Calcium-magnesium alumino-silicate (CMAS) resistant thermal barrier coatings, systems, and methods of production thereof

Abstract

The thermal barrier coating includes reactive gadolinia in its microstructures and the embedded gadolinia effectively reacts with CMAS contaminant reducing the damage from CMAS. Moreover, a method to produce a CMAS resistant thermal barrier coating can include a post-treatment to the thermal barrier coating with the reactive gadolinia suspension in sol-gel state.

Claims

1. A calcium-magnesium alumino-silicate (CMAS) resistant thermal barrier coating comprising: a) a thermal barrier coating layer having a thickness; b) reactive gadolinia particles having a diameter between 10 and 200 nanometers, wherein the thermal barrier coating comprises a microstructure and wherein the reactive gadolinia particles are embedded in the microstructure for at least 50% of the thermal barrier coating layer thickness from the surface of the thermal barrier coating layer.

2. The thermal barrier coating of claim 1, wherein the thermal barrier coating layer is a ceramic coating layer comprising hafnia or fully or partially stabilized zirconia.

3. The thermal barrier coating of claim 1, wherein the microstructure comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries.

4. The thermal barrier coating of claim 1, wherein the thermal barrier coating layer is applied by plasma or combustion thermal spraying, suspension plasma spraying, or electron beam physical vapor deposition (EBPVD).

5. The thermal barrier coating of claim 1, wherein the thermal barrier coating thickness is between 1 mil and 250 mil.

6. The thermal barrier coating of claim 1, wherein the thermal barrier coating thickness is between 5 and 25 mil.

7. A coated article comprising: a) a substrate; b) a thermal barrier coating layer having a thickness; and c) reactive gadolinia nanoparticles; wherein the thermal barrier coating comprises a microstructure; and wherein the reactive gadolinia nanoparticles are embedded in the microstructure for at least 50% of the thermal barrier coating layer thickness from the surface of the thermal barrier coating layer; and wherein the coated article is one of a turbine fuel nozzle guide, a combustion chamber liner, a transition duct, a blade, a vane, or blade outer air seal.

8. The article of claim 7, wherein the thermal barrier coating layer is a ceramic coating layer comprising hafnia or fully or partially stabilized zirconia.

9. The article of claim 7, wherein the microstructure comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries.

10. The article of claim 7, wherein the thermal barrier coating layer is applied by plasma or combustion thermal spraying, suspension plasma spraying, or electron beam physical vapor deposition (EBPVD).

11. The article of claim 7, wherein the thermal barrier coating thickness is between 1 mil and 250 mil.

12. The article of claim 7, wherein the thermal barrier coating thickness is between 5 and 25 mil.

13. A calcium-magnesium alumino-silicate (CMAS) resistant thermal barrier coating consisting of: a) a thermal barrier coating layer having a microstructure and a thickness; b) reactive gadolinia particles having a diameter between 10 and 200 nanometers, and wherein the reactive gadolinia particles are embedded in the microstructure for at least 50% of the thermal barrier coating layer thickness from the surface of the thermal barrier coating layer.

14. The thermal barrier coating of claim 13, wherein the thermal barrier coating layer is a ceramic coating layer of hafnia or fully or partially stabilized zirconia.

15. The thermal barrier coating of claim 13, wherein the microstructure has at least one of cracks, pores, and inter-particle boundaries.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated in the accompanying drawings which are given herein below by way of illustration only, and thus are not limitative of the present invention, and wherein:

(2) FIG. 1 is a schematic view of a CMAS resistant thermal barrier coating.

(3) FIG. 2 shows an exemplary diagram of steps for producing a CMAS resistant thermal barrier coating.

(4) It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

DETAILED DESCRIPTION

(5) The present invention provides a novel thermal barrier coating system which prevents damage from CMAS environmental contaminants. The TBC of the present invention comprises reactive gadolinia embedded in the microstructure, or deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating. The reactive gadolinia in the invention is capable of reacting with CMAS contaminants further eliminating damages by CMAS contaminants.

