TY - JOUR A1 - Meine, Kerstin A1 - Schneider, Thomas A1 - Spaltmann, Dirk A1 - Santner, Erich T1 - The influence of roughness on friction - Part I: The influence of a single step KW - Tribology KW - Roughness KW - Friction force KW - Elastic deformation PY - 2002 SN - 0043-1648 VL - 253 SP - 725 EP - 732 PB - Elsevier CY - Amsterdam AN - OPUS4-1580 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meine, Kerstin A1 - Schneider, Thomas A1 - Spaltmann, Dirk A1 - Santner, Erich T1 - The influence of roughness on friction - Part II: The influence of multiple steps KW - Tribology KW - Roughness KW - Friction force KW - Elastic deformation PY - 2002 SN - 0043-1648 VL - 253 SP - 733 EP - 738 PB - Elsevier CY - Amsterdam AN - OPUS4-1581 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Löhr, Manuel A1 - Spaltmann, Dirk A1 - Binkowski, Sigrid A1 - Santner, Erich A1 - Woydt, Mathias T1 - In situ Acoustic Emission for wear life detection of DLC coatings during slip-rolling friction N2 - Different diamond-like carbon (DLC) coatings on a steel substrate (100Cr6) were tested under slip-rolling friction conditions against uncoated counter bodies of the same steel. The initial maximum Hertzian pressure was varied in a range of P0 = 1.5–2.3 GPa. The friction tests were carried out under dry conditions and with an unadditivated paraffin oil as lubricant. It could be shown that the thickness of the coatings affects the respective wear life. Further, a very important factor for the wear life of a coating under lubricated slip-rolling conditions is the roughness of the surface of the respective counterbody. The wear life tests were monitored by recording in situ the Acoustic Emission (AE) signals. Some causes for a high AE activity could be identified. KW - Wear life KW - Slip-rolling friction KW - Diamond-like carbon (DLC) KW - Acousitc Emission KW - Lubircation KW - Roughness PY - 2006 U6 - https://doi.org/10.1016/j.wear.2005.03.009 SN - 0043-1648 VL - 260 IS - 4-5 SP - 469 EP - 478 PB - Elsevier CY - Amsterdam AN - OPUS4-12064 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Spaltmann, Dirk A1 - Löhr, Manuel A1 - Binkowski, Sigrid A1 - Kelling, Norbert A1 - Soltwedel, Rocco A1 - Woydt, Mathias A1 - Santner, Erich T1 - Schäden wälzbeanspruchter DLC-Schichten auf Stahlsubstraten unterschiedlicher Härte N2 - Paraffinöl geschmierte Wälztests wurden an extrem harten Diamantschichten auf hartem SSiC Substrat, unterschiedlichen, harten DLC-Schichten auf 100Cr6 Substraten (HRC60) sowie ausgewählten DLC-Schichten auf ungehärtetem Stahl (HRC 20) durchgeführt. Die Wälztests wurden in einem Zweischeibentribometer vom Typ Amsler bei einer anfänglichen, maximalen Flächenpressung nach Hertz von P0=2,3 GPa ausgeführt. Als Abbruchkriterium für die Tests wurde das Erreichen von n=1.000.000 Überrollungen (Langzeittests n=10.000.000 Überrollungen) oder das Auftreten einer Schädigung mit einer zusammenhängenden Fläche von A>1 mm2 festgelegt. Die Wälztests zeigten, dass das harte SSiC Substrat zwar eine stützende Wirkung auf die Diamantschicht hat, diese aber aufgrund von Rissen im Substrat versagte. Ferner gibt es wenigstens zwei DLC-Schichten, die, aufgebracht auf 100Cr6 Scheiben (HRC60), den Wälztests bis n=10.000.000 Überrollungen ohne nennenswerte Schäden widerstanden. Diese Schichten passten sich auch den Verformungen des weichen, stickstofflegierten Stahls (HRC20) an, ohne das es zu größeren Abplatzungen kam (A>1 mm2). KW - Slip-rolling KW - Lubrication KW - Hardness KW - DLC KW - Steel KW - Wälzen KW - Schmierung KW - Härte KW - DLC KW - Stahl PY - 2005 U6 - https://doi.org/10.1002/mawe.200400850 SN - 0933-5137 SN - 1521-4052 VL - 36 IS - 2 SP - 62 EP - 68 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-7209 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Meine, Kerstin A1 - Kloß, K. A1 - Schneider, Thomas A1 - Spaltmann, Dirk T1 - The influence of surface roughness on the adhesion force N2 - Adhesion measurements are presented which were carried out with an atomic force microscope between polymer balls attached to a cantilever and a silicon wafer under ultra high vacuum conditions. In using a silicon surface with a defined structure a correlation between adhesion force and contact area was found. This correlation could partly be explained by the Johnson-Kendall-Roberts model, if a change of the surface energy is assumed as a result of the structuring. For a constant geometric contact area an additional structuring leads to a decrease of