CN116715538B

CN116715538B - A self-healing environmental barrier coating resistant to high temperature oxidation for ceramic-based composite materials and a preparation method thereof

Info

Publication number: CN116715538B
Application number: CN202310712253.0A
Authority: CN
Inventors: 李佳艳; 李归; 王博; 谭毅
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2023-06-15
Filing date: 2023-06-15
Publication date: 2025-01-03
Anticipated expiration: 2043-06-15
Also published as: CN116715538A

Abstract

The invention provides a self-healing environment barrier coating for ceramic matrix composite materials and a preparation method thereof. The coating is of a double-layer structure and sequentially comprises a bonding layer and a self-healing coating from inside to outside, wherein the bonding layer is prepared on the surface of the silicon carbide ceramic matrix composite, and the self-healing coating is prepared on the surface of the bonding layer. The invention effectively improves the service temperature of the environment barrier coating, improves the oxidation resistance, improves the bonding strength of the coating and a matrix, effectively improves the anti-seismic service life of the coating, and effectively improves the service life of the environment barrier coating.

Description

High-temperature oxidation resistant self-healing environment barrier coating for ceramic matrix composite and preparation method thereof

Technical Field

The invention relates to the technical field of materials, in particular to a self-healing environment barrier coating for high-temperature oxidation resistance of a ceramic matrix composite material and a preparation method thereof.

Background

The thrust-weight ratio of the aeroengine is improved, and the inlet temperature of the gas before the turbine is required to be improved, but the traditional nickel-based superalloy cannot meet the current service temperature. Therefore, the ceramic matrix composite material with the advantages of low density, high melting point, excellent high-temperature mechanical property and the like is a material which is most hopeful to replace nickel-based superalloy to be applied to high-temperature parts of an aeroengine.

Under the dry high-temperature combustion environment, a compact SiO ₂ layer is generated on the surface of the ceramic matrix composite, so that the entry of oxygen can be effectively prevented, and the oxidation resistance is improved. However, in the actual operation process of the aeroengine, 8-10vol% of water vapor is generated in the combustion process of the aviation kerosene, siO ₂ reacts with the water vapor to generate Si (OH) _x, the ceramic matrix composite is severely corroded, and the mechanical property is severely reduced. Therefore, it is necessary to prepare an environmental barrier coating on the surface of the ceramic matrix composite to isolate high-temperature vapor and inhibit high-temperature oxygen corrosion, and the long-service life of the ceramic matrix composite hot end component is extremely important.

Si is the most widely used bonding layer in the environment barrier coating, improves the bonding strength of the environment barrier coating and the ceramic matrix composite, and simultaneously provides excellent oxidation resistance for the ceramic matrix composite. However, the oxidation product SiO ₂ of Si can cause the coating to drop and fail during cooling due to the stress created by the phase change. Furthermore, si has a melting point of 1414 ℃ which limits the use of environmental barrier coatings at higher temperatures. Therefore, it is necessary to develop a new material to increase the service temperature and oxidation and corrosion resistance of the environmental barrier coating.

The rare earth silicate is used as an environment barrier coating ceramic layer to play roles in isolating oxygen, fuel gas, combustion impurities and other harmful substances, and is generally prepared by adopting an atmospheric plasma spraying method. Atmospheric plasma spraying is widely applied to coating preparation as an economic and efficient coating preparation process, but the spraying conditions in the atmospheric environment easily oxidize non-oxides such as silicon, silicide, carbide and the like. Therefore, in the preparation process of the bonding layer, the coating is prepared by adopting a cold spraying method, and the bonding layer with no oxidation and high bonding strength can be effectively prepared by combining a solid phase sintering method under a protective atmosphere. In addition, rare earth silicate is decomposed in plasma flame, and the prepared coating has defects of cracks, air holes and the like due to quenching stress and thermal mismatch stress. By the doping method, the composite coating with the self-healing function can be prepared, defects such as cracks and air holes generated in the service process of the coating are inhibited, and the entry of oxygen and water vapor can be effectively prevented.

