Graphene modified carbon nanotube fiber reinforced ceramic matrix composite material and preparation method thereof

Abstract

The invention relates to a graphene modified carbon nanotube fiber reinforced ceramic matrix composite material and a preparation method thereof. The method comprises the following steps: enabling a carbon nanotube fiber tow to pass through a graphene dispersion liquid, and rolling, washing and drying the carbon nanotube fiber tow; preparing the obtained graphene modified carbon nanotube fiber bundle into a carbon nanotube fiber preform, depositing a carbon interface layer, treating at 1800-3200 DEG C to obtain a modified carbon nanotube fiber preform, performing RTM (Resin Transfer Molding) on the modified carbon nanotube fiber preform and phenolic resin, and performing infiltration siliconizing reaction or directly performing PIP (Polyisoprene-Polyisoprene-Polyisoprene) on the modified carbon nanotube fiber preform and a ceramic precursor to obtain the graphene modified carbon nanotube composite material. The graphene modified carbon nanotube fiber reinforced ceramic matrix composite material is prepared. The preparation method solves the problems that carbon nanotube fibers are poor in bundling property, a woven preform is easy to wear and break, the thermal resistance between the fibers and a ceramic matrix is relatively large, the fibers are damaged in a matrix infiltration process, and the material performance is reduced, and the ceramic-based composite material with efficient heat conduction and high mechanical properties is prepared.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic matrix composite material preparation, and particularly relates to a graphene modified carbon nanotube fiber reinforced ceramic matrix composite material and a preparation method thereof. BACKGROUND

[0002] Under high-speed flight state, the thermal structure components of the aircraft will face the test of extreme service conditions, and extremely strict requirements are put forward for the thermal physical properties of the related materials. The material with high thermal conductivity can quickly transfer the local high heat load to the low temperature area, quickly reduce the thermal damage of the local structure, and prolong the service life of the material. The ceramic matrix composite material, taking fiber as the reinforcing body and ceramic material as the matrix, is an important part of the super-high temperature structure composite material, and has the advantages of high efficient heat transfer and high temperature heat resistance. In addition to the excellent performance of the ceramic material, the ceramic matrix composite material also has the advantages of light weight and high strength of the reinforcing fiber. The carbon nanotube fiber has high thermal conductivity and mechanical properties, but the fiber has poor bundling property and is easy to break during the weaving of the preform. The bundle structure is not tight, the heat transfer path is discontinuous, the thermal resistance between the fiber and the ceramic matrix is large, and the heat dissipation performance of the composite material is affected. At the same time, the fiber is damaged during the matrix infiltration process, and the performance of the composite material is reduced. Directly using chemical vapor deposition pyrolytic carbon has problems such as uneven deposition thickness and large thermal resistance between the interface layer and the ceramic matrix.

[0003] In summary, it is necessary to provide a graphene modified carbon nanotube fiber as a high thermal conductivity ceramic matrix composite material and a preparation method thereof. SUMMARY

[0004] In order to solve one or more technical problems in the prior art, the application provides a graphene modified carbon nanotube fiber reinforced ceramic matrix composite material and a preparation method thereof.

[0005] In a first aspect, the application provides a preparation method of a graphene modified carbon nanotube fiber reinforced ceramic matrix composite material, and the method comprises the following steps: (1) passing a carbon nanotube fiber bundle at a speed of 1-4 m / min through a graphene dispersion liquid, and performing rolling, water washing and drying treatment to form a graphene layer on the surface of the fiber, to obtain a graphene modified carbon nanotube fiber bundle; (2) preparing the graphene modified carbon nanotube fiber bundle into a carbon nanotube fiber preform, then preparing a carbon interface layer on the surface of the carbon nanotube fiber preform through chemical vapor deposition, and then performing high temperature treatment at 1800-3200 ℃ to obtain a modified carbon nanotube fiber preform; (3) The modified carbon nanotube fiber preform and phenolic resin are subjected to RTM process to obtain CNTF / C preform, and then the CNTF / C preform is reacted and infiltrated with a melt infiltrator to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material; or the ceramic precursor is reacted with the modified carbon nanotube fiber preform by impregnation pyrolysis method to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material.

[0006] Preferably, in step (1): the graphene dispersion is prepared by dispersing graphene in an aqueous solution containing a surfactant to obtain a graphene dispersion; preferably, the surfactant is polyvinylpyrrolidone and / or sodium dodecyl sulfate; preferably, the concentration of graphene in the graphene dispersion is 4~10 mg / g; preferably, the mass ratio of surfactant to graphene in the aqueous solution containing surfactant is (1~2):1; preferably, the graphene is dispersed in the aqueous solution containing surfactant by ultrasonic treatment.

[0007] Preferably, in step (1), the drying temperature is 60~100℃.

[0008] Preferably, in step (2): the method of preparing graphene-modified carbon nanotube fiber bundles into carbon nanotube fiber preforms is selected from one or more of needle punching, orthogonal triaxial weaving, stitching, fine weaving and puncture weaving, and 2.5D weaving; preferably, the 2.5D weaving is 2.5D contour weaving.

[0009] Preferably, when orthogonal triaxial weaving and / or 2.5D weaving is used, the carbon nanotube fiber preform is entirely woven from graphene-modified carbon nanotube fiber bundles, or is woven from a mixture of graphene-modified carbon nanotube fiber bundles and carbon fiber bundles.

[0010] Preferably, in step (2): the temperature of the chemical vapor deposition is 900~1100℃, the time is 50~150h, and the pressure is 10~150Pa; and / or the high-temperature treatment is carried out in an inert atmosphere, the time of the high-temperature treatment is 0.5~1h, and the heating rate is 200~500℃ / h.

[0011] Preferably, the preparation of the CNTF / C embryo in step (3) includes the following sub-steps: (a) The modified carbon nanotube fiber preform is placed in the mold cavity; (b) Phenolic resin is injected into the mold cavity and the modified carbon nanotube fiber preform is impregnated with phenolic resin, followed by curing and pyrolysis. (c) Repeat step (b) at least once to obtain CNTF / C embryos.

