A wide temperature range reusable high thermal conductivity composite material and preparation method thereof

Abstract

The present invention relates to a wide temperature range reusable high thermal conductivity composite material and a preparation method thereof. The preform used in the wide temperature range reusable high thermal conductivity composite material is a high thermal conductivity carbon fiber preform, and the fiber surface of the preform has an anti-oxidation alternating interface layer, and the anti-oxidation alternating interface layer is formed by alternating n layers of silicon carbide interface layer and n layers of boron nitride nanosheet interface layer; the wide temperature range reusable high thermal conductivity composite material has a wide temperature range anti-oxidation ceramic matrix, and the wide temperature range anti-oxidation ceramic matrix includes a SiC matrix, a ZrC matrix and a SiCBN matrix; the wide temperature range reusable high thermal conductivity composite material has an anti-oxidation alternating ceramic coating, and the anti-oxidation alternating ceramic coating is formed by alternating m layers of silicon carbide coating and m layers of boron nitride nanosheet coating. The wide temperature range reusable high thermal conductivity composite material of the present invention has the characteristics of high thermal conductivity, high matrix density, and excellent wide temperature range reusability.

Description

Technical Field

[0001] The present invention belongs to the field of composite materials and preparation technology, and in particular relates to a high-thermal-conductivity composite material that is reusable over a wide temperature range and a preparation method thereof. Background Art

[0002] Wide temperature range, high temperature resistant, reusable materials are one of the key bottlenecks restricting the development of reusable products. Traditional composite materials have low thermal conductivity, insufficient density, and the pyrolytic carbon interface layer is easily oxidized and fails, which cannot meet the requirements of reusable performance. Wide temperature range reusable thermal conductive composite materials can transfer heat evenly, increase the heat radiation area, and reduce the temperature gradient. At the same time, the material is dense and has a wide temperature range synergistic antioxidant ability, which can meet the needs of wide temperature range reusability. However, the wide temperature range, high temperature resistant, reusable materials in the existing technology have problems such as a narrow wide temperature range of use, a short reusable service life, and thermal conductivity that needs to be further improved.

[0003] Therefore, it is very necessary to provide a wide temperature range reusable high thermal conductivity composite material and its preparation method to provide thermal protection materials and preparation technology support for subsequent applications. Summary of the Invention

[0004] In order to solve one or more technical problems existing in the prior art, the present invention provides a high thermal conductivity composite material that is reusable over a wide temperature range and a preparation method thereof.

[0005] In a first aspect, the present invention provides a wide-temperature-range reusable high-thermal-conductivity composite material. The preform used in the wide-temperature-range reusable high-thermal-conductivity composite material is a high-thermal-conductivity carbon fiber preform. The fiber surface of the preform has an anti-oxidation alternating interface layer, and the anti-oxidation alternating interface layer is formed by alternating n layers of silicon carbide interface layers and n layers of boron nitride nanosheet interface layers; the wide-temperature-range reusable high-thermal-conductivity composite material has a wide-temperature-range anti-oxidation ceramic matrix, and the wide-temperature-range anti-oxidation ceramic matrix includes a SiC matrix, a ZrC matrix and a SiCBN matrix; the wide-temperature-range reusable high-thermal-conductivity composite material has an anti-oxidation alternating ceramic coating, and the anti-oxidation alternating ceramic coating is formed by alternating m layers of silicon carbide coating and m layers of boron nitride nanosheet coating.

[0006] Preferably, the density of the wide temperature range reusable high thermal conductivity composite material is 2.4 to 3.2 g / cm 3 ; and / or the wide temperature range reusable high thermal conductivity composite material has the characteristics of wide temperature range reusability and high thermal conductivity.

[0007] In a second aspect, the present invention provides a method for preparing a reusable high thermal conductivity composite material having a wide temperature range, the method comprising the following steps:

[0008] (1) Preparing a high thermal conductivity carbon fiber preform;

[0009] (2) alternately depositing a silicon carbide interface layer and a boron nitride nanosheet interface layer on the fiber surface of the high thermal conductivity carbon fiber preform by chemical vapor deposition until a preset thickness or a preset number of layers is reached to obtain an intermediate body containing an anti-oxidation alternating interface layer;

[0010] (3) performing a first densification on the intermediate body by a PIP process of impregnation / curing / cracking using a polycarbosilane ceramic precursor solution and a zirconium-based ceramic precursor solution as impregnation liquids, to obtain a first densified composite material;

[0011] (4) subjecting the first densified composite material to a high-temperature treatment, and then subjecting the first densified composite material to a second densification by a PIP process of impregnation / curing / cracking using a polyborosilazane ceramic precursor solution as an impregnation liquid to obtain a second densified composite material;

[0012] (5) Alternately depositing a silicon carbide coating and a boron nitride nanosheet coating on the surface of the second densified composite material by chemical vapor deposition until a preset thickness or a preset number of layers is reached to obtain a wide temperature range reusable high thermal conductivity composite material; in steps (2) and (5), depositing the boron nitride nanosheet interface layer and the boron nitride nanosheet coating in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia, wherein the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is (18-20): (1-2): (1-2): (1-1.5), and the deposition temperature is 900-1100°C.

[0013] Preferably, in step (1): a carbon fiber preform is formed by mixing high thermal conductivity carbon fiber and polyacrylonitrile-based carbon fiber or a carbon fiber preform is formed by weaving high thermal conductivity carbon fiber, and then graphitizing the preform to obtain a high thermal conductivity carbon fiber preform; preferably, the volume fraction of carbon fiber in the high thermal conductivity carbon fiber preform is 30-40%, and the density of the high thermal conductivity carbon fiber preform is 0.6-0.9 g / cm 3 ; Preferably, the temperature of the graphitization treatment is 2800-3200°C and the time is 0.5-1h.

[0014] Preferably, in step (1), the preparation of the high thermal conductivity carbon fiber preform comprises the following sub-steps:

[0015] (a) dispersing mesophase pitch-based carbon fiber bundles by mechanical vibration and / or ultrasonic vibration, and then fixing them with hot melt wire to obtain a unidirectional pitch-based carbon fiber cloth;

[0016] (b) After laminating unidirectional asphalt-based carbon fiber cloth, polyacrylonitrile-based carbon fiber is used to sew them together to obtain a high thermal conductivity carbon fiber preform.

