Environmentally resistant materials and coatings containing a low melting temperature phase

Abstract

Environmentally resistant materials and coatings containing low melting temperature materials are provided. The materials and coatings include high melting temperature materials such as rare earth silicates, mullite, hafnium, zircon, HfO2, and rare earth stabilized ZrO2. The low melting temperature materials have melting temperatures below 1500°C. The low melting temperature materials in the coating melt in situ, flow, and fill microstructural defects after post heat treatment. Due to the reduced microstructural defects, the EBC containing the low melting temperature materials provides enhanced blocking to oxidant diffusion, resulting in a 10 times slower TGO growth rate compared to coatings without the low melting temperature materials.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 63 / 329,575, filed April 11, 2022, the disclosure of which is expressly incorporated herein by reference in its entirety.

[0002] FIELD OF THEINVENTION The present disclosure relates to an Environmental Barrier Coating (EBC) on a Si-based Ceramic Matrix Composite (CMC) that can protect the CMC in high temperature oxidizing environments. In an exemplary embodiment, a thermal spray material feedstock containing a low melting temperature material melts, diffuses, and fills in-situ EBC microstructural defects during high temperature coating conditions. Due to the reduction of microstructural defects, the EBC containing the low melting temperature material provides enhanced barrier against oxidant (water vapor and oxygen) diffusion and slows the growth rate of Thermally Grown Oxide (TGO) by more than two times compared to coatings without the low temperature material. For example, in some preferred embodiments, the TGO growth rate is five times (or more) slower for EBC coatings containing low melting temperature materials compared to EBC coatings without the low melting temperature materials. In even more preferred embodiments, the TGO growth rate is ten times (or more) slower for EBC coatings containing low melting temperature materials compared to EBC coatings without the low melting temperature materials. [Background technology]

[0003] Rare earth silicates and mullite have traditionally been used in environmental barrier coatings (EBCs) applied to Si-based ceramic matrix composites to protect CMCs from oxidation and water vapor attack. Conventional EBCs contain a Si bond coat and an ytterbium silicate top coat. Air Plasma Spray (APS) is a process traditionally used for EBC deposition. However, the coating after the APS process typically contains at least some porosity, as well as microstructural defects such as splat boundaries and microcracks. In the high-temperature gas turbine engine environment, these microstructural defects provide fast diffusion paths for oxidants (water vapor and oxygen) to reach the Si bond coat and accelerate the Si bond coat oxidation. When exposed to the high-temperature oxidizing environment in the gas turbine engine, the Si bond coat also oxidizes to form a thermally grown oxide (TGO) SiO2 layer. When the TGO layer reaches a threshold thickness, the EBC spalls. Therefore, there is a need for a new dense, crack-free EBC to protect the Si bond coat and CMC substrate from oxidation, reduce the TGO growth rate, and improve coating durability. Summary of the Invention

[0004] An objective of the present disclosure is to obtain a dense, crack-free EBC that can prevent oxidants (water vapor and oxygen) from reaching the underlying components (e.g., silicon bond coat and / or CMC substrate). In some embodiments, such an EBC can be obtained from a thermal spray material feedstock that includes a first powder that includes at least one low melting temperature material having a melting temperature below 1500° C. and a second powder that includes at least one environmental coating matrix material (typically a high melting temperature matrix material).

[0005] In some embodiments, the at least one low melting temperature material is a mono-oxide compound, a binary oxide, a ternary oxide, or a complex oxide. For example, in some embodiments, the low melting temperature material may include at least four oxides having a melting temperature of less than 1300° C.

[0006] In some embodiments, the at least one environmental barrier coating matrix material (which is typically a high melting temperature matrix material) comprises at least one material selected from the group consisting of rare earth silicates, rare earth oxides, mullite, alkali silicates, HfO2, HfSiO4, HfTiO4, ZrTiO4, ZrSiO4, rare earth oxide stabilized zirconia, rare earth oxide stabilized hafnia, HfB2, HfC, ZrB2, ZrC, and SiC.

[0007] In some embodiments, the first powder and the second powder are blended, agglomerated, agglomerated and sintered, plasma densified, or melted and milled.

[0008] In some particular embodiments, the at least one low melting temperature material comprises CaO, MgO, Al2O3, SiO2, Na2O, K2O, and Fe2O3. In other embodiments, the at least one low melting temperature material is Li2O.

