Abstract
High purity aluminum foil was electrochemically etched with 50Hz rectangular alternating current and the effects of pretreatment on the morphology of the etched surface was discussed. The pit density and size observed by SEM was influenced greatly by the pretreatment conditions. Specifically when the samples were heated to 200°C or above in air after boiling in distilled water for 10min, no pits development occured. Sufficiently protective film was formed and virtually Square-wave chronopotentiometry allows the determination of an induction time which depended on current density and the pretreatment adopted. The resulting electrostatic capacitance of etched and anodized foil was increased by the addition of some amount of sulfuric acid to 10% hydrochloric acid solution except in the case of heating after boiling.
