High-temperature anti-oxidation coating on surface of ceramic-based composite material and preparation method of high-temperature anti-oxidation coating

Abstract

The preparation method comprises the following steps: sequentially spraying a base layer consisting of silicon powder, a composite layer consisting of mullite powder and strontium-doped barium feldspar powder in a specific content ratio, and a surface layer consisting of the strontium-doped barium feldspar powder on the surface of the ceramic-based composite material, thereby obtaining the high-temperature oxidation-resistant coating on the surface of the ceramic-based composite material. A high-temperature anti-oxidation coating is formed on the surface of the ceramic-based composite material, so that the oxidation resistance and the fatigue performance of the ceramic-based composite material under a high-temperature oxidation condition are improved; meanwhile, a compact oxide layer is formed on the surface of the base material, so that the adhesion of the base material to the base layer is enhanced, the bonding strength of the ceramic-based composite material base material is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present application relates to the technical field of high-temperature anti-oxidation coatings in aerospace boosters, and in particular to a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material and a preparation method thereof. Background Art

[0002] Ceramic-based composites, including Cf / SiC and SiCf / SiC, are composites with SiC ceramic as the matrix and C or SiC fiber reinforcement. Ceramic-based composites have the characteristics of low density, high temperature resistance, excellent mechanical properties, and oxidation resistance, and are expected to be candidate materials to replace high-temperature alloys. In the working environment of aerospace boosters, service materials not only need to withstand high temperatures of around 1400°C, but also need to cope with the combined effects of high loads, corrosive environments, and thermomechanical stresses. Although ceramic-based composites have high-temperature resistance to a certain extent, they are prone to oxidation, wear, or thermal fatigue aging during long-term service, resulting in a sharp decline in the quality and performance of ceramic-based composites, affecting the overall reliability and life of the boosters, and increasing maintenance frequency and costs.

[0003] In view of this, there is an urgent need to propose a high-temperature anti-oxidation coating and a preparation method thereof for improving the performance and quality of ceramic-based composite materials. Summary of the invention

[0004] The purpose of the present invention is to provide a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material and a preparation method thereof, so as to enhance the reliability and life of aerospace boosters during service and solve the problems of poor quality and performance existing in the prior art.

[0005] In order to solve the above technical problems, the present invention adopts the following solutions:

[0006] A high-temperature anti-oxidation coating on the surface of a ceramic-based composite material, comprising a base layer, a composite layer and a surface layer sequentially prepared on the surface of the ceramic-based composite material, wherein the base layer is silicon, the composite layer is mullite and strontium-doped baryte, and the surface layer is strontium-doped baryte;

[0007] In the bottom layer of the composite layer, the mass percentage of mullite is 70% to 90%, and the mass percentage of strontium-doped barium feldspar is 10% to 30%;

[0008] In the top layer of the composite layer, the mass percentage of mullite is 10% to 30%, and the mass percentage of strontium-doped barium feldspar is 70% to 90%;

[0009] The middle layer of the composite layer includes a plurality of sub-layers. From the bottom layer to the middle layer and the top layer of the composite layer, the content of mullite decreases layer by layer, and the content of strontium-doped barium feldspar increases layer by layer.

[0010] Furthermore, the thickness of the base layer is 100 μm, the thickness of the composite layer is 100-200 μm, and the thickness of the surface layer is 100 μm.

[0011] Furthermore, the number of the intermediate layers is 2 to 5, and the thickness of each layer is 20 to 40 μm.

[0012] Furthermore, in the composite layer, the difference in mass percentage of mullite in adjacent layers is 10% to 15%, and the difference in mass percentage of strontium-doped barium feldspar in adjacent layers is 10% to 15%.

[0013] A method for preparing the high temperature anti-oxidation coating on the surface of the above-mentioned ceramic-based composite material comprises the following steps:

[0014] S1, substrate pretreatment: removing impurities and oil stains on the surface of the ceramic matrix composite material, and preparing a continuous dense oxide layer on the surface to obtain a pretreated substrate;

[0015] S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence;

[0016] The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar.

