Effect of Heat Treatment on Microstructure and Tribocorrosion Performance of Laser Cladding Ni-65 WC Coating

Abstract

The Ni-65wt%WC cladding layers were prepared on the surface of Q235 using laser cladding technology, in which the effect of heat treatment on microstructure and tribocorrosion performance was investigated. The results showed that the coating is mainly consisted of Ni, WC, and W2C, and a significant diffusion phenomenon is formed between the interfaces of WC/Ni matrix, benefited for the improvement of bonding layer between WC/Ni-based matrixes. Meanwhile, the crystallization of WC particles after heat treatment was more obvious than untreatment; the Ni matrix grain size was also grown remarkable, leading to the lower hardness and weaker plastic deformation resistance of Ni-65wt%WC coating. And the erosion results showed that the wear rate of coating gradually decreased with heat treatment temperature increasing, while brittle WC was not suitable for high impact wear conditions. Furthermore, with the increase of heat treatment temperature, the reciprocating wear performance showed that the friction coefficient and wear rate of Ni-65wt%WC coating decreased. And the friction coefficient and wear rate of the coating (700°C) in 3.5% NaCl solution were 0.15 and 4.82×10-8 mm3·N-1·m-1, respectively. Therefore, the comprehensive comparison showed that Ni-65WC coating had better performance in low impact reciprocating testing under corrosion environment, and heat treatment was helpful to further improve the tribocorrosion performance of laser cladding Ni-65wt%WC coating.