[0009] In some embodiments, the EBC may include an EBC top coat comprising an EBC matrix (which is generally a high melting temperature matrix material) comprising a material selected from the group consisting of rare earth silicate, rare earth oxide, mullite, alkali silicate, HfO2, HfSiO4, HfTiO4, ZrTiO4, ZrSiO4, rare earth oxide stabilized zirconia, rare earth oxide stabilized hafnia, HfB2, HfC, ZrB2, ZrC, SiC, and combinations thereof, and at least one low melting temperature material having a melting temperature less than 1500° C. embedded in the EBC matrix, and a Si-based bond coat.

[0010] In some embodiments, the at least one low melting temperature material of the EBC may include CaO, MgO, Al2O3, SiO2, Na2O, K2O, and Fe2O3. In other embodiments, the at least one low melting temperature material of the EBC is Li2O.

[0011] In some embodiments, the EBC matrix comprises at least one rare earth silicate comprising at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. In other embodiments, the EBC matrix comprises at least one rare earth oxide comprising at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. [Brief description of the drawings]

[0012] The present disclosure will be further explained in the following detailed description with reference to the several drawings mentioned as non-limiting examples of preferred embodiments of the present disclosure. [Figure 1] FIG. 2 is a schematic diagram of the as-deposited coating microstructure. [Figure 2A] FIG. 2 is a schematic diagram of a powder mix including a matrix powder and a low melting temperature powder. [Figure 2B] FIG. 2 is a schematic diagram of an agglomerated powder comprising a matrix powder and a low melting temperature powder. [Diagram 3] 1 shows a Scanning Electron Microscope (SEM) image of the high melting temperature matrix powder and the first low melting temperature powder. [Figure 4A] FIG. 13 is an SEM image of an as-sprayed APS Yb2Si2O7 coating showing microcracks and splat boundaries. [Figure 4B] FIG. 13 is an SEM image of a heat-treated APS Yb2Si2O7 coating showing microcracks and splat boundaries. [Figure 4C]FIG. 13 is an SEM image of the as-sprayed APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating. [Figure 4D] FIG. 13 is an SEM image of the heat treated APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating. [Figure 5A] FIG. 13 shows SEM images of Yb2Si2O7 coatings evaluated at 1316 °C in 90 vol.% H2O-10 vol.% air after 170 h exposure time. [Figure 5B] FIG. 13 shows SEM images of Yb2Si2O7 coatings evaluated at 1316 °C in 90 vol.% H2O-10 vol.% air after 510 h exposure time. [Figure 5C] FIG. 13 is a SEM image of the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating evaluated at 1316 °C in 90 vol.% H2O-10 vol.% air after 170 h exposure time. [Figure 5D] FIG. 13 is a SEM image of the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating evaluated at 1316 °C in 90 vol.% H2O-10 vol.% air after 510 h exposure time. [Figure 6] 1 is a graph showing TGO thickness as a function of exposure for Yb2Si2O7 coatings and APS Yb2Si2O7-sodium calcium magnesium aluminate silicate coatings. [Figure 7] FIG. 2 is an SEM image of a high melting temperature matrix powder and a second low melting temperature powder. [Figure 8A] FIG. 13 is a SEM image of the as-sprayed APS Yb2Si2O7-0.4 wt% Li2O coating. [Figure 8B] FIG. 13 is a SEM image of heat-treated APS Yb2Si2O7-0.4 wt% Li2O coating. [Figure 9A]FIG. 13 shows SEM images of Yb2Si2O7 coatings evaluated at 1316 °C in 90 vol.% H2O-10 vol.% air after 410 h exposure time. [Figure 9B] FIG. 13 shows SEM images of Yb2Si2O7-0.4 wt% Li2O coating evaluated in 90 vol% H2O-10 vol% air at 1316 °C after 410 h exposure time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In the following description, various embodiments of the present disclosure will be described with reference to the accompanying drawings. Where necessary, detailed embodiments of the present disclosure will be described herein. However, it should be understood that the disclosed embodiments are merely exemplary of embodiments of the present disclosure that may be embodied in various alternative forms. The figures are not necessarily to scale, and some features may be exaggerated or minimized to show details of specific components. Therefore, specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to employ the present disclosure in various ways.

