C / c-sic composite material and method for manufacturing the same

Abstract

The application provides a near-zero expansion C / C-SiC composite material preparation method, which comprises the following steps: S1, graphene oxide is grafted on the surface of pitch carbon fiber; S2, the pitch carbon fiber obtained in S1 is woven into a three-dimensional quasi-isotropic pitch carbon fiber preform; S3, thermosetting resin, a curing agent and an organic solvent are uniformly mixed to prepare resin slurry, and then the pitch carbon fiber preform obtained in S2 is vacuum impregnated in the resin slurry, and then cured and pyrolyzed until the density of the pitch carbon fiber preform reaches 1.30-1.50 g / cm 3 , and a porous C / C composite material framework is prepared; and S4, the gradient porous C / C composite material framework prepared in S3 is subjected to reaction infiltration of silicon, and the C / C-SiC composite material is obtained. The method utilizes the graphene oxide transition layer formed by grafting graphene oxide on the surface of pitch carbon fiber, so that the carbon fiber can be protected from high-temperature corrosion of silicon, and the wettability with the resin can be obviously improved; the structure of the thermosetting resin impregnated and pyrolyzed carbon framework is controlled to be a gradient porous structure, so that the content of free silicon in the composite material after reaction infiltration is reduced; and the C / C-SiC composite material with excellent mechanical properties and near-zero expansion is obtained.

Description

Technical Field

[0001] This invention belongs to the field of structural and functional integrated composite material technology, specifically relating to a C / C-SiC composite material and its preparation method. Background Technology

[0002] Pitch-reinforced carbon-silicon carbide composites (C / C-SiC composites) integrate the excellent mechanical and thermal properties of carbon fibers with the excellent chemical and thermal stability of silicon carbide ceramic matrices. They possess superior properties such as low density, high specific strength, low coefficient of thermal expansion, high thermal conductivity, and good resistance to space radiation. They can well meet the application requirements of space optomechanical structural components, and have therefore become an ideal material for the next generation of space optomechanical structural components and one of the important development directions. They are the fourth generation of ideal optomechanical component materials after glass, metal, and SiC ceramic materials.

[0003] Near-zero expansion C / C-SiC composites are multi-component systems composed of pitch-based carbon fibers, a pyrolytic carbon transition layer, and a silicon carbide ceramic layer. The mesophase pitch-based carbon fibers and pyrolytic carbon possess negative coefficients of thermal expansion along the fiber axis, which can limit the expansion of the silicon carbide ceramic phase. Theoretically, near-zero expansion C / C-SiC composites can be obtained by controlling the fiber volume fraction and the structure of the pyrolytic carbon, as well as designing the braided structure. Unlike traditional C / C-SiC composites, the preparation of near-zero expansion C / C-SiC composites requires special structural design and fabrication processes to achieve near-zero in-plane and thickness-direction coefficients of thermal expansion.

[0004] Reactive infiltration is a common and important method for preparing C / C-SiC composites. This method offers advantages such as a short process flow, low manufacturing cost, and high density, making it a preferred method for high-temperature structural materials used in automobiles, high-speed rail, and aerospace applications. Reactive infiltration utilizes the capillary effect to infiltrate molten silicon into the pores of the carbon / ceramic composite, where it reacts with the carbon at high temperatures to form silicon carbide, achieving ceramicization. However, during reactive infiltration, the interface between the carbon fibers and pyrolytic carbon can become a channel for the infiltration of molten silicon. The infiltrated silicon reacts with the carbon fibers, damaging the surface structure and severely impairing the mechanical properties of the carbon fibers. Furthermore, due to the limited diffusion depth of silicon in solid pyrolytic carbon, silicon carbide is only formed on the surface of the pyrolytic carbon. This results in some silicon infiltrating into the pores of the composite material without a carbon source to react, remaining in the composite material as free silicon, further damaging the mechanical and physical properties of the composite material. Summary of the Invention

[0005] This invention aims to overcome the shortcomings of existing technologies and provides a near-zero expansion C / C-SiC composite material and its preparation method. The technical solution of this invention to solve the above-mentioned technical problems is as follows:

[0006] A method for preparing a C / C-SiC composite material includes the following steps:

[0007] S1 grafts graphene oxide onto the surface of pitch-carbon fiber;

[0008] S2 braids the pitch-carbon fiber obtained in S1 into a three-dimensional quasi-isotropic pitch-carbon fiber preform;

[0009] S3 involves uniformly mixing a thermosetting resin with a curing agent and an organic solvent to prepare a resin slurry. The pitch-carbon fiber preform obtained in S2 is then vacuum impregnated in the resin slurry, followed by curing and pyrolysis until the density of the pitch-carbon fiber preform reaches 1.30-1.50 g / cm³. 3 A porous C / C composite skeleton was fabricated.