Disclosure of Invention

According to the technical problems, a self-healing environment barrier coating for ceramic matrix composite materials and a preparation method thereof are provided. The invention mainly prepares MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer) on the surface of the ceramic matrix composite material by preparing Mo-Si or Mo-W-Si mixed slurry and adopting two different methods of a more convenient cold spraying method and a slurry dipping method, avoids oxidation generated in the atmospheric plasma spraying process, prepares Re ₂SiO₅ -Si powder (Re= Yb, Y, gd, lu, nd) by adopting a spray granulation method, and prepares Re ₂SiO₅ -Si self-healing environment barrier coating on the surface of the bonding layer by adopting an atmospheric plasma method, thereby effectively improving the anti-seismic service life and the anti-oxidation capability of the coating.

The invention adopts the following technical means:

The self-healing environment barrier coating is of a double-layer structure and sequentially comprises a bonding layer and a self-healing coating from inside to outside, wherein the bonding layer is prepared on the surface of the silicon carbide ceramic matrix composite, and the self-healing coating is prepared on the surface of the bonding layer.

Further, the material of the adhesive layer is MoSi ₂ or (Mo _x,W_1-x)Si₂;

The self-healing coating is made of Re ₂SiO₅ -Si, wherein Re= Yb, Y, gd, lu or Nd;

the ceramic matrix composite is a silicon carbide ceramic matrix composite.

Further, the thickness of the bonding layer is 50-100 mu m, the self-healing coating is 100-200 mu m, and the size of the ceramic matrix composite is 50 multiplied by 5mm ³.

The invention also provides a preparation method of the self-healing environment barrier coating for the ceramic matrix composite material, which comprises the following steps:

s1, taking a silicon carbide ceramic matrix composite material continuously toughened by silicon carbide fibers as a matrix, and sequentially polishing, surface sand blasting, ultrasonic cleaning, alcohol soaking and drying the silicon carbide ceramic matrix composite material matrix for later use;

s2, preparing a bonding layer on the silicon carbide ceramic matrix composite material matrix by adopting a cold spraying method or a slurry dipping method;

s3, preparing a self-healing coating on the surface of the bonding layer by adopting an atmospheric plasma spraying method, so as to prepare a composite coating with a self-healing function, namely a self-healing environment barrier coating;

And S4, evaluating the performance of the sample, namely performing oxidation test, thermal shock test and flame thermal cycle test on the prepared self-healing environmental barrier coating sample.

Further, in the step S1, a silicon carbide ceramic matrix composite is polished into round corners by a diamond grinding head, the surface of the polished silicon carbide ceramic matrix composite is subjected to sand blasting by using 220-mesh corundum particles under the pressure of 0.3MPa for 15-20 seconds, absolute ethyl alcohol is used as a solvent, ultrasonic treatment is carried out on the sand blasted silicon carbide ceramic matrix composite for 5 minutes to remove impurities, the silicon carbide ceramic matrix composite is soaked in the absolute ethyl alcohol for 60 minutes to remove greasy dirt, and then the silicon carbide ceramic matrix composite is dried in an oven at the temperature of between 60 ℃ for 2 hours to prepare a coating.

Further, in the step S2, the method for preparing the adhesive layer by using the cold spraying method includes:

S21, weighing according to the mass ratio of Mo to Si in a binder=64:35:1 or weighing according to the mass ratio of Mo to W to Si in a binder=32:32:36:0.5, and performing ball milling by taking absolute ethyl alcohol as a solvent and zirconia balls as ball milling media at the ball milling speed of 500r/min for 4h to obtain a Mo-Si or Mo-W-Si mixed solution;

S22, performing cold spraying on the surface of the silicon carbide ceramic matrix composite material by using a cold spraying method, then performing two-step drying in an oven, drying at 60 ℃ for 24 hours, and then drying at 110 ℃ for 12 hours to obtain MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

Further, moSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer) prepared in the step S22 is subjected to solid-phase sintering for 2 hours at 1500 ℃ in a hot pressing furnace in an argon atmosphere, so that the coating is better combined with the silicon carbide ceramic matrix composite material matrix, and the process is repeated for a plurality of times to obtain the ideal thickness (50-100 mu m).

