Sol–gel titania films on YHfAl foils and their influence on inhibition of transition aluminas during oxidation at high temperatures

Abstract

In this experimental work, sol–gel technique was used as surface coating of YHfAl alloys to avoid the formation of transition aluminas (δ and θ). This technique has an advantage of low cost and rapidity. The preparation conditions of TiO2 sol–gel coatings were presented with a description of their evolution with temperature during the first stages of YHfAl oxidation. It is noted that the rutile is the only detected phase at 800°C. The sol–gel thin films were prepared in order to inhibit the formation of transition aluminas. An important gain mass was recorded at a temperature of 875°C and the first grains of aluminas were appeared after 0.5h of oxidation. A sol–gel TiO2 film of nearly 60nm thick has proven its efficiency and has allowed to reduce the presence of transition aluminas.