Microstructures and properties of in-situ TiC particles reinforced Ni-based composite coatings prepared by plasma spray welding

In this investigation, the in-situ TiC particles reinforced Ni-based composite coatings were produced by plasma spray welding with mixed powders (NiCrBSi+Ti+NiCr–Cr3C2). Their microstructures and properties were studied. The experimental results showed that the composite coatings consisted mainly of γ-Ni, Cr23C6, Cr7C3, Ni3Si, Cr5B3, CrB, FeNi3 and TiC phases. TiC particles were in-situ synthesized during plasma spray welding. The content of TiC particles and chromium carbides in the coatings increased with the mass fractions of Ti and NiCr–Cr3C2 powders increasing in the mixed powders, which resulted in enhancing the composite coatings hardness. The composite coating prepared with the mixed powder (70 wt%NiCrBSi+30 wt% (Ti+NiCr–Cr3C2)) showed a higher hardness 1142 HV0.5. The wear resistance of the composite coatings were greatly improved due to the presence of in-situ TiC particles in comparison with the substrate. When the mixed powder (75 wt%NiCrBSi+25 wt% (Ti+NiCr–Cr3C2)) was used, the composite coating had better wear resistance, and the coating wear volume loss after wear tests was 6 mm3, which was only 5% of that for the low carbon steel substrate (125 mm3).