Effect of Al₂O₃-Ce₂O₃ Composite Film on High Temperature Oxidation Resistance of 304 Stainless Steel

In order to improve the high temperature oxidation resistance of 304 stainless steel， Al2O3 thin films and Al2O3-Ce2O3 composite films were respectively prepared on the surface of 304 stainless steel by sol-gel method using aluminum isopropyl alcohol and CeCl3·7H2O as raw materials.The effect of Al2O3-Ce2O3 composite films with different Ce/Al ratios (molar ratios， the same below) on the high-temperature oxidation resistance of 304 stainless steel at 900 ℃was studied through oxidation kinetics curves， XRD， SEM， and EDS analysis.Results showed that the weight gain and spalling values of the Al2O3-Ce2O3 film coated with Ce ∶Al ＝1 ∶10 were only 34.1%and 51.8%of those of the uncoated steel after cyclic oxidation at 900 ℃for 100 h， showing the optimal high temperature oxidation resistance.The Al2 O3-Ce2 O3 composite film reduced the oxygen partial pressure on the substrate surface of 304 stainless steel， which facilitated the formation of a protective Cr2O3 oxide layer and effectively suppressed the volatilization of Cr2O3.Furthermore， the addition of Ce2O3 reduced the thermal stress in the oxide scale and improved its adhesion to the substrate.Ce2O3 played an active element effect and changed the growth mechanism of oxide scale，so the high temperature oxidation resistance of composite film was significantly improved.