Effect of Laser Power on Microstructure and Wear Resistance of WCP/Ni Cermet Coating

Laser cladding nickel-based alloy coating (Ni60) and nickel-based composite coating doped with WC particles by 35% (WCP/Ni) were produced on the low-carbon steel substrate by CO2 continuous wave laser with power of 5 kW using the injected powder technique. The effect of laser power on microstructure and wear resistance of laser cladding WCP/Ni cermet coating was investigated. The WCP/Ni alloy coating with evenly distributed WC ceramic phases and the better bond with the substrate alloy was obtained at a power of 2.2 kW. Diffusion solution reaction happened between WC particles and the substrate alloy during laser cladding, and led to the formation of block rich-tungsten carbide on the edges of the WC particles, especially at higher power. The WCP/Ni alloy coating consists of the undissolved WC particles, the block or dendritic rich-tungsten carbide, the bar-like rich-chromium carbide, and dendrite solid solution and eutectic structure among the carbides. Microhardness and wear resistance of the WCP/Ni coating at different powers were much higher or better than those of Ni60 alloy coating, and the best results were obtained at power of 2.2 kW.