Corrosion resistant coating application method

Patent metadata

Field	Value
Publication number	US-9932665-B2
Application number	US-201514603233-A
Country	US
Kind code	B2
Filing date	Jan 22, 2015
Priority date	Jan 22, 2015
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A process for applying a chromized layer on a substrate by first applying an overlay coating to a portion of the substrate, and subsequently contacting a different portion of the substrate and the overlay with a gas containing gaseous chromium, wherein the gaseous chromium can be generated from a chromium source and an activator. The process prepares the substrate, often a jet engine airfoil, for service.

First claim

The invention claimed is:

1. A process for applying a chromized layer on a substrate comprising the steps of: applying an overlay coating to a portion of the substrate, and contacting a different portion of the substrate and the overlay with a gas containing gaseous chromium wherein the gaseous chromium is generated from a chromium source and an activator so as to deposit the chromized layer on the different portion of the substrate, wherein the overlay is a ceramic thermal barrier coating.

2. A process according to claim 1 , wherein the ceramic thermal barrier coating contains ceramics selected from the group consisting of Lanthanum Zirconate and Gadolinium Zirconate, Yttria-stabilized zirconia and mixtures thereof.

3. A process according to claim 1 , wherein the thermal barrier coating is applied using a method selected from the group consisting of: electron beam physical deposition, air plasma spray and combinations thereof.

4. A process according to claim 1 , wherein the applying step comprises applying a metallic overlay to the portion of the substrate and applying the ceramic thermal barrier coating to the metallic overlay.

5. A process according to claim 1 , wherein the substrate is an aircraft engine airfoil.

6. A process according to claim 5 , wherein the airfoil is a high pressure stage turbine airfoil.

7. A process according to claim 1 , wherein the substrate is made of a nickel-based superalloy.

8. A process according to claim 1 , wherein the gaseous chromium comprises chromium halide compounds.

9. A process according to claim 1 , wherein the process takes place in an enclosed space.

10. A process according to claim 1 , wherein the applying step takes place in a vacuum.

11. A process according to claim 10 , wherein temperature inside the enclosed space is between 1000° F. and 1975° F. during the applying step.

12. A process according to claim 10 , wherein temperature inside the enclosed space is between 1950° F. and 2000° F. during the contacting step.

13. A process according to claim 12 , wherein temperature inside the enclosed space is held between 12 and 16 hours during the contacting step.

14. A process according to claim 1 , wherein the contacting step does not negatively affect bond coat oxidation, hot corrosion resistance, thermal bond coating spallation life, mechanical properties and thermal conductivity of the overlay.

15. A process according to claim 1 , wherein the chromized layer contains chromium in an amount between 17% and 40% by weight.

16. A process according to claim 1 , wherein the ratio of chromium to activator is 0.3:1.

17. A process according to claim 1 , wherein the chromium is present in an amount between 25 and 60% by weight of combined chromium source and activator.

18. A process according to claim 1 , wherein thickness of alpha (α) chromium at the surface of the chromized layer does not exceed 0.0002 inches.

19. A process according to claim 1 , wherein the resulting thickness of the chromized layer produced by the contacting step is between 0.0006 and 0.0013 inches on the substrate.

20. A process according to claim 1 , wherein the substrate contains internal air passageways and wherein the contacting step deposits the chromized layer on the internal passageways.

21. A process according to claim 20 , wherein the chromized layer contains at least 17% by weight chromium on the internal air passageways.

22. A process according to claim 21 , wherein thickness of the chromized layer produced by the contacting step is between 0.0003 and 0.0013 inches on the internal passageways.

23. A process according to claim 1 , wherein the substrate is put into service after the contacting step.

Assignees

• United Technologies Corp

Inventors

• Beers Russell A
• Task Michael N

Classifications

• C23C10/10

  Chromising · CPC title

• C23C14/14

  Metallic material, boron or silicon · CPC title

• C23C14/221 Primary

  Ion beam deposition (C23C14/46, C23C14/48 take precedence) · CPC title

• C23C10/04 Primary

  Diffusion into selected surface areas, e.g. using masks · CPC title

• Y02T50/60

  Efficient propulsion technologies, e.g. for aircraft · CPC title