[0014] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly indicates otherwise. For example, reference to "a powder material" also means that a mixture of one or more powder materials may be present, unless specifically excluded. As used herein, the indefinite article "a" indicates one as well as more than one and does not necessarily limit its referent noun to the singular form.

[0015] Unless otherwise indicated, all numbers expressing quantities used in the specification and claims should be understood to be modified in all examples by the term "about". Thus, unless otherwise indicated, the numerical parameters set forth in the specification and claims are approximations that may vary depending on the desired properties sought to be obtained by the embodiments of the present disclosure. At the very least, they should not be considered as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, and each numerical parameter should be construed in light of the number of significant digits and ordinary rounding techniques.

[0016] It should be noted that the recitation of numerical ranges within this specification is considered to be a disclosure of all numerical values ​​and ranges within that range (unless expressly indicated otherwise). For example, if a range is from about 1 to about 40, it is considered to include, for example, 1, 7, 23.7, 34, 36.1, 40, or any other value or range within that range.

[0017] As used herein, the terms "about" and "approximately" indicate that the amount or value in question may be the specified particular value or some other value in its vicinity. In general, the terms "about" and "approximately" referring to a particular value are intended to indicate a range within ±5% of that value. As an example, the phrase "about 100" indicates a range of 100 ±5, i.e., a range of 95 to 105. In general, when the terms "about" and "approximately" are used, it can be expected that similar results or effects according to the present disclosure can be obtained within a range of ±5% of the indicated value.

[0018] The term "at least partially" is intended to indicate that the following characteristic is met to some extent (eg, 25% or 50%) or completely.

[0019] The terms "substantially" and "essentially" are used to indicate that a following feature, characteristic or parameter is either completely (wholly) realized or satisfied, or to a major degree (e.g., 90%, 95%, or 99%) that has no adverse effect on the intended results.

[0020] The term "comprising" as used herein is intended to be non-exclusive and open-ended. Thus, for example, a composition comprising oxide A may contain other oxides other than A. However, the term "comprising" also includes the more restrictive meanings of "consisting essentially of" and "consisting of", so that, for example, "a composition comprising oxide A" may also consist (essentially) of oxide A.

[0021] In this disclosure, unless otherwise specified, all weight percentages relating to elements / components of a composition / material / layer are based on the total weight of the composition / material / layer including any unavoidable impurities that may be present.

[0022] The present disclosure relates to EBCs (e.g., EBCs including an EBC topcoat and a Si-based bond coat), as well as methods of applying the EBC to a substrate (and articles formed by applying the EBC to a substrate), such as a substrate selected from a Si-based ceramic matrix composite (CMC). In embodiments, the EBC coating compositions and structural configurations of the EBCs of the present disclosure can achieve excellent environmental coating bond coat adhesion, oxidation and fatigue resistance, and environmental protection performance, along with self-repair capabilities that can ensure long-term durability of the CMC.

[0023] In embodiments, the EBCs of the present disclosure may be made of any of a variety of materials, including rare earth silicates (comprising one or more rare earth elements selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), rare earth oxides (comprising one or more rare earth elements selected from Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), mullite (3Al2O3-2SiO2), alkali silicates, HfO2, HfSiO4, HfT and at least one low melting temperature material having a melting temperature of less than 1500°C embedded in the environmental barrier coating matrix (high melting temperature matrix material).

[0024] In some embodiments, at least one low melting temperature material having a melting temperature of less than 1500° C. may be embedded in the environmental barrier coating matrix (high melting temperature matrix material) in an amount ranging from 0.1% to 10% by weight (based on the total weight of the at least one low melting temperature material and the environmental barrier coating matrix (high melting temperature matrix material)), preferably in an amount ranging from 0.1% to 5% by weight, and more specifically in an amount ranging from 0.3% to 4% by weight.

[0025] 1, in some embodiments, the EBC 110 may be comprised of multiple layers directly adjacent to the substrate 100 (e.g., a SiC / SiC ceramic matrix composite substrate, etc.), which may provide enhanced environmental protection. In such embodiments, the EBC 110 may include a Si-based bond coat 120 and an EBC top coat 130.