[0017] Preferably, in step (2): the number of layers of the silicon carbide interface layer and the boron nitride nanosheet interface layer are both n layers, n is 2 to 4 and n is a natural number; when depositing the silicon carbide interface layer, the deposition temperature is 1000 to 1100°C, the thickness of the single-layer silicon carbide interface layer is 0.1 to 0.2 μm; the thickness of the single-layer boron nitride nanosheet interface layer is 0.1 to 0.2 μm; preferably, the thickness ratio of the single-layer silicon carbide interface layer to the single-layer boron nitride nanosheet interface layer is (0.8 to 1.2):1.

[0018] Preferably, in step (3): first, a polycarbosilane ceramic precursor solution is used as an impregnation liquid to perform 3 to 5 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 900 to 1200°C, and the time for each cracking is 2 to 4 hours, and then a zirconium-based ceramic precursor solution is used as an impregnation liquid to perform 5 to 10 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 1400 to 1500°C, and the time for each cracking is 2 to 4 hours.

[0019] Preferably, in step (4): the temperature of the high temperature treatment is 1600°C to 2000°C, the time is 3 to 5 hours, and / or the high temperature treatment is carried out under an inert atmosphere; and / or a polyborosilazane ceramic precursor solution is used as an impregnation liquid to carry out 8 to 15 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 1000 to 1300°C, and the time of each cracking is 2 to 4 hours.

[0020] Preferably, in step (5): the number of layers of the silicon carbide coating and the boron nitride nanosheet coating is m, m is 2 to 4 and is a natural number; when depositing the silicon carbide coating, the deposition temperature is 1000 to 1100°C, the thickness of the single-layer silicon carbide coating is 15 to 20 μm; the thickness of the single-layer boron nitride nanosheet coating is 15 to 20 μm; preferably, the thickness ratio of the single-layer silicon carbide coating to the single-layer boron nitride nanosheet coating is (0.8 to 1.2): 1; preferably, the silicon carbide coating and the boron nitride nanosheet coating are alternately deposited to form an antioxidant alternating ceramic coating, and the total thickness of the antioxidant alternating ceramic coating is 60 to 160 μm.

[0021] Preferably, the polycarbosilane ceramic precursor solution, the zirconium-based ceramic precursor solution and the polyborosilazane ceramic precursor solution all contain boron nitride nanosheets; the mass fraction of the boron nitride nanosheets in the polycarbosilane ceramic precursor solution is 2-3%; the mass fraction of the boron nitride nanosheets in the zirconium-based ceramic precursor solution is 4-6%; the mass fraction of the boron nitride nanosheets in the polyborosilazane ceramic precursor solution is 2-3%; preferably, the boron nitride nanosheets have a sheet diameter of 1-2 μm and a thickness of 60-120 nm.

[0022] In a third aspect, the present invention provides a high thermal conductivity composite material that is reusable over a wide temperature range and is prepared by the preparation method described in the second aspect of the present invention.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) The present invention combines high thermal conductivity carbon fiber, wide temperature range anti-oxidation interface layer and multi-component wide temperature range anti-oxidation ceramic matrix to achieve the reusability of the material at 700℃~1500℃; the multi-layer alternating anti-oxidation alternating interface layer and anti-oxidation alternating ceramic coating not only have wide temperature range anti-oxidation characteristics, but even if the outermost layer fails due to oxidation, the inner layer can still play a role in protecting the fiber, and has a long repeatable life and high reliability; in the present invention, the process of preparing boron nitride by chemical vapor deposition is adjusted so that the anti-oxidation alternating interface layer is formed by alternating silicon carbide interface layer and boron nitride nanosheet interface layer, and the anti-oxidation alternating ceramic coating is formed by alternating silicon carbide coating and boron nitride nanosheet coating. The present invention finds that the combination of boron nitride nanosheets and silicon carbide can significantly improve the thermal conductivity of the interface layer and the coating, which will help to conduct heat more effectively and improve the composite The overall thermal conductivity of the material makes it more suitable for applications requiring high thermal conductivity. In the antioxidant alternating interface layer and the antioxidant alternating ceramic coating of the present invention, the formation of the boron nitride nanosheet interface layer and the boron nitride nanosheet coating can significantly improve the thermal conductivity, antioxidant performance and wide temperature range reusability of the material compared to ordinary boron nitride interface layers and boron nitride coatings, making it more suitable for applications in high-temperature environments. This interface layer structure and coating structure can provide better thermal conduction and antioxidant performance, which helps the material to exhibit better stability under extreme conditions. The antioxidant alternating interface layer and antioxidant alternating ceramic coating in the present invention can better protect carbon fibers from high-temperature oxidation or oxidation in the atmosphere, which helps to extend the service life of the composite material. The high thermal conductivity composite material prepared by the present invention can be reused in a wider temperature range.

[0025] (2) The present invention adopts chemical vapor deposition to prepare an antioxidant alternating interface layer on the fiber surface of a high thermal conductivity carbon fiber preform and an antioxidant alternating ceramic coating on the surface of a composite material. The components and structures of the interface layer and the ceramic coating are similar, and the thermal expansion coefficients are similar. The thermal stress generated during high-low temperature use is small, and cracking is not easy to occur, which is conducive to ensuring the high-temperature mechanical properties of the material. The present invention effectively solves the problems existing in the prior art, such as low thermal conductivity, insufficient density, easy oxidation failure of the pyrolytic carbon interface layer or other interface layers, and inability to meet the requirements of reusability.

[0026] (3) In some preferred embodiments of the present invention, when the PIP process of impregnation / curing / cracking is carried out, the polycarbosilane ceramic precursor solution, the zirconium-based ceramic precursor solution and the polyborosilazane ceramic precursor solution all contain appropriate amounts of boron nitride nanosheets, which is beneficial to improving the high thermal conductivity and antioxidant properties of the material, and helps to improve the wide temperature range reusability of the material; in addition, the present invention uses different ceramic precursors for densification and controls the content of boron nitride nanosheets in each ceramic precursor, which can effectively adjust the thermal matching and high-temperature mechanical properties of the composite material, which helps to alleviate the thermal stress and deformation problems of the material under high temperature conditions, improves the thermal stability and thermal expansion matching of the material in a high temperature environment, and also helps to improve the wide temperature range reusability of the material. DETAILED DESCRIPTION

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In a first aspect, the present invention provides a wide-temperature-range reusable high-thermal-conductivity composite material, wherein the preform used in the wide-temperature-range reusable high-thermal-conductivity composite material is a high-thermal-conductivity carbon fiber preform, and the fiber surface of the preform has an anti-oxidation alternating interface layer, and the anti-oxidation alternating interface layer (also referred to as an anti-oxidation multilayer interface layer) is alternately formed by n layers of silicon carbide interface layers and n layers of boron nitride nanosheet interface layers; the wide-temperature-range reusable high-thermal-conductivity composite material has a wide-temperature-range anti-oxidation ceramic matrix, and the wide-temperature-range anti-oxidation ceramic matrix includes a SiC matrix, a ZrC matrix and a SiCBN matrix; the wide-temperature-range reusable high-thermal-conductivity composite material has an anti-oxidation alternating ceramic coating, and the anti-oxidation alternating ceramic coating (also referred to as a high-density alternating ceramic coating) is alternately formed by m layers of silicon carbide coating and m layers of boron nitride nanosheet coating; in the present invention, n and m are both greater than or equal to 1, and n and m are natural numbers, and n and m can have the same or different values. Preferably, n is 2 to 4 and m is 2 to 4.

[0029] In the present invention, the wide temperature range reusable high thermal conductivity composite material is, for example, (SiC / BN nanosheets) m Coating C f / (SiC / BN nanosheets) n / SiC-ZrC-SiCBN composite material, the density of the composite material is 2.4~3.2g / cm 3The composite material uses high thermal conductivity carbon fiber, anti-oxidation alternating multi-layer interface layer, wide temperature range anti-oxidation ceramic matrix and high-density alternating ceramic coating, so that the composite material has the characteristics of high thermal conductivity in a wide temperature range and reusability. Compared with the materials in the existing technology, it has high thermal conductivity, high matrix density, interface layer and coating are not easy to oxidize and fail, and excellent reusability in a wide temperature range.

[0030] According to some preferred embodiments, the density of the wide temperature range reusable high thermal conductivity composite material is 2.4 to 3.2 g / cm 3 ; and / or the wide temperature range reusable high thermal conductivity composite material has the characteristics of wide temperature range reusability and high thermal conductivity.

[0031] In a second aspect, the present invention provides a method for preparing a reusable high thermal conductivity composite material having a wide temperature range, the method comprising the following steps:

[0032] (1) Preparing a high thermal conductivity carbon fiber preform; In the present invention, for example, mesophase pitch-based carbon fibers (high thermal conductivity carbon fibers) can be used alone or mixed with polyacrylonitrile-based (PAN-based) carbon fibers to weave into a 2.5D woven structure and then subjected to high-temperature graphitization treatment to obtain the high thermal conductivity carbon fiber preform;

[0033] (2) Alternately depositing a silicon carbide interface layer and a boron nitride nanosheet interface layer on the fiber surface of the high thermal conductivity carbon fiber preform by chemical vapor deposition until a preset thickness or a preset number of layers are reached to obtain an anti-oxidation alternating interface layer (SiC / BN nanosheet) n an intermediate body; alternately depositing a silicon carbide interface layer and a boron nitride nanosheet interface layer to form the anti-oxidation alternating interface layer; in step (2), depositing the boron nitride nanosheet interface layer in an atmosphere comprising nitrogen, hydrogen, boron trichloride gas and ammonia, wherein the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is (18-20): (1-2): (1-2): (1-1.5), and the deposition temperature is 900-1100° C. (e.g., 900° C., 950° C., 1000° C., 1050° C. or 1100° C.);

[0034] (3) using polycarbosilane ceramic precursor solution and zirconium-based ceramic precursor solution as impregnation liquids in sequence, performing a first densification on the intermediate body through a PIP process of impregnation / curing / cracking to obtain a first densified composite material; in the present invention, the polycarbosilane ceramic precursor solution is prepared by: mixing polycarbosilane with xylene to obtain a polycarbosilane ceramic precursor solution, wherein the mass percentage of polycarbosilane in the polycarbosilane ceramic precursor solution is 50-70%; in the present invention, the zirconium-based ceramic precursor solution is prepared, for example, by: mixing zirconium carbide ceramic precursor with xylene to obtain a zirconium-based ceramic precursor solution, wherein the mass fraction of zirconium carbide ceramic precursor in the zirconium-based ceramic precursor solution is 50-70wt%; the present invention does not specifically limit the source of the zirconium carbide ceramic precursor, and can use a product that can be directly purchased or synthesized by an existing method; in the present invention, for example, with reference to Chinese patent application CN1121 The preparation method of the zirconium carbide ceramic precursor in 42471A synthesizes the zirconium carbide ceramic precursor. Specifically, the preparation of the zirconium carbide ceramic precursor is as follows: 5.7 parts of polyvinyl alcohol and 185 parts of distilled water are added to a three-necked flask equipped with a magnetic stirrer, a spherical condenser and a dropping funnel, and the temperature is raised to 90.0°C while stirring and continued to stir at 90°C for 1 hour to obtain a polyvinyl alcohol solution, and the temperature is maintained at 80.0°C; 1 part of the substance is added to a beaker. The method comprises the following steps: adding zirconium oxychloride (ZrOCl2·8H2O) in an amount of 190 parts by weight of distilled water and stirring until dissolved to obtain a zirconium oxychloride solution; adding the zirconium oxychloride solution dropwise to a polyvinyl alcohol solution, and keeping the temperature at 80.0°C for 8 hours, and discharging the material; placing the obtained product in a ventilated drying oven and keeping the temperatures at 70°C and 120°C for 5 hours respectively to obtain a zirconium carbide ceramic precursor; of course, other preparation methods can also be used to synthesize the zirconium carbide ceramic precursor, or the product can be directly purchased from the market;