[0012] Preferably, the injection pressure of the phenolic resin is 2-3 MPa, and the injection rate is 40-60 mL / min; the time for impregnating the modified carbon nanotube fiber preform with phenolic resin is 1-3 h, preferably 2 h; the curing temperature is 220-260℃, and the time is 3-6 h; the pyrolysis is carried out under an inert atmosphere, the pyrolysis temperature is 1600-1700℃, and the pyrolysis time is 2-5 h; and / or step (b) is repeated 2-4 times.

[0013] Preferably, in step (3): silicon and / or zirconium-silicon alloy is used as the infiltration agent; and / or the reaction infiltration temperature is 1600~1700℃ and the time is 2~4h.

[0014] Preferably, in step (3): the ceramic precursor is one or more of zirconium silicon precursor, silicon carbide precursor, zirconium carbide precursor, and hafnium carbide precursor.

[0015] In a second aspect, the present invention provides a graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material prepared by the preparation method described in the first aspect of the present invention.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention utilizes graphene to modify the interface of carbon nanotube fibers. By coating the fiber surface with graphene, the problem of low mechanical properties and poor bundle structure caused by weak bonding between radial carbon nanotube fibers is solved. Compared with the method of directly immersing carbon nanotube fibers in graphene dispersion, this invention adopts a continuous coating combined with rolling and drying process, so that the carbon nanotube fiber bundle passes through the graphene dispersion continuously at an appropriate speed and is subjected to rolling and drying treatment. This can form a uniform, dense and well-oriented graphene coating layer on the surface of carbon nanotube fibers. This coating layer can build a stable interface transition structure on the fiber surface, enhance the mutual bonding force and friction coordination between radial carbon nanotube fibers, and significantly improve the problems of uneven slippage, fuzzing and fiber breakage of carbon nanotube fibers during the bundling process, thereby improving the overall density and forming stability of the fiber bundle.

[0017] (2) The present invention improves the weaving toughness and wear resistance of fiber bundles while improving the interface performance, and solves the problems of fuzzing and fiber breakage in the current carbon nanotube fiber weaving process.

[0018] (3) The graphene layer formed on the surface of carbon nanotube fibers in this invention can induce the deposition and orientation of carbon interface layer during the chemical vapor deposition of carbon layer and high temperature treatment, forming a highly oriented carbon interface layer, improving the matching between carbon nanotube fiber interface and ceramic matrix, thereby reducing interface thermal resistance and improving the thermal conductivity of material. The uniform, dense, and well-oriented graphene layer formed in this invention can serve as a preferred site for carbon source adsorption and nucleation during chemical vapor deposition, inducing the deposited carbon layer to grow along the orientation direction of the graphene sheets, forming a continuous and tightly bonded carbon interface layer. In the subsequent high-temperature treatment at 1800–3200 °C, the graphene layer further induces the deposited carbon atoms to rearrange their orientation along their lattice direction, forming a highly oriented carbon interface layer. This not only improves the graphitization degree, lattice matching, and bonding strength between the carbon layer and carbon nanotube fibers, but also forms a stable stress transmission channel within the fiber bundle, further enhancing the overall synergistic deformation capacity and toughness of the fiber bundle. Through the interfacial structure evolution induced by the graphene layer, the entire process of carbon nanotube fiber modification from monofilament interface modification to bundle structure densification, and then to carbon interface layer orientation strengthening is achieved, thereby significantly improving the interfacial stability and mechanical-thermal integrated properties of ceramic matrix composites. This is of great significance for the preparation of ceramic matrix composites with efficient thermal conductivity and mechanical properties.

[0019] (4) In this invention, the modified carbon nanotube fiber preform is first formed using resin transfer molding (RTM) to obtain a CNTF / C preform, and then subjected to reactive infiltration silicon treatment. This invention found that by injecting and curing phenolic resin through RTM, followed by high-temperature pyrolysis to form a uniform and continuous carbon-based skeleton, not only is the density and overall structural stability of the preform effectively improved, but a continuous carbon phase transition layer is also formed between the carbon nanotube fibers. This significantly improves the wettability and interface compatibility between the fibers and the subsequent SiC phase. In the subsequent reactive infiltration silicon process, liquid silicon can uniformly penetrate along the carbon skeleton and fully react with the carbon phase to generate a fine and uniformly distributed silicon carbide matrix phase, avoiding the problems of local over-reaction or uneven penetration, and ensuring the uniformity of the structure and the continuity of thermal conductivity of the ceramic matrix composite material. This multi-level interface structure effectively reduces the interfacial thermal resistance and improves the continuity of the heat conduction path, thereby significantly improving the overall thermal conductivity and tensile strength of the material.

