Oxidation Behavior of Plasma Sprayed CoNiCrAlY/YSZ Film at 1173 and 1273 K in Air

摘要

A CoNiCrAlY/YSZ(ZrO_2-8 mol percent Y_2O_3) film prepared by low-pressure and air plasma spraying was oxidized in air at 1173 K for up to 3240 ks . Thickness and concentration profiles across oxide scales and Al depleted zone with disappearing #beta# -NiAl phase were measured for both the CoNiCrAlY/YSZ interface and the CoNiCrAlY surface by using an electron probe micro-analysis. The oxide layer at the interface was Al-rich oxide containing Co, Ni, and Cr in addition to Y, while the oxide at the surface consisted of pure Al_2O_3, except for that it contains Y at the alloy side. The former grew three times thicker than the latter. A ratio of thickness between the Al depleted zone and the oxide layer ranged from 3 at 1173 K to 4 at 1273 K. Concentration profiles of each element measured across the Al depleted zone were almost flat, except for that at the interface oxidized at 1173 K, where Al and Ni concentrations decreased towards the Al-rich oxide layer, whereas Co and Cr concentrations increased.