[0035] (4) subjecting the first densified composite material to a high-temperature treatment, and then subjecting the first densified composite material after the high-temperature treatment to a second densification through a PIP process of impregnation / curing / cracking using a polyborosilazane ceramic precursor solution as an impregnation liquid to obtain a second densified composite material; in the present invention, the high-temperature treatment (high-temperature carbonization treatment) in step (4) can ensure that all the cracking products of the precursor are converted into carbides (SiC, ZrC); in the present invention, the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane and boron powder are uniformly mixed with a solvent such as chloroform and / or xylene to obtain a polyborosilazane ceramic precursor solution, wherein the polyborosilazane ceramic precursor solution contains 30 to 40% by mass of polysilazane and 10 to 30% by mass of boron powder;

[0036] (5) Alternately depositing a silicon carbide coating and a boron nitride nanosheet coating on the surface of the second densified composite material by chemical vapor deposition until a preset thickness or a preset number of layers are reached, thereby obtaining a wide temperature range reusable high thermal conductivity composite material; in the present invention, the silicon carbide coating and the boron nitride nanosheet coating are alternately deposited to form an antioxidant alternating ceramic coating; in step (5), the boron nitride nanosheet coating is deposited in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia, wherein the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is (18 to 20 ): (1-2): (1-2): (1-1.5), the deposition temperature is 900-1100°C (for example, 900°C, 950°C, 1000°C, 1050°C or 1100°C); the present invention finds that a boron nitride nanosheet structure can be obtained by increasing the deposition temperature and regulating the ratio of raw materials; in the present invention, except for the different deposition time, the other process conditions for depositing the boron nitride nanosheet interface layer and the boron nitride nanosheet coating are the same, and by adjusting the deposition time, boron nitride nanosheet interface layers and boron nitride nanosheet coatings of different thicknesses can be obtained.

[0037] The present invention combines high thermal conductivity carbon fiber, wide temperature range anti-oxidation interface layer and multi-component wide temperature range anti-oxidation ceramic matrix to achieve reusability of the material at 700℃~1500℃; the multi-layer alternating anti-oxidation alternating interface layer and anti-oxidation alternating ceramic coating not only have wide temperature range anti-oxidation properties, even if the outermost layer fails due to oxidation, the inner layer can still play a role in protecting the fiber, and has a long repeatable life and high reliability; in the present invention, the process of preparing boron nitride by chemical vapor deposition is adjusted so that the anti-oxidation alternating interface layer is alternately formed by silicon carbide interface layer and boron nitride nanosheet interface layer, and the anti-oxidation alternating ceramic coating is alternately formed by silicon carbide coating and boron nitride nanosheet coating. The present invention finds that the combination of boron nitride nanosheets and silicon carbide can significantly improve the thermal conductivity of the interface layer and coating, which will help to conduct heat more effectively and improve the composite material. The overall thermal conductivity of the material makes it more suitable for applications requiring high thermal conductivity. In the antioxidant alternating interface layer and the antioxidant alternating ceramic coating of the present invention, the formation of the boron nitride nanosheet interface layer and the boron nitride nanosheet coating can significantly improve the thermal conductivity, antioxidant performance and wide temperature range reusability of the material compared to the ordinary boron nitride interface layer and boron nitride coating, making it more suitable for applications in high temperature environments. This interface layer structure and coating structure can provide better thermal conduction and antioxidant performance, which helps the material to exhibit better stability under extreme conditions. The antioxidant alternating interface layer and the antioxidant alternating ceramic coating in the present invention can better protect the carbon fiber from high-temperature oxidation or oxidation in the atmosphere, which helps to extend the service life of the composite material. The high thermal conductivity composite material prepared by the present invention can be reused in a wider temperature range.

[0038] The present invention adopts chemical vapor deposition to prepare an antioxidant alternating interface layer on the fiber surface of a high thermal conductivity carbon fiber preform and an antioxidant alternating ceramic coating on the surface of a composite material. The components and structures of the interface layer and the ceramic coating are similar, and the thermal expansion coefficients are similar. The thermal stress generated during high-low temperature use is small, and cracking is not easy to occur, which is conducive to ensuring the high-temperature mechanical properties of the material. The present invention effectively solves the problems existing in the prior art such as low thermal conductivity, insufficient density, easy oxidation failure of the pyrolytic carbon interface layer or other interface layers, and inability to meet reusability.

[0039] According to some preferred embodiments, in step (1): high thermal conductivity carbon fiber (mesophase pitch-based carbon fiber) and polyacrylonitrile-based carbon fiber are mixed and woven into a carbon fiber preform, and then graphitized to obtain a high thermal conductivity carbon fiber preform; the present invention does not specifically limit the sources of the mesophase pitch-based carbon fiber and the polyacrylonitrile-based carbon fiber, and products that can be directly purchased on the market or products synthesized by existing methods can be used.

[0040] According to some preferred embodiments, high thermal conductivity carbon fiber is woven into a carbon fiber preform, which is then graphitized to obtain a high thermal conductivity carbon fiber preform; for example, the present invention can adopt a 2.5D weaving method of high thermal conductivity carbon fiber (intermediate phase pitch-based carbon fiber), and the fibers are woven at a certain angle in the thickness direction, which has better integrity and avoids the shortcomings of poor interlayer performance of 2D woven composite materials and complex process of 3D woven composite materials.

[0041] According to some preferred embodiments, the volume fraction of carbon fibers in the high thermal conductivity carbon fiber preform is 30-40%, and the density of the high thermal conductivity carbon fiber preform is 0.6-0.9 g / cm 3 ; Preferably, the temperature of the graphitization treatment is 2800-3200°C and the time is 0.5-1h.

