Improving high-temperature tribological characteristics on nanocomposite CrAlSiN coating by Mo doping

Recently, nanocomposite coatings have been widely used for protective coatings at high temperature owing to the superior mechanical strength over a broad operating temperature. However, there is still room for improvement on lubricating behavior of the coatings. Molybdenum is a promising candidate to further enhance the lubricating properties because of the layer crystal feature oxide. Therefore, this study attempts to investigate the influence of Mo assisting in mechanical and tribological properties. The Mo doped CrAlSiN coatings were deposited onto Inconel alloy 718 by radio frequency reactive magnetron co-sputtering. The tribological properties of CrAlSiN and CrAlMoSiN coatings were evaluated at 600 °C by ball-on-disc wear test. The reduced friction coefficient of coatings with increasing Mo content was revealed. The improvement of wear resistance correlated with incorporating the formation of oxide into high-temperature tribological motion. Additionally, the parameter of the H³/E*² regarded as the indicator of plastic deformation resistance was utilized to estimate the anti-wear property. The wear rate of CrAlMo_xSiN coatings was roughly inversely related to the H³/E*² ratio and the lowest wear rate existed in the coating with Mo of 14.5 at.% contents. It was demonstrated that anti-wear and lubricating capability of the coatings at elevated temperature could be improved by doping Mo. The merit could be used to provide strong probability for designing advanced high-temperature coatings via adjusting both of mechanical strengthening and oxide modifying by beneficial elements tuning in connection with properties of interest.