TY - JOUR A1 - Österle, Werner A1 - Dörfel, Ilona A1 - Wollenschläger, Nicole A1 - Gradt, Thomas A1 - Wolter, Christian A1 - Reinstädt, Philipp A1 - Zeigmeister, U. A1 - Dmitriev, A. I. A1 - Nikonov, A. Y. T1 - Potential of different nickel coatings for optimizing the sliding behavior of electrical connectors JF - Tribology International N2 - The potential of several nickel coatings was investigated by reciprocating sliding tests against copper thus simulating the plug-socket system of an electrical connector. KW - Electrical connectors KW - Electro-plated nickel coatings KW - Electroless Ni-P KW - Cold-welding KW - Tribooxidation PY - 2018 DO - https://doi.org/10.1016/j.triboint.2018.01.006 SN - 0301-679X SN - 1879-2464 VL - 120 SP - 491 EP - 501 PB - Elsevier Ltd. AN - OPUS4-44468 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 - Österle, Werner A1 - Giovannozzi, A. A1 - Gradt, Thomas A1 - Häusler, Ines A1 - Rossi, A. A1 - Wetzel, B. A1 - Zhang, G. A1 - Dmitriev, A.I. T1 - Exploring the potential of Raman spectroscopy for the identification of silicone oil residue and wear scar characterization for the assessment of tribofilm functionality JF - Tribology International N2 - We applied a combination of Raman spectroscopy (RS) and cross-sectional transmission electron microscopy (X-TEM) to identify silicone oil residues and tribofilms at steel disc surfaces after tribological testing. Neither chemical cleaning nor mechanical removal of a 50 µm thick surface layer produced a surface without any silicone residue. Nevertheless, long-term tribological properties are not affected due to silicone degradation which has been proved by Raman spectroscopy. Excellent anti-wear and anti-friction properties of a nanocomposite at severe stressing conditions correlated with the formation of a silica-based tribofilm containing amorphous and graphite-like carbon nanoparticles. Since reliable carbon quantification by analytical TEM is difficult, RS is a useful complementary method for carbon identification at wear scars. KW - Raman spectroscopy KW - Cross-sectional TEM KW - Silicone oil residue KW - Tribofilm PY - 2015 DO - https://doi.org/10.1016/j.triboint.2015.04.046 SN - 0301-679X VL - 90 SP - 481 EP - 490 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-33421 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Österle, Werner A1 - Deutsch, Cornelius A1 - Gradt, Thomas A1 - Orts Gil, Guillermo A1 - Schneider, Thomas A1 - Dmitriev, A.I. T1 - Tribological screening tests for the selection of raw materials for automotive brake pad formulations JF - Tribology International N2 - A modified pin-on-disc test was applied to determine tribological properties of typical brake pad constituents. Ball-milling of these ingredients together with iron oxide and graphite provided model materials displaying the main features of real third bodies. Solid lubricants like graphite affected the friction and wear behaviour of Fe3O4 powders considerably whereas further addition of hard nanoparticles induced only minor effects. This was corroborated by comparison with modelling results. MoS2 played a dual role. Depending on special conditions, this ingredient either reduced or increased friction. The latter could be explained, after nanoscopic characterization, by oxidation and destruction of the wear-protecting tribofilm. KW - Brake pad formulation KW - Raw materials KW - Third body KW - Pin-on-disc test PY - 2014 DO - https://doi.org/10.1016/j.triboint.2014.01.017 SN - 0301-679X VL - 73 SP - 148 EP - 155 PB - Butterworth-Heinemann CY - Oxford AN - OPUS4-30221 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Theiler, Geraldine A1 - Gradt, Thomas A1 - Österle, Werner A1 - Brückner, A. A1 - Weihnacht, V. T1 - Friction and endurance of MoS2/ta-C coatings produced by laser arc deposition JF - Wear N2 - The tribological behaviour of MoS2/ta-C double layer coatings deposited by Laser-Arc technology was investigated in vacuum and air. In vacuum environment, the friction coefficient against steel balls varies between 0.005 and 0.02 depending on the contact pressure. At high contact pressures, the friction coefficient is as low as 0.005 and the life time between 340,000 and 500,000 cycles. Furthermore, it is shown that a ta-C base layer improves the performance of MoS2 coating. Surface analyses were performed before and after the tribological tests by means of SEM, EDX, XRD, and TEM. They show that in the top layer beneath the sliding surface crystallization of the initially quasi-amorphous MoS2 took place. TEM images also verified an orientation of the basal MoS2-lattice planes parallel to the surface. KW - MoS2 coatings KW - Ta-C KW - Vacuum KW - Laser arc deposition PY - 2013 DO - https://doi.org/10.1016/j.wear.2012.10.007 SN - 0043-1648 VL - 297 IS - 1-2 SP - 791 EP - 801 PB - Elsevier CY - Amsterdam AN - OPUS4-27114 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -