Enhanced wear resistance of laser cladded WC-Ni composite coatings by picosecond laser surface texturing

Abstract

In this work, a picosecond laser was applied to prepare pit textures on laser cladded WC-Ni composite coatings with 20 wt% WC content. The mechanism of laser interaction with the composite phase of the coating was investigated, and the effect of surface texture on tribological behavior and wear resistance was further analyzed. The constituent phases of the textured coating remain essentially the same as the original coating. The presence of WC particles in the WC-Ni composite coating makes the removal mechanism of the composite coating by the picosecond laser consist of thermal ablation of the Ni-based metallic binder phase and phase explosion of the WC particle phase. The hardness of the binder phase region near the texture is enhanced (>500 HV_0.2) due to laser thermal effect. The friction coefficient (about 29.24 %) and wear rate (about 53.56 %) were significantly reduced compared to the original coating. It can be attributed to the circular pit texture that traps the abrasive debris and stores the lubricant, indicating that the surface texture plays a positive role in tribological performance.