EBC for improved TGO and silicone-based bond coatings

Abstract

To provide improved TGO and EBC for silicone-based bond coatings. [Solution] A coated part (10) is provided, along with a method for forming it, comprising a silicon-containing substrate (12) having a surface (14), a bond coat (16) on the surface (14) of the silicon-containing substrate (12) which contains silicon, a thermally grown oxide layer (20) on the bond coat (16) which contains borosilicate glass (24) and a mullite-based material (28), and an environmental shielding coating (18) on the thermally grown oxide layer (20).

Description

Technical Field

[0001] The present disclosure generally relates to environmental barrier coatings for coated components and to methods of forming the coated components.

Background Art

[0002] Silicon-based materials are used for high-temperature components of gas turbine engines such as airfoils (e.g., blades, vanes), combustor liners, and shrouds. Silicon-based materials can include silicon-based monolithic ceramic materials, intermetallic materials, and composite materials. For example, a silicon-based ceramic matrix composite (CMC) can include silicon-containing fibers that reinforce a silicon-containing matrix phase.

Summary of the Invention

Means for Solving the Problems

[0003] The complete and enabling disclosure of the present disclosure directed to those skilled in the art, including the best mode of the present invention, is set forth herein with reference to the accompanying drawings.

Brief Description of the Drawings

[0004] [Figure 1] It is a schematic cross-sectional view of an example coated component including a silicon-containing substrate coated with a bond coat and an environmental barrier coating. [Figure 2] It is a schematic cross-sectional view of an example coated component including a silicon-containing substrate coated with a bond coat, a thermally grown oxide layer in the bond coat, and an environmental barrier coating. [Figure 3] It is a diagram of an example method of forming the coated component described herein.

Mode for Carrying Out the Invention

[0005] In this specification, the term “example” means “provided as an example, example, or illustration.” Any implementation described herein as an “example” shall not necessarily be construed as preferable or advantageous to any other implementation. Furthermore, unless otherwise expressly specified, all embodiments described herein should be considered examples.

[0006] The singular forms "a, an" and "the" imply a plural noun unless the context explicitly indicates otherwise.

[0007] For example, in the context of "at least one of A, B, and C," the phrase "at least one of ~" refers to A only, B only, C only, or any combination of A, B, and C.

[0008] As used herein, terms such as “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of any individual component.

[0009] Chemical elements are discussed in this disclosure using their common chemical abbreviations, such as those commonly found in the periodic table. For example, hydrogen is represented by its common chemical abbreviation H, and helium by its common chemical abbreviation He. As used herein, “RE” refers to rare earth elements or mixtures of rare earth elements. More specifically, “RE” refers to the rare earth elements scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or mixtures thereof.

[0010] As used herein, “silica” refers to silicon oxide in the form of SiO2. Conversely, “elemental silicon” refers to silicon without alloying material, excluding accidental impurities. “Elemental silicon” is sometimes technically referred to as “metallic silicon.” Elemental silicon has a melting point of approximately 1414°C.

[0011] As used herein, “alumina” refers to aluminum oxide in the form of Al2O3.

[0012] As used herein, "mullite" generally refers to minerals containing alumina and silica (i.e., aluminum silicate). In other words, mullite is a compound of alumina and silica. Typically, mullite can have a ratio of approximately 3:2 alumina (Al2O3) to silica (SiO2) (e.g., within 10 mol% of a 3:2 alumina-silica ratio). However, a ratio of approximately 2:1 has also been reported as mullite (e.g., within 10 mol% of a 2:1 alumina-silica ratio).

[0013] As used herein, “boromlite” generally refers to minerals containing aluminum, boron, silicon, and oxides (i.e., aluminum silicate). In other words, boromlite is a compound of alumina, boron oxide, and silica. In embodiments, boromlite may have a chemical formula in which alumina and boron oxide are present in a ratio of 9:2 and within 10 mol%. For example, boromlite may be Al9BSi2O 19 To form a mixture of less than 10 mol%, the combination of Al2SiO5 and Al5BO9 may be less than 10 mol%.

