Effect of CeO₂ Adding Content on Microstructure and Properties of Laser Cladding WC Reinforced Nickel-Based Alloy Coating

The mixed powders with nickel-coated tungsten carbide powder and CeO₂ powder was used as raw materials, WC reinforced nickel-based alloy coating was prepared on the surface of 42CrMo steel by laser cladding technique. The effect of mass fraction (0-2.0%) of CeO₂ in raw materials on the phase composition, microstructure, hardness and wear resistance of the coating was investigated. The results show that the phase of the coating with CeO₂ was composed of γ-(Ni, Fe) solid solution, Ni₃Fe, WC, Cr₂₃C₆, M₇C₃ (M=Fe, Cr) and a small amount of CeNi₃. A good metallurgical bond was formed between the coating and the substrate. When the mass fraction of CeO₂ was 1.0%, the structure was dense and uniform, and the refinement effect was the most obvious. With increasing CeO₂ content, the hardness of the coating increased first and then decreased, and the friction coefficient and the amount of wear decreased first and then increased. The average hardness of the coating with 1.0% CeO₂ was the highest, which was 956.0 HV, and increased by 29% compared with that without CeO₂; the average friction coefficient and the average wear volume were the smallest, which were 0.383 and 11.25×10^-3 mm³, and were reduced by 27% and 20% compared with those without CeO₂, respectively. The wear resistance of the coating with 1.0% CeO₂ was the best, and the wear mechanism of the coating was slight abrasive wear.