Integrated preparation method of SiC-based composite material environment barrier coating

Abstract

The invention discloses an integrated preparation method of a SiC-based composite material environment barrier coating in the technical field of aviation thermal structure materials, which comprises the following steps: cleaning a substrate, carrying out vacuum impregnation of phenolic resin and curing, coating Si slurry to form a bonding layer, coating rare earth silicate slurry to form a barrier layer, and drying to obtain the SiC-based composite material environment barrier coating. And finally carrying out high-temperature heat treatment in an inert atmosphere. According to the method, through an integrated slurry coating and gradient curing process, the performance of a base body is protected, and meanwhile efficient preparation of the coating is achieved; by adopting an integrated slurry coating and gradient curing technology and combining with an optimized medium-temperature sintering process, the matrix performance is effectively protected while the compactness of the coating is ensured, the bonding strength and interface stability of the coating are improved through the design of the phenolic resin transition layer and the silicon bonding layer in cooperation with the rare earth silicate barrier layer, and the bonding strength of the coating is improved. And the coating shows excellent protection performance in a high-temperature corrosion environment.

Description

Technical Field

[0001] This invention relates to the field of aerospace thermal structure materials technology, and in particular to an integrated preparation method for a SiC-based composite environmental barrier coating. Background Technology

[0002] SiC-based composite materials are high-performance ceramic matrix composites (CMCs) with SiC fibers as reinforcement and SiC matrix as continuous phase. They have advantages such as low density (2.5-2.8 g / cm3, only 1 / 4-1 / 3 of the density of high-temperature alloy materials), high specific strength and specific modulus. In particular, they have excellent high temperature resistance, oxidation resistance and corrosion resistance in ultra-high temperature environments, and have become a key thermal structural material supporting the development of high-performance aero-engines.

[0003] Although SiC-based composites can react with oxygen in high-temperature, dry environments to form a protective SiO2 layer, which enhances their high-temperature stability, this stability deteriorates drastically in the service environment of aero-engines, rendering the bare SiC matrix unusable. An effective way to overcome this bottleneck is to prepare environmental barrier coatings (EBCs) on the surface of SiC-based composites, exhibiting excellent resistance to water and oxygen corrosion, combustion gas erosion, and thermal shock. Environmental barrier coatings are widely used in high-temperature service environments such as aero-engines, gas turbines, and nuclear reactors, and are a key technology for improving material durability and reliability.

[0004] Environmental barrier coatings (EBCs) are generally designed as a two-layer structure, consisting of a top layer and an adhesive layer from the outside in. The two layers of an EBC have different properties. The top layer is directly exposed to the external environment, providing the first layer of thermal insulation and corrosion protection. The adhesive layer improves the matching of modulus and coefficient of thermal expansion (CTE) between the coating system and the substrate, and enhances the adhesion strength between the substrate and the entire coating system. Currently, the mainstream EBC coating system is a Si adhesive layer + rare earth silicate topcoat system. The main function of the adhesive layer is to match the modulus and coefficient of thermal expansion of the coating system and the substrate, and to enhance the adhesion strength between the substrate and the entire coating system.

[0005] In existing technologies, the preparation processes for two-layer coatings of EBCs mainly employ plasma spraying, supersonic flame spraying, and low-pressure plasma spraying. However, these processes all require high-temperature treatment at 5000℃-10000℃, which means that the composite material needs to undergo a high-temperature treatment for each layer of coating. This not only causes crystallization of the SiC matrix but may also reduce the strength of the surface fibers, ultimately leading to a decline in the mechanical properties of the composite material. Therefore, we propose an integrated preparation method for SiC-based composite environmental barrier coatings. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides an integrated preparation method for an environmental barrier coating on SiC-based composite materials. A phenolic resin coating and a Si bonding layer are prepared on the surface of the SiC-based composite material, and then an environmental barrier coating is prepared by a slurry brushing method. After high-temperature heat treatment, an environmental barrier coating with high bonding strength is obtained, thereby overcoming the shortcomings of existing technologies.

