Unveiling the influence of TiN on the microstructure and high-temperature oxidation behavior of Ti-Al-Cr composite coating

The effect of TiN addition on the high temperature oxidation behavior of Ti-Al-Cr coating was investigated. Results revealed that the coating with 4 wt.% TiN addition exhibited superior oxidation resistance. The minimum mass gain after being oxidized at 850 ℃ was 0.56 mg/cm2, which was 40.1% less than that of the TiN-free coating. The mechanisms for TiN addition can enhance the high-temperature oxidation resistance of Ti-Al-Cr coating include the dispersed TiN resulting in more grain boundaries and prolonging the diffusion paths of oxygen and contributing to the generation of a protective CrAlN layer to diminish the inward oxygen diffusion, as well as facilitating the formation of the dense internal oxide layer Al2O3 and Cr2O3.