Two-Layer Nano-Oxide Composite Films on Fe-18Cr Alloys

A two-layer film composed of a reactive element (RE) oxide (ZrO2, Y2O3, CeO2, or La2O3) and aluminum oxide (Al2O3) was prepared on the surface of Fe-18Cr alloys by an electrochemical process combined with sintering. High-resolution field emission scanning electron microscopy (FE-SEM) was used to characterize the two-layer film, which showed nanostructure. SEM, EDS and mass gain measurement were used to study the oxidation resistance of the film on Fe-18Cr alloy. It is proved that this kind of film is effective in protecting the substrate from oxidation. The results also indicated that the two-layer film possesses superior oxidation resistance than a single Al2O3 film. The mechanisms accounting for such effects have been discussed.