Aluminum slurry coatings and methods of their formation and use

Patent metadata

Field	Value
Publication number	US-12409495-B2
Application number	US-202318507267-A
Country	US
Kind code	B2
Filing date	Nov 13, 2023
Priority date	Aug 24, 2021
Publication date	Sep 9, 2025
Grant date	Sep 9, 2025

Abstract

Methods for reducing a concentration of hexavalent chromium within a first aluminum slurry by adding a reducing agent to form a second aluminum slurry are provided. The reducing agent causes a chemical reduction reaction with the hexavalent chromium compound of the first aluminum slurry to form a trivalent chromium compound within the second aluminum slurry such that a first weight ratio of hexavalent chromium to trivalent chromium in the first aluminum slurry is decreased to a second weight ratio of hexavalent chromium to trivalent chromium in the second aluminum slurry, with the second weight ratio being less than the first weight ratio.

First claim

What is claimed is:

1. A slurry, comprising:
an aluminum powder;
an acidic phosphate;
a chromium oxide, wherein the chromium oxide comprises hexavalent chromium and trivalent chromium at a weight ratio of hexavalent chromium to trivalent chromium of 0.001 to 3; and
water.

2. The slurry of claim 1 , wherein the weight ratio of hexavalent chromium to trivalent chromium is 0.001 to 2.

3. The slurry of claim 1 , further comprising:
a reducing agent.

4. The slurry of claim 3 , wherein the reducing agent comprises a second aluminum powder, an iron powder, a zinc powder, or a mixture thereof.

5. The slurry of claim 3 , wherein the reducing agent comprises a powder of a substantially pure metal of aluminum, iron, or zinc.

6. The slurry of claim 1 , wherein the hexavalent chromium comprises less than 0.1% of the slurry.

7. The slurry of claim 1 , wherein the trivalent chromium comprises 0.5% by weight to 3% of the slurry.

8. The slurry of claim 1 , further comprising a second aluminum powder.

9. The slurry of claim 8 , wherein the second aluminum powder comprises an unoxidized aluminum powder.

10. The slurry of claim 8 , wherein the second aluminum powder comprises an oxidized aluminum powder.

11. The slurry of claim 1 , wherein the hexavalent chromium is less than 0.1% by weight of the slurry and the trivalent chromium is 0.5% by weight to 3% by weight of the slurry.

12. A method of repairing a damaged coating, the method comprising:
removing a damaged coating from a surface of the substrate; and
thereafter, applying the slurry of claim 1 onto the surface of the substrate.

13. A slurry, comprising:
a first aluminum powder;
a second aluminum powder;
an acidic phosphate;
less than 0.1% by weight hexavalent chromium;
0.5% by weight to 3% by weight trivalent chromium,
wherein the weight ratio of hexavalent chromium to trivalent chromium is 0.001 to 3; and
water.

14. The slurry of claim 13 , wherein the hexavalent chromium comprises less than 0.01% by weight of the slurry.

15. The slurry of claim 13 , wherein the second aluminum powder comprises an unoxidized aluminum powder.

16. The slurry of claim 13 , wherein the second aluminum powder comprises an oxidized aluminum powder.

17. The slurry of claim 13 , consisting essentially of:
a first aluminum powder;
a second aluminum powder;
an acidic phosphate;
less than 0.1% by weight hexavalent chromium;
0.5% by weight to 3% by weight trivalent chromium; and
water.

18. The slurry of claim 13 , consisting essentially of:
a first aluminum powder;
a second aluminum powder;
an acidic phosphate;
less than 0.01% by weight hexavalent chromium;
0.5% by weight to 3% by weight trivalent chromium; and
water.

Assignees

• Gen Electric

Inventors

• Kool Lawrence Bernard
• Rhoads Mark Alan

Classifications

• B22F2302/25

  Oxide · CPC title

• B22F2301/052

  Aluminium · CPC title

• B22F1/147

  Making a dispersion · CPC title

• B22F1/145

  Chemical treatment, e.g. passivation or decarburisation · CPC title

• C23C22/73

  characterised by the process · CPC title