[0014] As used herein, the term “borosilicate glass” generally refers to silica and boron trioxide as the main glass-forming components.

[0015] In this disclosure, when a layer is described as "in" or "on" another layer or substrate, unless otherwise expressly stated, the layers may either be in direct contact with each other or may have other layers or features between them. Therefore, these terms only describe the relative position of the layers to each other, and the relative position of above or below does not necessarily mean "on top of".

[0016] Embodiments of the present disclosure are referenced in detail here, and one or more examples of those embodiments are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar designations in the drawings and description are used to refer to the same or similar parts of the present disclosure.

[0017] Silicon carbide and silicon nitride ceramics undergo oxidation in dry, high-temperature environments. This oxidation generates a passive silicon oxide scale on the material's surface. In humid, high-temperature environments containing water vapor, such as turbine engines, both oxidation and pitting occur due to the formation of the passive silicon oxide scale and the subsequent conversion of silicon oxide to gaseous silicon hydroxide. To prevent pitting in humid, high-temperature environments, environmental barrier coatings (EBCs) are deposited on silicon carbide and silicon nitride materials.

[0018] Currently, EBC materials are made from rare-earth silicate compounds. These materials prevent depressions by sealing in water vapor and preventing it from reaching the silicon oxide scale on the silicon carbide or silicon nitride surface. However, such materials cannot prevent oxygen penetration, which consequently leads to oxidation of the underlying substrate. Oxidation of the substrate, along with the release of gaseous carbon or nitrogen oxides, produces a passive silicon oxide scale. Since gaseous carbon (i.e., CO, CO2) or nitrogen (i.e., NO, NO2, etc.) oxides cannot escape through dense EBCs, bulges can form, potentially leading to EBC fracture. The use of silicon bond coats has so far been a solution to this bulging problem. Silicon bond coats form a layer of thermally grown silica oxide (TGO) beneath the EBC without releasing gaseous byproducts.

[0019] However, pure silica has a strong tendency to devitrify or crystallize. Crystalline silica is prone to cracking due to phase transformation, and therefore threatens the mechanical integrity of EBC. Thus, an improved TGO layer is welcome in this technology.

[0020] A coated component having a bond coat formulated to form an improved TGO layer between the bond coat and the EBC is generally provided, along with a method for forming it. Generally, the bond coat comprises a silicon-based matrix and a reinforcing phase, the reinforcing phase forming a TGO layer containing dispersions of aluminum silicate crystals in a silicate oxide matrix during oxidation during use of the coated component. If we do not wish to be bound by specific reasoning, it is considered that aluminum silicate crystals (e.g., mullite materials) can form crystals in a silicate oxide matrix (e.g., borosilicate glass), which can help strengthen the TGO layer against creep. Thus, the resulting TGO layer can have greater creep strength while having stronger resistance to crystallization than pure silica. Therefore, the TGO layer in the EBC can remain amorphous for a longer period of time, effectively extending the lifespan of the EBC system. The TGO layer is generally formed from the constituent materials in the bond coat, as described in more detail below.

[0021] Referring to Figure 1, an example coated part 10 is shown, which includes a silicon-containing substrate 12 having a surface 14 on which the EBC system 15 is located. The EBC system 15 includes a bond coat 16 on the surface 14 of the silicon-containing substrate 12 and EBC 18 on the bond coat 16. Generally, the bond coat 16 is available between the substrate 12 and the EBC 18 to enhance the adhesion of the EBC 18 to the substrate 12, and potentially functions as a sacrificial oxide layer within the EBC system 15.

[0022] Generally, the bond coat 16 comprises a silicon-based matrix and a reinforcing phase dispersed in the silicon-based matrix. Referring to Figure 1, the bond coat 16 generally comprises a plurality of base phases, such as a silicon-based matrix 26 (e.g., boron-doped silicon or elemental silicon) and a reinforcing phase 28 (e.g., comprising aluminum silicate such as mullite, boromullite, or mixtures thereof). In embodiments, the bond coat may comprise from 75 wt% to 99.9 wt% of the silicon-based matrix 26 and from 0.1 wt% to 25 wt% of the reinforcing phase 28.

