NICKEL-ZINC PHOSPHATE CONVERSION COATINGS

摘要

A method of applying a phosphate conversion coating to a metal surface, including the steps of: (a) providing an aqueous, acidic treatment solution comprising: phosphate ions; zinc cations; and nickel (II) cations; wherein the treatment solution has between about 2.1 and about 6.0 points of free acid; and (b) contacting the metal surface with the treatment solution for a time and at a temperature sufficient to form a phosphate conversion coating on the metal surface. A metal object coated in this manner is also provided, and the gram-atom percent of nickel to the total amount of nickel and zinc in the coating is between about 10 and about 13.