TY - CONF A1 - Maaß, Robert T1 - Tracing structural dynamics in metallic glasses during cryogenic cycling N2 - Highly unrelaxed structural states of metallic glasses have often advantageous mechanical properties. Since metallic glasses continuously relax with time (age) or inherently are well relaxed after processing, methods to uniformly rejuvenate the material are needed. One approach that has received attention is the so-called cryogenic-cycling method, during which a metallic glass is repeatedly immersed into liquid nitrogen. In some cases, cryogenic cycling is truly efficient in increasing the stored excess enthalpy of metallic glasses, but it does not seem to be universally applicable to all alloys and structural states. The origins for these differences remain unclear due to our limited understanding of the underlying structural evolution. In order to shed more light onto the fundamental structural processes of cryogenic cycling, we pursue in-situ x-ray photon correlation spectroscopy (XPCS) to trace the atomic-scale structural dynamics of a Zr-based metallic glass in two different structural states (ribbon and bulk metallic glass). This method allows calculating the relaxation times as a function of time throughout the thermal cycling. It is found that the investigated glasses exhibit heterogeneous structural dynamics at 300 K, which changes to monotonic aging at 78 K. Cryogenic cycling homogenizes the relaxation time distribution for both structural states. This effect is much more pronounced in the ribbon, which is the only structural state that rejuvenates upon cycling. We furthermore reveal how fast atomic-scale dynamics is correlated with long-time average structural relaxation times irrespective of the state, and that the ribbon exhibits unexpected additional fast atomic-scale relaxation in comparison to the plate material. Overall, a picture emerges that points towards heterogeneities in fictive temperature as a requirement for cryogenic energy storage. T2 - MRS Fall 2020 - Invited Talk CY - Boston, MA, USA DA - 27.11.2020 KW - Relaxation metallic glasses PY - 2020 AN - OPUS4-59542 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Huang, Yanliang A1 - Liu, Xiangju A1 - Zhang, Qichao A1 - Xu, Yong A1 - Kunte, Hans-Jörg A1 - De Marco, Roland T1 - Hydrogen release from carbon steel in chloride solution under anodic polarization N2 - The hydrogen permeation current increase was noticed for carbon steel in 0.5 mol/L NaCl solution under strong anodic potentials, which is contrary to the common understanding. Hydrogen permeation under cathodic potentials has been widely studied because of possible hydrogen embrittlement failures of high strength steels in seawater, but investigations of anodic polarization on hydrogen permeation are fairly rare, as the hydrogen evolution reaction shall be retarded. To corroborate the observed phenomenon, experiments were conducted using both as-received and vacuum-annealed sheet specimens. It was verified that the observed phenomena originated from the released hydrogen in traps by metal dissolution under anodic polarization. KW - Energy Engineering and Power Technology KW - Condensed Matter Physics KW - Fuel Technology KW - Renewable Energy, Sustainability and the Environment PY - 2020 U6 - https://doi.org/10.1016/j.ijhydene.2019.11.218 SN - 1879-3487 VL - 45 IS - 4 SP - 3307 EP - 3315 PB - Elsevier BV CY - New York, NY AN - OPUS4-59322 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Liu, Xiangju A1 - Huang, Yanliang A1 - Li, Jianzheng A1 - Yang, Dan A1 - Xu, Yong A1 - Kunte, Hans-Jörg T1 - Effect of microbial hydrogen consumption on the hydrogen permeation behaviour of AISI 4135 steel under cathodic protection N2 - The feasibility of microbial hydrogen consumption to mitigate the hydrogen embrittlement (HE) under different cathodic potentials was evaluated using the Devanathan-Stachurski electrochemical test and the