Self-healing Corrosion Protection Ability of Composition-Gradient Al 2O3·Nb Nanocomposite Thin Films

Mika Yasuda, Noboru Akao, Nobuyoshi Hara, Katsuhisa Sugimoto

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


Al2O3·Nb nanocomposite thin films have been known as films having self-healing corrosion protection ability. To attain high self-healing ability and low pinhole defect density, the optimization of composition and structure of the films has been examined. The films were prepared on an Fe thin film substrate on a glass slide using ion beam sputter deposition technique. The self-healing ability of the films was evaluated by the repassivation behavior of potential and current of specimens coupled with an Au auxiliary electrode just after scratching by a knife edge in 0.1 M NaCl. Microscopic observation showed that the pinhole defect density increased with increasing Nb content. Therefore, to use the films as corrosion-protection coatings, decreasing Nb content would be needed for decreasing pinhole defect density but increasing Nb content for increasing self-healing ability. To solve this contradiction, composition-gradient Al2O3· Nb films were introduced. The composition-gradient film with increasing Nb content from the film surface to the substrate interface showed low pinhole defect density and high self-healing ability. A three-layer film of Al 2O3 (outer)/composition-gradient Al2O 3 · Nb (middle)/Nb (inner) gave the best result.

Original languageEnglish
Pages (from-to)B481-B487
JournalJournal of the Electrochemical Society
Issue number10
Publication statusPublished - 2003 Oct


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