques based on refraction effects. X-ray refraction allows determining internal specific surface (surface per unit volume) in a non-destructive fashion, position and orientation sensitive, and with a nanometric detectability. While the techniques are limited by the X-ray absorption of the material under investigation, we demonstrate showcases of ceramics and composite materials, where understanding of process parameter influence or simply of microstructural parameters could be achieved in a way unrivalled even by high-resolution techniques such as electron microscopy or computed tomography. KW - X-ray refraction KW - Porosity KW - Specific surface KW - Crack detection KW - Composites PY - 2017 DO - https://doi.org/10.1016/j.jeurceramsoc.2016.12.031 SN - 0955-2219 SN - 1873-619X VL - 37 IS - 5 SP - 1879 EP - 1889 PB - Elsevier CY - Amsterdam AN - OPUS4-39094 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hermens, U. A1 - Kirner, Sabrina A1 - Emonts, C. A1 - Comanns, P. A1 - Skoulas, E. A1 - Mimidis, A. A1 - Mescheder, H. A1 - Winands, K. A1 - Krüger, Jörg A1 - Stratakis, E. A1 - Bonse, Jörn T1 - Mimicking lizard-like surface structures upon ultrashort laser pulse irradiation of inorganic materials JF - Applied Surface Science N2 - Inorganic materials, such as steel, were functionalized by ultrashort laser pulse irradiation (fs- to ps-range) to modify the surface’s wetting behavior. The laser processing was performed by scanning the laser beam across the surface of initially polished flat sample material. A systematic experimental study of the laser processing parameters (peak fluence, scan velocity, line overlap) allowed the identification of different regimes associated with characteristic surface morphologies (laser-induced periodic surface structures, grooves, spikes, etc.). Analyses of the surface using optical as well as scanning electron microscopy revealed morphologies providing the optimum similarity to the natural skin of lizards. For mimicking skin structures of moisture-harvesting lizards towards an optimization of the surface wetting behavior, additionally a two-step laser processing strategy was established for realizing hierarchical microstructures. In this approach, micrometer-scaled capillaries (step 1) were superimposed by a laser-generated regular array of small dimples (step 2). Optical focus variation imaging measurements finally disclosed the three dimensional topography of the laser processed surfaces derived from lizard skin structures. The functionality of these surfaces was analyzed in view of wetting properties. KW - Femtosecond laser ablation KW - Laser-induced periodic surface structures KW - Lizard KW - Surface wetting KW - Fluid transport KW - Steel PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S0169433216328306 DO - https://doi.org/10.1016/j.apsusc.2016.12.112 SN - 0169-4332 SN - 1873-5584 VL - 418 IS - Part B SP - 499 EP - 507 PB - Elsevier, North-Holland CY - Amsterdam AN - OPUS4-40509 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dutto, Paola A1 - Stickle, M. M. A1 - Pastor, M. A1 - Manzanal, D. A1 - Yague, A. A1 - Tayyebi, S. A1 - Lin, C. A1 - Elizalde, M. D. ED - Cervera, Miguel T1 - Modelling of fluidised geomaterials: the case of the Aberfan and the Gypsum tailings impoundment flowslides JF - Materials N2 - The choice of a pure cohesive or a pure frictional viscoplastic model to represent the rheological behaviour of a flowslide is of paramount importance in order to obtain accurate results for real cases. The principal Goal of the present work is to clarify the influence of the type of viscous model—pure cohesive versus pure frictional—with the numerical reproduction of two different real flowslides that occurred in 1966: the Aberfan flowslide and the Gypsum tailings impoundment flowslide. In the present work, a depth-integrated model based on the v-pw Biot–Zienkiewicz formulation, enhanced with a diffusion-like equation to account for the pore pressure Evolution within the soil mass, is applied to both 1966 cases. For the Aberfan flowslide, a frictional viscous model based on Perzyna viscoplasticity is considered, while a pure cohesive viscous model (Bingham model) is considered for the case of the Gypsum flowslide. The numerical approach followed is the SPH method, which has been enriched by adding a 1D finite difference grid to each SPH node in order to improve the description of the pore water evolution in the propagating mixture. The results obtained by the performed simulations are in agreement with the documentation obtained through the UK National Archive (Aberfan flowslide) and the International Commission of large Dams (Gypsum flowslide). KW - Aberfan flowslide KW - SPH KW - Landslide propagation modelling KW - Perzyna viscoplasticity PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-410493 DO - https://doi.org/10.3390/ma10050562 SN - 1996-1944 VL - 10 IS - 5 SP - 562, 1 EP - 562, 21 AN - OPUS4-41049 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tuma, Dirk A1 - Kumbhar, V. S. A1 - Lee, Y. R. A1 - Ra, C. S. A1 - Min, B.-K. A1 - Shim, J.-J. T1 - Modified chemical synthesis of MnS nanoclusters on nickel foam for high performance all-solid-state asymmetric supercapacitors JF - RSC Advances N2 - Novel MnS nanoclusters were synthesized on nickel foam (NF) using a successive ionic layer adsorption and reaction (SILAR) method. MnS nanoclusters with different sizes were obtained by varying the number of deposition cycles. The crystal structure, chemical composition, and surface microstructure of the electrodes were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field Emission scanning electron microscopy, and high-resolution transmission electron microscopy. The electrochemical behavior of the MnS nanoclusters was examined by cyclic voltammetry, galvanostatic charge–discharge, cycling test, and electrochemical impedance spectroscopy. The MnS nanoclusters prepared with 90 SILAR cycles showed the best supercapacitance in a 6 M KOH aqueous electrolyte with a specific capacitance of 828 F/g at a scan rate of 5 mV/s and cycling stability of 85.2 % after 5000 charge–discharge cycles. Moreover, an asymmetric supercapacitor (ASC) was assembled with the as-prepared MnS electrode on NF as the positive electrode, hydrothermally prepared reduced graphene oxide (rGO) on NF as the negative electrode, and PVA–KOH gel as the electrolyte. The MnS@NF//rGO@NF ASC showed excellent electrochemical performance with maximum energy and power densities of 34.1 Wh/kg and 12.8 kW/kg, respectively. The ASC also showed a capacitive retention of 86.5 % after 2000 charge–discharge cycles, highlighting its practical application for energy storage. KW - Nanocluster KW - Electrochemical behavior KW - Asymmetric supercapacitor KW - Graphene oxide PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-403147 DO - https://doi.org/10.1039/c7ra00772h SN - 2046-2069 VL - 7 IS - 27 SP - 16348 EP - 16359 PB - The Royal Society of Chemistry CY - London AN - OPUS4-40314 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Konnertz, Nora A1 - Ding, Yi A1 - Harrison, W.J. A1 - Budd, P.M. A1 - Schönhals, Andreas A1 - Böhning, Martin T1 - Molecular mobility and gas transport properties of nanocomposites based on PIM-1 and polyhedral oligomeric phenethyl-silsesquioxanes (POSS) JF - Journal of Membrane Science N2 - Polymers with intrinsic microporosity (PIMs) are of great interest in the field of gas separation membranes. Already the first synthesized PIM-1 shows extraordinary permeability and selectivity. Unfortunately, PIM-1 is susceptible to physical aging and thus gradually loses its outstanding properties. In this study a polyhedral oligomeric silsesquioxane with phenethyl substituents (PhenethylPOSS) was used as a nanofiller (0–40 wt%) in the PIM-1 matrix to potentially improve the gas transport properties and prevent physical aging. The molecular mobility of the solution-cast nanocomposite films was analyzed by Broadband Dielectric Spectroscopy (BDS). Furthermore, gas permeability was determined with the time lag method (0–20 bar upstream pressure) at 35 °C for N2, O2, CH4 and CO2. KW - Broadband Dielectric Spectroscopy KW - Gas separation KW - Gas permeation KW - Polymers of intrinsic microporosity KW - Nanocomposite KW - POSS KW - PIM-1 PY - 2017 DO - https://doi.org/10.1016/j.memsci.2017.02.007 SN - 0376-7388 SN - 1873-3123 VL - 529 SP - 274 EP - 285 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-39169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Yin, Huajie A1 - Chapala, P. A1 - Bermeshev, M. A1 - Schönhals, Andreas A1 - Böhning, Martin T1 - Molecular Mobility and Physical Aging of a Highly Permeable Glassy Polynorbornene as Revealed by Dielectric Spectroscopy JF - ACS Macro Letters N2 - Polymeric membranes represent a cost- and energy efficient solution for gas separation. Recently superglassy polymers with high free volume outperform many conventional dense polymers in terms of gas permeability and selectivity. However, such polymers are prone to pronounced physical aging, resulting in a dramatic reduction in the gas permeability. Molecular mobility of polymer segments plays an important role in the physical aging and the gas transport performance of polymeric membranes. Molecular mobility and physical aging of a representative superglassy polynorbornene with very high gas permeability, PTCNSi2g, was monitored by using dielectric spectroscopy with state-of-the-art high-resolution analyzers. This work helps to shed some light on the structure−property relationship of superglassy polymers on a molecular level and to provide practical “design rules” for the development of high performance polymers for gas separation. KW - Molecular mobility