[0007] The objective of this invention is achieved as follows: an integrated preparation method for a SiC-based composite environmental barrier coating, comprising the following steps: S1, Material pretreatment: Prepare the composite matrix, and after ultrasonic cleaning with a cleaning solution, dry it for later use; S2, Preparation of phenolic resin coating: Dissolve phenolic resin in an organic solvent, stir to dissolve and obtain phenolic resin solution, put the composite matrix into an impregnation tank, perform vacuum treatment, inject phenolic resin solution for impregnation treatment, take out the composite matrix and drain the excess phenolic resin solution, perform gradient drying and curing to complete the preparation of phenolic resin coating. S3, Preparation of the adhesive layer: Si powder and fusion agent are mixed and ball-milled. Then, binder and organic solvent are added and stirred to prepare Si slurry. Finally, Si slurry is coated on the outside of phenolic resin coating and solidified into adhesive layer. S4, Preparation of environmental barrier coating: The barrier coating material is mixed with an organic solvent to prepare a barrier layer slurry, and the barrier layer slurry is coated on the outside of the composite matrix adhesive layer to prepare an environmental barrier coating; S5, Heat treatment: The composite matrix coated with the barrier layer is subjected to high-temperature heat treatment and inert protection.

[0008] Optionally, in step S1, the composite material includes boron fiber, carbon fiber and silicon carbide fiber, and all of the composite materials are toughened.

[0009] Optionally, in step S2, the mass ratio of phenolic resin in the phenolic resin solution is 1:30 to 1:5, the viscosity of the phenolic resin solution is 1 to 20 mPa·s, and the thickness of the phenolic resin coating is adjusted by adjusting the viscosity of the solution, wherein the thickness of the phenolic resin coating is 10 to 200 μm.

[0010] Optionally, in step S2, the organic solution is an organic solvent that can dissolve phenolic resin, specifically including anhydrous ethanol, acetone, tetrahydrofuran, xylene, and toluene.

[0011] Optionally, the gradient drying and curing specifically involves: after draining the composite material matrix, air-drying it and then placing it in an oven; 1) First, cure at 120℃~130℃ for 2~5 hours; 2) Heat to 140℃~160℃ and cure for 2~5 hours; 3) Finally, heat to 180℃~200℃ and cure for 2 to 5 hours before removing.

[0012] Optionally, in step S3, the fusion agent includes anhydrous ethanol, acetone, tetrahydrofuran, xylene, toluene, and liquid polycarbosilane.

[0013] Optionally, in step S3, the particle size of the Si powder is 1~5μm; The mass ratio of Si powder to solution in the Si slurry is 1:20 to 1:1, and the viscosity of the Si slurry is 20 to 200 mPa·s. The thickness of the adhesive layer is 10~500μm.

[0014] Optionally, in step S4, the barrier coating material includes rare earth silicates and high-entropy rare earth silicates; The particle size of the barrier coating material is 1~15μm.

[0015] Optionally, the mass ratio of the barrier coating material in the barrier layer slurry to the solution is 1:20 to 1:1, and the viscosity of the barrier layer slurry is 20 to 200 mPa·s; The thickness of the environmental barrier coating is 50~500μm.

[0016] Optionally, in step S5, the inert protection specifically refers to protection with a non-reactive atmosphere or a vacuum state; The high-temperature heat treatment specifically involves a heat treatment temperature of 1200~1500℃, a heating rate of 1~30℃ / min, and a holding time of 0.5~10h.

[0017] Compared with the prior art, the present invention adopts an integrated slurry coating and gradient curing technology, combined with an optimized medium-temperature sintering process, which effectively protects the substrate performance while ensuring the density of the coating. Through the design of phenolic resin transition layer and silicon bonding layer, combined with rare earth silicate barrier layer, the coating bonding strength and interface stability are improved, so that the coating exhibits excellent protective performance in high-temperature corrosive environment. By precisely controlling the slurry system and curing process, flexible control and uniform coverage of coating thickness can be achieved. It is applicable to composite material systems reinforced with different fibers. The integrated single sintering process not only simplifies the preparation process, but also avoids the interface defects caused by traditional multi-step high-temperature treatment. It provides a reliable and efficient solution for the industrial production of complex components and has broad application prospects in the field of high-temperature protection. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Fig. 1 This is a schematic diagram of the overall process steps provided by the present invention.

