Method for preparing environmental barrier coating, method for sealing pores in ceramic matrix composite and / or environmental barrier coating, and composite structure

Abstract

To provide an improved environmental barrier coating (EBC) system.SOLUTION: There is provided an environmental barrier coating (EBC) having one or more sealing layers incorporated to inhibit ingress of a corrosive material into the EBC and associated ceramic material (CMC). The sealing layer is a layer of yttrium oxide (Y2O3), lanthanum oxide (La2O3), ytterbium oxide (Yb2O3), hafnium oxide (HfO2), zirconium oxide (ZrO2), hafnium silicon oxide (HfSiO4), zirconium silicon oxide (ZrSiO4), ytterbium silicon oxide (Yb2Si2O7), and / or aluminum oxide (Al2O3), and is formed by atomic layer deposition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to environmental barrier coatings (EBCs) used for the protection of ceramic matrix materials (CMCs) and methods for making the same. [Background technology]

[0002] Ceramic matrix materials (CMCs) are often used in applications that experience high heat environments, such as high-temperature components in gas turbine engines and heat shield systems used in spacecraft re-entry. While these materials can withstand high temperatures, they degrade over time due to the effects of corrosive forces. For example, in CMCs containing silicon, the silicon is susceptible to volatilization in the presence of high-temperature water vapor. The resulting loss of silicon leads to crack formation and degradation of the CMC, ultimately leading to failure of components formed from the CMC.

[0003] Environmental barrier coating systems are used to protect CMCs from harsh environments and the associated corrosive forces. For example, EBCs reduce the surface and interior exposure of CMCs to hot water vapor (by penetration through pores and cracks), thereby reducing CMC degradation and extending the operational life of components made from CMCs.

[0004] EBCs are typically multi-layered. For example, an EBC may be a two-layer system consisting of an initial bond coat and a top coat applied to the surface of a CMC substrate. Other EBC systems may have more layers, such as multiple bond coat and top coat layers, or a bond coat layer, an inner top coat layer, and an outer top coat layer.

[0005] The EBC itself may be susceptible to penetration of hot steam, which can lead to eventual failure of the EBC system. For example, the EBC layer may exhibit pores and / or cracks that allow hot water vapor to penetrate therein, inducing degradation of the EBC system and potentially allowing the hot steam to reach the CMC substrate.

[0006] There is a need to provide new EBC systems that exhibit improved capabilities to inhibit degradation and increase the operational life of components made from CMCs, as well as new methods for manufacturing EBC systems with such improved capabilities. Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to improve an EBC system of the kind mentioned at the outset so that the above-mentioned disadvantages are reduced. [Means for solving the problem]

[0008] Broadly, this disclosure relates to providing a relatively thin sealing layer on one or more layers of an EBC system, or between a substrate and an EBC system, using atomic layer deposition (ALD) to seal pores and / or cracks and / or promote adhesion. The disclosure also relates to improvements in inhibiting the ingress of corrosive materials into EBCs and their associated CMCs using sealing layers coated by atomic layer deposition.

[0009] According to one embodiment of the present disclosure, there is provided a method for preparing an environmental barrier coating (EBC), comprising: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; and b) a topcoat comprising one or more layers is applied to the coated CMC substrate; at least one sealing layer is disposed (i) between the bond coat and the CMC substrate, (ii) between the bond coat and the top coat, (iii) between layers of the bond coat, (iv) between layers of the top coat, and / or (v) on top of the top coat; At least one sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the at least one sealing layer is coated by atomic layer deposition.

[0010] According to a further embodiment of the present disclosure, there is provided a method of sealing pores in a ceramic matrix composite and / or an environmental barrier coating (EBC), comprising: coating at least one sealing layer by atomic layer deposition on a surface of a ceramic matrix composite (CMC) substrate or on a layer of an environmental barrier coating (EBC); Methods are provided wherein the at least one sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer.

[0011] According to another embodiment of the present disclosure, there is provided a composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over a CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; d) at least one sealing layer, the sealing layer being (i) between the bond coat and the CMC substrate, (ii) between the bond coat and the top coat, (iii) between layers of the bond coat, (iv) between layers of the top coat, and / or (v) coated on top of the top coat; A composite structure is provided, wherein at least one sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and wherein the at least one sealing layer is coated by atomic layer deposition.

