| 摘要 |
A method is described for producing an iridescent chromium coating on a zinc-nickel alloy surface containing at least about 8% nickel in the alloy. The method of the invention comprises (A) contacting said surface with an aqueous acidic solution maintained at a temperature of from about 38 DEG C. to about 75 DEG C., wherein the solution comprises trivalent chromium as substantially the only chromium ion present, and a phosphorus acid selected from phosphoric acid, phosphorous acid, hypophosphorous acid and mixtures thereof in an amount effective to provide a solution having a pH of from about 1.0 to about 2.5; and (B) drying the surface. Metal articles having zinc-nickel alloy surfaces containing at least about 8% nickel in the alloy which have been treated in accordance with the method of the invention exhibit the desired iridescent coating and are characterized by improved corrosion resistance.
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