Improvement in the oxidation resistance of a γ-TiAl-based alloy by sol-gel derived Al2O3 film

Sol-gel thin film offers a number of advantages that makes it an attractive method for obtaining coatings on alloy. In this paper, an Al2O3 film was deposited on a γ-TiAl-based alloy from aluminum isopropoxide (Al(OC3H7)3) as precursor. The thin film synthesized using a dip-coating process, was uniform and crack-free. Isothermal and cyclic oxidations of the coated and uncoated specimens at 1000 °C were performed to test its effect on the oxidation behavior of the alloy. The Al2O3 film exhibited beneficial effects on the oxidation resistance of the alloy. The oxidation rate of the Al2O3 coated specimens was much slower than that of the blank alloy. The oxide scales formed on the uncoated specimens were stratified. For the coated samples, beneath the Al2O3 film, a mixture layer of rutile TiO2 and α-Al2O3 occurred, but more α-Al2O3 formed on the coated specimens than that on the blank ones. The possible mechanism of the thin film on the oxidation behavior of the alloy was discussed.