Further, in the step S2, the method for preparing the adhesive layer by using the slurry impregnation method includes:

S201, weighing Mo and Si raw materials according to the mass ratio of Mo to Si bonding agent=64:35:1, or weighing Mo to W to Si bonding agent=32:32:36:0.5, adopting a mechanical mixing ball milling and spray drying method to prepare Mo-Si or Mo-W-Si mixed powder, taking ethanol as a solvent, mixing the Mo-Si or Mo-W-Si mixed powder with the solvent, adding a certain mass of bonding agent, preparing slurry, and stirring in a constant-temperature magnetic stirrer for 2-3 hours;

S202, dipping a silicon carbide ceramic matrix composite material matrix into the slurry, slowly putting the slurry into a drying oven, drying the slurry for 24 hours at 60 ℃ and then drying the slurry for 12 hours at 110 ℃, putting the slurry into an argon atmosphere furnace for high-temperature sintering, and sintering the slurry for 2 hours at 1600 ℃ to prepare the MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

Further, the specific steps of the step S3 are as follows:

S31, taking rare earth silicate as a main material, adding 10-20wt% of Si, and adopting a mechanical mixing and spray granulation method to prepare Re ₂SiO₅ -Si composite powder with different rare earth elements, wherein the detailed preparation process comprises the steps of mixing Re ₂SiO₅ powder, si powder, deionized water, an Arabic gum binder and an ammonium citrate dispersing agent, ball milling to obtain slurry, and drying the slurry in a spray drying mode to obtain spherical granulated powder with the particle size of 32-125 mu m.

S32, spraying Re ₂SiO₅ -Si composite powder on the surface of the bonding layer by an atmospheric plasma spraying method to prepare the self-healing coating, thereby preparing the self-healing environmental barrier coating with the self-healing function. The preparation parameters of the atmospheric plasma are that the temperature of a matrix is preheated to 300-600 ℃ in the process of atmospheric plasma spraying, the power of a spray gun is 20-42kW, the spraying distance is 100-200mm, the powder feeding rate is 3-10%, and the spraying angle is 30-60 ℃.

Further, in the step S4, the oxidation test specifically comprises the steps of placing the self-healing environmental barrier coating sample at 1400 ℃ and 1500 ℃ respectively, carrying out static oxidation on the sample at each temperature for 2h, 16h, 32h and 64h, and observing the microscopic morphology of the coating and the substrate;

The thermal shock test specifically comprises the following steps of preserving the temperature of a sample at 1400 ℃ for 55min, cooling the sample with air for 5min, and respectively carrying out thermal shock for 16 times, 32 times and 64 times until the shedding area of the coating reaches 20% of the whole area, and stopping thermal shock;

the flame thermal cycle test specifically comprises the following steps of heating a sample for 5min by using a flame thermal cycle instrument, cooling for 2min, and respectively circulating for 200 times, 400 times and 800 times until the coating falling area reaches 20% of the whole area, and stopping the thermal cycle test.

Compared with the prior art, the invention has the following advantages:

1. According to the high-temperature oxidation resistant self-healing environment barrier coating for the ceramic matrix composite material and the preparation method thereof, moSi ₂ or (preparation of Mo _x,W_1-x)Si₂ bonding layer) effectively improves the service temperature of the environment barrier coating, improves the oxidation resistance and effectively prolongs the service life of the environment barrier coating.

2. According to the self-healing environment barrier coating for the ceramic matrix composite material and the preparation method thereof, provided by the invention, after a cold spraying method and a slurry dipping method are combined with a solid-phase reaction sintering method, oxidation of silicide in the preparation process of the coating is avoided, and the bonding strength of the coating and a matrix is improved.

3. According to the high-temperature oxidation resistant self-healing environment barrier coating for the ceramic matrix composite material and the preparation method thereof, the preparation of the self-healing composite coating effectively improves the thermal shock resistance life and the oxidation resistance of the coating. In the service process of the coating at the temperature of more than 1400 ℃, the molten Si fills the defects of pores, cracks and the like, so that a compact coating is formed, and the entry of harmful substances such as oxygen, water vapor and the like is inhibited. In addition, oxygen entering the coating is first consumed by Si, and the reaction product SiO ₂ reacts with the rare earth monosilicate to form pyrosilicate.

