Preparation Process of Phenolic-Impregnated Carbon Fiber Rods for C / SiC Composites

Abstract

The present invention relates to the field of composite materials, and specifically to a preparation process for phenolic-impregnated carbon fiber rods used in C / SiC composite materials, aiming to solve the problems that existing carbon fiber prepreg materials have weak interfacial bonding force between carbon fibers and impregnated resins, are prone to internal defects and residual stresses, and have a low char yield of the impregnated resin, resulting in poor density and strength, and affecting the overall performance of the composite materials. This preparation process uses a high-carbon boron-containing crosslinked phenolic resin to coat epoxy-modified carbon fibers, achieving uniform distribution and full penetration of the resin on the carbon fibers, improving the mechanical properties and thermal stability of the composite materials, significantly improving the overall performance of C / SiC composite materials, enabling them to meet the application requirements under high-precision and high-temperature environments. Moreover, this process is simple, easy to operate, and has a low cost, providing strong support for the industrial production of C / SiC composite materials.

Description

Technical Field

[0001] The present invention relates to the field of composite materials, and specifically to a preparation process for phenolic impregnated carbon fiber rods used for C / SiC composite materials. Background Art

[0002] Carbon fiber reinforced silicon carbide (C / SiC) composite materials combine the advantages of carbon fibers and silicon carbide ceramics, and have the advantages of low density, high specific strength, high specific modulus, high temperature resistance, oxidation resistance, good thermal stability, and wear resistance, etc. They show great application potential in the fields of aerospace thermal protection systems, space optical systems, braking systems, high-temperature heat exchange, engine blades, etc.

[0003] The preparation process of C / SiC composite materials is as follows: First, carbon fibers are impregnated in resin to form carbon fiber prepreg materials. Then, the carbon fiber prepreg materials are carbonized at high temperature. The resin is gradually converted into carbon and infiltrated into the carbon fibers during the multi-stage pyrolysis process, and finally combined with the subsequent silicon infiltration process to form SiC continuous phase crystals in the carbon matrix, thus constructing C / SiC composite materials.

[0004] Therefore, the properties of carbon fiber prepreg materials play a key role in the overall properties of C / SiC composite materials. However, due to the weak interfacial bonding force between carbon fibers and impregnated resin, it is difficult to form a high-density and uniform resin coating on their surfaces, and internal defects and residual stresses are likely to occur. Moreover, the existing impregnated resins have a low carbon residue rate at high temperature, resulting in a large loss of carbon content during the high-temperature treatment process of the composite materials, and further leading to poor density and strength, affecting the overall properties of the composite materials.

[0005] Therefore, it is of great significance to develop a preparation process for phenolic impregnated carbon fiber rods used for C / SiC composite materials. Summary of the Invention

[0006] In order to overcome the above technical problems, the purpose of the present invention is to provide a preparation process for phenolic impregnated carbon fiber rods used for C / SiC composite materials, which solves the problems that the existing carbon fiber prepreg materials are prone to internal defects and residual stresses due to the weak interfacial bonding force between carbon fibers and impregnated resin, and the impregnated resin has a low carbon residue rate at high temperature, resulting in poor density and strength, and affecting the overall properties of the composite materials.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A preparation process for phenolic impregnated carbon fiber rods used for C / SiC composite materials includes the following steps:

[0009] Step 1: Weigh 5-25 parts by weight of high-carbon boron-containing crosslinked phenolic resin, 3-11 parts of epoxy-modified carbon fiber, and 100 parts of absolute ethanol, and set aside.

[0010] Step 2: Add the high-carbon boron-containing crosslinked phenolic resin and absolute ethanol into a mixer, and stir and mix for 20-30 min under the conditions of a temperature of 25-30 °C and a stirring rate of 200-300 r / min to obtain an impregnating material.

[0011] Step 3: Add the impregnating material into an impregnation tank, then immerse the epoxy-modified carbon fiber in the impregnating material for 20-40 min, then take it out and place it in a bar model, dry it for 30-40 min under the condition of a temperature of 50-55 °C, then raise the temperature to 90-95 °C and continue to dry for 30-40 min, then raise the temperature to 120-130 °C and continue to dry for 30-40 min, then raise the temperature to 170-180 °C and continue to dry for 1-1.5 h, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composite materials.

[0012] As a further scheme of the present invention: The high-carbon boron-containing crosslinked phenolic resin is prepared by the following steps:

[0013] Step A1: Add phenol, boric acid, and toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas guide tube, introduce nitrogen protection, stir and react for 10-15 min under the conditions of a temperature of 25-30 °C and a stirring rate of 200-300 r / min, then raise the temperature to 150-160 °C and continue to stir and react for 3-4 h, then raise the temperature to 180-190 °C and continue to stir and react for 2-3 h. After the reaction is completed, cool the reaction product to room temperature, and then remove the solvent by rotary evaporation to obtain a triphenyl borate monomer.

[0014] Step A2: Add phenol, naphthol, the triphenyl borate monomer, and a formaldehyde solution into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a constant-pressure dropping funnel, stir and react for 10-15 min under the conditions of a temperature of 25-30 °C and a stirring rate of 200-300 r / min, then gradually dropwise add a sodium hydroxide solution while stirring until the pH is 9-10, control the dropping rate to be 1-2 drops / s. After the dropping is completed, raise the temperature to 50-55 °C and continue to stir and react for 1-2 h, then raise the temperature to 95-100 °C and continue to stir and react for 3-5 h, then add ethylene glycol diglycidyl ether and continue to stir and react for 1-2 h. After the reaction is completed, cool the reaction product to room temperature, then adjust it to pH 7 with a hydrochloric acid solution, and then remove the solvent by rotary evaporation to obtain a high-carbon boron-containing crosslinked phenolic resin.

