Influence of WC particle behavior on the wear resistance properties of Ni–WC composite coatings

Nickel-based and tungsten carbide (WC) composite coatings were prepared by laser cladding under different laser beam powers. The microscopic morphology and distribution of WC particles in a laser-clad Ni–WC coatings were characterized by scanning electron microscopy (SEM). Two effective methods to avoid the stress concentration and cracks were used. One is the gradient coating with WC hard phase varied gradually from the substrate to the top of the coating using three-step laser cladding. The other is the coating where WC particles, with a marked gradient distribution at interface between the matrix and WC, were uniformly incorporated in the coating by optimizing WC particle concentration, laser power and thickness of the layer. The wear test results show that three-step laser-clad gradient layer is not recommended especially for long-term wear applications because of the complicated laser processing and poorer interface between the matrix and WC particles.