Based on the reasons, the invention can be widely popularized in the fields of aviation and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to the drawings without inventive effort to a person skilled in the art.

FIG. 1 is a schematic diagram of the coating structure of the present invention.

FIG. 2 is a flow chart of the coating preparation of the present invention.

Detailed Description

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Meanwhile, it should be clear that the dimensions of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters refer to like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

As shown in fig. 1, the invention provides a self-healing environment barrier coating for ceramic matrix composite, which is of a double-layer structure and sequentially comprises a bonding layer and a self-healing coating from inside to outside, wherein the bonding layer is prepared on the surface of a silicon carbide ceramic matrix composite, and the self-healing coating is prepared on the surface of the bonding layer. The bonding layer is made of MoSi ₂ or (Mo _x,W_1-x)Si₂; the self-healing coating is made of Re ₂SiO₅ -Si, wherein Re= Yb, Y, gd, lu or Nd; the ceramic matrix composite is made of silicon carbide ceramic matrix composite, the thickness of the bonding layer is 50-100 mu m, the self-healing coating is 100-200 mu m, and the size of the ceramic matrix composite is 50 multiplied by 5mm ³.

As shown in FIG. 2, the invention also provides a preparation method of the self-healing environment barrier coating for ceramic matrix composite material, which comprises the following steps:

1. The silicon carbide ceramic matrix composite material (50 multiplied by 5mm ³) continuously toughened by silicon carbide fibers is used as a matrix, and a diamond grinding head is adopted to grind a matrix sample into round corners in order to reduce stress concentration. And (3) carrying out sand blasting treatment on the polished substrate by using 220-mesh corundum particles under the pressure of 0.3MPa, wherein the duration is 15-20 s. And taking absolute ethyl alcohol as a solvent, and carrying out ultrasonic treatment on the matrix subjected to the sand blasting treatment for 5min to remove impurities. And soaking in absolute ethyl alcohol for 60min to remove greasy dirt, and drying in an oven at the temperature of 60 ℃ for 2h to prepare the coating.

2. Adhesive layer preparation by cold spraying and slurry dipping

(1) The cold spraying method comprises the steps of weighing according to the mass ratio of Mo to Si to binder=64:35:1, weighing according to the mass ratio of Mo to W to Si to binder=32:32:36:0.5, taking absolute ethyl alcohol as a solvent, taking zirconia balls as ball milling media, carrying out mixed ball milling at the ball milling speed of 500r/min for 4h, and preparing the Mo-Si or Mo-W-Si mixed solution. Preparing a bonding layer on the surface of a SiC _f/SiC matrix (silicon carbide ceramic matrix composite material matrix) by a cold spraying method, namely cold spraying a Mo-Si or Mo-W-Si mixed solution on the surface of the SiC _f/SiC matrix, drying in an oven in two steps, firstly drying at 60 ℃ for 24 hours, and then drying at 110 ℃ for 12 hours to prevent the coating from cracking, thereby preparing MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

(2) The slurry impregnation method comprises the steps of adopting a mechanical mixing ball milling and spray drying method to Mo and Si raw materials or Mo, W and Si raw materials (in the slurry impregnation method, weighing according to the mass ratio of Mo to Si to binder=64:35:1 or weighing according to the mass ratio of Mo to W to Si to binder=32:32:36:0.5), preparing Mo-Si or Mo-W-Si mixed powder, taking ethanol as a solvent, adding a certain mass of binder, preparing slurry, and stirring for 2-3 hours in a constant-temperature magnetic stirrer. Soaking the SiC _f/SiC matrix in the slurry, slowly extracting, putting into a drying oven, drying at 60 ℃ for 24h, drying at 110 ℃ for 12h, putting into an argon atmosphere furnace, and sintering at 1600 ℃ for 2h to obtain the MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

