ALUMINA-BASED PROTECTIVE COATINGS FOR THERMAL BARRIER COATINGS

• US 20090110903A1
• Filed: 10/24/2007
• Published: 04/30/2009
• Est. Priority Date: 10/24/2007
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Margolies, Joshua L.
• Granted Patent: US 7,833,586 B2
• Time in Patent Office: Days
• US Class Current: 428/304.400
• CPC Class Codes: C23C 28/04 only coatings of inorganic non-metallic material
• CPC Class Codes: C23C 28/042 including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides
• CPC Class Codes: C23C 28/3215 at least one MCrAlX layer
• CPC Class Codes: C23C 28/345 with at least one oxide layer
• CPC Class Codes: C23C 28/3455 with a refractory ceramic layer, e.g. refractory metal oxide, ZrO2, rare earth oxides or a thermal barrier system comprising at least one refractory oxide layer
• CPC Class Codes: C23C 4/02 Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• CPC Class Codes: C23C 4/10 Oxides, borides, carbides, nitrides or silicides; Mixtures thereof
• CPC Class Codes: C23C 4/11 Oxides
• CPC Class Codes: C23C 4/18 After-treatment
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/31678 Of metal

Abstract

A thermally sprayed alumina-based coating is deposited onto a thermal barrier coating to provide an article such as a turbine engine component with both CMAS mitigation and antifouling. The alumina-based coating increases a melting point of the CMAS to a temperature greater than an operating temperature of the turbine engine component. The surface roughness of the thermally sprayed alumina based coating in less than 4.0 micrometers to 0.75 micrometers. The alumina based coatings include at least 60 weight percent alumina based on a total weight of the alumina-based coating.

Claims

1. A process for depositing an alumina-based coating onto a thermal barrier coating, the process comprising

providing an article with a thermal barrier coating disposed thereon;

heating an alumina powder, wherein the alumina powder has a composition of at least 60 weight percent alumina with a balance comprising titania, zirconia, and gadolinia based on a total weight of the alumina-based coating; and

thermally spraying the alumina powder onto the thermal barrier coating to form the alumina-based coating, wherein the alumina-based coating increases a melting point of a contaminant composition comprising mixed calcium-magnesium-aluminum-silicon-oxides relative to the contaminant composition in the absence of the alumina-based coating.

2. The process of claim 1, wherein the alumina-based coating has an average surface roughness of less than 4.0 micrometers to 0.75 micrometers.

3. The process of claim 1, wherein thermally spraying the alumina powder comprises a high velocity oxygen fuel flame process.

4. The process of claim 1, wherein thermally spraying the alumina powder comprises high velocity air plasma spray process.

5. The process of claim 1, wherein the thermal barrier coating comprises a chemically stabilized zirconia material.

6. The process of claim 1, wherein the article comprises a nickel-based alloy a cobalt-based alloy, an iron-based alloy, and combinations thereof.

7. The process of claim 1, wherein the thermal barrier coating is porous.

8. The process of claim 1, wherein the alumina powder has a composition of at least 87 weight percent alumina based on the total weight of the alumina-based coating.

9. A turbine component having a coating applied by the coating method of claim 1.

10. A coating system, comprising:

a thermal barrier coating comprising a chemically stabilized zirconia material disposed on a metallic component; and

a thermally sprayed alumina-based coating disposed on the thermal barrier coating, wherein the alumina-based coating comprises at least 87 weight percent alumina based on a total weight of the alumina-based coating, the alumina-based coating having a thickness effective to elevate a melting point of a contaminant composition comprising mixed calcium-magnesium-aluminum-silicon-oxide systems, and wherein the thermally sprayed alumina-based coating has an average surface roughness of less than 4.0 micrometers to 0.75 micrometers.

11. The coating system of claim 10, wherein the thermally sprayed coating is deposited by a high velocity oxygen fuel process.

12. The coating system of claim 10, wherein the thermally sprayed coating is deposited by a high velocity air plasma spray process.

13. The coating system of claim 10, wherein the thermal barrier coating is porous.

14. The coating system of claim 10, wherein the metallic component is a hot path gas component.

15. The coating system of claim 10, wherein the chemically stabilized zirconia comprises an yttria-stabilized zirconia, scandia-stabilized zirconia, calcia-stabilized zirconia, magnesia-stabilized zirconia, and combinations thereof.

16. The coating system of claim 10, wherein the metallic component comprises a nickel-based alloy a cobalt-based alloy, an iron-based alloy, and combinations thereof.

17. The coating system of claim 10, wherein the alumina powder has a composition of at least 87 weight percent alumina based on the total weight of the alumina-based coating.