Constant voltage anodizing of Al in Kalcolor electrolyte generates integral colored films at high voltage. However, this method requires a large rectifire because of excessive flow of electric current in the beginning of coloring, and also it means an expensive method additionally.
Therefore a new method was studied. Constant color films were obtained by the constant voltage anodizing following after the constant current anodizing.
Experimental results indicated that the most suitable composition of the electrolyte was 2.5-5% sulfosalicylic acid and 0.2% sulfuric acid. And the best anodizing conditions were current density: 2-3 A/dm² in the constant current period, and voltage: ≥60 V, time: ≥10min. in the constant voltage period. Anodized films were colored darker as the coloring voltage increased. The color of films was not affected by bath temperature and agitation.

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