Growth of Anodic films on valve metals

✍ Scribed by T. Hurlen; E. Gulbrandsen

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 392 KB
• Volume: 39
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/s0013-4686(94)85069-0

✦ Synopsis

Ahstraet

-By analysis of transport number and F-log j data for valve metals under galvanostatic anodization, obedience is found to the kink dependent Cabrera-Mott equation for irreversible transfer of metal ions from metal to oxide and to the defect dependent high-field ion migration equation for transport of both metal and oxygen ions in the growing anodic film. For Al, the kink and defect dependences are d log s/d log j = 0.5 and d log N/d log j approaching 0.67 at low current densities (oxygen ion transport) and 0.5 at high ones (metal ion transport), and the ion transfer valence is n = 3. The denser is the oxygen packing in the oxide, the higher is the electric field needed to drive a given ionic current through it.