hydrogen permeation efficiency h. The hydrogen permeation efficiency h in the presence of strain GA-1 was lower than that in sterile medium. The cathodic potential inhibited the adherence of strain GA-1 to AISI 4135 steel surface, thereby reducing the hydrogen consumption of strain GA-1. The adherent GA-1 cells were capable of consuming ‘cathodic hydrogen’ and reducing the proportions of absorbed hydrogen, indicating that it is theoretically possible to control HE by hydrogen-consuming microbes. KW - Energy Engineering and Power Technology KW - Condensed Matter Physics KW - Fuel Technology KW - Renewable Energy, Sustainability and the Environment PY - 2020 U6 - https://doi.org/10.1016/j.ijhydene.2019.12.058 SN - 1879-3487 VL - 45 IS - 7 SP - 4054 EP - 4064 PB - Elsevier BV CY - New York, NY AN - OPUS4-59319 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schmidt, Wolfram A1 - Olonade, K. A. A1 - Mbugua, R. N. A1 - Lenz, F. J. A1 - Tchetgnia Ngassam, I. T1 - Bio-Based Rheology Modifiers for High Performance Concrete – Possible Modes of Actions and Case Study for Cassava Starch in West Africa N2 - Polymers that help tailoring rheological properties during the casting process have become inevitable constituents for all kinds of high-performance concrete technologies. Due to lacking industries, these typically crude-oil based admixtures are not readily available in many parts of the world, which limits the implementation of more sustainable high-performance construction technologies in these regions. Alternative polymers, which often demand for less processing, can be derived from local plant-based resources. The paper provides experimental data of flow tests of cement pastes with polysaccharides from Triumfetta pendrata A. Rich, acacia gum and cassava without and in the presence of polycarboxylate ether superplasticizer. The flow tests are amended by observations of the zeta potentials and the hydrodynamic diameters in the presence of and without calcium ions in the dispersion medium. The results show that in the presence of and without calcium ions all polysaccharides provide negative zeta potentials, yet, they affect flowability and thixotropy in different ways. Cassava starch, acacia gum, and the gum of Triumfetta pendrata A. Rich qualified well for robustness improvement, strong stiffening, and additive manufacturing, respectively. The reason for the different effects can be found in their average sizes and size distribution. Due to the promising results, a flow chart for local value chains is derived on the example of yet unused cassava wastes, which can be converted in parallel. T2 - 3rd International Conference on the Application of Superabsorbent Polymers CY - Skukuza, South Africa KW - Admixtures KW - Polysaccharides KW - Rheology KW - Thixotropy KW - Concrete PY - 2020 SN - 978-3-030-33341-6 SN - 978-3-030-33342-3 U6 - https://doi.org/10.1007/978-3-030-33342-3_17 SP - 158 EP - 166 PB - Springer AN - OPUS4-58404 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Carvello, J. M. F. A1 - Carvalho Fontes, W. A1 - de Azevedo, C. F. A1 - Brigolini, G. J. A1 - Schmidt, Wolfram A1 - Fiorotti Peixoto, R. A. T1 - Enhancing the eco-efficiency of concrete using engineered recycled mineral admixtures and recycled aggregates N2 - Non-conventional densely packed concrete mixtures are proposed and evaluated in this paper using engineered recycled mineral admixtures and recycled aggregates obtained from steel slag, quartz mining tailings, and quartzite mining tailings. High fines content sand-concretes containing coarser- and finer-than-cement recycled powders were designed to obtain blends with broader particle-size ranges and improved packing density. As a result, compressive strength up to 99 MPa, cement intensity up to 2.33 kg/m³/MPa, and consumption of recycled material up to 95 vol% were obtained. Compressive strengths up to 66 MPa and cement intensity up to 2.34 