Effect of Ti addition on microstructure and tribological properties of laser cladding Ni35/WC coating in an oxygen-free environment

In this study, Ni35/WC coatings with different Ti contents were prepared by laser melting coating in two environments (oxygen-free and ordinary atmospheric environments). Effects of Ti addition on microstructure characteristics and dilution rate of the composite coating in an oxygen-free environment were investigated. Corresponding tribological properties and microhardness of the coating were evaluated. It is shown that the laser cladding in the oxygen-free environment reduced the splash phenomenon during the preparation of the Ticontaining coating, thereby reducing the number of defects in the coating. After adding Ti, the dilution rate of the coating increased significantly. The oxygen-free environment during coating preparation could effectively decrease the dilution rate, which made the microhardness distribution of the coating smoother with significantly improved friction stability. By analyzing the worn surface of the coating, it was found that the addition of Ti could effectively decrease adhesive wear and oxidation wear of the Ni35/WC coating. An oxygen-free environment can keep more actual Ti content in the coating, leading to lowered wear rate.