低濃度KOH溶液中におけるアルミニウムアノード酸化皮膜の生成挙動 [in Japanese] Formation of Anodic Oxide Films on Aluminum in Diluted KOH Solutions [in Japanese]
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Aluminum was anodized in diluted KOH solutions galvanostatically to examine the effect of KOH-concentration on the growth and breakdown of anodic oxide films. Time-variations in the anode potential, <i>E<sub>a</sub></i>, the amount of dissolved Al<sup>3+</sup> ions, and electroluminescence intensity were measured during anodizing, and the film structure was observed by transmission electron microscopy and scanning electron microscopy.<br>At 5×10<sup>-5</sup> and 5×10<sup>-4</sup>M, <i>E<sub>a</sub></i> increased with time linearly at the initial stage, and the rate of increase in <i>E<sub>a</sub></i> decreased at 400V. The slow increase in <i>E<sub>a</sub></i> stopped at about 600V, and beyond the potential <i>E<sub>a</sub></i> increased at a high rate until the film breakdown started at 1600V and 1100V in 5×10<sup>-5</sup> and 5×10<sup>-4</sup> M solution, respectively. In both solutions, the growth of the oxide film was accompanied by the formation and growth of relatively large voids between 400V and 600V, and beyond 600V small numerous voids developed on the entire surface. The film growth can be explained by the local oxide dissolution and precipitation of hydroxide.<br>At 5×10<sup>-3</sup> M, <i>E<sub>a</sub></i> remained zero for the initial 1500s of anodizing, and then increased linearly with time before film breakdown started at 600V. The anodic oxide films consisted of two layers: an outer porous layer and an inner dense layer.
- Journal of The Surface Finishing Society of Japan
Journal of The Surface Finishing Society of Japan 53(2), 134-141, 2002-02-01
The Surface Finishing Society of Japan