Microstructure and wear properties of crystalline W alloy coatings prepared by electrodeposition

Electroplating Ni-W coatings have been prepared on medium carbon steel substrate using nickel sulphate and sodium tungstate as precursors. The elemental composition, microstructures, phase composition and performance of the coatings were analyzed by SEM, EDS, AFM, XRD, microhardness tester and wear tester. The surface morphologies after wear were observed and the wear mechanism was analyzed. The results show that Ni-W alloy coatings are not found to have obvious flaws and and have a good bond with the matrix. The crystalline Ni-W coating is composed of Ni-based solid solution and the coatings before and after heat treatment are crystalline structure. The microhardness of the coatings increases with increasing heat treatment temperature, reaching its maximum value(1 100 HV0.3) for heat treatment at 500 ℃, and then decreases for heat treatment at higher temperatures. Due to the low surface roughness of the coating with heat treatment, high microhardness, the crystalline Ni-W coating has strong wear resistance.