The sputter-deposited Cr-Ta alloys show extremely high corrosion resistance in 12 M HCl. The open circuit potentials of the Cr-Ta alloys are located in the passive regions of both chromium and tantalum, and all Cr-Ta alloys are spontaneously passivated. XPS analysis indicates that the composition and thickness of the air-formed film are the same as those of spontaneously passivated film, and the composition of the passive films becomes constant after prolonged immersion. The film consists of a double oxyhydroxide of chromium and tantalum cations. The formation of the homogeneous double oxyhydroxide film consisting of both chromium and tantalum cations by air oxidation is responsible for the extremely high corrosion resistance of the Cr-Ta alloys in comparison with the corrosion resistance of chromium and tantalum metals.
ASJC Scopus subject areas
- 化学 (全般)