Microstructure and wear resistance of laser cladding Co+Ni/WC alloy composite coating

Laser cladding Co-based composite coating(Co+Ni/WC) have been obtained on low carbon steel substrate. Microstructure and wear resistance of the composite coatings were investigated compared with the Co-based coating(Co60). It is indicated that the Co60 coating was composed of primary dendrite of γ-Co and the eutectics of γ-Co+Cr₂₃C₆ among the interdendritics, and Co+Ni/WC composite coatings were composed of γ-Co dendrite and the small eutectics, which consists of γ-Co, Cr₇C₃, Co₃W₃C and unmelted WC particles. With more WC particles, there was further influence to Co60 coating that the directional solidification of dendrite was changed and the dendrite was finer. Owing to the Ni alloy wrapper, the WC particles had been protected from melt for the diffusion reaction on interface between the WC particles and the Co based alloy. Compared with Co60 coating, the hardness and wear resistance of the Co+Ni/WC composite coatings had been improved and the wear resistance of the Co+20% WC composite coating was twice of that of the Co60 coating.