Preparation method of aerobic high-temperature-resistant C / SiC sealing strip modified by sol-gel method

Abstract

The invention discloses a preparation method of an aerobic high-temperature-resistant C / SiC sealing strip modified by a sol-gel method, and relates to a preparation method of a C / SiC sealing strip. The invention aims to solve the problem of insufficient aerobic high-temperature resistance of the existing C / SiC sealing strip. The method comprises the following steps: 1, low-temperature plasma treatment; 2, a CVD deposition process; 3, preparing a silicon dioxide anti-oxidation layer by a sol-gel method; and 4, post-processing. The method is used for preparing the aerobic high-temperature-resistant C / SiC sealing strip modified by the sol-gel method.

Description

Technical Field

[0001] The present invention relates to a preparation method of a C / SiC sealing strip. Background Art

[0002] In the fields of aerospace, automotive engines, high-temperature industrial furnaces, etc., the sealing strip needs to work stably for a long time in an oxygen-rich and high-temperature environment to ensure the sealing and safety of the equipment. Due to its high strength, high hardness, good wear resistance and high temperature resistance, C / SiC composite material has become an ideal material for preparing high-performance sealing strips. Currently, depositing SiC particles on the surface of the carbon fiber sealing strip by CVD is a commonly used strengthening method, which can effectively improve the basic performance of the sealing strip. However, in an oxygen-rich high-temperature environment, oxygen will chemically react with the C / SiC material, resulting in material oxidation and structural damage, and then reducing the sealing performance of the sealing strip and shortening its service life. Therefore, it is of great practical significance to develop a simple and efficient method to improve the oxygen-rich high-temperature resistance of the C / SiC sealing strip. Summary of the Invention

[0003] The present invention aims to solve the problem of insufficient oxygen-rich high-temperature resistance of the existing C / SiC sealing strip, and further provides a preparation method of an oxygen-rich high-temperature resistant C / SiC sealing strip modified by the sol-gel method.

[0004] A preparation method of an oxygen-rich high-temperature resistant C / SiC sealing strip modified by the sol-gel method is carried out according to the following steps:

[0005] I. Low-temperature plasma treatment:

[0006] Using argon as the working gas, under the conditions of an argon flow rate of 50 sccm to 450 sccm and a radio frequency power of 20 W to 150 W, the carbon fiber sealing strip is subjected to low-temperature plasma treatment for 5 min to 100 min to obtain a plasma-treated carbon fiber sealing strip;

[0007] II. CVD deposition process:

[0008] The plasma-treated carbon fiber sealing strip is placed in the reaction chamber of the CVD reaction equipment and evacuated, then a mixed reaction gas is introduced, and at the same time, the heating system is turned on. The reaction chamber is heated to 1050 °C to 1550 °C at a heating rate of 10 °C / min to 15 °C / min. Then, under the conditions of a sample rotation speed of 15 r / min to 100 r / min, a reaction chamber pressure of 1 Pa to 40 Pa, and a temperature of 1050 °C to 1550 °C, the deposition reaction is carried out for 1 h to 10 h. After the deposition is completed, the introduction of the mixed reaction gas is stopped, and the vacuum state is maintained to allow the reaction chamber to cool naturally to room temperature. Finally, it is taken out to obtain a CVD-deposited carbon fiber sealing strip;

[0009] The described mixed reaction gas is composed of a silicon source gas, a carbon source gas, and a dilution gas;

[0010] III. Preparation of a silica antioxidant layer by sol-gel method:

[0011] Tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid solution are stirred and mixed evenly to obtain a transparent sol. Then, the carbon fiber sealing strip after CVD deposition is immersed in the transparent sol, and the dipping and pulling method is used to pull the sealing strip at a uniform pulling speed of 2 mm / s to 5 mm / s, so that the sol adheres evenly to the surface of the sealing strip. Then, a gelling reaction is carried out to form a silica gel layer. Finally, under the conditions of an argon atmosphere and a temperature of 500 °C to 1000 °C, heat preservation is carried out for 1 h to 2 h to obtain a C / SiC sealing strip coated with a silica antioxidant layer;

[0012] IV. Post-treatment:

[0013] The C / SiC sealing strip coated with a silica antioxidant layer is successively subjected to grinding and polishing treatments, and then low-temperature annealing treatment, that is, the preparation method of the aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method is completed.