[0023] Each or both of the silicon-based matrix 26 and / or the reinforcing phase 28 comprises boron, such as in boron-doped silicon or boromullite, so that borosilicate glass can be formed in a subsequent TGO phase (Figure 2).

[0024] In one embodiment, the silicon-based matrix 26 comprises boron-doped silicon, and the reinforcing phase 28 comprises a mullite-based material (e.g., mullite). For example, the bond coat 16 may be at least 50 wt% boron-doped silicon as the silicon-based matrix 26 (e.g., from 50 wt% to 95 wt% boron-doped silicon). Such boron-doped silicon may comprise from 0.1 wt% to 10 wt% boron and from 90 wt% to 99.9 wt% silicon (i.e., elemental silicon), such as from 0.1 wt% to 5 wt% boron and from 95 wt% to 99.9 wt% silicon. Without wishing to be bound by any specific theory, it is contemplated that the oxide of such bond coat 16 forms the TGO layer 20 (Figure 2) comprising borosilicate glass from the oxide of boron-doped silicon. The mullite-based material in the bond coat 16 can form a portion of the TGO layer 20 as the TGO layer 20 grows and the bond coat 16 is consumed upon exposure to oxygen, and can undergo a solution reprecipitation process within the borosilicate glass. The mullite-based material can also react with the borosilicate glass and alter the composition of the borosilicate glass.

[0025] In another embodiment, the bond coat 16 may comprise a silicon-based matrix 26 comprising silicon (e.g., elemental silicon or boron-doped silicon), and a reinforcing phase 28 comprising boromullite. For example, the bond coat 16 may comprise at least 50 wt% silicon (e.g., from 50 wt% to 95 wt% silicon) as the silicon-based matrix 26. Because boron is present in the boromullite, the silicon in the bond coat 16 may be in the form of elemental silicon. Without wishing to be bound by any particular theory, it is contemplated that the oxide of such a bond coat 16 together forms a TGO layer 20 comprising borosilicate glass from the oxidation of silicon and boromullite together. The mullite-based material can migrate from the bond coat 16 to the TGO layer 20, where it crystallizes within the borosilicate glass.

[0026] Generally, mullite has a relatively slow diffusivity for oxygen at all temperatures of interest, up to 1650°C (e.g., from 1200°C to 1650°C). At temperatures above 1200°C, alumina is believed to be the only other oxide crystal that has a lower oxygen diffusivity than mullite; however, alumina has a much larger coefficient of thermal expansion compared to the substrate 12, and cannot be deposited as a dense, crack-free coating. Mullite has a coefficient of thermal expansion ("CTE") that is similar to the coefficient of thermal expansion of SiC-based CMC substrates and that of silicon (of the silicon-based matrix 26), although the CTE of mullite does not exactly match that of SiC or Si. For example, mullite has a CTE of about 5.5×10 -6 / K, and boromullite has a CTE of about 4.9×10 -6 / K. Because both mullite and boromullite have a good compatibility with silicon and CMC, they provide mechanical stability to the bond coat 16.

[0027] However, this slight CTE non-conformity can lead to thermal expansion-related problems, such as cracking and / or delamination, if the bond coat 16 is too thick. For example, a bond coat 16 with a thickness of 508 μm is likely to develop problems related to CTE non-conformity after repeated exposure to operating temperatures. On the other hand, a bond coat 16 with a maximum thickness of 381 μm or less, such as from 25.4 μm to 381 μm, can be well conformed to survive at such operating temperatures without significant problems due to CTE non-conformity. In one specific embodiment, the bond coat 16 has a maximum thickness of 254 μm, such as from 75 μm to 254 μm. In one specific embodiment, multiple phases of the bond coat 16 have substantially the same thickness. For example, a silicon-based phase may have a first thickness, and a mullite-based phase may have a second thickness, with the first thickness being within 5% of the second thickness.

