Oxidation behavior at 1100 C of NiCrAlY coatings deposited by various PVD techniques

NiCrAlY has been widely used as a protective layer on gas turbine engine hot section components and can be synthesized by different physical vapor deposition techniques. Here, the oxidation behaviors of arc-evaporated, magnetron-sputtered, and hybrid arc/sputtering NiCrAlY coatings were investigated. Preparation techniques can significantly affect the oxidation behavior of NiCrAlY coatings by adjusting the Al content. Arc-evaporated NiCrAlY coating has the lowest resistance against oxidation at 1100 degrees C, forming a bi-layered scale with outer spinel-rich and inner alumina-rich oxides. In comparison, the other two NiCrAlY coatings with higher Al content were oxidized to form dense scales enriched in alpha-Al2O3 after 250 h of oxidation. Furthermore, the outward diffusion of Mn from Hastelloy X promotes the production of spinel oxides, which accelerates the oxidation process.