A Research on the Hardness of Pulse Electrodeposited Ni-W-P-SiC Composite Coatings

The hardness of pulse electrodeposited Ni-W-P-SiC composite coatings is studied. The results show that both variation in duty ratio and pulse frequency have great influence on the hardness of the deposite. The hardness of the coating deposited by pulse current is 100~200Hv higher than that of by direct current in different conditions. The hardness of the coating will increase with the rising of heating temperature reaching the peak at 600℃ and will decrease sharply as the temperature rises further. The hardness of the coating also increase as heat-treatment time extending and the optimum value is obtained after 3 hours of heating at 400℃. With the rising of heating temperature and the extending of heat-treatment time, more and more SiC particles diffuse from coating to substrate.