[0017] Furthermore, in step S1, the substrate is placed at a temperature of 1500° C. to 1700° C. in a high-purity oxygen atmosphere to form a continuous dense oxide layer on the surface of the substrate. The main purpose of forming a continuous dense oxide layer on the surface of the ceramic matrix composite material is to enhance the adhesion of the silicon powder in the sprayed base layer to the base layer, thereby increasing the bonding strength of the ceramic matrix composite material substrate.

[0018] Furthermore, during spraying, silicon powder, mullite powder and strontium-doped barium feldspar powder with a powder particle size of 100-200 meshes and a purity of 99% are used.

[0019] Furthermore, when spraying the base layer, the total amount of plasma gas is 150-180 lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 5-8 slpm; the spraying distance is 150-200 mm; and the powder feeding rate is 80-130 g / min.

[0020] Furthermore, when spraying the composite layer, the total plasma gas volume is 100-180 lpm, of which the volume of nitrogen accounts for 60% and the volume of hydrogen accounts for 40%; the carrier gas flow rate is 5-8 slpm; the spraying distance is 150-200 mm; and the powder feeding rate is 80-100 g / min.

[0021] Furthermore, when spraying the surface layer, the total plasma gas volume is 150-180 lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 5-8 slpm; the spraying distance is 150-200 mm; and the powder feeding rate is 80-100 g / min.

[0022] The beneficial effects of the present invention are as follows: the present invention sequentially sprays a base layer composed of silicon powder, a composite layer composed of mullite powder and strontium-doped barium feldspar powder with a specific content ratio, and a surface layer composed of strontium-doped barium feldspar powder on the surface of the ceramic-based composite material, thereby forming a high-temperature anti-oxidation coating on the surface of the ceramic-based composite material, improving the anti-oxidation performance and fatigue performance of the ceramic-based composite material under high-temperature oxidation conditions; at the same time, a continuous dense oxide layer is formed on the surface of the substrate, enhancing the adhesion of the substrate to the base layer, thereby increasing the bonding strength of the ceramic-based composite material substrate and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the structure of the high temperature anti-oxidation coating in the present invention.

[0024] Figure numerals: 1-ceramic-based composite material substrate, 2-base layer, 3-composite layer, 30-bottom layer, 31-middle layer, 32-top layer, 4-surface layer. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0027] Technologies, methods, and apparatus known to ordinary technicians in the relevant field may not be discussed in detail, but where appropriate, such technologies, methods, and apparatus should be considered part of the authorization specification.

[0028] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0029] Example 1

[0030] A high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises a base layer, a composite layer and a surface layer. The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar. The purity of silicon powder, mullite powder and strontium-doped barium feldspar powder used in spraying is 99%, and the powder particle size is 100-200 meshes.

[0031] A method for preparing a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises the following steps:

[0032] S1, substrate pretreatment: acetone or alcohol is used to remove impurities and oil stains on the surface of the ceramic-based composite material. After ensuring drying, the substrate is placed at a temperature of 1500°C to 1700°C in a high-purity oxygen atmosphere (volume fraction ≥ 99%) to form a continuous dense oxide layer on the surface of the substrate, and a continuous dense oxide layer is prepared on the surface to obtain a pretreated substrate.

[0033] S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence.

[0034] When spraying silicon powder on the base layer, the total volume of plasma gas is 150lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 8slpm; the spraying distance is 150mm; the powder feeding rate is 80g / min, and the spraying is stopped when the thickness reaches 100μm.

[0035] When spraying the composite layer, spray the bottom layer, middle layer and top layer in sequence. The bottom layer is 70% mullite powder and 30% strontium-doped barium feldspar powder; the middle layer is 60% mullite powder + 40% strontium-doped barium feldspar powder, 50% mullite powder + 50% strontium-doped barium feldspar powder, 40% mullite powder + 60% strontium-doped barium feldspar powder from bottom to top; the top layer is 30% mullite powder + 70% strontium-doped barium feldspar powder; the total plasma gas volume is 120lpm, of which nitrogen accounts for 60% by volume and hydrogen accounts for 40% by volume; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, and the thickness of each layer is 35μm, that is, the total thickness of the composite layer is 175μm, then stop spraying. Figure 1 shown.

