High density thermal barrier coating

Abstract

A process for coating an article includes the steps of applying a bond coat layer onto at least one surface of an article; applying upon said bond coat layer a thermal barrier coating composition comprising a particle size distribution of no less than about 8 microns and no more than about 88 microns; heat treating said thermal barrier coating composition at a temperature of between about 1,800° F. to 2,200° F. for about 2 hours to 4 hours at a pressure of about 1×10−3 torr to 1×10−6 torr; and forming a thermal barrier coating layer comprising a cracking density of no more than about twenty cracks per linear inch of said thermal barrier coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a microphotograph of a thermal barrier coating of the prior art;

FIG. 2 is a microphotograph of a thermal barrier coating of the prior art;

FIG. 3 is a flowchart representing a process of the present invention;

FIG. 4 is a microphotograph of a 7EA First Bucket part no. GTD-111 produced by the General Electric Company coated with a non-heated treated yttria stabilized zirconia thermal barrier coating; and

FIG. 5 is a microphotograph of a 501F First Stage Blade produced by Siemens-Westinghouse coated with a heat-treated yttria stabilized zirconia thermal barrier coating.

Claims

1. A process for coating an article, comprising: applying a bond coat layer onto at least one surface of an article;applying upon said bond coat layer a thermal barrier coating composition comprising a particle size distribution of no less than about 8 microns and no more than about 88 microns;heat treating said thermal barrier coating composition at a temperature of between about 1,800° F. to 2,200° F. for about 2 hours to 4 hours at a pressure of about 1×10−3 torr to 1×10−6 torr; andforming a thermal barrier coating layer comprising a cracking density of no more than about twenty cracks per linear inch of said thermal barrier coating.

2. The process of claim 1, wherein the heat treating step comprises heat treating said thermal barrier coating composition under said vacuum at a temperature of about 2,175° F. for about 2 hours.

3. The process of claim 2, wherein the heat treatment step comprises heat treating said thermal barrier coating composition under said vacuum at a temperature of about 2,050° F. for about 2 hours.

4. The process of claim 1, wherein the heat treating step comprises heat treating said thermal barrier coating composition under said vacuum at a temperature of about 1,800° F. for about 4 hours.

5. The process of claim 1, wherein the heat treating step comprises heat treating said thermal barrier coating composition under said vacuum at a temperature of about 2,100° F. for about 4 hours.

6. The process of claim 1, wherein the application step of said bond coat layer comprises a process selected from the group consisting of plasma spray processes, low pressure plasma-spray processes, air plasma-spray processes, sputtering processes, cathodic arc processes, electron beam physical vapor deposition processes, high velocity plasma spray processes, combustion processes, wire spray processes, laser beam cladding processes and electron beam cladding processes.

7. The process of claim 1, wherein the application step of said thermal barrier coating composition comprises applying said thermal barrier coating composition using a plasma spray process.

8. The process of claim 7, wherein the application step of comprises using an arc gas comprising helium and argon present in a ratio of about 3:1 to 1:3.

9. The process of claim 7, wherein the application step comprises using an internal powder injection plasma spray gun.

10. The process of claim 9, further comprising operating said internal powder injection plasma spray gun at a current of between about 600 to 1000 amps.

11. The process of claim 9, further comprising operating said internal powder injection plasma spray gun at a distance of about 2 inches to 8 inches from said at least one surface of said article.

12. The process of claim 1, wherein the providing step of said thermal barrier coating composition comprises providing a powdered ceramic material selected from the group consisting of yttria stabilized zirconia, calcia stabilized zirconia, magnesia stabilized zirconia, yttria stabilized hafnia, calcia stabilized hafnia and magnesia stabilized hafnia.

13. The process of claim 1, wherein the providing step of said thermal barrier coating composition comprising providing a yttria stabilized zirconia powder.

14. The process of claim 1, wherein the application step of said bond coat layer comprises an application process selected from the group consisting of diffusion processes, low pressure plasma spray processes, air plasma spray processes, sputtering processes, cathodic arc processes, physical vapor deposition processes, high velocity plasma spray processes, combustion processes, wire spray processes, laser beam cladding processes and electron beam cladding processes.

15. A coated article, comprising: an article having at least one surface;a bond coat layer disposed upon said at least one surface; anda thermal barrier coating layer disposed upon said bond coat layer,wherein said thermal barrier coating layer comprises a heat treated thermal barrier coating composition having a particle size distribution of no less than about 8 microns and no more than about 88 microns,wherein said thermal barrier coating layer further comprises a cracking density of no more than about 20 cracks per linear inch of said thermal barrier coating.

16. The coated article of claim 15, wherein said thermal barrier coating layer comprises a porosity of no more than about 3 percent.

17. The coated article of claim 15, wherein said thermal barrier coating layer comprises a density of no less than about 98 percent.

18. The coated article of claim 15, wherein said thermal barrier coating layer includes a thermal barrier coating composition comprising a heat treated yttria stabilized zirconia powder.

19. The coated article of claim 15, wherein said article comprises a gas turbine engine component.

20. The coated article of claim 19, wherein said gas turbine engine component is selected from the group consisting of blades, vanes, stators, mid-turbine frame, fans, compressors, turbine casings, seals, plates, rings, combustor panels, combustor chambers, combustor bulkhead shields, disk side plates and fuel nozzle guides.

21. The coated article of claim 15, wherein said bond coat layer comprises a bond coat material comprising a formula MCrAlY, wherein said M is a metal selected from the group consisting of nickel, cobalt, iron and mixtures thereof.

22. The coated article of claim 15, wherein said bond coat layer comprises a bond coat material selected from the group consisting of aluminum, platinum and mixtures thereof.

23. The coated article of claim 15, wherein said bond coat layer comprises a bond coat material selected from the group consisting of aluminum, platinum and MCrAlY, wherein said M of said MCrAlY is a metal selected from the group consisting of nickel, cobalt, iron and mixtures thereof.

24. The coated article of claim 15, wherein said bond coat layer comprises a bond coat material comprising a formula MCrAlYHfSi, wherein said M of said MCrAlYHfSi is a metal selected from the group consisting of nickel, cobalt, iron and mixtures thereof.