[0015] As a further solution of the present invention: the dosage ratio of phenol, boric acid and toluene in step A1 is 30-35 mmol: 10 mmol: 40-50 mL.

[0016] As a further solution of the present invention: the dosage ratio of phenol, naphthol, triphenyl borate monomer, formaldehyde solution and ethylene glycol diglycidyl ether in step A2 is 8-10 g: 3-6 g: 2.2-3.6 g: 80-85 mL: 0.7-2.1 g.

[0017] As a further solution of the present invention: the mass fraction of the formaldehyde solution in step A2 is 37%; the mass fraction of the sodium hydroxide solution is 35-40%; the mass fraction of the hydrochloric acid solution is 20-22%.

[0018] As a further solution of the present invention: the epoxy modified carbon fiber is prepared by the following steps:

[0019] Step B1: Place the carbon fiber in a tube furnace, then heat it to 400-420 °C at a heating rate of 5-7 °C / min, then keep it at a constant temperature and calcine for 1-2 h, then cool it with the furnace, then add it to the hydrogen peroxide solution, then perform ultrasonic treatment for 2-3 h under the condition that the ultrasonic frequency is 30-40 kHz, then perform vacuum filtration, wash the filter cake with absolute ethanol and distilled water 3-5 times in sequence, then place it in a vacuum drying oven and dry it for 3-5 h at a temperature of 60-65 °C to obtain degummed oxidized carbon fiber;

[0020] Step B2: Add the degummed oxidized carbon fiber, silane coupling agent KH-560, deionized water and absolute ethanol to a three-necked flask equipped with a stirrer and a thermometer, perform ultrasonic dispersion for 20-30 min under the condition that the ultrasonic frequency is 30-40 kHz, then stir and react for 20-30 min under the conditions of a temperature of 25-30 °C and a stirring rate of 200-300 r / min, then continue to stir and react for 4-5 h under the condition of heating to 60-65 °C. After the reaction is completed, cool the reaction product to room temperature, then perform vacuum filtration, wash the filter cake with distilled water 3-5 times, then place it in a vacuum drying oven and dry it for 3-5 h at a temperature of 60-65 °C to obtain epoxy modified carbon fiber.

[0021] As a further solution of the present invention: the dosage ratio of the carbon fiber and the hydrogen peroxide solution in step B1 is 2 g: 20-25 mL.

[0022] As a further solution of the present invention: the carbon fiber in step B1 is Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm; the mass fraction of the hydrogen peroxide solution is 15-25%.

[0023] As a further solution of the present invention: the dosage ratio of the degummed oxidized carbon fiber, silane coupling agent KH-560, deionized water and absolute ethanol in step B2 is 5 g: 1.3-3.9 g: 85-90 mL: 10-12 mL.

[0024] Advantages of the present invention:

[0025] The preparation process of the phenolic impregnated carbon fiber rod for C / SiC composite material of the present invention is as follows: by adding high-carbon boron-containing cross-linked phenolic resin and absolute ethanol into a mixer and stirring and mixing to obtain an impregnating material, adding the impregnating material into an impregnation tank, then impregnating epoxy-modified carbon fiber into the impregnating material, and then taking it out and placing it in a rod model for curing to obtain a phenolic impregnated carbon fiber rod for C / SiC composite material; in this preparation process, the epoxy-modified carbon fiber is coated with high-carbon boron-containing cross-linked phenolic resin, realizing the uniform distribution and full penetration of the resin on the carbon fiber, improving the mechanical properties and thermal stability of the composite material, being able to significantly improve the overall performance of the C / SiC composite material, enabling the C / SiC composite material to meet the application requirements under high-precision and high-temperature environments, expanding its scope of application, and moreover, this process is simple, easy to operate, and has a low cost, providing strong support for the industrial production of C / SiC composite materials;

[0026] During the preparation of the phenolic impregnated carbon fiber rod, a high-carbon boron-containing cross-linked phenolic resin is first prepared. First, phenol and boric acid react, and the phenolic hydroxyl group on phenol and the boric acid group on boric acid react to form a borate ester structure while introducing a phenyl group to obtain a triphenyl borate monomer. Then, using phenol, naphthol, triphenyl borate monomer and formaldehyde as polymerization monomers, a polycondensation reaction is carried out under alkaline conditions to form a phenolic resin structure, and the hydroxyl group in the phenolic resin structure reacts with the epoxy group in ethylene glycol diglycidyl ether to realize the cross-linking between phenolic resin polymers, obtaining a high-carbon boron-containing cross-linked phenolic resin; by introducing a naphthalene ring, the carbon content of the molecular structure of this high-carbon boron-containing cross-linked phenolic resin is increased. Introducing boron atoms can replace some C-O bonds with relatively weak bond energy with B-O-C bonds with large bond energy, improving thermal stability, reducing high-temperature decomposition, and at the same time generating a boron oxide protective layer at high temperature to inhibit oxidation, and forming a branched structure. Under the combined action of ethylene glycol diglycidyl ether, the cross-linking density is significantly increased, enabling it to uniformly and densely coat the carbon fiber, forming a strong interfacial bond, improving the mechanical properties of the composite material, and inhibiting decomposition, so that this phenolic resin has a high char yield at high temperature;

[0027] In the process of preparing phenolic impregnated carbon fiber rods, an epoxy modified carbon fiber was also prepared. First, the surface impurities were removed by calcination treatment, and then a large number of oxygen-containing active groups were grafted after hydrogen peroxide treatment to obtain degummed oxidized carbon fiber. Then, the degummed oxidized carbon fiber was reacted with silane coupling agent KH-560. After the siloxane on the silane coupling agent KH-560 was hydrolyzed to form silanol and grafted onto the surface of the degummed oxidized carbon fiber, a large number of epoxy groups were introduced to obtain epoxy modified carbon fiber. The modified carbon fiber has good compatibility with the high-carbon boron-containing crosslinked phenolic resin, enabling the carbon fiber to be evenly distributed in the high-carbon boron-containing crosslinked phenolic resin, improving the overall quality and reliability of the rods. Moreover, the epoxy groups react chemically with the hydroxyl groups in the high-carbon boron-containing crosslinked phenolic resin, connecting the two in the form of chemical bonds and forming a strong interfacial bond. This interfacial bond can effectively transfer stress and improve the mechanical properties of the composite material. Detailed implementation mode

[0028] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0029] Example 1: This example is a preparation process for phenolic impregnated carbon fiber rods for C / SiC composite materials, including the following steps:

[0030] Step S1: Add 30 mmol of phenol, 10 mmol of boric acid, and 40 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas guide tube, introduce nitrogen for protection, stir and react for 10 min under the conditions of a temperature of 25 °C and a stirring rate of 200 r / min, then continue to stir and react for 3 h under the condition of raising the temperature to 150 °C, and then continue to stir and react for 2 h under the condition of raising the temperature to 180 °C. After the reaction is completed, cool the reaction product to room temperature, and then remove the solvent by rotary evaporation to obtain the triphenyl borate monomer;

[0031] Step S2: Add 8 g of phenol, 3 g of naphthol, 2.2 g of triphenyl borate monomer, and 80 mL of 37% formaldehyde solution by mass to a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Stir and react for 10 min at a temperature of 25°C and a stirring rate of 200 r / min. Then, while stirring, gradually add 35% sodium hydroxide solution by mass dropwise until the pH reaches 9, controlling the dropping rate at 1 drop / s. After the dropping is complete, raise the temperature to 50°C and continue stirring and reacting for 1 h. Then, raise the temperature to 95°C and continue stirring and reacting for 3 h. Then, add 0.7 g of ethylene glycol diglycidyl ether and continue stirring and reacting for 1 h. After the reaction is completed, cool the reaction product to room temperature. Then, adjust the pH to 7 with 20% hydrochloric acid solution by mass. Then, rotate and evaporate to remove the solvent to obtain a high-carbon boron-containing crosslinked phenolic resin;

[0032] Step S3: Place 2 g of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm in a tube furnace. Then, raise the temperature to 400°C at a heating rate of 5°C / min. Then, keep the temperature constant and calcine for 1 h. Then, cool with the furnace. Then, add it to 20 mL of 15% hydrogen peroxide solution by mass. Then, perform ultrasonic treatment for 2 h under the condition of an ultrasonic frequency of 30 kHz. Then, perform vacuum filtration. Wash the filter cake with anhydrous ethanol and distilled water three times in sequence. Then, place it in a vacuum drying oven and dry for 3 h at a temperature of 60°C to obtain degummed oxidized carbon fiber;

[0033] Step S4: Add 5 g of degummed oxidized carbon fiber, 1.3 g of silane coupling agent KH-560, 85 mL of deionized water, and 10 mL of anhydrous ethanol to a three-necked flask equipped with a stirrer and a thermometer. Perform ultrasonic dispersion for 20 min under the condition of an ultrasonic frequency of 30 kHz. Then, stir and react for 20 min at a temperature of 25°C and a stirring rate of 200 r / min. Then, raise the temperature to 60°C and continue stirring and reacting for 4 h. After the reaction is completed, cool the reaction product to room temperature. Then, perform vacuum filtration. Wash the filter cake with distilled water three times. Then, place it in a vacuum drying oven and dry for 3 h at a temperature of 60°C to obtain epoxy-modified carbon fiber;

[0034] Step S5: Weigh 5 parts of high-carbon boron-containing crosslinked phenolic resin, 3 parts of epoxy-modified carbon fiber, and 100 parts of anhydrous ethanol by weight for standby;

[0035] Step S6: Add the high-carbon boron-containing crosslinked phenolic resin and anhydrous ethanol to a mixer. Stir and mix for 20 min at a temperature of 25°C and a stirring rate of 200 r / min to obtain an impregnating resin;

[0036] Step S7: Add the sized material into the impregnation tank, then immerse the epoxy-modified carbon fiber in the sized material for 20 min, then take it out and place it in a bar model, dry it at a temperature of 50°C for 30 min, then raise the temperature to 90°C and continue to dry for 30 min, then raise the temperature to 120°C and continue to dry for 30 min, then raise the temperature to 170°C and continue to dry for 1 h, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composites.

[0037] Example 2: This example is a preparation process of a phenolic-impregnated carbon fiber bar for C / SiC composites, including the following steps:

[0038] Step S1: Add 32 mmol of phenol, 10 mmol of boric acid, and 45 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas guide tube, introduce nitrogen protection, stir and react at a temperature of 28°C and a stirring rate of 250 r / min for 12 min, then raise the temperature to 155°C and continue to stir and react for 3.5 h, then raise the temperature to 185°C and continue to stir and react for 2.5 h. After the reaction is completed, cool the reaction product to room temperature, and then rotary evaporate to remove the solvent to obtain a triphenyl borate monomer.

[0039] Step S2: Add 9 g of phenol, 4.5 g of naphthol, 2.9 g of triphenyl borate monomer, and 82 mL of a 37% mass fraction formaldehyde solution into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a constant pressure dropping funnel, stir and react at a temperature of 28°C and a stirring rate of 250 r / min for 12 min, then gradually add a 38% mass fraction sodium hydroxide solution dropwise while stirring until the pH is 9.5, control the dropping rate at 1 drop / s. After the dropping is completed, raise the temperature to 52°C and continue to stir and react for 1.5 h, then raise the temperature to 98°C and continue to stir and react for 4 h, then add 1.4 g of ethylene glycol diglycidyl ether and continue to stir and react for 1.5 h. After the reaction is completed, cool the reaction product to room temperature, then adjust it to pH 7 with a 21% mass fraction hydrochloric acid solution, and then rotary evaporate to remove the solvent to obtain a high-carbon boron-containing crosslinked phenolic resin.

[0040] Step S3: Place 2 g of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm into a tube furnace. Then, heat it to 410 °C at a heating rate of 6 °C / min, followed by isothermal calcination for 1.5 h. After that, cool it down with the furnace. Then, add it to 22 mL of hydrogen peroxide solution with a mass fraction of 20%. Next, perform ultrasonic treatment for 2.5 h under the condition that the ultrasonic frequency is 35 kHz. Then, carry out vacuum filtration, wash the filter cake 4 times with anhydrous ethanol and distilled water in sequence. After that, place it in a vacuum drying oven and dry it for 4 h at a temperature of 62 °C to obtain degummed oxidized carbon fiber;

[0041] Step S4: Add 5 g of degummed oxidized carbon fiber, 2.6 g of silane coupling agent KH-560, 88 mL of deionized water, and 11 mL of anhydrous ethanol into a three-necked flask equipped with a stirrer and a thermometer. Carry out ultrasonic dispersion for 25 min under the condition that the ultrasonic frequency is 35 kHz. Then, carry out stirring reaction for 25 min at a temperature of 28 °C and a stirring rate of 250 r / min. After that, continue the stirring reaction for 4.5 h at a temperature of 62 °C. After the reaction ends, cool the reaction product to room temperature. Then, carry out vacuum filtration, wash the filter cake 4 times with distilled water. After that, place it in a vacuum drying oven and dry it for 4 h at a temperature of 62 °C to obtain epoxy-modified carbon fiber;

[0042] Step S5: Weigh 15 parts of high-carbon boron-containing crosslinked phenolic resin, 7 parts of epoxy-modified carbon fiber, and 100 parts of anhydrous ethanol by weight for standby;

[0043] Step S6: Add the high-carbon boron-containing crosslinked phenolic resin and anhydrous ethanol into a mixer and stir and mix for 25 min at a temperature of 28 °C and a stirring rate of 250 r / min to obtain an impregnating resin;

[0044] Step S7: Add the impregnating resin into an impregnation tank. Then, immerse the epoxy-modified carbon fiber in the impregnating resin for 30 min. After that, take it out and place it in a bar model, dry it for 35 min at a temperature of 52 °C, then continue to dry it for 35 min at a temperature of 92 °C, then continue to dry it for 35 min at a temperature of 125 °C, then continue to dry it for 1 h at a temperature of 175 °C, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composite materials.

[0045] Example 3: This example is a preparation process of a phenolic-impregnated carbon fiber bar for C / SiC composite materials, including the following steps:

[0046] Step S1: Add 35 mmol of phenol, 10 mmol of boric acid, and 50 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min. Then, raise the temperature to 160 °C and continue to stir and react for 4 h. Subsequently, raise the temperature to 190 °C and continue to stir and react for 3 h. After the reaction is completed, cool the reaction product to room temperature, and then remove the solvent by rotary evaporation to obtain the triphenyl borate monomer;

[0047] Step S2: Add 10 g of phenol, 6 g of naphthol, 3.6 g of the triphenyl borate monomer, and 85 mL of a 37% mass fraction formaldehyde solution into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min. Then, gradually add a 40% mass fraction sodium hydroxide solution drop by drop while stirring until the pH is 10, controlling the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to 55 °C and continue to stir and react for 2 h. Subsequently, raise the temperature to 100 °C and continue to stir and react for 5 h. Then, add 2.1 g of ethylene glycol diglycidyl ether and continue to stir and react for 2 h. After the reaction is completed, cool the reaction product to room temperature, and then adjust the pH to 7 with a 22% mass fraction hydrochloric acid solution. Then, remove the solvent by rotary evaporation to obtain the high-carbon boron-containing crosslinked phenolic resin;

[0048] Step S3: Place 2 g of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm into a tubular furnace. Then, raise the temperature to 420 °C at a heating rate of 7 °C / min, then keep it at a constant temperature and calcine for 2 h, and then cool it with the furnace. Then, add it into 25 mL of a 25% mass fraction hydrogen peroxide solution, and then carry out ultrasonic treatment for 3 h under the condition of an ultrasonic frequency of 40 kHz. Then, carry out vacuum filtration, wash the filter cake successively with absolute ethanol and distilled water 5 times, and then place it in a vacuum drying oven and dry it at a temperature of 65 °C for 5 h to obtain the degummed oxidized carbon fiber;

[0049] Step S4: Add 5 g of the degummed oxidized carbon fiber, 3.9 g of the silane coupling agent KH-560, 90 mL of deionized water, and 12 mL of absolute ethanol into a three-necked flask equipped with a stirrer and a thermometer. Carry out ultrasonic dispersion for 30 min under the condition of an ultrasonic frequency of 40 kHz. Then, stir and react for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min. Then, raise the temperature to 65 °C and continue to stir and react for 5 h. After the reaction is completed, cool the reaction product to room temperature, then carry out vacuum filtration, wash the filter cake with distilled water 5 times, and then place it in a vacuum drying oven and dry it at a temperature of 65 °C for 5 h to obtain the epoxy-modified carbon fiber;

[0050] Step S5: Weigh 25 parts of high-carbon boron-containing crosslinked phenolic resin, 11 parts of epoxy-modified carbon fiber, and 100 parts of absolute ethanol by weight, and set aside.

[0051] Step S6: Add the high-carbon boron-containing crosslinked phenolic resin and absolute ethanol to a mixer, and stir and mix for 30 min under the conditions of a temperature of 30°C and a stirring rate of 300 r / min to obtain an impregnating material.

[0052] Step S7: Add the impregnating material into an impregnation tank, then immerse the epoxy-modified carbon fiber in the impregnating material for 40 min, then take it out and place it in a bar model, dry it for 40 min under the condition of a temperature of 55°C, then raise the temperature to 95°C and continue to dry for 40 min, then raise the temperature to 130°C and continue to dry for 40 min, then raise the temperature to 180°C and continue to dry for 1.5 h, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composite materials.

[0053] Comparative Example 1:

[0054] This comparative example is a preparation process of a phenolic-impregnated carbon fiber bar for C / SiC composite materials, including the following steps:

[0055] Step S1: Add 10 g of phenol and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube, and a constant-pressure dropping funnel, stir and react for 15 min under the conditions of a temperature of 30°C and a stirring rate of 300 r / min, then dropwise add a sodium hydroxide solution with a mass fraction of 40% drop by drop while stirring until the pH is 10, control the dropping rate at 2 drops / s, after dropping, raise the temperature to 55°C and continue to stir and react for 2 h, then raise the temperature to 100°C and continue to stir and react for 5 h, after the reaction is completed, cool the reaction product to room temperature, then adjust it to pH 7 with a hydrochloric acid solution with a mass fraction of 22%, and then remove the solvent by rotary evaporation to obtain phenolic resin.

[0056] Step S2: Weigh 25 parts of phenolic resin, 11 parts of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm, and 100 parts of absolute ethanol by weight, and set aside.

[0057] Step S3: Add the phenolic resin and absolute ethanol to a mixer, and stir and mix for 30 min under the conditions of a temperature of 30°C and a stirring rate of 300 r / min to obtain an impregnating material.

[0058] Step S4: Add the impregnating material into the impregnation tank, then immerse the Zhongfu Shenying SYT49S-12K carbon fiber in the impregnating material for 40 minutes, then take it out and place it in the bar model, dry it at a temperature of 55°C for 40 minutes, then raise the temperature to 95°C and continue drying for 40 minutes, then raise the temperature to 130°C and continue drying for 40 minutes, then raise the temperature to 180°C and continue drying for 1.5 hours, and then cool it to room temperature to obtain the phenolic impregnated carbon fiber bar for C / SiC composite materials.

[0059] Comparative Example 2:

[0060] This comparative example is a preparation process of a phenolic impregnated carbon fiber bar for C / SiC composite materials, including the following steps:

[0061] Step S1: Add 10 g of phenol, 6 g of naphthol, and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Stir and react at a temperature of 30°C and a stirring rate of 300 r / min for 15 minutes, then gradually add a sodium hydroxide solution with a mass fraction of 40% dropwise while stirring until the pH is 10, control the dropping rate at 2 drops / s. After dropping, raise the temperature to 55°C and continue stirring and reacting for 2 hours, then raise the temperature to 100°C and continue stirring and reacting for 5 hours. After the reaction ends, cool the reaction product to room temperature, then adjust it to pH 7 with a hydrochloric acid solution with a mass fraction of 22%, and then rotate and evaporate to remove the solvent to obtain a high-carbon phenolic resin;

[0062] Step S2: Weigh 25 parts of high-carbon phenolic resin, 11 parts of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm, and 100 parts of absolute ethanol according to weight, and set aside;

[0063] Step S3: Add the high-carbon phenolic resin and absolute ethanol into a mixer, stir and mix at a temperature of 30°C and a stirring rate of 300 r / min for 30 minutes to obtain the impregnating material;

[0064] Step S4: Add the impregnating material into the impregnation tank, then immerse the Zhongfu Shenying SYT49S-12K carbon fiber in the impregnating material for 40 minutes, then take it out and place it in the bar model, dry it at a temperature of 55°C for 40 minutes, then raise the temperature to 95°C and continue drying for 40 minutes, then raise the temperature to 130°C and continue drying for 40 minutes, then raise the temperature to 180°C and continue drying for 1.5 hours, and then cool it to room temperature to obtain the phenolic impregnated carbon fiber bar for C / SiC composite materials.

[0065] Comparative Example 3:

[0066] This comparative example is a preparation process of phenolic impregnated carbon fiber rods for C / SiC composites, including the following steps:

[0067] Step S1: Add 35 mmol of phenol, 10 mmol of boric acid, and 50 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min. Then, raise the temperature to 160 °C and continue to stir and react for 4 h. After that, raise the temperature to 190 °C and continue to stir and react for 3 h. After the reaction ends, cool the reaction product to room temperature, and then rotate and evaporate to remove the solvent to obtain triphenyl borate monomer;

[0068] Step S2: Add 10 g of phenol, 6 g of naphthol, 3.6 g of triphenyl borate monomer, and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min. Then, gradually add a sodium hydroxide solution with a mass fraction of 40% drop by drop while stirring until the pH is 10, controlling the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to 55 °C and continue to stir and react for 2 h. After that, raise the temperature to 100 °C and continue to stir and react for 5 h. After the reaction ends, cool the reaction product to room temperature, and then adjust the pH to 7 with a hydrochloric acid solution with a mass fraction of 22%. Then, rotate and evaporate to remove the solvent to obtain a high-carbon boron-containing phenolic resin;

[0069] Step S3: Weigh 25 parts of high-carbon boron-containing phenolic resin, 11 parts of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm, and 100 parts of absolute ethanol according to weight, and set aside;

[0070] Step S4: Add the high-carbon boron-containing phenolic resin and absolute ethanol into a mixer, and stir and mix for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min to obtain an impregnating material;

[0071] Step S5: Add the impregnating material into an impregnation tank, then immerse the Zhongfu Shenying SYT49S-12K carbon fiber in the impregnating material for 40 min, then take it out and place it in a rod model, dry it for 40 min under the condition of a temperature of 55 °C, then raise the temperature to 95 °C and continue to dry for 40 min, then raise the temperature to 130 °C and continue to dry for 40 min, then raise the temperature to 180 °C and continue to dry for 1.5 h, and then cool to room temperature to obtain phenolic impregnated carbon fiber rods for C / SiC composites.

[0072] Comparative Example 4:

[0073] This comparative example is a preparation process of phenolic impregnated carbon fiber rods for C / SiC composites, including the following steps:

[0074] Step S1: Add 35 mmol of phenol, 10 mmol of boric acid, and 50 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen protection and stir and react at a temperature of 30 °C and a stirring rate of 300 r / min for 15 min. Then, raise the temperature to 160 °C and continue to stir and react for 4 h. Then, raise the temperature to 190 °C and continue to stir and react for 3 h. After the reaction ends, cool the reaction product to room temperature, and then remove the solvent by rotary evaporation to obtain triphenyl borate monomer;

[0075] Step S2: Add 10 g of phenol, 6 g of naphthol, 3.6 g of triphenyl borate monomer, and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Stir and react at a temperature of 30 °C and a stirring rate of 300 r / min for 15 min. Then, gradually add a sodium hydroxide solution with a mass fraction of 40% dropwise while stirring until the pH is 10, control the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to 55 °C and continue to stir and react for 2 h. Then, raise the temperature to 100 °C and continue to stir and react for 5 h. Then, add 2.1 g of ethylene glycol diglycidyl ether and continue to stir and react for 2 h. After the reaction ends, cool the reaction product to room temperature, and then adjust the pH to 7 with a hydrochloric acid solution with a mass fraction of 22%. Then, remove the solvent by rotary evaporation to obtain a high-carbon boron-containing crosslinked phenolic resin;

[0076] Step S3: Weigh 25 parts of high-carbon boron-containing crosslinked phenolic resin, 11 parts of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm, and 100 parts of absolute ethanol, and set aside;

[0077] Step S4: Add the high-carbon boron-containing crosslinked phenolic resin and absolute ethanol into a mixer and stir and mix at a temperature of 30 °C and a stirring rate of 300 r / min for 30 min to obtain an impregnating material;

[0078] Step S5: Add the impregnating material into an impregnation tank, then immerse the Zhongfu Shenying SYT49S-12K carbon fiber in the impregnating material for 40 min, then take it out and place it in a rod model, dry it at a temperature of 55 °C for 40 min, then raise the temperature to 95 °C and continue to dry for 40 min, then raise the temperature to 130 °C and continue to dry for 40 min, then raise the temperature to 180 °C and continue to dry for 1.5 h, and then cool to room temperature to obtain phenolic impregnated carbon fiber rods for C / SiC composites.