kg/m³/MPa were also obtained with the addition of coarse aggregates to such sand-concrete mixtures, with consumption of recycled material up to 96.5%. The results launch new insights on the role of recycled admixtures and aggregates on the mixture design of cement-based composites regarding efficiency improvement and technological performance. KW - Low-cement concrete KW - Recycled mineral admixture KW - Basic oxygen furnace slag KW - Quartzite mining tailing KW - Packing density PY - 2020 U6 - https://doi.org/10.1016/j.jclepro.2020.120530 VL - 257 SP - 1 EP - 12 PB - Elsevier AN - OPUS4-58401 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Carvello, J. M. F. A1 - Schmidt, Wolfram A1 - Kühne, Hans-Carsten A1 - Fiorotti Peixoto, R. A. T1 - Influence of high-charge and low-charge PCE-based superplasticizers on Portland cement pastes containing particle-size designed recycled mineral admixtures N2 - Design : and use of engineered recycled mineral admixtures obtained from industrial and mineral waste are promising strategies to increase the range of materials suitable for use in cement-based composites. In this work, Portland cement-blended pastes containing mineral admixtures designed for improving particle packing were evaluated in the presence of low- and high-charge polycarboxylate-based superplasticizers. The powders were obtained from basic oxygen furnace slag, iron ore tailings, quartz mining tailings, and quartzite mining tailings. The zeta-potentials of the particles were obtained via electrophoretic mobility. The flow properties were evaluated by rheological tests performed in a Couette type rheometer. The hydration kinetics was evaluated by isothermal calorimetry and an adapted method based on the Vicat needle test. The high-charge PCE and the finer mineral admixtures produced more stable blends. Coarser mineral admixtures led to increased flowability and delayed hydration compared to finer ones. Steel slag powders presented the most significant plasticizer effects, but also the largest setting delays and segregation tendency. Quartz-rich superfines reduced the setting delays caused by the superplasticizers. In summary, both superplasticizers were effective in improving flow properties, but the high-charge PCE was effective in preventing segregation in pastes containing mineral admixtures coarser and heavier than cement. KW - Engineered recycled mineral admixtures KW - Rheology KW - PCE-Based superplasticizer KW - Steel slag KW - Mining tailing PY - 2020 U6 - https://doi.org/10.1016/j.jobe.2020.101515 VL - 32 SP - 1 EP - 16 PB - Elsevier AN - OPUS4-58395 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pirker, F. A1 - Toth, I. A1 - Cihak-Bayr, U. A1 - Grundtner, R. A1 - Vernes, A. A1 - Benedicto, J. A1 - Spaltmann, Dirk A1 - Gradt, Thomas A1 - Alberdi, A. A1 - Alonso, I. A1 - Bayón, R. A1 - Igartua, A. A1 - García, Á. A1 - Pagano, F. A1 - Bravo, I. A1 - Kogia, M. A1 - Dykeman, D. A1 - Liedtke, S. A1 - Minami, I. A1 - Nyberg, E. A1 - Soivio, K. A1 - Ronkainen, H. A1 - Majaniemi, S. A1 - Heino, V. A1 - Gkagkas, K. A1 - Mont, L. A1 - Amigorena, I. T1 - Tribological characterisation services for materials - i-TRIBOMAT N2 - Um den Entwicklungsprozess von neuen Komponenten zu beschleunigen, ist die Vorrausage der Eigenschaften der eingesetzten Werkstoffe im Betrieb der Komponenten von enormer Bedeutung. Um neue Werkstoffe hinsichtlich Ihrer Performance (in einer Komponente) bewerten zu können, ist deshalb die Entwicklung neuer innovativer Methoden notwendig. Diese Methoden können auch unter dem Begriff „lab-to-field“ oder „materials“ – up-scaling zusammengefasst werden. D. h. Werkstoffe werden im Labor charakterisiert, und deren Eigenschaften mittels z.B. Simulation auf die Komponentenperformance hochskaliert (upscaling). i-TRIBOMAT ist ein EU gefördertes Projekt (H2020, GA Nr. 814494) mit dem Ziel ein Open Innovation Test Bed für tribologische Werkstoffcharakterisierung