[0010] S4 reacts and melts silicon into the gradient porous C / C composite skeleton obtained in S3 to obtain the C / C-SiC composite material; the carbon fibers in the pitch carbon fiber preform are perpendicular to each other in three directions, forming an orthogonal structure, and the edges of the pitch carbon fiber preform form an interlocking structure.

[0011] In the X direction, the volume fraction of the asphalt carbon fiber preform is 15-20 vol%.

[0012] In the Y direction, the volume fraction of the asphalt carbon fiber preform is 15-20 vol%.

[0013] The volume fraction of the pitch-carbon fiber preform in the Z direction is 8-12 vol%.

[0014] The C / C-SiC composite material has a planar coefficient of thermal expansion of approximately 0.03-0.46 ppm / K and a thickness coefficient of thermal expansion of approximately 0.18-0.69 ppm / K.

[0015] S1 involves using plasma to modify the surface of the pitch-carbon fiber, and then using a silane coupling agent grafting method to graft graphene oxide onto the surface of the carbon fiber.

[0016] The plasma treatment method uses one or more of the following plasmas: Ar, N2, and O2.

[0017] The plasma treatment method uses a discharge power of 200W-800W;

[0018] The plasma treatment method uses a processing time of 10s-100s.

[0019] S1 includes the steps of mixing an alcohol dispersion of graphene oxide and an alcohol solution of a silane coupling agent to obtain a coupling agent-modified graphene oxide dispersion, then impregnating the plasma-treated pitch carbon fiber in the coupling agent-modified graphene oxide dispersion, and finally removing and drying it.

[0020] In the alcohol dispersion of graphene oxide, the ratio of alcohol solvent to graphene oxide is 10 mL: 30-60 mg.

[0021] In the alcohol solution of the silane coupling agent, the mass fraction of the silane coupling agent is 2-5%;

[0022] In the modified graphene oxide dispersion of the coupling agent, the alcohol dispersion of graphene oxide and the alcohol solution of silane coupling agent are in a volume ratio of 10:1-5.

[0023] The silane coupling agent is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β(aminoethyl)-γ-aminopropyltriethoxysilane.

[0024] The process involves vacuum impregnating the pitch-carbon fiber preform obtained from S2 with resin slurries A, B, and C, with increasing residual carbon content, followed by curing and pyrolysis, until the density of the pitch-carbon fiber preform reaches 1.30-1.50 g / cm³. 3 The steps for preparing a gradient porous C / C composite skeleton;

[0025] The resin slurry A includes thermosetting resin A;

[0026] The resin slurry B includes thermosetting resin B;

[0027] The resin slurry C includes thermosetting resin C;

[0028] The thermosetting resin A includes any one of epoxy resin, furan resin, and pyrrolidone-type phthalonitrile resin;

[0029] The thermosetting resin B includes any one of acetylene-based polyimide resin, bismaleimide resin, and pyrrolidone-type phthalonitrile resin;

[0030] The thermosetting resin C includes any one of polybenzoxazine resin, styrene-based polybenzoxazine resin, and phenolic resin;

[0031] The curing agent includes tetrahydrophthalic anhydride, xylenesulfonic acid, diethylenetriamine, or hexamethylenetetramine;

[0032] The organic solvent includes ethanol, dimethylamide, acetone, or xylene;

[0033] In the resin slurry, the mass ratio of thermosetting resin, curing agent and organic solvent is 60-120:5-10:80-140.

[0034] The vacuum impregnation process involves a vacuum level of -0.1 to 0 MPa and a duration of 1 to 2 hours.

[0035] The curing temperature is 100-150℃, and the time is 4-16 hours;

[0036] The pyrolysis temperature is 800-1200℃, and the time is 1-5h.

[0037] The vacuum degree of the reactive infiltrating silicon is ≤1000Pa;

[0038] The heating rate of the reactive infiltration silicon is 5-10℃ / min;

[0039] The holding temperature for the reactive infiltration of silicon is 1500-1800℃;

[0040] The holding time for the reactive melting and infiltration of silicon is 120-180 min;

[0041] The silicon powder used in the reactive infiltration silicon carbide has a particle size of 30-50 μm and a silicon mass fraction of ≥98% in the silicon powder.

[0042] The C / C-SiC composite material prepared by the method described above.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] This invention utilizes graphene oxide grafted onto the surface of pitch-carbon fiber to form a transition layer, which can protect the carbon fiber from high-temperature corrosion by silicon and significantly improve its wettability with resin.

[0045] The preform structure used in this invention is a three-dimensional orthogonal braided fiber structure with similar fiber volume fractions in all directions. The expansion of silicon carbide and silicon can then be limited by the negative expansion effect of carbon fiber, thereby achieving near-zero expansion of the composite material.

