Effect of Y2O3 Content on Microstructure and Corrosion Properties of Laser Cladding Ni-Based/WC Composite Coated on 316L Substrate

Abstract

To improve the corrosion resistance of 316L substrate and lengthen its useful life in marine environments, Ni-based/WC/Y2O3 cladding layers with different Y2O3 contents were fabricated on 316L stainless steel using laser cladding technology. The influence of Y2O3 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 Y2O3 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 Y2O3 content of 1%. The corrosion and wear resistance of Y2O3-modified Ni-based/WC composite coatings are significantly better than those of the composite coating without Y2O3.