TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Atomic force microscope study of friction at the submicron-scale during tribotests with self-mated steel N2 - Friction at the microscale during reciprocal sliding tribotests was studied for the first time with self-mated steel (100Cr6/AISI 52100) taking advantage of an atomic force microscope (AFM). To this aim, microsized steel particles were glued to the AFM-cantilever and employed as colloidal tips to perform tribotests on a steel disc. The torsion of the cantilever, which correlates with the friction force, was measured during the tests. Few tests with the same load did not yield any wear and show that the load and adhesion contributions to friction stay constant when the shape of the test particle does not change. Most of the presented tribotests engendered wear. For those tests, the increase of friction during the tribotests was attributed to the emerging plowing contribution. Furthermore, analysis of both torsion and local slope gives information on the creation of wear particles and their influence on friction. KW - Friction KW - Microtribology KW - Sliding KW - Wear PY - 2022 U6 - https://doi.org/10.1115/1.4054251 VL - 144 IS - 10 SP - 1 EP - 9 PB - ASME AN - OPUS4-54839 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine T1 - Sliding behaviour of polymer materials in hydrogen N2 - This lecture deals with the sliding behaviour of polymer materials in hydrogen environment. After a short introduction of the hydrogen activities at BAM, the tribological performances of polymer materials in gaseous hydrogen are presented and compared with air and vacuum environment. The second part focusses on the influence of the counterface materials in hydrogen. Finally, the last section is dedicated to experiments liquid hydrogen. T2 - Invited lecture, TRIBOS+ program at Lulea University of Technology CY - Lulea, Sweden DA - 30.06.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-53708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine T1 - On the tribological behaviour of polymer composites in vacuum N2 - This lecture deals with the sliding behaviour of polymer composites in vacuum environment. At first, the effect of the polymer matrix and solid lubricants such as graphite and MoS2 are presented. The second part focusses on the influence of the residual pressure with experimental results obtained in high and ultrahigh vacuum. T2 - Invited lecture, TRIBOS+ program at Lulea University of Technology CY - Lulea, Sweden DA - 29.06.2021 KW - Polymers KW - Vacuum KW - Friction KW - Wear PY - 2021 AN - OPUS4-53710 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine A1 - Gradt, Thomas T1 - Benchmarking of polymer materials for tribological applications in hydrogen N2 - The focus of this study is to evaluate of hydrogen on the friction and wear behavior of a wide range of polymer materials. Thereby, the tribological performance of filled and unfilled polymers from different suppliers were compared at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -253°C (LH2). T2 - 62. Tribologie-Fachtagung der Gesellschaft für Tribologie e. V. CY - Online meeting DA - 27.09.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-53700 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine A1 - Gradt, Thomas T1 - Tribology of polymeric materials in gaseous and liquid hydrogen N2 - This presentation gives an overview of the tribological behaviour of polymeric materials in gaseous and luquid hydrogen. T2 - HYDROGENIUS-BAM Joint Hydrogen Symposium CY - Online meeting DA - 06.07.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-53701 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine T1 - Friction and wear of polymer materials at cryogenic temperatures N2 - This lecture deals with the friction and wear of polymeric materials at cryogenic temperatures. The first part is dedicated to the low temperature properties of polymers and cryogenic environment as well as an introduction to cryotribology and friction models. The second part presents some experimental results, focusing on the effect of polymer composition, cryogenic media and stick-slip behaviour. T2 - Invited lecture, TRIBOS+ program at Lulea University of Technology CY - Lulea, Sweden DA - 29.06.2021 KW - Polymers KW - Cryogenic temperature KW - Friction KW - Wear PY - 2021 AN - OPUS4-53706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cappella, Brunero A1 - Reichelt, Manuel T1 - Origin of lognormal distribution of wear coefficient values N2 - Wear test results exhibit often large scattering. Hence, the study of spreading of