[0046] The composite material prepared by this invention has the advantages of low density, near-zero in-plane and thickness thermal expansion coefficients, and excellent mechanical properties, which can meet the application requirements of optomechanical structural components in low-temperature space environments. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the embodiments. It should be noted that the embodiments described below are intended to facilitate the understanding of the present invention and should not be regarded as specific limitations of the present invention.

[0048] This invention provides a method for preparing C / C-SiC composite materials. Specifically, firstly, graphene oxide is grafted onto the surface of pitch-carbon fibers. The grafted graphene oxide forms a transition layer, which can protect the carbon fibers from high-temperature corrosion by silicon and significantly improve the wettability with resin. Then, the pitch-carbon fibers are woven into a three-dimensional quasi-isotropic pitch-carbon fiber preform; therefore, the fiber volume fraction in all directions of the pitch-carbon fiber preform is close. Next, a thermosetting resin is uniformly mixed with a curing agent and an organic solvent to obtain a resin slurry. The obtained pitch-carbon fiber preform is then vacuum impregnated in the resin slurry, followed by curing and pyrolysis until the density of the pitch-carbon fiber preform reaches 1.30-1.50 g / cm³. 3 A porous C / C composite skeleton is prepared. Finally, the porous C / C composite skeleton is subjected to reactive infiltration with silicon to carbonize the resin and react with silicon to generate SiC. This utilizes the negative expansion effect of carbon fibers to limit the expansion of silicon carbide and silicon, achieving near-zero expansion of the composite material. Specifically, the carbon fibers in the pitch-carbon fiber preform are perpendicular to each other in three directions, forming an orthogonal structure, and the edges of the pitch-carbon fiber preform form an interlocking structure. Furthermore, the volume fraction of pitch-carbon fiber in the X direction of the pitch-carbon fiber preform is 15-20 vol%; the volume fraction of pitch-carbon fiber in the Y direction is 15-20 vol%; and the volume fraction of pitch-carbon fiber in the Z direction is 8-12 vol%. The C / C-SiC composite material prepared by the above method has a planar thermal expansion coefficient of approximately 0.03-0.46 ppm / K and a thickness thermal expansion coefficient of approximately 0.18-0.69 ppm / K in the temperature range of 25-200℃. Both are close to 0. Therefore, its low thermal expansion coefficient can improve the adaptability of components made from C / C-SiC composite material in environments with drastic temperature changes.

[0049] Furthermore, the surface of the pitch-carbon fiber can be modified first using plasma, and then graphene oxide can be grafted onto the surface of the carbon fiber using a silane coupling agent grafting method. Plasma treatment can modify the surface of the pitch-carbon fiber, introducing a large number of polar groups onto the fiber surface, allowing the pitch-carbon fiber to be grafted with graphene oxide more effectively.

[0050] Graphene oxide significantly improves wettability with resin precursor solutions, substantially increases the bonding interface between carbon fibers and the silicon carbide ceramic matrix, and enhances the interfacial bonding force between the carbon fiber reinforcement and the ceramic matrix, ensuring effective load transfer between the ceramic matrix and the fiber reinforcement. Furthermore, the silane coupling agent grafting method can create a "molecular bridge" between the interface of graphene oxide and pitch-coated carbon fibers, allowing graphene oxide to graft onto the carbon fiber surface to form a tight interfacial bond, increasing interfacial adhesion strength. This prevents silicon-containing liquids from penetrating into the carbon fiber / graphene oxide interface during subsequent precursor impregnation, pyrolysis, and reactive infiltration processes, effectively protecting the carbon fibers from high-temperature silicon corrosion.

[0051] Specifically, the plasma treatment method uses one or more of Ar, N2, and O2 as the plasma source; the plasma treatment method uses a discharge power of 200W-800W; and the plasma treatment method uses a treatment time of 10s-100s. Specifically, an alcohol dispersion of graphene oxide and an alcohol solution of a silane coupling agent are mixed to obtain a coupling agent-modified graphene oxide dispersion. Then, the plasma-treated pitch carbon fibers are impregnated in the coupling agent-modified graphene oxide dispersion, removed, and dried to obtain carbon fibers with a graphene oxide-modified surface.

[0052] Specifically, in the alcohol dispersion of graphene oxide, the ratio of alcohol solvent to graphene oxide is 10 mL: 30-60 mg; specifically, in the alcohol solution of silane coupling agent, the mass fraction of silane coupling agent is 2-5%.

[0053] Specifically, in the coupling agent modified graphene oxide dispersion, the alcohol dispersion of graphene oxide and the alcohol solution of silane coupling agent are in a volume ratio of 10:1-5.

[0054] Specifically, the silane coupling agent is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β(aminoethyl)-γ-aminopropyltriethoxysilane.

