Improvement in mixed lubrication characteristics of electromagnetic clutch coated with DLC-Si film by controlling surface roughness and providing micro-groove

This study investigated how surface roughness of steel disk coated with a Si-containing diamond-like carbon (DLC-Si) film has an effect on friction characteristics, i.e., sliding velocity dependence of friction coefficient, under oil lubricated condition via friction experiments and numerical analyses using mixed lubrication models. It was clarified to be effective for DLC-Si film to have surface roughness of Jz_JIS = 3 to 4 (im in order to suppress frictional vibration caused by stick-slip. In addition to the roughness of surface coated with DLC-Si film as a design guideline of sliding surface of electromagnetic clutch with excellent μ-v characteristics, it was found effective for the mating plate to have micro groove structure with depth of 10 μm and pitch of about 100 μm. It was suggested that the surface roughness and the micro groove maintain solid contact even if oil film formation enhances as sliding velocity increases, which results in boundary lubrication.