Tribological property of plain bearing with low frictional layer

This paper describes the excellent frictional properties of a newly developed lead-free aluminum alloy bearing with a low frictional layer on its inner surface, which consists of a molybdenum disulfide (MoS2) layer deposited directly without any binders such as resin. The thickness of the layer is in sub-micron levels. This bearing has high potential in reducing the friction losses within an automotive engine in pursuit of better fuel economy. Scratch tests under dry conditions clearly showed that the newly developed bearing exhibited less adhesion at higher load compared to current materials. In addition, the microscopic observation of the scratched surfaces demonstrated that the MoS2 layer and its transferred film existed on both the bearing surface and the depressor surface, respectively. Measurements of the coefficient of friction on stop–start bearing tests confirmed that the newly developed material lowered friction and also shortened time to running-in under start–stop operation experienced in recent automotive engines. Observation of the sliding surfaces clarified that the surface layer of MoS2 gave lower adhesion, resulting in lower coefficient of friction.