Study on the tribological properties of AlN/AlCrN composite coatings on the surface of TA15 alloy

To address the dual challenges of poor adhesion and insufficient high-temperature wear resistance of protective coatings on TA15 titanium alloy, this study proposes a tailored AlN/AlCrN composite coating design. The coatings were fabricated via reactive magnetron sputtering with an optimized AlN transition layer. This architecture resulted in a dense columnar structure, significantly enhancing the surface properties. The composite coating achieved an average hardness of 29.87 GPa—three times that of the substrate—and an interfacial bonding strength of 44.17 ± 1.85 MPa, a 16.6 % increase over a single AlCrN layer. More importantly, the coating exhibited exceptional tribological stability across a wide temperature range. Under a 300 g load at room temperature, the friction coefficient dropped to 0.28 (46 % lower than the substrate), and the wear rate decreased by 73 %. Remarkably, at 600°C, the friction coefficient further reduced to 0.21, with the wear rate being only one-sixth of the substrate, which is attributed to the in-situ formation of a lubricious Al/Cr-rich oxide layer. This work provides an effective surface modification strategy, broadening the application horizon of TA15 alloy under extreme conditions.