BLACK TRIVALENT CHROMIUM CHROMATE CONVERSION COATING

摘要

A composition and method for providing a blank chromate conversion coating is provided. The composition is substantially free of hexavalent chromium and provides a black finish, on zinc or zinc alloy coatings. The composition includes trivalent chromium ions, phosphorous anions, anions selected from the group consisting of sulfate ions, nitrate ions and combinations thereof, at least one of a transition metal or metalloid from Groups III, IVa, Va or VIII and an organic chelate selected from the group consisting of carboxylic acids, polycarboxylic acids and combinations thereof.