[0028] Referring to Figure 2, the bond coat 16 comprises silicon and a constituent material configured to form a TGO layer 20 in oxidation of the bond coat 16, which includes a dispersion of aluminum silicate crystals (e.g., mullite material) in a silicate oxide matrix (e.g., borosilicate glass). The TGO layer 20 is generally formed on the bond coat 16 between the bond coat 16 and the EBC 18.

[0029] As stated, the TGO layer 20 comprises a silicate oxide matrix (e.g., borosilicate glass) and an aluminum silicate crystal (e.g., mullite material). Silica may be present in the TGO layer 20, which can be formed in the oxidation of silicon in the bond coat 16. If we do not wish to be bound by specific reasoning, the dispersion of aluminum silicate crystal (e.g., mullite material) is present in an amount sufficient to substantially stabilize the amorphous structure of the TGO layer 20, specifically the amorphous structure of the silicate oxide matrix (e.g., borosilicate glass) in the TGO layer 20. Thus, the TGO layer 20 is more resistant to creep at higher temperatures than a borosilicate glass TGO layer that does not contain dispersion of aluminum silicate crystal (e.g., mullite material). By leaving amorphous, the silicate oxide matrix (e.g., borosilicate glass) in the TGO layer 20 helps to avoid cracking during thermal cycling. If we do not wish to be bound by specific reasoning, the TGO layer 20, if crystalline, will take the form of cristobalite, which undergoes a reversible phase transformation at approximately 270°C. This phase transformation may involve a volume change that can lead to cracking of the TGO layer 20.

[0030] In one embodiment, the TGO layer 20 contains 75 wt% to 99.9 wt% of a silicate oxide matrix (e.g., borosilicate glass). In another embodiment, the TGO layer 20 contains 0.1 wt% to 25 wt% of aluminum silicate crystals (e.g., mullite material). If we do not wish to be bound by specific reasoning, it is conceivable that excess aluminum silicate crystals in the TGO layer 20 may lead to phase separation, since the silicate oxide matrix remains amorphous while the aluminum silicate crystals can form a dense phase of crystallized mullite.

[0031] In general, aluminum silicate crystals provide mechanical stability within the TGO layer 20. Referring to Figure 2, the TGO layer 20 shows aluminum silicate crystals 22 dispersed within a silicate oxide matrix 24. In embodiments, at least a portion of the aluminum silicate crystals 22 spreads across the TGO layer 20. Thereafter, the portion of the aluminum silicate crystals 22 spreading across the TGO layer 20 can interact with the bond coat 16 and the EBC 18 to provide mechanical stability between them (for example, they can be bonded). In embodiments, at least a portion of the aluminum silicate crystals 22 are entangled with each other within the TGO layer 20. Thus, the aluminum silicate crystals 22 can form an entangled network structure spreading across the TGO layer 20, providing mechanical connectivity between the bond coat 16 and the EBC 18.

[0032] In the embodiment, the aluminum silicate crystal 22 can be inherently elongated, such as having an aspect ratio greater than 5. For example, the aluminum silicate crystal 22 may have an aspect ratio ranging from 10 to 1000.

[0033] The aluminum silicate crystals 22 may include mullite materials such as mullite, boromullite, or both (e.g., mixtures thereof). The specific composition of the mullite material in the aluminum silicate crystals 22 within the TGO layer 20 may be controlled based on the composition of the bond coat 16, which forms the TGO layer 20 during oxidation between uses of the coated component. In other words, the bond coat 16, upon exposure of the coated component to an oxidizing environment, causes the TGO to migrate and oxidize, resulting in the formation of borosilicate glass in situ from the constituent materials of the bond coat 16 and the migration of the mullite material from the bond coat 16.