KW - Gas separation membrane KW - Broadband dielectric spectroscopy KW - Polymer KW - Physical ageing PY - 2017 DO - https://doi.org/10.1021/acsmacrolett.7b00456 SN - 2161-1653 VL - 6 IS - 8 SP - 813 EP - 818 PB - ACS CY - Washington DC, USA AN - OPUS4-41354 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kästner, Claudia A1 - Lichtenstein, Dajana A1 - Lampen, Alfonso A1 - Thünemann, Andreas T1 - Monitoring the fate of small silver nanoparticles during artificial digestion JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects N2 - The report on the results of an in vitro digestion study of silver nanoparticles in presence and absenceof food. The particles were poly(acrylic acid) stabilized ultra-small silver nanoparticles with a radius of 3.1 nm and a relative size distribution width of 0.2. As food components oil, starch, skimmed milk powderand a mixture thereof were chosen. Aggregation of the particles was quantified with small-angle X-rayscattering in terms of log-normal radii distributions. Complete aggregation of the primary particles wasdetermined in the absence of food. In contrast, the presence of oil and starch initiates a disaggregationin the intestine. Only small aggregates of 6 nm radii and aggregation numbers of 7 were found in thepresence of milk powder. It prevents primary particles from etching in the gastric and intestinal juice.Our results indicate that the silver nanoparticles can pass the digestion process in a nanoscale form butundergo a strong and food-dependent transformation in their state of aggregation. KW - Small-angle X-ray scattering KW - SAXS PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-404099 DO - https://doi.org/10.1016/j.colsurfa.2016.08.013 SN - 0927-7757 SN - 1873-4359 VL - 526 SP - 76 EP - 81 PB - Elsevier B.V. AN - OPUS4-40409 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Madia, Mauro A1 - Schork, B. A1 - Bernhard, J. A1 - Kaffenberger, M. T1 - Multiple crack initiation and propagation in weldments under fatigue loading JF - 3rd International symposium on fatigue design and material defects (FDMD 2017) N2 - The work aims at addressing the modelling and implementation of criteria for multiple crack propagation, including interaction and coalescence, for a more reliable fracture mechanics-based prediction of stress-life curves for weldments. A large experimental work is presented in which micro-cracks have been made visible by heat-tinting at successive stages of fatigue life of the welded specimens. Here the correlation between the number of initiation sites and the applied stress level has been also investigated. The criteria have been implemented in in-house software, which allows multiple fatigue crack propagation, and validated against selected experimental tests. The results have shown that the modelling of multiple crack propagation and interaction is crucial for the prediction of the fatigue strength of weldments, both in finite and infinite life regime. T2 - FDMD 2017 CY - Lecco, Italy DA - 19.09.2017 KW - Weldments KW - Fatigue strength KW - Multiple crack propagation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-438593 DO - https://doi.org/10.1016/j.prostr.2017.11.108 SN - 2452-3216 VL - 7 SP - 423 EP - 430 PB - Elsevier B.V. AN - OPUS4-43859 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kowarik, Stefan A1 - Weber, C. A1 - Pithan, L. A1 - Zykov, A. A1 - Bommel, S. A1 - Carla, F. A1 - Felici, R. A1 - Knie, C. A1 - Bléger, D. T1 - Multiple timescales in the photoswitching kinetics of crystalline thin films of azobenzene-trimers JF - Journal of Physics: Condensed Matter N2 - Functional materials that exhibit photoinduced structural phase transitions are highly interesting for applications in optomechanics and mechanochemistry. It is, however, still not fully understood how photochemical reactions, which are often accompanied by molecular motion, proceed in confined and crystalline environments. Here we show that thin films of azobenzene trimers exhibit high structural order and determine the crystallographic unit cell. We demonstrate that thin film can be switched partially reversibly between a crystalline and an amorphous phase. The time constant of the photoinduced amorphisation as measured with real-time x-ray diffraction ($\approx $ 220 s) lies between the two time constants (120 s and 2870 s) of the ensemble photoisomerisation processes that are measured via optical spectroscopy. Our observation of a photoinduced shrinking of the crystalline domains indicates a cascading process, in which photoisomerisation starts at the surface of the thin film and propagates deeper into the crystalline layer by introducing disorder and generating free volume. This finding is important for the rapidly evolving research field of photoresponsive thin films and smart crystalline materials in general. KW - Azobenzene PY - 2017 DO - https://doi.org/10.1088/1361-648X/aa8654 SN - 0953-8984 SN - 1361-648X VL - 29 IS - 43 SP - Article 434001, 1 EP - 8 AN - OPUS4-42501 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kirner, Sabrina A1 - Wirth, Thomas A1 - Sturm, Heinz A1 - Krüger, Jörg A1 - Bonse, Jörn T1 - Nanometer-resolved chemical analyses of femtosecond laser-induced periodic surface structures on titanium JF - Journal of Applied Physics N2 - The chemical characteristics of two different types of laser-induced periodic surface structures (LIPSS), so-called high and low spatial frequency LIPSS (HSFL and LSFL), formed upon irradiation of titanium surfaces by multiple femtosecond laser pulses in air (30 fs, 790 nm, 1 kHz), are analyzed by various optical and electron beam based surface analytical techniques, including micro-Raman spectroscopy, energy dispersive X-ray analysis, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The latter method was employed in a high-resolution mode being capable of spatially resolving even the smallest HSFL structures featuring spatial periods below 100 nm. In combination with an ion sputtering technique, depths-resolved chemical information of superficial oxidation processes was obtained, revealing characteristic differences between the two different types of LIPSS. Our results indicate that a few tens of nanometer shallow HSFL are formed on top of a ∼150 nm thick graded superficial oxide layer without sharp interfaces, consisting of amorphous TiO2 and partially crystallized Ti2O3. The larger LSFL structures with periods close to the irradiation wavelength originate from the laser-interaction with metallic titanium. They are covered by a ∼200 nm thick amorphous oxide layer, which consists mainly of TiO2 (at the surface) and other titanium oxide species of lower oxidation states underneath. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Oxidation KW - Titanium KW - Auger electron spectroscopy PY - 2017 DO - https://doi.org/10.1063/1.4993128 SN - 0021-8979 VL - 122 IS - 10 SP - 104901, 1 EP - 9 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-41905 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauw, Brian Richard A1 - Kästner, Claudia A1 - Thünemann, Andreas T1 - Nanoparticle size distribution quantification: results of a small-angle X-ray scattering inter-laboratory comparison JF - Journal of Applied Crystallography N2 - This paper presents the first worldwide inter-laboratory comparison of small-angle X-ray scattering (SAXS) for nanoparticle sizing. The measurands in this comparison are the mean particle radius, the width of the size distribution and the particle concentration. The investigated sample consists of dispersed silver nanoparticles, surrounded by a stabilizing polymeric shell of poly(acrylic acid). The silver cores dominate the X-ray scattering pattern, leading to the determination of their radius size distribution using (i) the generalized indirect Fourier transformation method, (ii) classical model fitting using SASfit and (iii) a Monte Carlo fitting approach using McSAS. The application of these three methods to the collected data sets from the various laboratories produces consistent mean number- and volume-weighted core radii of Rn = 2.76 (6) nm and Rv = 3.20 (4) nm, respectively. The corresponding widths of the lognormal radius distribution of the particles were σn = 0.65 (1) nm and σv = 0.71 (1) nm. The particle concentration determined using this method was 3.0 (4) g l−1 or 4.2 (7) × 10−6 mol l−1. These results are affected slightly by the choice of data evaluation procedure, but not by the instruments: the participating laboratories at synchrotron SAXS beamlines, commercial and in-house-designed instruments were all able to provide highly consistent data. This demonstrates that SAXS is a suitable method for revealing particle size distributions in the sub-20 nm region (at minimum), out of reach for most other analytical methods. KW - SAXS KW - Small-angle X-ray scattering KW - Silver nanoparticles PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-422800 DO - https://doi.org/10.1107/S160057671701010X SN - 1600-5767 VL - 50 IS - 5 SP - 1280 EP - 1288 PB - (IUCr) International Union of Crystallography AN - OPUS4-42280 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sobol, Oded A1 - Nolze, Gert A1 - Saliwan Neumann, Romeo A1 - Eliezer, D. A1 - Böllinghaus, Thomas A1 - Unger, Wolfgang T1 - Novel approach to image hydrogen distribution and related phase transformation in duplex stainless steels at the sub-micron scale JF - International Journal of Hydrogen Energy N2 - The effect of electrochemical charging of hydrogen on the structure of a lean duplex stainless steel LDX 2101® (EN 1.4162, UNS S32101) was examined by both Time-of-Flight secondary ion mass spectrometry and electron back-scatter diffraction. The goal is to correlate hydrogen concentration