Two-step sealing of anodized aluminum coatings

Patent metadata

Field	Value
Publication number	US-10760164-B2
Application number	US-201816226042-A
Country	US
Kind code	B2
Filing date	Dec 19, 2018
Priority date	Nov 4, 2016
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

A method includes providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant. The at least one surface of the workpiece is submerged in a post-treatment sealant solution for 0.5 to 20 minutes. The sealant composition consists essentially of a corrosion inhibitor formulation, a water soluble polymer, an organic complexing agent, and an oxidant. The corrosion inhibitor formulation is formulated from at least one anodic corrosion inhibitor compound, at least one cathodic corrosion inhibitor compound, or a combination thereof. A concentration of each of the corrosion inhibitor formulation, the water soluble polymer, the organic complexing agent, and the oxidant is each in a range of 1-50 mM.

First claim

The invention claimed is:

1. A sealant composition consisting essentially of:
a corrosion inhibitor formulation;
a water soluble polymer;
an organic complexing agent;
an oxidant; and
water;
wherein the corrosion inhibitor formulation is formulated from at least one anodic corrosion inhibitor compound, at least one cathodic corrosion inhibitor compound, or a combination thereof;
and wherein a concentration of each of the at least one anodic corrosion inhibitor compound, the at least one cathodic corrosion inhibitor compound, or the combination thereof, the corrosion inhibitor formulation, the water soluble polymer, the organic complexing agent, and the oxidant is each in a range of 1-50 mM based on the sealant composition.

2. The composition of claim 1 , wherein the at least one anodic corrosion inhibitor compound is selected from a group consisting of: a molybdate compound, a silicate compound, a phosphate compound, an orthophosphate compound, and combinations thereof.

3. The composition of claim 2 , wherein the molybdate compound or the silicate compound comprise zinc cations, calcium cations, magnesium cations, or combinations thereof.

4. The composition of claim 2 , wherein the phosphate compound or the orthophosphate compound comprise zinc cations, calcium cations, strontium cations, aluminum cations, or combinations thereof.

5. The composition of claim 1 , wherein the at least one cathodic corrosion inhibitor compound comprises a rare earth salt of an organic carboxylic acid.

6. The composition of claim 5 , wherein the rare earth salt comprises cerium ions, lanthanum ions, citrate ions and combinations thereof.

7. The composition of claim 2 , wherein the corrosion inhibitor formulation consists essentially of zinc molybdate, cerium (III) citrate, and magnesium silicate.

8. The composition of claim 1 , wherein the water soluble polymer is selected from a group consisting of: a poly-amine compound, a polyol compound, a poly-thiol compound, and combinations thereof.

9. The composition of claim 8 , wherein the organic complexing agent is selected from a group consisting of: a phytate, an EDTA, a thiourea, a benzotriazole, nitrilotriacetic acid, citric acid, a polycarboxylic acid, and combinations thereof.

10. The composition of claim 9 , wherein the oxidant is selected from a group consisting of: a permanganate, a peroxide, a persulfate, a percarbonate, a perborate, and combinations thereof.

11. The composition of claim 10 , wherein a pH of the sealant composition is between 3 and 9.

12. The composition of claim 11 , wherein the pH of the sealant composition is between 4 and 6.

13. A method comprising:
providing a workpiece with at least one surface having an anodized aluminum coating and a trivalent chromium sealant;
submerging the at least one surface of the workpiece in a post-treatment sealing solution for 0.5 to 20 minutes, the sealing solution comprising: a corrosion inhibitor formulation;
a water soluble polymer;
an organic complexing agent;
an oxidant; and
water;
wherein the corrosion inhibitor formulation is formulated from at least one anodic corrosion inhibitor compound, at least one cathodic corrosion inhibitor compound, or a combination thereof;
and wherein a concentration of each of the at least one anodic corrosion inhibitor compound, the at least one cathodic corrosion inhibitor compound, or the combination thereof, the corrosion inhibitor formulation, the water soluble polymer, the organic complexing agent, and the oxidant is each in a range of 1-50 mM based on the sealant composition.

14. The method of claim 13 , wherein the at least one anodic corrosion inhibitor compound is selected from a group consisting of: a molybdate compound, a silicate compound, a phosphate compound, an orthophosphate compound, and combinations thereof, and the at least one cathodic corrosion inhibitor compound comprises a rare earth salt of an organic carboxylic acid.

15. The method of claim 14 , wherein the molybdate compound or the silicate compound comprise zinc cations, calcium cations, magnesium cations, or combinations thereof, and the phosphate compound or the orthophosphate compound comprise zinc cations, calcium cations, strontium cations, aluminum cations, or combinations thereof.

16. The method of claim 14 , wherein the rare earth salt comprises cerium ions, lanthanum ions, citrate ions, or combinations thereof.

17. The method of claim 14 , wherein the corrosion inhibitor formulation consists essentially of zinc molybdate, cerium (III) citrate, and magnesium silicate.

18. The method of claim 14 , wherein the water soluble polymer is selected from a group consisting of: a poly-amine compound, a polyol compound, a poly-thiol compound, and combinations thereof, and the organic complexing agent is selected from a group consisting of: a phytate, an EDTA, a thiourea, a benzotriazole, a nitrilotriacetic acid, a citric acid, a polycarboxylic acid, and combinations thereof.

19. The method of claim 18 , wherein the oxidant is selected from a group consisting of: a permanganate, a peroxide, a persulfate, a percarbonate, a perborate, and combinations thereof.

20. The method of claim 19 , further comprising:
maintaining a solution pH in a range between 3 and 9; and
maintaining a process temperature in a range of 20° C. to 80° C.

Assignees

• Hamilton Sundstrand Corp

Inventors

• Ding Zhongfen
• Zhang Weilong
• Smith Blair A
• Jaworowski Mark R
• Zafiris Georgios S

Classifications

• C25D11/246 Primary

  for sealing layers · CPC title

• C23C2222/10

  Use of solutions containing trivalent chromium but free of hexavalent chromium · CPC title

• C23C22/83

  Chemical after-treatment · CPC title

• C23F13/005

  Anodic protection · CPC title

• C23C22/42

  containing also phosphates · CPC title