[0034] In embodiments, the substrate 12 in Figures 1 and 2 is formed from a silicon-containing material such as a ceramic matrix composite ("CMC") material. As used herein, ceramic matrix composite or "CMC" refers to a material in the field that includes a reinforcing material (e.g., reinforcing fibers) surrounded by a ceramic matrix phase. Generally, the reinforcing fibers provide structural integrity to the ceramic matrix. Some examples of matrix materials for CMCs, but not limited to, may be non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates, or mixtures thereof), or mixtures thereof. Optionally, ceramic particles (e.g., oxides of Si, Al, Zr, Y, and combinations thereof) and inorganic fillers (e.g., pyrophyllite, wollastonite, mica, talc, kyanite, montmorillonite) may be included in the CMC matrix.

[0035] Some examples of CMC reinforcing fibers may include, but are not limited to, non-oxide silicon-based materials (e.g., silicon carbide, silicon nitride, or mixtures thereof), non-oxide carbon-based materials (e.g., carbon), oxide ceramics (e.g., silicon oxycarbide, silicon oxynitride, aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates such as mullite, or mixtures thereof), or mixtures thereof.

[0036] In general, specific CMCs can be referred to as combinations of fiber types / matrix types. For example, C / SiC represents carbon fiber reinforced silicon carbide, SiC / SiC represents silicon carbide fiber reinforced silicon carbide, SiC / SiN represents silicon carbide fiber reinforced silicon nitride, and SiC / SiC-SiN represents a silicon carbide fiber reinforced silicon carbide / silicon nitride matrix mixture, and so on. In other examples, a CMC may consist of a matrix and reinforcing fibers containing aluminum oxide (Al2O3), silicon dioxide (SiO2), aluminosilicates, and mixtures thereof. Aluminosilicates may include crystalline materials such as mullite (3Al2O32SiO2) and glassy aluminosilicates.

[0037] In certain embodiments, the reinforcing fibers may be bundled and / or coated before being incorporated into the matrix. For example, the fiber bundles may be formed as reinforcing tapes, such as unidirectional reinforcing tapes. Multiple tapes may be laid together to form a preform part. The fiber bundles may be impregnated with a slurry composition before or after the formation of the preform. The preform can then undergo heat treatment, such as curing or burning, to produce a high char residue in the preform, and subsequent chemical treatment, such as silicon dissolution infiltration, to arrive at a part formed from a CMC material having the desired chemical composition.

[0038] Such materials, along with certain monolithic ceramics (i.e., ceramic materials without reinforcing materials), are particularly well-suited for higher-temperature applications. Furthermore, these ceramic materials are lighter than superalloys, yet can still provide strength and durability to components made from superalloys. Therefore, such materials are currently being considered for many gas turbine components used in the higher-temperature regions of gas turbine engines, such as airfoil sections (e.g., turbine blades), combustors, shrouds, and other similar components, where the lighter weight and higher temperature capabilities they can offer would be beneficial.

[0039] As previously stated, the bond coat 16 and the TGO layer 20 can be used in conjunction with the EBC 18 to form a coated component 10 with an improved effective service life for the EBC system 15. As used herein, the environmental shielding coating or "EBC" refers to a coating comprising one or more layers of ceramic material, each providing specific or multifunctional protection to the underlying CMC. EBC generally comprises multiple layers, including rare earth silicate coatings (e.g., rare earth disilicates such as slurry or air plasma spray-deposited ("APS-deposited") yttrium ytterbium disilicate (YbYDS)), alkaline earth aluminosilicates (e.g., barium-strontium-aluminum silicate (BSAS), having a composition range of BaO, SrO, Al2O3, SiO2, or combinations thereof), a sealing layer (e.g., rare earth disilicate), and an outer coating (e.g., rare earth monosilicates such as slurry or APS-deposited yttrium monosilicate (YMS), or combinations thereof). One or more layers may be doped as desired, and EBC18 may be covered with an abrasive coating.