and induced structural changes. Chemical and structural characterizations were done for the same region at the sample's surface with sub-micron spatial resolution. Regions of interest were varying in size between 50 × 50 μm and 100 × 100 μm. The results show a phase transformation of austenite to mainly a defect-rich BCC and scarcely a HCP phase. The phase transformation occurred in deuterium rich regions in the austenite. KW - Time-of-flight secondary ion mass spectrometry KW - ToF-SIMS KW - Electron backscatter diffraction KW - EBSD KW - Hydrogen-assisted cracking KW - Data fusion KW - Lean duplex stainless steel PY - 2017 DO - https://doi.org/10.1016/j.ijhydene.2017.08.016 SN - 0360-3199 VL - 42 IS - 39 SP - 25114 EP - 25120 AN - OPUS4-42022 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bachmann, Marcel A1 - Carstensen, J. A1 - Bergmann, L. A1 - dos Santos, J. F. A1 - Wu, C. S. A1 - Rethmeier, Michael T1 - Numerical simulation of thermally induced residual stresses in friction stir welding of aluminum alloy 2024-T3 at different welding speeds JF - The international journal of advanced manufacturing technology N2 - The paper deals with a numerical finite element simulation of the residual stress evolution in friction stir welding of 6 mm thick aluminum alloy AA2024-T3. The transient thermal field during the welding process was calculated with the commercial code COMSOL Multiphysics 5.0. Therefore, a thermal-pseudo-mechanical (TPM) heat source was implemented. A subsequent mechanical simulation was performed with varying hardening models for different welding speeds of 60 and 300 mm/min. The influence of softening of the material, which was due to hardening precipitation dissolution associated to the heating, was also investigated. Experiments in terms of thermocouple measurements as well as Vickers hardness and X-ray measurements of the residual stresses were conducted and compared to numerically obtained results. A qualitatively as well as quantitatively good agreement was found for different applied welding speeds. KW - Friction stir welding KW - Residual stress KW - Finite element simulation KW - Thermal softening KW - Aluminum alloy 2024-T3 PY - 2017 DO - https://doi.org/10.1007/s00170-016-9793-8 SN - 0268-3768 SN - 1433-3015 VL - 91 SP - 1443 EP - 1452 PB - Springer CY - London AN - OPUS4-40511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Leonhard, H. T1 - Oberflächendetektive im Praxiseinsatz - Schnelltest auf Korrosionsgefahr an nichtrostenden Stählen JF - cav - Chemie Produktion Anlagen Verfahren N2 - Die Passivschicht von Behältern und Rohrsystemen aus nichtrostendem Stahl ist nicht nur durch den rauen Industriealltag gefährdet. Schon im Neuzustand können Schäden entstehen, etwa durch Schleifvorgänge oder ungenügende Entfernung von Anlauffarben. TÜV SÜD Chemie Service beteiligte sich an der Prüfung eines von der BAM entwickelten Schnelltests. Das Korropad-Verfahren liefert in nur 15 Minuten eine verlässliche Aussage zum Zustand der Passivschicht. KW - Nichtrostender Stahl KW - Korrosionsschnelltest KW - KorroPad KW - Passivschicht PY - 2017 SN - ISSN 0009-2800 VL - 50. Jahrgang IS - 10-2017 SP - 34 EP - 35 PB - Konradin-Verlag Robert Kohlhammer GmbH CY - Leinfelden-Echterdingen AN - OPUS4-42735 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schröpfer, Dirk A1 - Kromm, Arne A1 - Kannengießer, Thomas T1 - Optimization of welding loads with narrow groove and application of modified spray arc process JF - Welding in the World N2 - Current efforts for lightweight design result in a growing application of high-strength fine-grained structural steel in modern constructions, e.g. mobile cranes, with yield strength from 960 MPa. The design of welded structures and welding processes becomes more challenging with increasing material strength and elastic ratios. High residual stresses are able to diminish lifetime, load capacity and component safety and should be avoided. Recent analyses have shown strong influences of heat control and restraint of the weld due to arising reaction stresses, superimposing with local residual welding stresses. Modern inverter technologies allowed the development of numerous modified spray arc processes driven by power source manufacturers, which provide virtually similar features and several benefits, enabling welding of narrower seams with reduced weld volumes and total heat inputs. This research focuses on welding loads due to modified weld seams. The global reaction forces and moments and their superposition with local residual stresses in welded components due to external shrinkage restraints were investigated using a special testing facility and XRD. The restraint intensity, weld seam geometry and welding process were varied for statistical evaluations of resulting welding loads. When welding under restraint, a reduction of the weld seam volume causes significantly lower reaction stress levels. KW - Residual stresses KW - MAG welding KW - Restraint KW - High-strength steels KW - Process parameters PY - 2017 DO - https://doi.org/10.1007/s40194-017-0484-3 SN - 1878-6669 SN - 0043-2288 VL - 61 IS - 6 SP - 1077 EP - 1087 PB - Springer CY - Berlin Heidelberg AN - OPUS4-41071 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shashev, Yury A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Evsevleev, Sergei A1 - Müller, Bernd R. A1 - Osenberg, Markus A1 - Manke, Ingo A1 - Hentschel, Manfred P. A1 - Bruno, Giovanni T1 - Optimizing the visibility of X-ray phase grating interferometry JF - Materials Testing N2 - The performance of grating interferometers coming up now for Imaging interfaces within materials depends on the efficiency (visibility) of their main component, namely the phase grating. Therefore, experiments with monochromatic synchrotron radiation and corresponding simulations are carried out. The visibility of a Phase grating is optimized by different photon energies, varying detector to grating distances and continuous rotation of the phase grating about the grid lines. Such kind of rotation changes the projected grating shapes, and thereby the distribution profiles of phase shifts. This yields higher visibilities than derived from ideal rectangular shapes. By continuous grating rotation and variation of the propagation distance, we achieve 2D visibility maps. Such maps provide the visibility for a certain combination of grating orientation and detector position. Optimum visibilities occur at considerably smaller distances than in the standard setup. KW - Synchrotron, BAMline KW - Talbot-Lau interferometer KW - X-ray imaging KW - X-ray refraction KW - Grating interferometry KW - X-ray phase contrast PY - 2017 DO - https://doi.org/10.3139/120.111097 SN - 0025-5300 VL - 59 IS - 11-12 SP - 974 EP - 980 PB - Hanser Verlag AN - OPUS4-42955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Häusler, Ines A1 - Moeck, P. A1 - Volz, K. A1 - Neumann, W. T1 - Orientation relationships of Mn0.75Ga0.25As crystallites on and within GaAs determined by scanning nano beam electron diffraction JF - Crystal Research and Technology N2 - Mn0.75Ga0.25As crystallites, partially embedded on and fully embedded within a single crystalline matrix of GaAs formed during metal organic vapor phase epitaxy (MOVPE) of Mn-rich (Mn,Ga)As on (001) oriented GaAs wafers. Phase and orientation analysis of these crystallites were performed with scanning nano beam electron diffraction (SNBED). The investigation of plan-view specimens using a liquid nitrogen cooling stage enabled the phase and orientation analysis of partially embedded ferromagnetic a-phase particles. In all specimens the following two orientation relationships (O) between the a-phase particles and the GaAs matrix were determined: O1: [1-2.0] Mn0.75Ga0.25As || [110] GaAs and [10.2] Mn0.75Ga0.25As || [-110] GaAs O2: [10.2] Mn0.75Ga0.25As || [110] GaAs and [1-2.0] Mn0.75Ga0.25As || [-110] GaAs. The study of cross-sectional specimens enabled the analysis of fully embedded crystallites. It could be unambiguously detected that a fully embedded crystallite has the structure of the atomically ordered monoclinic β' phase. The β' phase crystallite consists of two domains which are related in twin positions to each other. The orientation relations of the different particles are illustrated by color coded stereographic projections. KW - (Mn,Ga)As crystallites KW - Scanning nano beam electron diffraction KW - Crystal phase determination KW - Orientation mapping KW - STEM/TEM imaging PY - 2017 DO - https://doi.org/10.1002/crat.201600261 SN - 1521-4079 SN - 0232-1300 VL - 52 IS - 1, Special Issue: Anniversary Issue: 50 Years of Crystal Research & Technology SP - 138 EP - 145 PB - Wiley AN - OPUS4-38939 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Gorris, H.H. T1 - Perspectives and challenges of photon-upconversion nanoparticles - Part I: routes to brighter particles and quantitative spectroscopic studies JF - Analytical and Bioanalytical Chemistry N2 - Lanthanide-doped photon-upconversion nanoparticles (UCNPs) have been the Focus of many Research activities in materials and life sciences in the last 15 years because of their potential to convert light between different spectral regions and their unique photophysical properties. To fully exploit the application potential of These facinating nanomaterials, a number of challenges have to be overcome, such as the low brightness, particularly of small UCNPs, and the reliable quantification of the excitation-power-density-dependent upconversion luminescence. In this series of critical Reviews, recent developments in the design, Synthesis, optical-spectroscopic characterization, and application of UCNPs are presented with Special Focus on bioanalysis and