[0020] (5) In the process of preparing ceramic matrix by melt infiltration, the graphene layer and induced carbon interface layer formed on the surface of carbon nanotube fibers by the method of the present invention can also effectively avoid damage to the fibers during the melt infiltration reaction, thereby improving the mechanical properties of composite materials. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] The present invention provides a method for preparing graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material in a first aspect, the method comprising the following steps: (1) Carbon nanotube fiber bundles are passed through a graphene dispersion (interface modifier) ​​at a speed of 1-4 m / min (e.g., 1, 1.5, 2, 2.5, 3, 3.5, or 4 m / min), and then subjected to rolling, washing, and drying treatments to form a graphene layer on the fiber surface, thereby obtaining graphene-modified carbon nanotube fiber bundles; in this invention, for example, the carbon nanotube fiber bundles are continuously passed through the graphene dispersion by a traction roller; in this invention, the carbon nanotube fiber bundles can also be referred to as carbon nanotube fiber bundles, which are continuous filament structures composed of multiple carbon nanotube fiber monofilaments; specifically, in this invention, after the carbon nanotube fiber bundles are continuously passed through the above-mentioned graphene dispersion at a speed of 1-4 m / min, they are subjected to rolling treatment, and then... The surfactant is removed by washing, and the fibers are dried and wound up at 60-100℃ using a drying roller to obtain graphene-modified carbon nanotube fiber bundles. In this invention, graphene dispersion is used as an interface modifier, continuously coated on the surface of carbon nanotube fibers. After rolling and drying, a dense graphene layer is formed on the fiber surface. The graphene sheets encapsulate the surface of the carbon nanotube fibers, modifying the carbon nanotube fiber interface and improving the fiber mechanical properties, thereby enhancing the fiber bundling performance. This invention does not impose specific limitations on the carbon nanotube fiber bundles; those skilled in the art can choose conventionally, for example, the tensile strength of the fibers in the carbon nanotube fiber bundles is 3-5 GPa, the room temperature thermal conductivity is 300-600 W / (m·K), and the elongation at break is 4-6%. (2) Graphene-modified carbon nanotube fiber bundles are prepared into carbon nanotube fiber preforms (e.g., two-dimensional or three-dimensional preforms). Then, a carbon interface layer is prepared on the surface of the carbon nanotube fiber preform by chemical vapor deposition. After high temperature treatment at 1800~3200℃, the modified carbon nanotube fiber preform is obtained. At the same time, during the high temperature treatment, the graphene layer induces the deposited carbon to rearrange and reorient along the lattice direction to form a highly graphitized carbon interface layer, which improves the interface matching and thermal conductivity continuity between the fiber and the composite matrix. (3) The modified carbon nanotube fiber preform is subjected to RTM (resin transfer molding) process with phenolic resin to obtain CNTF / C preform, and then the CNTF / C preform is reacted and infiltrated with a melt infiltrator to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material; or step (3) is: the ceramic precursor is reacted with the modified carbon nanotube fiber preform by impregnation pyrolysis (PIP) to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material; the modified carbon nanotube fiber preform obtained by the present invention can also be directly used to obtain ceramic matrix composite material with high thermal conductivity and high mechanical properties by PIP process; in the RTM process, the present invention does not have special requirements for the type of phenolic resin, and those skilled in the art can choose conventionally, such as liquid phenolic resin; the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material obtained by the present invention uses carbon nanotube fibers as thermal conductivity channels and toughening phase; the present invention can, for example, obtain a density of 2.0~4.0 g / cm³. 3 Graphene-modified carbon nanotube fiber reinforced ceramic matrix composites (also referred to as carbon nanotube fiber / thermally conductive ceramic matrix composites).

[0023] This invention utilizes graphene-modified carbon nanotube fiber interfaces. By encapsulating the fiber surface with a 2D graphene structure, it solves the problems of low mechanical properties and poor bundle structure caused by weak inter-fiber bonding in radial carbon nanotubes. Compared to directly immersing carbon nanotube fibers in a graphene dispersion, this invention employs a continuous coating combined with rolling and drying processes. The carbon nanotube fiber bundles continuously pass through the graphene dispersion at an appropriate speed, followed by rolling and drying. This process forms a uniform, dense, and well-oriented graphene coating layer on the carbon nanotube fiber surface. This coating layer constructs a stable interfacial transition structure on the fiber surface, enhancing the inter-fiber bonding force and frictional coordination, significantly improving uneven slippage, fuzzing, and fiber breakage during the bundling process, thereby increasing the overall density and forming stability of the fiber bundle. This invention improves both interfacial properties and the weaving toughness and wear resistance of the fiber bundle, solving problems such as fuzzing and fiber breakage in current carbon nanotube fiber weaving processes. Based on this, the uniform, dense, and well-oriented graphene layer formed in this invention can serve as a preferred site for carbon source adsorption and nucleation during chemical vapor deposition, inducing the growth of the deposited carbon interface layer along the orientation direction of the graphene sheets to form a continuous and tightly packed carbon interface layer. In the subsequent high-temperature treatment at 1800~3200℃, the graphene layer further induces the deposited carbon atoms to rearrange their orientation along their lattice direction, forming a highly oriented graphitized structure. This not only improves the degree of graphitization, lattice matching, and bonding strength between the carbon layer and the carbon nanotube fibers, but also forms a stable stress transmission channel within the fiber bundle, further enhancing the overall synergistic deformation capacity and toughness of the fiber bundle. Through the interface structure evolution induced by the graphene layer, the entire process of carbon nanotube fiber modification from monofilament interface modification to bundle structure densification and then to carbon interface layer orientation strengthening is achieved, thereby significantly improving the interface stability and mechanical-thermal integrated performance of ceramic matrix composites. This is of great significance for the preparation of ceramic matrix composites with efficient thermal conductivity and mechanical properties.

[0024] This invention offers significant technical advantages over direct reactive silicon infiltration of interface-modified carbon nanotube fiber preforms. First, a CNTF / C preform is formed using resin transfer molding (RTM) to obtain the preform. Then, reactive silicon infiltration is performed. This invention demonstrates that injecting and curing phenolic resin via RTM, followed by high-temperature pyrolysis to form a uniform and continuous carbon-based framework, effectively improves the density and overall structural stability of the preform. Furthermore, it creates a continuous carbon phase transition layer between the carbon nanotube fibers, significantly improving the wettability and interfacial compatibility between the fibers and the subsequent SiC phase. During the subsequent reactive silicon infiltration process, liquid silicon can uniformly penetrate along the carbon framework and fully react with the carbon phase, generating a fine and uniformly distributed silicon carbide matrix phase. This avoids localized over-reaction or uneven penetration, ensuring the uniformity of the ceramic matrix composite's structure and the continuity of its thermal conductivity. This multi-level interfacial structure effectively reduces interfacial thermal resistance and improves the continuity of the heat conduction path, thereby significantly enhancing the overall thermal conductivity and tensile strength of the material. In contrast, if the interface-modified carbon nanotube fiber preform is directly subjected to reactive silicon infiltration, the liquid silicon readily reacts violently with the carbon nanotube fiber surface during the infiltration process due to the large pore size of the preform and the lack of continuous carbon phase support between the fibers. This results in the formation of a locally dense silicon carbide coating layer on the fiber surface. This silicon carbide layer hinders further infiltration of liquid silicon, causing insufficient carbon reaction and uneven silicon distribution. Consequently, the formation of the silicon carbide phase in the matrix is ​​incomplete or discontinuous, ultimately leading to the coexistence of non-uniform SiC phase regions and residual silicon phase in the material microstructure, which disrupts the integrity of the overall thermal conductivity network. Furthermore, the locally excessive silicon carbide layer can also form a brittle layer at the fiber / matrix interface, causing stress concentration and significantly reducing the mechanical and thermal conductivity properties of the composite material.

