Crystal structure and tribological properties of Zr[sbnd]Al[sbnd]Mo[sbnd]N composite films deposited by magnetron sputtering

Abstract

Quaternary zirconium aluminum molybdenum nitride (ZrAlMoN) composite films with different molybdenum content were deposited using reactive magnetron sputtering. The results showed that the films at <6.7 at.% molybdenum exhibited a single face center cubic (fcc) ZrN phase, while further incorporation of molybdenum led the film to exhibit a dual phase of fcc-ZrN and fcc-Mo2N. ZrAlMoN films’ room temperature friction coefficient decreased gradually due to the lubricant molybdenum and the formation of Mo2N phase in the film at > 6.7 at.% molybdenum. The room temperature wear rate first maintained its value of ∼3.5 × 10−7 mm−3 N−1 mm−1 at 0–8.6 at.% molybdenum and then dropped to ∼5.0 × 10−8 mm−3 N−1 mm−1 at 12.6 at.% molybdenum, while further increasing in molybdenum content results in the increase of wear rate. The roughness of the film and the appearance of fcc-Mo2N phase were considered as the main factors of the wear rate. For the tribological properties of the film at 13.8 at.% molybdenum, the increase in temperature could induce the main wear mechanism changing to oxidation wear. The change in the wear mechanism resulted in the decreasing in the wear rate as well as also led to the friction coefficient increased at first from RT to 500 °C and then started decreasing at further elevated temperature.