[0079] Comparative Example 5:

[0080] This comparative example is a preparation process of a phenolic resin impregnated carbon fiber rod for C / SiC composites, including the following steps:

[0081] Step S1: Add 35 mmol of phenol, 10 mmol of boric acid, and 50 mL of toluene into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection, stir and react at a temperature of 30 °C and a stirring rate of 300 r / min for 15 min, then raise the temperature to 160 °C and continue to stir and react for 4 h, and then raise the temperature to 190 °C and continue to stir and react for 3 h. After the reaction is completed, cool the reaction product to room temperature, and then rotate and evaporate to remove the solvent to obtain a triphenyl borate monomer;

[0082] Step S2: Add 10 g of phenol, 6 g of naphthol, 3.6 g of triphenyl borate monomer, and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Stir and react at a temperature of 30 °C and a stirring rate of 300 r / min for 15 min, then gradually add a sodium hydroxide solution with a mass fraction of 40% dropwise while stirring until the pH is 10, control the dropping rate at 2 drops / s. After the dropping is completed, raise the temperature to 55 °C and continue to stir and react for 2 h, then raise the temperature to 100 °C and continue to stir and react for 5 h, and then add 2.1 g of ethylene glycol diglycidyl ether and continue to stir and react for 2 h. After the reaction is completed, cool the reaction product to room temperature, then adjust the pH to 7 with a hydrochloric acid solution with a mass fraction of 22%, and then rotate and evaporate to remove the solvent to obtain a high-carbon boron-containing cross-linked phenolic resin;

[0083] Step S3: Place 2 g of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm in a tube furnace, then raise the temperature to 420 °C at a heating rate of 7 °C / min, then keep it at a constant temperature and calcine for 2 h, then cool it with the furnace, then add it to 25 mL of hydrogen peroxide solution with a mass fraction of 25%, then carry out ultrasonic treatment for 3 h under the condition of an ultrasonic frequency of 40 kHz, then carry out vacuum filtration, wash the filter cake with absolute ethanol and distilled water 5 times in sequence, and then place it in a vacuum drying oven and dry it at a temperature of 65 °C for 5 h to obtain degummed oxidized carbon fiber;

[0084] Step S4: Weigh 25 parts of high-carbon boron-containing cross-linked phenolic resin, 11 parts of degummed oxidized carbon fiber, and 100 parts of absolute ethanol according to weight, and set aside;

[0085] Step S5: Add high-carbon boron-containing crosslinked phenolic resin and absolute ethanol into a mixer, and stir and mix for 30 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min to obtain an impregnating material;

[0086] Step S6: Add the impregnating material into an impregnation tank, then immerse the sized and oxidized carbon fiber in the impregnating material for 40 min, then take it out and place it in a bar model, dry it for 40 min under the condition of a temperature of 55 °C, then raise the temperature to 95 °C and continue to dry for 40 min, then raise the temperature to 130 °C and continue to dry for 40 min, then raise the temperature to 180 °C and continue to dry for 1.5 h, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composites.

[0087] Comparative Example 6:

[0088] This comparative example is a preparation process of a phenolic-impregnated carbon fiber bar for C / SiC composites, including the following steps:

[0089] Step S1: Add 10 g of phenol and 85 mL of formaldehyde solution with a mass fraction of 37% into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe and a constant-pressure dropping funnel, stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 300 r / min, then gradually add a sodium hydroxide solution with a mass fraction of 40% dropwise while stirring until the pH is 10, control the dropping rate at 2 drops / s, after the dropping is completed, raise the temperature to 55 °C and continue to stir and react for 2 h, then raise the temperature to 100 °C and continue to stir and react for 5 h, after the reaction is completed, cool the reaction product to room temperature, then adjust it to pH 7 with a hydrochloric acid solution with a mass fraction of 22%, and then remove the solvent by rotary evaporation to obtain phenolic resin;

[0090] Step S2: Place 2 g of Zhongfu Shenying SYT49S-12K carbon fiber with a length of 25 mm in a tubular furnace, then raise the temperature to 420 °C at a heating rate of 7 °C / min, then keep it at a constant temperature and calcine for 2 h, then cool it with the furnace, then add it into 25 mL of hydrogen peroxide solution with a mass fraction of 25%, then carry out ultrasonic treatment for 3 h under the condition of an ultrasonic frequency of 40 kHz, then carry out vacuum filtration, wash the filter cake with absolute ethanol and distilled water 5 times in sequence, and then place it in a vacuum drying oven and dry it for 5 h under the condition of a temperature of 65 °C to obtain sized and oxidized carbon fiber;

[0091] Step S3: Add 5 g of degummed oxidized carbon fiber, 3.9 g of silane coupling agent KH-560, 90 mL of deionized water, and 12 mL of absolute ethanol into a three-necked flask equipped with a stirrer and a thermometer. Ultrasonically disperse for 30 min under the condition of an ultrasonic frequency of 40 kHz. Then, stir and react for 30 min at a temperature of 30 °C and a stirring rate of 300 r / min. After that, continue to stir and react for 5 h under the condition of raising the temperature to 65 °C. After the reaction ends, cool the reaction product to room temperature. Then, perform vacuum filtration. Wash the filter cake 5 times with distilled water. After that, place it in a vacuum drying oven and dry for 5 h at a temperature of 65 °C to obtain epoxy-modified carbon fiber;

[0092] Step S4: Weigh 25 parts of phenolic resin, 11 parts of epoxy-modified carbon fiber, and 100 parts of absolute ethanol by weight and set aside;

[0093] Step S5: Add the phenolic resin and absolute ethanol into a mixer and stir and mix for 30 min at a temperature of 30 °C and a stirring rate of 300 r / min to obtain an impregnating resin;

[0094] Step S6: Add the impregnating resin into an impregnation tank. Then, immerse the epoxy-modified carbon fiber in the impregnating resin for 40 min. After that, take it out and place it in a bar model. Dry for 40 min at a temperature of 55 °C. Then, continue to dry for 40 min under the condition of raising the temperature to 95 °C. Then, continue to dry for 40 min under the condition of raising the temperature to 130 °C. Then, continue to dry for 1.5 h under the condition of raising the temperature to 180 °C. After that, cool to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composites.

[0095] Test the properties of the phenolic-impregnated carbon fiber bars for C / SiC composites in Examples 1-3 and Comparative Examples 1-6:

[0096] Test the tensile properties in accordance with GB / T-1447-2005;

[0097] Test the compressive properties in accordance with GB / T-1448-2005;

[0098] Use a NETZSCH STA 409 CD synchronous thermal analyzer to test the temperature and char yield when the mass of the sample decreases by 5% during heating under the conditions of a nitrogen environment with a flow rate of 25 mL / min and a heating rate of 10 °C / min starting from room temperature to 1000 °C.

[0099] 。

[0100] Referring to the data in the above table, by comparing Examples 1-3 and Comparative Examples 1-6, it can be known that the phenolic impregnated carbon fiber rod for C / SiC composite material of the present application has excellent mechanical properties, heat resistance and high residual carbon content.

[0101] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0102] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar ways to replace them. As long as they do not deviate from the invention or exceed the scope defined by this application, they should all fall within the protection scope of the present invention.

Claims

1. Preparation process of phenolic impregnated carbon fiber rods for C / SiC composites, characterized in that It includes the following steps: Step 1: Weigh 5-25 parts by weight of high-carbon boron-containing crosslinked phenolic resin, 3-11 parts of epoxy-modified carbon fiber, and 100 parts of absolute ethanol for standby; Step 2: Add the high-carbon boron-containing crosslinked phenolic resin and absolute ethanol into a mixer, and stir and mix for 20-30 min under the conditions of a temperature of 25-30 °C and a stirring rate of 200-300 r / min to obtain an impregnating resin; Step 3: Add the impregnating resin into an impregnation tank, then immerse the epoxy-modified carbon fiber in the impregnating resin for 20-40 min, then take it out and place it in a bar model, dry it for 30-40 min under the condition of a temperature of 50-55 °C, then raise the temperature to 90-95 °C and continue to dry for 30-40 min, then raise the temperature to 120-130 °C and continue to dry for 30-40 min, then raise the temperature to 170-180 °C and continue to dry for 1-1.5 h, and then cool it to room temperature to obtain a phenolic-impregnated carbon fiber bar for C / SiC composite materials; The high-carbon boron-containing crosslinked phenolic resin is prepared by the following steps: Step A1: Stir and react phenol, boric acid, and toluene. After the reaction ends, cool the reaction product, and then perform rotary evaporation to obtain a triphenyl borate monomer; the dosage ratio of phenol, boric acid, and toluene is 30-35 mmol: 10 mmol: 40-50 mL; Step A2: Stir and react phenol, naphthol, the triphenyl borate monomer, and a formaldehyde solution, then gradually add a sodium hydroxide solution drop by drop while stirring. After the addition is complete, continue to stir and react, then add ethylene glycol diglycidyl ether and continue to stir and react. After the reaction ends, cool the reaction product, then adjust the pH with a hydrochloric acid solution, and then perform rotary evaporation to obtain a high-carbon boron-containing crosslinked phenolic resin; the dosage ratio of phenol, naphthol, the triphenyl borate monomer, the formaldehyde solution, and ethylene glycol diglycidyl ether is 8-10 g: 3-6 g: 2.2-3.6 g: 80-85 mL: 0.7-2.1 g; the mass fraction of the formaldehyde solution is 37%; the mass fraction of the sodium hydroxide solution is 35-40%; the mass fraction of the hydrochloric acid solution is 20-22%.

2. The preparation process of the phenolic impregnated carbon fiber rod for C / SiC composite materials according to claim 1, characterized in that, The epoxy-modified carbon fiber is prepared by the following steps: Step B1: Place the carbon fiber in a tubular furnace for constant-temperature calcination, then cool it with the furnace, then add it to a hydrogen peroxide solution for ultrasonic treatment, then perform vacuum filtration, wash and dry the filter cake to obtain degummed oxidized carbon fiber; Step B2: Ultrasonically disperse the degummed oxidized carbon fiber, silane coupling agent KH-560, deionized water, and absolute ethanol, then perform a stirring reaction. After the reaction ends, cool the reaction product, then perform vacuum filtration, wash and dry the filter cake to obtain epoxy-modified carbon fiber.

3. The preparation process of the phenolic impregnated carbon fiber rod for C / SiC composite materials according to claim 2, characterized in that, In Step B1, the dosage ratio of the carbon fiber to the hydrogen peroxide solution is 2 g: 20-25 mL.

4. The preparation process of the phenolic resin impregnated carbon fiber rod for C / SiC composite materials according to claim 2, characterized in that, In Step B1, the carbon fiber is SYT49S-12K carbon fiber with a length of 25 mm; the mass fraction of the hydrogen peroxide solution is 15-25%.

5. The preparation process of the phenolic impregnated carbon fiber rod for C / SiC composite materials according to claim 2, characterized in that, The dosage ratio of the degummed oxidized carbon fiber, silane coupling agent KH-560, deionized water and absolute ethanol in step B2 is 5 g: 1.3 - 3.9 g: 85 - 90 mL: 10 - 12 mL.