抄録
The previous papers described that the hardness and abrasion resistance of anodic oxide films on aluminum were increased by heat-and chemical treatments after their formation.
This paper describes the experiments for investigating the effects of heat-and chemical treatments on corrosion resistance of the films.
The results of experiments were as follows:
(1) The corrosion resistance of anodic oxide films in acidic or basic solutions was lower than those of aluminum and its alloys. However, it was remarkably improved by treating the films with boiling water or boiling solutions of sodium acetate or sodium silicate-nickel acetate (tow-stepped treating).
(2) Salt spray tests revealed that the corrosion resistance was generally decreased by heat-treatment, but it was improved by two-stepped treating with boiling solutions of sodium silicate and nickel acetate.
(3) The corrosion resistance was remarkably decreased with the rise of temperature by heat-treatment during CASS test exposure. These results were obtained in the films having a large number of crazings produced by treating with boiling water or boiling solutions of sodium acetate or sodium silicate-nickel acetate (two-stepped treating).