[0012] In some embodiments, at least one sealing layer is coated between the bond coat and the CMC substrate. Additionally or alternatively, in some embodiments, at least one sealing layer is coated between the bond coat and the top coat. Additionally or alternatively, in some embodiments, the bond coat comprises multiple layers, and at least one sealing layer is coated between layers of the bond coat. Furthermore, additionally or alternatively, in some embodiments, the top coat comprises multiple layers, and at least one sealing layer is coated between layers of the top coat. Furthermore, additionally or alternatively, in some embodiments, at least one sealing layer is coated on top of the top coat.

[0013] In some embodiments, the at least one sealing layer has a thickness of 0.05 to 2 μm. For example, the thickness can be less than 1 μm, or less than 0.2 μm.

[0014] In some embodiments, at least one sealing layer of yttrium oxide (YO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of lanthanum oxide (LaO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of ytterbium oxide (YbO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of hafnium oxide (HfO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of zirconium oxide (ZrO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of hafnium silicon oxide (HfSiO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of zirconium silicon oxide (ZrSiO) is deposited by ALD. Additionally or alternatively, at least one sealing layer of ytterbium silicon oxide (Yb2Si2O7) is deposited by ALD. Additionally or alternatively, at least one sealing layer of aluminum oxide (Al2O3) is deposited by ALD.

[0015] Furthermore, in some embodiments, the CMC substrate is a SiC / SiC ceramic matrix composite or a silicon nitride ceramic matrix composite. Also, in some embodiments, the bond coat material is a silicon-based material. Furthermore, in some embodiments, the top coat of the EBC comprises an oxide selected from ZrO2, HfO2, HfSiO4, RE2SiO5, RE2SiO7, and / or RE2O3, where RE is a rare earth metal (i.e., RE is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu).

[0016] Additionally, in some embodiments, layers of the EBC other than at least one sealing layer are coated by atmospheric pressure plasma spray (APS), low pressure plasma spray (LPPS), chemical vapor deposition (CVD), physical vapor deposition (PVD), electron beam physical vapor deposition (EB-PVD), or plasma spray physical vapor deposition (PS-PVD), polymer deposition, or slurry coating.

[0017] Implementation of the inventive concepts disclosed herein may be better understood by consideration of the following detailed description. Such description refers to the accompanying drawings, which are not necessarily to scale and in which some features may be exaggerated, some features omitted, or represented diagrammatically for clarity. Like reference numbers in the drawings may represent and refer to the same or similar elements, features, or functions. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a cross-sectional side view of a CMC substrate with a bond coat and a sealing layer on a surface of the CMC substrate between the CMC substrate and the bond coat. [Figure 2] FIG. 1 is a cross-sectional side view of a CMC substrate comprising a bond coat and a top coat, with a sealing layer on a surface of the bond coat layer between the bond coat and the top coat. [Figure 3] FIG. 1 is a cross-sectional side view of a CMC substrate having a multi-layer bond coat and a top coat with a sealing layer disposed between the layers of the multi-layer bond coat. [Figure 4] FIG. 1 is a cross-sectional side view of a CMC substrate comprising a bond coat and a multi-layer top coat with a sealing layer disposed between the layers of the multi-layer top coat. [Figure 5] 1 is a cross-sectional side view of a CMC substrate having a bond coat and a multi-layer top coat with a sealing layer applied to the surface of the top coat. DETAILED DESCRIPTION OF THE INVENTION

[0019] Before describing in detail at least one embodiment of the inventive concepts disclosed herein, it is to be understood that the inventive concepts are not limited in their application to the details of construction and the arrangement of components, or to the steps or methodologies set forth in the following description or illustrated in the drawings. In the following detailed description of embodiments of the inventive concepts, numerous specific details are set forth in order to provide a more thorough understanding of the inventive concepts. It will be apparent, however, to one skilled in the art having the benefit of this disclosure, that the inventive concepts disclosed herein may be practiced without these specific details.

