Effect of Growth of Intermetallic Compound Layer in Tin Overlay to Bearing Performance

The sliding bearings for diesel engines include Pb, which is one of environmentally hazardous substances and the usage will be limited in near future. Therefore, the Pb free bearing which consists of pure Sn overlay and Cu-5 mass%Sn-1 mass%Ag sintered lining was developed. After engine bench test of the bearing, Cu-Sn intermetalic compounds are formed at the interface between Sn overlay and Cu alloy lining. Total thickness of the Cu-Sn intermetalic compounds is proportion to square root of time and is not affected by oil and pressure. In the results of a seizure test under local contact condition, the heat treated bearings which had intermetalic compounds layer, had approximately the similar seizure resistance to the bearings without intermetalic compounds. There is no problem by formation of the Cu-Sn intermetalic compounds.