[0020] Fig. 2 This is a schematic diagram of the process framework provided by the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] like Figs. 1-2 The method for preparing an integrated SiC-based composite environmental barrier coating includes the following steps: S1, Material pretreatment: Prepare the composite matrix, and after ultrasonic cleaning with a cleaning solution, dry it for later use; S2, Preparation of phenolic resin coating: Dissolve phenolic resin in an organic solvent, stir to dissolve and obtain phenolic resin solution, put the composite matrix into an impregnation tank, perform vacuum treatment, inject phenolic resin solution for impregnation treatment, take out the composite matrix and drain the excess phenolic resin solution, perform gradient drying and curing to complete the preparation of phenolic resin coating. S3, Preparation of the adhesive layer: Si powder and fusion agent are mixed and ball-milled. Then, binder and organic solvent are added and stirred to prepare Si slurry. Finally, Si slurry is coated on the outside of phenolic resin coating and solidified into adhesive layer. S4, Preparation of environmental barrier coating: The barrier coating material is mixed with an organic solvent to prepare a barrier layer slurry, and the barrier layer slurry is coated on the outside of the composite matrix adhesive layer to prepare an environmental barrier coating; S5, Heat treatment: The composite matrix coated with the barrier layer is subjected to high-temperature heat treatment and inert protection.

[0023] Specifically, in step S1, the composite material includes boron fiber, carbon fiber and silicon carbide fiber, and all of the composite materials are toughened.

[0024] Furthermore, when cleaning the composite material, firstly, ultrasonic cleaning with acetone and ethanol is performed for 30-60 minutes, and then the composite material is placed in an oven at 70°C to dry for 2 hours. It should be noted that ultrasonic cleaning with acetone and ethanol for 30 to 60 minutes before coating the composite matrix can effectively remove surface organic contaminants (such as grease and resin residue) and some inorganic oxide layers, thereby improving the wettability of subsequent coatings or resins. Secondly, drying at 70℃ for 2 hours ensures complete solvent evaporation, preventing residues from generating bubbles or cracks during high-temperature sintering. This ensures good interfacial bonding between the fiber and the matrix / coating, improving the mechanical properties and oxidation resistance of the composite material.

[0025] Specifically, in step S2, the organic solution is an organic solvent that can dissolve phenolic resin, specifically including anhydrous ethanol, acetone, tetrahydrofuran, xylene, and toluene.

[0026] Specifically, in step S2, the mass ratio of phenolic resin to the solution in the phenolic resin solution is 1:30 to 1:5, the viscosity of the phenolic resin solution is 1 to 20 mPa·s, and the thickness of the phenolic resin coating is adjusted by adjusting the viscosity of the solution, wherein the thickness of the phenolic resin coating is 10 to 200 μm.

[0027] Furthermore, by adjusting the concentration and viscosity of the phenolic resin solution, the thickness of the coating can be flexibly adjusted. Lower viscosity helps to form a uniform thin coating, ensuring that the fiber surface is completely covered while reducing coating defects. Higher viscosity is suitable for preparing thicker coatings, which not only enhances the bonding strength between the fiber and the matrix but also provides more effective antioxidant protection.

[0028] The principle is that the viscosity of the solution directly determines its fluidity and its ability to wet fibers. If the viscosity is too low, the coating may be unevenly distributed, while if the viscosity is too high, it will affect the permeability and density of the coating. This control method can optimize the functional performance of the coating while ensuring the stability of the process.

[0029] Furthermore, after placing the SiC-based composite material into the impregnation tank, it needs to be subjected to a vacuum treatment, with the vacuum level set to 10. -2 ~10 -3 After applying MPa and holding for 30 minutes, inject phenolic resin solution to ensure complete coverage of the substrate. Keep the substrate immersed for 1–2 hours, then remove and drain excess resin to avoid surface buildup.

[0030] Specifically, the gradient drying and curing process involves: after draining the composite material matrix, air-drying it and then placing it in an oven; 1) First, cure at 120℃~130℃ for 2~5 hours; 2) Heat to 140℃~160℃ and cure for 2~5 hours; 3) Finally, heat to 180℃~200℃ and cure for 2 to 5 hours before removing.

[0031] Furthermore, the gradient drying and curing in step S2 adopts a staged heating method. First, the resin is pre-cured at a low temperature to allow it to initially cross-link and release volatiles, and then the temperature is gradually increased to promote the deep curing of the resin. The advantages of using this processing technology are: on the one hand, it can avoid the internal stress concentration or bubble defects caused by the rapid reaction of resin at high temperature, ensuring uniform curing and dense structure; on the other hand, the gradual heating can optimize the arrangement of resin molecular chains and improve the mechanical strength and thermal stability of composite materials. Furthermore, staged curing not only controls the reaction rate but also allows for the full release of volatiles, thereby reducing internal stress and enhancing interfacial bonding, resulting in composite materials with superior performance.

