塩酸溶液中の三角波交流エッチングによる高純度アルミニウム箔の拡面化におよぼすアノード電流波形の影響

概要

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The ac etching process on high purity aluminum foil used in electrodes for electrolytic capacitors was investigated in 3.6wt% hydrochloric acid solution at 303K and 323K by applying an asymmetrical triangular current of 0.3A/cm2 with 5Hz. The time at the top of the current form of the anodic half cycle, tp, was varied in the range of 0 to 0.1s. Etching products developed on the etching cell during the process were characterized by SEM, XPS and gravimetric analysis. The etched layer contained the products of a duplex structure, consisting of an inner anodic film of Al2O3 and an outer hydrous oxide layer of Al2O3·1.6H2O, which was formed at all tp at 303K and the tp range of 0.075~0.1s at 323K, while no etched layer was observed at tp ≤0.05s at 323K, except for only a thin film of Al2O3. It seems to be that the variation of tp affects the concentration gradient of chloride ions in the vicinity of the aluminum electrode and results in the change of the specific surface area of aluminum, and tp also affects the concentration of the aluminum hydroxide deposited on the electrode during the cathodic half cycle.
2004-07-01