Abstract
Effects of hydroxide on the film thickness and properties of anodized films have been investigated from V-T curves and measurments of pH on the anode. The results obtained were as follows:
(1) The oxide films formed in alkaline solutions (sodium hydroxide, sodium phosphate, and sodium fluoride) in the presence of hydrogen peroxide were thicker than those formed in alkaline basic solutions.
(2) From the measurements of pH and V-T curves, hydrogen peroxide seemed to be dissociated as follows. H2O2→H++HO2-, HO2-→H++O22-
(3) Anodizing of aluminum-iron composite sheet (the area ratio of Al:Fe=100:1) in sodium hydroxide bath involving hydrogen peroxide provided thick and uniform films.
(4) It was found that the oxide films formed in the alkaline hydrogen peroxide bath had better properties, with regard to alkali resistance and scratch hardness, than those formed in the bath without hydrogen peroxide.