[0032] Specifically, in step S3, the fusion agent includes anhydrous ethanol, acetone, tetrahydrofuran, xylene, toluene, and liquid polycarbosilane; The particle size of the Si powder is 1~5μm; The mass ratio of Si powder to solution in the Si slurry is 1:20 to 1:1, and the viscosity of the Si slurry is 20 to 200 mPa·s. The thickness of the adhesive layer is 10~500μm.

[0033] Specifically, in step S4, the barrier coating material includes rare earth silicates and high-entropy rare earth silicates; The particle size of the barrier coating material is 1~15μm.

[0034] Furthermore, the fusion agent is also an organic solvent, mainly using anhydrous ethanol as the fusion agent, which can effectively adjust the solubility and dispersibility of Si slurry, while the fine particle size of Si powder helps to form a uniform and dense adhesive layer. Furthermore, by adjusting the ratio and viscosity of the Si slurry, the fluidity and permeability of the coating can be flexibly controlled, ensuring that the adhesive layer has a moderate thickness and uniform distribution. A thinner adhesive layer is beneficial to improving the interfacial bonding strength, while a thicker adhesive layer can enhance the anti-oxidation and anti-ablation properties.

[0035] Therefore, this design ensures process adaptability while optimizing the mechanical properties and high-temperature resistance of the coating, thereby improving the overall reliability of the composite material.

[0036] Specifically, the mass ratio of the barrier coating material to the solution in the barrier layer slurry is 1:20 to 1:1, and the viscosity of the barrier layer slurry is 20 to 200 mPa·s; The thickness of the environmental barrier coating is 50~500μm.

[0037] Specifically, in step S5, the inert protection specifically refers to the use of a non-reactive atmosphere or a vacuum state. The high-temperature heat treatment specifically involves a heat treatment temperature of 1200~1500℃, a heating rate of 1~30℃ / min, and a holding time of 0.5~10h.

[0038] Furthermore, the use of a non-reactive atmosphere or vacuum can effectively prevent harmful reactions between materials and gases at high temperatures, ensuring the purity of the sintering process and inhibiting oxidation or impurity formation. Furthermore, high-temperature heat treatment, through precise control of the heating rate and holding time, fully densifies the internal structure of the material and optimizes grain growth, thereby improving the mechanical properties and thermal stability of the final product. In addition, a moderate heating rate can reduce the risk of cracks caused by thermal stress, while a reasonable holding time ensures that the reaction is fully completed and avoids over-sintering or energy waste.

[0039] Example 1: An environmental barrier coating (Y2Si2O7) of C / SiC composite material was prepared using the method of the present invention: (1) Resin coating preparation: Phenolic resin is dissolved in anhydrous ethanol, and the mass ratio of phenolic resin to anhydrous ethanol is 1:10; C / SiC composite material (prepared by chemical vapor deposition, density greater than 2.0 g / cm3) and resin solution are placed in a vacuum tank at the same time, and the vacuum is maintained at -0.08 MPa to -0.10 MPa for 20 minutes. The C / SiC composite material is taken out and cooled at room temperature for 3 hours. It is then cured in an oven at 120℃ to 130℃ for 2 to 5 hours, cured at 140℃ to 160℃ for 2 to 5 hours, and cured at 180℃ to 200℃ for 2 to 5 hours.

[0040] (2) Preparation of Si bonding layer: Si powder of 1~3μm composite matrix is ​​mixed with anhydrous ethanol to make a slurry. The mass of Si powder is 10% of the mass of anhydrous ethanol. The viscosity of the slurry is controlled to be 100~200mPa·s by controlling the content of anhydrous ethanol. The slurry is coated on the C / SiC composite material containing resin coating by casting or other methods to make Si bonding layer.

[0041] (3) Preparation of environmental barrier coating: The environmental barrier coating (Y2Si2O7) was prepared by slurry method. Y2Si2O7 powder and anhydrous ethanol were mixed to form a slurry. The mass of Y2Si2O7 powder was 50% of the mass of anhydrous ethanol. The slurry was coated on the C / SiC composite material containing Si binder layer by casting and other methods to form an environmental barrier coating with a thickness of 250μm.

[0042] (4) Heat treatment: The C / SiC composite material with the prepared coating was heat treated at 1500℃ for 1h to obtain the final C / SiC composite material with an environmental barrier coating. As a comparison, the same environmental barrier coating was prepared on the surface of the C / SiC composite material in step (2) by atmospheric plasma spraying (APS) and annealed at 1300℃ under Ar gas protection for 3h.