[0014] The beneficial effects of the present invention are:

[0015] An aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method provided by the present invention is an improvement on the basis of the existing preparation method of CVD silicon carbide coating. Using this method can significantly enhance the overall structural stability, improve the aerobic high-temperature resistance performance of the sealing strip, and at the same time maintain the relative simplicity of the preparation process and cost controllability. This sealing strip can be used in the field of high-temperature resistant sealing. Description of the drawings

[0016] Figure 1 It is a comparison chart of the oxidation weight gain rates of the aerobic high-temperature resistant C / SiC sealing strips prepared in Examples 1-2 and Comparative Example 1 under the high-temperature condition of 800 °C;

[0017] Figure 2 It is a comparison chart of the time for maintaining good sealing performance of the aerobic high-temperature resistant C / SiC sealing strips prepared in Examples 1-2 and Comparative Example 1 under the high-temperature condition of 800 °C. Detailed implementation manners

[0018] Detailed implementation manner one: A preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method in this implementation manner is carried out according to the following steps:

[0019] I. Low-temperature plasma treatment:

[0020] Using argon as the working gas, under the conditions of an argon flow rate of 50 sccm to 450 sccm and a radio frequency power of 20 W to 150 W, the carbon fiber sealing strip is subjected to low-temperature plasma treatment for 5 min to 100 min to obtain a carbon fiber sealing strip after plasma treatment;

[0021] II. CVD deposition process:

[0022] The carbon fiber sealing strip after plasma treatment is placed in the reaction chamber of the CVD reaction equipment and evacuated, and then a mixed reaction gas is introduced. At the same time, the heating system is turned on, and the reaction chamber is heated to 1050 °C to 1550 °C at a heating rate of 10 °C / min to 15 °C / min. Then, under the conditions of a sample rotation speed of 15 r / min to 100 r / min, a reaction chamber pressure of 1 Pa to 40 Pa, and a temperature of 1050 °C to 1550 °C, the deposition reaction is carried out for 1 h to 10 h. After the deposition is completed, the introduction of the mixed reaction gas is stopped, and the vacuum state is maintained to allow the reaction chamber to cool naturally to room temperature. Finally, it is taken out to obtain a carbon fiber sealing strip after CVD deposition;

[0023] The mixed reaction gas is composed of a silicon source gas, a carbon source gas, and a dilution gas;

[0024] III. Preparation of a silica antioxidant layer by sol-gel method:

[0025] Tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid solution are stirred and mixed evenly to obtain a transparent sol. Then, the carbon fiber sealing strip after CVD deposition is immersed in the transparent sol, and the dipping and pulling method is used to pull the sealing strip at a uniform pulling speed of 2 mm / s to 5 mm / s to make the sol adhere evenly to the surface of the sealing strip. Then, a gelation reaction is carried out to form a silica gel layer. Finally, under the conditions of an argon atmosphere and a temperature of 500 °C to 1000 °C, it is kept warm for 1 h to 2 h to obtain a C / SiC sealing strip coated with a silica antioxidant layer;

[0026] IV. Post-treatment:

[0027] The C / SiC sealing strip coated with a silica antioxidant layer is successively subjected to grinding and polishing treatments, and then low-temperature annealing treatment, thus completing the preparation method of the oxygen-resistant high-temperature C / SiC sealing strip modified by the sol-gel method.

[0028] In step one of this specific embodiment, the low-temperature plasma treatment increases the surface roughness and active sites, improving the adhesion of the subsequent coating.

[0029] In step two of this specific embodiment, during the deposition process, the reaction chamber pressure is maintained at 1 Pa to 40 Pa, enabling the uniform deposition of SiC particles on the surface of the sealing strip.

[0030] In the second step of this specific embodiment, the sol undergoes a gelation reaction to form a silica gel layer.

[0031] In the second step of this specific embodiment, the silica gel layer is transformed into a dense silica antioxidant layer by heat preservation at 500°C to 1000°C.

[0032] In the third step of this specific embodiment, grinding and polishing treatments are performed to remove the uneven parts on the surface, so that the dimensional accuracy and surface quality of the sealing strip meet the usage requirements.

[0033] In the third step of this specific embodiment, low-temperature annealing treatment is carried out to eliminate internal residual stress and improve the performance stability of the material.

[0034] The beneficial effects of this embodiment are as follows:

[0035] A kind of aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method provided by this embodiment is an improvement on the basis of the existing preparation method of CVD silicon carbide coating. Using this method can significantly enhance the overall structural stability, improve the aerobic high-temperature resistant performance of the sealing strip, and at the same time maintain the relative simplicity of the preparation process and cost controllability. This sealing strip can be used in the field of high-temperature resistant sealing.

