High WC content promotes continuous eutectic structure formation and enhances wear resistance in WC/CeO₂-Fe laser cladding coatings

WC/CeO₂-Fe composite coatings with varying WC contents (0, 15, 20, and 25 wt%) were prepared on 27SiMn steel substrates via laser cladding. The effects and underlying mechanisms of WC addition on the microstructure and tribological behavior of the coatings were systematically investigated. Experimental results revealed that increasing WC content significantly enhanced the coating density and promoted the in-situ formation of hard carbide phases, including W₂C, M₂₃C₆, and M₇C₃. The dendritic grains were markedly refined, and the eutectic morphology evolved from isolated rods into continuous bright-white structure. At 25 wt% WC, the coating achieved the highest average microhardness (~635.1 HV_0.2), approximately 42 % higher than the WC-free coating, and the lowest wear rate (3.52 × 10⁻⁶ mm³·N⁻¹·m⁻¹), one order of magnitude lower than the WC-free coating. The thermal decomposition of WC released abundant W and C atoms, which reacted with Fe and Cr in the matrix to form uniformly distributed carbides, contributing to a rigid skeleton and refined grain structure. This study elucidates how high WC content promotes continuous eutectic structure formation and improves the wear performance of WC/CeO₂-Fe coatings, providing a promising approach for the surface reinforcement of 27SiMn steel in heavy-duty mining applications.