Microstructure and dry sliding wear behavior of hot-extruded AlSiCuPb bearing alloys

The microstructures, mechanical properties and dry wear behavior of hot-extruded AlSiCuPb bearing alloys have been studied. It showed that the hot-extruded AlSiCuPb alloys possessed microstructures with uniformly distributed lead particles and fine broken grains of silicon, and exhibited further improved mechanical properties in comparison to the stir cast ones. With increasing the lead content, the wear rate decreased greatly and wear rate-load curves took different form for extruded bearing alloys containing 20% and 25% lead. Optical observation revealed the reason was formation of a black compact film of lubricant covering almost the entire worn surface of specimens at highly applied load level. This film is a mixture of different constituents containing the elements Al, Si, O, Fe and Pb.