OXIDE COATED METAL PIGMENTS AND FILM-FORMING COMPOSITIONS

摘要

This invention relates to sacrificial-metal pigments coated with an effective amount of at least one metal oxide or a combination of metal oxides such as a mixture of chromium and zirconium oxides, and the process for preparing said coated pigments and combination thereof with film-forming binders for coating metal substrates to inhibit corrosion. The coated sacrificial-metal pigments are electrically active to prevent corrosion of metal substrates that are more cathodic (electropositive) than the metal oxide coated metal pigments.

主权项

1. A coated sacrificial-metal pigment having a particle size ranging from about 2 to 100 microns coated with an effective amount of at least one metal oxide selected from the group consisting of chromium oxide, zirconium oxide and mixtures of chromium and zirconium oxides; the uncoated metal pigment selected from the group consisting of zinc, magnesium, iron, aluminum, silver, copper and nickel; said metal oxide coating derived from an acidic aqueous composition consisting essentially of, in parts by weight, from 0.01 to 22 parts of a trivalent chromate, from 0.01 to 12 parts of hexafluorozirconate, from 0.01 to 12 parts of a fluorocarbon selected from the group consisting of tetrafluoroborate, hexafluorosilicate, and hexaflluorotitanates, from about 0.01 to 12 parts of a divalent zinc compound and from 0.01 to 5.0 parts of a water-soluble corrosion inhibitor.