[0025] According to some preferred embodiments, in step (1): the graphene dispersion is prepared by dispersing graphene in an aqueous solution containing a surfactant to obtain a graphene dispersion; specifically, for example, a certain amount of surfactant is dissolved in deionized water (e.g., 500g of deionized water) to obtain an aqueous solution containing a surfactant, and then a certain amount of graphene (e.g., 2-5g) is added to the above aqueous solution containing a surfactant, and ultrasonically treated for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion; for example, by adjusting the amount of surfactant and / or graphene added, the mass ratio of surfactant to graphene in the aqueous solution containing a surfactant can be controlled; the present invention does not specifically limit the size of the graphene, and those skilled in the art can conventionally select it, for example, preferably, the sheet diameter (particle size) of the graphene is 100-1000nm; preferably, the surfactant is polyvinylpyrrolidone (PVP) and / or sodium dodecyl sulfate (SDS); preferably, the The concentration of graphene in the graphene dispersion (graphene dispersion concentration) is 4~10 mg / g (e.g., 4, 5, 6, 7, 8, 9, or 10 mg / g); in this invention, the graphene concentration refers to the mass ratio of graphene to water in the graphene dispersion being (4~10) mg:1g; in the continuous coating combined with rolling and drying process of this invention, it is preferable to continuously pass the carbon nanotube fiber bundle through the graphene dispersion with a concentration of 4~10 mg / g at a speed of 1~4 m / min, which can achieve the desired effect on the fiber... A uniform, dense, and well-oriented graphene coating layer is formed on the fiber surface. On the one hand, continuous coating and rolling ensure that the graphene is fully spread and adhered to the fiber surface, improving the continuity and density of the interface layer. On the other hand, by controlling the fiber bundle throughput speed and graphene concentration, the thickness and uniformity of the graphene layer can be precisely adjusted, thereby enhancing the bundle aggregation performance between carbon nanotube fibers and providing a good template foundation for subsequent carbon interface layer deposition and high-temperature orientation, ultimately helping to improve the mechanical and thermal properties of ceramic matrix composites.

[0026] According to some preferred embodiments, the mass ratio of the surfactant to graphene in the aqueous solution containing the surfactant is (1~2):1 (e.g., 1:1, 1.5:1 or 2:1); and / or preferably, the graphene is dispersed in the aqueous solution containing the surfactant by ultrasonic treatment.

[0027] According to some preferred embodiments, in step (1): the drying temperature is 60~100°C (e.g., 60°C, 70°C, 80°C, 90°C or 100°C).

[0028] According to some preferred embodiments, in step (2): the method of preparing graphene-modified carbon nanotube fiber bundles into carbon nanotube fiber preforms is selected from one or more of needle punching, orthogonal triaxial weaving, stitching, fine-knitting piercing weaving, and 2.5D weaving; preferably, the 2.5D weaving is 2.5D contour weaving; in this invention, the needle-punched preform needle-punched felt and long fiber cloth can both have any carbon nanotube fiber content, the fiber volume content in the orthogonal triaxial and 2.5D woven preforms is preferably 45~50%, the warp, weft, and serration yarns can all be woven with modified carbon nanotube fibers, or one of the yarns can be modified carbon nanotube fibers to improve unidirectional thermal conductivity; the fiber cloth in the stitched preform can be a unidirectional, plain, or satin-weave fabric woven with modified carbon nanotube fibers, and the stitching yarn can be modified carbon nanotube fibers; the fiber cloth in the fine-knitting piercing preform and the Z-axis yarn can both be modified carbon nanotube fibers. In this invention, when the preform is woven using 2.5D contour weaving, a graphene-modified carbon nanotube fiber-reinforced contour ceramic matrix composite material can be obtained.

[0029] According to some preferred embodiments, when orthogonal triaxial weaving and / or 2.5D weaving is used, the carbon nanotube fiber preform is entirely woven from graphene-modified carbon nanotube fiber bundles, or is woven from a mixture of graphene-modified carbon nanotube fiber bundles and carbon fiber bundles; the present invention does not specifically limit the carbon fiber bundles, and those skilled in the art can make conventional choices.

[0030] According to some preferred embodiments, in step (2): the temperature of the chemical vapor deposition is 900~1100℃, the time is 50~150h, and the pressure is 10~150Pa; and / or the high-temperature treatment is carried out in an inert atmosphere, the time of the high-temperature treatment is 0.5~1h, and the heating rate is 200~500℃ / h, that is, the rate of heating to the high-temperature treatment temperature is 200~500℃ / h; in the present invention, for example, the preform of the deposited carbon interface layer is placed in a high-temperature furnace through which an inert gas is introduced for high-temperature treatment.

[0031] In this invention, the high-temperature treatment temperature is controlled at 1800~3200℃, the treatment time is 0.5~1h, and the heating rate is 200~500℃ / h. This can effectively promote the rearrangement of carbon atoms along their lattice direction under the induction of the graphene layer, thereby forming a highly oriented graphitized structure, improving the order and thermal conductivity continuity of the interface layer. The 0.5~1h holding time ensures that the orientation is fully carried out and that lattice distortion or interface layer coarsening is not caused by excessively long treatment.

