Effect of Y[sub.2]O[sub.3] Content on Microstructure and Corrosion Properties of Laser Cladding Ni-Based/WC Composite Coated on 316L Substrate

To improve the corrosion resistance of 316L substrate and lengthen its useful life in marine environments, Ni-based/WC/Y[sub.2] O[sub.3] cladding layers with different Y[sub.2] O[sub.3] contents were fabricated on 316L stainless steel using laser cladding technology. The influence of Y[sub.2] O[sub.3] additives on the microstructure and properties of the cladding coatings was investigated by using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, a microhardness tester, an electrochemical workstation and a tribometer. Results show that the metallurgical bonding is well formed between the coating and the 316L substrate. The coating consisted primarily of γ-Ni phase and carbides. Adding an appropriate amount of Y[sub.2] O[sub.3] can effectively refine the microstructure and inhibit the precipitation of the carbide hard phase; in addition, the added rare earth element can promote the solid-solution-strengthening effect of the cladding coatings, thus improving the microhardness and wear resistance of the cladding coatings and their electrochemical corrosion property in 3.5 wt% NaCl solution. The hardness of the Ni-based/WC coatings was substantially higher than that of the substrate, and it was greatest at a Y[sub.2] O[sub.3] content of 1%. The corrosion and wear resistance of Y[sub.2] O[sub.3] -modified Ni-based/WC composite coatings are significantly better than those of the composite coating without Y[sub.2] O[sub.3] .