[0020] Broadly, embodiments of the inventive concept include those in which the CMC substrate comprises an EBC, and the composite structure of the CMC substrate and the EBC comprises one or more sealing layers coated by atomic layer deposition (ALD). The sealing layer can improve the durability of the EBC by filling pores and / or cracks in the CMC, bond coat, and / or top layer to more effectively inhibit the flow of oxidizers to the EBC and CMC. Additionally, the sealing layer can provide a seal between layers to more effectively inhibit the flow of oxidizers to the EBC and CMC. The ALD layer can also interact with, for example, the bond coat material to form a more stable composite system.

[0021] In some embodiments, a sealing layer is applied between the CMC substrate and the bond coat. For example, as shown in FIG. 1 , a composite structure includes a CMC substrate 10, a bond coat 20, and a top coat 30. The bond coat 20 aids in adhesion between the substrate 10 and the top coat 30. A sealing layer 40 is applied to the surface of the substrate 10 by ALD. The sealing layer 40 acts to modify the CMC substrate / bond coat interface, sealing pores and / or cracks within the substrate 10. Furthermore, in some embodiments, the sealing layer 40 can also aid in adhesion of the bond coat 20 to the substrate 10.

[0022] The sealing layer is an yttrium oxide, lanthanum oxide, hafnium oxide, zirconium oxide, hafnium silicon oxide, zirconium silicon oxide, ytterbium oxide, and / or aluminum oxide layer deposited by atomic layer deposition (ALD). In some embodiments, the sealing layer is fabricated from only one of these oxides. In other embodiments, the sealing layer comprises an alternating composition (e.g., nanolaminate) selected from YO, La, Yb, HfO, ZrO, HfSiO, ZrSiO, YbSiO, and AlO.

[0023] ALD is a deposition technique that allows for the deposition of ultrathin, conformal, dense films onto surfaces. In general, the advantages of ALD include its ability to provide uniform deposition of layers, its ability to control layer thickness, and its ability to provide deposition of layers on complex, three-dimensional surfaces.

[0024] Generally, in an ALD process, a substrate is placed in a chamber at an appropriate temperature and pressure, followed by sequential injection of precursor materials into the chamber, optionally with purging between injections. For example, to deposit a metal oxide film by an ALD process, two precursors are typically used, with one precursor acting as a metal source and the other as an oxygen source. The precursors react with the surface to be coated, and a thin film is deposited by repeated exposure to the two separate precursors.

[0025] Precursors used in the ALD of yttrium oxide, lanthanum oxide, ytterbium oxide, hafnium oxide, zirconium oxide, hafnium silicon oxide, zirconium silicon oxide, ytterbium silicon oxide, or aluminum oxide are known in the art. For example, suitable ALD precursors for aluminum oxide layers include trimethylaluminum (TMA) and water, or TMA and ozone. For yttrium oxide layers, suitable ALD precursors include tris(ethylcyclopentadienyl)yttrium and water, or tris(methylcyclopentadienyl)yttrium and water. For hafnium oxide layers, suitable ALD precursors include tetrakis(dimethylamido)hafnium and water. For zirconium oxide ALD, suitable precursors include water and ZrCl4, Zr(OEt2)4, or Cp2Zr(CH3)2 (where Et = ethyl and Cp = cyclopentadienyl). Lanthanum oxide precursors for ALD include La(thd)3 (thd is 2,2,6,6-tetramethyl-3,5-heptane-dione), La(Cp)3 (Cp = cyclopentadienyl), and La(iPrCp)3 (iPrCp = isopropylcyclopentadienyl) and water or ozone. For ytterbium oxide, suitable ALD precursors include Yb(C5H5)3 and HO and / or O3. Suitable silica precursors for Si-containing layers include tetraethoxysilane Si(C2H5O)4, tetraisocyanatosilane, silicon(IV) chloride and water, as well as tri-t-butoxysilanol and TMA.

