Method of manufacturing electrode foil for aluminium electrolytic

Abstract

For this invention it is disclosed that aluminium electrode foil is caused to pass through any of nitric acid, sulfuric acid and mixed acid thereof each added with at least one selected from the group consisting of chromic acid, oxalic acid, citric acid, phosphoric acid, boric acid, succinic acid and malonic acid as an additive and electrically etched in the etching process of a final stage for increasing the diameter of pits created in a preceding stage for etching to a diameter suitable for a forming voltage, and any of the nitric acid, sulfuric acid and mixed acid thereof controls the concentration of dissolved aluminium to 5 to 25 g/l, whereby aluminium is dissolved along the inner wall of the pits while the surface dissolution of the aluminium electrode foil is suppressed, so that the diameter of the pits can be effectively increased.