Galvanostatic anodizing of aluminium

✍ Scribed by J. Yahalom; T.P. Hoar

• Publisher: Elsevier Science
• Year: 1970
• Tongue: English
• Weight: 422 KB
• Volume: 15
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(70)80030-5

✦ Synopsis

Anodic oxide films on pure aluminium have been produced at constant field strength by means of a galvanostatic technique, in sulphuric acid, sodium sulphate and ammonium borate solutions . When the field is sufficiently high, films formed in sulphuric acid grow similarly to films formed in neutral solutions : the forming voltage rises at a constant rate that depends on the cd ; it eventually reaches a limit at which breakdown occurs . The breakdown voltage (and corresponding film thickness) is mainly dependent upon the anion and not upon acidity : it 1s almost independent of ad, in both acid and neutral solutions .

The results are explained in terms of the introduction of anions into the oxide film and its ultimate disruption by mechanical forces when its thickness reaches a value determined by the type and amount of anion introduced .