Tribological performances of graphite–MoS2 coating at various high temperatures

Abstract

The tribological performances of the graphite–MoS2 coating deposited on the disc specimen, whose material is GCr15 steel, are experimentally investigated under high temperatures. Effects of graphite content, applied load, rotational speed and test temperature on the coefficient of friction and wear scar width of the coating are evaluated. The graphite–MoS2 coating with 20 wt% graphite addition exhibits the relatively small coefficient of friction and wear scar width at 200 ℃. At or beyond 400 ℃, the coating's lubricating effect is severely deteriorated with the testing time. At 200 ℃, there exists a critical applied load of 10 N and a critical rotational speed of 1250 rpm beyond which the MoS2 coating with 20 wt% graphite content is worn through and brings out a large coefficient of friction. The test results indicate that adding 20 wt% to 33 wt% graphite to MoS2 coating leads to an obvious reduction of the coefficient of friction and wear scar width for the coating at 200 ℃.