(6) The present invention will be more illustrated by reference to the definitions set forth below in the drawing and context of the following detailed description.

Definitions

(7) As used herein the term thermal barrier coating (TBC) layer refers to a high performance coating material applied on the metallic surface of gas turbine engine components which operate at highly elevated temperature. The TBC may include a single coating layer or multiple layers. In certain embodiments, the TBC layer includes, but not is not limited to, a ceramic coating layer which comprises hafnia or fully or partially stabilized zirconia. In particular embodiments, the stabilized zirconia can include, without limitation, yttria-stabilized-zirconia (YSZ), magnesia-stabilized-zirconia, calcia-stabilized-zirconia, ceria-stabilized-zirconia, or a combination thereof. In other embodiments, the TBC layer is applied by plasma or combustion thermal spraying, suspension plasma spraying, or electron beam physical vapor deposition (EBPVD).

(8) As used herein, gadolinia refers to a rare earth inorganic compound comprising gadolinium and oxygen. In certain embodiments, the gadolinia is a reactive material to react with CMAS debris. In other embodiments, the gadolinia is in the form of one or more nanoparticles.

(9) As used herein the term microstructure refers to a minor vacant subunit which is introduced in a coating layer as part of the standard TBC procedure or intentionally by the process of coating application. In certain embodiments, the microstructure in the thermal barrier coating comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries.

(10) CMAS Resistant Thermal Barrier Coatings

(11) In one embodiment, this invention provides a CMAS resistant thermal barrier coating comprising a thermal barrier coating layer and a reactive gadolinia. In other embodiments, the microstructure in the thermal barrier coating comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries. The reactive gadolinia is embedded in the microstructure, or deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating to protect the coating from CMAS contaminant.

(12) The thermal barrier coating is intended to be used for controlling heat transfer and thermal stress which are transferred to the metallic base. In order to manage the heat flow efficiently, the materials for TBC may require several properties, such as insulating, matching thermal expansion coefficient or resistance to corrosion or to erosion. In such criteria, a ceramic material is a typically used for thermal barrier coating topcoat. In certain embodiments of the invention, the CMAS resistant thermal barrier coating comprises a ceramic coating layer comprising hafnia or fully or partially stabilized zirconia. In particular embodiments, the stabilized zirconia can include, without limitation, yttria-stabilized-zirconia (YSZ), magnesia-stabilized-zirconia, calcia-stabilized-zirconia, ceria-stabilized-zirconia, or a combination thereof.

(13) In certain embodiments, the microstructure in the thermal barrier coating comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries. Such microstructures in the thermal barrier coating may be introduced as part of the standard thermal barrier coating procedure or intentionally by the process of coating application. For example, the ceramic coating material contains porosity which may not be avoidable during coating deposit. In another example, cracks can be introduced during the deposition, e.g., due to change of temperature. Such microstructure is a key contributor in the present invention, particularly to improve CMAS resistance of the thermal barrier coating.

(14) In certain embodiments, the reactive gadolinia is embedded in the microstructure, or deposited on the surface of the microstructure of the thermal barrier coating. Such reactive gadolinia may infiltrate the thermal barrier coating through the microstructures, where the gadolinia reacts with penetrating CMAS contaminants. As results, such CMAS contaminants have increased viscosity and melting point further to not cause damages by precipitating in the thermal barrier coating.

(15) FIG. 1 depicts a schematic view of a CMAS resistant thermal barrier coating of the invention. A single thermal barrier coating layer 100 is deposited on a substrate 130 with various microstructures, such as cracks 110 and pores 120. The microstructures in TBC layer embed particles of reactive gadolinia in their inner spaces. The reactive gadolinia particles can be further deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating.

(16) In other embodiments, the reactive gadolinia may also be deposited on the surface of the thermal barrier coating to contact with CMAS contaminant.

(17) In other embodiments, the reactive gadolinia is in the form of one or more nanoparticles. In other embodiments, the size of the gadolinia nanoparticles is not particularly limited, but may be between about 1 nm and 500 nm in diameter, between about 5 nm and 300 nm in diameter, or between about 5 nm and 200 nm in diameter.