the adhesion force. T2 - 10th European Conference on Applications of Surface and Interface Analysis (ECASIA '03) CY - Berlin DA - 2003-10-05 KW - Roughness KW - Adhesion KW - AFM KW - UHV KW - JKR model KW - Surface energy PY - 2004 U6 - https://doi.org/10.1002/sia.1738 SN - 0142-2421 SN - 1096-9918 VL - 36 IS - 8 SP - 694 EP - 697 PB - Wiley CY - Chichester AN - OPUS4-4708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Klaffke, Dieter A1 - Santner, Erich A1 - Spaltmann, Dirk A1 - Woydt, Mathias T1 - Influences on the tribological behaviour of slip-rolling DLC-coatings N2 - Diamond like carbon (DLC)-coatings are applied very successfully on computer discs. Sliding friction tests confirm their high performance as dry lubricants with friction coefficients (COFs) below 0.1. In contrast to sliding tests, until very recently most of the DLC-coatings failed in slip-rolling test after fewer cycles than uncoated samples. However, present tests with DLC-coatings of seven different suppliers show a more promising tribological behaviour under slip-rolling conditions. The DLC-coatings were deposited onto steel 100Cr6, HRC 60, with a thickness of 2–3 ?m. The counter bodies were uncoated, grinded or polished 100Cr6 discs with 30 mm radius of curvature. The tests were performed on a twin disc testing rig (Amsler type) with paraffin oil under boundary/mixed lubrication and rolling with 10% slip. The initial, average Hertzian contact pressure was adjusted to Pm = 1.0, 1.25, and 1.5 GPa. The failure criterion was defined as the occurrence of a single damaged area larger than 1 mm2, which was controlled by optical microscopy (OM). An acoustic emission (AE) measurement system was installed as an additional online control for coating failure. The stressed coatings and the chipping areas were analyzed by OM, SEM, EDX, AFM and Raman spectroscopy. Until now, the results reveal that a large scatter in lifetime of coatings occurs not only between samples of different coaters but also between the samples of one single batch. The highest lifetime reached by a DLC-coating under these testing conditions is 10 × 106 cycles. That is the highest life time for a coating tested under the testing conditions above in our laboratory so far. The following factors were identified to influence the life time of the coatings: coating thickness, interlayer type, topography of the coatings, counter body roughness and mechanical properties. But the most important factor determining the life time of the coatings is that the coating process does produce homogenous layers free of faults. KW - DLC-coatings KW - Slip-rolling KW - Life time KW - Acoustic emission PY - 2005 U6 - https://doi.org/10.1016/j.wear.2005.01.008 SN - 0043-1648 VL - 259 SP - 752 EP - 758 PB - Elsevier CY - Amsterdam AN - OPUS4-7557 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manier, Charles-Alix A1 - Spaltmann, Dirk A1 - Theiler, Geraldine A1 - Woydt, Mathias T1 - Carboneous coatings by rolling with 10% slip under mixed/boundary lubrication and high initial Hertzian contact pressures N2 - Costs reduction is one of the major objectives in mechanical applications with a parallel increase of the power output. Another driver represents new environmental standards and their increasing restrictions in the automotive industry leading to the question, if materials based concepts may substitute harmful EP/AW additives in lubricants. This paper presents the slip-rolling resistance of different DLC/THC coatings on steel substrates with a definite slip rate of 10%. Industrial DLC coatings of ta-C and a-C:H types from various manufacturers were deposited on steels SAE 52100 and AMS 5898 to compile the slip-rolling resistance under initial average Hertzian contact pressures between 1.5 GPa and 2 GPa. The tests were carried out on Amsler-type twin disc tribometer under the regime of mixed/boundary lubrication in unadditivated paraffinic oil (ISO VG 46) and a factory fill engine oil. The spherical steel sample was uncoated and the cylindrical coated with DLC. Some coatings achieved 10 million cycles without any damage under a maximal Hertzian contact pressure Pmax well over 2.25 GPa, thus exceeding FZG 12. KW - DLC KW - Rolling KW - Mixed/boundary lubrication KW - Hertzian pressure PY - 2008 U6 - https://doi.org/10.1016/j.diamond.2008.01.066 SN - 0925-9635 VL - 17 IS - 7-10 SP - 1751 EP - 1754 PB - Elsevier CY - New York, NY AN - OPUS4-17816 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Spaltmann, Dirk