Effect of WC particles preparation method on microstructure and properties of laser cladded Ni60-WC coatings

Ni60 and WC composite coatings were prepared on 17-4PH martensitic stainless steel with 30 wt% agglomeration-sintering WC (AS-WC) or 30 wt% sintering-crushing WC (SC-WC) respectively. The results show that in the AS-WC doped coating, the WC particles are more easily melted and dispersed, and a large amount of acicular (Fe, Ni, W)23C6 carbides are dispersed throughout the coating. However, in the SC-WC doped coating, the melting is quite limited and only occurs at the outer edge of the WC particles, and a small amount of (Fe, Ni, W)23C6 precipitated in the coating. Owing to this microstructure difference, the AS-WC doped coating possesses higher hardness, the microhardness reached 622.27 HV0.2 which is 25.5% higher than the normal Ni60 coating without WC, and 10.0% higher than the SC-WC doped coating. Moreover, the wear resistance test results indicate that the AS-WC doped coating has the best wear resistance compared to the SC-WC doped coating and normal Ni60 coating without WC. Those findings help us to obtain better Ni-based high hardness coatings for industrial applications.