High temperature oxidation resistance of multicomponent Cr–Ti–Al–Si–N coatings

Abstract

Nanosrystalline CrAlSiN and CrTiAlSiN coatings were deposited by using a cathodic-arc deposition system with lateral rotating arc cathodes. Titanium, chromium and Al 89Si 11 cathodes were used for the deposition of CrAlSiN and CrTiAlSiN coatings. For the high temperature oxidation test, the coated samples were annealed at 900 °C in air for 2 h. The oxidation characteristics of the deposited coatings were also studied by thermal-gravimetric analysis (TGA). In this study, chemical composition and bonding states of the deposited and annealed CrAlSiN and CrTiAlSiN coatings were evaluated by X-ray photoelectron spectroscopy (XPS). All the deposited Cr 0.36Al 0.57Si 0.07N and Cr 0.40Ti 0.22Al 0.36Si 0.02N coatings showed B1-NaCl crystal structure and possessed nano-grain sizes of 8–12 nm. The oxide scale formed on the Cr 0.40Ti 0.22Al 0.36Si 0.02N coatings consisted of major TiO 2 at the surface region, followed by a mixed layer of Al 2O 3 and Cr 2O 3 phases. TiO 2 grew at an accelerated rate on to the aluminum and chromium oxide layers after oxidation at 900 °C. The oxidation rate of the Cr 0.36Al 0.57Si 0.07N coated sample was much lower than that of Cr 0.40Ti 0.22Al 0.36Si 0.02N. A dense protective layer, mainly consisted of Al 2O 3 and Cr 2O 3, retarded the diffusion of oxygen into Cr 0.36Al 0.57Si 0.07N. It indicated that Cr 0.36Al 0.57Si 0.07N with higher Al, and Si contents possessed superior oxidation resistance than Cr 0.40Ti 0.22Al 0.36Si 0.02N.