the life sciences. Here we guide the reader from the Synthesis of UCNPs to different concepts to enhance their luminescence, including the required optical-spectroscopic assessment to quantify material Performance; surface modification strategies and bioanalytical applications as well as selected examples of the use of UCNPs as reporters in different Assay formats are addressed in part II. Future Trends and challenges in the field of upconversion are discussed with Special emphasis on UCNP Synthesis and material characterization, particularly quantitative luminescence studies. KW - Fluorescence KW - Lanthanide KW - Upconversion KW - Brightness KW - Quantification KW - Nanoparticle KW - Absolute fluorometry KW - NIR KW - IR KW - Quantum yield PY - 2017 DO - https://doi.org/10.1007/s00216-017-0499-z SN - 1618-2650 SN - 1618-2642 VL - 409 IS - 25 SP - 5855 EP - 5874 PB - Springer AN - OPUS4-41665 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Asadujjaman, Asad A1 - Kent, B. A1 - Bertin, Annabelle T1 - Phase transition and aggregation behaviour of an UCST-type copolymer poly(acrylamide-coacrylonitrile) in water: effect of acrylonitrile content, concentration in solution, copolymer chain length and presence of electrolyte JF - Soft Matter N2 - An UCST-type copolymer of acrylamide (AAm) and acrylonitrile (AN) (poly(AAm-co-AN)) was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization and its temperature-induced phase transition and aggregation behaviour studied by turbidimetry, static and dynamic light scattering, small angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM) measurements. The phase transition temperature was found to increase with increasing AN content in the copolymer, concentration of the solutions and copolymer chain length. A significant effect was observed onto the phase transition temperature by addition of different electrolytes into the copolymer solution. The copolymer chains were aggregated below the phase transition temperature and disaggregated above it. The size of the aggregates increases with increasing AN contents and concentration of the copolymer solutions below the phase transition temperature. The copolymer chains were expanded and weekly associated in solution above the phase transition temperature. A model is proposed to explain such association–aggregation behaviour of poly(AAm-co-AN) copolymers depending on AN contents and concentration of the copolymer solutions as a function of temperature. KW - Thermoresponsive polymers KW - UCST-type copolymer PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-394636 DO - https://doi.org/10.1039/c6sm02262f SN - 1744-683X SN - 1744-6848 VL - 13 IS - 3 SP - 658 EP - 669 PB - RSC AN - OPUS4-39463 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mull, Birte A1 - Möhlmann, L. A1 - Wilke, Olaf T1 - Photocatalytic degradation of toluene, butyl acetate and limonene under UV and visible light with titanium dioxide-graphene oxide as photocatalyst JF - Environments N2 - Photocatalysis is a promising technique to reduce volatile organic compounds indoors. Titanium dioxide (TiO2) is a frequently-used UV active photocatalyst. Because of the lack of UV light indoors, TiO2 has to be modified to get its working range shifted into the visible light spectrum. In this study, the photocatalytic degradation of toluene, butyl acetate and limonene was investigated under UV LED light and blue LED light in emission test chambers with catalysts either made of pure TiO2 or TiO2 modified with graphene oxide (GO). TiO2 coated with different GO amounts (0.75%–14%) were investigated to find an optimum ratio for the photocatalytic degradation of VOC in real indoor air concentrations. Most experiments were performed at a relative humidity of 0% in 20 L emission test chambers. Experiments at 40% relative humidity were done in a 1 m³ emission test chamber to determine potential byproducts. Degradation under UV LED light could be achieved for all three compounds with almost all tested catalyst samples up to more than 95%. Limonene had the highest degradation of the three selected volatile organic compounds under blue LED light with all investigated catalyst samples. KW - Photocatalysis KW - Emission test chamber KW - Volatile organic compound KW - VOC KW - Degradation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-402955 DO - https://doi.org/10.3390/environments4010009 SN - 2076-3298 VL - 4 IS - 1 SP - Article 9, 1 EP - 9 PB - MDPI CY - Basel AN - OPUS4-40295 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Joester, Maike A1 - Seifert, Stephan A1 - Emmerling, Franziska A1 - Kneipp, Janina T1 - Physiological influence of silica on germinating pollen as shown by Raman spectroscopy JF - Journal of Biophotonics N2 - The process of silicification in plants and the biochemical effects of silica in plant tissues are largely unknown. To study the molecular changes occurring in growing cells that are exposed to higher than normal concentration of silicic acid, Raman spectra of germinating pollen grains of three species (Pinus nigra, Picea omorika, and Camellia japonica) were analyzed in a multivariate classification approach that takes into account the variation of biochemical composition due to species, plant tissue structure, and germination condition. The results of principal component analyses of the Raman spectra indicate differences in the utilization of stored lipids, a changed mobilization of storage carbohydrates in the pollen grain bodies, and altered composition and/or structure of cellulose of the developing pollen tube cell walls. These biochemical changes vary in the different species. KW - Silica KW - Raman spectroscopy KW - Principal component analysis PY - 2017 DO - https://doi.org/10.1002/jbio.201600011 SN - 1864-063X SN - 1864-0648 VL - 10 IS - 4 SP - 542 EP - 552 AN - OPUS4-40090 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Joseph, A. A1 - Bernardes, C. E. S. A1 - Druzhinina, A. I. A1 - Varushchenko, R. M. A1 - Nguyen, Thi Yen A1 - Emmerling, Franziska A1 - Yuan, L. A1 - Dupray, V. A1 - Coquerel, G. A1 - Minas da Piedade, M. E. T1 - Polymorphic phase transition in 4′-hydroxyacetophenone: Equilibrium temperature, kinetic barrier, and the relative stability of Z′=1 and Z′=2 forms JF - Crystal Growth & Design N2 - Particularly relevant in the context of polymorphism is understanding how structural, thermodynamic, and kinetic factors dictate the stability domains of polymorphs, their tendency to interconvert through phase transitions, or their possibility to exist in metastable states. These three aspects were investigated here for two 4′-hydroxyacetophenone (HAP) polymorphs, differing in crystal system, space group, and number and conformation of molecules in the asymmetric unit. The results led to a ΔfGm°-T phase diagram highlighting the enantiotropic nature of the system and the fact that the Z′=1 polymorph is not necessarily more stable than its Z′=2 counterpart. It was also shown that the form II → form I transition is entropy driven and is likely to occur through a nucleation and growth mechanism, which does not involve intermediate phases, and is characterized by a high activation energy. Finally, although it has been noted that conflicts between hydrogen bond formation and close packing are usually behind exceptions from the hypothesis of Z′=1 forms being more stable than their higher Z′ analogues, in this case, the HAP polymorph with stronger hydrogen bonds (Z′=2) is also the one with higher density. KW - Polymorphism KW - Polymorphic transition KW - 4'-hydroxyacetophenone PY - 2017 DO - https://doi.org/10.1021/acs.cgd.6b01876 SN - 1528-7483 SN - 1528-7505 VL - 17 IS - 4 SP - 1918 EP - 1932 PB - ACS AN - OPUS4-40167 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pfennig, Anja A1 - Kranzmann, Axel T1 - Potential of martensitic stainless steel X5CrNiCuNb 16-4 as pipe steel in corrosive CCS environment JF - IJSSD International Journal of Environmental Science and Development N2 - Pipe steels suitable for carbon capture and storage technology (CCS) require resistance against the corrosive environment of a potential CCS-site (heat, pressure, salinity of the aquifer, CO2-partial pressure). X5CrNiCuNb16-4 has been proven to be sufficient resistant in corrosive environments, but shows rather unusual corrosion behaviour in CCS environment. Therefore differently heat treated coupons of 1.4542 were kept at T=60 °C and ambient pressure as well as p=100 bar for 700 h - 8000 h in an a) water saturated supercritical CO2 and b) CO2-saturated synthetic aquifer environment similar to on-shore CCS-sites in the Northern German Basin. Additionally fatigue tests were performed via push-pull tests with a series of 30 specimens was tested at stress amplitudes between 150 MPa and 500 MPa (sinusoidal dynamic test loads, R=-1; resonant frequency ~ 30 Hz). Best corrosion resistance in the liquid phase is achieved via normalizing prior to exposure and hardening+tempering at 670 °C leads to lowest corrosion rates in the supercritical phase. With no regard to atmosphere discontinuously ellipsoidal surface corrosion regions appear after exposure of 4000 h and more. The endurance limit of X5CrNiCuNb16-4 measured in air is reduced by more than 50% when exposed to CCS environment (maximum number of cycles (10 x 106) at a stress amplitude of 150 MPa) The scatter range TN = 1:34 is disproportionately large contributing to an overall unusual corrosion behaviour. KW - Corrosion KW - CCS KW - Carbon storage KW - Aquifer KW - Heat treatment KW - Fatigue KW - Endurance limit PY - 2017 DO - https://doi.org/10.18178/ijesd.2017.8.7.998 SN - 2010-0264 VL - 8 IS - 7 SP - 466 EP - 473 AN - OPUS4-41863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mirtschin, Nikolaus