3. Preparation of composite coating

The preparation method comprises the steps of taking rare earth silicate as a main material, adding 10-20wt% of Si, adopting a mechanical mixing and spray granulation method to prepare Re ₂SiO₅ -Si composite powder with different rare earth elements, specifically, preparing Re ₂SiO₅ and Si powder into slurry through mechanical mixing and ball milling, carrying out spray granulation on the slurry to obtain Re ₂SiO₅ -Si composite powder, carrying out mixing and ball milling on Re ₂SiO₅ powder, si powder, deionized water, an Arabic gum binder and an ammonium citrate dispersing agent to obtain slurry, and drying the slurry in a spray drying mode to obtain spherical granulated powder with the particle size of 32-125 mu m. The self-healing environment barrier coating with the self-healing function is prepared by preparing a composite coating with the self-healing effect on the surface of a bonding layer through an atmospheric plasma spraying method, namely spraying Re ₂SiO₅ -Si composite powder on the surface of the bonding layer through the atmospheric plasma spraying method, wherein the atmospheric plasma preparation parameters are that the substrate temperature is preheated to 300-600 ℃ in the atmospheric plasma spraying process, the spray gun power is 20-42kW, the spraying distance is 100-200mm, the powder feeding rate is 3-10%, and the spraying angle is 30-60 ℃.

4. Test sample performance assessment:

(1) And (3) performing oxidation test, namely placing the self-healing environmental barrier coating sample at 1400 ℃ and 1500 ℃ respectively, performing static oxidation on the sample at each temperature for 2 hours, 16 hours, 32 hours and 64 hours, and observing the microscopic morphology of the coating and the substrate. Wherein, the oxidation test environment is two kinds of (1) static oxidation environment: atmospheric environment, and (2) water oxygen corrosion environment: 90% H ₂O-10％O₂.

(2) And (3) thermal shock testing, namely preserving the temperature of the sample at 1400 ℃ for 55min, cooling the sample in air for 5min, and respectively carrying out thermal shock for 16 times, 32 times and 64 times until the shedding area of the coating reaches 20% of the whole area, and stopping thermal shock.

(3) And (3) flame thermal cycle test, namely heating the sample for 5min by using the existing flame thermal cycle instrument, cooling for 2min, and respectively circulating for 200 times, 400 times and 800 times until the coating falling area reaches 20% of the whole area, and stopping the thermal cycle test.

The invention adopts MoSi ₂ or (Mo _x,W_1-x)Si₂ replaces the traditional Si coating as the bonding layer) with higher melting point, so that the coating can be used at 1600 ℃ and the oxidation resistance of the coating is improved.

According to the invention, moSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer) is prepared on the surface of the ceramic matrix composite material by adopting two different methods, namely a more convenient cold spraying method and a slurry dipping method, so that oxidation generated in the atmospheric plasma spraying process is avoided.

The Re ₂SiO₅ -Si powder (Re= Yb, Y, gd, lu, nd) is prepared by a spray granulation method, and the Re ₂SiO₅ -Si self-healing environment barrier coating is prepared on the surface of the bonding layer by adopting an atmospheric plasma method.

It should be noted that the above embodiments are merely for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solution described in the above embodiments may be modified or some or all of the technical features may be equivalently replaced, and these modifications or substitutions do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the present invention.

Claims

1. The preparation method of the self-healing environment barrier coating for the high-temperature oxidation resistance of the ceramic matrix composite material is characterized in that the coating is of a double-layer structure and sequentially comprises a bonding layer and a self-healing coating from inside to outside, wherein the bonding layer is prepared on the surface of the silicon carbide ceramic matrix composite material, and the self-healing coating is prepared on the surface of the bonding layer;

The material of the bonding layer is MoSi ₂ or (Mo _x,W_1-x)Si₂;

the ceramic matrix composite is a silicon carbide ceramic matrix composite;

the preparation method of the self-healing environment barrier coating for the ceramic matrix composite material, which is resistant to high-temperature oxidation, comprises the following steps:

S4, evaluating the performance of the sample, namely performing oxidation test, thermal shock test and flame thermal cycle test on the prepared self-healing environmental barrier coating sample;

The specific steps of the step S3 are as follows:

S31, taking rare earth silicate as a main material, adding 10-20wt% of Si, and preparing Re ₂SiO₅ -Si composite powder with different rare earth elements by adopting a mechanical mixing and spray granulation method;

S32, spraying Re ₂SiO₅ -Si composite powder on the surface of the bonding layer by an atmospheric plasma spraying method to prepare the self-healing coating, thereby preparing the self-healing environmental barrier coating with the self-healing function.

