High-temperature oxidation of FeCrAl alloy with alumina–silica–ceria coatings deposited by sol–gel method

One-layer protective coatings made up of SiO2–Al2O3 or SiO2–Al2O3–CeO2 oxides were synthesized on a FeCrAl alloy substrate by the sol–gel method from sols containing tetraethyl orthosilicate, aluminum tri-sec-butoxide and cerium(III) 2,4-pentanedionate as the precursors. Coating solutions with the Si:Al:Ce molar ratio of 3:1:0, 3:1:0.1; 3:1:0.01, and 3:1:0.001 were used. The composition and morphology of the obtained gels were examined by TG/DSC, XRD, and SEM techniques. It was found that a small addition of cerium affected the morphology of the forming coatings and improved the FeCrAl alloy resistance to high-temperature oxidation (in air at T = 900 °C for t = 100 h). The oxidation of all the investigated samples conformed to the parabolic rate. The protection effectiveness of the one-layer coatings after 100 h of high-temperature oxidation was as high as 70 %.