A1 - Pretsch, T. T1 - Programming of one- and two-step stress recovery in a poly(ester urethane) JF - Polymers N2 - This work demonstrates that phase-segregated poly(ester urethane) (PEU) with switching segments of crystallizable poly(1,4-butylene adipate) (PBA) can be programmed to generate two separate stress recovery events upon heating under constant strain conditions. For programming, two elongations are applied at different temperatures, followed by unloading and cooling. During the adjacent heating, two-step stress recovery is triggered. The results indicate that the magnitude of the stress recovery signals corresponds to the recovery of the two deformation stresses in reverse order. As demonstrated by further experiments, twofold stress recovery can be detected as long as the elongation at higher temperature exceeds the strain level of the deformation at lower temperature. Another finding includes that varying the lower deformation temperature enables a control over the stress recovery temperature and thus the implementation of so-called “temperature-memory effects”. Moreover, exerting only one elongation during programming enables a heating-initiated one-step stress recovery close to the deformation temperature. Based on these findings, such polymers may offer new technological opportunities in the fields of active assembly when used as fastening elements and in functional clothing when utilized for compression stockings. KW - DSC KW - Mechanical properties PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-393585 DO - https://doi.org/10.3390/polym9030098 SN - 2073-4360 VL - 9 IS - 3 SP - Article 98, 1 EP - 12 PB - MDPI CY - Basel AN - OPUS4-39358 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Juling, S. A1 - Niedzwiecka, A. A1 - Böhmert, L. A1 - Lichtenstein, D. A1 - Selve, S. A1 - Braeuning, A. A1 - Thünemann, Andreas A1 - Krause, E. A1 - Lampen, A. T1 - Protein Corona Analysis of Silver Nanoparticles Links to Their Cellular Effects JF - Journal of proteome research N2 - The breadth of applications of nanoparticles and the access to food-associated consumer products containing nanosized materials lead to oral human exposure to such particles. In biological fluids nanoparticles dynamically interact with biomolecules and form a protein corona. Knowledge about the protein corona is of great interest for understanding the molecular effects of particles as well as their fate inside the human body. We used a mass spectrometry-based toxicoproteomics approach to elucidate mechanisms of toxicity of silver nanoparticles and to comprehensively characterize the protein corona formed around silver nanoparticles in Caco-2 human intestinal epithelial cells. Results were compared with respect to the cellular function of proteins either affected by exposure to nanoparticles or present in the protein corona. A transcriptomic data set was included in the analyses in order to obtain a combined multiomics view of nanoparticle-affected cellular processes. A relationship between corona proteins and the proteomic or transcriptomic responses was revealed, showing that differentially regulated proteins or transcripts were engaged in the same cellular signaling pathways. Protein corona analyses of nanoparticles in cells might therefore help in obtaining information about the molecular consequences of nanoparticle treatment. KW - Silver nanoparticles KW - Protein KW - Small-angle X-ray scattering KW - SAXS PY - 2017 DO - https://doi.org/10.1021/acs.jproteome.7b00412 SN - 1535-3893 SN - 1535-3907 VL - 16 IS - 11 SP - 4020 EP - 4034 PB - Americal Chemical Society AN - OPUS4-42688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Naresh-Kumar, G. A1 - Vilalta-Clemente, A. A1 - Jussila, H. A1 - Winkelmann, Aimo A1 - Nolze, Gert A1 - Vespucci, S. A1 - Nagarajan, S. A1 - Wilkinson, A. J. A1 - Trager-Cowan, C. T1 - Quantitative imaging of anti-phase domains by polarity sensitive orientation mapping using electron backscatter diffraction JF - Scientific Reports N2 - Advanced structural characterisation techniques which are rapid to use, non-destructive and structurally definitive on the nanoscale are in demand, especially for a detailed understanding of extended-defects and their influence on the properties of materials. We have applied the electron backscatter diffraction (EBSD) technique in a scanning electron microscope to non-destructively characterise and quantify antiphase domains (APDs) in GaP thin films grown on different (001)Si substrates with different offcuts. We were able to image and quantify APDs by relating the asymmetrical intensity distributions observed in the EBSD patterns acquired experimentally and comparing the same with the dynamical electron diffraction simulations. Additionally mean angular error maps were also plotted using automated cross-correlation based approaches to image APDs. Samples grown on substrates with a 4° offcut from the [110] do not show any APDs, whereas samples grown on the exactly oriented substrates contain APDs. The procedures described in our work can be adopted for characterising a wide range of other material systems possessing non-centrosymmetric point groups. KW - Polarity KW - Semiconductor KW - Antiphase boundary PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-420167 SN - 2045-2322 VL - 7 SP - Article 10916, 1 EP - 10 AN - OPUS4-42016 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Miccoli, Lorenzo A1 - Müller, U. A1 - Pospisil, S. T1 - Rammed earth walls strengthened with polyester fabric strips: Experimental analysis under in-plane cyclic loading JF - Construction and Building Materials N2 - This study analyses the mechanical behaviour under pseudo-dynamic loading of structural elements built in rammed earth and strengthened with polyester fabric strips. This strengthening technique was developed to exploit the strength potential of rammed earth and to solve its lack of tensile strength. For this reason, in-plane cyclic tests were carried out to investigate the shear behaviour of unstrengthened and strengthened walls. The strengthening technique requires low-tech equipment and workmanship, uses readily available, not expensive and industrially standardised materials. The experimental results were analysed in terms of stiffness degradation, energy dissipation capacity and equivalent viscous damping. Although the unstrengthened and strengthened walls confirmed a limited ductile behaviour, the findings confirm that the strengthening contributes to limit the spread of the diagonal cracks and provide an increase of strength in terms of horizontal load and displacement capacity. KW - Rammed earth KW - Pseudo-dynamic loads KW - Shear-compression tests KW - Strengthening KW - Polyester fabric strips PY - 2017 DO - https://doi.org/10.1016/j.conbuildmat.2017.05.115 IS - 149 SP - 29 EP - 36 PB - Elsevier Ltd. AN - OPUS4-40497 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Stegemann, Robert A1 - Cabeza, Sandra A1 - Lyamkin, V. A1 - Bruno, Giovanni A1 - Pittner, Andreas A1 - Wimpory, Robert A1 - Boin, M. A1 - Kreutzbruck, Marc T1 - Residual stress characterization of steel TIG welds by neutron diffraction and by residual magnetic stray field mappings JF - Journal of Magnetism and Magnetic Materials N2 - The residual stress distribution of tungsten inert gas welded S235JRC+C plates was determined by means of neutron diffraction(ND). Large longitudinal residual stresses with maxima around 600 MPa were found. With these results as reference, the evaluation of residual stress with high spatial resolution GMR (giant magneto resistance) sensors was discussed. The experiments performed indicate a correlation between changes in residual stresses (ND) and the normal component of local residual magnetic stray fields (GMR). Spatial variations in the magnetic field strength perpendicular to the welds are in the order of the magnetic field of the earth. KW - GMR KW - Magnetic stray field KW - Neutron diffraction KW - Residual stress KW - TIG-welding PY - 2017 DO - https://doi.org/10.1016/j.jmmm.2016.11.102 SN - 0304-8853 SN - 1873-4766 VL - 426 SP - 580 EP - 587 PB - Elsevier CY - Amsterdam AN - OPUS4-38678 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dixneit, Jonny A1 - Kromm, Arne A1 - Boin, M. A1 - Wimpory, Robert A1 - Kannengießer, Thomas A1 - Gibmeier, J. A1 - Schröpfer, Dirk T1 - Residual stresses of LTT welds in large-scale components JF - Welding in the World N2 - Residual stresses of welds become more and more important influencing cold cracking as well as the fatigue life of welded components. Low transformation temperature (LTT) filler materials offer the opportunity to alter the residual stresses already during the welding process by means of ad- justed martensite phase transformation temperature (MS). In the current paper, welding residual stresses are studied putting the focus on MS while joining heavy steel sections with a thickness of 20 and 25 mm, respectively. The residual stress state was determined at the top surface using X-ray diffraction as well as in the bulk by neutron diffraction. The results com- pare the residual stresses present in a conventional weld and LTT welds when multi-pass welding of large-scale compo- nents was applied. Repeated phase transformation in the case of the LTT weld is more vital for the residual stresses present in the real-life-like joints. This accounts for the top surface in longitudinal direction but is most pronounced for the bulk of the welds. Detrimental tensile residual stresses are mainly re- duced in the bulk in comparison to a conventional filler wire even in multi-pass welds of thick steel sections. T2 - IIW AA 2016 CY - Melbourne, Australia DA - 10.07.2016 