[0055] Further, the asphalt carbon fiber preform is vacuum impregnated sequentially with resin slurry A, resin slurry B and resin slurry C with increasing residual carbon content, and then cured and pyrolyzed until the density of the asphalt carbon fiber preform reaches 1.30-1.50 g / cm3, thus obtaining a gradient porous C / C composite skeleton.

[0056] The resin slurry A includes thermosetting resin A;

[0057] The resin slurry B includes thermosetting resin B;

[0058] The resin slurry C includes thermosetting resin C;

[0059] The thermosetting resin A includes any one of epoxy resin, furan resin, and pyrrolidone-type phthalonitrile resin;

[0060] The thermosetting resin B includes any one of acetylene-based polyimide resin, bismaleimide resin, and pyrrolidone-type phthalonitrile resin;

[0061] The thermosetting resin C includes any one of polybenzoxazine resin, styrene-based polybenzoxazine resin, and phenolic resin. The structure of the carbon skeleton impregnated and pyrolyzed by the thermosetting resin is controlled to be a gradient porous structure, reducing the free silicon content in the composite material after reaction and infiltration. The resulting composite material has advantages such as low density, near-zero in-plane and thickness thermal expansion coefficients, and excellent mechanical properties, meeting the application requirements of optomechanical structural components in low-temperature space environments. This invention uses a multi-level residual carbon rate thermosetting resin for curing and pyrolysis. During the process, the escape of a large amount of gas produces a significant pore-forming effect, resulting in a gradient porous carbon-based structure. The carbon matrix impregnated and pyrolyzed by the multi-level residual carbon rate thermosetting resin precursor of this invention has a gradient porous structure, filling the pores of varying sizes in the composite material. This forms a gradient porous structure in the C / C composite skeleton, providing more numerous, smaller, and more uniformly distributed reaction spaces for molten silicon during subsequent reaction and infiltration, increasing the specific surface area of ​​the reaction, and effectively reducing the free silicon content in the composite material. The mass percentage of free silicon in the composite material is reduced by 40-80%, and the strength is increased by 20-45%. Therefore, controlling the structure of the thermosetting resin impregnated pyrolytic carbon skeleton to be a gradient porous structure can reduce the content of free silicon in the composite material after reactive melting and infiltration. As a result, the obtained composite material has the advantages of low density, near-zero in-plane and thickness thermal expansion coefficients, and excellent mechanical properties, which can meet the application requirements of optomechanical structural components in low-temperature space environments.

[0062] Specifically, the curing agent includes tetrahydrophthalic anhydride, xylenesulfonic acid, diethylenetriamine, or hexamethylenetetramine; the organic solvent includes ethanol, dimethylamide, acetone, or xylene; and the mass ratio of thermosetting resin, curing agent, and organic solvent in the resin slurry is 60-120:5-10:80-140.

[0063] Specifically, the vacuum impregnation process involves a vacuum degree of -0.1 to 0 MPa and a time of 1 to 2 hours; the curing temperature is 100 to 150°C and the time is 4 to 16 hours; the pyrolysis temperature is 800 to 1200°C and the time is 1 to 5 hours.

[0064] Specifically, the vacuum degree of the reactive infiltrating silicon is ≤1000Pa; the heating rate of the reactive infiltrating silicon is 5 to 10℃ / min; the holding temperature of the reactive infiltrating silicon is 1500 to 1800℃; the holding time of the reactive infiltrating silicon is 120 to 180min; the particle size of the silicon powder used for reactive infiltrating silicon carbide is 30 to 50μm, and the mass fraction of silicon in the silicon powder is ≥98%.

[0065] Example 1

[0066] A method for preparing a near-zero expansion C / C-SiC composite material includes the following steps:

[0067] (1) Surface modification of pitch carbon fiber

[0068] A. The pitch-carbon fiber was placed on a plasma device in an open environment, and plasma was sprayed onto the surface of the carbon fiber, causing the carbon fiber to move in the plasma atmosphere. The treatment power was 100W, and the treatment time was 60s, resulting in surface modification. The treated carbon fiber was then vacuum dried at 60℃ to constant weight to obtain plasma-treated carbon fiber.

[0069] B. Disperse 50 mg of graphene oxide in 10 mL of ethanol, add 2 mL of 5% silane coupling agent γ-aminopropyltriethoxysilane ethanol solution to obtain silane coupling agent modified graphene oxide ethanol solution; impregnate the plasma-treated carbon fibers in the silane coupling agent modified graphene oxide ethanol solution, take them out after 1 h, and dry them at 60 °C to obtain graphene oxide-modified pitch carbon fibers.

