High temperature oxidation resistance and oxidation mechanism of FeNiCrAl/Cr₃C₂ composite coating deposited by high velocity arc spraying

FeNiCrAl/Cr₃C₂ metal-ceramic composite coating was prepared on the 45 steel by high velocity arc spraying process. The oxidation kinetic curves of the coating was measured at 750℃ for 200 h. Optical microscopy, scanning electron microscopy, and X-ray diffraction were used to analyze the microstructures and the oxidation products of the coating. The high temperature oxidation mechanism was discussed. The results show that the oxidation kinetic curves of the coatings followed a parabolic law. The weight gain of the FeNiCrAl/Cr₃C₂ coating is much lower than that of the 20G steel. The high Ni content FeNiCrAl/Cr₃C₂ coating shows much better oxidation resistance than that of the other. The oxidation products can block the oxygen diffusion channel to protect the coating.