[0043] (5) The bonding strength of the coating was tested by tensile testing of the mating parts according to the standard: HB Composite Matrix 5476-1991 "Test Method for Bonding Strength of Thermal Spray Coating on Composite Matrix" with a loading rate of 2 mm / min. The present invention yields a coating bonding strength of 15 MPa, while the bonding strength of the adhesive layer prepared by the APS method is only 10 MPa, which is significantly lower than that of the adhesive layer prepared by the method of the present invention, proving that the adhesive layer obtained by the present invention has a higher bonding strength.

[0044] Example 2: An environmental barrier coating (high entropy rare earth silicate, (Yb0.2Y0.2Lu0.2Sc0.2Gd0.2)2Si2O7) of SiC / SiC composite material was prepared using the method of the present invention.

[0045] (1) Resin coating preparation: Phenolic resin is dissolved in anhydrous ethanol, and the mass ratio of phenolic resin to anhydrous ethanol is 1:10; SiC / SiC composite material (prepared by chemical vapor deposition, density greater than 2.6 g / cm3) and resin solution are placed in a vacuum tank at the same time, and the vacuum is drawn to -0 composite matrix 0.08 MPa to -0.10 MPa for 20 minutes. The SiC / SiC composite material is taken out and cooled at room temperature for 3 hours. It is then cured in an oven at 120℃ to 130℃ for 2 to 5 hours, cured at 140℃ to 160℃ for 2 to 5 hours, and cured at 180℃ to 200℃ for 2 to 5 hours.

[0046] (2) Preparation of Si bonding layer: Si powder of 1~3μm composite matrix is ​​mixed with anhydrous ethanol to make a slurry. The mass of Si powder is 10% of the mass of anhydrous ethanol. The viscosity of the slurry is controlled to be 100~200mPa·s by controlling the content of anhydrous ethanol. The slurry is coated on the SiC / SiC composite material containing resin coating by casting or other methods to make Si bonding layer.

[0047] (3) Preparation of environmental barrier coating: The environmental barrier coating (high entropy rare earth silicate, (Yb0.2Y0.2Lu0.2Sc0.2Gd0.2)2Si2O7) was prepared by slurry method. The above powder was mixed with anhydrous ethanol to form a slurry, and the mass of the powder was 50% of the mass of anhydrous ethanol. The slurry was coated on the SiC / SiC composite material containing the Si binder layer by casting and other methods to form an environmental barrier coating with a thickness of 200μm.

[0048] (4) Heat treatment: The SiC / SiC composite material with the prepared coating was heat-treated at 1400℃ for 2h to obtain the final SiC / SiC composite material with an environmental barrier coating. As a comparison, the same environmental barrier coating was prepared on the surface of the SiC / SiC composite material in step (2) by atmospheric plasma spraying (APS) and annealed at 1300℃ under Ar gas protection for 3h.

[0049] (5) The samples were subjected to a high-temperature water-oxygen vapor corrosion test at a temperature of 1400℃. The water vapor mass fraction in the water-oxygen vapor atmosphere was 90%, and the oxygen mass fraction was 10%. After 500 hours of high-temperature water-oxygen vapor corrosion, the samples were removed and subjected to a bending strength test. The bending strength retention rate of the material was calculated, and the bending strength retention rate was 90%. Compared with the adhesive layer prepared by the APS method, the bending strength retention rate after high-temperature water-oxygen corrosion was only 80%, which proves that the environmental barrier coating prepared by the method of the present invention has better corrosion resistance and protective effect.

[0050] In summary, compared with traditional high-temperature processes such as plasma spraying and supersonic flame spraying, the present invention has the following significant advantages: First, traditional methods require multiple ultra-high temperature treatments of 5000℃~10000℃, which can easily lead to crystallization of the SiC matrix and degradation of fiber strength. This invention employs a slurry coating + low-temperature curing + single high-temperature heat treatment (1200~1500℃) to significantly reduce the risk of thermal damage while preserving the mechanical properties of the composite material. Secondly, by using a gradient design of the composite matrix matrix consisting of a phenolic resin transition layer, a Si bonding layer, and an environmental barrier coating, combined with a vacuum impregnation and staged curing process, the interfacial bonding strength is significantly improved (the bonding strength in Example 1 reaches 15 MPa, which is better than the 10 MPa of the traditional APS method). Precisely control the viscosity and ratio of the slurry (e.g., Si slurry viscosity 20~200mPa·s) to ensure a uniform and dense coating and reduce porosity and crack defects; Third, the rare earth silicate / high entropy rare earth silicate barrier layer composite matrix, combined with the inert atmosphere / vacuum heat treatment of the composite matrix, effectively inhibits water and oxygen corrosion (the bending strength retention rate of Example 2 after 500h high temperature water and oxygen corrosion is 90%, which is better than the 80% of the APS method); the Si bonding layer composite matrix is ​​oxidized at high temperature to generate SiO2, which further fills the microcracks and forms a self-healing protection mechanism.