[0026] If present, the Si-based bond coat 120 may have any desired coating thickness or range of coating thicknesses, such as, for example, a coating thickness ranging from 5 μm to 200 μm. In embodiments, the Si-based bond coat may include a Si-based metal. In some embodiments, the Si-based bond coat may be made from one or more of the following: MoSi2 or HfSi2, or Si-Al2O3, Si-Al2O3-RE2O3, where RE is a rare earth element.

[0027] The EBC topcoat 130 may have any desired coating thickness or range of coating thicknesses, such as, for example, a coating thickness ranging from 50 μm to 1000 μm. In an embodiment, the EBC topcoat layer 130 may include a high melting temperature matrix material 132 and a low melting temperature material 134 embedded within the high melting temperature matrix material 132. FIG. 1 also shows, generally, microcracks 136 that may occur throughout the EBC topcoat layer 130.

[0028] In some embodiments, the low melting temperature material is at least one oxide compound shown in Table 1 (below) (i.e., each powder particle or phase is made up of a single oxide compound). [Table 1]

[0029] In another embodiment, the low melting temperature material is at least one binary oxide as shown in Table 2 (below). [Table 2]

[0030] In yet another embodiment, the low melting temperature material is at least one ternary oxide as shown in Table 3 (below). [Table 3]

[0031] In yet another embodiment, the low melting temperature material is at least one double oxide mixture as shown in Table 4 (below). [Table 4]

[0032] In some embodiments, the low melting temperature material may be formed from a Calcium-Magnesium-Alumina-Silicate (CMAS) powder (having a melting temperature less than 1500° C.), such as a CMAS powder that includes 29% to 39% quartz (SiO), 25% to 35% gypsum (CaSOx2H0), 12% to 23% aplite (SiO+KALSiO), 9% to 19% dolomite (CaMg(Co)), and 3% to 7% salt (NaCl) by weight.

[0033] In other embodiments, the low melting temperature material may be formed from a CMAS powder (having a melting temperature less than 1500° C.), where the CMAS powder is selected from one of the following compositions: Composition 1: 60.0 mol% to 70.0 mol% SiO2, 15.0 mol% to 31.0 mol% CaO, 6.0 mol% to 10.0 mol% MgO, 2.0 mol% to 5.0 mol% Al2O3, 0.5 mol% to 5.0 mol% Na2O, and 0.1 mol% to 1.0 mol% K2O.

[0034] Composition 2: 50.0 mol% to 65.0 mol% SiO2, 25.0 mol% to 40.0 mol% CaO, 1.0 mol% to 6.0 mol% MgO, 1.0 mol% to 3.5 mol% Al2O3, 3.0 mol% to 5.0 mol% Na2O, and 0.01 mol% to 0.5 mol% K2O.

[0035] Composition 3: 25.0 mol% to 55.0 mol% SiO2, 35.0 mol% to 60.0 mol% CaO, 0.5 mol% to 5.0 mol% MgO, 0.5 mol% to 3.0 mol% Al2O3, 1.0 mol% to 5.0 mol% Na2O, and 0.0 mol% to 0.2 mol% K2O.

[0036] In some embodiments, the high melting temperature matrix material is comprised of rare earth silicates (including rare earth elements Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), rare earth oxides (including rare earth elements Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), mullite (3Al2O3-2SiO2), alkali silicates (BaO-SrO-Al2O3-SiO2), HfO2, HfSiO4, HfTiO4, ZrTiO4, ZrSiO4, rare earth oxide stabilized zirconia, rare earth oxide stabilized hafnia, HfB2, HfC, ZrB2, ZrC, SiC, and combinations thereof. In some embodiments, the material of the high melting temperature matrix may be selected such that the matrix has a melting temperature at least 350° C. higher than the melting temperature of the low melting temperature material. In some embodiments, a matrix formed from a high melting temperature matrix material may have a melting temperature in the range of 1800° C. to 3900° C., specifically in the range of 2200° C. to 3400° C., more specifically in the range of 2500° C. to 3000° C.

[0037] In some embodiments, the EBCs of the present disclosure may be formed from a thermal spray material feedstock that includes: (i) a first powder that includes a low melting temperature material having a melting temperature less than 1500° C.; and (ii) a second powder that includes a high melting temperature matrix material.