KW - LTT KW - Welding residual stress KW - Phase transformation KW - Interpass temperature PY - 2017 DO - https://doi.org/10.1007/s40194-017-0502-5 SN - 0043-2288 SN - 1878-6669 VL - 61 IS - 6 SP - 1089 EP - 1097 PB - Springer CY - Heidelberg AN - OPUS4-41169 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Gottlieb, Cassian A1 - Millar, Steven A1 - Günther, Tobias A1 - Wilsch, Gerd T1 - Revealing hidden spectral information of chlorine and sulfur in data of a mobile Laser-induced Breakdown Spectroscopy system using chemometrics JF - Spectrochimica Acta Part B - Atomic Spectroscopy N2 - For the damage assessment of reinforced concrete structures the quantified ingress profiles of harmful species like chlorides, sulfates and alkali need to be determined. In order to provide on-site analysis of concrete a fast and reliable method is necessary. Low transition probabilities as well as the high ionization energies for chlorine and sulfur in the near-infrared range makes the detection of Cl I and S I in low concentrations a difficult task. For the on-site analysis a mobile LIBS-system (k = 1064 nm, Epulse ≤ 3 mJ, t = 1.5 ns) with an automated scanner has been developed at BAM. Weak chlorine and sulfur signal intensities do not allow classical univariate analysis for process data derived from the mobile system. In order to improve the analytical performance multivariate analysis like PLS-R will be presented in this work. A comparison to standard univariate analysis will be carried out and results covering important parameters like detection and quantification limits (LOD, LOQ) as well as processing variances will be discussed (Allegrini and Olivieri, 2014 [1]; Ostra et al., 2008 [2]). It will be shown that for the first time a low cost mobile system is capable of providing reproducible chlorine and sulfur analysis on concrete by using a low sensitive system in combination with multivariate evaluation. KW - LIBS KW - Chemometrics KW - Building materials PY - 2017 DO - https://doi.org/10.1016/j.sab.2017.04.001 SN - 0584-8547 VL - 132 SP - 43 EP - 49 PB - Elsevier B.V. AN - OPUS4-40066 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grohmann, Maria A1 - Müller, Sabine A1 - Niederleithinger, Ernst A1 - Sieber, S. T1 - Reverse time migration: introducing a new imaging technique for ultrasonic measurements in civil engineering JF - Near Surface Geophysics N2 - Ultrasonic echo testing is widely used in non-destructive testing in civil engineering to investigate concrete structures, to measure thickness, and to locate and characterise built-in components or inhomogeneities. Currently, synthetic aperture focusing techniques are mostly used for imaging. These algorithms are highly developed but have some limitations. For example, it is not possible to image the lower boundary of built-in components like tendon ducts or vertical reflectors. We adopted reverse time migration for non-destructive testing in civil engineering in order to improve the imaging of complicated structures in concrete. By using the entire wavefield, including waves reflected more than once, there are fewer limitations compared to synthetic aperture focusing technique algorithms. As a drawback, the required computation is significantly higher than that for the techniques currently used. Simulations for polyamide and concrete structures showed the potential for non-destructive testing. The simulations were followed by experiments at a polyamide specimen. Here, having acquired almost noise-free measurement data to test the algorithm, we were able to determine the shape and size of boreholes with sufficient accuracy. After these successful tests, we performed experiments at a reinforced concrete foundation slab. We obtained information from the data by reverse time migration, which was not accessible by traditional imaging. The imaging of the location and structure of the lower boundary of the concrete foundation slab was improved. Furthermore, vertical reflectors inside the slab were imaged clearly, and more flaws were found. It has been shown that reverse time migration is a step forward in ultrasonic testing in civil engineering. KW - Ultrasonic echo technique KW - Reverse time migration PY - 2017 DO - https://doi.org/10.3997/1873-0604.2017006 SN - 1569-4445 SN - 1873-0604 VL - 15 IS - 3 SP - 242 EP - 258 PB - Wiley AN - OPUS4-41921 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dieck, S. A1 - Rosemann, Paul A1 - Kromm, Arne A1 - Halle, T. T1 - Reversed austenite for enhancing ductility of martensitic stainless steel JF - IOP Conf. Series: Materials Science and Engineering N2 - The novel heat treatment concept, “quenching and partitioning” (Q&P) has been developed for high strength steels with enhanced formability. This heat treatment involves quenching of austenite to a temperature between martensite start and finish, to receive a several amount of retained austenite. During the subsequent annealing treatment, the so called partitioning, the retained austenite is stabilized due to carbon diffusion, which results in enhanced formability and strength regarding strain induced austenite to martensite transformation. In this study a Q&P heat treatment was applied to a Fe-0.45C-0.65Mn-0.34Si-13.95Cr stainless martensite. Thereby the initial quench end temperature and the partitioning time were varied to characterize their influence on microstructural evolution. The microstructural changes were analysed by dilatometer measurements, X-ray diffraction and scanning electron microscopy, including electron backscatter diffraction. Compression testing was made to examine the mechanical behaviour. It was found that an increasing partitioning time up to 30 min leads to an enhanced formability without loss in strength due to a higher amount of stabilized retained and reversed austenite as well as precipitation hardening. T2 - 19th Chemnitz Seminar on Materials Engineering – 19. Werkstofftechnisches Kolloquium CY - Chemnitz, Germany DA - 16.03.2017 KW - Quenching and partitioning KW - Martensitic stainless steels KW - Heat treatment KW - Transformation induced plasticity KW - High ductility PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395328 DO - https://doi.org/10.1088/1757-899X/181/1/012034 SN - 1757-899X SN - 1757-8981 VL - 181 IS - Conference 1 SP - Article UNSP 012034, 1 EP - 8 PB - IOP Publishing CY - Bristol, UK AN - OPUS4-39532 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Costo, R. A1 - Veintemillas-Verdaguer, S. A1 - del Puerto Morales, M. A1 - Thünemann, Andreas T1 - SAXS analysis of single- and multi-core iron oxide magnetic nanoparticles JF - Journal of Applied Crystallography N2 - This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1 and p2 are single-core particles, while p3 and p4 are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0.08, 0.13, 0.08 and 0.12. The cores are arranged as a clustered network in the form of dense mass fractals with a fractal dimension of 2.9 in the multi-core particles p3 and p4, but the cores are well separated from each other by a protecting organic shell. The radii of gyration of the mass fractals are 48 and 44 nm, and each network contains 117 and 186 primary particles, respectively. The radius distributions of the primary particle were confirmed with transmission electron microscopy. All particles contain purely maghemite, as shown by X-ray absorption fine structure spectroscopy KW - Superparamagnetic nanoparticles KW - Iron oxide KW - Reference materials KW - SAXS KW - Small-angle x-ray scattering KW - XANES KW - X-ray absorption near-edge structure KW - X-ray absorption fine structure PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-395948 DO - https://doi.org/10.1107/S1600576717002370 SN - 1600-5767 VL - 50 IS - Part 2 SP - 481 EP - 488 PB - (IUCr) International Union of Crystallography AN - OPUS4-39594 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bonse, Jörn T1 - Scattering on scattering JF - Light: Science & Applications N2 - Ultrafast experiments can reveal the spatiotemporal dynamics of nanostructure formation via scattering in background-free optical dark-field microscopy. KW - Ultrafast microscopy KW - Scattering KW - Darkfield microscopy KW - Laser ablation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-411596 DO - https://doi.org/10.1038/lsa.2017.88 SN - 2047-7538 VL - 6 SP - e17088, 1 EP - 2 PB - Springer Nature AN - OPUS4-41159 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Leonhard, H. T1 - Schnelltest auf Korrosionsgefahr - KorroPad JF - ProzessTechnik N2 - Rostfreie Stähle werden in prozesstechnischen Anlagen oft extremen Umgebungsbedingungen ausgesetzt. Eine schützende Passivschicht an der Oberfläche nichtrostender Stähle sorgt dafür, dass es zu keiner Materialauflösung kommt. Wenn diese unvollständig oder beschädigt ist, kann es zu Komplikationen kommen. Lesen Sie im Artikel, wie die von TÜV SÜD Chemie Service erprobte Methode funktioniert, mit der die Passivschicht überprüft werden kann. KW - Nichtrostender Stahl KW - Korrosionsschnelltest KW - KorroPad KW - Passivschicht PY - 2017 SN - 2198-0691 IS - 4 SP - 84 EP - 85 PB - Fachwelt Verlag CY - Stuttgart AN - OPUS4-43185 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Resch-Genger, Ute A1 - Pilch, A. A1 - Würth, Christian A1 - Kaiser, Martin A1 - Wawrzynczyk, D. A1 - Kurnatowska, M. A1 - Arabasz, S. A1 - Prorok, K. A1 - Samoc, M. A1 - Strek, W. A1 - Bednarkiewicz, A. T1 - Shaping luminescent properties of Yb3+ and Ho3+ co-doped upconverting core-shell ß-NaYF4 nanoparticles by dopant distribution and spacing JF - Small N2 - At the core of luminescence color and lifetime Tuning of rare earth doped upconverting nanoparticles (UCNPs), is the understanding of the Impact of the particle architecture for commonly used sensitizer (S) and activator (A) Ions. In this respect, a series of core@Shell NaYF4 UCNPs doped with Yb3+ and Ho3+ ions are presented here, where the same dopant concentrations are distributed in different particle architectures following the scheme: YbHo core and YbHo@..., ...