High-temperature oxidation of nano-multilayered TiAlCrSiN thin films in air

Nano-multilayered TiAlCrSiN films consisting of alternating, crystalline TiCrN and AlSiN nanolayers were deposited by cathodic arc plasma deposition. Their oxidation characteristics were studied between 600 and 1000 °C for up to 70 h in air. The formed oxides consisted primarily of Cr2O3, α-Al2O3, SiO2, and rutile-TiO2. The TiAlCrSiN films oxidized slower than the TiN films and faster than the CrN or CrAlSiN films, with an apparent activation energy of 36.4 kJ/mol. During their oxidation, an outermost TiO2 layer was formed by outward diffusion of Ti ions, and the outer Al2O3 layer was formed by outward diffusion of Al ions. Simultaneously, an inner (Al2O3, Cr2O3)-mixed layer and an innermost TiO2 layer were formed by the inward diffusion of oxygen ions. SiO2 was present mainly in the lower part of the oxide layer due to its immobility.