Microstructure and Wear Property of Graphene Nanoplatelets Reinforced Nickel-Based Composite Coating by Laser Cladding

Nickel-based composite coatings containing graphene nanoplatelets (GNPs) were prepared on Q235 steel using laser cladding. In order to retain the multilayer GNPs in the composite coatings after laser cladding, NiGNPs were prepared by electroless nickel plating on GNPs as the additive phase. All the coatings contain γ-(Ni, Fe), Cr23C6, Cr7C3, Fe3C and WC phases, and multilayer GNPs were retained successfully in the composite coatings. With the addition of GNPs, the microstructure of the coatings was obviously refined and the content of Cr-C compounds were increased along with its changed morphology. The mean microhardness of the Ni-based composite coatings containing GNPs was significantly improved compared to that of Ni45 coating, and the maximum microhardness was 745.06 when 20% NiGNPs was added. The results indicated that, due to the refinement and lubricating effects of GNPs, the friction coefficients of composite coatings were reduced and the wear resistance was improved compared to Ni45 coating.