[0036] Specific embodiment two: The difference between this embodiment and specific embodiment one is that: the carbon fiber sealing strip described in step one is a pretreated carbon fiber sealing strip, and the pretreatment is specifically carried out according to the following steps: under the condition of an ultrasonic power of 300W to 500W, it is successively placed in acetone and absolute ethanol for ultrasonic cleaning for 15min to 120min respectively, and then dried for 1h to 10h under the condition of a temperature of 60°C to 180°C. Others are the same as specific embodiment one.

[0037] This specific embodiment removes oil stains, impurities, mold release agents, etc. on the surface through cleaning.

[0038] Specific embodiment three: The difference between this embodiment and one of specific embodiments one or two is that: the carbon fiber sealing strip described in step one is woven from T300 carbon fiber bundles. Others are the same as specific embodiment one or two.

[0039] Specific embodiment four: The difference between this embodiment and one of specific embodiments one to three is that: the silicon source gas described in step two is SiH4; the carbon source gas described in step two is CH4; the dilution gas described in step two is hydrogen. Others are the same as specific embodiment three.

[0040] Specific embodiment five: The difference between this embodiment and one of specific embodiments one to four is that: the purity of the silicon source gas, carbon source gas, and dilution gas described in step two is all ≥4N. Others are the same as specific embodiments one to four.

[0041] Embodiment Six: The difference between this embodiment and any one of Embodiments One to Five is as follows: in Step 2, the volume ratio of the silicon source gas to the carbon source gas is 1:(1-5); in Step 2, the volume ratio of the silicon source gas to the dilution gas is 1:(1-20). Others are the same as those in Embodiments One to Five.

[0042] Embodiment Seven: The difference between this embodiment and any one of Embodiments One to Six is as follows: in Step 2, evacuate to 10 -4 Pa to 10 -2 Pa. Others are the same as those in Embodiments One to Six.

[0043] Embodiment Eight: The difference between this embodiment and any one of Embodiments One to Seven is as follows: in Step 3, the molar ratio of tetraethyl orthosilicate to absolute ethanol is 1:(4-6); in Step 3, the molar ratio of tetraethyl orthosilicate to deionized water is 1:(2-4); in Step 3, the molar ratio of tetraethyl orthosilicate to hydrochloric acid in the hydrochloric acid solution is 1:(0.01-0.03); the mass percentage of the hydrochloric acid solution in Step 3 is 2%-20%; the purities of tetraethyl orthosilicate and absolute ethanol in Step 3 are both ≥4N. Others are the same as those in Embodiments One to Seven.

[0044] Embodiment Nine: The difference between this embodiment and any one of Embodiments One to Eight is as follows: in Step 3, under the condition that the stirring speed is 300 r / min - 500 r / min, stir and mix tetraethyl orthosilicate, absolute ethanol, deionized water and the hydrochloric acid solution for 1 h - 2 h; the gelling reaction in Step 3 is specifically carried out under the condition that the temperature is 60 °C - 100 °C for 1 h - 2 h; in Step 3, under the argon protection atmosphere, heat up to 500 °C - 1000 °C at a heating rate of 5 °C / min - 10 °C / min. Others are the same as those in Embodiments One to Eight.

[0045] Embodiment Ten: The difference between this embodiment and any one of Embodiments One to Nine is as follows: the low-temperature annealing treatment in Step 4 is specifically carried out under the argon atmosphere and at a temperature of 300 °C - 800 °C for 1 h - 10 h. Others are the same as those in Embodiments One to Nine.

[0046] The following examples are used to verify the beneficial effects of the present invention:

[0047] Example 1:

[0048] A preparation method of an oxygen-resistant high-temperature-resistant C / SiC sealing strip modified by the sol-gel method, which is carried out according to the following steps:

[0049] I. Low-temperature plasma treatment:

[0050] Using argon as the working gas, the carbon fiber sealing strip was treated by low-temperature plasma for 8 minutes under the conditions of an argon flow rate of 60 sccm and a radio frequency power of 120 W to obtain the plasma-treated carbon fiber sealing strip;

[0051] II. CVD deposition process:

[0052] The plasma-treated carbon fiber sealing strip was placed in the reaction chamber of the CVD reaction equipment, evacuated to 5×10 -3 Pa, and then the mixed reaction gas was introduced. At the same time, the heating system was turned on, and the reaction chamber was heated to 1100 °C at a heating rate of 12 °C / min. Then, under the conditions of a sample rotation speed of 50 r / min, a reaction chamber pressure of 30 Pa, and a temperature of 1100 °C, the deposition reaction was carried out for 4 h. After the deposition was completed, the introduction of the mixed reaction gas was stopped, and the vacuum state was maintained to allow the reaction chamber to cool naturally to room temperature. Finally, it was taken out to obtain the carbon fiber sealing strip after CVD deposition;