@YbHo, Yb@Ho, Ho@Yb, YbHo@Yb, and Yb@YbHo core-Shell NPs. As refealed by quantitative steady-state and time-resolved luminescence studies, the relative spatial Distribution of the A and S ions in the UCNPs and their protection from surface quenching has a critical Impact on ther luminescence characteristics. Although the increased amount of Yb3+ Ions boosts UCNP Performance by amplifying the Absorption, the Yb3+ ions can also efficiently dissipate the energy stored in the material through energy Migration to the surface, thereby reducing the Overall energy Transfer Efficiency to the activator ions. The results provide yet another proof that UC Phosphor chemistry combined with materials Engineering through intentional core@shell structures may help to fine-tune the luminescence Features of UCNPs for their specific future applications in biosensing, bioimaging, photovoltaics, and Display technologies. KW - Fluorescence KW - Upconversion KW - NIR KW - Nonlinear KW - Nanoparticle KW - Surface chemistry KW - Quantum yield KW - Liftetime KW - Nanocrystal KW - Lanthanide KW - Ho(III) KW - Yb(III) KW - Mechanism KW - Absolute flourescence KW - Excitation power density dependence PY - 2017 DO - https://doi.org/10.1002/smll.201701635 SN - 1613-6810 VL - 13 IS - 47 SP - 1701635, 1 EP - 13 PB - WILEY-VCH Verlag GmbH & co. KGaA CY - Weinheim AN - OPUS4-43629 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hönig, Gerald A1 - Westerkamp, S. A1 - Hoffmann, A. A1 - Callsen, G. T1 - Shielding electrostatic fields in polar semiconductor nanostructures JF - Physical Review Applied N2 - Polar semiconductor materials enable a variety of classic and quantum-light sources, which are optimized continuously. However, one key problem—the inherent electric crystal polarization of such materials—remains unsolved and deteriorates the radiative exciton decay rate. We suggest a sequence of reverse interfaces to compensate these polarization effects, while the polar, natural crystal growth direction is maintained. Former research approaches, like growth on less-polar crystal planes or even the stabilization of unnatural phases, never reached industrial maturity. In contrast, our concept provides a way for the development of ultrafast devices based on established growth processes for polar materials, while the electric potential landscape becomes adjustable. KW - Piezopolarisation KW - Spontane Polarisation KW - Halbleiterphysik KW - Nanophysik KW - Optoelektronik PY - 2017 DO - https://doi.org/10.1103/PhysRevApplied.7.024004 SN - 2331-7019 VL - 7 IS - 2 SP - 024004-1 EP - 024004-12 PB - American Physical Society CY - College Park, MD 20740-3844 AN - OPUS4-39125 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lehmann, Jens A1 - Leonhard, H. T1 - Sichere Werkstoffauswahl - Korrosionsschnelltest für nichtrostende Stähle JF - Konstruktion N2 - Anlagenkomponenten aus nichtrostendem Stahl sind durch eine Passivschicht auf der Oberfläche vor Korrosion geschützt. Ist diese unvollständig ausgebildet oder beschädigt, geht der Schutz verloren. Hohe Investitionen für Reparaturen und Instandhaltung können die Folge sein. TÜV Süd Chemie Service beteiligte sich an der Prüfung eines von der Bundesanstalt für Materialforschung und -prüfung (BAM) entwickelten Verfahrens zur Charakterisierung der Korrosionsbeständigkeit der Passivschicht. Der KorroPad-Schnelltest liefert in nur 15 Minuten ein valides Prüfergebnis. KW - Nichtrostender Stahl KW - Korrosionsschnelltest KW - KorroPad KW - Passivschicht PY - 2017 SN - 0720-5953 VL - 69 IS - 11-12 SP - IW10 EP - IW11 PB - Springer-VDI-Verlag GmbH & Co. KG CY - Düsseldorf AN - OPUS4-43228 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lauer, Franziska A1 - Seifert, Stephan A1 - Kneipp, Janina A1 - Weidner, Steffen T1 - Simplifying the preparation of pollen grains for MALDI-TOF MS classification JF - International Journal of Molecular Sciences N2 - Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) is a well-implemented analytical technique for the investigation of complex biological samples. In MS, the sample preparation strategy is decisive for the success of the measurements. Here, sample preparation processes and target materials for the investigation of different pollen grains are compared. A reduced and optimized sample preparation process prior to MALDI-TOF measurement is presented using conductive carbon tape as target. The application of conductive tape yields in enhanced absolute signal intensities and mass spectral pattern information, which leads to a clear separation in subsequent pattern analysis. The results will be used to improve the taxonomic differentiation and identification, and might be useful for the development of a simple routine method to identify pollen based on mass spectrometry. KW - MALDI KW - Conductive carbon tape KW - Pollen KW - Sample pretreatment KW - Principal component analysis PY - 2017 DO - https://doi.org/10.3390/ijms18030543 SN - 1422-0067 SN - 1661-6596 VL - 18 IS - 3 SP - 543-1 EP - 543-11 PB - MDPI AN - OPUS4-41733 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Philippen, Jan A1 - Guguschev, Christo A1 - Klimm, Detlef ED - Kuech, Thomas F. ED - Feigelson, Robert R. ED - Nakajima, K. ED - Stringfellow, G.B. T1 - Single crystal fiber growth of cerium doped strontium yttrate, SrY2O4:Ce3+ JF - Journal of Crystal Growth N2 - First single crystal fibers of cerium doped Strontium yttrate were fabricated using the laser-heated pedestal growth technique. Through thermodynamic Equilibrium calculations and by high-temperature mass spectrometry suitable growth conditions could be determined. The atmosphere played an important role during crystallization. It affected the composition shift, on the one hand, and the valence state of cerium, on the other hand. These dependencies can be explained by combining X-ray diffraction, elemental analysis, and optical spectroscopy. Crystallization in slightly reducing nitrogen atmosphere proved to be a reasonable choice, because evaporation is suppressed and trivalent cerium is stabilized. Strong green emission that depends on the Oxygen fugacity during crystallization could be excited using UV light. Optical properties of SrY2O4:Ce3+ were measured for the first time. KW - Laser heated pedestal growth KW - Oxides KW - Strontium yttrate KW - Single crystal fiber KW - LED phosphors PY - 2017 DO - https://doi.org/10.1016/j.jcrysgro.2016.11.033 SN - 0022-0248 SN - 1873-5002 VL - 459 SP - 17 EP - 22 PB - Elsevier CY - Amsterdam AN - OPUS4-39496 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietzsch, Michael A1 - Andrusenko, Iryna A1 - Branscheid, Robert A1 - Emmerling, Franziska A1 - Kolb, Ute A1 - Tremel, Wolfgang T1 - Snapshots of calcium carbonate Formation - a step by step analysis JF - Zeitschrift für Kristallographie - Crystalline Materials N2 - Recent advances in our understanding of CaCO, nucleation from solution have provoked new and challenging questions. We have studied CaC03 formation using precipitation by carbonate ester hydrolysis which ensures precipitation from a strictly homogeneous solution state and allows “titrating” carbonate to a solution with a given Ca2+ concentration on a timescale suited for kinetic studies. Nucleation and crystallization were traced by combining dynamic light Scattering (DLS) and transmission electron microscopy (TEM). DLS served as in situ technique to identify the nucleation time, to monitor particle size evolution, to discriminate different precipitation mechanisms and to validate reproducibility. TEM snapshots taken during different stages of the precipitation process identified different phases and morphologies. At a high level of supersaturation homogeneous nucleation in solution led to the formation of amorphous CaC03 particles (diameter=30 nm), which transformed via vaterite to calcite. Nucleation occurred uniformly in solution which appears to be unique for the CaC03 System. In the presence of Na-polymethacrylate (Na-PMA), heterogeneous nucleation was suppressed and Ca-polymer aggregates were formed in the prenucleation stage. Beyond a critical threshold supersaturation CaC03 particles formed in solution outside of these aggregates. The nucleation process resembled that without additive, indicating that Na-PMA exerts only a minor effect on the CaC03 nucleation. In the postnucleation stage, the polymer led to the formation of extended liquid-like networks, which served as a precursor phase for solid ACC particles that formed alongside the network. KW - biomineralization KW - calcium carbonate KW - nucleation KW - polymer additives PY - 2017 DO - https://doi.org/10.1515/zkri-2016-1973 SN - 2194-4946 SN - 2196-7105 VL - 232 IS - 1-3 SP - 255 EP - 265 PB - De Gruyter CY - Berlin AN - OPUS4-39863 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hennig, C. A1 - Weiss, S. A1 - Kraus, Werner A1 - Kretzschmar, J. A1 - Scheinost, A.C. T1 - Solution species and crystal structure of Zr(IV) acetate JF - Inorganic Chemistry N2 - Complex formation and the coordination of zirconium with acetic acid were investigated with Zr K-edge extended X-ray absorption fine structure spectroscopy (EXAFS) and single-crystal diffraction. Zr K-edge EXAFS spectra show that a stepwise increase of acetic acid in aqueous solution with 0.1 M Zr(IV) leads to a structural rearrangement from initial tetranuclear hydrolysis species [Zr4(OH)8(OH2)16]8+ to a hexanuclear acetate species Zr6(O)4(OH)4(CH3COO)12. The solution species Zr6(O)4(OH)4(CH3COO)12 was preserved in crystals by slow evaporation of the aqueous solution. Single-crystal diffraction reveals an uncharged hexanuclear cluster in solid Zr6(μ3-O)4(μ3-OH)4(CH3COO)12·8.5H2O. EXAFS measurements show that the structures of the hexanuclear zirconium acetate cluster in solution and the solid state are identical. KW - Complex formation KW - Crystal structure KW - Zr(iV) compounds PY - 2017 DO - https://doi.org/10.1021/acs.inorgchem.6b01624 SN - 0020-1669 SN - 1520-510X VL - 56 IS - 5 SP - 2473 EP - 2480 PB - ACS AN - OPUS4-39677 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Szczerba, Wojciech A1 - Schneider, M. A1 - Żukrowski, J. