Development of Si-modified CrAlSiN nanocomposite coating for anti-wear application in extreme environment

• The friction coefficient of CrAlSiN films increased with increasing Si content.
• The friction coefficient decreased with increasing testing temperature.
• CrAlSiN films exhibited superior wear resistance at high temperature.
• The wear rate of CrAlSiN films is dependent on resistance to plastic deformation.

(Cr0.5Al0.5)1 − xSixN coatings with Si contents from 0 at.% to 11.5 at.% were deposited on Inconel 718 substrates by RF magnetron co-sputtering. In the ball-on-disc wear tests, the increased friction coefficient of (Cr0.5Al0.5)1 − xSixN coatings with increasing Si content at high temperature was revealed, owing to the occurrence of tribochemical reaction which is verified through XPS analysis. The hardness (H) and the reduced elastic modulus (E*) of (Cr0.5Al0.5)1 − xSixN coatings were acquired by a nanoindentation. The calculated yield pressure of (Cr0.5Al0.5)1 − xSixN coatings was proportional to the wear resistance of coatings at ultra-high temperature(500 °C, 850 °C and 950 °C). (Cr0.5Al0.5)1 − xSixN coating with maximum yield pressure as high as 8336 nm2 by adding 9.0 at.% Si exhibited superior resistance to plastic deformation and wear. Moreover, the formation of protective third-layer on the surface resulted in the extremely low wear rate at 850 °C and 950 °C. On the basis of these improved tribological behaviors, the superior durability of (Cr0.5Al0.5)1 − xSixN coating is thus demonstrated.