(18) In yet certain embodiment, the CMAS resistant thermal barrier coating is, without limitation, between about 1 mil and 250 mil, between about 3 mil and 100 mil, or between about 5 mil and 25 mil in thickness. According to the invention, the gadolinia may infiltrate entire thermal barrier coating layer to the bottom of the layer or maybe at least a top portion from the surface. The distribution of gadolinia infiltration in thermal barrier coating layer may vary depending on total thickness of coating, condition of treating with the gadolinia suspension, content of the gadolinia suspension, size of gadolinia particle and the like. In this regard, the thickness of thermal barrier coating may be optimized to effect distribution of gadolinia, physical properties of thermal barrier coating, effectiveness for CMAS resistance, or cost of raw material of gadolinia.

(19) Gadolinia Sol Treatment

(20) According to the present invention, the reactive gadolinia is introduced to the microstructure of the thermal barrier coating layer by gadolinia sol treatment.

(21) In certain embodiments, the reactive gadolinia is suspended in a solvent to make a reactive gadolinia suspension in sol state. In particular embodiments, the reactive gadolinia is in the form of one or more nanoparticles. The suspension is generally prepared by combining the reactive gadolinia nanoparticles with a suspension solvent. In certain embodiments, the suspension solvent, may be any solvent having a viscosity of lower than 100 centipoise, lower than 50 centipoise, or lower than 20 centipoise. In particular embodiments, the suspension solvent is, but is not limited to, water, acetic acid, benzene, tetrachloromethane, pentane, ethyl ether, methyl t-butyl ether, hexane, acetone, triethylamine, acetonitrile, heptane, methyl ethyl ketone, cyclopentane, dichloromethane, n-butyl chloride, ethyl acetate, glyme, iso-octane, methyl n-propyl ketone, tetrahydrofuran, chloroform, methyl isobutyl ketone, methanol, toluene, 1,1,2-trichlorotrifluoroethane, n-butyl acetate, ethylene dichloride, chlorobenzene, methyl isoamyl ketone, xylene, n,n-dimethylformamide, trifluoroacetic acid, pyridine, cyclohexane, ethyl alcohol, o-dichlorobenzene, 1,4-dioxane, n-methylpyrrolidone, 2-methoxyethanol, dimethyl acetamide, dimethyl formamide, dimethyl sulfoxide, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, isopropyl myristate, petroleum ether, propylene carbonate, 1,2,4-trichlorobenzene, or a mixture thereof. The sol state suspension would be understood by one of ordinary skill in the art to have dense concentration of gadolinia nanoparticle and high viscosity.

(22) In certain embodiments, the reactive gadolinia suspension may contain between about 1% and 90% by weight of the reactive gadolinia nanoparticles, between about 5% and 80% by weight of the reactive gadolinia nanoparticles, between about 10% and 50% by weight of the reactive gadolinia nanoparticles, or between about 10% and 25% by weight of the reactive gadolinia nanoparticles based on the weight of the suspension. With respect of the gadolinia content, the suspension with the highest range of gadolinia content may be in a gel state.

(23) According to the invention, the thermal barrier coating is treated with the gadolinia sol suspension to infiltrate the TBC with gadolinia particles. In certain embodiments, the method of infiltrating comprises dipping, painting, spraying, or pressure infiltrating with the reactive gadolinia suspension. In fact, the reactive gadolinia suspension penetrates microstructures in the thermal barrier coating by capillary action and transports the gadolinia. In other certain embodiments, the method further comprises repeating the step of treating the thermal barrier coating layer to achieve the desired content of gadolinia. The suspension solution evaporates at the end of process.

(24) In other certain embodiments, the method further comprises repeating the step of treating the thermal barrier coating layer to achieve the desired content of gadolinia. In particular embodiments, the treating step is performed two, three, five, or ten times to achieve the desired content of gadolinia.

(25) According to the invention, gadolinia sol treatment is an efficient technique to incorporate the reactive gadolinia to the thermal barrier coating. For instance, incorporating ratio of gadolinia particle with the gadolinia suspension is almost 100%. To the contrast, plasma spray coating provides only about 20% of gadolinia incorporation ratio from powder to gadolinia incorporated in thermal barrier coating.

