Influence of Additions of Water on the Quality of Filled Anodic Oxide Coatings

Author： Yavors'kyi V. T. Mertsalo I. P. Klapkiv M. D. Savchuk L. V. Olynets' V. T.

ISSN： 1068-820X

Source： Materials Science, Vol.39, Iss.5, 2003-09, pp. : 745-749

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Abstract

We investigate the influence of anion-cation composition of an aqueous medium on the etching rate in an acid electrolyte and the resistance of the insulation of a filled oxide coating. We reveal the cations and anions of the aqueous medium that increase the etching rate of the coating and decrease its insulation resistance. We establish that Al³⁺ and Mg²⁺ cations and ${\rm SiO}_3^{2-}$ anions have a considerable effect on the quality of the filled coating. A high-quality coating is obtained if their concentrations in the aqueous medium are at most (mg/liter) 100 for Al³⁺, 700 for Mg²⁺, 800 for Cl⁻, and 13 for ${\rm SiO}_3^{2-}$ . The optimum pH of the environment is equal to 6 and the time of treatment of a coating in distilled water is equal to 60 ± 5 min.