Improvement In The Oxidation Resistance Of A γ-tial-based Alloy By Sol-gel Derived Al_2o_3 Film

摘要

Sol-gel thin film offers a number of advantages that makes it an attractive method for obtaining coatings on alloy. In this paper, an Al_2O_3 film was deposited on a γ-TiAl-based alloy from aluminum isopropoxide (Al(OC_3H_7)_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 ℃ were performed to test its effect on the oxidation behavior of the alloy. The Al_2O_3 film exhibited beneficial effects on the oxidation resistance of the alloy. The oxidation rate of the Al_2O_3 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 Al_2O_3 film, a mixture layer of rutile TiO_2 and α-Al_2O_3 occurred, but more α-Al_2O_3 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.