Microstructure and mechanical properties of laser deposited Ni/WC metal matrix composite coatings

Abstract

In the present study, the feasibility of laser metal deposition of WC reinforced Nickel composite coatings was investigated for the application of hardfacing coating on copper. Ni/60WC MMC were fabricated on the surface of copper with a buffer layer of hastelloy C-276. Additional sets of samples were deposited on a 1020 mild steel substrate. Three principal experiments were conducted in a systematic order to understand the microstructural evolution of Ni/60WC MMC. A multi-track, single-track deposit, and remelting of the as-deposited surface were systematically investigated by optical and scanning electron microscopy. The results revealed microstructural element such as dendrites, equiaxed structure, eutectic structure, and several other complex carbide structures. It was observed that the presence of three principle phases in the deposit consisted of the primary WC, dendritic Ni, and a eutectic structure. Microhardness of the laser deposited samples indicated the gradual variation in hardness as the deposition transits from a highly conductive soft material to a hard facing coating. Homogenization of WC in Ni matrix was well realized in this study.