[0051] Finally, by adjusting parameters such as the resin concentration of the composite matrix, the slurry ratio, the curing temperature, and the composite matrix, different fiber (C / SiC, SiC / SiC) and coating requirements can be adapted. The low-temperature curing + single-sintering composite matrix simplifies the process, reduces energy consumption, and is suitable for industrial production.

[0052] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. An integrated preparation method for a SiC-based composite environmental barrier coating, characterized in that: Includes the following steps: S1, Material pretreatment: Prepare the composite matrix, and after ultrasonic cleaning with a cleaning solution, dry it for later use; S2, Preparation of phenolic resin coating: Dissolve phenolic resin in an organic solvent, stir to dissolve and obtain phenolic resin solution, put the composite matrix into an impregnation tank, perform vacuum treatment, inject phenolic resin solution for impregnation treatment, take out the composite matrix and drain the excess phenolic resin solution, perform gradient drying and curing to complete the preparation of phenolic resin coating. S3, Preparation of the adhesive layer: Si powder and fusion agent are mixed and ball-milled. Then, binder and organic solvent are added and stirred to prepare Si slurry. Finally, Si slurry is coated on the outside of phenolic resin coating and solidified into adhesive layer. S4, Preparation of environmental barrier coating: The barrier coating material is mixed with an organic solvent to prepare a barrier layer slurry, and the barrier layer slurry is coated on the outside of the composite matrix adhesive layer to prepare an environmental barrier coating; S5, Heat treatment: The composite matrix coated with the barrier layer is subjected to high-temperature heat treatment and inert protection.

2. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 1, characterized in that: In step S1, the composite material includes boron fiber, carbon fiber and silicon carbide fiber, and all of the composite materials are toughened.

3. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 1, characterized in that: In step S2, the mass ratio of phenolic resin to the solution in the phenolic resin solution is 1:30 to 1:5, and the viscosity of the phenolic resin solution is 1 to 20 mPa·s. The thickness of the phenolic resin coating is adjusted by adjusting the viscosity of the solution, and the thickness of the phenolic resin coating is 10 to 200 μm.

4. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 3, characterized in that: In step S2, the organic solution is an organic solvent that can dissolve phenolic resin, specifically including anhydrous ethanol, acetone, tetrahydrofuran, xylene, and toluene.

5. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 4, characterized in that: The gradient drying and curing process specifically involves: after draining the composite material matrix, air-drying it, and then placing it in an oven; 1) First, cure at 120℃~130℃ for 2~5 hours; 2) Heat to 140℃~160℃ and cure for 2~5 hours; 3) Finally, heat to 180℃~200℃ and cure for 2 to 5 hours before removing.

6. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 1, characterized in that: In step S3, the fusion agent includes anhydrous ethanol, acetone, tetrahydrofuran, xylene, toluene, and liquid polycarbosilane.

7. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 6, characterized in that: In step S3, the particle size of the Si powder is 1~5μm; The mass ratio of Si powder to solution in the Si slurry is 1:20 to 1:1, and the viscosity of the Si slurry is 20 to 200 mPa·s. The thickness of the adhesive layer is 10~500μm.

8. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 1, characterized in that: In step S4, the barrier coating material includes rare earth silicates and high-entropy rare earth silicates; The particle size of the barrier coating material is 1~15μm.

9. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 8, characterized in that: The barrier coating material in the barrier layer slurry has a mass ratio of 1:20 to 1:1 to the solution, and the viscosity of the barrier layer slurry is 20 to 200 mPa·s. The thickness of the environmental barrier coating is 50~500μm.

10. The integrated preparation method of a SiC-based composite environmental barrier coating according to claim 1, characterized in that: In step S5, the inert protection specifically refers to protection with a non-reactive atmosphere or a vacuum state; The high-temperature heat treatment specifically involves a heat treatment temperature of 1200~1500℃, a heating rate of 1~30℃ / min, and a holding time of 0.5~10h.

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