Abstract: Ni-SiC composites coating on the Al alloy with smooth surface, good interior quality and tight combination with substrate is obtained by the pretreatment such as chemical zinc coating and nickel pre-electroplating. The effects of the SiC particle composition of the electrolyte , the current density,the stirring rate, the pH of the electrolyte, the temperature on the volume fraction of SiC deposited in the Ni layer, thickness and hardness of the coating are studied. The results show that these technical variables have remarkable effects on the codepositing rate of Ni-SiC coating, hardness and the volume fraction of SiC particles. When the SiC particles composition of the electrolyte is 120 g/L, SiC in the coating is 8.5% in volume fraction, and the hardness is 504.6 HV, which is 6 times of pure Al(82.5 HV), 2 times of pure Ni(242.5 HV).

Key words: Aluminum alloy Nickel, Composites coating SiC particles