The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 03, 1995
Filed:
May. 06, 1993
Matthias P Schriever, Kent, WA (US);
The Boeing Company, Seattle, WA (US);
Abstract
(A.) A process for forming a cobalt conversion coating on a metal substrate, thereby imparting corrosion resistance and paint adhesion properties. The invention was developed as a replacement for the prior art chromic acid process. The process includes the steps of: (a) providing a cobalt conversion solution comprising an aqueous reaction solution containing a soluble cobalt-III hexacoordinated complex, the concentration of the cobalt-III hexacoordinated complex being from about 0.01 mole per liter of solution to the saturation limit of the cobalt-III hexacoordinated complex, and acetic acid; and (b) contacting the substrate with the aqueous reaction solution for a sufficient amount of time, whereby the cobalt conversion coating is formed. The substrate may be aluminum or aluminum alloy, as well as Cd plating, Zn plating, Zn--Ni plating, and steel. The cobalt-III hexacoordinated complex may be present in the form of [Co(NH.sub.3).sub.6 ]X.sub.3 wherein X is Cl, Br, NO.sub.3, CN, SCN, 1/3PO.sub.4, 1/2SO.sub.4, C.sub.2 H.sub.3 O.sub.2, or 1/3CO.sub.3. (B.) A chemical conversion coating solution for producing the cobalt conversion coating on a metal substrate, the solution, comprising an aqueous reaction solution containing a soluble cobalt-III hexacoordinated complex, the concentration of the cobalt-III hexacoordinated complex being from about 0.01 mole per liter of solution to the saturation limit of the cobalt-III hexacoordinated complex. The aqueous reaction solution may be prepared by a bath makeup sequence including the steps of: (a) dissolving a cobalt-II salt; (b) then dissolving a metal nitrate salt; and (c) then adding ammonium acetate. (C.) A coated article exhibiting corrosion resistance and paint adhesion properties, the article including: (a) a metal substrate; and (b) a cobalt conversion coating formed on the substrate, the cobalt conversion coating including aluminum oxide Al.sub.2 O.sub.3 as the largest volume percent, and cobalt oxides CoO, Co.sub.3 O.sub.4, and Co.sub.2 O.sub.3.