[0070] (2) Preform preparation

[0071] The modified pitch carbon fiber was three-dimensionally woven to obtain a three-dimensional quasi-isotropic pitch carbon fiber preform with a pitch carbon fiber volume fraction of 10 vol% in the Z direction and 15 vol% in the X and Y directions. The yarns in the three directions inside the woven structure are perpendicular to each other, forming an orthogonal structure, and an interlocking structure is formed at the edge of the preform.

[0072] (3) Preparation of C / C composite materials

[0073] A. First, epoxy resin, diethylenetriamine, and xylene are weighed and mixed evenly in a mass ratio of 120:10:80 to obtain resin slurry A. The pitch carbon fiber preform is pressure impregnated with slurry A and cured at 120℃ for 4 hours. The impregnation pressure is 2MPa and the time is 2 hours. Then, the temperature is raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain a porous C / C composite skeleton.

[0074] B. Then, bismaleimide resin, tetrahydrophthalic anhydride and dimethylformamide were weighed and mixed evenly in a mass ratio of 80:10:120 to obtain resin slurry B. The porous C / C composite skeleton was pressure impregnated with slurry B and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain the porous C / C composite skeleton.

[0075] C. Finally, phenolic resin, hexamethylenetetramine (urotropine), and ethanol were weighed and mixed evenly in a mass ratio of 60:10:140 to obtain resin slurry C. The porous C / C composite skeleton was pressure impregnated with slurry C and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain a porous C / C composite skeleton. The process was repeated until the density of the porous C / C composite skeleton reached 1.30 g / cm3, thus obtaining the C / C composite material.

[0076] (4) Ceramicization and densification

[0077] Under high temperature and vacuum conditions of 1650℃, Si powder (purity ≥98%, particle size 50μm) was infiltrated into the C / C composite material obtained in step (3) for a reaction time of 120min to obtain C / C-SiC composite material with a density of 2.21g / cm3, a thermal expansion coefficient in the planar direction of about 0.37ppm / K (25-200℃), and a thermal expansion coefficient in the thickness direction of about 0.69ppm / K (25-200℃).

[0078] Example 2

[0079] A method for preparing a near-zero expansion C / C-SiC composite material includes the following steps:

[0080] (1) Surface modification of pitch carbon fiber

[0081] A. The pitch-carbon fiber was placed on a plasma device in an open environment, and plasma was sprayed onto the surface of the carbon fiber, causing the carbon fiber to move in the plasma atmosphere. The treatment power was 100W, and the treatment time was 60s, resulting in surface modification. The treated carbon fiber was then vacuum dried at 60℃ to constant weight to obtain plasma-treated carbon fiber.

[0082] B. Disperse 60 mg of graphene oxide in 10 mL of ethanol, add 2 mL of 5% silane coupling agent γ-aminopropyltriethoxysilane ethanol solution to obtain silane coupling agent modified graphene oxide ethanol solution; impregnate the plasma-treated carbon fibers in the silane coupling agent modified graphene oxide ethanol solution, take them out after 1 h, and dry them at 60 °C to obtain pitch carbon fibers with graphene oxide surface modification.

[0083] (2) Preform preparation

[0084] The modified pitch carbon fiber was three-dimensionally woven to obtain a three-dimensional quasi-isotropic pitch carbon fiber preform with a pitch carbon fiber volume fraction of 10 vol% in the Z direction and 15 vol% in the X and Y directions. The yarns in the three directions inside the woven structure are perpendicular to each other, forming an orthogonal structure, and an interlocking structure is formed at the edge of the preform.

[0085] (3) Preparation of C / C composite materials

[0086] A. First, furan resin, dimethylbenzenesulfonic acid and xylene are weighed and mixed evenly in a mass ratio of 120:10:80 to prepare slurry A. The pitch carbon fiber preform is pressure impregnated with slurry A and cured at 120℃ for 4 hours. The impregnation pressure is 2MPa and the time is 2 hours. Then, the temperature is raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for pyrolysis for 3 hours to obtain a porous C / C composite skeleton.

[0087] B. Then, bismaleimide resin, tetrahydrophthalic anhydride and dimethylformamide were weighed and mixed evenly in a mass ratio of 80:10:120 to prepare slurry B. The porous C / C composite skeleton was pressure impregnated with slurry B and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain the porous C / C composite skeleton.

[0088] C. Finally, phenolic resin, hexamethylenetetramine (urotropine), and ethanol were weighed and mixed evenly in a mass ratio of 60:10:140 to prepare slurry C. The porous C / C composite skeleton was pressure impregnated with slurry C and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain a porous C / C composite skeleton. The process was repeated until the density of the porous C / C composite skeleton reached 1.40 g / cm3, thus obtaining the C / C composite material.