[0042] According to some preferred embodiments, in step (1), the preparation of the high thermal conductivity carbon fiber preform includes the following sub-steps:

[0043] (a) The mesophase pitch-based carbon fiber bundles are dispersed by mechanical vibration and / or ultrasonic vibration, and then fixed with hot melt wires to obtain unidirectional asphalt-based carbon fiber cloth; specifically, the mesophase pitch-based carbon fiber bundles are dispersed into a planar structure by mechanical vibration and / or ultrasonic vibration, so that the mesophase pitch-based carbon fiber bundles extend in the width direction and become thinner in the thickness direction, and are fixed with hot melt wires, for example, they can be fixed by suturing with hot melt wires to obtain a unidirectional asphalt-based carbon fiber cloth with a low surface density; more specifically, the mesophase pitch-based carbon fiber bundles are dispersed by mechanical vibration and / or ultrasonic vibration using a transmission device (such as a vibration transmission device) to form a mesophase pitch-based carbon fiber cloth with a planar structure, and the mesophase pitch-based carbon fiber cloth is directly sewed together with linear hot melt wires, for example, the four sides of the mesophase pitch-based carbon fiber cloth are sewed together with hot melt wires, which can play a preliminary fixing role. The thermal fuse has a low residual carbon rate, and in the subsequent process of preparing a high thermal conductivity composite material, it basically disappears after being subjected to high temperature. The spacing of the stitching can be, for example, 1 to 2.5 mm (for example, 1.0, 1.5, 2.0 or 2.5 mm); the present invention does not specifically limit the type of the thermal fuse, and any product that can be directly purchased on the market can be used. In some specific embodiments, the thermal fuse can be, for example, a nylon thermal fuse; the present invention does not specifically limit the conditions of mechanical vibration and ultrasonic vibration, as long as the mesophase pitch-based carbon fiber bundle can be dispersed into a planar structure through mechanical vibration and / or ultrasonic vibration. In the present invention, the frequency of the mechanical vibration can be, for example, 25 to 200 Hz, and the time of the mechanical vibration can be, for example, 1 to 5 minutes; the frequency of the ultrasonic vibration can be, for example, 20 to 40 kHz, and the time of the ultrasonic vibration can be, for example, 1 to 5 minutes;

[0044] (b) After laminating unidirectional asphalt-based carbon fiber cloth, polyacrylonitrile-based carbon fiber is used to sew them together to obtain a high thermal conductivity carbon fiber preform; it should be noted that the unidirectional asphalt-based carbon fiber cloth, "unidirectional" here means that in the same piece (same layer) of asphalt-based carbon fiber cloth, the carbon fibers are arranged in one direction; specifically, after laminating the unidirectional asphalt-based carbon fiber cloth, it is placed in a fixed mold for weaving, and polyacrylonitrile-based carbon fiber is used to sew them in the direction perpendicular to the lamination direction (Z direction) to obtain a high thermal conductivity carbon fiber preform; when laminating, the angle between the fibers in each layer of fiber cloth (two adjacent layers of fiber cloth) is 0° or 90°. °, when the angle is 90°, the ratio of the fiber content in the two directions is, for example, (1 to 4): 1, that is, when the angle is 90°, the fiber volume fraction ratio in the two directions is (1 to 4): 1; in the present invention, when stacking, the unidirectional asphalt-based carbon fiber cloth can be stacked in one direction or alternately stacked vertically in two directions. Vertical stacking in two directions means that the directions of the carbon fibers in two adjacent layers of unidirectional asphalt-based carbon fiber cloth are perpendicular to each other, so that the heat-conducting composite material can be arranged with intermediate phase asphalt-based carbon fibers as heat conductors and reinforcements in one direction (X) or two perpendicular directions (X, Y) within the plane.

[0045] The present invention preferably obtains the high thermal conductivity carbon fiber preform through steps (a) and (b), so that the method of the present invention can be formed to near net size to prepare a large-area dispersed wide temperature range reusable high thermal conductivity composite material, the fiber ratio and matrix composition can be controlled, and the high thermal conductivity composite material prepared using the high thermal conductivity carbon fiber preform has lower density, thinner thickness, higher specific strength, more uniform and dense internal structure, rapid thermal conductivity over a large area in the plane, and better mechanical properties and thermal conductivity.

[0046] The method of the present invention uses a method of dispersing the mesophase asphalt-based carbon fiber bundles by mechanical and / or ultrasonic vibration and then fixing them with hot melt wires to obtain a unidirectional asphalt-based carbon fiber cloth with the characteristic of ultra-thin thickness. The use of this unidirectional asphalt-based carbon fiber cloth can make the prepared high thermal conductivity composite material have a thinner thickness under basically the same density conditions. In the prior art, the mesophase asphalt-based carbon fiber is placed in an organic carbon solution (mesophase asphalt) for impregnation, and then placed in parallel in a mold, and then dried at low temperature to obtain a unidirectional carbon fiber sheet. This method causes the carbon fiber to saturate and absorb the solution during the impregnation process, and the subsequent drying process leaves a layer of asphalt-based material between the fibers, increasing the thickness of the sheet. In the process of placing them in parallel in the mold to obtain a unidirectional structure (unidirectional sheet), stacking of carbon fiber layers is involved, which also increases the thickness of the final sheet. In addition, the present invention found that the unidirectional asphalt-based carbon fiber cloth obtained by the present invention through mechanical and / or ultrasonic vibration dispersion and then fixing with hot melt wire can obtain a more consistent and uniform carbon fiber arrangement, and the directionality of the carbon fibers is more uniform. This consistency helps to improve the high thermal conductivity composite material. The strength and stability of the composite material are improved, which helps to resist bending stress. The thinner unidirectional asphalt-based carbon fiber cloth obtained by the present invention means that the overall performance of the material is better and more uniform. For example, for the preparation of a heat-conducting composite material with a total thickness of 3mm, a thicker carbon cloth is used and the number of stacked layers is small. For example, a carbon cloth with a common thickness of 0.5-1mm can only be stacked 3-6 layers. The thickness of the dispersed unidirectional asphalt-based carbon fiber cloth in the present invention can be as thin as 0.1-0.2mm, and the unidirectional asphalt-based carbon fiber cloth can be stacked 15-30 layers. The number of layers is relatively large, and the layers are relatively close. The spacing is smaller, and the obtained thermal conductivity composite material has better uniformity in the thickness direction, the overall performance difference of the material is small, the performance is more uniform, and the material stability is better, especially the stability is better when used for a long time. Taking the high thermal conductivity composite material formed by 6 layers of carbon cloth with a thickness of 0.5mm as an example, if it peels off during use, the material loss rate will reach 16.67% if one layer is peeled off. For the thermal conductivity composite material formed by 20 layers of unidirectional asphalt-based carbon fiber cloth with a thickness of 0.15mm, even if one layer is peeled off, the material loss rate is only 5%.