[0032] According to some preferred embodiments, the preparation of the CNTF / C embryo in step (3) includes the following sub-steps: (a) The modified carbon nanotube fiber preform is placed in the mold cavity; (b) Phenolic resin is injected into the mold cavity and the modified carbon nanotube fiber preform is impregnated with phenolic resin, and then cured and pyrolyzed; in this invention, the impregnation time of the modified carbon nanotube fiber preform with phenolic resin is, for example, 1 to 3 hours, preferably 2 hours. (c) Repeat step (b) at least once to obtain CNTF / C embryos.

[0033] According to some preferred embodiments, the pressure of injecting phenolic resin is 2~3 MPa, the injection rate is 40~60 mL / min; the curing temperature is 220~260℃, and the time is 3~6 h; the pyrolysis is carried out under an inert atmosphere, the pyrolysis temperature is 1600~1700℃, and the pyrolysis time is 2~5 h; and / or step (b) is repeated 2~4 times to increase the C content in the preform.

[0034] According to some specific implementation methods, a modified carbon nanotube fiber preform is placed in a mold cavity, and phenolic resin is injected into the closed mold cavity under pressure or vacuum to impregnate the fiber. After curing at 240℃ for 4 hours, the preform is demolded. Pyrolysis is then performed at 1650℃ under an inert atmosphere. This resin impregnation, curing, and pyrolysis process is repeated 2-4 times to obtain a CNTF / C preform.

[0035] According to some more specific embodiments, the modified carbon nanotube fiber preform is placed in a mold with an injection port in the middle and overflow ports at the four corners. The mold is then tightened and sealed (closed) and preheated. When the mold is preheated to (80±10)℃, phenolic resin is injected to fully impregnate the modified carbon nanotube fiber preform. The injection pressure and injection speed are 2.5MPa and 50mL / min, respectively. Then, the preform is cured at (240±5)℃ for 4h. When the mold temperature is no higher than 60℃, the composite material layer is removed from the mold. The preform is then pyrolyzed at 1650℃ under a nitrogen atmosphere to obtain the CNTF / C preform.

[0036] According to some preferred embodiments, in step (3): silicon and / or zirconium silicon alloy is used as a melting agent; and / or the temperature of the reaction melting is 1600~1700℃ and the time is 2~4h.

[0037] According to some preferred embodiments, the ceramic precursor is one or more of zirconium silicon precursor, silicon carbide precursor, zirconium carbide precursor, and hafnium carbide precursor. The present invention does not specifically limit the ceramic precursors such as zirconium silicon precursor, silicon carbide precursor, zirconium carbide precursor, and hafnium carbide precursor, nor does it specifically limit the corresponding impregnation pyrolysis process. Those skilled in the art can choose conventionally.

[0038] In a second aspect, the present invention provides a graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material prepared by the preparation method described in the first aspect of the present invention.

[0039] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments. The present invention may have many other embodiments, and those skilled in the art can make various corresponding changes and modifications based on the present invention without departing from its spirit and essence; however, these corresponding changes and modifications should all fall within the scope of protection of the appended claims. Unless otherwise specified, the experimental methods used in the following embodiments and comparative examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments and comparative examples are commercially available. The following embodiments and comparative examples use the same carbon nanotube fibers and phenolic resin. Example 1

[0040] (1) Dissolve 2.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 2.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 5mg / g; the mass ratio of surfactant to graphene is 1:1.

[0041] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 2 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0042] (3) The graphene-modified carbon nanotube fiber bundles and T300 carbon fiber bundles are used together to weave a preform. A preform with a normal high thermal conductivity structure (i.e., carbon nanotube fiber preform) is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%, of which the normal (Z-direction) fiber is graphene-modified carbon nanotube fiber bundle, and the Z-direction fiber volume content in the preform is 18.5%; the warp and weft (X-direction and Y-direction) fibers are T300 carbon fiber bundles.

[0043] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0044] (5) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the CNTF / C preform.

[0045] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material (also referred to as CNTF / C-SiC ceramic matrix composite material).

[0046] The room temperature tensile strength of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 238 MPa, the thermal conductivity in the X direction was 12 W / (m·K), the thermal conductivity in the Y direction was 16 W / (m·K), and the thermal conductivity in the Z direction was 145 W / (m·K). Example 2

[0047] (1) Dissolve 5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 10mg / g; the mass ratio of surfactant to graphene is 1:1.

[0048] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 2 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0049] (3) The graphene-modified carbon nanotube fiber bundles and T300 carbon fiber bundles are used together to weave a preform. A preform with a normal high thermal conductivity structure (i.e., carbon nanotube fiber preform) is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%, of which the normal (Z-direction) fiber is graphene-modified carbon nanotube fiber bundle, and the Z-direction fiber volume content in the preform is 18.5%; the warp and weft (X-direction and Y-direction) fibers are T300 carbon fiber bundles.

[0050] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0051] (5) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the CNTF / C preform.

[0052] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material (also referred to as CNTF / C-SiC ceramic matrix composite material).

[0053] The room temperature tensile strength of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 253 MPa, the thermal conductivity in the X direction was 13 W / (m·K), the thermal conductivity in the Y direction was 18 W / (m·K), and the thermal conductivity in the Z direction was 157 W / (m·K). Example 3

[0054] (1) Dissolve 2.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 2.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 5mg / g; the mass ratio of surfactant to graphene is 1:1.

[0055] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 2 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0056] (3) All graphene-modified carbon nanotube fiber bundles are used to weave the preform. The preform (i.e., carbon nanotube fiber preform) with a three-dimensional high thermal conductivity structure is formed by fine weaving and piercing weaving process. Specifically, plain weave fabric is used in the inner surface, and Z-direction modified carbon nanotube fibers are pierced through the inner surface layer by fine weaving and piercing process. The total fiber volume content of the preform is 48%, of which the content of X-direction modified carbon nanotube fibers in the inner surface is 20%, the content of Y-direction modified carbon nanotube fibers is 20%, and the content of Z-direction modified carbon nanotube fibers is 8%.