[0036] When spraying the surface layer of strontium-doped barium feldspar powder, the total plasma gas volume is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, and the spraying is stopped when the thickness reaches 100μm.

[0037] The ceramic-based composite materials sprayed with high-temperature anti-oxidation coating were subjected to a quasi-static test in a static water-oxygen coupling environment. The samples were placed in a simulation device and heated to 1400°C with the furnace. The weight of the samples was monitored regularly and the time for the samples to peel off was recorded until the test time reached 300 hours.

[0038] The test results are: the coating structure is intact, no cracking or peeling occurs, and the strength retention rate of the sample is 110%.

[0039] Example 2

[0040] A high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises a base layer, a composite layer and a surface layer. The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar. The purity of silicon powder, mullite powder and strontium-doped barium feldspar powder used in spraying is 99%, and the powder particle size is 100-200 meshes.

[0041] A method for preparing a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises the following steps:

[0042] S1, substrate pretreatment: acetone or alcohol is used to remove impurities and oil stains on the surface of the ceramic-based composite material. After ensuring drying, the substrate is placed at a temperature of 1500°C to 1700°C in a high-purity oxygen atmosphere (volume fraction ≥ 99%) to form a continuous dense oxide layer on the surface of the substrate, and a continuous dense oxide layer is prepared on the surface to obtain a pretreated substrate.

[0043] S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence.

[0044] When spraying silicon powder on the base layer, the total volume of plasma gas is 160lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 8slpm; the spraying distance is 150mm; the powder feeding rate is 80g / min, and the spraying is stopped when the thickness reaches 100μm.

[0045] When spraying the composite layer, the bottom layer, the middle layer and the top layer are sprayed in sequence, the bottom layer is 80% mullite powder and 20% strontium-doped barium feldspar powder; the middle layer is 70% mullite powder + 30% strontium-doped barium feldspar powder, 60% mullite powder + 40% strontium-doped barium feldspar powder, 50% mullite powder + 50% strontium-doped barium feldspar powder, 40% mullite powder + 60% strontium-doped barium feldspar powder from bottom to top; the top layer is 30% mullite powder + 70% strontium-doped barium feldspar powder; the total gas volume of plasma gas is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, the thickness of each layer is 30μm, that is, the total thickness of the composite layer is 180μm and the spraying is stopped.

[0046] When spraying the surface layer of strontium-doped barium feldspar powder, the total plasma gas volume is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, and the spraying is stopped when the thickness reaches 100μm.

[0047] The ceramic-based composite materials sprayed with high-temperature anti-oxidation coating were subjected to a quasi-static test in a static water-oxygen coupling environment. The samples were placed in a simulation device and heated to 1400°C with the furnace. The weight of the samples was monitored regularly and the time for the samples to peel off was recorded until the test time reached 300 hours.

[0048] The test results are: the coating structure is intact, no cracking or peeling occurs, and the strength retention rate of the sample is 108%.

[0049] Example 3

[0050] A high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises a base layer, a composite layer and a surface layer. The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar. The purity of silicon powder, mullite powder and strontium-doped barium feldspar powder used in spraying is 99%, and the powder particle size is 100-200 meshes.

[0051] A method for preparing a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises the following steps:

[0052] S1, substrate pretreatment: acetone or alcohol is used to remove impurities and oil stains on the surface of the ceramic-based composite material. After ensuring drying, the substrate is placed at a temperature of 1500°C to 1700°C in a high-purity oxygen atmosphere (volume fraction ≥ 99%) to form a continuous dense oxide layer on the surface of the substrate, and a continuous dense oxide layer is prepared on the surface to obtain a pretreated substrate.

[0053] S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence.

[0054] When spraying silicon powder on the base layer, the total volume of plasma gas is 160lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 8slpm; the spraying distance is 150mm; the powder feeding rate is 80g / min, and the spraying is stopped when the thickness reaches 100μm.

