| Popis: |
Nonporous anodic aluminum oxide films were potentiostatically formed at 30V and subsequently exposed to neutral aqueous ammonium tartrate for 3000 min at 30V, 10V, and at rest potential. Porous film growth was observed at the formation potential in accordance with Part I . Some factors responsible for the observed stability of the film capacitance and resistance at 30V have been determined by modeling the porous film as a parallel combination of two parallel RC circuits. Films tested at 10V thinned slowly by the development of a large number of fine pores at the oxide/electrolyte interface; in addition, pore colonies were observed in the metallic substrate below the thinning film. At rest potential the film developed a nonporous cellular topography, presumably an artifact of a selective dissolution process. The film capacitance at 10V and rest potential has been expressed as film thickness vs. time profiles under the assumption of uniform thinning. |
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