Microstructure and wear performance of arc-deposited Ti–N–O coatings on AISI 304 stainless steel

A cathodic arc plasma deposition system (with variation of the O2/N2 flow ratio) was used to synthesize different Ti–N–O films on the AISI 304 stainless steel. The coating morphologies and structures were analyzed by using SEM, XRD, and TEM. The coating properties, such as adhesion, hardness, elastic modulus, and wear behavior, were explored to evaluate the impact of the O2/N2 flow ratio on the coating microstructure and properties. The results showed that the O2/N2 ratio properly controlled at 0.25 could produce an optimal film with a dense crystalline structure consisting of TiN, anatase-TiO2, and rutile-TiO2 phases, showing the best adhesion strength using a standardized ball indentation method, highest nano-indentation hardness (22.8 GPa), and highest elastic modulus in comparison to other coatings. AISI 304 stainless steel with the Ti–N–O coating not only reduced the friction coefficient from 0.8 to 0.35, but also remarkably improved the adhesion wear resistance.