Process for reducing nickel leach rates for nickel acetate sealed anodic oxide coatings

Patent metadata

Field	Value
Publication number	US-10760176-B2
Application number	US-201514795832-A
Country	US
Kind code	B2
Filing date	Jul 9, 2015
Priority date	Jul 9, 2015
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

Sealed anodic coatings that are resistant to leaching of nickel and nickel-containing products and methods for forming the same are described. Methods involve post-sealing thermal processes to remove at least some of the leachable nickel from the sealed anodic coatings. In some embodiments, the post-sealing thermal processes involve immersing the sealed anodic coating within a heated solution so as to promote diffusion of the leachable nickel out of the sealed anodic coatings and into the heated solution. The resultant sealed anodic coating is pre-leached of nickel and is therefore well suited for many consumer product applications. In some embodiments, a post-sealing thermal process is used to further hydrate and seal the sealed anodic coating, thereby repairing structural defects within the sealed anodic coating.

First claim

What is claimed is:

1. A method of providing a sealed anodized coating, the method comprising:
heating the sealed anodized coating while immersed in a solution to a temperature that causes leachable material to diffuse from a sealant of the sealed anodized coating into the solution so that subsequent to the heating, the leachable material diffuses out of the sealant at no more than an in-service leach rate, the leachable material comprising at least one of nickel, oxalate, sulfate or a metal-based pigment.

2. The method of claim 1 , wherein the sealed anodized coating includes pores, and the sealant fills the pores.

3. The method of claim 1 , wherein, subsequent to immersing the sealed anodized coating in the solution, the pores are filled with the sealant.

4. The method of claim 1 , wherein, subsequent to immersing the sealed anodized coating in the solution, the pores of the sealed anodized coating remain filled with the sealant.

5. The method of claim 1 , wherein the sealed anodized coating has a microstructure, and the microstructure is maintained subsequent to immersing the sealed anodized coating in the solution.

6. The method of claim 1 , further comprising:
prior to immersing the sealed anodized coating in the solution, exposing the sealed anodized coating to a modification process that causes cracks within the sealed anodized coating, wherein immersing the sealed anodized coating in the solution is sufficient to minimize at least some of the cracks.

7. The method of claim 6 , wherein, prior to immersing the sealed anodized coating in the solution, the sealed anodized coating includes between 1 wt % to 3 wt % of the leachable material.

8. The method of claim 1 , wherein the leachable material is characterized as having a first diffusion rate, and the sealant is characterized as having a second diffusion rate different than the first diffusion rate.

9. A method of removing a leachable material from a sealed anodized coating, the leachable material comprising at least one of nickel, oxalate, a sulfate, or a metal-based pigment, the method comprising:
exposing the sealed anodized coating to a heated solution such as to cause diffusion of the leachable material from a sealant of the sealed anodized coating and into the heated solution at a target leach rate.

10. The method of claim 9 , wherein, prior to exposing the sealed anodized coating to the heated solution, pores of the sealed anodized coating are partially sealed with the sealant, and subsequent to exposing the sealed anodized coating to the heated solution, the pores are completely sealed with the sealant.

11. The method of claim 10 , further comprising:
prior to exposing the sealed anodized coating to the heated solution, forming the sealed anodized coating by exposing an anodized coating to a nickel acetate sealing solution.

12. The method of claim 11 , wherein the sealant includes nickel that is derived from the nickel acetate sealing solution.

13. The method of claim 10 wherein, subsequent to exposing the sealed anodized coating to the heated solution, a remaining amount of the leachable material included within the pores of the sealed anodized coating corresponds to an in-service leach rate.

14. A method of treating a sealed anodized coating, the sealed anodized coating having pores that are filled with a leachable material that comprises at least one of nickel, oxalate, sulfate or a metal-based pigment, the method comprising:
exposing the sealed anodized coating to a modification process such as to cause crazing of the sealed anodized coating; and
repairing the crazing of the sealed anodized coating by exposing the sealed anodized coating to a heated solution such as to cause an amount of the leachable material to diffuse from the sealed anodized coating into the heated solution at a target leach rate.

15. The method of claim 14 , wherein the modification process comprises at least one of a laser marking process or a surface finishing process.

16. The method of claim 14 , wherein a temperature of the heated solution is 80 degrees Celsius or higher.

17. The method of claim 14 , wherein the pores are filled with a sealant, and the leachable material is included in the sealant.

18. The method of claim 17 , wherein the leachable material and the sealant have different diffusion rates.

19. The method of claim 9 , wherein the sealed anodized coating includes between 1 wt % to 3 wt % of the leachable material.

20. The method of claim 14 , wherein, subsequent to repairing the crazing, a remaining amount of the leachable material included within the pores corresponds to an in-service leach rate.

Assignees

• Apple Inc

Inventors

• Curran James A
• Hamann Eric W
• Novak Sean R

Classifications

• C25D11/24 Primary

  Chemical after-treatment · CPC title

• C25D11/12 Primary

  Anodising more than once, e.g. in different baths · CPC title

• C25D11/243

  using organic dyestuffs · CPC title

• C25D11/246

  for sealing layers · CPC title