[0057] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0058] (5) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the CNTF / C preform.

[0059] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material (also referred to as CNTF / C-SiC ceramic matrix composite material).

[0060] The room temperature tensile strength of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 288 MPa, the thermal conductivity in the X direction was 156 W / (m·K), the thermal conductivity in the Y direction was 151 W / (m·K), and the thermal conductivity in the Z direction was 73 W / (m·K). Example 4

[0061] (1) Dissolve 2.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 2.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 5mg / g; the mass ratio of surfactant to graphene is 1:1.

[0062] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 4 m / min, it is subjected to roller pressing treatment, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0063] (3) The graphene-modified carbon nanotube fiber bundles and T300 carbon fiber bundles are used together to weave a preform. A preform with a normal high thermal conductivity structure (i.e., carbon nanotube fiber preform) is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%, of which the normal (Z-direction) fiber is graphene-modified carbon nanotube fiber bundle, and the Z-direction fiber volume content in the preform is 18.5%; the warp and weft (X-direction and Y-direction) fibers are T300 carbon fiber bundles.

[0064] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0065] (5) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the CNTF / C preform.

[0066] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material (also referred to as CNTF / C-SiC ceramic matrix composite material).

[0067] The room temperature tensile strength of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 216 MPa, the thermal conductivity in the X direction was 9 W / (m·K), the thermal conductivity in the Y direction was 11 W / (m·K), and the thermal conductivity in the Z direction was 122 W / (m·K). Example 5

[0068] (1) Dissolve 2.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 2.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 5mg / g; the mass ratio of surfactant to graphene is 1:1.

[0069] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 4 m / min, it is subjected to roller pressing treatment, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0070] (3) The graphene-modified carbon nanotube fiber bundles and T300 carbon fiber bundles are used together to weave a preform. A preform with a normal high thermal conductivity structure (i.e., carbon nanotube fiber preform) is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%, of which the normal (Z-direction) fiber is graphene-modified carbon nanotube fiber bundle, and the Z-direction fiber volume content in the preform is 18.5%; the warp and weft (X-direction and Y-direction) fibers are T300 carbon fiber bundles.

[0071] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0072] (5) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the process of resin impregnation, curing, and pyrolysis once to obtain the CNTF / C preform.

[0073] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain the graphene modified carbon nanotube fiber reinforced ceramic matrix composite material (also referred to as CNTF / C-SiC ceramic matrix composite material).

[0074] The room temperature tensile strength of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 188 MPa, the thermal conductivity in the X direction was 8 W / (m·K), the thermal conductivity in the Y direction was 9 W / (m·K), and the thermal conductivity in the Z direction was 98 W / (m·K). Example 6

[0075] Example 6 is basically the same as Example 1, except that: (1) Dissolve 1g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 1g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 2mg / g; the mass ratio of surfactant to graphene is 1:1.

[0076] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 0.5 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0077] The thermal conductivity of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 9 W / (m·K) in the X direction, 12 W / (m·K) in the Y direction, and 132 W / (m·K) in the Z direction. Example 7

[0078] Example 7 is basically the same as Example 1, except that: (1) Dissolve 7.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 7.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 15mg / g; the mass ratio of surfactant to graphene is 1:1.

[0079] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 5 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0080] The thermal conductivity of the CNTF / C-SiC ceramic matrix composite material prepared in this embodiment was measured to be 8 W / (m·K) in the X direction, 10 W / (m·K) in the Y direction, and 127 W / (m·K) in the Z direction. Example 8

[0081] (1) Dissolve 2.5g of surfactant sodium dodecyl sulfate (SDS) in 500g of deionized water to obtain an aqueous solution containing surfactant; add 2.5g of graphene powder with a particle size of 500nm to the above aqueous solution and sonicate it for 1 hour under ultrasonic action to obtain a uniformly dispersed graphene dispersion with a concentration of 5mg / g; the mass ratio of surfactant to graphene is 1:1.

[0082] (2) After passing the carbon nanotube fiber bundle through the above graphene dispersion at a speed of 2 m / min, it is subjected to roller pressing, then washed with water to remove the surfactant, and dried and wound up by a drying roller at a temperature of 80°C to obtain graphene modified carbon nanotube fiber bundle.

[0083] (3) All graphene-modified carbon nanotube fiber bundles are used to weave the preform. The preform (i.e., carbon nanotube fiber preform) with a three-dimensional high thermal conductivity structure is formed by fine weaving and piercing weaving process. Specifically, plain weave fabric is used in the inner surface, and Z-direction modified carbon nanotube fibers are pierced through the inner surface layer by fine weaving and piercing process. The total fiber volume content of the preform is 48%, of which the content of X-direction modified carbon nanotube fibers in the inner surface is 20%, the content of Y-direction modified carbon nanotube fibers is 20%, and the content of Z-direction modified carbon nanotube fibers is 8%.

[0084] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0085] (5) Using zirconium silicon precursor as reactant, a product with a density of 2.56 g / cm³ was prepared by precursor impregnation pyrolysis. 3 Graphene-modified carbon nanotube fiber-reinforced ceramic matrix composites.

[0086] The room temperature tensile strength of the graphene-modified carbon nanotube fiber reinforced ceramic matrix composite material prepared in this embodiment was measured to be 288 MPa, the thermal conductivity in the X direction was 148 W / (m·K), the thermal conductivity in the Y direction was 146 W / (m·K), and the thermal conductivity in the Z direction was 77 W / (m·K). Comparative Example 1

[0087] (1) Carbon nanotube fiber bundles and T300 carbon fiber bundles are used together to weave a preform. A preform with a normal high thermal conductivity structure (i.e., carbon nanotube fiber preform) is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%, of which the normal (Z-direction) fiber is made of carbon nanotube fiber bundles and the Z-direction fiber volume content in the preform is 18.5%; the warp and weft (X-direction and Y-direction) fibers are made of T300 carbon fiber bundles.