[0047] According to some preferred embodiments, the diameter of the mesophase pitch-based carbon fibers (high thermal conductivity carbon fibers) in the mesophase pitch-based carbon fiber bundle is 10 to 11 μm, the thermal conductivity after graphitization treatment is not less than 850 W / (m·K), the tensile strength is greater than 2.4 GPa, the tensile modulus is greater than 950 GPa, and / or the specification of the mesophase pitch-based carbon fiber bundle is 1K to 4K (for example, 1K, 2K, 3K or 4K); the high thermal conductivity carbon fibers account for 60 to 100% of the volume fraction of the carbon fibers in the high thermal conductivity carbon fiber preform, and the volume density of the high thermal conductivity carbon fiber preform is 0.6 to 1.1 g / cm 3 , preferably 0.6 to 0.9 g / cm 3 .

[0048] According to some preferred embodiments, the width of the dispersed mesophase pitch-based carbon fiber bundle is 15 to 20 mm (e.g., 15, 16, 17, 18, 19 or 20 mm); the surface density of the unidirectional pitch-based carbon fiber cloth is 50 to 100 g / m 2 (e.g. 50, 60, 70, 80, 90 or 100 g / m 2 ), with a thickness of 0.1 to 0.2 mm (for example, 0.1, 0.15 or 0.2 mm).

[0049] According to some preferred embodiments, in step (b): the unidirectional asphalt-based carbon fiber cloth is laminated in one direction or in two directions; the angle between the fibers in each layer of unidirectional asphalt-based carbon fiber cloth is 0° or 90°, that is, the angle between the fibers in two adjacent layers of unidirectional asphalt-based carbon fiber cloth is 0° or 90°; in the present invention, when the unidirectional asphalt-based carbon fiber cloth is laminated in one direction, a unidirectional high thermal conductivity carbon fiber preform is formed, and the carbon fibers in each layer of unidirectional asphalt-based carbon fiber cloth are arranged in one direction, and the angle between the carbon fibers is 0°; when the unidirectional asphalt-based carbon fiber cloth is laminated in two directions, the angle between the fibers is 0°. When the layers are alternately stacked in two directions, a bidirectional vertical high thermal conductivity carbon fiber preform is formed. The carbon fibers in the asphalt-based carbon fiber cloth are arranged in two directions, and the angle between the carbon fibers in two adjacent layers of unidirectional asphalt-based carbon fiber cloth is 90°; when the angle between the fibers is 90°, the ratio of the fiber content in the two directions (fiber volume fraction) is (1 to 4): 1 (for example, 1:1, 2:1, 3:1 or 4:1); polyacrylonitrile-based carbon fibers are used for stitching perpendicular to the stacking direction, and the stitching spacing is 1 to 2.5 mm (for example, 1.0, 1.5, 2.0 or 2.5 mm).

[0050] According to some preferred embodiments, in step (2): the number of layers of the silicon carbide interface layer and the boron nitride nanosheet interface layer are both n layers, n is 2 to 4 (for example, 2, 3 or 4) and n is a natural number; when depositing the silicon carbide interface layer, the deposition temperature is 1000 to 1100°C, the thickness of the single-layer silicon carbide interface layer is 0.1 to 0.2 μm; the thickness of the single-layer boron nitride nanosheet interface layer is 0.1 to 0.2 μm; preferably, the thickness ratio of the single-layer silicon carbide interface layer to the single-layer boron nitride nanosheet interface layer is (0.8 to 1.2):1.

[0051] The present invention does not impose any specific limitation on the deposition time of the single-layer silicon carbide interface layer and the single-layer boron nitride nanosheet interface layer. Those skilled in the art can adjust the deposition time until the preset thickness is reached. In the present invention, when chemical vapor deposition is performed, the deposition pressure is, for example, 5 to 10 kPa, unless otherwise specified. The present invention does not impose any specific limitation on the PIP process conditions of impregnation / curing / cracking in steps (3) and (4), which are conventional techniques in the art.

[0052] According to some preferred embodiments, in step (3): first, a polycarbosilane ceramic precursor solution is used as an impregnation liquid to perform 3 to 5 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 900 to 1200°C, and the time for each cracking is 2 to 4 hours, and then a zirconium-based ceramic precursor solution is used as an impregnation liquid to perform 5 to 10 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 1400 to 1500°C, and the time for each cracking is 2 to 4 hours.

[0053] According to some preferred embodiments, in step (4): the temperature of the high temperature treatment is 1600°C to 2000°C, the time is 3 to 5 hours, and / or the high temperature treatment is carried out under an inert atmosphere; and / or a polyborosilazane ceramic precursor solution is used as an impregnation liquid to carry out 8 to 15 rounds of impregnation / curing / cracking PIP process until the weight gain of the composite material after the last cracking is less than 0.5%; the cracking temperature is 1000 to 1300°C, and the time of each cracking is 2 to 4 hours.

[0054] According to some preferred embodiments, in step (5): the number of layers of the silicon carbide coating and the boron nitride nanosheet coating is m, m is 2 to 4 (for example, 2, 3 or 4) and m is a natural number; when depositing the silicon carbide coating, the deposition temperature is 1000 to 1100°C, the thickness of the single-layer silicon carbide coating is 15 to 20 μm; the thickness of the single-layer boron nitride nanosheet coating is 15 to 20 μm; preferably, the thickness ratio of the single-layer silicon carbide coating to the single-layer boron nitride nanosheet coating is (0.8 to 1.2): 1; preferably, the silicon carbide coating and the boron nitride nanosheet coating are alternately deposited to form an antioxidant alternating ceramic coating, and the total thickness of the antioxidant alternating ceramic coating is 60 to 160 μm, preferably 80 to 120 μm.