experimental results requires big datasets. In various studies, wear coefficients were found to have lognormal distributions. Therefore, it was supposed that the wear coefficient is affected by two normally distributed variables, which combine through a product. In the present study, we demonstrate that a lognormal distribution may arise from a nonconstant wear coefficient, too, i.e., when a system does not follow Archard’s law. KW - Wear KW - Archard's law KW - Statistical distributions KW - Spreading PY - 2021 U6 - https://doi.org/10.1016/j.triboint.2021.107207 SN - 0301-679X VL - 164 PB - Elsevier Ltd. AN - OPUS4-53100 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reichelt, Manuel A1 - Cappella, Brunero T1 - Large scale multi-parameter analysis of wear of self-mated 100Cr6 steel - A study of the validity of Archard's law N2 - Considerable scattering of experimental wear results affects seriously the evaluation of repeatability and reproducibility of tribological measurements and hampers detecting, studying, and verifying tribological laws. An accurate characterization of the statistics of results, the detection of the influence of operating parameters, and the verification of equations describing tribological phenomena can be achieved only through the analysis of large datasets with wide variation of parameters. Taking advantage of more than 400 experiments performed with the same material pairing under the same conditions on four different tribometers, the repeatability and reproducibility of volumetric wear measurements has been evaluated using Welch's test. By testing Archard's law over seven orders of magnitude of sFN, it was found that this law is not universally valid and that, under certain conditions, the wear coefficient depends on sFN itself. KW - Wear KW - Archard's law KW - 100Cr6 steel KW - Scattering PY - 2021 U6 - https://doi.org/10.1016/j.triboint.2021.106945 VL - 159 SP - 6945 PB - Elsevier Ltd. AN - OPUS4-52244 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Theiler, Géraldine A1 - Gradt, Thomas T1 - Benchmarking of polymer materials for tribological applications in hydrogen N2 - The focus of this study is to evaluate the influence of hydrogen on the friction and wear behavior of a wide range of polymer materials. Thereby, the tribological performance of filled und unfilled polymers from different suppliers were compared at room temperature in air and hydrogen gas (H2) as well as in liquid hydrogen at -235°C (LH2). T2 - 23rd International Conference on Wear of Materials CY - Online meeting DA - 26.04.2021 KW - Polymers KW - Hydrogen KW - Friction KW - Wear PY - 2021 AN - OPUS4-52651 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schirdewahn, S. A1 - Spranger, Felix A1 - Hilgenberg, Kai A1 - Merklein, M. T1 - Investigation of the thermal and tribological performance of localized laser dispersed tool surfaces under hot stamping conditions N2 - In the automotive industry, hot stamping has been established as a key technology for manufacturing safety-relevant car body components with high strength-to-weight ratio. However, hot stamping tools are stressed by cyclic thermo-mechanical loads, which leads to severe wear and high friction during the forming operation. Consequently, the quality of the parts, the durability of the tools and the efficiency of the process are negatively affected. Within the scope of this work, a promising approach named laser implantation process has been investigated for improving the tribological behavior of hot stamping tools. This technique enables the fabrication of highly wear resistant, separated and elevated micro-features by embedding hard ceramic particles into the tool via pulsed laser radiation. Hence, highly stressed tool areas can be modified, which influences the thermal and tribological interactions at the blank-die interface. To clarify these cause-effect relations, numerical simulations, quenching tests as well as tribological investigations have been conducted. In this context, laser-implanted tools reveal a significantly improved tribological performance while offering the possibility to adjust the thermal properties within hot stamping. Based on these results, a tailored tool modification can be pursued in future research work, in order to enhance the effectiveness of hot stamping tooling systems. KW - Hot stamping KW - Laser Implantation KW - Surface structuring KW - Wear KW - Friction PY - 2021 U6 - https://doi.org/10.1016/j.wear.2021.203694 VL - 476 SP - 1 EP - 11 PB - Elsevier B.V. AN - OPUS4-52988 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -