Unraveling the lubrication mechanisms of lithium complex (LiX)- and polypropylene (PP)- thickened greases in fretting – Part I: Fretting experiments and surface analysis

Greases with two different thickeners, namely lithium complex (LiX) and polypropylene (PP), three base oil viscosities were investigated in fretting varying displacement amplitude applied normal load. The material combinations silver-coated copper/silver-coated copper (Ag/Cu vs Ag/Cu) steel/steel investigated. Fretting maps of four the six evaluated greases constructed as a tool to better understand compare lubrication mechanisms grease types. Parameters such load, amplitude, combination, contact area growth, thickener type, viscosity, chemical effects, etc., all influence lubricating properties prevailing regime. This study shows importance understanding application its conditions, well how types are affected by test parameters. Very effects found for same depending on conditions. Surface analysis formed wear marks is presented. • Grease-lubricated greases. Two systems used. Test parameters type strongly properties. marks. constructed.