Electro-codeposition of Al2O3–Y2O3 composite thin film coatings and their high-temperature oxidation resistance on γ-TiAl alloy

In this paper, electro-codeposition based on electrophoretic deposition and electrolytic deposition was developed to prepare Al2O3–Y2O3 composite thin film coatings on a γ-TiAl based alloy. Scanning electron microscope observations showed that the Al2O3–Y2O3 composite coatings were very compact and consisted of uniform nano-particles after microwave sintering. Cyclic oxidation at 900 °C indicated that the Al2O3–Y2O3 composite thin film coatings improved the oxidation and scale spallation resistance of the γ-TiAl alloy significantly. The superior oxidation and spallation resistance of the coatings were attributed to the suppression of outward diffusion of Ti and Al and inward diffusion of O, the promoted selective oxidation of Al in the γ-TiAl alloy, and the improved adhesion of oxide scale induced by the Al2O3–Y2O3 composite thin film coatings.