Effect of Ta Content on the Microstructure and Properties of Laser Cladding Ni60A/WC Composite Coatings

Our aim is to solve the problems of cracking and porosity of laser cladding Ni60A/WC high-hardness composite coatings. Ta powder was added to synthesize TaC in situ with C in a molten pool, to reduce the carbon content of the metal matrix and inhibit the generation of carbon oxide gases to obtain a new Ni60A/WC composite coating with no defects, reasonable hard phase distribution, and excellent properties. The phase composition, microstructure, elemental distribution, and mechanical properties of the composite coating were studied by x-ray diffraction, scanning electron microscopy, and tribometry. The results show that Ta more easily combines with C. Adding an appropriate amount of Ta powder inhibits the formation of other carbides and carbon oxide gases, and significantly reduces the cracking sensitivity of the cladding layer. The fine TaC particles synthesized in situ are used as nucleation sites to significantly refine grains and improve microstructure uniformity. In addition, TaC particles with high hardness and good wear resistance also improve the microhardness and wear resistance of the cladding layer, which can provide a reference for the preparation of nickel-based composite coatings with excellent properties.