A1 - Hartelt, Manfred A1 - Woydt, Mathias T1 - Triboactive materials for dry reciprocating sliding motion at ultra-high frequency N2 - High-power piezo-electric motors with power densities of 1.4 kW/kg display a potential for substituting hydraulic actuators. For this application, two novel tribometers of the same type have been designed using commercially available components for sliding motion at 40 kHz with amplitudes between 2.5 µm and 5 µm. The tribometers are equipped with means to measure amplitude, frequency, power required to keep the samples in motion and load applied. The effective motion between the two contacting bodies is monitored in each of the tribometers. These data are used to evaluate the coefficient of friction. The wear rate was determined after the tests. The set-ups were tested using well-known 100Cr6H (AISI 52100) samples before investigating novel, non-commercial substrates such as AlFeCrTi-alloys and tungsten carbide-based coatings as well as Magnéli-type coatings (Tin-2Cr2O2n-1 and TinO2n-1). This paper presents the principle of the ultra-high frequency tribometers and first tribological quantities of materials and coatings tested up to and above 1011 cycles. Very low wear rates in the range 10-8 mm³/Nm down to 10-10 mm³/Nm were determined under dry oscillation in air. KW - Frequency KW - Tribometer KW - Sliding friction KW - Wear KW - Triboactive materials KW - Magnéli-type phases KW - Aluminium alloy KW - Oscillation PY - 2009 U6 - https://doi.org/10.1016/j.wear.2008.06.004 SN - 0043-1648 VL - 266 IS - 1-2 SP - 167 EP - 174 PB - Elsevier CY - Amsterdam AN - OPUS4-18243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manier, Charles-Alix A1 - Theiler, Geraldine A1 - Spaltmann, Dirk A1 - Woydt, Mathias A1 - Ziegele, H. T1 - Benchmark of thin film coatings for lubricated slip-rolling contacts N2 - The light-weight approach and fuel economy targets in today's automotive engineering require tribosystems, which can withstand higher contact pressures associated with low coefficients of friction. The application of high-performance coatings represents one approach among others. This paper presents some recently developed DLC coatings (a-C:H and ta-C) as well as a novel coating-substrate system (Zr(C,N)) in a benchmark test procedure under slip-rolling conditions in the presence of liquid lubricants. Various coatings with different thickness, interlayer and substrates were evaluated for their slip-rolling resistance in different lubricants at ambient temperature and at 120 °C. Results indicate that some of these coating systems can withstand at least 10 million cycles under initial Hertzian contact pressures of up to Pmax = 3.500 MPa and oil temperatures of at least 120 °C associated with low coefficients of friction under mixed/boundary conditions. Surface of the coatings and the counter bodies were analysed and compared with untreated substrates. KW - Slip-rolling KW - DLC KW - Thin film coating KW - Zr(C,N) KW - Polyglycol PY - 2010 U6 - https://doi.org/10.1016/j.wear.2010.02.020 SN - 0043-1648 VL - 268 IS - 11-12 SP - 1442 EP - 1454 PB - Elsevier CY - Amsterdam AN - OPUS4-21196 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Scholz, C. A1 - Burbank, J. A1 - Spaltmann, Dirk T1 - Slip-rolling resistant steel alloys up to P0max of 3,920 MPa N2 - Downsizing (power-to-weight ratio) and higher speeds lead to a rise in Hertzian contact pressures in combination with an increase in surface or oil temperatures. Under such conditions, commonly used bearing steels, such as 100Cr6, reach their limits, creating a demand for alternative slip-rolling resistant steel alloys. The present work therefore compares the slip-rolling performance of various steel types with Maraging- and PM-type steel alloys such as e.g. CSS-42L™, ASP2012, BIMAX42+, in the Hertzian contact pressure range up to P0max of 4 GPa. Through-hardened 100Cr6H (AISI 52100), case-hardened 20MnCr5 (AISI 5120H) and nitrogen alloyed Croni-dur30 (AMS 5898) still compete in terms of slip-rolling and wear resistance and load carrying capacity, whereas Maraging- and PM-type steel alloys offer superior strength and toughness properties. KW - Steel KW - Alloy KW - Slip-rolling KW - Friction KW - Wear rate KW - Contact pressure KW - 100Cr6 KW - BIMAX42 KW - CSS-42L KW - ASP20212 PY - 2012 U6 - https://doi.org/10.1016/j.wear.2021.203707 VL - 474-475 SP - 203707 PB - Elsevier B.V. AN - OPUS4-52549 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -