| 摘要 |
An aqueous liquid chromate free composition for forming a protective coating on metals, particularly aluminum, is made by reacting cobalt (II) cations, carboxylate anions, at least one other type of coordinate complexing agent for cobalt (III) cations, and an oxidizing agent in an aqueous solution in which the molar ratio of carboxylate anions to cobalt (II) cations is from 0.10 to 6.8 and the aqueous solution contains no more than 1 % of each of ammonia, ammonium ions, and nitrite ions.
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