TY - THES A1 - Scholz, Christian T1 - Low friction slip-rolling contacts - Influences of alternative steels, high performance thin film coatings and lubricants N2 - Due to the growing environmental awareness worldwide, containment provisions for CO2 emissions in mobility systems and increasing performance requirements the demands on mechanical systems and their materials continuously rise. These high demands require the implementation of new technical approaches, for example of light-weight strategies in automotive powertrains, and directly raise questions about the suitability of the most promising technical solution. Two basic parameters, the surface hardness of the tooth flanks and the core fatigue strength of the tooth root, illustrate exemplarily increasing demands on material grades used for gear wheels in automotive powertrains. In addition to light-weight strategies, a reduction in friction and an increase of the fatigue lifetime are two other major development directions to strive the mentioned targets. It is clear that any kind of solution must show an equal application profile, preferably an improvement, compared to the state-of- the-art solutions. For tribological systems, the following paths may offer lower friction and higher load carrying capabilities: 1. Alternative base oils and additives (such as esters, polyglycols), 2. Thin film coatings (e.g. DLC) and/or 3. Novel steel metallurgies. In previous investigations on the slip-rolling resistance of thin film coatings (a-C, ta-C, Zr(C,N)) the substrates were mainly made of the bearing steels 100Cr6H and Cronidur 30. Applying contact pressures of up to P0max = 2.9 GPa (FN = 2,000 N), the samples were tested up to 10 million load cycles in endurance tests. The aim of the present work is to broaden the research by varying the input parameters. Newly developed engine oil mixtures, high performance thin film coatings and alternative steel solutions are intensively investigated in highly stressed slip-rolling contacts at lubricant temperatures of 120°C. Specifically, in using new steel metallurgies, i.e. the high toughness and high strength steels V300 and NC310YW (Aubert & Duval) as well as CSS-42L (Latrobe Specialty Steel Company), in combination with thin film coatings, even if they compete in the uncoated state, the Hertzian contact pressures could be increased up to P0max = 4.2 GPa (FN = 5,000 N) without any surface failures of coating or substrate. It was shown that selected thin film coatings can minimize the wear rates down to nearly ‘zero-wear’ in highly stressed contacts [Woy08] [Woy11]. In addition, the studies revealed not only the high potential in slip-rolling resistance, but also a possible friction reduction down to 0.047 by use of uncoated steels with increased toughness. Compared to steels like 100Cr6H and Cronidur 30 this means a reduction in friction of approximately 40% under identical testing conditions. Different test series with newly developed base oil-additive formulations were investigated with specific emphasis on the frictional behavior of selected bio-no-tox EP/AW additives and friction modifiers. Additional influencing factors like the structural and surface conditions of the steels/coatings before and after the tests were analyzed by means of REM, EDX, XRD and TEM. T3 - BAM Dissertationsreihe - 96 KW - hoch zähe Si-Stähle KW - geringe Reibung KW - DLC KW - Zr (C, N) PY - 2013 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-624 SN - 978-3-9815134-2-7 SN - 1613-4249 VL - 96 SP - 1 EP - 153 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-62 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gradt, Thomas A1 - Theiler, Géraldine T1 - Materials for tribosystems in hydrogen technology N2 - In this presentation tribological investigations on steels, polymers and coatings in gaseous and liquid hydrogen are shown. For steels the results of show that although martensitic steel may suffer from hydrogen embrittlement, application e.g. in roller bearings is possible. On the other hand, martensitic transformation of austenitic steels may cause problems in the application of these materials. Furthermore, the tribological performance of polymer composites with and without solid lubricant fillers in gaseous and liquid hydrogen was investigated. In particular, PEEK- and PTFE-matrix compounds showed low friction and sufficient low wear under these conditions. Among the solid lubricants, carbon-based materials are appropriate for hydrogen applications. Several variants of DLC and ta-C materials were tested. Beside the results for hydrogen, also a comparison with CH4-environment is shown. T2 - ÖTG-Symposium 2021 CY - Online meeting DA - 18.11.2021 KW - Hydrogen environment KW - Liquid hydrogen KW - Austenitic stainless steels KW - Polymer composites KW - DLC PY - 2021 AN - OPUS4-53793 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jayachandran, Ashokraj A1 - Wäsche, Rolf T1 - Sliding wear behavior of DLC under lubricated conditions at elevated temperatures N2 - The influence of temperature and counter body material on the tribological properties of a-C:H coatings deposited on Cronidur 30 steel has been investigated in a lubricated ball on disk contact siutation with an oil temperature up to 250°C. The results show, that the wear volumes of the system increase exponentially with increasing temperature. T2 - 44th Leeds-Lyon Symposium on Tribology 2017 CY - Lyon, France DA - 03.09.2017 KW - Wear volume KW - DLC KW - Coefficient of friction PY - 2017 AN - OPUS4-42183 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wäsche, Rolf A1 - Ehrke, R. A1 - Kramer, R. A1 - Jayachandran, A. R. A1 - Brandt, G. T1 - Influence of temperature on tribological behaviour of DLC coatings under lubricated conditions up to 250°C T2 - Proceedings of Asia International Conference on Tribology N2 - In the present work it was shown that there is an influence of temperature and counter body material on the tribological properties of a-C:H coatings deposited on Cronidur 30 steel in a lubricated ball on disk contact situation. T2 - ASIATRIB 2018 CY - Kuching, Sarawak, Malaysia DA - 17.09.2018 KW - DLC KW - Temperature KW - Lubricated sliding PY - 2018 SP - 253 EP - 254 AN - OPUS4-46213 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -