A method for enhancing the oxidation resistance of carbon-carbon composite materials using titanium boride

Abstract

The invention provides a method for enhancing the oxidation resistance of a carbon-carbon composite material by utilizing titanium boride, and belongs to the technical field of carbon-carbon composite materials. The method comprises the steps of preparing a boron-titanium mixture, preparing functional carbon fibers, preparing a mixture, and post-processing. The step of preparing the mixture comprises the steps of putting the boron-titanium mixture, isocyanate-modified carbon fibers, Schiff base-modified carbon fibers, and deionized water into a ball mill for ball milling, adding pentaerythritol stearate and sodium dodecylaminopropionate after the ball milling, maintaining the temperature and the rotation speed, and continuing the ball milling for 15-20 minutes. After the ball milling, drying is performed to obtain a primary mixture, and then heating the mixture to 1400-1550° C. at a rate of 4.5-5.5° C. / min under an argon atmosphere, keeping the temperature for 1.8-2.5 hours, and naturally recovering to room temperature after the insulation is completed to obtain a mixture. The carbon-carbon composite material obtained by the method of the invention has high strength and good oxidation resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon-carbon composite materials, and in particular relates to a method for enhancing the oxidation resistance of a carbon-carbon composite material by utilizing titanium boride. Background Art

[0002] Carbon-carbon composite materials have the advantages of low density, high strength, high specific modulus, high thermal conductivity, low expansion coefficient, good friction performance, high dimensional stability and good high-temperature stability. They are one of the few alternative materials for applications above 1650°C and are considered to be one of the most promising high-temperature materials. They are widely used in aerospace, energy, chemical industry, machinery and other fields.

[0003] However, carbon-carbon composites undergo oxidation reactions in an aerobic environment above 400°C, causing their performance to drop sharply, limiting their application in a wider range of fields.

[0004] Therefore, improving the oxidation resistance of carbon-carbon composites has become the focus of current research.

[0005] In this regard, CN117735993A discloses a preparation process for a high-temperature stable carbon-carbon composite material, specifically disclosing the use of aluminum oxide as a modifier to modify silicon carbide; using an acid solution to perform surface activation treatment on carbon fiber, mixing the activated carbon fiber with the modified silicon carbide, and then adding nano-carbon black or nano-silicon powder to obtain a mixture A; after the mixture A is formed, pre-cured, and carbonized at high temperature, a silane coupling agent and a high-temperature wear-resistant ceramic material are used as surface treatment materials for surface treatment, and after curing, a high-temperature stable carbon-carbon composite material is obtained.

[0006] The carbon-carbon composite material produced by this patent has good wear resistance and thermal stability up to 1450°C. However, under a high temperature environment of 1450°C, the rate of decrease in strength performance is still high, which shortens the service life of the carbon-carbon composite material.

[0007] Titanium boride has a melting point of 2980°C, high hardness, good chemical stability and oxidation resistance, and is mainly used to prepare ceramic products. Introducing titanium boride into carbon-carbon composite materials is expected to improve their oxidation resistance and extend the service life of the composite materials.

[0008] However, titanium boride has poor compatibility with the resin matrix and cannot form a good bonding interface between them, resulting in its inability to be evenly dispersed in the carbon-carbon composite material, which ultimately affects the overall performance of the carbon-carbon composite material. In addition, current research on the antioxidant properties of titanium boride-enhanced carbon-carbon composites is still insufficient, and there is a lack of effective methods to achieve uniform compounding of titanium boride and carbon-carbon composites, and to ensure the stable improvement of the performance of carbon-carbon composites. Summary of the invention

[0009] In order to solve the technical problems existing in the prior art, the present invention provides a method for enhancing the oxidation resistance of a carbon-carbon composite material by using titanium boride. The prepared carbon-carbon composite material has good oxidation resistance, excellent strength performance and good stability.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A method for enhancing the oxidation resistance of a carbon-carbon composite material by using titanium boride, comprising the steps of preparing a boron-titanium mixture, preparing a functional carbon fiber, preparing a mixed material, and post-processing, as follows:

[0012] 1. Preparation of Boron-Titanium Mixture

[0013] Phenolic resin, ethyl borate and tetrabutyl titanate are mixed, placed in a ball mill, ethanol solution is added, and ball milling is performed. The ball milling time is 47-53 minutes, the ball milling speed is 220-240 rpm, the ball milling temperature is 63-67° C., and the ball-to-material ratio is 3-5:1. After the ball milling is completed, the mixture is filtered, washed and dried to obtain a boron-titanium mixture.

[0014] The mass concentration of the ethanol solution is 15-20%;

[0015] The mass ratio of the phenolic resin, ethyl borate, tetrabutyl titanate and ethanol solution is 16-20:1.1-1.3:1.0-1.4:68-72.

[0016] 2. Preparation of functional carbon fibers

[0017] (1) Infiltration

[0018] Put the carbon fiber into the hydrogen peroxide solution, raise the temperature to 45-50°C, stir for 55-64 minutes, stir evenly, add polyglycerol fatty acid ester and dodecyl dihydroxyethyl betaine, continue stirring for 13-18 minutes, filter, wash and dry after stirring to obtain the impregnated carbon fiber;

[0019] The carbon fiber has a diameter of 180-220 nm and a length of 0.4-0.6 mm;

[0020] The mass concentration of the hydrogen peroxide solution is 22-24%;

[0021] The mass ratio of the carbon fiber, the hydrogen peroxide solution, the polyglycerol fatty acid ester and the dodecyl dihydroxyethyl betaine is 10-14:82-88:0.5-0.8:0.7-1.0;

[0022] (2) Isocyanate modification

[0023] Add diphenylmethane diisocyanate to acetone and stir until completely dissolved, then add the soaked carbon fiber, raise the temperature to 48-53°C, stir for 3.4-3.7h, and stir at a speed of 132-146rpm. After stirring, place in a water bath at 68-72°C to evaporate the acetone, and dry at 81-85°C for 20-24h to obtain isocyanate-modified carbon fiber;

[0024] The mass volume ratio of the acetone, diphenylmethane diisocyanate, and impregnated carbon fiber is 390-406 mL: 2.72-2.76 g: 1.85-1.90 g;

[0025] (3) Schiff base modification

[0026] Add anhydrous ethanol to sodium alginate, stir evenly at 35-38°C, then add sodium periodate, and perform ultrasonic treatment under light-proof conditions. The ultrasonic treatment time is 27-35 minutes, the ultrasonic power is 252-265W, and the ultrasonic frequency is 56-60kHz. After the ultrasonic treatment is completed, the reaction is carried out in the dark for 4.4-4.6 hours, and the oxidized sodium alginate is obtained after filtering and drying.

[0027] The mass volume ratio of the sodium alginate, anhydrous ethanol and sodium periodate is 9.3-9.7 g:480-520 mL:5.5-6.0 g;

[0028] The impregnated carbon fiber is placed in a 30-34wt% ethanol solution, 3-aminopropyltriethoxysilane and tetraethylenepentamine are added, the temperature is raised to 66-70°C for stirring reaction, and the reaction time is 5.8-6.2h. After the reaction is completed, amino carbon fiber is obtained;

[0029] The mass ratio of the impregnated carbon fiber, ethanol solution, 3-aminopropyltriethoxysilane, and tetraethylenepentamine is 10.3-10.7:96-103:0.72-0.77:0.33-0.36;

[0030] Add amino carbon fiber and oxidized sodium alginate to a phosphate buffer solution with a pH value of 7.4, stir evenly and react for 8.3-8.8 hours. After the reaction is completed, filter and wash, freeze-dry at -45 to -40°C for 18-22 hours, and wait for the mixture to naturally return to room temperature to obtain Schiff base modified carbon fiber.

[0031] The mass volume ratio of the phosphate buffer, amino carbon fiber and oxidized sodium alginate is 495-510 mL: 8.2-8.7 g: 7.0-7.5 g.

[0032] 3. Preparation of Mixture

[0033] Put the boron-titanium mixture, isocyanate-modified carbon fiber, Schiff base-modified carbon fiber and deionized water into a ball mill for ball milling, the ball milling temperature is 70-74°C, the ball milling speed is 195-210rpm, the ball milling time is 32-37min, after the ball milling, add pentaerythritol stearate and sodium dodecylaminopropionate, maintain the temperature and speed, continue ball milling for 15-20min, after the ball milling, dry to obtain a primary mixture, and then heat to 1400-1550°C at a rate of 4.5-5.5°C / min under an argon atmosphere, keep warm for 1.8-2.5h, and naturally return to room temperature after the insulation to obtain a mixture;

[0034] The mass ratio of the boron-titanium mixture, isocyanate-modified carbon fiber, Schiff base-modified carbon fiber, deionized water, pentaerythritol stearate, and sodium dodecylaminopropionate is 34.1-34.5:2.2-2.4:3.2-3.6:195-206:1.3-1.5:1.6-2.0.

[0035] 4. Post-processing

[0036] The mixture is pressed into shape at a pressure of 6.3-6.7MPa and a temperature of 162-167°C for 3.8-4.3h. After the pressing time, a molded product is obtained. The molded product is placed in an argon atmosphere, and the temperature is increased to 1250-1340°C at a rate of 12-14°C / min, and kept warm for 32-37min. After the insulation is completed, the temperature is increased to 1900-2050°C at a rate of 9.5-10.5°C / min, and kept warm for 16-25min. After the insulation is completed, the temperature is increased to 2410-2450°C at a rate of 5.8-6.2°C / min, and kept warm for 1.3-2.0h. After the insulation is completed, the temperature is naturally reduced to room temperature to obtain a carbon-carbon composite material.

[0037] Compared with the prior art, the present invention has achieved the following beneficial effects:

[0038] 1. The present invention uses a hydrogen peroxide solution and a surfactant to impregnate the carbon fiber, so that the surface of the carbon fiber contains more hydroxyl groups and reduces the aggregation between them. Then different functional treatments are performed. First, the carbon fiber is modified with isocyanate to improve the compatibility of the carbon fiber with the carbon source phenolic resin, and then amino carbon fiber is prepared. The amino carbon fiber is reacted with oxidized sodium alginate and cross-linked with Schiff base bonds so that the carbon fiber presents a stable cross-linked network structure. The two functional carbon fibers are composited, which can present a good combination with the carbon source, and the connection is stable, which effectively enhances the strength and stability of the composite material. The present invention also uses ethyl borate as a boron source and tetrabutyl titanate as a titanium source, and combines with phenolic resin to prepare a boron-titanium mixture. After high-temperature treatment, the boron source and the titanium source react to generate titanium boride, so that the titanium boride is well dispersed in the phenolic resin matrix, and the strength performance is enhanced. The initial oxidation temperature of the composite material is also increased, so that it can maintain stability for a longer time in a high-temperature aerobic environment;

[0039] 2. The carbon-carbon composite material prepared by the method of the present invention has a compressive strength of 187.0-188.9 MPa, a flexural strength of 168.4-171.3 MPa, and a tensile strength of 127.5-129.6 MPa;

[0040] 3. The carbon-carbon composite material prepared by the method of the present invention was heated to 700°C at a rate of 6.0°C / min, kept warm for 4.0 hours, and then heated to 1250°C at a rate of 3.0°C / min, kept warm for 4.0 hours. After the end of the heat preservation, the mass loss rate was measured to be 0.21-0.25%;

[0041] 4. The carbon-carbon composite material prepared by the method of the present invention is heated to 500°C at a rate of 10.0°C / min in an air atmosphere, kept warm for 12.0 hours, then heated to 1000°C at a rate of 5.0°C / min, kept warm for 12.0 hours, and then heated to 1450°C at a rate of 2.0°C / min, kept warm for 24.0 hours. After the insulation is completed, it is naturally cooled to room temperature; the above operation is regarded as one cycle. After 3 cycles of treatment, the compressive strength is measured again as 180.1-184.0MPa, the flexural strength is 158.5-163.1MPa, and the tensile strength is 120.9-124.5MPa. DETAILED DESCRIPTION

[0042] In order to more clearly understand the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described.

[0043] Example 1

[0044] 1. Preparation of Boron-Titanium Mixture

[0045] 18g of phenolic resin, 1.2g of ethyl borate and 1.2g of tetrabutyl titanate were mixed, placed in a ball mill, 70g of ethanol solution was added, and ball milling was performed. The ball milling time was 50min, the ball milling speed was 230rpm, the ball milling temperature was 65°C, and the ball-to-material ratio was 4:1. After the ball milling was completed, the mixture was filtered, washed and dried to obtain a boron-titanium mixture.

[0046] The mass concentration of the ethanol solution is 17%.

[0047] 2. Preparation of functional carbon fibers

[0048] (1) Infiltration

[0049] 12g of carbon fiber was put into 85g of hydrogen peroxide solution, the temperature was raised to 47°C, and stirred for 60min. After stirring evenly, 0.6g of polyglycerol fatty acid ester and 0.9g of dodecyl dihydroxyethyl betaine were added, and stirring was continued for 15min. After the stirring was completed, the mixture was filtered, washed and dried to obtain the impregnated carbon fiber;

[0050] The diameter of the carbon fiber is 200nm and the length is 0.5mm;

[0051] The mass concentration of the hydrogen peroxide solution is 23%;

[0052] (2) Isocyanate modification

[0053] 2.74 g of diphenylmethane diisocyanate was added to 400 mL of acetone and stirred until completely dissolved, and then 1.88 g of impregnated carbon fiber was added, the temperature was raised to 50 ° C, and stirred for 3.5 h at a stirring speed of 140 rpm. After the stirring was completed, the acetone was evaporated in a water bath at 70 ° C, and dried at 83 ° C for 22 h to obtain isocyanate-modified carbon fiber;

[0054] (3) Schiff base modification

[0055] Add 500 mL of anhydrous ethanol to 9.5 g of sodium alginate, stir evenly at 37° C., then add 5.7 g of sodium periodate, and perform ultrasonic treatment under light-proof conditions. The ultrasonic time is 30 min, the ultrasonic power is 260 W, and the ultrasonic frequency is 58 kHz. After the ultrasonic treatment, react in the dark for 4.5 h, filter and dry to obtain oxidized sodium alginate.

[0056] 10.5 g of the impregnated carbon fiber was placed in 100 g of a 32 wt% ethanol solution, 0.75 g of 3-aminopropyltriethoxysilane and 0.35 g of tetraethylenepentamine were added, the temperature was raised to 68°C for stirring reaction, and the reaction time was 6.0 h. After the reaction was completed, amino carbon fiber was obtained;

[0057] 8.4 g of amino carbon fiber and 7.3 g of oxidized sodium alginate were added to 500 mL of phosphate buffer solution with a pH of 7.4, and the mixture was stirred evenly for a reaction for 8.5 h. After the reaction, the mixture was filtered and washed, and then freeze-dried at -42 °C for 20 h. The carbon fiber was then naturally restored to room temperature to obtain Schiff base modified carbon fiber.

[0058] 3. Preparation of Mixture

[0059] 34.3g of boron-titanium mixture, 2.3g of isocyanate-modified carbon fiber, 3.4g of Schiff base-modified carbon fiber and 200g of deionized water were put into a ball mill for ball milling. The ball milling temperature was 72°C, the ball milling speed was 203rpm, and the ball milling time was 35min. After the ball milling, 1.4g of pentaerythritol stearate and 1.8g of sodium dodecylaminopropionate were added. The temperature and speed were maintained and the ball milling was continued for 17min. After the ball milling was completed, it was dried to obtain a primary mixture. Then, it was heated to 1500°C at a rate of 5°C / min under an argon atmosphere and kept warm for 2.0h. After the insulation was completed, it was naturally restored to room temperature to obtain a mixture.

[0060] 4. Post-processing

[0061] The mixture was pressed under the conditions of a pressure of 6.5MPa and a temperature of 165°C for 4.0h. After the pressing time, a molded product was obtained. The molded product was placed in an argon atmosphere, heated to 1300°C at a rate of 13°C / min, and kept warm for 35min. After the insulation, the temperature was increased to 2000°C at a rate of 10°C / min, and kept warm for 20min. After the insulation, the temperature was increased to 2430°C at a rate of 6.0°C / min, and kept warm for 1.5h. After the insulation, the temperature was naturally lowered to room temperature to obtain a carbon-carbon composite material.

[0062] Example 2

[0063] 1. Preparation of Boron-Titanium Mixture

[0064] 16g of phenolic resin, 1.1g of ethyl borate and 1.0g of tetrabutyl titanate were mixed, placed in a ball mill, 68g of ethanol solution was added, and ball milling was performed. The ball milling time was 47min, the ball milling speed was 220rpm, the ball milling temperature was 63°C, and the ball-to-material ratio was 3:1. After the ball milling was completed, the mixture was filtered, washed and dried to obtain a boron-titanium mixture.

[0065] The mass concentration of the ethanol solution is 15%.

[0066] 2. Preparation of functional carbon fibers

[0067] (1) Infiltration

[0068] 10g of carbon fiber was put into 82g of hydrogen peroxide solution, the temperature was raised to 45°C, and the mixture was stirred for 55min. After stirring evenly, 0.5g of polyglycerol fatty acid ester and 0.7g of dodecyl dihydroxyethyl betaine were added, and the mixture was stirred for 13min. After the stirring was completed, the mixture was filtered, washed, and dried to obtain the impregnated carbon fiber.

[0069] The diameter of the carbon fiber is 180nm and the length is 0.4mm;

[0070] The mass concentration of the hydrogen peroxide solution is 22%;

[0071] (2) Isocyanate modification

[0072] Add 2.72 g of diphenylmethane diisocyanate to 390 mL of acetone and stir until completely dissolved, then add 1.85 g of soaked carbon fiber, raise the temperature to 48 ° C, stir for 3.4 h, and the stirring speed is 132 rpm. After the stirring is completed, place it in a water bath at 68 ° C to evaporate the acetone, and dry it at 81 ° C for 24 h to obtain isocyanate-modified carbon fiber;

[0073] (3) Schiff base modification

[0074] Add 480 mL of anhydrous ethanol to 9.3 g of sodium alginate, stir evenly at 35° C., then add 5.5 g of sodium periodate, and perform ultrasonic treatment under light-proof conditions. The ultrasonic time is 27 min, the ultrasonic power is 252 W, and the ultrasonic frequency is 56 kHz. After the ultrasonic treatment, react in the dark for 4.4 h, filter and dry to obtain oxidized sodium alginate.

[0075] 10.3 g of the impregnated carbon fiber was placed in 96 g of a 30 wt% ethanol solution, 0.72 g of 3-aminopropyltriethoxysilane and 0.33 g of tetraethylenepentamine were added, the temperature was raised to 66 ° C for stirring reaction, and the reaction time was 5.8 h. After the reaction was completed, amino carbon fiber was obtained;

[0076] 8.2 g of amino carbon fiber and 7.0 g of oxidized sodium alginate were added to 495 mL of phosphate buffer solution with a pH of 7.4, and the mixture was stirred evenly for a reaction for 8.3 h. After the reaction, the mixture was filtered and washed, and then freeze-dried at -40 °C for 22 h. The carbon fiber was then naturally restored to room temperature to obtain Schiff base modified carbon fiber.

[0077] 3. Preparation of Mixture

[0078] 34.1g of boron-titanium mixture, 2.2g of isocyanate-modified carbon fiber, 3.2g of Schiff base-modified carbon fiber and 195g of deionized water were put into a ball mill for ball milling. The ball milling temperature was 70°C, the ball milling speed was 195rpm, and the ball milling time was 32min. After the ball milling, 1.3g of pentaerythritol stearate and 1.6g of sodium dodecylaminopropionate were added. The temperature and speed were maintained and the ball milling was continued for 15min. After the ball milling was completed, it was dried to obtain a primary mixture. Then, it was heated to 1400°C at a rate of 4.5°C / min under an argon atmosphere and kept warm for 2.5h. After the insulation was completed, it was naturally restored to room temperature to obtain a mixture.

[0079] 4. Post-processing

[0080] The mixture was pressed under the conditions of a pressure of 6.3MPa and a temperature of 162°C for 3.8h. After the pressing time, a molded product was obtained. The molded product was placed in an argon atmosphere, and the temperature was increased to 1250°C at a rate of 12°C / min and kept warm for 32min. After the insulation was completed, the temperature was increased to 1900°C at a rate of 9.5°C / min and kept warm for 16min. After the insulation was completed, the temperature was increased to 2410°C at a rate of 5.8°C / min and kept warm for 2.0h. After the insulation was completed, the temperature was naturally lowered to room temperature to obtain a carbon-carbon composite material.

[0081] Example 3

[0082] 1. Preparation of Boron-Titanium Mixture

[0083] 20g of phenolic resin, 1.3g of ethyl borate and 1.4g of tetrabutyl titanate were mixed, placed in a ball mill, 72g of ethanol solution was added, and ball milling was performed. The ball milling time was 53min, the ball milling speed was 240rpm, the ball milling temperature was 67°C, and the ball-to-material ratio was 5:1. After the ball milling was completed, the mixture was filtered, washed and dried to obtain a boron-titanium mixture.

[0084] The mass concentration of the ethanol solution is 20%.

[0085] 2. Preparation of functional carbon fibers

[0086] (1) Infiltration

[0087] 14g of carbon fiber was added to 88g of hydrogen peroxide solution, the temperature was raised to 50°C, and the mixture was stirred for 64 minutes. After stirring evenly, 0.8g of polyglycerol fatty acid ester and 1.0g of dodecyl dihydroxyethyl betaine were added, and the mixture was stirred for 18 minutes. After the stirring was completed, the mixture was filtered, washed, and dried to obtain the impregnated carbon fiber.

[0088] The diameter of the carbon fiber is 220nm and the length is 0.6mm;

[0089] The mass concentration of the hydrogen peroxide solution is 24%;

[0090] (2) Isocyanate modification

[0091] Add 2.76 g of diphenylmethane diisocyanate to 406 mL of acetone and stir until completely dissolved, then add 1.90 g of soaked carbon fiber, raise the temperature to 53 ° C, stir for 3.7 h, and the stirring speed is 146 rpm. After the stirring is completed, place it in a water bath at 72 ° C to evaporate the acetone, and dry it at 85 ° C for 20 h to obtain isocyanate-modified carbon fiber;

[0092] (3) Schiff base modification

[0093] Add 520 mL of anhydrous ethanol to 9.7 g of sodium alginate, stir evenly at 38° C., then add 6.0 g of sodium periodate, and perform ultrasonic treatment under light-proof conditions. The ultrasonic time is 35 min, the ultrasonic power is 265 W, and the ultrasonic frequency is 60 kHz. After the ultrasonic treatment, react in the dark for 4.6 h, filter and dry to obtain oxidized sodium alginate.

