Tribological Behavior of TiC/a-C:H-Coated and Uncoated Steels Sliding Against Phenol–Formaldehyde Composite Reinforced with PTFE and Glass Fibers

Abstract

Tribological experiments on phenol–formaldehyde composite reinforced with polytetrafluoroethylene (PTFE) and glass fibers were performed against 100Cr6 steel and TiC/a-C:H thin film-coated 100Cr6 steel. In both cases, the coefficient of friction increases with increasing sliding distance until a steady-state value is reached. Although the steady-state values of the coefficient of friction are very close and ultralow, the wear rate of the PTFE composite liner at a long sliding distance (1,000 m) is reduced when the steel ball is coated with the TiC/a-C:H coating. This behavior is mainly attributed to the smoother surface after long sliding and the improved wear resistance of TiC/a-C:H coating. PTFE transfer films are evident on the surfaces of the hard counterparts. The average thickness of the transfer film on TiC/a-C:H-coated surfaces is about 3.8 nm. On the surface of uncoated steel ball, a continuous but non-uniform transfer film of around 13.9 nm average thickness was found.