Coating solutions of trivalent chromium for coating zinc surfaces
AssigneeR. O. Hull & Company, Inc.
InventorsCraig V. Bishop, Thomas J. Foley, James M. Frank
Life of this patent
Estimating the term…
Abstract
Aqueous acidic coating solutions are described for treating zinc or zinc alloy surfaces comprising trivalent chromium as substantially the only chromium ion present, fluoride ion, an acid other than nitric acid, and an oxidizing agent. The coating solutions containing trivalent chromium as substantially the only chromium ion present preferably are prepared by reducing an aqueous solution of hexavalent chromium with sufficient reducing agent to reduce all of the hexavalent chromium to trivalent chromium. Chromate coatings on zinc and zinc alloy surfaces are produced by contacting said surfaces with an aqueous acidic solution of the invention.
Claims18
An aqueous acidic coating solution for treating a zinc or zinc alloy surface consisting essentially of trivalent chromium as substantially the only chromium ion present, fluoride ion, an acid other than nitric acid, and an inorganic halate or peroxide.
An aqueous acidic coating solution for treating a zinc or zinc alloy surface comprising trivalent chromium as substantially the only chromium ion present, fluoride ion, sulfuric acid and hydrogen peroxide.
An aqueous acidic coating solution for treating zinc or zinc alloy surfaces comprising from about 0.2 to about 1.0 grams per liter of trivalent chromium ion as substantially the only chromium ion present, from about 0.2 to about 1.0 grams per liter of fluoride ion, from about 3 to about 50 grams per liter of a peroxide, 0 to about 0.1 grams per liter of a cationic wetting agent and a sufficient amount of sulfuric, hydrochloric, acetic, sulfamic or phosphoric acid to regulate the pH of the solution between about 1 to about 4.
Dependencies are inferred from the claim text.