[0040] EBC18 may comprise one or any combination of one or more layers formed from materials selected from the chemical composition of a typical EBC18 or thermal barrier coating ("TBC") layer, including but not limited to rare earth silicates (e.g., monosilicates and disilicates), aluminosilicates (e.g., mullite, barium strontium aluminosilicate (BSAS), rare earth aluminosilicates, etc.), hafnia, zirconia, stabilized hafnia, stabilized zirconia, rare earth hafnate, rare earth zirconate, rare earth gallium oxide, etc. EBC18 may comprise a hafnia layer, an alumina layer, or both. Alternatively or additionally, EBC18 may comprise a rare earth disilicate layer, a rare earth monosilicate layer, or both. EBC18 may be formed from a plurality of separate layers 19. In the embodiments shown, EBC18 may comprise a sealing layer, a silicate layer, or any combination of any of the above layers.

[0041] The coating component 10 is particularly suitable for use as a component found in high-temperature environments, such as those present in gas turbine engines, including combustor components, turbine blades, shrouds, nozzles, heat shields, and blades. Specifically, the coating component 10 may be a CMC component positioned in a high-temperature gas flow path such that when exposed to the high-temperature gas flow path of a gas turbine, the underlying substrate 12 is protected by the EBC system forming an environmental barrier to protect components within the gas turbine. Specifically, the coating component 10 may be particularly suitable for rotating parts that are subjected to long-term use under strong centrifugal forces.

[0042] Methods for forming coated parts, such as any of the coated parts in the examples above, are also generally provided. Referring to Figure 3, an example method 30 for forming coated parts, such as those described above, is shown. In reference numeral 32, a bond coat is formed on the surface of a substrate (e.g., a silicon-containing substrate), the bond coat comprising a silicon-based matrix in which a reinforcing phase is dispersed. In reference numeral 34, an EBC is formed in the bond coat. In reference numeral 36, the coated part is optionally exposed to an oxidizing environment such that a TGO layer is formed in the bond coat between the bond coat and the environmental shielding coating.

[0043] Further aspects are provided by the subject matter of the following clauses.

[0044] A coated component comprising a silicon-containing substrate having a surface, a bond coat on the surface of the silicon-containing substrate comprising a silicon-based matrix in which a reinforcing phase is dispersed, and an environmental shielding coating on the bond coat.

[0045] The reinforcing phase is a coating component containing aluminum silicate, as in any prior clause.

[0046] Aluminum silicate is a coating component, including mullite or boromullite, as described in any prior clause.

[0047] The bond coat silicon is boron-doped silicon, as in any prior clause for coating components.

[0048] The bond coat is a coating component as described in any prior clause, containing boron-doped silicon ranging from 50 wt% to 95 wt%.

[0049] Boron-doped silicon is a coating component, as described in any prior clause, comprising 0.1 wt% to 10 wt% boron and 90 wt% to 99.9 wt% silicon.

[0050] The reinforcing phase includes mullite and other covering components as described in any prior clause.

[0051] Bond coat is a coating component containing elemental silicon, as described in any prior clause.

[0052] The reinforcing phase includes coating components such as boromlite, as in any prior clause.

[0053] Boromlite is a coating component having a chemical formula of 9:2 alumina and boron oxide in an amount of 10 mol% or less, as described in any prior clause.

[0054] The bond coat is a coating component as described in any prior clause, containing 0.1 wt% to 25 wt% boromlite.

[0055] A coating component as in any prior clause, comprising a thermally grown oxide layer positioned between a bond coat and an environmental shielding coating, further comprising a thermally grown oxide layer containing dispersions of aluminum silicate crystals within a silicate oxide matrix.

[0056] The thermally grown oxide is a coating component as described in any preceding clause, comprising a dispersion of 0.1 wt% to 25 wt% aluminum silicate crystals and a silicate oxide matrix of 75 wt% to 99.9 wt%.

[0057] Aluminum silicate crystals include mullite materials, such as coating components as described in any preceding clause.

[0058] The silicate oxide matrix includes borosilicate glass, as in any of the preceding clauses, for coating components.

