Abstract
In the present study, the role of aluminide coating on oxidation resistance of Ni-based single crystal superalloy was studied at 900 degrees C. The oxidation kinetics curves obey the parabolic law in both conditions. However, the significant difference was found after 100 h oxidation in both conditions. The coated specimens showed a better oxidation resistance than the uncoated ones. This is due to the phase transformation occurred from theta-Al2O3 to alpha-Al2O3 in the coated specimens with increasing oxidation time but not in the uncoated ones. The production of more alpha-Al2O3 during oxidation is expected since alpha-Al2O3 acts as a protective layer against oxidation due to its stability at high temperatures. It could be also recognized from the surface morphology of the oxidized coated specimen after 500 h oxidation.