Abstract: Ni60/WC composite coatings were successfully prepared on Cr12MoV substrate by laser cladding technology. The effect of laser power on the mechanical properties of the composite coatings was studied. The microstructure, microhardness and wear resistance of the composite coatings were characterized by SEM, Vickers hardness tester, reciprocating friction and wear tester, respectively. The wear mechanism of the composite coatings was further revealed. The results show that lower laser energy input cannot satisfy the melting requirements of WC particles, which weakens the forming quality of composite coatings. The WC particles in composite powders can be fully melted to generate Ni₂W₄C, M₇C₃, M₆C type carbides under relatively higher laser power conditions. With the increase of laser power, the wear resistance of the Ni60/WC composite coatings first increases and then decreases, where the WC particles produce fine grain strengthening and induce the in-situ carbide hard phase to improve the mechanical properties of the composites. In a certain range, with the increase of laser power, the average microhardness of the composite coating increases, reaching 852.35 HV0.2 at most, and the average friction coefficient and wear rate decrease, reaching 0.117 45 and 0.5849×10^-8 mm²/N at least, respectively. The furrow and flake peeling on the wear scar surface are reduced, and the wear resistance of the coating is significantly improved. However, with the increase of laser power, the mechanical properties of the composite coating are reduced due to the large internal residual thermal stress and grain coarsening.

Key words: in-situ carbide formation, Ni60/WC coating, laser cladding, wear resistance