[0026] Mixed oxide layers, such as hafnium silicon oxide and ytterbium silicon oxide, can be achieved using a supercycle approach. The composition can be altered by adjusting the cycle ratio and order of each process within the supercycle. For example, a homogeneous film (ABzOw) can be produced by regularly alternating between the two-fluid cycles AOx and BOy. Alternatively, a multilayer film of AOx and BOy, also known as a nanolaminate, can be obtained by repeating each two-fluid cycle multiple times. For more information on ALD using supercycles, see, for example, M. Coll et al., “Atomic layer deposition of functional multicomponent oxides,” APL Materials, vol. 7, issue 11, November 2019.

[0027] Additional examples of precursors are described, for example, in R.W. Johnson et al. "A brief review of atomic layer deposition: from fundamentals to applications," Materials Today, vol. 17, issue 5, June 2014, pages 236-246.

[0028] ALD is carried out at lower temperatures than CVD (chemical vapor deposition). Generally, the temperature for carrying out an ALD reaction is generally less than 400°C, such as less than 350°C, for example, between 120°C and 300°C.

[0029] The thickness of the sealing layer can be varied by varying the number of successive applications of precursors to the substrate during the ALD process. In some embodiments, the sealing layer has a thickness of, for example, 0.05 to 2 μm, e.g., less than 1 μm, or less than 0.2 μm, or 0.2 to 1 μm.

[0030] The sealing layer can be used with any CMC substrate provided with an EBC. In some embodiments, the substrate is a SiC / SiC ceramic matrix composite or a silicon nitride ceramic matrix composite. For example, a SiC / SiC ceramic matrix composite can have a SiC matrix fabricated by chemical vapor infiltration (CVI). Alternatively, the SiC matrix can be fabricated by infiltration of a Si-containing preceramic polymer via a polymer infiltration and pyrolysis (PIP) process. In other cases, the SiC matrix can be fabricated by melt infiltration of Si or a Si alloy that reacts with a carbon-containing material to form SiC. In other embodiments, the matrix can include an oxide material.

[0031] Except for the one or more sealing layers, the other layers of the EBC can be coated onto the CMC substrate by a variety of processes, including atmospheric plasma spray (APS), low pressure plasma spray (LPPS), chemical vapor deposition (CVD), physical vapor deposition (PVD), electron beam physical vapor deposition (EB-PVD), or plasma spray physical vapor deposition (PS-PVD), polymer deposition, and slurry coating. In some embodiments, the bond coat and / or top coat layers are coated by forming a slurry of the coating material using a solvent or carrier.

[0032] The bond coat material can vary, including, for example, silicon-based materials dispersed in a matrix, such as Si, SiO2, SiC, Si3N4, SiC x N y , or SiO x C y and other Si-based composites, such as SiC / SiO2 / glass oxide composite bond coats. Top coats can include a variety of materials, including ZrO2, HfO2, HfSiO4, RE2SiO5, RE2Si2O7 (e.g., Yb2Si2O7), and RE2O3 (where RE is a rare earth metal).

[0033] Referring to the method embodiment of FIG. 1, the method includes: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising one or more layers to the coated CMC substrate; c) applying a sealing layer between the bond coat and the CMC substrate; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0034] This method embodiment produces a composite structure, the composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over a CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; d) a sealing layer disposed between the bond coat and the CMC substrate; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0035] In the embodiment of FIG. 1, the pores of the ceramic matrix composite are sealed by depositing at least one sealing layer by ALD on the surface of the ceramic matrix composite (CMC) substrate, i.e., between the CMC and the EBC.

[0036] In some embodiments, a sealing layer is applied between the bond coat and the top coat. For example, as shown in FIG. 2 , a composite structure includes a CMC substrate 10, a bond coat 20, and a top coat 30. A sealing layer 40 is applied to the surface of the bond coat 20 by ALD. The sealing layer 40 acts to modify the bond coat / top coat interface, sealing pores and / or cracks in the bond coat 20. Furthermore, in some embodiments, the sealing layer 40 can also aid in the adhesion of the top coat 30 to the bond coat 20.

