Microstructures and Properties of Plasma Sprayed Ni Based Coatings Reinforced by TiN/C _{1- x} N _x Ti Generated from In-Situ Solid-Gas Reaction

Abstract

The strengthening hard phases TiN/C _{1- x} N _x Ti were generated by in-situ solid-gas reaction in Ni-based composite coatings prepared using a plasma spray welding process to reinforce the wear resistance of the coatings. The microstructures and properties of the coatings were investigated. The results showed that the coatings mainly consisted of phases such as TiN, C _{1- x} N _x Ti, TiC, etc. A small amount of CrB, M ₇C ₃, and M ₂₃C ₆ were also detected in the coatings by micro-analysis method. Compared with the originally pure NiCrBSi coatings, the hardness of the NiCrBSi coatings reinforced by in-situ solid-gas reaction was 900 HV _0.5, increased by more than 35%. Consequently, the wear resistance of the reinforced coatings was greatly improved due to the finely and uniformly dispersed hard phases mentioned above. The weight losses after wear test for the two kinds of coatings were 15 mg and 8 mg, respectively.