(26) Method of Preparation

(27) The present invention provides a method to produce a CMAS resistant thermal barrier coating.

(28) In one embodiment, the method comprises steps of:

(29) a) applying an thermal barrier coating layer on a substrate;

(30) b) preparing a reactive gadolinia suspension; and

(31) c) treating the thermal barrier coating layer with the reactive gadolinia suspension,

(32) wherein the thermal barrier coating layer comprises a microstructure; and

(33) wherein a reactive gadolinia is embedded in the microstructure, or deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating. In certain embodiments, the thermal barrier coating can be a ceramic coating layer comprising hafnia or fully or partially stabilized zirconia. In particular embodiments, the stabilized zirconia can include, without limitation, yttria-stabilized-zirconia (YSZ), magnesia-stabilized-zirconia, calcia-stabilized-zirconia, ceria-stabilized-zirconia, or a combination thereof.

(34) In certain another embodiments, the thermal barrier coating layer is applied by plasma or combustion thermal spraying, suspension plasma spraying, or electron beam physical vapor deposition (EBPVD).

(35) In certain embodiments, the microstructure in the thermal barrier coating comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries. Such microstructures in the thermal barrier coating may be introduced as part of the standard thermal barrier coating procedure or intentionally by the process of coating application.

(36) In certain embodiments, the reactive gadolinia suspension is prepared by combining reactive gadolinia with the suspension solvent. In certain embodiments, the suspension solvent has a viscosity of lower than 100 centipoise, lower than 50 centipoise, or lower than 20 centipoise. In particular embodiments, the suspension solvent is, but is not limited to, water, acetic acid, benzene, tetrachloromethane, pentane, ethyl ether, methyl t-butyl ether, hexane, acetone, triethylamine, acetonitrile, heptane, methyl ethyl ketone, cyclopentane, dichloromethane, n-butyl chloride, ethyl acetate, glyme, iso-octane, methyl n-propyl ketone, tetrahydrofuran, chloroform, methyl isobutyl ketone, methanol, toluene, 1,1,2-trichlorotrifluoroethane, n-butyl acetate, ethylene dichloride, chlorobenzene, methyl isoamyl ketone, xylene, n,n-dimethylformamide, trifluoroacetic acid, pyridine, cyclohexane, ethyl alcohol, o-dichlorobenzene, 1,4-dioxane, n-methylpyrrolidone, 2-methoxyethanol, dimethyl acetamide, dimethyl formamide, dimethyl sulfoxide, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, isopropyl myristate, petroleum ether, propylene carbonate, 1,2,4-trichlorobenzene, or a mixture thereof.

(37) In certain embodiments, the reactive gadolinia is in the form of one or more nanoparticles. In other certain embodiments, the size of the gadolinia nanoparticles is not particularly limited, but may be between about 1 nm and 500 nm, between about 5 nm and 300 nm or between about 10 nm and 200 nm in diameter.

(38) In certain embodiments, the reactive gadolinia suspension may contain between about 1% and 90% by weight of the reactive gadolinia nanoparticles, between about 5% and 80% by weight of the reactive gadolinia nanoparticles, between about 10% and 50% by weight of the reactive gadolinia nanoparticles, or between about 10% and 25% by weight of the reactive gadolinia nanoparticles based on the weight of the suspension.

(39) The method of infiltrating can include dipping, painting, spraying, or pressure infiltrating with the reactive gadolinia suspension. It is also contemplated that the method can further include evaporating the suspension solvent.

(40) In other certain embodiments, the method further comprises repeating the step of treating the thermal barrier coating layer to achieve the desired content of gadolinia. In particular embodiments, the treating step is performed two, three, five, or ten times to achieve the desired content of gadolinia.

(41) In another embodiments, the CMAS resistant thermal barrier coating produced by the method can be, without limitation, between about 1 mil and 250 mil, between about 3 mil and 100 mil, or between about 5 mil and 25 mil in thickness.

