Effect of Powder Feeding Rate on Properties of Plasma Sprayed Mo₂NiB₂-Based Cermet Coating

Mo₂NiB₂-based cermet coating was prepared on the surface of Q235 steel substrate by atmospheric plasma spraying, and the effect of powder feeding rate (40-80 g·min^-1) on the hardness, bonding strength and corrosion resistance of Mo₂NiB₂ coating was studied. The results show that the Mo₂NiB₂ coating was mainly composed of Mo₂NiB₂ ceramic phase, MoNi₄ alloy phase and MoB₂ hard phase under different powder feeding rates, and the coating quality was the best when the powder feeding rate was 60 g·min^-1. With increasing powder feeding rate, the hardness and bonding strength of Mo₂NiB₂ coating increased first and then decreased and both reached the maximum values when the powder feeding rate was 60 g·min^-1, which were 2 107 HV and 29.23 MPa, respectively. The corrosion resistance of Mo₂NiB₂ coating increased with increasing powder feeding rate, and reached the best level when the powder feeding rate was 80 g·min^-1.