亜鉛鋼板上へのコロイダルシリカ化成膜の成膜性に及ぼす浴組成の効果

概要

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Colloidal silica films were produced on zinc-electroplated steel using a new chemical conversion treatment, which provides an alternative to chromate conversion coating. The treatment solution consisted of colloidal silica, titanium sulfate, cobalt sulfate and nitrate ions at 298K, pH2. The corrosion resistance of the film coated specimens was estimated by impedance measurement in a sodium chloride solution for 8 days.The effects of colloidal silica concentration, treatment time and additive ions on corrosion resistance and adhesion of the film were investigated. The addition of titanium sulfate to the colloidal silica solution changed the surface potential of silica particles from negative to positive and improved the film characteristics. The addition of cobalt sulfate enhanced the adhesion between the zinc on the steel and the silica film. The film was not formed without nitride ions. Chemical conversion for 90s in a solution containing 200mM colloidal silica, 4.2mM titanium sulfate, 1.8mM cobalt sulfate, 4.2mM succinic acid and ajusted pH2 by nitric acid at 298K showed excellent film characteristics.
2003-11-01