Abstract
The thickness, morphology, chemical composition, and crystallinity of the anodized film formed on aluminum were examined in a transmission electron microscope (TEM). Thin foil for TEM analysis was prepared by ultramicrotomy. The relationship between the microstructure and the electrochemical characteristics of the alumina film forming on the pure aluminum was discussed in this investigation. At the forming voltage less than 100V, the anodized films formed at 85 ℃in aqueous ammonium adipate electrolyte was amorphous in nature. Although the film resistance was increased with the forming voltage, its dielectric constant was not changed significantly. As the forming voltage exceeded 100V, crystalline γ′_Al2O3 was present in the film. The amount of crystalline γ′_Al2O3 and the flaws accompanied with the crystallization process were found to increase with the forming voltage. The crystalline alumina seemed to be beneficial in raising the dielectric constant of the oxide film. As the forming voltage reached 200V, the oxide film was composed of an inner amorphous layer and an outer crystalline γ′_Al2O3 layer. The crystalline layer had a lower resistance but a higher dielectric constant than the amorphous layer.
Publication Date
2003-05-28
Online Available Date
2003-05-28
Revised Date
2003-05-28
Received Date
2003-05-28
Recommended Citation
Jeng-Kuei Chang, Chi-Min Liao, Chih-Hsiung Chen, Wen-Ta Tsai.
Microstructure and Electrochemical Characteristics of the Anodic Film Formed on Aluminum Surface[J]. Journal of Electrochemistry,
2003
,
9(2): 139-146.
DOI: 10.61558/2993-074X.1497
Available at:
https://jelectrochem.xmu.edu.cn/journal/vol9/iss2/4
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