Transient behaviour of the anodic oxide film on tantalum

✍ Scribed by M. Kato

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 431 KB
• Volume: 21
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(76)85155-9

✦ Synopsis

Ahstract

-After heating the anodic oxide tilm on tantalum, a constant current or voltage was applied to the specimen in a diluted phosphoric acid solution. and the transient behaviour was examined according to the Frcnkel defect model. Interstitial ions taking part in ionic conduction are captured in the vacant sites by heating. For a11 expr-csaion of this rate. the second term of Dew&l's equation (iam) was found to be valid. By using this equation it was found that the film. once deteriorated by heating, could be repaired by subsequent current flow and no more serious deterioration was observed after a second heating. When a constant voltage was applied to the specimen after heating, transferencr of ions from the normal lattice sites to interstitial ones was considered to be induced by current flow as well as by field strength, hence the current term I was incorporated in to the first term of Dewald's equation. The amended equation colnclded fairly well with the experimental results.