[0089] (4) Ceramicization and densification

[0090] Under high temperature and vacuum conditions of 1700℃, Si powder (purity ≥98%, particle size 50μm) was infiltrated into the C / C composite material obtained in step (3) for a reaction time of 150min to obtain C / C-SiC composite material with a density of 2.31g / cm3, a thermal expansion coefficient in the planar direction of about 0.46ppm / K (25-200℃), and a thermal expansion coefficient in the thickness direction of about 0.59ppm / K (25-200℃).

[0091] Example 3

[0092] A method for preparing a near-zero expansion C / C-SiC composite material includes the following steps:

[0093] (1) Surface modification of pitch carbon fiber

[0094] A. The pitch-carbon fiber was placed on a plasma device in an open environment, and plasma was sprayed onto the surface of the carbon fiber, causing the carbon fiber to move in the plasma atmosphere. The treatment power was 100W, and the treatment time was 60s, resulting in surface modification. The treated carbon fiber was then vacuum dried at 60℃ to constant weight to obtain plasma-treated carbon fiber.

[0095] B. Disperse 60 mg of graphene oxide in 10 mL of ethanol, add 2 mL of 5% silane coupling agent γ-aminopropyltriethoxysilane ethanol solution to obtain silane coupling agent modified graphene oxide ethanol solution; impregnate the plasma-treated carbon fibers in the silane coupling agent modified graphene oxide ethanol solution, take them out after 1 h, and dry them at 60 °C to obtain pitch carbon fibers with graphene oxide surface modification.

[0096] (2) Preform preparation

[0097] The modified pitch carbon fiber was three-dimensionally woven to obtain a three-dimensional quasi-isotropic pitch carbon fiber preform with a pitch carbon fiber volume fraction of 10 vol% in the Z direction and 15 vol% in the X and Y directions. The yarns in the three directions inside the woven structure are perpendicular to each other, forming an orthogonal structure, and an interlocking structure is formed at the edge of the preform.

[0098] (3) Preparation of C / C composite materials

[0099] A. First, furan resin, dimethylbenzenesulfonic acid and xylene are weighed and mixed evenly in a mass ratio of 120:10:80 to prepare slurry A. The pitch carbon fiber preform is pressure impregnated with slurry A and cured at 120℃ for 4 hours. The impregnation pressure is 2MPa and the time is 2 hours. Then, the temperature is raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for pyrolysis for 3 hours to obtain a porous C / C composite skeleton.

[0100] B. Then, pyrrolidone-type phthalonitrile resin, tetrahydrophthalic anhydride and dimethylformamide were weighed and mixed evenly in a mass ratio of 80:10:120 to prepare slurry B. The porous C / C composite skeleton was pressure impregnated with slurry B and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to carry out pyrolysis, thus obtaining the porous C / C composite skeleton.

[0101] C. Finally, phenolic resin, hexamethylenetetramine (urotropine), and ethanol were weighed and mixed evenly in a mass ratio of 60:10:140 to prepare slurry C. The porous C / C composite skeleton was pressure impregnated with slurry C and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain a porous C / C composite skeleton. The process was repeated until the density of the porous C / C composite skeleton reached 1.50 g / cm3, thus obtaining the C / C composite material.

[0102] (4) Ceramicization and densification

[0103] Under high temperature and vacuum conditions of 1800℃, Si powder (purity ≥98%, particle size 50μm) was infiltrated into the C / C composite material obtained in step (3) for a reaction time of 180min to obtain C / C-SiC composite material with a density of 2.26g / cm3, a thermal expansion coefficient in the planar direction of about 0.23ppm / K (25-200℃), and a thermal expansion coefficient in the thickness direction of about 0.18ppm / K (25-200℃).

[0104] Comparative Example 1

[0105] A method for preparing a near-zero expansion C / C-SiC composite material includes the following steps:

[0106] (1) Surface modification of pitch carbon fiber

[0107] A. The pitch-carbon fiber was placed on a plasma device in an open environment, and plasma was sprayed onto the surface of the carbon fiber, causing the carbon fiber to move in the plasma atmosphere. The treatment power was 100W, and the treatment time was 60s, resulting in surface modification. The treated carbon fiber was then vacuum dried at 60℃ to constant weight to obtain plasma-treated carbon fiber.

[0108] B. Disperse 60 mg of graphene oxide in 10 mL of ethanol, add 2 mL of 5% silane coupling agent γ-aminopropyltriethoxysilane ethanol solution to obtain silane coupling agent modified graphene oxide ethanol solution; impregnate the plasma-treated carbon fibers in the silane coupling agent modified graphene oxide ethanol solution, take them out after 1 h, and dry them at 60 °C to obtain pitch carbon fibers with graphene oxide surface modification.