[0037] Thus, with reference to FIG. 2, this method embodiment includes: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising one or more layers to the coated CMC substrate; c) applying a sealing layer between the bond coat and the top coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0038] An embodiment of this method produces a composite structure, the composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over a CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; d) a sealing layer, the sealing layer being coated between the bond coat and the top coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0039] In the embodiment of FIG. 2, the pores of the bond coat are sealed by depositing at least one sealing layer by ALD on the surface of the bond coat of the EBC, i.e., between the bond coat and the top coat.

[0040] In some embodiments, a sealing layer is applied between layers of a multi-layer bond coat. For example, as shown in FIG. 3 , a composite structure includes a CMC substrate 10, multi-layer bond coats 50a and 50b, and a top coat 30. A sealing layer 40 is applied by ALD between layers 50a and 50b of the multi-layer bond coat. The sealing layer 40 acts at the interface between layers 50a and 50b of the multi-layer bond coat to seal pores and / or cracks within the bond coat. Furthermore, in some embodiments, the sealing layer 40 can also aid in adhesion between layers 50a and 50b of the multi-layer bond coat.

[0041] Thus, with reference to FIG. 3, this method embodiment includes: a) applying a bond coat comprising a plurality of layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising one or more layers to the coated CMC substrate; c) applying a sealing layer between the layers of bond coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0042] An embodiment of this method produces a composite structure, the composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising multiple layers over a CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; d) a sealing layer, the sealing layer being coated between the layers of bond coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0043] In the embodiment of FIG. 3, the pores of the bond coat layer are sealed by depositing at least one sealing layer on the surface of that layer, i.e., between that layer and another layer of the EBC bond coat, by ALD.

[0044] In some embodiments, a sealing layer is applied between layers of a multi-layer topcoat. For example, as shown in FIG. 4 , a composite structure includes a CMC substrate 10, a bond coat 20, and multi-layer topcoats 60a and 60b. A sealing layer 40 is applied by ALD between layers 60a and 60b of the multi-layer topcoat. The sealing layer 40 acts at the interface between layers 60a and 60b of the multi-layer topcoat to seal pores and / or cracks within the topcoat. Furthermore, in some embodiments, the sealing layer 40 can also aid in adhesion between layers 60a and 60b of the multi-layer topcoat 6.

[0045] Thus, with reference to FIG. 4, this method embodiment includes: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising multiple layers to the coated CMC substrate; c) applying a sealing layer between the layers of topcoat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0046] An embodiment of this method produces a composite structure, the composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over a CMC substrate; c) a top coat over the bond coat, the top coat comprising multiple layers; d) a sealing layer, the sealing layer being coated between the layers of topcoat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0047] In the embodiment of FIG. 4, the pores of the topcoat layer are sealed by depositing at least one sealing layer by ALD on the surface of that layer, i.e., between that layer and another layer of the EBC topcoat.

[0048] In some embodiments, a sealing layer is applied on top of the topcoat. For example, as shown in Figure 5, a composite structure includes a CMC substrate 10, a bond coat 20, and a topcoat 03. A sealing layer 40 is applied on top of the topcoat 30 by ALD. The sealing layer 40 acts on the surface of the topcoat 30 to seal pores and / or cracks within the top surface of the topcoat 30.

[0049] Thus, with reference to FIG. 5, this method embodiment includes: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising one or more layers to the coated CMC substrate; c) applying a sealing layer on top of the top coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0050] An embodiment of this method produces a composite structure, the composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over a CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; d) a sealing layer coated on top of the top coat; The sealing layer is an yttrium oxide (YO), lanthanum oxide (LaO), ytterbium oxide (YbO), hafnium oxide (HfO), zirconium oxide (ZrO), hafnium silicon oxide (HfSiO), zirconium silicon oxide (ZrSiO), ytterbium silicon oxide (YbSiO), and / or aluminum oxide (AlO) layer, and the sealing layer is coated by atomic layer deposition.

[0051] In the embodiment of FIG. 5, the pores on the top surface of the topcoat of the EBC are sealed by depositing at least one sealing layer on the top surface by ALD.

