Microstructure and dry sliding wear behavior of laser clad Ni-based alloy coating with the addition of SiC

A mixture of 30 vol.% SiC and 70 vol.% Ni-based alloy was clad onto steel substrate using laser multi-track overlapping process. Microstructure and dry sliding wear behavior of the overlapped cladding were studied. SiC particles completely dissociated during the processing. The microstructure of the cladding layer differs widely throughout the cladding layer, typical microstructure is composed of net-like dendrite M23(C,B)6, cellular-dendrite Ni31Si12, γ-Ni+Ni3B interdendritic lamellar eutectic, with very small amount of spherical graphite in the upper part of the cladding layer. Interestingly, significant amounts of net-like M23(C,B)6 carboboride dendrites as wear resistant skeleton were formed and uniformly dispersed in the cladding layer. Meanwhile, small graphite spheres scattered in the upper part of the cladding layer can also give contribution towards reducing friction as a self-lubricant. The novel microstructure, therefore, is beneficial for wear resistance. Friction and wear tests without lubricant show that the friction coefficients of the cladding layer is less than that of hardened steel, but the sliding distance characteristics of the friction coefficients of the cladding layer are in good agreement with that of the steel. There exists an approximately linear relationship between wear weights and sliding distances, and wear weight increases with an increase of sliding speed at the same sliding distance. Wear rate slightly increases with an increase of sliding distance, and the wear rate of the cladding layer is about one order less than that of the hardened steel.