Preparation of Al2O3/ZrO2 coating by sol-gel method and its effect on high-temperature oxidation behavior of γ-TiAl based alloys

Al2O3/ZrO2 coating was deposited on gamma-TiAl based alloys with aluminum isopropoxide (Al(OC3H7)(3)) and zirconium oxychloride octahydrate (ZrOCl2 center dot 8H(2)O) as starting materials by sol-gel method. The coating synthesized using dip-coating process, was uniform and crack-free. Isothermal and cyclic oxidations of the coated and uncoated specimens at 1000 degrees C in static air were carried out to test the coating effect on the oxidation behavior of the alloy. The coating decreases the oxidation rate of the alloys and increases the cyclic oxidation resistance. The possible mechanism of the coating on the oxidation behavior of the alloy was discussed.