Abstract
Aluminum of 99.99% in purity was anodized in aqueous solutions of sulfuric, oxalic, and chromic acids. The behavior of the dissolution of these anodic oxide films dipped in sulfuric and various organic acids was examined. The relation between these results and the bath voltage during the anodizing in these acids was discussed.
The results obtained were as follows.
1) Among the acids of the same series, the dissolution rate of the film was higher and the bath voltage was lower when pka and pH of the acid were lower. However, among acids of different series, the dissolution rate could not be presumed from pka and pH, and the degree of bath voltage also could not be presumed from the dissolution rate.
2) It was known that the dissolution rate of anodic oxide films was not controlled by diffusion process, but by activation process.