[0094] 10.7 g of the impregnated carbon fiber was placed in 103 g of a 34 wt% ethanol solution, 0.77 g of 3-aminopropyltriethoxysilane and 0.36 g of tetraethylenepentamine were added, the temperature was raised to 70°C for stirring reaction, and the reaction time was 6.2 h. After the reaction was completed, amino carbon fiber was obtained;

[0095] 8.7 g of amino carbon fiber and 7.5 g of oxidized sodium alginate were added to 510 mL of phosphate buffer solution with a pH of 7.4, and the mixture was stirred evenly for reaction for 8.8 h. After the reaction, the mixture was filtered and washed, and then freeze-dried at -45 °C for 18 h, and then naturally recovered to room temperature to obtain Schiff base modified carbon fiber.

[0096] 3. Preparation of Mixture

[0097] 34.5g of boron-titanium mixture, 2.4g of isocyanate-modified carbon fiber, 3.6g of Schiff base-modified carbon fiber and 206g of deionized water were put into a ball mill for ball milling. The ball milling temperature was 74°C, the ball milling speed was 210rpm, and the ball milling time was 37min. After the ball milling, 1.5g of pentaerythritol stearate and 2.0g of sodium dodecylaminopropionate were added. The temperature and speed were maintained and the ball milling was continued for 20min. After the ball milling, it was dried to obtain a primary mixture. Then, it was heated to 1550°C at a rate of 5.5°C / min under an argon atmosphere and kept warm for 1.8h. After the insulation was completed, it was naturally restored to room temperature to obtain a mixture.

[0098] 4. Post-processing

[0099] The mixture was pressed into shape at a pressure of 6.7 MPa and a temperature of 167°C for 4.3 hours. After the pressing time, a molded product was obtained. The molded product was placed in an argon atmosphere, and the temperature was increased to 1340°C at a rate of 14°C / min and kept warm for 37 minutes. After the insulation was completed, the temperature was increased to 2050°C at a rate of 10.5°C / min and kept warm for 25 minutes. After the insulation was completed, the temperature was increased to 2450°C at a rate of 6.2°C / min and kept warm for 1.3 hours. After the insulation was completed, the temperature was naturally lowered to room temperature to obtain a carbon-carbon composite material.

[0100] Comparative Example 1

[0101] Based on Example 1, the changes are as follows:

[0102] (1) Omit the preparation of the boron-titanium mixture; in the step of preparing the mixture, replace the boron-titanium mixture with an equal amount of phenolic resin;

[0103] (2) In the step of preparing the functional carbon fiber, the isocyanate modification step is omitted; in the step of preparing the mixture, the isocyanate-modified carbon fiber is replaced with an equal amount of impregnated carbon fiber;

[0104] The rest of the operations are the same.

[0105] Comparative Example 2

[0106] Based on Example 1, the changes are as follows:

[0107] (1) In the step of preparing functional carbon fiber, the Schiff base modification step is omitted; in the step of preparing the mixture, the Schiff base modified carbon fiber is replaced with an equal amount of impregnated carbon fiber;

[0108] (2) Replace equal amounts of pentaerythritol stearate and sodium laurylaminopropionate with deionized water;

[0109] The rest of the operations are the same.

[0110] Performance Testing

[0111] 1. Strength performance

[0112] The carbon-carbon composite materials prepared in Examples 1-3 and Comparative Examples 1-2 were tested for strength properties, and the results were as follows:

[0113]

[0114] 2. Antioxidant

[0115] (1) Quality loss

[0116] The carbon-carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-2 were heated to 700°C at a rate of 6.0°C / min, kept warm for 4.0 hours, and then heated to 1250°C at a rate of 3.0°C / min, kept warm for 4.0 hours. After the end of the heat preservation, the mass loss was tested, and the results were as follows:

[0117]

[0118] (2) Strength retention performance

[0119] The carbon-carbon composite materials obtained in Examples 1-3 and Comparative Examples 1-2 were heated to 500°C at a rate of 10.0°C / min in an air atmosphere, kept warm for 12.0h, then heated to 1000°C at a rate of 5.0°C / min, kept warm for 12.0h, and then heated to 1450°C at a rate of 2.0°C / min, kept warm for 24.0h. After the end of the heat preservation, the temperature was naturally lowered to room temperature; the above operation was regarded as a cycle. After 3 cycles, the strength performance was tested again. The test results are as follows:

[0120]