[0053] The mixed reaction gas is composed of a silicon source gas, a carbon source gas, and a dilution gas;

[0054] The silicon source gas is SiH4; the carbon source gas is CH4; the dilution gas is hydrogen;

[0055] The purities of the silicon source gas, the carbon source gas, and the dilution gas are all ≥4N;

[0056] The volume ratio of the silicon source gas to the carbon source gas is 1:2.5; the volume ratio of the silicon source gas to the dilution gas is 1:18;

[0057] III. Preparation of silica antioxidant layer by sol-gel method:

[0058] Under the condition of a stirring speed of 400 r / min, tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid solution were stirred and mixed for 1.5 h to obtain a transparent sol. Then, the carbon fiber sealing strip after CVD deposition was immersed in the transparent sol, and the dipping and pulling method was used to pull the sealing strip at a uniform pulling speed of 3 mm / s to make the sol uniformly adhere to the surface of the sealing strip. Then, under the condition of a temperature of 70 °C, a gelling reaction was carried out for 1.5 h to form a silica gel layer. Finally, under an argon protection atmosphere, it was heated to 550 °C at a heating rate of 8 °C / min and kept at 550 °C under an argon atmosphere for 1.5 h to obtain the C / SiC sealing strip coated with a silica antioxidant layer;

[0059] The molar ratio of tetraethyl orthosilicate to absolute ethanol is 1:5; the molar ratio of tetraethyl orthosilicate to deionized water is 1:3; the molar ratio of tetraethyl orthosilicate to hydrochloric acid in the hydrochloric acid solution is 1:0.02; the mass percentage of the hydrochloric acid solution is 5%; the purity of both tetraethyl orthosilicate and absolute ethanol is ≥4N;

[0060] IV. Post-treatment:

[0061] The C / SiC sealing strip coated with a silica antioxidant layer is successively polished and buffed, and then under the conditions of an argon atmosphere and a temperature of 350 °C, it is subjected to low-temperature annealing treatment for 1.5 h to obtain an oxygen-containing high-temperature resistant C / SiC sealing strip.

[0062] The carbon fiber sealing strip described in Step I is a pretreated carbon fiber sealing strip, and the pretreatment is specifically carried out according to the following steps: Under the condition of an ultrasonic power of 400 W, it is successively placed in acetone and absolute ethanol for ultrasonic cleaning for 18 min respectively, and then under the condition of a temperature of 70 °C, it is dried for 2.5 h.

[0063] The carbon fiber sealing strip described in Step I is woven from T300 carbon fiber bundles.

[0064] Example 2:

[0065] A preparation method of an oxygen-containing high-temperature resistant C / SiC sealing strip modified by the sol-gel method, which is carried out according to the following steps:

[0066] I. Low-temperature plasma treatment:

[0067] Using argon as the working gas, under the conditions of an argon flow rate of 50 sccm and a radio frequency power of 100 W, the carbon fiber sealing strip is subjected to low-temperature plasma treatment for 10 min to obtain a plasma-treated carbon fiber sealing strip;

[0068] II. CVD deposition process:

[0069] The plasma-treated carbon fiber sealing strip is placed in the reaction chamber of the CVD reaction equipment, evacuated to 10 - 2 Pa, and then the mixed reaction gas is introduced. At the same time, the heating system is turned on, and the reaction chamber is heated to 1050 °C at a heating rate of 10 °C / min. Then, under the conditions of a sample rotation speed of 40 r / min, a reaction chamber pressure of 20 Pa, and a temperature of 1050 °C, the deposition reaction is carried out for 5 h. After the deposition is completed, the introduction of the mixed reaction gas is stopped, and the vacuum state is maintained to allow the reaction chamber to cool naturally to room temperature. Finally, it is taken out to obtain a CVD-deposited carbon fiber sealing strip;

[0070] The described mixed reaction gas is formed by mixing a silicon source gas, a carbon source gas, and a dilution gas;

[0071] The silicon source gas is SiH4; the carbon source gas is CH4; the dilution gas is hydrogen;

[0072] The purities of the silicon source gas, the carbon source gas, and the dilution gas are all ≥4N;

