Effect of SiC content on the microstructure and wear resistance of Ni45 coatings by laser cladding
摘要
Ni45–SiC composite coatings with 0, 10, 20, 30, and 40 wt.% SiC were prepared on 316L stainless steel by laser cladding to enhance load-bearing capacity and wear resistance under dry sliding conditions. Phase composition, microstructure, hardness and tribological performance were systematically characterized by XRD, SEM/EDS, microhardness tests and wear experiments. The coatings mainly consisted of a γ-Ni solid-solution matrix. XRD and SEM/EDS results suggest that the addition of SiC promoted the formation of Ni–Si silicides and Cr-rich carbide phases, which may be associated with the partial decomposition or dissolution of SiC in the molten pool. Meanwhile, the microstructure evolved from coarse dendrites to refined cellular and columnar-cellular crystals. Accordingly, the microhardness increased from 450.43 to 897.18 HV₀.₂, and the wear rate decreased to 1.98 × 10⁻5 mm3 N⁻1 m⁻1, 78.8% lower than the SiC-free coating. The dominant wear mechanism changed from abrasive/adhesive wear to a synergistic mode dominated by hard-phase reinforcement and oxide film protection. These results show that adjusting SiC content effectively improves the hardness and wear resistance of laser-clad Ni45 coatings on 316L stainless steel.