[0121] The present invention uses a hydrogen peroxide solution and a surfactant to perform an impregnation treatment on the carbon fiber, so that the surface of the carbon fiber contains more hydroxyl groups and the aggregation between the carbon fiber is reduced. Then different functional treatments are performed. First, the carbon fiber is modified with isocyanate to improve the compatibility of the carbon fiber with the carbon source phenolic resin. Then, amino carbon fiber is prepared. The amino carbon fiber is reacted with oxidized sodium alginate and cross-linked with Schiff base bonds to make the carbon fiber present a stable cross-linked network structure. The two functional carbon fibers are composited, which can present a good combination with the carbon source and a stable connection, and the strength and stability of the composite material are effectively enhanced. The present invention also uses ethyl borate as a boron source and tetrabutyl titanate as a titanium source, and combines with phenolic resin to prepare a boron-titanium mixture. After high-temperature treatment, the boron source and the titanium source react to generate titanium boride, so that the titanium boride is well dispersed in the phenolic resin matrix, the strength performance is enhanced, and the initial oxidation temperature of the composite material is also increased, so that the composite material can maintain stability for a longer time in a high-temperature oxygen environment.

[0122] In Comparative Example 1, the preparation of the boron-titanium mixture is omitted. In the step of preparing the mixture, the boron-titanium mixture is replaced by phenolic resin in equal amounts. The omission of the boron source and the titanium source reduces the initial oxidation temperature of the composite material, while reducing the strength performance to a certain extent. In Comparative Example 1, the isocyanate-modified carbon fiber is replaced by the impregnated carbon fiber in equal amounts, which reduces the compatibility and interface bonding ability with the phenolic resin, thereby reducing the strength performance and antioxidant performance of the composite material and shortening the service life.

[0123] Comparative Example 2 omits the Schiff base modified carbon fiber and replaces it with impregnated carbon fiber, which on the one hand affects the strength enhancement of the carbon fiber for the composite material. In addition, the omission of the Schiff base modified carbon fiber makes the connection between the carbon fiber and the phenolic resin weaker, and its strength performance in a high-temperature aerobic environment is greatly reduced. In addition, in the preparation step of the mixture in Comparative Example 2, pentaerythritol stearate and sodium dodecylaminopropionate components are omitted, which reduces the uniform dispersion performance in the mixing step, thereby weakening the homogeneity of the mixture. After pressing and carbonization, the obtained composite material has poor strength and poor antioxidant properties, which seriously limits the scope of application.

[0124] Unless otherwise specified, all ratios and percentages described in the present invention are by mass ratios and percentages are by mass percentages.

[0125] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for enhancing the oxidation resistance of a carbon-carbon composite material using titanium boride, characterized in that: It includes the steps of preparing a boron-titanium mixture, preparing functional carbon fibers, preparing a mixed material, and post-processing; The step of preparing the boron-titanium mixture is to mix phenolic resin, ethyl borate and tetrabutyl titanate, place the mixture in a ball mill, add an ethanol solution, and perform ball milling. After the ball milling is completed, the mixture is filtered, washed and dried to obtain the boron-titanium mixture. The preparation of functional carbon fibers includes impregnation, isocyanate modification and Schiff base modification; wherein the functional carbon fibers include isocyanate modified carbon fibers and Schiff base modified carbon fibers; The impregnation step comprises: putting the carbon fiber into a hydrogen peroxide solution, raising the temperature to 45-50° C., stirring for 55-64 minutes, adding polyglycerol fatty acid ester and dodecyl dihydroxyethyl betaine after stirring evenly, and continuing to stir for 13-18 minutes. After the stirring is completed, filtering, washing and drying are performed to obtain the impregnated carbon fiber; The isocyanate modification step comprises adding diphenylmethane diisocyanate to acetone and stirring until it is completely dissolved, then adding the impregnated carbon fiber and stirring to react, after the stirring is completed, removing the acetone and drying to obtain the isocyanate modified carbon fiber; The Schiff base modification step is to place the impregnated carbon fiber in a 30-34wt% ethanol solution, add 3-aminopropyltriethoxysilane and tetraethylenepentamine, raise the temperature to 66-70°C for stirring reaction, and the reaction time is 5.8-6.2h. After the reaction is completed, amino carbon fiber is obtained; amino carbon fiber and oxidized sodium alginate are added to a phosphate buffer solution with a pH of 7.4, and the mixture is stirred evenly and reacted for 8.3-8.8h. After the reaction is completed, the mixture is filtered and washed, and then placed at -45 to -40°C for freeze drying for 18-22h, and then naturally recovered to room temperature to obtain Schiff base modified carbon fiber; The step of preparing the mixture is to put the boron-titanium mixture, isocyanate-modified carbon fiber, Schiff base-modified carbon fiber and deionized water into a ball mill for ball milling, add pentaerythritol stearate and sodium dodecylaminopropionate after the ball milling, continue the ball milling, dry after the ball milling to obtain a primary mixture, and then heat and keep the temperature under an argon atmosphere, and naturally return to room temperature after the insulation to obtain a mixture; The post-processing step is to press the mixture into a molded product, place the molded product in an argon atmosphere, heat it up, and keep it warm. After the insulation is completed, the temperature is naturally lowered to room temperature to obtain a carbon-carbon composite material.

2. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 1, characterized in that: In the step of preparing the boron-titanium mixture, the ball milling time is 47-53 min, the ball milling speed is 220-240 rpm, the ball milling temperature is 63-67° C., and the ball-to-material ratio is 3-5:

1. The mass concentration of the ethanol solution is 15-20%; The mass ratio of the phenolic resin, ethyl borate, tetrabutyl titanate and ethanol solution is 16-20:1.1-1.3:1.0-1.4:68-72.

3. The method for enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 1, characterized in that: In the impregnation step, the carbon fiber has a diameter of 180-220 nm and a length of 0.4-0.6 mm; The mass concentration of the hydrogen peroxide solution is 22-24%; The mass ratio of the carbon fiber, the hydrogen peroxide solution, the polyglycerol fatty acid ester and the dodecyl dihydroxyethyl betaine is 10-14:82-88:0.5-0.8:0.7-1.

0.

4. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 1, characterized in that: In the isocyanate modification step, the stirring reaction has a reaction temperature of 48-53° C., a stirring time of 3.4-3.7 h, and a stirring speed of 132-146 rpm; The mass volume ratio of the acetone, diphenylmethane diisocyanate and impregnated carbon fiber is 390-406 mL: 2.72-2.76 g: 1.85-1.90 g.

5. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 1, characterized in that: In the Schiff base modification step, the preparation method of the oxidized sodium alginate is to add anhydrous ethanol to the sodium alginate, stir evenly at 35-38° C., then add sodium periodate, and perform ultrasonic treatment under light-proof conditions, wherein the ultrasonic time is 27-35 minutes, the ultrasonic power is 252-265W, and the ultrasonic frequency is 56-60kHz. After the ultrasonic treatment, the reaction is carried out in the dark for 4.4-4.6 hours, and the oxidized sodium alginate is obtained after filtering and drying. The mass volume ratio of the sodium alginate, anhydrous ethanol and sodium periodate is 9.3-9.7 g:480-520 mL:5.5-6.0 g.

6. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 5, characterized in that: In the Schiff base modification step, the mass ratio of the impregnated carbon fiber, the ethanol solution, the 3-aminopropyltriethoxysilane, and the tetraethylenepentamine is 10.3-10.7:96-103:0.72-0.77:0.33-0.36; The mass volume ratio of the phosphate buffer, amino carbon fiber and oxidized sodium alginate is 495-510 mL: 8.2-8.7 g: 7.0-7.5 g.

7. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 1, characterized in that: The step of preparing the mixture is to put the boron-titanium mixture, isocyanate-modified carbon fiber, Schiff base-modified carbon fiber and deionized water into a ball mill for ball milling, the ball milling temperature is 70-74°C, the ball milling speed is 195-210rpm, the ball milling time is 32-37min, after the ball milling, add pentaerythritol stearate and sodium dodecylaminopropionate, maintain the temperature and speed, continue ball milling for 15-20min, after the ball milling, dry to obtain a primary mixture, and then heat to 1400-1550°C at a rate of 4.5-5.5°C / min in an argon atmosphere, keep warm for 1.8-2.5h, and naturally return to room temperature after the insulation to obtain a mixture.

8. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 7, characterized in that: In the step of preparing the mixture, the mass ratio of the boron-titanium mixture, isocyanate-modified carbon fiber, Schiff base-modified carbon fiber, deionized water, pentaerythritol stearate, and sodium dodecylaminopropionate is 34.1-34.5:2.2-2.4:3.2-3.6:195-206:1.3-1.5:1.6-2.

0.

9. The method of enhancing the oxidation resistance of carbon-carbon composite materials by using titanium boride according to claim 7, characterized in that: The post-treatment step is to press the mixture under the conditions of a pressure of 6.3-6.7MPa and a temperature of 162-167°C for 3.8-4.3h. After the pressing, a molded product is obtained. The molded product is placed in an argon atmosphere, heated to 1250-1340°C at a rate of 12-14°C / min, and kept warm for 32-37min. After the insulation is completed, the temperature is increased to 1900-2050°C at a rate of 9.5-10.5°C / min, and kept warm for 16-25min. After the insulation is completed, the temperature is increased to 2410-2450°C at a rate of 5.8-6.2°C / min, and kept warm for 1.3-2.0h. After the insulation is completed, the temperature is naturally reduced to room temperature to obtain a carbon-carbon composite material.

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