[0038] FIG. 2A shows a schematic diagram of an exemplary embodiment of a thermal spray material feedstock comprising a mixed powder including a high melting temperature matrix material powder 220 and a low melting temperature material powder 230 .

[0039] In some embodiments, the particle size distribution (in terms of particle size) of the high melting temperature matrix material powder may be in the range of 11 μm to 200 μm. In preferred embodiments, the particle size distribution of the high melting temperature matrix material powder may be in the range of 11 μm to 150 μm. In more preferred embodiments, the particle size distribution of the high melting temperature matrix material powder may be in the range of 11 μm to 125 μm.

[0040] In some embodiments, the high melting temperature matrix material powder may have an average size (diameter) in the range of 25 μm to 125 μm, preferably in the range of 25 μm to 90 μm.

[0041] In some embodiments, the particle size distribution (in terms of particle diameter) of the low melting temperature material powder may be in the range of 1 μm to 125 μm. In preferred embodiments, the particle size distribution of the low melting temperature material powder may be in the range of 2.5 μm to 75 μm, such as 5 μm to 62 μm. In more preferred embodiments, the particle size distribution of the low melting temperature material powder may be in the range of 5 μm to 55 μm.

[0042] In some embodiments, the low melting temperature material powder may have an average size (diameter) in the range of 5 μm to 40 μm, preferably in the range of 5 μm to 25 μm.

[0043] In some embodiments, the low melting temperature material powder has an average size smaller than the average size (diameter) of the high melting temperature matrix material powder (e.g., an average size at least 30% smaller (preferably at least 50% smaller) than the average size of the high melting temperature matrix material powder).

[0044] In some embodiments, the EBCs of the present disclosure may be formed from a thermal spray material feedstock that includes an agglomerated powder. Figure 2B is a schematic diagram of an exemplary embodiment of a thermal spray material feedstock that includes agglomerated powder particles that include a high melting temperature matrix material powder 220 and a low melting temperature material powder 230.

[0045] In some embodiments, the particle size distribution of the agglomerated powder may be in the range of 11 μm to 125 μm. In preferred embodiments, the particle size distribution of the agglomerated powder may be in the range of 11 μm to 90 μm. In more preferred embodiments, the particle size distribution of the agglomerated powder may be in the range of 11 μm to 62 μm.

[0046] In some embodiments, the high melting temperature matrix material powder and the low melting temperature material powder in the thermal spray material feedstock are produced by one or more of the following methodologies: blending, agglomerating, agglomerating and sintering, plasma densifying, or melting and grinding.

[0047] In embodiments, the Si-based bond coat and EBC top coat on the Si-based ceramic matrix composite (CMC) may be deposited (using conditions known to those skilled in the art) by one of the following methodologies: Atmospheric Plasma Spray (APS), High Velocity Oxy-Fuel (HVOF), Combustion Spray, Vacuum Plasma Spray, or Suspension Spray. For example, in embodiments where the Si-based bond coat and EBC top coat are deposited on the Si-based ceramic matrix composite (CMC) via APS, the conditions shown in Table 5 (below) may be used. [Table 5]

[0048] In some embodiments, the low melting temperature material(s) may be specifically selected and provided to the EBC in an effective amount that allows at or below a predetermined heat treatment temperature, at least a portion of the selected low melting temperature material(s) to melt, diffuse, and at least partially fill microstructural defects, such as microcracks and splat boundaries, that arise during EBC deposition. In a preferred embodiment, the low melting temperature material(s) may be specifically selected and provided to the EBC in an effective amount that allows at or below a predetermined heat treatment temperature, at least a portion of the selected low melting temperature material(s) to melt, diffuse, and substantially fill microstructural defects, such as microcracks and splat boundaries, that arise during EBC deposition (e.g., fill at least 90% or at least 95% of the initially present microstructural defect volume). Due to the reduced microstructural defects, some embodiments of the present disclosure include EBCs containing low melting temperature materials that provide enhanced oxidant diffusion blocking and more than two times (e.g., more than five times or more than ten times (e.g., on the order of 5 to 20 times)) slower TGO growth rates compared to coatings that do not include the low melting temperature material.