aufzubauen und entsprechende Services von der tribologischen Charakterisierung neuer Werkstoffe bis hin zu Simulationsmodellen zur Vorrausage der Perfomance von Komponenten der Industrie anzubieten. Durch die Bündelung von Knowhow und Infrastruktur zu Charakterisierung sowie den Aufbau einer digitalen Plattform, wird i-TRIBOMAT das weltgrößte Open Innovation Test Bed für tribologische Werkstoffcharakterisierung. N2 - The prediction of the properties of the materials used in the operation of components is of enormous importance, in order to accelerate the development process of new components. To evaluate new materials in terms of their performance (in a component), the development of new innovative methods is necessary. These methods can also be summarized under the term lab-to-field or materials – upscaling, meaning materials being characterised in a laboratory and their properties being upscaled to the component performance by means of e.g. simulation. i-TRIBOMAT is a EU funded project (H2020, GA Nr. 814494) aiming at building an Open Innovation Test Bed for tribological material characterization and offering corresponding services from tribological characterization of new materials to simulation models for predicting the performance of industrial components. By bundling the infrastructure, know-how for characterization and building a digital platform, i-TRIBOMAT becomes the world’s largest open innovation test bed for tribological material characterization. T2 - 22nd International Colloquium Tribology CY - Esslingen, Germany DA - 28.01.2020 KW - Tribologie KW - Lab-to-field up-scaling KW - Werkstoffdatenbank KW - Geteilte Infrastruktur KW - Tribo-Analytik KW - Intelligente tribologische Werkstoffcharakterisierung KW - Lab-to-field upscaling KW - Tribology KW - Intelligent tribological material characterization KW - Materials database KW - Shared infrastruture KW - Tribo-analytics PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-576762 SN - 0724-3472 SN - 2941-0908 VL - 67 IS - 5-6 SP - 35 EP - 50 PB - Expert CY - Tübingen AN - OPUS4-57676 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Rethmeier, Michael A1 - Biegler, M. A1 - Javaheri, E. T1 - Qualifizierung der instrumentierten Eindringprüfung zur Kennwertermittlung für hochfeste Stähle mit Schweißungen N2 - Der Einsatz von hochfesten Stählen im Karosseriebereich des Automobilbaus hat während der letzten Jahre stark zugenommen. Hierzu zählen Dual- und Komplexphasenstähle, welche durch Kombination unterschiedlicher Gefügebestandteile auch deren Vorteile kombinieren, sowie TRIP (TRansformation Induced Plasticity) und Mangan-Bor Stähle, welche sehr gute Umformeigenschaften mit hohen Festigkeiten durch Martensitbildung bei der Umformung kombinieren. TWIP (Twinning Induced Plasticity) Stähle erreichen ähnliche Effekte durch forcierte Zwillingsbildung. Die Ursachen für den Einsatz dieser Stähle liegen in dem Potential dieser Materialien zur Gewichts- und Kostenreduzierung, bei gleichzeitiger Erhöhung der Fahrgastsicherheit. Auf Grund der prinzipiell gegebenen Schweißeignung dieser Stähle, werden die klassischen Fügeverfahren im Karosseriebau wie das kostengünstige und effektive Widerstandspunktschweißen, das Metall-Schutzgas (MSG)-Schweißen oder das Laserschweißen angewendet. Allerdings treten teilweise Herausforderungen, beispielsweise durch Gefügeveränderungen in den Fügestellen auf, die zu ungewollten Aufhärtungen oder Erweichungen führen. In diesem Projekt wird ein Verfahren entwickelt, mit welchem die lokalen Werkstoffeigenschaften von im Automobilbau typischen Werkstoffen und deren Fügestellen bestimmt werden können. Relevante Kennwerte sind in erster Linie das SpannungsDehnungs-Verhalten der verschiedenen Zonen einer Schweißverbindung; relevante Zonen wiederum sind neben dem Grundwerkstoff die Wärmeeinflusszone und das Schweißgut. Zu diesem Zweck wird das Verfahren der instrumentierten Eindringprüfung