PROCESS FOR ANODIZING ALUMINUM FOIL

摘要

PROCESS FOR ANODIZING ALUMINUM FOIL In an integrated process for anodization of aluminum foil for electrolytic capacitors, aluminum foil having a hydrous oxide layer is electrochemically anodized in an aqueous solution of boric acid and 2 to 50 ppm phosphate having a pH of 4.0 to 6.0. The anodization is interrupted for stabilization by passing the foil through a bath containing a borax solution having a pH of 8.5 to 9.5 and a temperature above 80.degree.C. The foil is reanodized in the boric acid-phosphate solution after the stabilization. The process is useful in anodizing foil to a voltage of up to 760V.