Enhancement of oxidation resistance of zirconium alloy with anodic nanoporous oxide layer in high-temperature air/steam environments

Highly-ordered and hexagonally close-packed nanoporous zirconium oxide layer is formed on the surface of zirconium alloy by anodization, and the anti-oxidation behavior of the zirconium alloy with the nanoporous oxide layer has been investigated. The oxidation experiments were carried out in both air and steam environments at 1000 °C. Interestingly, zirconium alloy with the nanoporous oxide layer exhibits dramatic improvement in the oxidation resistance compared to bare zirconium alloy without the nanoporous oxide layer. Analysis using several characterization tools reveals that large single-crystalline columnar zirconium oxide grains are formed beneath the nanoporous oxide layer and these grains prevent further oxidation.