für den Einsatz bei hochfesten Stählen weiterentwickelt. Zunächst werden hierzu Zugversuche an einfachen Grundwerkstoffgeometrien durchgeführt. Im Anschluss wird die optische Dehnungsfeldmessung an stark taillierten, geschweißten Zugversuchsproben durchgeführt. Die Taillierung dient dem Zweck, die WEZ auch mittels WPS über den gesamten Querschnitt der Probe erzeugen zu können, bzw. im Versuch auch Dehnungen in den relevanten Bereichen herbeizuführen. Das im Projekt angewendete Auswerteverfahren, welches auf nichtlinearen Regressionsmodellen in Form von künstlichen, neuronalen Netzwerken beruht, ermöglicht die Vorhersage des Festigkeitsverhaltens des Werkstoffes anhand der gemessenen Krafteindringwegdaten. KW - Eindringprüfung KW - Hochfester Stahl KW - Prüfverfahren PY - 2020 SN - 978-3-946885-98-6 SP - 1 EP - 164 PB - Forschungsvereinigung Stahlanwendungen AN - OPUS4-57322 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Neuhold, S. A1 - Algermissen, D. A1 - Drissen, P. A1 - Adamczyk, Burkart A1 - Presoly, P. A1 - Sedlazeck, K. P. A1 - Schenk, J. A1 - Raith, J. G. A1 - Pomberger, R. A1 - Vollprecht, D. T1 - Tailoring the FeO/SiO2 Ratio in Electric Arc Furnace Slags to Minimize the Leaching of Vanadium and Chromium N2 - Based on recently published research on leaching control mechanisms in electric arc furnace (EAF) slags, it is assumed that a FeO/SiO2 ratio of around one leads to low leached V and Cr concentrations. This ratio influences the mineral phase composition of the slag toward higher amounts of spinel and a lower solubility of calcium silicate phases by suppressing the formation of magnesiowuestite and highly soluble calcium silicate phases. To evaluate this hypothesis, laboratory and scaled up tests in an EAF pilot plant were performed on slag samples characterized by elevated V and Cr leaching and a high FeO/SiO2 ratio. Prior to the melting experiments, the optimum FeO/SiO2 ratio was calculated via FactSageTM. In the melting experiments, the ratio was adjusted by adding quartz sand, which also decreased the basicity (CaO/SiO2) of the slag. As a reference, remelting experiments without quartz sand addition were conducted and additionally, the influence of the cooling rate of the slag was examined. The remelted (without quartz sand) and the remelted modified slags (with quartz sand) were analyzed chemically and mineralogically and the leaching behavior was investigated. The modification of the slags yielded a minimized release of V and Cr, supporting the hypothesis that the FeO/SiO2 ratio influences the mineralogy and the leaching behavior. KW - Electric arc furnace (EAF) slags KW - FactSageTM calculations KW - Leaching control mechanisms KW - Melting experiments PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-571517 VL - 10 IS - 7 SP - 1 EP - 18 PB - MDPI AN - OPUS4-57151 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schade, U. A1 - Puskar, L. A1 - Ritter, E. A1 - Beckmann, Jörg T1 - Etalon effects in THz film measurements N2 - Etalon features in transmittance spectra of films arise due to the coherent superposition of waves caused by reflections multiple times at the inner film boundaries. The fringe maxima occur at i𝜆 = 2nd cos 𝜑 with i - being an integer, 𝜆 - the wavelength, d - the film thickness, 𝜑 - the angle of incidence in respect to the film normal and n - the refractive index of the film. It is obvious that such features can hinder the interpretation of absorption bands when fringe amplitude and period are in the same range as the expected bands. This poster discusses the suitability of two optical methods for the THz spectral range applied to Fourier Transform Spectroscopy. T2 - 2020 45th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) CY - Buffalo, NY, USA DA - 08.11.2020 KW - THz radiation KW - Total transmittance reflection technique PY - 2020 AN - OPUS4-56945 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -