Effect of Heat Treatment on CO2 Corrosion Resistance of Ni-based Alloy Coating on N80 Steel

Ni-based alloy coating was made on N80 steel substrate by plasma arc spraying, and then high temperature diffusion process was performed. The CO2 corrosion properties of the Ni-based alloy coating in simulated oil field environment were tested. The microstructure and phase constituents of the coating were analyzed by SEM, EDX and XRD. The results show that the phase constituents of the Ni-based alloy coating were Ni, Cr1.2Ni2.88, FeNi3、MoO2 and CuO. After heat treatment at 600 ℃ for 1 h, the coating was denser. The CO2 corrosion rate of the coating after heat treatment was 0.0046 mm/a, and was about 1/100 of the coating before heat treatment. The coating after heat treatment had excellent CO2 corrosion resistance.