[0059] A coating component, as in any preceding clause, wherein at least a portion of the silicate aluminum-based crystals extends into a thermally grown oxide layer.

[0060] Aluminum silicate crystals intertwine within a thermally grown oxide layer, forming a coating component as described in any preceding clause.

[0061] Aluminum silicate crystals are coating components, such as those in any preceding clause, having an aspect ratio greater than 5.

[0062] The base material is a ceramic matrix composite, as in any preceding clause, for the covering component.

[0063] A gas turbine engine comprising a covering component as described in any of the preceding provisions, wherein the environmental shielding coating of the covering component is exposed to a high-temperature gas path within the gas turbine engine.

[0064] A method for forming a covering component as described in any preceding clause.

[0065] A method for forming a coated component, comprising the steps of: forming a bond coat on the surface of a silicon-containing substrate, wherein the bond coat comprises a silicon-based matrix in which a reinforcing phase is dispersed; and forming an environmental shielding coating on the bond coat, wherein, upon subsequent exposure of the coated component to an oxidizing environment, a thermally grown oxide layer is formed on the bond coat between the bond coat and the environmental shielding coating, and the thermally grown oxide layer comprises a dispersion of silicate aluminum crystals in a silicate oxide matrix.

[0066] The descriptions in this document, including the best mode, are provided with examples to enable a person skilled in the art to implement the disclosure, including by making and using any device or system and by implementing any incorporated method. The patentable scope of the disclosure is defined by the claims and may include other examples that a person skilled in the art can conceive of. Such other examples are intended to be within the scope of the claims if they include structural elements that are not different from the literal wording of the claims, or equivalent structural elements that are substantially different from the literal wording of the claims.

[0067] Further aspects of the present invention are provided by the subject matter of the following clauses.

[0068] 1. A silicon-containing substrate (12) having a surface (14), A bond coat (16) on the surface (14) of a silicon-containing substrate (12), comprising a silicon-based matrix (26) in which a reinforcing phase (28) is dispersed, Environmental shielding coating (18) in Bond Coat (16) and Covering component (10) including.

[0069] 2. The reinforcing phase (28) comprises aluminum silicate, as specified in any preceding clause.

[0070] 3. Aluminum silicate, including mullite or boromlite, is not permitted for any of the preceding clauses.

[0071] 4. The silicon of the bond coat (16) is boron-doped silicon, as specified in any of the preceding clauses for the coating parts.

[0072] 5. The bond coat (16) contains boron-doped silicon ranging from 50 wt% to 95 wt%, as per any prior clause.

[0073] 6. Boron-doped silicon is any coating component of the preceding clause, comprising 0.1 wt% to 10 wt% boron and 90 wt% to 99.9 wt% silicon.

[0074] 7. The reinforcing phase (26) includes any of the preceding clauses' covering components, including mullite.

[0075] 8. The bond coat (16) is a coating component of any of the preceding clauses, containing elemental silicon.

[0076] 9. Reinforcement phase (26) includes any of the preceding clauses' covering components, including boromlite.

[0077] 10. Boromlite has a chemical formula of 9:2 alumina and boron oxide in an amount of 10 mol% or less, and the bond coat (16) contains 0.1 wt% to 25 wt% of the boromlite, as per any prior clause coating component.

[0078] 11. A coated component of any of the preceding clauses, comprising a thermally grown oxide layer (20) positioned between a bond coat (16) and an environmental shielding coating, further comprising a thermally grown oxide layer (20) containing dispersions of aluminum silicate crystals within a silicate oxide matrix.

[0079] 12. The thermally grown oxide (20) comprises a dispersion of 0.1 wt% to 25 wt% aluminum silicate crystals and a silicate oxide matrix of 75 wt% to 99.9 wt% for any of the preceding clauses of the coating component.

[0080] 13. The substrate is a ceramic matrix composite, the silicate aluminum-based crystals contain mullite-based material, and the silicate oxide matrix contains borosilicate glass, as per any of the preceding clauses.

