Wear behavior of electron beam remelting modified Ni/WC thermal spray coatings

Abstract

Ni/WC composite coatings were prepared by combining thermal spraying and electron beam remelting. Characterization methods such as SEM, EBSD and XRD were used. The effect of electron beam remelting beam current on the corrosion and wear resistance of Ni/WC composite coatings was investigated. The microstructure showed that hard carbides and borides such as W₂C, Cr₂₃C₆, and M₃B were generated within the remelted coating. Compared to the thermal spray specimens, the hardness of the 16 mA specimen was increased by a factor of 1.47, and the hardness of the 22 mA specimen was also increased by a factor of 1.14. The results of the corrosion experiments showed that the 16 mA specimen had the lowest corrosion current density and the highest corrosion potential, which showed the best corrosion resistance. Wear experiments were carried out by using SiC balls as the counterbodies. The results showed that the wear resistance of both 16 mA and 22 mA specimens under dry friction with 3.5 % NaCl solution conditions was improved compared to the thermal spray coating. The 22 mA specimens showed more obvious subsurface damage. The wear mechanism of thermal spray coatings is mainly abrasive, and the wear mechanism of remelted coatings is mainly abrasive and adhesive.