[0088] (2) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (1) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reaction furnace is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with an inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified carbon nanotube fiber preform.

[0089] (3) Place the modified carbon nanotube fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified carbon nanotube fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the process of resin impregnation, curing, and pyrolysis once to obtain the CNTF / C preform.

[0090] (4) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction melting and infiltration is carried out at 1650℃ for 2 hours under nitrogen protection to obtain carbon nanotube fiber reinforced ceramic matrix composite material.

[0091] The room temperature tensile strength of the carbon nanotube fiber reinforced ceramic matrix composite material prepared in this comparative example was measured to be 165 MPa, the thermal conductivity in the X direction was 6 W / (m·K), the thermal conductivity in the Y direction was 7 W / (m·K), and the thermal conductivity in the Z direction was 68 W / (m·K). Comparative Example 2

[0092] (1) A three-dimensional orthogonal structure preform woven with T300 carbon fiber is used, and the fiber volume content of the preform is 48%.

[0093] (2) A carbon interface layer is prepared on the surface of the preform obtained in step (1) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reactor is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified fiber preform.

[0094] (3) Place the modified fiber preform into a mold, with an injection port in the middle and overflow ports at the four corners. Secure and seal the mold and preheat it to 80°C. Then, inject phenolic resin. The injection pressure and injection speed are 2.5 MPa and 50 mL / min, respectively, to impregnate the modified fiber preform with phenolic resin for 2 hours. Then, cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold. Pyrolyze it at 1650°C for 2 hours in a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the carbon fiber / C preform.

[0095] (4) The silicon powder is evenly spread and embedded in the carbon fiber / C preform, and the reaction melting and infiltration is carried out at 1650℃ for 2 hours under nitrogen protection to obtain carbon fiber reinforced ceramic matrix composite material.

[0096] The thermal conductivity of the carbon fiber reinforced ceramic matrix composite material prepared in this comparative example was measured to be 6 W / (m·K) in the X direction, 8 W / (m·K) in the Y direction, and 9 W / (m·K) in the Z direction. Comparative Example 3

[0097] (1) Same as step (1) in Example 1.

[0098] (2) Same as step (1) in Example 1.

[0099] (3) Same as step (1) in Example 1.

[0100] (4) is the same as step (4) in Example 1.

[0101] (5) The modified carbon nanotube fiber preform obtained in step (4) is uniformly spread with silicon powder and reacted and infiltrated at 1650°C for 2 hours under nitrogen protection to obtain carbon nanotube fiber reinforced ceramic matrix composite material.

[0102] The room temperature tensile strength of the carbon nanotube fiber reinforced ceramic matrix composite material prepared in this comparative example was measured to be 167 MPa, the thermal conductivity in the X direction was 6 W / (m·K), the thermal conductivity in the Y direction was 7 W / (m·K), and the thermal conductivity in the Z direction was 76 W / (m·K). Comparative Example 4

[0103] (1) Same as step (1) in Example 1.

[0104] (2) Same as step (1) in Example 1.

[0105] (3) Same as step (1) in Example 1.

[0106] (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reactor is 50Pa, so as to obtain the modified carbon nanotube fiber preform.

[0107] (5) Same as step (1) of Example 1.

[0108] (6) The silicon powder is evenly spread and embedded in the CNTF / C preform, and the reaction is carried out at 1650℃ for 2 hours under nitrogen protection to obtain carbon nanotube fiber reinforced ceramic matrix composite material.

[0109] The thermal conductivity of the carbon nanotube fiber reinforced ceramic matrix composite material prepared in this comparative example was measured to be 6 W / (m·K) in the X direction, 8 W / (m·K) in the Y direction, and 96 W / (m·K) in the Z direction. Comparative Example 5

[0110] (1) Carbon nanotube fibers are provided and subjected to hydroxylation pretreatment to obtain hydroxylated pretreated carbon nanotube fibers; the hydroxylation pretreatment is as follows: the carbon nanotube fibers are immersed in a mixed solution of 98% concentrated sulfuric acid and 30% hydrogen peroxide with a volume ratio of 7:3, and kept at 80℃ in an oil bath for 1.0 h. After the treatment, the fibers are removed and immersed in distilled water at room temperature for 0.5 h, and finally dried to obtain hydroxylated pretreated carbon nanotube fibers.

[0111] (2) Preparation of graphene oxide interface layer: Prepare an aqueous solution of graphene oxide with a concentration of 0.6 mg / mL, place the hydroxylated pretreated carbon nanotube fibers in the aqueous solution of graphene oxide and let stand for 30 min, then pull out the solution to obtain carbon nanotube fibers with graphene oxide interface layer.

[0112] (3) High-temperature annealing technique for preparing graphene interface layer: The carbon nanotube fibers with graphene oxide interface layer are placed in a high-temperature furnace, the vacuum is drawn to 20 Pa, and argon gas is continuously introduced. The annealing temperature is set to 1000℃ and the annealing time is set to 2h. After annealing, the temperature is reduced to room temperature at a rate of 0.1℃ / min to obtain carbon nanotube fibers with graphene interface layer.

[0113] (4) The carbon nanotube fibers with graphene interface layer and T300 carbon fiber are used together to weave a preform. The preform is formed by a triaxial orthogonal weaving process. The total fiber volume content of the preform is 48%. The normal (Z-direction) fiber is carbon nanotube fiber with graphene interface layer. The Z-direction fiber has a volume content of 18.5% in the preform. The warp and weft (X-direction and Y-direction) fibers are T300 carbon fiber.

[0114] (5) A carbon interface layer is prepared on the surface of the preform obtained in step (4) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reactor is 50Pa. The preform with the carbon interface layer is placed in a high-temperature furnace with inert gas (nitrogen atmosphere) for high-temperature treatment. The temperature is 2400℃, the high-temperature treatment time is 45min, and the heating rate is 500℃ / h to obtain the modified fiber preform.