[0049] In some embodiments, the low temperature material is present in the EBC topcoat layer in an amount ranging from 0.1 wt % to 40 wt %, based on the total weight of the EBC topcoat layer. In other embodiments, the low temperature material is present in the EBC topcoat layer in an amount ranging from 0.5 wt % to 10 wt %, based on the total weight of the EBC topcoat layer. In yet other embodiments, the low temperature material is present in the EBC topcoat layer in an amount ranging from 1.0 wt % to 5.0 wt %, based on the total weight of the EBC topcoat layer.

[0050] In some embodiments, the EBC of the present disclosure may be prepared by a method that includes a post-coating heat treatment process. In such embodiments, the heat treatment temperature may be an effective (i.e., sufficiently high) temperature to allow the low melting temperature material to melt and diffuse into the matrix structure of the EBC (e.g., the matrix structure formed by the high melting temperature matrix material), such as a temperature equal to or at least 50°C higher than the melting temperature of the low melting temperature material, or a temperature in the range of 50°C to 150°C higher than the melting temperature of the low melting temperature material. In some embodiments, the heat treatment temperature may be a temperature sufficient to ensure that 100% of the low melting temperature material is completely melted to form a liquid phase. For example, the heat treatment temperature may be equal to or at least 100°C higher than the melting temperature of the low melting temperature material to ensure that the low melting temperature material is completely melted to form a liquid phase in the environmental barrier coating matrix (the EBC matrix formed by the high melting temperature matrix material) and fill the microcracks in the EBC.

[0051] The invention is further illustrated by the following non-limiting examples, in which all parts, percentages, proportions and ratios are by weight, all temperatures are in °C, and all pressures are atmospheric, unless otherwise indicated. EXAMPLES

[0052] Several specific EBCs have been prepared as exemplary embodiments of the innovations disclosed herein, and these examples are included herein for illustrative purposes.

[0053] In this example, Metco 4810 Si powder was used for the bond coat deposition and M6157 Yb2Si2O7 powder was used for the baseline topcoat deposition. The Yb2Si2O7 / Si baseline EBC as well as the Yb2Si2O7 containing low melting temperature phase / Si were deposited on SiC substrates using a SinplexPro plasma torch with a 9 mm nozzle.

[0054] All of the as-sprayed coatings were further annealed at 1300 °C for 10 h in air atmosphere. The heat treated EBCs were isothermally evaluated in a steam furnace at 1316 °C to investigate the growth behavior of the thermally grown oxide (TGO). Water was injected into the furnace along with air using a peristaltic pump. The amount of water and air was controlled to create an environment with about 90 vol.% H2O(g) and about 10 vol.% air, where a gas velocity of 4 cm / s was present in the thermal zone of the furnace chamber. The thickness of the thermally grown oxide (TGO) for various exposure times was measured using a scanning electron microscope (SEM).

[0055] Example 1: Figure 3 shows an SEM image of a high melting temperature matrix powder 320 composed of Metco 6157 Yb2Si2O7, which has a high melting temperature of about 1850° C., and a low melting temperature powder 330 composed of sodium calcium magnesium aluminosilicate powder, which has a melting temperature of about 1140° C. In Figure 3, the light phase is Yb2Si2O7 and the dark phase is the sodium calcium magnesium aluminosilicate powder.

[0056] Comparative Example 1A: Figure 4A shows an SEM image of an as-sprayed APS Yb2Si2O7 coating. In Figure 4A, the SEM image shows microcracks and splat boundaries in the as-sprayed APS Yb2Si2O7 coating (e.g., at the boundary between two splats where remelting and / or recrystallization of material near the splat surface (during the thermal spray production process) results in an interface (between the splats) that has a different morphology than the material inside the splats).

[0057] Comparative Example 1B: Figure 4B shows an SEM image of a heat treated APS Yb2Si2O7 coating. In Figure 4B, the SEM image shows microcracks and splat boundaries in an APS Yb2Si2O7 coating that was heat treated at 1300°C for 10 hours.

[0058] Example 1A: Figure 4C shows an SEM image of the as-sprayed APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating. In Figure 4C, the SEM image shows microcracks and splat boundaries in the as-sprayed APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating. Figure 4C also shows the distribution of sodium calcium magnesium aluminosilicate phase 410 in the Yb2Si2O7 matrix 420.