[0055] According to some preferred embodiments, the polycarbosilane ceramic precursor solution, the zirconium-based ceramic precursor solution and the polyborosilazane ceramic precursor solution all contain boron nitride nanosheets (BN nanosheets); the mass fraction of the boron nitride nanosheets in the polycarbosilane ceramic precursor solution is 2-3% (e.g., 2%, 2.5% or 3%); the mass fraction of the boron nitride nanosheets in the zirconium-based ceramic precursor solution is 4-6% (e.g., 4%, 4.5%, 5%, 5.5% or 6%); the mass fraction of the boron nitride nanosheets in the polyborosilazane ceramic precursor solution is 2-3% (e.g., 2%, 2.5% or 3%); in the present invention, when the ceramic precursor solution contains boron nitride nanosheets, the boron nitride nanosheets are concentrated in the solution. When preparing the boron nitride nanosheets, the ceramic precursor solution is prepared as follows: the ceramic precursor and the boron nitride nanosheets are added to the solvent, and then stirred and ultrasonically treated to obtain the obtained product; in the present invention, the stirring speed is, for example, 400 to 800 rpm, and the stirring time is, for example, 20 to 40 minutes; the frequency of the ultrasonic treatment is 20 to 40 kHz, and the ultrasonic treatment time is, for example, 20 to 40 minutes; in the present invention, the ceramic precursor and the boron nitride nanosheets are evenly dispersed in the solvent by stirring and ultrasonic treatment, and the boron nitride nanosheets are evenly distributed in the entire ceramic precursor solution as much as possible, thereby facilitating the improvement of the uniformity of the wide temperature range reusable high thermal conductivity composite material and helping to ensure the performance of the material.

[0056] The present invention preferably contains an appropriate amount of boron nitride nanosheets in the polycarbosilane ceramic precursor solution, the zirconium-based ceramic precursor solution, and the polyborosilazane ceramic precursor solution during the impregnation / curing / cracking PIP process, which is beneficial to improving the high thermal conductivity and oxidation resistance of the material, and helps to improve the wide temperature range reusability of the material. In addition, the present invention uses different ceramic precursors for densification and controls the content of boron nitride nanosheets in each ceramic precursor, which can effectively adjust the thermal matching and high-temperature mechanical properties of the composite material, which helps to reduce the thermal stress and deformation problems of the material under high temperature conditions, improves the thermal stability and thermal expansion matching of the material in a high temperature environment, and also helps to improve the wide temperature range reusability of the material.

[0057] According to some preferred embodiments, the boron nitride nanosheets have a sheet diameter of 1 to 2 μm and a thickness of 60 to 120 nm.

[0058] In a third aspect, the present invention provides a high thermal conductivity composite material that is reusable over a wide temperature range and is prepared by the preparation method described in the second aspect of the present invention.

[0059] The present invention will be further described below with reference to the following examples. These examples are merely illustrative of preferred embodiments of the present invention, and the scope of protection of the present invention should not be construed as being limited to these examples.

[0060] Example 1

[0061] ① A 2.5D woven structure of 2K mesophase pitch-based carbon fiber (high thermal conductivity mesophase pitch-based carbon fiber) is used. 2K mesophase pitch-based carbon fiber is used in the plane X and Y directions (the angle between the two directions is 90°), and 2K mesophase pitch-based carbon fiber is also used in the thickness direction (Z direction) to interweave the XY surface fiber layers as a whole to form a 2.5D woven structure. After graphitization treatment at 3000℃ for 1h, a high thermal conductivity carbon fiber preform is obtained; the volume fraction of carbon fiber in the high thermal conductivity carbon fiber preform is 35%, and the density of the high thermal conductivity carbon fiber preform is 0.7g / cm 3 .

[0062] ② By chemical vapor deposition, silicon carbide interface layer (SiC interface layer) and boron nitride nanosheet (BN nanosheet) interface layer are alternately deposited on the fiber surface of the high thermal conductivity carbon fiber preform obtained in step ① to obtain an anti-oxidation alternating interface layer (SiC / BN nanosheet) nThe intermediate body is n=3, i.e., the anti-oxidation alternating interface layer is composed of SiC interface layer, BN nanosheet interface layer, SiC interface layer, BN nanosheet interface layer, SiC interface layer and BN nanosheet interface layer in sequence; the thickness of the single-layer SiC interface layer is 0.15 μm, the thickness of the single-layer BN nanosheet interface layer is 0.15 μm, and the total thickness of the anti-oxidation alternating interface layer is 0.9 μm; when depositing the SiC interface layer, it is placed in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon is 0.15 μm). The BN nanosheet interface layer was deposited in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia was 18:1:2:1.5) at 1050°C and 6kPa until the thickness of the single-layer SiC interface layer was 0.15 μm, and then a single-layer BN nanosheet interface layer was deposited. When depositing the BN nanosheet interface layer, the BN nanosheet interface layer was deposited in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia was 18:1:2:1.5) at 1050°C and 6kPa until the thickness of the single-layer BN nanosheet interface layer was 0.15 μm.

[0063] ③ Using polycarbosilane ceramic precursor solution and zirconium-based ceramic precursor solution as impregnation liquids in sequence, the intermediate body obtained in step ② is subjected to a first densification through a PIP process of impregnation / curing / cracking to obtain a first densified composite material; the polycarbosilane ceramic precursor solution is prepared by uniformly mixing polycarbosilane with xylene to obtain a polycarbosilane ceramic precursor solution, wherein the mass percentage of polycarbosilane in the polycarbosilane ceramic precursor solution is 60%; the zirconium-based ceramic precursor solution is prepared by uniformly mixing zirconium carbide ceramic precursor with xylene to obtain a zirconium-based ceramic precursor solution, wherein the mass fraction of zirconium carbide ceramic precursor in the zirconium-based ceramic precursor solution is 60wt%; the PIP process is as follows: first, a polycarbosilane ceramic precursor solution is used as The impregnation liquid was subjected to 4 rounds of impregnation, curing and cracking, the impregnation was carried out at room temperature, the impregnation time was 2 hours, the impregnation pressure was 1.5 MPa, the curing temperature was 250°C, the curing time was 3 hours, the curing pressure was 2 MPa, the cracking temperature was 1000°C, the cracking time was 2 hours each time, and the cracking was carried out in an inert atmosphere (argon); then the zirconium-based ceramic precursor solution was used as the impregnation liquid for 8 rounds of impregnation, curing and cracking, the impregnation was carried out at room temperature, the impregnation time was 2 hours each time, the impregnation pressure was 1.5 MPa, the curing temperature was 280°C, the curing time was 2 hours each time, the curing pressure was 2 MPa, the cracking temperature was 1450°C, the cracking time was 2 hours each time, and the cracking was carried out in an inert atmosphere (argon).

