Preparation and properties of Ni-P/Bi self-lubricating composite coating on copper alloys

Replacing Pb with low melting point Bi, Ni-P/Bi self-lubricating composite coating was successfully prepared using CuSn10 substrate by electroless plating. The microstructure and mechanical properties of Ni-P/Bi composite coating, Ni-P coating, CuSn10 substrate and Pb-containing CuSn10Pb10 material were investigated, and the sliding friction experiment with 45 steel was conducted on M200 ring-block tribometer. Results show that compared with the CuSn10 substrate and CuSn10Pb10 material, the hardness of Ni-P coating alloy and Ni-P/Bi composite coating alloy material is improved greatly. The coating alloy also enhances the impact toughness and crushing strength of CuSn10 substrate. Compared with the CuSn10Pb10 alloy, the friction coefficient and wear rate of Ni-P/Bi composite coated alloy are reduced by 40 % and 47 %, respectively. The wear surface of the Ni-P/ Bi composite coating material is smooth and flat, which can remarkably improve the adhesion and tear wear of the wear surface of CuSn10Pb10 material.