Effect of N content on the microstructure, mechanical properties and high temperature oxidation behavior of TiAlN coating prepared by FCVA

To overcome the poor corrosion and oxidation resistance of hydraulic cylinder piston rods, titanium aluminum nitride (TiAlN) coatings were prepared using filter cathode vacuum arc (FCVA) technology as a surface protection strategy. The optimization and regulatory mechanism of nitrogen content on the microstructure, mechanical properties, and high-temperature oxidation behavior of the coatings was emphasized. The results indicated that with increasing nitrogen content from 20 to 50 at.%, the coatings exhibited a dense and uniform microstructure with promoted fcc TiAlN (111) preferred orientation. The hardness and elastic modulus of the coating gradually increased due to solid-solution strengthening and lattice distortion. The H/E and H 3 /E 2 values increased with the increase of nitrogen content, indicating an enhanced ability to resist plastic deformation. Meanwhile, the adhesion strength also increased progressively with nitrogen content. Higher nitrogen content improved the coating's antioxidant performance, especially at high levels. The oxide scale evolved from a loose Al 2 O 3 /rutile TiO 2 double layer with poor protectiveness to a dense Al 2 O 3 /anatase TiO 2 passivation layer, and the oxidation mechanism shifts from outward Al diffusion to a diffusion blocking mode at high nitrogen content (≥40 at.%). This study contributes to a deeper understanding of the regulation of nitrogen content on the structure and properties of TiAlN coatings, providing key guidance for coating design in harsh environments.