Wear mechanisms and micro-evaluation of WC + TiC particle-reinforced Ni-based composite coatings fabricated by laser cladding

Abstract

To enhance the quality and wear-resistance of metal-based composite coatings, Ni62 composite coatings were prepared by laser cladding 65Mn surfaces with WC and TiC as reinforcing phase particles. The effects of the laser power and content of the reinforcing phase on the microstructure, element distribution, phase composition, microhardness, friction, and wear properties of the composite coatings were investigated. Focus was placed on the cracking and wear mechanisms of the coating. The metallurgical binding zone exhibited a serrated morphology. The growth patterns of the crystals of the cladding layer resulted in the formation of columnar, cytosolic, and dendrite (or equiaxed) crystals. The main physical phases of the composite coating were the solid-solution (Ni, Cr, Fe), CW3, and Ti composite phases. There were two primary cracks in the cladding layer, one penetrating from the coating to the substrate, and the other occurring mainly at the interface between the cladding layer and the substrate. CeO2 incorporation led to refinement of the cladding layer and a significant reduction in the surface and cross-sectional defects. Wear of the coating was mainly caused by the alternating effects of adhesive, delamination, and abrasive wear.