LAUSR

Abstract To investigate the uniqueness of graphene, compared with graphite, in the preparation of TiC reinforced composite coating, the composite coatings were obtained from Ni-Cr-Ti-graphene/graphite powder by laser cladding. The phase composition and microstructure of composite coatings are detected by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive spectrometry (EDS), respectively. The phase composition of the composite coatings both mainly consist of Ni-Cr-Fe, Ni3Ti, Cr2Ti and TiC. The research results indicate that the crystal structures of in-situ synthesized TiC in the composite coatings have great difference, in detail, TiC crystals in the graphene-coating and the graphite-coating are dominated by equiaxed and dendrite crystals, severally, which is due to the reaction of two-dimensional graphene with Ti has better diffusion kinetics than that of three-dimensional graphite under rapid solidification of molten pool. The maximum microhardness of graphene-coating is 1000.3 HV0.1, which is about 4 times as hard as the substrate. The composite coatings show significant improvement in hardness and wear resistance than the substrate. The graphene-coating possesses more uniform hardness distribution and better wear resistance than that of graphite-coating, which is benefited from the uniform distribution of TiC equiaxed crystals in the graphene-coating.