EFFECT OF Al~(+3) CONCENTRATION ON AC ETCHING BEHAVIORS OF HIGH PURITY ALUMINUM PLAIN FOILS IN HYDROCHLORIC ACID ELECTROLYTES

摘要

A study has been made of the effect of Al~(+3) concentration in etching bath on morphology of the AC etched layers of high purity aluminum foils. The films etched at high aluminum ion concentrations are macro-thinned, whereas low aluminum ion concentrations give rise to very inhomogeneous etching. Layers etched at optimum concentrations of aluminum ion are deep and homogeneous, resulting in high capacitance when anodized. The corrosion potential for aluminum dissolution and the breakdown potential of oxide films increase with increasing aluminum ion concentration. The double layer capacitance obtained from impedance data can be used as the qualitative measure of the surface area of aluminum foil. Based on these results, a model for etching behavior at various aluminum concentrations has been suggested.