[0052] As an exemplary embodiment, a composite of the present disclosure may be a CMC substrate with a multilayer EBC including, for example, a HfSiO topcoat layer and a bond coat layer, where the bond coat is SiO-based and includes a silicate glass with additives such as Al, Mg, Ba, Ca, B, and / or Na. The bond coat may be deposited, for example, by a slurry process, resulting in pores present in the coating. The pores and cracks present in the bond coat may be sealed / filled using ALD with YO, La, Yb, HfO, ZrO, HfSiO, ZrSiO, YbSiO, and / or AlO, forming a layer, for example, 0.2-1 micron thick.

[0053] As a further exemplary embodiment, a composite of the present disclosure may be a CMC substrate with a multilayer EBC including, for example, a Yb2SiO7 topcoat layer and a bond coat layer, where the bond coat is SiO2-based and includes a silicate glass with additives such as Al, Mg, Ba, Ca, B, and / or Na. The bond coat is deposited, for example, by a slurry process, which results in pores present in the coating. The pores and cracks present in the bond coat are sealed / filled with YO3, La2O3, Yb2O3, HfO2, ZrO2, HfSiO4, ZrSiO4, Yb2SiO7, and / or Al2O3 using ALD, forming a layer, for example, 0.2-1 micron thick, by application of ALD.

[0054] As a further exemplary embodiment, a composite of the present disclosure may be a CMC substrate with a multilayer EBC including, for example, a HfSiO top coat and a bond coat, where the bond coat is SiO-based and includes a silicate glass with additives such as Al, Mg, Ba, Ca, B, and / or Na. Interfaces within the EBC (e.g., interfaces between layers of the bond coat, interfaces between layers of the top coat, and / or interfaces between the bond coat and top coat) are coated with a sealing layer to seal pores / cracks at the interface and promote adhesion between the layers. The sealing layer may include YO, La, Yb, Hf, Zr, HfSiO, ZrSiO, YbSiO, and / or AlO, and may be applied using ALD, forming a layer, for example, 0.2-1 micron thick by ALD deposition.

[0055] The corresponding structure, material, acts, and equivalents of all means or step-plus-function elements in the following claims are intended to include any structure, material, or acts for performing the function as specifically claimed in combination with other claimed elements. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the disclosed form. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described to best explain the principles of the invention and its practical application, and to enable others skilled in the art to understand the invention in embodiments with various modifications suited to the particular use contemplated.

[0056] Modifications and equivalents may be made to the features of the claims without departing from the spirit or scope of the invention. It is therefore intended that the present invention cover the modifications and variations disclosed above, provided they come within the scope of the claims and their equivalents.

Claims

1. 1. A method for preparing an environmental barrier coating, comprising: a) applying a bond coat comprising one or more layers to a ceramic matrix composite (CMC) substrate to provide a coated CMC substrate; b) applying a topcoat comprising one or more layers to the coated CMC substrate; at least one sealing layer is disposed (i) between the bond coat and the CMC substrate, (ii) between the bond coat and the top coat, (iii) between layers of the bond coat, (iv) between layers of the top coat, and / or (v) on top of the top coat; The at least one sealing layer is made of yttrium oxide (Y ２ O ３ ), lanthanum oxide (La ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), hafnium oxide (HfO ２ ), zirconium oxide (ZrO ２ ), hafnium silicon oxide (HfSiO ４ ), zirconium silicon oxide (ZrSiO ４ ), ytterbium silicon oxide (Yb ２ Si ２ O ７ ), and / or aluminum oxide (Al ２ O ３ ) layer, wherein the at least one sealing layer is coated by atomic layer deposition.

2. The method of claim 1 , wherein the at least one sealing layer is coated between the bond coat and the CMC substrate.

3. The method of claim 1 , wherein the at least one sealing layer is coated between the bond coat and the top coat.

4. The method of claim 1 , wherein the bond coat comprises multiple layers, and the at least one sealing layer is coated between layers of the bond coat.

5. The method of claim 1 , wherein the topcoat comprises multiple layers, and the at least one sealing layer is coated between layers of the topcoat.

