Graphite and Nickel containing tin Bronze-steel bimetals as lead free bearing materials

Abstract

Ni was added into graphite-lead free tin bronze composite layers on surface of steel sheets by primary sintering mixed powders of graphite and CuSn10 with addition of a nickel nitrate and poly(vinyl alcohol) (PVA) solution in an ammonia decomposition atmosphere. The reduced Ni particles attached on the surface of graphite and CuSn10 particles help to link them together. The conjunction of graphite and CuSn10 matrix in the composites treated by cold rolling and second sintering is well, and no cracks can be observed at the interface between graphite and CuSn10 matrix. The addition of Ni will improve the interface; increase hardness, anti-friction and anti-wear performance of the composites greatly. The Ni containing graphite-CuSn10 composites demonstrate better tribological performance than CuSn10Pb10 alloy, which makes them promising lead free bearing materials for heavy load engines.