Oxide coated metal pigments and film-forming compositions

• US 10,174,206 B2
• Filed: 11/24/2015
• Issued: 01/08/2019
• Est. Priority Date: 01/21/2011
• Status: Active Grant

• Current Assignee: US Department of The Navy (U.S. Department Of Defense)
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Matzdorf, Craig, Nickerson, William
• Primary Examiner(s): Nguyen, Haidung D
• Application Number:
  US14/950,835
• Publication Number:
  US 20160108252A1
• Time in Patent Office: 1,141 Days
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C09C 1/62 Metallic pigments or fillers C09C1/0015 takes precedence
• CPC Class Codes: C09C 1/642 treated with inorganic compounds
• CPC Class Codes: C09D 5/00 Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced electrically insulating plastics, resins or waxes H01B3/30; Filling pastes
• CPC Class Codes: C09D 5/08 Anti-corrosive paints
• CPC Class Codes: C09D 5/082 characterised by the anti-corrosive pigment
• CPC Class Codes: C09D 5/10 containing metal dust
• CPC Class Codes: C09D 7/48 Stabilisers against degradation by oxygen, light or heat
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: C09D 7/62 modified by treatment with other compounds
• CPC Class Codes: C09D 7/70 characterised by shape, e.g. fibres, flakes or microspheres
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C23C 22/34 containing fluorides or complex fluorides
• CPC Class Codes: C23C 2222/10 Use of solutions containing trivalent chromium but free of hexavalent chromium
• CPC Class Codes: C23F 11/00 Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent adding inhibitors to mineral oil, fuels, or lubricants C10; adding inhibitors to pickling solutions C23G
• CPC Class Codes: C23F 11/08 in other liquids
• CPC Class Codes: C23F 11/10 using organic inhibitors
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft

Abstract

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.

Claims

1. A coated sacrificial-metal pigment having a particle size ranging from about 2 to 100 microns said pigment is 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 hexafluorotitanates, 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.

2. The coated sacrificial-metal pigment of claim 1 wherein the coated metal pigment is aluminum coated with mixtures of chromium and zirconium oxides.

3. The coated sacrificial-metal pigment of claim 2, wherein the divalent zinc compound is zinc sulfate.

4. The coated sacrificial-metal pigment of claim 1, wherein the water soluble corrosion inhibitor is selected from the group consisting of a benzimidazole, a benzothiazole, a benzoxazole, a diphenyltriazole, a benzotriazole and a tolytriazole.

5. The coated sacrificial-metal pigment of claim 1, wherein the uncoated metal pigment is aluminum.

6. The coated sacrificial metal pigment of claim 1, wherein the uncoated metal pigment is nickel.

7. The coated sacrificial-metal pigment of claim 1, wherein the uncoated metal pigment is magnesium.

8. The coated sacrificial-metal pigment of claim 4, wherein the water soluble corrosion inhibitor is benzotriazole.

9. The coated sacrificial-metal pigment of claim 1, wherein the aqueous composition has a pH of from about 2.5 to 5.5.

26. A process for preparing the coated sacrificial-metal pigment of claim 1 which comprises coating said metal pigment 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, said 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 hexafluorotitanates, 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.

27. The process of preparing the coated sacrificial-metal pigment of claim 26 wherein the coated metal pigment is aluminum coated with a mixture of chromium and zirconium oxides.

10. An electrochemically corrosion-resistant composition for application onto metal substrates consisting essentially of, in parts by weight, from about

5 to 80 parts of a film-forming binder selected from the group consisting of an inorganic binder, polyurethanes, polyimides, polyacrylates, polymers derived from diisocyanates, polymers derived from epoxies and the uncured prepolymers of said polymers, from about

0.0 to 10 parts of at least one organic corrosion-inhibitor, from about

0.0 to 5.0 parts of at least one surfactant, from about

0.0 to 5.0 parts of solvent, and from about

to 80 parts of a coated sacrificial-metal pigment having a particle size ranging from about 2 to 100 microns;

said sacrificial-metal pigment coated with effective amounts of at least one metal oxide derived from a composition consisting essentially of an acidic aqueous solution comprising from about 0.01 to 22 parts of a trivalent chromium compound, from about 0.01 to 12 parts of hexafluorozirconate, from about 0.01 to 12 parts of at least one fluorocarbon selected from the group consisting of tetrafluoroborates, hexafluorosilicates, and hexafluorotitanates, from about 0.01 to 12 parts of at least one divalent zinc compound, and from about 0.0 to 5 parts by weight of a water-soluble corrosion inhibitor.

11. The corrosion-resistant composition of claim 10, wherein at least one of the divalent zinc compounds is zinc sulfate.

12. The corrosion-resistant composition of claim 10, wherein the pH of the acidic aqueous solution ranges from about 2.5 to 5.5.

13. The corrosion-resistant composition of claim 10, wherein an effective amount of the oxide is coated onto the metal pigment in an amount ranging up to ten mils of coating thickness.

14. The corrosion-resistant composition of claim 10, wherein the sacrificial metal pigment has a particle size ranging from about 20-46 microns.

15. The corrosion-resistant composition of claim 10, wherein the coated sacrificial metal pigment ranges from about 50 to 70 parts of the composition.

16. The corrosion-resistant composition of claim 10, wherein the film-forming inorganic binder is polysiloxane.

17. The corrosion-resistant composition of claim 10, wherein the solvent ranging from 1.0 to 5.0 parts.

18. An electrochemically corrosion-resistant composition for application onto metal substrates consisting essentially of, in parts by weight, from about

5 to 80 parts of an oleaginous composition consisting of an organic lubricant, from about

0.1 to 10 parts of at least one organic corrosion inhibitor, from about

0.1 to 5.0 parts of at least one surfactant, from about

1.0 to 5.0 parts of organic solvent, and from about

to 80 parts by weight of a coated sacrificial-metal pigment having a particle size ranging from about 2 to 100 microns;

said metal pigment 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 derived from an acidic aqueous solution having a pH of about 2.5-5.5 consisting of from about 0.01 to 22 parts of a trivalent chromium compound, from about 0.01 to 12 parts of hexafluorozirconate, from about 0.01 to 12 parts of at least one fluorocarbon selected from the group consisting of tetrafluoroborates, hexafluorosilicates, and hexafluorotitanates, from about 0.01 to 12 parts of at least one divalent zinc compound, and from about 0.01 to 5 parts by weight of a water soluble corrosion inhibitor.

19. The corrosion-resistant composition of claim 18, wherein the divalent zinc compounds is zinc sulfate.

20. The corrosion-resistant composition of claim 18, wherein the lubricant is a grease composition.

21. The corrosion-resistant composition of claim 18, wherein the metal pigment is coated with a mixture of chromium and zirconium oxides.

22. The composition of claim 18, wherein the metal pigment is coated with chromium oxide.

23. The composition of claim 18, wherein the metal pigment is coated with zirconium oxide.

24. The composition of claim 18 wherein the water soluble corrosion inhibitor is an azole.

25. The composition of claim 24 wherein the azole is benzotriazole.