Microstructure, oxidation and H2-permeation resistance of TiAlN films deposited by DC magnetron sputtering technique

The ternary compound TiAlN coating has been known to be superior to binary compound TiN in protecting tools, which may be damaged by high thermal load. In the present study, TiAlN coatings are deposited on stainless (AISI 316L) and carbon steel substrates by using DC sputtering technique. The structure of TiAlN coatings with different Al contents is studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results reveal that the structure evolves from the cubic B1 type of TiN to the hexagonal phase of AlN when the Al content increases from 0 to 70 at.%. The oxidation behavior of deposited TiAlN coatings with different Al concentrations are investigated at oxidation temperatures ranging from 300 to 800 °C using energy-dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis. It is concluded that the oxidation resistance is enhanced at first and then decreases with increasing Al content, the addition of 40 at.% Al leading to the best anti-oxidation effect. Coatings of same composition exhibit the best barrier performance to hydrogen permeation.