Degradation of air-formed films on titanium in simulated solution of bentonite contact water

Hideo Shibuya, Jigen Takahashi, Noboru Akao, Nobuyoshi Hara, Katsuhisa Sugimoto

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Titanium is thought to be one of candidate materials for an overpack container for the geological disposal of radioactive wastes in Japan. It is presumed that an overpack container will be corroded in bentonite-contact water under reductive conditions after longterm disposal. In this study, optical and compositional changes in air-formed oxide films on titanium was examined by ellipsometry and XPS analysis during and after cathodic polarization in the simulated solution of bentonite-contact water, respectively. A decrease in a refractive index was first occurred with decreasing potential among a refractive index, an attenuation coefficient and a film thickness. This was due to the reduction of Ti4+ ions to Ti3+ ions in the films. Based on the initiation potential of change in a refractive index, an oxide film formed in air with 75% RH was thought to have the highest resistance to degradation by cathodic polarization among oxide films formed in air with 35-75%RH.

Original languageEnglish
Pages (from-to)372-381
Number of pages10
JournalZairyo to Kankyo/ Corrosion Engineering
Issue number7
Publication statusPublished - 2004 Jul


  • Bentonite-contact water
  • Cathodic polarization
  • Degradation
  • Ellipsometry
  • Overpack container
  • Oxide film
  • Titanium
  • XPS


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