Abstract: The effect of different Mo additions on the microstructure and wear resistance of the nickel-based alloy coating produced by plasma cladding was investigated using optical microscope, scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), and sliding wear test. The results show that the γ(Ni, Fe) solid solution with a face-centered cubic crystal structure is presented accompanied by the M₇(C, B)₃ with a hexagonal crystal structure and Cr₂B with a tetragonal crystal structure in the nickel-based alloy coating. The obvious component segregation exists in the nickel-based solid solution. The addition of Mo does not change the phase composition, though the relative content of boride and carbide increases. Meanwhile, the component segregation decreases gradually then disappears finally with the increasing Mo content. The equiaxed crystals come into being in the Mo-modified coating. The addition of Mo increases the wear resistance. The wear resistance increases with the increasing Mo content when its content is lower than or equals to 6%. On the contrary, the wear resistance decreases again when the Mo content equals to 8%. The addition of Mo can homogenize the component, promote the formation of equiaxed crystals, and increase the relative quantity of boride and carbide. All these results are beneficial to increasing the wear resistance of the cladding coating.

Key words: plasma cladding; nickel-based alloy; Mo; microstructure; wear resistance