6. The method of claim 1 , wherein the at least one sealing layer is coated on top of the top coat.

7. The method of claim 1, wherein the at least one sealing layer has a thickness of 0.2 to 1 μm.

8. The method of claim 1, wherein the at least one sealing layer has a thickness of 0.05 to 2 μm.

9. The at least one sealing layer is formed of yttrium oxide (YO 2 ) prepared by atomic layer deposition using tris(ethylcyclopentadienyl)yttrium and water or tris(methylcyclopentadienyl)yttrium and water as precursors. ２ O ３ 10. The method of claim 1, comprising:

10. The at least one sealing layer is La(2,2,6,6-tetramethyl-3,5-heptane-dione) ３ , La(cyclopentadienyl) ３ , or La(isopropylcyclopentadienyl) ３ and water or ozone as precursors. ２ O ３ 10. The method of claim 1, comprising:

11. The at least one sealing layer is hafnium oxide (HfO) produced by atomic layer deposition using tetrakis(dimethylamido)hafnium and water as precursors. ２ 10. The method of claim 1, comprising:

12. The at least one sealing layer is selected from the group consisting of ZrCl ４ , Zr(OEt ２ ) ４ , or Cp ２ Zr(CH ３ ) ２ and water as precursors to produce zirconium oxide (ZrO ２ 2. The method of claim 1, comprising:

13. The at least one sealing layer is Yb(C ５ H ５ ) ３ And, H ２ O and / or O ３ and hafnium ytterbium oxide (Yb ２ O ３ 10. The method of claim 1, comprising:

14. The at least one sealing layer is aluminum oxide (Al O ... ２ O ３ 10. The method of claim 1, comprising:

15. The CMC substrate is a SiC / SiC ceramic matrix composite or a silicon nitride ceramic matrix composite, the bond coat material is a silicon-based material, and the top coat is a ZrO ２ , HfO ２ , HfSiO ４ , R.E. ２ SiO ５ , R.E. ２ Si ２ O ７ , and / or RE ２ O ３ 10. The method of claim 1, wherein R E is a rare earth metal.

16. 10. The method of claim 1, wherein the layers of the EBC other than the at least one sealing layer are coated by atmospheric pressure plasma spray (APS), low pressure plasma spray (LPPS), chemical vapor deposition (CVD), physical vapor deposition (PVD), electron beam physical vapor deposition (EB-PVD), or plasma spray physical vapor deposition (PS-PVD), polymer deposition, or slurry coating.

17. 1. A method for sealing pores in a ceramic matrix composite and / or an environmental barrier coating (EBC), comprising: coating at least one sealing layer by atomic layer deposition on a surface of the ceramic matrix composite (CMC) substrate or on a surface of the layer of environmental barrier coating (EBC); The at least one sealing layer is made of yttrium oxide (Y ２ O ３ ), lanthanum oxide (La ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), hafnium oxide (HfO ２ ), zirconium oxide (ZrO ２ ), hafnium silicon oxide (HfSiO ４ ), zirconium silicon oxide (ZrSiO ４ ), ytterbium silicon oxide (Yb ２ Si ２ O ７ ), and / or aluminum oxide (Al ２ O ３ ) layer.

18. The method of claim 17, wherein the at least one sealing layer has a thickness of 0.05 to 2 μm.

19. A composite structure comprising: a) a ceramic matrix composite (CMC) substrate; b) a bond coat comprising one or more layers over the CMC substrate; c) a topcoat over the bond coat, the topcoat comprising one or more layers; and d) at least one sealing layer, the sealing layer being (i) between the bond coat and the CMC substrate, (ii) between the bond coat and the top coat, (iii) between layers of the bond coat, (iv) between layers of the top coat, and / or (v) coated on top of the top coat; The at least one sealing layer is made of yttrium oxide (Y ２ O ３ ), lanthanum oxide (La ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), hafnium oxide (HfO ２ ), zirconium oxide (ZrO ２ ), hafnium silicon oxide (HfSiO ４ ), zirconium silicon oxide (ZrSiO ４ ), ytterbium silicon oxide (Yb ２ Si ２ O ７ ), and / or aluminum oxide (Al ２ O ３ ) layer, wherein said at least one sealing layer is coated by atomic layer deposition.

20. 20. The composite structure of claim 19, wherein the at least one sealing layer has a thickness of 0.05 to 2 μm.

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