La2O3 Effect on Microstructure, Mechanical and Tribological Properties of Ni-W Coatings

In this work, a Ni-W-La2O3 composite coating was prepared by electrodeposition method. Microhardness tester and environmental scanning electron microscope equipped energy dispersive spectroscopy were employed to investigate the microhardness and the surface morphology of the composite coatings respectively, and the high temperature friction behavior and corrosion resistance of the coatings against molten glass were investigated by using a high temperature tribometer. The results show that La2O3 can refine the microstructure effectively, and make the element distribution uniform, which leads to the increase of average microhardness. La2O3 particulates decrease the friction coefficient from nearly 0.48 to about 0.22 during the composite coatings sliding against the molten glass at about 973 K, and also decrease the variation of the friction coefficient value remarkably. Furthermore, La2O3 particulates can improve the corrosion resistance of the Ni-W alloy at high temperature effectively, and the mechanism of anti-friction and anti-corrosion is also discussed.