[0059] Example 1B: Figure 4D shows an SEM image of a heat treated APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating. In Figure 4D, the SEM image shows the disappearance of microcracks and splat boundaries, as well as the disappearance of the low melting sodium calcium magnesium aluminosilicate phase in the APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coating heat treated at 1300°C for 10 hours.

[0060] Comparative Example 1C: Figure 5A shows an SEM image of a Yb2Si2O7 coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 170 hours of exposure time. In Figure 5A, the SEM image shows a TGO thickness of about 6 μm in the Yb2Si2O7 coating.

[0061] Comparative Example 1D: Figure 5B shows an SEM image of the Yb2Si2O7 coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 510 hours of exposure time. In Figure 5B, the SEM image shows a TGO thickness of about 13.5 μm in the Yb2Si2O7 coating.

[0062] Example 1C: Figure 5C shows an SEM image of the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 170 hours of exposure time. In Figure 5C, the SEM image shows a TGO thickness of about 0.67 μm for the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating.

[0063] Example 1D: Figure 5D shows an SEM image of the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 510 hours of exposure time. In Figure 5D, the SEM image shows a TGO thickness of about 1.1 μm for the Yb2Si2O7-sodium calcium magnesium aluminosilicate coating.

[0064] 6 is a graph showing TGO thickness as a function of exposure in 90 vol. % H2O-10 vol. % air at 1316° C. for Yb2Si2O7 coatings and APS Yb2Si2O7-sodium calcium magnesium aluminosilicate coatings. In FIG. 6, the TGO growth rate in the EBC containing the low melting temperature sodium calcium magnesium aluminosilicate is about 10 times slower than the growth rate of the Yb2Si2O7 coating.

[0065] Example 2: Figure 7 shows an SEM image of a high melting temperature matrix powder 720 composed of Metco 6157 Yb2Si2O7, which has a high melting temperature of about 1850° C., and a low melting temperature powder 730 composed of Li2O, which has a melting temperature of about 1438° C. In Figure 7, the light phase is Yb2Si2O7 and the dark phase is the Li2O powder.

[0066] Example 2A: Figure 8A shows an SEM image of the as-sprayed APS Yb2Si2O7-0.4 wt% Li2O coating. In Figure 8A, the SEM image shows microcracks 810. Figure 8A also shows the distribution of Li2O820 in the Yb2Si2O7 matrix.

[0067] Example 2B: Figure 8B shows an SEM image of a heat treated APS Yb2Si2O7-0.4 wt% Li2O coating. In Figure 8B, the SEM image shows the disappearance of microcracks and indicates that the coating is densified in the APS Yb2Si2O7-0.4 wt% Li2O coating heat treated at 1300°C for 10 hours.

[0068] Comparative Example 2A: Figure 9A shows an SEM image of a Yb2Si2O7 coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 410 hours of exposure time. In Figure 9A, the SEM image shows a TGO thickness of about 11.3 μm for the Yb2Si2O7 coating.

[0069] Example 2C: Figure 9B shows an SEM image of the Yb2Si2O7-0.4 wt% Li2O coating evaluated in 90 vol% H2O-10 vol% air at 1316°C after 410 h exposure time. In Figure 9B, the SEM image shows a TGO thickness of about 6.5 μm for the Yb2Si2O7-0.4 wt% Li2O coating.

[0070] Furthermore, at least because the invention is disclosed herein in a manner that enables it to be made and used by disclosure of certain exemplary embodiments, e.g., for purposes of simplicity or efficiency, the invention may be practiced in the absence of any additional elements or additional structure not specifically disclosed herein.

[0071] It should be noted that the foregoing examples are provided for illustrative purposes only and are not to be construed as limiting the present invention in any way. Although the present invention has been described with reference to exemplary embodiments, it should be understood that the terms used herein are terms of description and illustration, rather than terms of limitation. Changes may be made within the scope of the appended claims, as currently stated and amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the details disclosed herein. Rather, the present invention extends to all functionally equivalent structures, methods and uses, as fall within the scope of the appended claims.

Claims

1. A raw material for supplying thermal spraying materials, (a) A first powder comprising at least one low melting temperature material having a melting temperature of less than 1500°C, (b) A second powder comprising at least one environmentally resistant coating matrix material, A raw material for supplying thermal spraying materials, including the above.