[0109] (2) Preform preparation

[0110] The modified pitch carbon fiber was three-dimensionally woven to obtain a three-dimensional quasi-isotropic pitch carbon fiber preform with a pitch carbon fiber volume fraction of 10 vol% in the Z direction and 15 vol% in the X and Y directions. The yarns in the three directions inside the woven structure are perpendicular to each other, forming an orthogonal structure, and an interlocking structure is formed at the edge of the preform.

[0111] (3) Preparation of C / C composite materials

[0112] First, furan resin, dimethylbenzenesulfonic acid, and xylene were weighed and mixed evenly in a mass ratio of 120:10:80 to prepare slurry A. The pitch carbon fiber preform was pressure impregnated with slurry A and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for pyrolysis for 3 hours until the density of the porous C / C composite skeleton reached 1.50 g / cm3, thus obtaining the C / C composite material.

[0113] (4) Ceramicization and densification

[0114] Under high temperature and vacuum conditions of 1800℃, Si powder (purity ≥98%, particle size 50μm) was infiltrated into the C / C composite material obtained in step (3) for a reaction time of 180min to obtain C / C-SiC composite material with a density of 1.95g / cm3, a thermal expansion coefficient in the planar direction of about -0.64ppm / K (25-200℃), and a thermal expansion coefficient in the thickness direction of about 1.44ppm / K (25-200℃).

[0115] Comparative Example 2

[0116] A method for preparing a near-zero expansion C / C-SiC composite material includes the following steps:

[0117] (1) Surface modification of pitch carbon fiber

[0118] A. The pitch-carbon fiber was placed on a plasma device in an open environment, and plasma was sprayed onto the surface of the carbon fiber, causing the carbon fiber to move in the plasma atmosphere. The treatment power was 100W, and the treatment time was 60s, resulting in surface modification. The treated carbon fiber was then vacuum dried at 60℃ to constant weight to obtain plasma-treated carbon fiber.

[0119] B. Disperse 60 mg of graphene oxide in 10 mL of ethanol, add 2 mL of 5% silane coupling agent γ-aminopropyltriethoxysilane ethanol solution to obtain silane coupling agent modified graphene oxide ethanol solution; impregnate the plasma-treated carbon fibers in the silane coupling agent modified graphene oxide ethanol solution, take them out after 1 h, and dry them at 60 °C to obtain pitch carbon fibers with graphene oxide surface modification.

[0120] (2) Preform preparation

[0121] The modified pitch carbon fiber was woven in two dimensions to obtain a two-dimensional pitch carbon fiber preform with a pitch carbon fiber volume fraction of 20 vol% in the X and Y directions. The yarns in the two directions inside the woven structure are perpendicular to each other.

[0122] (3) Preparation of C / C composite materials

[0123] A. First, furan resin, dimethylbenzenesulfonic acid and xylene are weighed and mixed evenly in a mass ratio of 120:10:80 to prepare slurry A. The pitch carbon fiber preform is pressure impregnated with slurry A and cured at 120℃ for 4 hours. The impregnation pressure is 2MPa and the time is 2 hours. Then, the temperature is raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for pyrolysis for 3 hours to obtain a porous C / C composite skeleton.

[0124] B. Then, pyrrolidone-type phthalonitrile resin, tetrahydrophthalic anhydride and dimethylformamide were weighed and mixed evenly in a mass ratio of 80:10:120 to prepare slurry B. The porous C / C composite skeleton was pressure impregnated with slurry B and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to carry out pyrolysis, thus obtaining the porous C / C composite skeleton.

[0125] C. Finally, phenolic resin, hexamethylenetetramine (urotropine), and ethanol were weighed and mixed evenly in a mass ratio of 60:10:140 to prepare slurry C. The porous C / C composite skeleton was pressure impregnated with slurry C and cured at 120℃ for 4 hours. The impregnation pressure was 2MPa and the time was 2 hours. Then, the temperature was raised to 800℃ at a heating rate of 5℃ / min under a nitrogen atmosphere for 3 hours to obtain a porous C / C composite skeleton. The process was repeated until the density of the porous C / C composite skeleton reached 1.50 g / cm3, thus obtaining the C / C composite material.

[0126] (4) Ceramicization and densification

[0127] Under high temperature and vacuum conditions of 1800℃, Si powder (purity ≥98%, particle size 50μm) was infiltrated into the C / C composite material obtained in step (3) for a reaction time of 180min to obtain C / C-SiC composite material with a density of 2.35g / cm3, a thermal expansion coefficient in the planar direction of about 1.13ppm / K (25-200℃), and a thermal expansion coefficient in the thickness direction of about 2.18ppm / K (25-200℃).

[0128] The performance results of the composite materials are shown in Table 1.