(42) The disclosed methods can be advantageous to provide a CMAS resistant thermal barrier coating produced by a single treatment process. This eliminates further application of CMAS-protective layers and reduces processing time and cost.

(43) Articles

(44) In addition, this invention provides an article coated with a CMAS resistant thermal barrier coating layer, which comprises a reactive gadolinia. The thermal barrier coating includes microstructures comprising a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries. The reactive gadolinia is embedded in the microstructure, or deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating to protect the coating from the CMAS contaminant. The article coated with a CMAS resistant thermal barrier coating is particularly improved with respect to CMAS resistance.

(45) In one embodiment, the article may comprise;

(46) a) a substrate;

(47) b) a thermal barrier coating layer; and

(48) c) a reactive gadolinia;

(49) wherein the thermal barrier coating layer comprises a microstructure; and

(50) wherein the reactive gadolinia is embedded in the microstructure, or deposited on the surface of the microstructure, or deposited on the surface of the thermal barrier coating.

(51) In certain embodiments, the article with the CMAS resistant thermal barrier coating operates at highly elevated temperature. Such article is, but not limited to, a turbine fuel nozzle, fuel nozzle guide, combustion chamber liner, transition duct, blade, vane or blade outer air seal.

(52) In other embodiments, the thermal barrier coating comprises a ceramic coating layer comprising hafnia or fully or partially stabilized zirconia. In particular embodiments, the stabilized zirconia can include, without limitation, yttria-stabilized-zirconia (YSZ), magnesia-stabilized-zirconia, calcia-stabilized-zirconia, ceria-stabilized-zirconia, or a combination thereof.

(53) In certain embodiments, the microstructure in the thermal barrier coating comprises a ceramic matrix with at least one of cracks, pores, and inter-particle boundaries. Such microstructures may be introduced as part of the standard thermal barrier coating procedure or intentionally by the process of coating application.

(54) In other embodiments, the reactive gadolinia in the article is in the form of one or more nanoparticles, of which the size of the gadolinia nanoparticles is not particularly limited, but may be between about 1 nm and 500 nm, between about 5 nm and 300 nm or between about 10 nm and 200 nm in diameter.

(55) In certain other embodiments, the article which is treated according to the methods of the invention to produce the thermal barrier coating layer are further coated with an additional layer of material to provide an additional property.

(56) Other multilayered or segmented coating layers may be applied on the CMAS resistant thermal barrier coating of the present invention for other protective reasons. Likewise, the CMAS resistant thermal barrier coating of the present invention may be applied on the other coating layers for other technical improvements.

Example

(57) FIG. 2 shows an exemplary diagram of steps for producing a CMAS resistant thermal barrier coating.

(58) A thermal barrier coating layer is applied on a blade outer air seal by electron beam physical vapor deposition (EBPVD) under standard conditions. The thermal barrier coating is composed of a ceramic coating matrix comprising yttria-stabilized-zirconia (YSZ). The normal thickness of this thermal barrier coating is about 20 mil.

(59) A slurry gadolinia nanoparticle is prepared by mixing the gadolinia nanoparticles with a 50:50 mixture by volume of water and ethanol. The slurry suspension solution contains about 25% by weight of reactive gadolinia nanoparticles based on the total weight of the suspension solution. The size of the gadolinia nanoparticles in the slurry suspension is about 10-100 nm in diameter (US Research Nanomaterials, Inc., Houston, Tex., USA).

(60) After optionally cleaning the surface of the thermal barrier coating layer, the slurry gadolinia nanoparticle suspension is applied on the surface of the thermal barrier coating layer by paint brush. Meanwhile, the elevated pressure, e.g. 10 MPa, is applied after painting with the slurry suspension for pressure infiltrating. Once the slurry suspension infiltrates the thermal barrier coating layer, the suspension solvent evaporates at room temperature. After the solvent evaporates, the same cycle of treatment with the slurry gadolinia nanoparticle suspension is repeated for about 10 times, until gadolinia nanoparticles incorporates in the thermal barrier coating at least 50% of top portion from the surface.

(61) The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.