Method for selective aluminide diffusion coating removal

Patent metadata

Field	Value
Publication number	US-10590800-B2
Application number	US-201415310805-A
Country	US
Kind code	B2
Filing date	Sep 25, 2014
Priority date	Sep 25, 2014
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A method for selective aluminide diffusion coating removal. The method includes diffusing aluminum into a substrate surface of a component to form a diffusion coating. The diffusion coating includes an aluminum-infused additive layer and an interdiffusion zone. The diffusion coating is solution heat treated at a temperature and for a time sufficient to dissolve at least a portion of the interdiffusion zone. Thereafter the aluminum-infused additive layer is selectively removed. An aluminide diffusion coated turbine component is also disclosed.

First claim

The invention claimed is:

1. A method for selective aluminide diffusion coating removal, the method comprising:
diffusing aluminum into a substrate surface of a component to form a diffusion coating, the diffusion coating comprising an aluminum-infused additive layer and an interdiffusion zone;
solution heat treating the diffusion coating under vacuum at a temperature and for a time sufficient to dissolve at least a portion of the interdiffusion zone; and thereafter
selectively removing the aluminum-infused additive layer.

2. The method of claim 1 , wherein the component is a component selected from the group consisting of a shroud, a turbine blade, a nozzle and a vane.

3. The method of claim 1 , wherein the solution heat treatment includes heating the diffusion coating to a temperature of from 2000° F. to 2300° F.

4. The method of claim 3 , wherein the solution heat treatment includes heating the diffusion coating for a time between about 1 to 4 hours.

5. The method of claim 1 , wherein the selectively removing includes removing by one of the group selected from grit blasting, water jet abrasive stripping, laser ablation and acid dipping.

6. The method of claim 1 , wherein the selectively removing includes grit blasting.

7. The method of claim 1 , wherein the selectively removing includes acid dipping.

8. The method of claim 1 , wherein the selectively removing includes a reduction in the thickness of the component of less than 0.3 mils.

9. The method of claim 1 , wherein the selectively removing includes a reduction in the thickness of the component of less than 0.2 mils.

10. The method of claim 1 , wherein the selectively removing includes a reduction in the thickness of the component of less than 0.1 mils.

11. A method for aluminide diffusion coating removal from a substrate of a gas turbine component, the method comprising:
removing the component from a gas turbine after operation of the gas turbine, the component having a diffusion coating, the diffusion coating comprising an aluminum-infused additive layer and an interdiffusion zone;
solution heat treating the diffusion coating under vacuum at a temperature and for a time sufficient to dissolve at least a portion of the interdiffusion zone; and thereafter
selectively removing the aluminum-infused additive layer.

12. The method of claim 11 , wherein the component is a component selected from the group consisting of a shroud, a turbine blade, a nozzle and a vane.

13. The method of claim 11 , wherein the solution heat treatment includes heating the diffusion coating to a temperature of from 2000° F. to 2300° F.

14. The method of claim 13 , wherein the solution heat treatment includes heating the diffusion coating for a time between about 1 to 4 hours.

15. The method of claim 11 , wherein the selectively removing includes removing by one of the group selected from grit blasting, water jet abrasive stripping, laser ablation and acid dipping.

16. The method of claim 11 , wherein the selectively removing includes grit blasting.

17. The method of claim 11 , wherein the selectively removing includes acid dipping.

18. The method of claim 11 , wherein the selectively removing includes a reduction in the thickness of the component of less than 0.3 mils.

19. An aluminide diffusion coated turbine component comprising:
a substrate comprising a nickel-based or cobalt-based superalloy; and
an aluminide diffusion coating on a surface of the substrate, the aluminide diffusion coating having a dissolved interdiffusion zone, the dissolved interdiffusion zone being a zone in which at least a portion of a preexisting interdiffusion zone is dissolved into the substrate under vacuum,
wherein an aluminum-infused additive layer has been selectively removed from the aluminum diffusion coating, and,
wherein the dissolved interdiffusion zone is resistant to removal relative to an aluminum-infused additive layer of a comparative aluminide diffusion coating which is identical to the aluminide diffusion coating except that the preexisting interdiffusion zone is not dissolved into a comparative substrate and an aluminum-infused additive layer has not been selectively removed.

20. The aluminide diffusion coated turbine component of claim 19 , wherein the component is a component selected from the group consisting of a shroud, a turbine blade, a nozzle and a vane.

Assignees

• Gen Electric
• Zhang Liming
• Johnson Jere A
• Zhou Ying

Inventors

• Zhang Liming
• Johnson Jere A
• Zhou Ying

Classifications

• F01D25/005

  Selecting particular materials · CPC title

• C23C10/28 Primary

  using solids, e.g. powders, pastes · CPC title

• C23F1/20

  for etching aluminium or alloys thereof · CPC title

• F05D2230/90

  Coating; Surface treatment · CPC title

• B24C1/086

  Descaling; Removing coating films · CPC title