PPG patents conversion coating with alkaline earth metal fluoride complexes

May 9, 2011

U.S. 7,776,448 B2

PPG Industries Ohio, Inc. has received a patent for a coated metal substrate comprised of a metal surface which has been contacted with an aqueous crystalline-forming composition comprised of a Group IIA dissolved metal ion; a dissolved complex metal fluoride ion wherein the metal atom is selected from Group IIIA, Group IVA, Group IVB, Group VA, and Group VB metals; a complex forming metal salt different from the complex metal fluoride ion, and water, wherein the complex forming metal salt complexes free fluoride ions to provide an aqueous composition which is substantially free of Group IIA metal fluoride precipitate; and wherein the complex forming metal salt is selected from the group consisting of sodium metasilicate, polysilicate, Zeolites, zirconyl nitrate, titanyl sulfate, tetrafluorozirconate, tetrafluorotitanate.