[0129]

[0130]

Claims

1. A method for preparing a C / C-SiC composite material, characterized in that: The steps include: S1 Grafting graphene oxide onto the surface of pitch-carbon fiber; S2 braids the pitch-carbon fiber obtained in S1 into a three-dimensional quasi-isotropic pitch-carbon fiber preform; In step S3, thermosetting resins A, B, and C are mixed uniformly with a curing agent and an organic solvent to prepare resin slurries A, B, and C, respectively. Then, the pitch-carbon fiber preform obtained in step S2 is sequentially vacuum impregnated with resin slurries A, B, and C, with the residual carbon content increasing from lowest to highest. The mixture is then cured and pyrolyzed until the density of the pitch-carbon fiber preform reaches 1.30-1.50 g / cm³. 3 The steps for preparing a gradient porous C / C composite skeleton; The resin slurry A includes thermosetting resin A; The resin slurry B includes thermosetting resin B; The resin slurry C includes thermosetting resin C; The thermosetting resin A includes any one of epoxy resin, furan resin, and pyrrolidone-type phthalonitrile resin; The thermosetting resin B includes any one of acetylene-based polyimide resin and bismaleimide resin; The thermosetting resin C includes any one of polybenzoxazine resin, styrene-based polybenzoxazine resin, and phenolic resin; The curing agent includes tetrahydrophthalic anhydride, xylenesulfonic acid, diethylenetriamine, or hexamethylenetetramine; The organic solvent includes ethanol, dimethylamide, acetone, or xylene; In the resin slurry, the mass ratio of thermosetting resin, curing agent and organic solvent is 60-120:5-10:80-140; S4 involves reactively infiltrating silicon into the gradient porous C / C composite material skeleton obtained in S3 to obtain the C / C-SiC composite material. The carbon fibers in the asphalt carbon fiber preform are perpendicular to each other in three directions, forming an orthogonal structure, and the edges of the asphalt carbon fiber preform form an interlocking structure. In the X direction, the volume fraction of the asphalt carbon fiber preform is 15-20 vol%. In the Y direction, the volume fraction of the asphalt carbon fiber preform is 15-20 vol%. The volume fraction of the pitch-carbon fiber preform in the Z direction is 8-12 vol%. The C / C-SiC composite material has a planar coefficient of thermal expansion of 0.03-0.46 ppm / K and a thickness coefficient of thermal expansion of 0.18-0.69 ppm / K.

2. The method for preparing the C / C-SiC composite material as described in claim 1, characterized in that: S1 involves using plasma to modify the surface of the pitch-carbon fiber, and then using a silane coupling agent grafting method to graft graphene oxide onto the surface of the carbon fiber.

3. The method for preparing the C / C-SiC composite material as described in claim 2, characterized in that: The plasma treatment method uses one or more of Ar, N2, and O2 plasmas; the discharge power used in the plasma treatment method is 200W-800W; and the treatment time used in the plasma treatment method is 10s-100s.

4. The method for preparing the C / C-SiC composite material as described in claim 2, characterized in that: S1 includes the steps of mixing an alcohol dispersion of graphene oxide and an alcohol solution of a silane coupling agent to obtain a coupling agent-modified graphene oxide dispersion, then impregnating the plasma-treated pitch carbon fiber in the coupling agent-modified graphene oxide dispersion, and finally removing and drying it.

5. The method for preparing the C / C-SiC composite material as described in claim 4, characterized in that: In the alcohol dispersion of graphene oxide, the ratio of alcohol solvent to graphene oxide is 10 mL: 30-60 mg. In the alcohol solution of the silane coupling agent, the mass fraction of the silane coupling agent is 2-5%; In the modified graphene oxide dispersion of the coupling agent, the alcohol dispersion of graphene oxide and the alcohol solution of silane coupling agent are in a volume ratio of 10:1-5.

6. The method for preparing the C / C-SiC composite material as described in claim 4, characterized in that: The silane coupling agent is at least one of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, and N-β(aminoethyl)-γ-aminopropyltriethoxysilane.

7. The method for preparing the C / C-SiC composite material as described in claim 1, characterized in that: The vacuum impregnation process involves a vacuum level of -0.1 to 0 MPa and a duration of 1 to 2 hours. The curing temperature is 100-150℃, and the time is 4-16 hours; The pyrolysis temperature is 800-1200℃, and the time is 1-5h.

8. The method for preparing the C / C-SiC composite material as described in claim 1, characterized in that: The vacuum degree of the reactive infiltrating silicon is ≤1000Pa; The heating rate of the reactive infiltration silicon is 5-10℃ / min; The holding temperature for the reactive infiltration of silicon is 1500-1800℃; The holding time for the reactive melting and infiltration of silicon is 120-180 min; The silicon powder used in the reactive infiltration silicon has a particle size of 30-50 μm and a silicon mass fraction of ≥98%.

9. The C / C-SiC composite material prepared by the method for preparing C / C-SiC composite material according to any one of claims 1-8.

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