2. The thermal spray material supply raw material according to claim 1, wherein the at least one low melting temperature material is a monooxide compound, a binary oxide, a ternary oxide, or a complex oxide.

3. The thermal spray material supply raw material according to claim 1 or 2, wherein the low melting temperature material is a complex oxide comprising at least four oxides having a melting temperature of less than 1300°C.

4. The aforementioned at least one environmentally resistant coating matrix material is a rare earth silicate, a rare earth oxide, mullite, an alkali silicate, or HfO ２ , HfSiO ４ , HfTiO ４ ZrTiO ４ ZrSiO ４ Rare earth oxide-stabilized zirconia, rare earth oxide-stabilized hafnia, HfB ２ HfC, ZrB ２ The thermal spray material supply raw material according to claim 1 or 2, comprising at least one high melting temperature matrix material selected from the group consisting of , ZrC, and SiC.

5. The thermal spray material feedstock according to claim 1 or 2, wherein the first powder and the second powder are blended, agglomerated, agglomerated and sintered, plasma densified, or melted and pulverized.

6. The at least one low melting temperature material is CaO, MgO, Al ２ O ３ , SiO ２ , Na ２ O, K ２ O, and Fe ２ O ３ The thermal spraying material supply raw material according to claim 1 or 2, comprising the same.

7. The above-mentioned at least one low melting temperature material is Li ２ A thermal spray material supply raw material according to claim 1 or 2, wherein the raw material is O.

8. Environmental Barrier Coating (EBC), (I) EBC top coat, (i) Rare earth silicates, rare earth oxides, mullite, alkali silicates, HfO ２ , HfSiO ４ , HfTiO ４ ZrTiO ４ ZrSiO ４ Rare earth oxide-stabilized zirconia, rare earth oxide-stabilized hafnia, HfB ２ HfC, ZrB ２ An EBC matrix comprising at least one selected from the group consisting of ZrC and SiC, (ii) At least one low melting temperature material having a melting temperature of less than 1500°C, embedded in the EBC matrix, EBC top coat, (II) Si-based bonding coat and Environmentally resistant coatings (EBC), including those mentioned above.

9. The above-mentioned at least one low melting temperature material is CaO, MgO, Al ２ O ３ SiO ２ Na ２ O, K ２ O, and Fe ２ O ３ The EBC according to claim 8, including the EBC described in claim 8.

10. The above-mentioned at least one low melting temperature material is Li ２ The EBC according to claim 8, wherein O.

11. The EBC according to claim 8 or 9, wherein the EBC matrix comprises at least one rare earth silicate containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

12. The EBC according to claim 8 or 9, wherein the EBC matrix comprises at least one rare earth oxide containing at least one rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

13. The EBC according to claim 8 or 9, wherein the concentration of the at least one low-temperature material in the EBC matrix is ​​in the range of 0.1% by weight to 40% by weight, based on the total weight of the EBC topcoat.

14. The EBC according to claim 8 or 9, wherein the concentration of the at least one low-temperature material in the EBC matrix is ​​in the range of 0.4% by weight to 10% by weight, based on the total weight of the EBC topcoat.

15. The EBC according to claim 8 or 9, wherein the concentration of the at least one low-temperature material in the EBC matrix is ​​in the range of 0.4% by weight to 5.0% by weight, based on the total weight of the EBC topcoat.

16. A method for coating EBC onto a Si-based ceramic matrix composite (CMC), wherein the method is A method comprising depositing the EBC described in claim 8 onto the Si-based CMC.

17. The method according to claim 16, wherein the deposition is carried out by air plasma spraying (APS), high-velocity oxygen-fuel (HVOF), combustion spraying, vacuum plasma spraying, or suspension spraying.

18. It is EBC top coat, (i) Rare earth silicates, rare earth oxides, mullite, alkali silicates, HfO ２ , HfSiO ４ , HfTiO ４ ZrTiO ４ ZrSiO ４ Rare earth oxide-stabilized zirconia, rare earth oxide-stabilized hafnia, HfB ２ HfC, ZrB ２ An EBC matrix comprising at least one selected from the group consisting of ZrC and SiC, (ii) At least one low melting temperature material having a melting temperature of less than 1500°C, embedded in the EBC matrix, EBC top coat, including

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