[0115] (6) Place the modified fiber preform into a mold, with an injection port in the center and overflow ports at the four corners. Secure and seal the mold and preheat it to 80°C. Inject phenolic resin at the injection pressure and injection speed of 2.5 MPa and 50 mL / min, respectively, to impregnate the modified fiber preform with phenolic resin for 2 hours. Then cure it at 240°C for 4 hours. When the mold temperature is below 60°C, remove the composite material layer from the mold and pyrolyze it at 1650°C for 2 hours under a nitrogen atmosphere. Repeat the resin impregnation, curing, and pyrolysis process three times to obtain the preform.

[0116] (7) The silicon powder is evenly spread and embedded in the preform, and the reaction is carried out at 1650°C for 2 hours under nitrogen protection to obtain the modified carbon nanotube fiber reinforced ceramic matrix composite material.

[0117] The thermal conductivity of the modified carbon nanotube fiber reinforced ceramic matrix composite material prepared in this comparative example was measured to be 10 W / (m·K) in the X direction, 13 W / (m·K) in the Y direction, and 129 W / (m·K) in the Z direction. Comparative Example 6

[0118] Comparative Example 6 is basically the same as Example 1, except that: (4) A carbon interface layer is prepared on the surface of the carbon nanotube fiber preform obtained in step (3) by chemical vapor deposition. The chemical vapor deposition reaction temperature is 900℃, the holding time is 100h, and the pressure in the reactor is 50Pa; 100Pa; then the preform with the carbon interface layer deposited is subjected to instantaneous high temperature treatment at 2400℃ for 300s under nitrogen protection to obtain the modified carbon nanotube fiber preform.

[0119] The thermal conductivity of the graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material prepared in this comparative example was measured to be 7 W / (m·K) in the X direction, 8 W / (m·K) in the Y direction, and 108 W / (m·K) in the Z direction.

[0120] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material, characterized in that, The method includes the following steps: (1) Carbon nanotube fiber bundles are passed through graphene dispersion at a speed of 1~4 m / min, and then subjected to rolling, washing and drying to form a graphene layer on the fiber surface, thus obtaining graphene modified carbon nanotube fiber bundles. (2) Graphene-modified carbon nanotube fiber bundles are prepared into carbon nanotube fiber preforms, and then carbon interface layers are prepared on the surface of the carbon nanotube fiber preforms by chemical vapor deposition. After being treated at high temperature of 1800~3200℃, modified carbon nanotube fiber preforms are obtained. (3) The modified carbon nanotube fiber preform and phenolic resin are subjected to RTM process to obtain CNTF / C preform, and then the CNTF / C preform is reacted and infiltrated with a melt infiltrator to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material; or the ceramic precursor is reacted with the modified carbon nanotube fiber preform by impregnation pyrolysis method to obtain graphene modified carbon nanotube fiber reinforced ceramic matrix composite material.

2. The preparation method according to claim 1, characterized in that, In step (1): The graphene dispersion is prepared by dispersing graphene in an aqueous solution containing a surfactant to obtain the graphene dispersion. Preferably, the surfactant is polyvinylpyrrolidone and / or sodium dodecyl sulfate; Preferably, the concentration of graphene in the graphene dispersion is 4~10 mg / g; Preferably, the mass ratio of the surfactant to graphene in the aqueous solution containing the surfactant is (1~2):1; Preferably, graphene is dispersed in an aqueous solution containing a surfactant by ultrasonic treatment; and / or The drying temperature is 60~100℃.

3. The preparation method according to claim 1, characterized in that, In step (2): The method for preparing graphene-modified carbon nanotube fiber bundles into carbon nanotube fiber preforms is selected from one or more of the following: needle punching, orthogonal triaxial weaving, stitching, fine weaving and puncture weaving, and 2.5D weaving. Preferably, the 2.5D weave is a 2.5D contour weave.

4. The preparation method according to claim 3, characterized in that: When orthogonal triaxial weaving and / or 2.5D contour weaving are used, the carbon nanotube fiber preform is entirely woven from graphene-modified carbon nanotube fiber bundles, or is woven from a mixture of graphene-modified carbon nanotube fiber bundles and carbon fiber bundles.

5. The preparation method according to claim 1, characterized in that, In step (2): The chemical vapor deposition is performed at a temperature of 900–1100 °C, a time of 50–150 h, and a pressure of 10–150 Pa; and / or The high-temperature treatment is carried out under an inert atmosphere for a duration of 0.5 to 1 hour, with a heating rate of 200 to 500 °C / hour.

6. According to the preparation method of claim 1, the preparation of the CNTF / C embryo in step (3) includes the following sub-steps: (a) The modified carbon nanotube fiber preform is placed in the mold cavity; (b) Phenolic resin is injected into the mold cavity and the modified carbon nanotube fiber preform is impregnated with phenolic resin, followed by curing and pyrolysis. (c) Repeat step (b) at least once to obtain CNTF / C embryos.

7. The preparation method according to claim 6, characterized in that: The injection pressure of the phenolic resin is 2~3MPa, and the injection rate is 40~60mL / min; The impregnation time of the phenolic resin modified carbon nanotube fiber preform is 1-3 hours, preferably 2 hours; The curing temperature is 220~260℃, and the time is 3~6h; The pyrolysis is carried out under an inert atmosphere, at a temperature of 1600~1700℃, and for a time of 2~5 hours; and / or Repeat step (b) 2 to 4 times.

8. The preparation method according to claim 1, characterized in that, In step (3): Using silicon and / or zirconium-silicon alloys as infiltration agents; and / or The reaction melting temperature is 1600~1700℃, and the time is 2~4h.

9. The preparation method according to claim 1, characterized in that, In step (3): The ceramic precursor is one or more of zirconium silicon precursor, silicon carbide precursor, zirconium carbide precursor, and hafnium carbide precursor.

10. A graphene-modified carbon nanotube fiber-reinforced ceramic matrix composite material prepared by any one of claims 1 to 9.