Study of the oxidation mechanism at high temperature of nanofiber textured AlTiCrN coatings produced by physical vapor deposition using high-resolution characterization techniques

AlTiN coatings with a NaCl structure have onset point of oxidation around 850 °C. To withstand oxidation above 850 °C, we studied the influence of Cr addition on the structure, mechanical properties and oxidation resistance of different AlTiCrN coatings. The structural evolution during the annealing of the AlTiCrN coating was revealing that all coatings kept the NaCl structure up to 950 °C. The oxidized coatings shown that the addition of Cr promoted the formation of a TiO2 layer over a gradient CrAl2O3 layer. This last layer is very rich in aluminum under the TiO2 layer and richer in chromium at the nitride-oxide interphase.