Oxidation behaviour of a CoNiCrAlY/h-BN based abradable coating

The oxidation resistance of a thermally sprayed CoNiCrAlY/h-BN abradable coating was studied at 750 and 900 °C. First, the high porosity of the abradable coating was carefully characterised in order to estimate the specific surface area of the coating, required to evaluate the oxidation kinetics. Then the formed oxides were investigated by XRD, Raman spectroscopy and SEM. At 900 °C, the mass variations exhibited a deviation from parabolic behaviour due to rapidly growing oxides. Meanwhile, at 750 °C, after a transient state, the oxidation rate reaches a steady state, indicating that a protective alumina scale was maintained at this temperature.