Effects of Y2O3 on Microstructure and Corrosion Properties of Laser Cladding Composite Coatings on 304 Stainless Steel Substrate

Ni625/WC composite coatings added with different amounts of Y2O3 were prepared on the surface of 304 stainless steels by laser cladding. This study focused on the microstructure characteristics, microhardness, and corrosion performances of Ni625/WC composite coatings. The results showed that Y2O3 can effectively improve the corrosion resistance of the composite coatings. The microstructure from the bottom to the surface of composite coatings consists of plane crystal, cellular crystal, columnar crystal and equiaxed crystal. The Y2O3 content of optimum composite coating was 1.0%. Its microhardness was three times that of matrix material. In addition, the corrosion current density of the composite coating was only 2% of Ni625/WC coating, which was attributed to the good properties of Y2O3 and appropriate Y2O3 refined microstructure.