Effects of Ta content on the oxidation and high-temperature tribological behaviors of (Zr, Ta) N coating deposited by double-cathode glow plasma alloy

Abstract ZrN-based coatings have attracted significant attention due to their high hardness and outstanding thermal properties. In this research, ZrN, TaN, and (Zr, Ta) N coatings with different Ta content (ZrTaN-1 coating with 30 at.% Ta content and ZrTaN-2 coating with 60 at.% Ta content) were prepared with a double-cathode glow plasma alloy (DGPA). The influence of Ta content on the phase composition, microstructure, mechanical performance, oxidation and tribological behaviour of the coatings was comparatively studied. The results illustrated that the (Zr, Ta) N coatings with different Ta content crystallized in NaCl-type structures. The lattice constants of the (Zr, Ta) N coatings decreased with increasing Ta content because the Ta–N bonds (0.227 nm) were shorter than the Zr–N (0.230 nm) bonds, which confirmed that Zr was successfully substituted with Ta. The oxidation resistivity of the (Zr, Ta) N coatings exhibited minimum mass gain values of 0.55 mg/cm2, 5.12 mg/cm2, and 17.08 mg/cm2 at 650~850 °C with a Ta content of 60 at.%. The addition of Ta effectively reduced the thermal stress of the coatings and avoided cracking and peeling at high temperatures. In addition, high-temperature tribological experiments showed that the wear rate of the (Zr, Ta) N coatings at 500 °C was low and stable and was only 32.9% of that of the ZrN coating under the same conditions. This was attributed to the formation of a dense (Zr, Ta)-rich oxide on the coating surface.