[0073] The volume ratio of the silicon source gas to the carbon source gas is 1:2; the volume ratio of the silicon source gas to the dilution gas is 1:15;

[0074] III. Preparation of a silica antioxidant layer by the sol-gel method:

[0075] Under the condition that the stirring speed is 300 r / min, tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid solution are stirred and mixed for 2 h to obtain a transparent sol. Then, the carbon fiber sealing strip after CVD deposition is immersed in the transparent sol, and the dipping and pulling method is used to pull the sealing strip at a uniform pulling speed of 2 mm / s, so that the sol is evenly attached to the surface of the sealing strip. Then, under the condition that the temperature is 60 °C, a gelling reaction is carried out for 2 h to form a silica gel layer. Finally, under an argon protection atmosphere, the temperature is raised to 500 °C at a heating rate of 5 °C / min, and under the conditions of an argon atmosphere and a temperature of 500 °C, heat preservation is carried out for 2 h to obtain a C / SiC sealing strip coated with a silica antioxidant layer;

[0076] The molar ratio of tetraethyl orthosilicate to absolute ethanol is 1:4; the molar ratio of tetraethyl orthosilicate to deionized water is 1:2; the molar ratio of tetraethyl orthosilicate to hydrochloric acid in the hydrochloric acid solution is 1:0.01; the concentration of the hydrochloric acid solution is 8%; the purities of tetraethyl orthosilicate and absolute ethanol are both ≥4N;

[0077] IV. Post-treatment:

[0078] The C / SiC sealing strip coated with a silica antioxidant layer is successively subjected to grinding and polishing treatments, and then under the conditions of an argon atmosphere and a temperature of 400 °C, low-temperature annealing treatment is carried out for 1 h to obtain a modified oxygen-containing high-temperature-resistant C / SiC sealing strip.

[0079] The carbon fiber sealing strip described in step I is a pretreated carbon fiber sealing strip, and the pretreatment is specifically carried out according to the following steps: Under the condition that the ultrasonic power is 300 W, it is successively placed in acetone and absolute ethanol and ultrasonically cleaned for 20 min each, and then under the condition that the temperature is 60 °C, it is dried for 3 h.

[0080] The carbon fiber sealing strip described in step I is woven from T300 carbon fiber bundles.

[0081] Comparative Example 1: The difference between this comparative example and Example 1 is that step three is cancelled. Others are the same as in Example 1.

[0082] Take 10 modified aerobic high-temperature resistant C / SiC sealing strips, accurately measure their initial mass m0, record the data, put the specimens into a muffle furnace, keep them in an oxygen atmosphere at a temperature of 800 °C for 24 hours to simulate the oxidation environment. After the oxidation treatment, take out the specimens and cool them to room temperature, then accurately weigh them again, record the mass as m1, and calculate the average oxidation weight gain rate according to the formula. Install the modified aerobic high-temperature resistant C / SiC sealing strips on a specific sealing test device, apply pressure (1000 Pa) to the sealing device to simulate the pressure environment in actual use, and conduct tests at a high temperature of 800 °C and in an air atmosphere. Use a gas leak detector to regularly detect the leakage situation at the seal, and take the time when leakage first occurs as the sealing performance retention time. The test results are as Figure 1 and Figure 2 shown.

[0083] Figure 1 It is a comparative chart of the oxidation weight gain rates of the aerobic high-temperature resistant C / SiC sealing strips prepared in Examples 1-2 and Comparative Example 1 at a high temperature of 800 °C; it can be seen from the figure that at a high temperature of 800 °C, the oxidation weight gain rates of the C / SiC sealing strips coated with a silica anti-oxidation layer are 4.8 and 6.1%, both lower than 10.2% of Comparative Example 1, indicating that coating a silica anti-oxidation layer is beneficial to reducing the oxidation of the sealing strips.

[0084] Figure 2 It is a comparative chart of the sealing performance retention times of the aerobic high-temperature resistant C / SiC sealing strips prepared in Examples 1-2 and Comparative Example 1 at a high temperature of 800 °C; as shown in the figure, it can be found that the sealing performances of Example 1 and Example 2 can be maintained for 28 h and 25 h at 800 °C, significantly higher than 12 h of Comparative Example 1 without a silica anti-oxidation layer, fully indicating that coating a silica anti-oxidation layer on the surface of the C / SiC sealing strip in the examples can effectively improve the high-temperature sealing performance of the sealing strip.