[0055] When spraying the composite layer, the bottom layer, the middle layer and the top layer are sprayed in sequence, the bottom layer is 90% mullite powder and 10% strontium-doped barium feldspar powder; the middle layer is 75% mullite powder + 25% strontium-doped barium feldspar powder, 60% mullite powder + 40% strontium-doped barium feldspar powder, 45% mullite powder + 55% strontium-doped barium feldspar powder from bottom to top; the top layer is 30% mullite powder + 70% strontium-doped barium feldspar powder; the total gas volume of plasma gas is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, the thickness of each layer is 40μm, that is, the total thickness of the composite layer is 200μm and the spraying is stopped.

[0056] When spraying the surface layer of strontium-doped barium feldspar powder, the total plasma gas volume is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, and the spraying is stopped when the thickness reaches 100μm.

[0057] The ceramic-based composite materials sprayed with high-temperature anti-oxidation coating were subjected to a quasi-static test in a static water-oxygen coupling environment. The samples were placed in a simulation device and heated to 1400°C with the furnace. The weight of the samples was monitored regularly and the time for the samples to peel off was recorded until the test time reached 300 hours.

[0058] The test results are: the coating structure is intact, no cracking or peeling occurs, and the strength retention rate of the sample is 105%.

[0059] Example 4

[0060] A high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises a base layer, a composite layer and a surface layer. The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar. The purity of silicon powder, mullite powder and strontium-doped barium feldspar powder used in spraying is 99%, and the powder particle size is 100-200 meshes.

[0061] A method for preparing a high-temperature anti-oxidation coating on the surface of a ceramic-based composite material comprises the following steps:

[0062] S1, substrate pretreatment: acetone or alcohol is used to remove impurities and oil stains on the surface of the ceramic-based composite material. After ensuring drying, the substrate is placed at a temperature of 1500°C to 1700°C in a high-purity oxygen atmosphere (volume fraction ≥ 99%) to form a continuous dense oxide layer on the surface of the substrate, and a continuous dense oxide layer is prepared on the surface to obtain a pretreated substrate.

[0063] S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence.

[0064] When spraying silicon powder on the base layer, the total plasma gas volume is 180lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 8slpm; the spraying distance is 150mm; the powder feeding rate is 90g / min, and the spraying is stopped when the thickness reaches 100μm.

[0065] When spraying the composite layer, the bottom layer, the middle layer and the top layer are sprayed in sequence, the bottom layer is 80% mullite powder and 20% strontium-doped barium feldspar powder; the middle layer is 70% mullite powder + 30% strontium-doped barium feldspar powder, 55% mullite powder + 45% strontium-doped barium feldspar powder, 40% mullite powder + 60% strontium-doped barium feldspar powder, 30% mullite powder + 70% strontium-doped barium feldspar powder from bottom to top; the top layer is 15% mullite powder + 85% strontium-doped barium feldspar powder; the total gas volume of plasma gas is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, the thickness of each layer is 30μm, that is, the total thickness of the composite layer is 180μm and the spraying is stopped.

[0066] When spraying the surface layer of strontium-doped barium feldspar powder, the total plasma gas volume is 120lpm, of which the volume proportion of nitrogen is 60% and the volume proportion of hydrogen is 40%; the carrier gas flow rate is 6slpm; the spraying distance is 180mm; the powder feeding rate is 90g / min, and the spraying is stopped when the thickness reaches 100μm.

[0067] The ceramic-based composite materials sprayed with high-temperature anti-oxidation coating were subjected to a quasi-static test in a static water-oxygen coupling environment. The samples were placed in a simulation device and heated to 1400°C with the furnace. The weight of the samples was monitored regularly under 120MPa conditions, and the time for the samples to peel off was recorded until the test time reached 300 hours.

[0068] The test results are: the coating structure is intact, no cracking or peeling occurs, and the strength retention rate of the sample is 110%.

[0069] Comparative Example 1

[0070] The difference between Comparative Example 1 and Example 1 is that the composite layer is a sprayed layer of 70% mullite powder + 30% strontium-doped barium feldspar powder.

[0071] Comparative Example 2

[0072] The difference between this comparative example 2 and example 1 is that the composite layer is sprayed with two layers of 80% mullite powder + 20% strontium-doped barium feldspar powder (bottom layer) and 10% mullite powder + 90% strontium-doped barium feldspar powder (surface layer).

[0073] The ceramic-based composite materials sprayed with high-temperature anti-oxidation coating in Comparative Example 1 and Comparative Example 2 were respectively subjected to a static water-oxygen coupling environment quasi-static test. The samples were placed in a simulation device and heated to 1400°C with the furnace. The sample weight was regularly monitored and the time for sample peeling was recorded until the test time reached 300 hours.

[0074] The test results are as follows: the coating structure of comparative example 1 is incomplete, the surface layer falls off, the middle layer and the top layer of the composite layer are partially cracked, and the strength retention rate of the sample is 76%.

[0075] The coating structure of Comparative Example 2 is incomplete, the surface layer falls off, the top layer of the composite layer falls off, the middle layer and the bottom layer are partially cracked, and the strength retention rate of the sample is 70%.

[0076] The above description is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A high temperature anti-oxidation coating on the surface of a ceramic matrix composite material, characterized in that: The method comprises preparing a base layer, a composite layer and a surface layer on the surface of a ceramic-based composite material in sequence, wherein the base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar; In the bottom layer of the composite layer, the mass percentage of mullite is 70% to 90%, and the mass percentage of strontium-doped barium feldspar is 10% to 30%; In the top layer of the composite layer, the mass percentage of mullite is 10% to 30%, and the mass percentage of strontium-doped barium feldspar is 70% to 90%; The middle layer of the composite layer includes a plurality of sub-layers. From the bottom layer to the middle layer and the top layer of the composite layer, the content of mullite decreases layer by layer, and the content of strontium-doped barium feldspar increases layer by layer.

2. The high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 1, characterized in that: The thickness of the base layer is 100 μm, the thickness of the composite layer is 100-200 μm, and the thickness of the surface layer is 100 μm.

3. The high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 1, characterized in that: The number of the intermediate layers is 2 to 5, and the thickness of each layer is 20 to 40 μm.

4. The high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 1, characterized in that: In the composite layer, the difference in mass percentage of mullite in adjacent layers is 10% to 15%, and the difference in mass percentage of strontium-doped barium feldspar in adjacent layers is 10% to 15%.

5. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, substrate pretreatment: removing impurities and oil stains on the surface of the ceramic matrix composite material, and preparing a continuous dense oxide layer on the surface to obtain a pretreated substrate; S2, preparing a high temperature anti-oxidation coating: using plasma spraying technology to spray a base layer, a composite layer and a surface layer on the surface of the pretreated substrate in sequence; The base layer is silicon, the composite layer is mullite and strontium-doped barium feldspar, and the surface layer is strontium-doped barium feldspar.

6. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 5, characterized in that: In step S1, the substrate is placed at a temperature of 1500° C. to 1700° C. in a high-purity oxygen atmosphere to form a dense oxide layer on the surface of the substrate.

7. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 5, characterized in that: During spraying, silicon powder, mullite powder and strontium-doped barium feldspar powder with a particle size of 100-200 meshes and a purity of 99% are used.

8. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 7, characterized in that: When spraying the base layer, the total volume of plasma gas is 150-180 lpm, of which the volume of nitrogen accounts for 60%, the volume of hydrogen accounts for 20%, and the volume of argon accounts for 20%; the carrier gas flow rate is 5-8 slpm; the spraying distance is 150-200 mm; and the powder feeding rate is 80-130 g / min.

9. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 7, characterized in that: When spraying the composite layer, the total plasma gas volume is 100-180 lpm, of which the volume of nitrogen accounts for 60% and the volume of hydrogen accounts for 40%; the carrier gas flow rate is 5-8 slpm; the spraying distance is 150-200 mm; and the powder feeding rate is 80-100 g / min.

10. The method for preparing a high temperature anti-oxidation coating on the surface of a ceramic matrix composite material according to claim 7, characterized in that: When spraying the surface layer, the total plasma gas volume is 150-180lpm, of which the volume of nitrogen accounts for 60% and the volume of hydrogen accounts for 40%; the carrier gas flow rate is 5-8slpm; the spraying distance is 150-200mm; and the powder feeding rate is 80-100g / min.

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