Abstract:The NiCrBSi-Y₂O₃ composite coatings were prepared on the surface of 45 carbon steel by plasma spray, the microstructure and tribological properties of the coatings were investigated. The results show that the NiCrBSi-Y₂O₃ composite coatings are mainly composed of γ-Ni, CrB, Cr₇C₃ and Y₂O₃. With addition of Y₂O₃, hard phases such as CrB, Cr₇C₃ emerge in composite coating, and the density of the composite coatings also increases. The NiCrBSi-0.5Y₂O₃ composite coating presents excellent tribological properties. Its friction coefficient is 0.175, which is about 37% of that of the pure NiCrBSi coating. The mass wear loss is 1.2 mg, which is reduced by 43% compared with the pure NiCrBSi coating. When the loads are 6-10 N, the NiCrBSi-0.5Y₂O₃ composite coating suffers from slight wear and the wear mechanisms are mainly adhesive wear accompany with slight micro-cutting wear and micro-fracture wear. As the load increases to 12 N, the wear mechanisms are adhesive wear and severe micro-cutting wear.

Key words: plasma spray; composite coating; NiCrBSi; Y₂O₃; friction; wear