TY - JOUR A1 - Burbank, John A1 - Woydt, Mathias T1 - Friction and wear reductions in slip-rolling steel contacts through pre-conditioned chemical tribofilms from bismuth compounds JF - Wear N2 - Downsizing in mechanical systems requires effective lubrication strategies to ensure that increased contact stresses do not cause critical material failure during operation. Additionally, eco-toxicological consideration are becoming increasingly important. In this regard, the goal of this investigation is to transfer the running-in phase into the final step of the mechanical finishing process through the targeted pre-conditioning of novel, high toughness steel bearings without thermo-chemical treatments and compare these to conventional, case-hardened Steels. Pre-conditioning involved implementation of the ecologically sustainable, bismuth-based additives to generate chemically reactive tribofilms on slip-rolling contacts by using a formulation with a high concentration of tribofilm forming additive. Generated tribofilms were analyzed by Raman spectroscopy to elucidate their molecular composition and, ultimately, determine the reaction mechanisms of bismuth-based tribofilm formation. Tribofilm-protected samples were subjected to slip-rolling endurance testing in a factory fill engine oil without pre-conditioning additives to determine the influence of pre-condition tribofilms on friction behavior and wear performance. It was observed that pre-conditioned tribofilms from the bismuth-based additives were able to yield lower coefficients of friction (COF) and profilometric wear coefficients than for Steels without pre-conditioning. Moreover, COF values under mixed/boundary conditions approaching and even less than 0.04 were achieved, thereby rivaling DLC-coated alloy equivalents. KW - tribofilm KW - bismuth KW - carbamate KW - slip-rolling KW - friction KW - wear PY - 2016 DO - https://doi.org/doi:10.1016/j.wear.2016.04.004 SN - 0043-1648 VL - 360-361 SP - 29 EP - 37 PB - Elsevier B.V. AN - OPUS4-35919 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Woydt, Mathias A1 - Burbank, J.-Th. A1 - Spaltmann, Dirk T1 - Generation of defined tribofilms and their stability under slip-rolling in a 2disk test rig JF - Materials performance and characterization N2 - In the present work it was shown that the performance of tribofilms which were generated in 2Disk test rigs on widely used reference steels during slip-rolling in the mixed/boundary lubrication regime at 120°C is compared to those created on alternative steels. KW - slip-rolling KW - 2Disk KW - friction KW - wear KW - tribofilms KW - additive KW - test method PY - 2018 DO - https://doi.org/10.1520/MPC20170078 SN - 2379-1365 SN - 2165-3992 VL - 7 IS - 3 SP - 213 EP - 225 PB - ASTM International CY - West Conshohocken, Pa. AN - OPUS4-46304 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -