Influence of heat-treatment on structure and properties of electroless Ni-P-SiC coating on ZL102 alloy

Ni-P-SiC composite coating on the surface of ZL102 alloy was prepared by direct electroless. After heat treatment at different temperature, the structure and the morphology of the coating were analyzed by XRD, DSC and SEM, and the bonding strength, hardness, corrosion resistance and wear resistance of the coatings were tested too. The results show that the coating consists of an amorphous phase coexisting with a crystalline phase. The amorphous phase is crystallized into crystalline phase during heat treatment. The microhardness of the deposit increases with the increase of heat treatment temperature below 400, after it decreases, and the microhardness can reach 1395.28 HV at 400. After heat treatment at 400 for 1 h, the inter-diffusion between the deposits and substrates is mainly the diffusion of Ni and P into aluminum alloy. The composite coating has high bonding strength and the corrosion resistance and wear resistance of the substrate are considerably improved. However, the coating has more corrosion resistance than that of the heat treatment coating. ©, 2014, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.