2. The method for preparing the self-healing environment barrier coating resistant to high temperature oxidation for the ceramic matrix composite material, which is disclosed in claim 1, is characterized in that the thickness of the bonding layer is 50-100 μm, the self-healing coating is 100-200 μm, and the size of the ceramic matrix composite material is 50 multiplied by 5mm ³.

3. The method for preparing the self-healing environment barrier coating for the ceramic matrix composite material, which is used for resisting high-temperature oxidation according to claim 1, is characterized in that in the step S1, a diamond grinding head is adopted to grind a silicon carbide ceramic matrix composite material into round corners, the surface of the ground silicon carbide ceramic matrix composite material is subjected to sand blasting treatment by using 220-mesh corundum particles under the pressure of 0.3 MPa for 15-20S, absolute ethyl alcohol is used as a solvent, ultrasonic treatment is carried out on the silicon carbide ceramic matrix composite material subjected to sand blasting treatment for 5min to remove impurities, then the silicon carbide ceramic matrix composite material is soaked in the absolute ethyl alcohol for 60 min to remove greasy dirt, and then the silicon carbide ceramic matrix composite material is dried in an oven at the temperature of between 60 ℃ for 2h for preparing the coating.

4. The method for preparing the self-healing environmental barrier coating resistant to high temperature oxidation for ceramic matrix composite materials according to claim 1, wherein in the step S2, the method for preparing the bonding layer by adopting a cold spraying method is as follows:

S21, weighing according to the mass ratio of Mo to Si in a binder=64:35:1 or weighing according to the mass ratio of Mo to W to Si in a binder=32:32:36:0.5, and performing ball milling by taking absolute ethyl alcohol as a solvent and zirconia balls as ball milling media at the ball milling speed of 500 r/min for 4: 4 h to obtain a Mo-Si or Mo-W-Si mixed solution;

s22, performing cold spraying on the surface of the silicon carbide ceramic matrix composite material by using a cold spraying method, then performing two-step drying in an oven, firstly drying at 60 ℃ for 24 h, and then drying at 110 ℃ for 12 h to prepare MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

5. The method for preparing a self-healing environmental barrier coating for ceramic matrix composites, according to claim 4, wherein the MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer) prepared in step S22 is solid phase sintered for 2 hours at 1500 ℃ in a hot press furnace under argon atmosphere to better bond the coating with the silicon carbide ceramic matrix composite substrate, and the process is repeated for a plurality of times to obtain a thickness of 50-100 μm.

6. The method for preparing the self-healing environment barrier coating resistant to high temperature oxidation for ceramic matrix composite materials according to claim 1, wherein in the step S2, a bonding layer method by adopting a slurry impregnation method is as follows:

S202, dipping a silicon carbide ceramic matrix composite material matrix into slurry, slowly putting the slurry into a drying oven, drying the slurry at a temperature of 60 ℃ for 24 h ℃ and then drying the slurry at a temperature of 110 ℃ for 12 h, putting the slurry into an argon atmosphere furnace for high-temperature sintering, and sintering at a temperature of 1600 ℃ for 2 h to prepare MoSi ₂ or (Mo _x,W_1-x)Si₂ bonding layer).

7. The method for preparing the self-healing environmental barrier coating for ceramic matrix composite materials, which is resistant to high temperature oxidation according to claim 1, wherein in the step S4, the oxidation test specifically comprises the steps of placing the self-healing environmental barrier coating sample at 1400 ℃ and 1500 ℃ respectively, carrying out static oxidation on the sample at each temperature for 2h, 16 h, 32 h and 64 h, and observing the microscopic morphology of the coating and the matrix;

The thermal shock test specifically comprises the following steps of preserving the temperature of a sample at 1400 ℃ for 55 min times, cooling the sample with air for 5 min times, and respectively carrying out thermal shock for 16 times, 32 times and 64 times until the shedding area of the coating reaches 20% of the whole area, and stopping thermal shock;