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Riesemeier, Heinrich A1 - Sikora, M. A1 - Mandel, K. T1 - Spectroscopic Study of the Role of Metal Ions in the Adsorption Process of Phosphate in Nanoscaled Adsorbers Based on Metal (Zn/ Fe/Zr) Oxyhydroxides JF - The Journal of Physical Chemistry C N2 - Currently great effort is made to find materials and technologies for the recycling of phosphate from wastewater. Herein, we present an in-depth study of the Phosphate adsorption mechanism of a promising adsorber material, a Zn−Fe−Zr oxyhydroxide-based nanostructured precipitate. The behavior of the multicomponent nanomaterial, consisting of both crystalline and amorphous parts, is investigated via X-ray absorption fine structure spectroscopy and Mössbauer spectroscopy, revealing the importance of the nanostructured composition for the phosphate adsorption. We found evidence that adsorption takes place especially in the vicinity of iron sites in the amorphous part of the material. KW - Zn-Fe-Zr nanoparticles KW - Adsorption of phosphate KW - XAFS KW - Catalysis PY - 2017 DO - https://doi.org/10.1021/acs.jpcc.7b04773 SN - 1932-7447 VL - 121 IS - 45 SP - 25033 EP - 25042 PB - ACS Publications AN - OPUS4-43348 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rudenko, A. A1 - Colombier, J.-P. A1 - Höhm, S. A1 - Rosenfeld, A. A1 - Krüger, Jörg A1 - Bonse, Jörn A1 - Itina, T.E. T1 - Spontaneous periodic ordering on the surface and in the bulk of dielectrics irradiated by ultrafast laser: a shared electromagnetic origin JF - Scientific Reports N2 - Periodic self-organization of matter beyond the diffraction limit is a puzzling phenomenon, typical both for surface and bulk ultrashort laser processing. Here we compare the mechanisms of periodic nanostructure formation on the surface and in the bulk of fused silica. We show that volume nanogratings and surface nanoripples having subwavelength periodicity and oriented perpendicular to the laser polarization share the same electromagnetic origin. The nanostructure orientation is defined by the near-field local enhancement in the vicinity of the inhomogeneous scattering centers. The periodicity is attributed to the coherent superposition of the waves scattered at inhomogeneities. Numerical calculations also support the multipulse accumulation nature of nanogratings formation on the surface and inside fused silica. Laser surface processing by multiple laser pulses promotes the transition from the high spatial frequency perpendicularly oriented nanoripples to the low spatial frequency ripples, parallel or perpendicular to the laser polarization. The latter structures also share the electromagnetic origin, but are related to the incident field interference with the scattered far-field of rough non-metallic or transiently metallic surfaces. The characteristic ripple appearances are predicted by combined electromagnetic and thermo-mechanical approaches and supported by SEM images of the final surface morphology and by time-resolved pump-probe diffraction measurements. KW - Laser-induced periodic surface structures (LIPSS) KW - Femtosecond laser KW - Nanostructures KW - Dielectrics KW - Electromagnetic scattering PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-421747 UR - https://www.nature.com/articles/s41598-017-12502-4 DO - https://doi.org/10.1038/s41598-017-12502-4 SN - 2045-2322 VL - 7 SP - Article 12306, 1 EP - 14 PB - Springer Nature AN - OPUS4-42174 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pauli, Jutta A1 - Hoffmann, Katrin A1 - Würth, Christian A1 - Behnke, Thomas A1 - Resch-Genger, Ute T1 - Standardization of fluorescence measurements in the UV/vis/NIR/IR JF - Standardization of Fluorescence Measurements in the UV/vis/NIR/IR N2 - Photoluminescence techniques are amongst the most widely used Tools in the life sciences, with new and exciting applications in medical diagnostics and molecular Imaging continuously emerging. Advantages include their comparative ease of use, unique sensitivity, non-invasive character, and potential for Multiplexing, remote sensing, and miniaturization. General drawbacks are, however, signals, that contain unwanted wavelength- and polarization contributions from Instrument-dependent effects, which are also time-dependent due to aging of Instrument-components, and difficulties to measure absolute flourescence entensities. Moreover, scattering Systems require Special measurement geometries and the interest in new optical Reporters with Emission > 1000 nm strategies for reliable measurements in the second diagnostic for the comparison of material Performance and the rational designg of new flourophores with improved properties. Here, we present strategies to versatile method-adaptable liquid and solid flourescence Standards for different flourescence paramters including traceable Instrument calibration procedures and the design of integrating spere setups for the absolute measurements of emission spectra and Quantum yields in the wavelength Region of 350 to 1600 nm. Examples are multi-Emitter glasses, spectral flourescence Standards, and quantum yield Standards for the UV/vis/NIR. T2 - Conference on Molecular-Guided Surgery - Molecules, Devices, and Applications III CY - San Francisco, CA, USA DA - 28.01.2017 KW - Fluorescence KW - Reference material KW - Standard KW - Calibration KW - Nanoparticle KW - Absolute flourometry KW - Integrating sphere spectroscopy KW - NIR KW - IR KW - Quantum yield standard KW - Emission standards PY - 2017 SN - 978-1-5106-0539-8 DO - https://doi.org/10.1117/12.2255728 SN - 0277-786X VL - 10049 SP - 1 PB - Proceedings of SPIE AN - OPUS4-41783 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Marko, A. A1 - Graf, B. A1 - Rethmeier, Michael T1 - Statistical analysis of weld bead geometry in Ti6Al4V laser cladding JF - Materials Testing N2 - The process of laser cladding has become more important during recent years because of its broad application for cladding, repair or additive manufacturing. In the field of mechanical engineering, one use is the repair of turbine blades. For high quality and reliability of the repaired components, it is necessary to adjust the weld bead geometry to the specific repair task. The bead geometry influences the metallurgical bonding and the degree of dilution as well as the formation of defects like pores or cracks. Therefore, it is important to know the effects of the different parameters on the welding bead. A valuable tool to meet this industrial challenge is the design of experiments (DoE). In this context, the user can choose between a huge number of test plans. Greater Profit of information is expected by a larger test range. In order to confirm the acceptance, a five-step full factorial test plan is compared to a central composite design in this paper. Moreover, the limits of the experimental range are indicated and restrictions can be derived. As the results show, the essential effects are detected with a full factorial test plan as well as with a central composite design. Merely the effect strength could not always be specified unambiguously. On this account and in consideration of cost efficiency, the use of central compound design is recommended in industrial applications. KW - Laser metal deposition KW - Design of experiments KW - Laser cladding KW - Cladding parameter KW - Additive manufacturing PY - 2017 DO - https://doi.org/10.3139/120.111077 SN - 0025-5300 SN - 2195-8572 VL - 59 IS - 10 SP - 837 EP - 843 PB - Carl Hanser Verlag CY - München AN - OPUS4-42882 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cabeza, Sandra A1 - Mishurova, Tatiana A1 - Garces, G. A1 - Requena, G. A1 - Bruno, Giovanni A1 - Sevostianov, I. T1 - Stress-induced damage evolution in cast AlSi12CuMgNi alloy with one- and two ceramic reinforcements JF - Journal of Material Science N2 - Two composites, consisting of an as-cast AlSi12CuMgNi alloy reinforced with 15%vol. Al2O3 short fibres and with 7%vol. Al2O3 short fibres + 15%vol. SiC particles were studied. Synchrotron computed tomography disclosed distribution, orientation, and volume fraction of the different phases. In-situ compression tests during neutron diffraction in direction parallel to the fibres plane revealed the load partition between phases. Internal damage (fragmentation) of the Si phase and Al2O3 fibres was directly observed in CT reconstructions. Significant debonding between Al-matrix and SiC particles was also found. Finally, based on the Maxwell scheme, a micro-mechanical model was utilized for the new composite with two ceramic reinforcements; it rationalizes the experimental data, and predicts the evolution of all internal stress components in each phase. KW - Computed tomography KW - Metal matrix composite KW - Load partition KW - Neutron diffraction PY - 2017 DO - https://doi.org/10.1007/s10853-017-1182-7 SN - 0022-2461 SN - 1573-4803 VL - 52 IS - 17 SP - 10198 EP - 10216 PB - Springer AN - OPUS4-40572 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -