Effect of Graphene on Microstructure and Properties of Laser Cladding Ti-C-Nb-Reinforced Ni-Based Coating

Laser cladding experiments were performed on Ti-C-Nb and Ti-C-Nb-graphene powders. The microstructure, microhardness, and strengthening mechanism of the coatings were analyzed using X-ray diffraction (XRD) and backscattered electron (BSE) imaging. The microstructural and phase analyses of the coating show that the coating is metallurgically bonded to the substrate. Moreover, the microstructure of the coating is composed of gamma-Ni, Cr23C epsilon, TiC, and (Ti, Nb) C granular phases. TiC and (Ti, Nb) C particles are dispersed in the gamma-Ni grain boundaries and in the grains. The addition of graphene can remarkably refine the grain size and facilitate an evenly distributed particle phase. Furthermore , the microhardness of the coating can be improved remarkably.