[0081] 14. A coating component of any of the preceding clauses, wherein at least a portion of the aluminum silicate crystals extends into a thermally grown oxide layer (20), and the aluminum silicate crystals are intertwined within the thermally grown oxide layer (20).

[0082] 15. A method for forming a coated component, A step of forming a bond coat (16) on the surface of a silicon-containing substrate, wherein the bond coat (16) includes a silicon-based matrix in which a reinforcing phase (26) is dispersed, The step of forming an environmental shielding coating (18) on a bond coat (16), wherein, upon subsequent exposure of the coated component to an oxidizing environment, a thermally grown oxide layer (20) is formed on the bond coat (16) between the bond coat (16) and the environmental shielding coating (18), and the thermally grown oxide layer (20) comprises a dispersion of silicate aluminum crystals in a silicate oxide matrix, and A method that includes this. [Explanation of symbols]

[0083] 10 Covering parts 12 Silicon-containing substrate 14 Surface 15 EBC System 16 Bond Coat 18 EBC 20 TGO layers 22. Aluminum silicate crystals 24 Silicate Oxide Matrix 26 Silicon-based matrices 28 Strengthening phase

Claims

1. A silicon-containing substrate (12) having a surface (14), A bond coat (16) on the surface (14) of the silicon-containing substrate (12), comprising a silicon-based matrix (26) in which a reinforcing phase (28) is dispersed, The environmental shielding coating (18) in the bond coat (16) and Covering component (10) including.

2. The coating component according to claim 1, wherein the reinforcing phase (28) comprises aluminum silicate.

3. The coating component according to claim 2, wherein the aluminum silicate comprises mullite or boromlite.

4. The coated part according to claim 1, wherein the silicon of the bond coat (16) is boron-doped silicon.

5. The coated part according to claim 4, wherein the bond coat (16) contains 50 wt% to 95 wt% of the boron-doped silicon.

6. The coating component according to claim 4, wherein the boron-doped silicon comprises 0.1 wt% to 10 wt% boron and 90 wt% to 99.9 wt% silicon.

7. The coating component according to claim 4, wherein the reinforcing phase (26) includes mullite.

8. The coated component according to claim 1, wherein the bond coat (16) contains elemental silicon.

9. The coating component according to claim 8, wherein the reinforcing phase (26) includes boromlite.

10. The coating component according to claim 9, wherein the boromlite has a chemical formula in which alumina and boron oxide are in a ratio of 9:2 and within 10 mol%, and the bond coat (16) contains 0.1 wt% to 25 wt% of the boromlite.

11. The coated component according to claim 1, further comprising a thermally grown oxide layer (20) positioned between the bond coat (16) and the environmental shielding coating, the thermally grown oxide layer (20) containing dispersions of aluminum silicate crystals within a silicate oxide matrix.

12. The coated component according to claim 11, wherein the thermally grown oxide (20) comprises a dispersion of the aluminum silicate crystals in an amount of 0.1 wt% to 25 wt% and the silicate oxide matrix in an amount of 75 wt% to 99.9 wt%.

13. The coating component according to claim 11, wherein the substrate is a ceramic matrix composite, the silicate aluminum crystals include a mullite material, and the silicate oxide matrix includes borosilicate glass.

14. The coated component according to claim 11, wherein at least a portion of the aluminum silicate crystals spreads into the thermally grown oxide layer (20), and the aluminum silicate crystals are intertwined within the thermally grown oxide layer (20).

15. A method for forming a coated component, A step of forming a bond coat (16) on the surface of a silicon-containing substrate, wherein the bond coat (16) includes a silicon-based matrix in which a reinforcing phase (26) is dispersed, The step of forming an environmental shielding coating (18) on the bond coat (16), wherein, upon subsequent exposure of the coated component to an oxidizing environment, a thermally grown oxide layer (20) is formed on the bond coat (16) between the bond coat (16) and the environmental shielding coating (18), and the thermally grown oxide layer (20) comprises a dispersion of silicate aluminum crystals in a silicate oxide matrix. A method that includes this.

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