Claims

1. A preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by a sol-gel method, characterized in that It is carried out according to the following steps: I. Low-temperature plasma treatment: Using argon as the working gas, under the conditions that the argon flow rate is 50 sccm to 450 sccm and the radio frequency power is 20 W to 150 W, the carbon fiber sealing strip is subjected to low-temperature plasma treatment for 5 min to 100 min to obtain the carbon fiber sealing strip after plasma treatment; II. CVD deposition process: The carbon fiber sealing strip after plasma treatment is placed in the reaction chamber of the CVD reaction equipment and evacuated, then a mixed reaction gas is introduced, and at the same time, the heating system is turned on. The reaction chamber is heated to 1050 °C to 1550 °C at a heating rate of 10 °C / min to 15 °C / min. Then, under the conditions that the sample rotation speed is 15 r / min to 100 r / min, the reaction chamber pressure is 1 Pa to 40 Pa, and the temperature is 1050 °C to 1550 °C, the deposition reaction is carried out for 1 h to 10 h. After the deposition is completed, the introduction of the mixed reaction gas is stopped, and the vacuum state is maintained to allow the reaction chamber to cool naturally to room temperature. Finally, it is taken out to obtain the carbon fiber sealing strip after CVD deposition; The mixed reaction gas described above is composed of a silicon source gas, a carbon source gas, and a dilution gas; III. Preparation of silica antioxidant layer by sol-gel method: Tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrochloric acid solution are stirred and mixed evenly to obtain a transparent sol. Then, the carbon fiber sealing strip after CVD deposition is immersed in the transparent sol, and the dipping and pulling method is used to pull the sealing strip at a uniform pulling speed of 2 mm / s to 5 mm / s, so that the sol adheres evenly to the surface of the sealing strip. Then, a gelation reaction is carried out to form a silica gel layer. Finally, under the conditions of an argon atmosphere and a temperature of 500 °C to 1000 °C, it is kept warm for 1 h to 2 h to obtain a C / SiC sealing strip coated with a silica antioxidant layer; IV. Post-treatment: The C / SiC sealing strip coated with a silica antioxidant layer is successively subjected to grinding and polishing treatments, and then low-temperature annealing treatment, thus completing the preparation method of the aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method.

2. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that The carbon fiber sealing strip described in step I is a pre-treated carbon fiber sealing strip, and the pretreatment is specifically carried out according to the following steps: Under the condition that the ultrasonic power is 300 W to 500 W, it is successively placed in acetone and absolute ethanol and ultrasonically cleaned for 15 min to 120 min, and then dried for 1 h to 10 h under the condition that the temperature is 60 °C to 180 °C.

3. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that The carbon fiber sealing strip described in step I is woven from T300 carbon fiber bundles.

4. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that The silicon source gas described in step II is SiH4; the carbon source gas described in step II is CH4; the dilution gas described in step II is hydrogen.

5. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that The purities of the silicon source gas, carbon source gas, and dilution gas described in step II are all ≥4N.

6. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that The volume ratio of the silicon source gas to the carbon source gas described in step II is 1:(1 - 5); the volume ratio of the silicon source gas to the dilution gas described in step II is 1:(1 - 20).

7. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method according to claim 1, characterized in that In step two, evacuate the air to 10 -4 Pa to 10 -2 Pa.

8. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that In step 3, the molar ratio of tetraethyl orthosilicate to absolute ethanol is 1:(4 - 6); the molar ratio of tetraethyl orthosilicate to deionized water is 1:(2 - 4); the molar ratio of tetraethyl orthosilicate to hydrochloric acid in the hydrochloric acid solution is 1:(0.01 - 0.03); the mass percentage of the hydrochloric acid solution is 2% - 20%; the purities of tetraethyl orthosilicate and absolute ethanol in step 3 are both ≥4N.

9. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by sol-gel method according to claim 1, characterized in that In step 3, under the condition that the stirring speed is 300 r / min - 500 r / min, tetraethyl orthosilicate, absolute ethanol, deionized water and hydrochloric acid solution are stirred and mixed for 1 h - 2 h; the gelation reaction in step 3 is specifically carried out under the condition that the temperature is 60°C - 100°C for 1 h - 2 h; in step 3, under the argon protection atmosphere, the temperature is raised to 500°C - 1000°C at a heating rate of 5°C / min - 10°C / min.

10. The preparation method of an aerobic high-temperature resistant C / SiC sealing strip modified by the sol-gel method according to claim 1, characterized in that The low-temperature annealing treatment in step 4 is specifically carried out under the argon atmosphere and at a temperature of 300°C - 800°C for 1 h - 10 h.

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