Non-chromate conversion films are formed on the of chloride ions and the pH value of the chloride surface of an Al-Zn-Mg-Cu alloy using a two step cerium salt treatment. The corrosion resistance of the alloy in chloride solution has been studied after the non-chromate treatment. It was found that the conversion film could greatly improve the corrosion resistance of the alloy to pitting and uniform corrosion in a chloride environment. The non-chromate film can retard both the anodic and cathodic processes. The treated alloy is not sensitive to the changes in the concentration of chloride ions and the pH value of the chloride solution.
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