Tribological properties of laser cladded Gr-CBN-Ni coating

Graphene（Gr）-CBN-Ni composite coating layer was fabricated by laser cladding through pre-set the mixture of nickel, graphene and CBN powders on AISI 4140 steel substrate. Microstructures and surface and sectional surface morphologies were studied using scanning electron microscopy (SEM), XRD and Raman spectroscopy. It is proved by X-ray diffraction (XRD) patterns and Raman spectra that graphene and CBN exist in the laser cladded coating layer. The nanomechanical properties and wear and friction properties were studied. The test results show that as the CBN content increases, the coating layer has better properties. The hardness and modulus of coating layer were significantly enhanced with the CBN content increasing. The average hardness were 4.3 GPa and 6.2 GPa, the average modulus were 101 GPa and 140 GPa, respectively. For 6% CBN content coating, the friction coefficient reduced to 0.15, while the substrates was 0.2, and the wear loss was only the half amount compared with that of substrates.