Claims
- 1. A method for coating a metal part by dipspinning which comprises (a) contacting the metal surface to be coated with a thixotropic coating composition which comprises (1) an aqueous acid coating solution which solution comprises phosphate ions and ions of the group consisting of chromate ions or molybdate ions, and (2) a hydrated alumina having a boehmite type crystal lattice and being dispersible in the acid solution, (b) subjecting said part having said surface coating to a rapid spinning movement, whereby the composition flows onto the surface to be coated, (c) stopping the spinning and (d) curing the coating on said surface.
- 2. The method of claim 1 wherein said thixotropic coating composition includes fumed alumina.
- 3. The method of claim 2 wherein the fumed alumina is present in the amount of 0.25 to 10% by weight of composition.
- 4. The method of claim 1 wherein said thixotropic coating composition includes a nonionic surfactant.
- 5. The method of claim 4 wherein the amount of nonionic surfactant is in the range of about 0.01 to about 0.5% by weight of total solids.
- 6. The method of claim 1 wherein the pH range of the thixotropic coating composition is from about 0.5 to about 3.0.
- 7. The method of claim 1 wherein said thixotropic coating composition has a viscosity range from about 1,000 to about 50,000 cp.
- 8. The method of claim 7 wherein the viscosity range is from about 1,500 to about 10,000 cp.
- 9. A part coated with the cured composition which comprises (a) an aqueous acid coating solution which solution comprises phosphate ions and ions of the group consisting of chromate ions or molybdate ions, and (b) a hydrated alumina having a boehmite type crystal lattice and being dispersible in the acid solution.
- 10. The coated part of claim 9 wherein said coating composition contains fumed alumina.
- 11. The coated part of claim 10 wherein the fumed alumina is present in the amount of 0.25 to 10% by weight of said coating composition.
- 12. The coated part of claim 9 wherein said coating composition contains a nonionic surfactant and fumed silica.
- 13. The coated part of claim 12 wherein the amount of fumed silica in said coating composition is in the range of about 0.25 to 10% by weight of total solids.
- 14. The coated part of claim 9 wherein said coating composition includes a particulate solid material selected from the group consisting of aluminum, zinc, an oxide of the following: silicon, zirconium, beryllium or aluminum, iron, chromium, a refractory carbide, nitride, silicide, or boride, or alloy thereof.
- 15. The coated part of claim 14 wherein the particulate solid material is aluminum or an aluminum alloy.
- 16. The coated part of claim 15 wherein the particulate solid material is of an average particle size below about 10 microns.
- 17. The coated part of claim 9 wherein said coating composition comprises a gel of a reduced chromate.
- 18. The coated part of claim 17 wherein said gel is of a reduced water-soluble or water-insoluble chromate.
- 19. The coated part of claim 17 wherein said gel is an insoluble Cr(OH).sub.3 and/or a Cr.sub.2 (CrO.sub.4).sub.3 gel.
Parent Case Info
This application is a division of application Ser. No. 485,748, filed Apr. 18, 1983, now U.S. Pat. No. 4,544,408.
US Referenced Citations (2)
Number |
Name |
Date |
Kind |
3804663 |
Clark |
Apr 1974 |
|
4267212 |
Sakawaki |
May 1981 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
485748 |
Apr 1983 |
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