[0064] ④ The first densified composite material obtained in step ③ is subjected to high temperature treatment at 1800 ° C in an argon atmosphere for 3 hours, and then the first densified composite material after high temperature treatment is subjected to a second densification by a PIP process of impregnation / curing / cracking using a polyborosilazane ceramic precursor solution as an impregnation liquid to obtain a second densified composite material; the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane and boron powder are uniformly mixed with chloroform (trichloromethane) to obtain a polyborosilazane ceramic precursor solution, wherein the polyborosilazane ceramic precursor solution contains polysilazane. The mass fraction of azane is 35%, and the mass fraction of boron powder is 20%. The PIP process is as follows: a polyborosilazane ceramic precursor solution is used as an impregnation liquid for 12 rounds of impregnation, curing, and cracking. After the last cracking, the weight gain of the composite material is 0.3%. Vacuum impregnation is carried out at room temperature, and the time for each vacuum impregnation is 50 minutes. The curing temperature is 280°C, the time for each curing is 3 hours, the curing pressure is 2MPa, the cracking temperature is 1100°C, the time for each cracking is 2 hours, and the cracking is carried out in an argon atmosphere.

[0065] ⑤ Alternately depositing a silicon carbide coating and a boron nitride nanosheet coating on the surface of the second densified composite material obtained in step ④ by chemical vapor deposition to prepare a wide temperature range reusable high thermal conductivity composite material, and alternately depositing the silicon carbide coating and the boron nitride nanosheet coating to form an oxidation-resistant alternating ceramic coating (SiC / BN nanosheet) m , m is 3, that is, the oxidation-resistant alternating ceramic coating is composed of SiC coating, BN nanosheet coating, SiC coating, BN nanosheet coating, SiC coating and BN nanosheet coating in sequence; the thickness of the single-layer SiC coating is 20 μm, the thickness of the single-layer BN nanosheet coating is 20 μm, and the total thickness of the oxidation-resistant alternating ceramic coating is 120 μm; when depositing the SiC coating, it is placed in an atmosphere containing trichloromethylsilane, argon and hydrogen (the molar ratio of trichloromethylsilane, hydrogen and argon is 1 :2:10) at 1050°C and 6 kPa for deposition until the thickness of the single-layer SiC coating is 20 μm, and then a single-layer BN nanosheet coating is deposited; when depositing the BN nanosheet coating, it is placed in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is 18:1:2:1.5) and deposited at 1050°C and 6 kPa until the thickness of the single-layer BN nanosheet coating is 20 μm.

[0066] Example 2

[0067] Example 2 is basically the same as Example 1, except that:

[0068] Step ③ is: using a polycarbosilane ceramic precursor solution and a zirconium-based ceramic precursor solution as impregnation liquids in sequence, performing a first densification on the intermediate body obtained in step ② through a PIP process of impregnation / curing / cracking to obtain a first densified composite material; the polycarbosilane ceramic precursor solution is prepared by adding polycarbosilane and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm to xylene, and then stirring and ultrasonically treating to obtain a polycarbosilane ceramic precursor solution, first stirring at a stirring speed of 400 rpm. The polycarbosilane ceramic precursor solution contains 60 wt% of polycarbosilane and 2.5 wt% of boron nitride nanosheets. The zirconium-based ceramic precursor solution is prepared by adding a zirconium carbide ceramic precursor and boron nitride nanosheets having a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm to xylene, and then stirring and ultrasonically treating the zirconium-based ceramic precursor solution. The solution is first stirred at a stirring speed of 400 r / min and then subjected to a stirring process. The mixture was stirred at 100 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The zirconium-based ceramic precursor solution contained 60 wt% of zirconium carbide ceramic precursor and 4.5 wt% of boron nitride nanosheets. The PIP process was as follows: a polycarbosilane ceramic precursor solution was first used as an impregnation liquid for four rounds of impregnation, curing, and cracking. The impregnation was carried out at room temperature for 2 hours each time, the impregnation pressure was 1.5 MPa, the curing temperature was 250° C., and the curing time was 3 hours each time. , the curing pressure is 2MPa, the cracking temperature is 1000℃, the time for each cracking is 2h, and the cracking is carried out in an inert atmosphere (argon); then the zirconium-based ceramic precursor solution is used as the impregnation liquid for 8 rounds of impregnation, curing, and cracking, impregnation at room temperature, the time for each impregnation is 2h, the impregnation pressure is 1.5MPa, the curing temperature is 280℃, the time for each curing is 2h, the curing pressure is 2MPa, the cracking temperature is 1450℃, the time for each cracking is 2h, and the cracking is carried out in an inert atmosphere (argon).

[0069] Step ④ is: subjecting the first densified composite material obtained in step ③ to a high temperature treatment at 1800°C in an argon atmosphere for 3 hours, and then using a polyborosilazane ceramic precursor solution as an impregnation liquid to perform a second densification on the first densified composite material after high temperature treatment through an impregnation / curing / cracking PIP process to obtain a second densified composite material; the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane, boron powder and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to chloroform, and then stirred and ultrasonically treated to obtain a polyborosilazane ceramic precursor solution, first stirred at a stirring speed of 400 rpm for 30 minutes, and then at a frequency of 20 k Hz conditions for ultrasonic treatment for 30 minutes, the polyborosilazane ceramic precursor solution contains a mass fraction of polysilazane of 35%, a mass fraction of boron powder of 20%, and a mass fraction of boron nitride nanosheets of 2.5wt%; the PIP process is as follows: using the polyborosilazane ceramic precursor solution as an impregnation liquid for 12 rounds of impregnation, curing, and cracking, the weight gain of the composite material after the last cracking is 0.3%, vacuum impregnation is carried out at room temperature, the time of each vacuum impregnation is 50 minutes, the curing temperature is 280°C, the time of each curing is 3 hours, the curing pressure is 2MPa, the cracking temperature is 1100°C, the time of each cracking is 2 hours, and the cracking is carried out in an argon atmosphere.

[0070] Example 3

[0071] Example 3 is basically the same as Example 2, except that:

[0072] In step ③, the polycarbosilane ceramic precursor solution is prepared as follows: polycarbosilane and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to xylene, and then stirred and ultrasonically treated to obtain a polycarbosilane ceramic precursor solution, first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The polycarbosilane ceramic precursor solution contains 60 wt% of polycarbosilane and 4.5 wt% of boron nitride nanosheets. %; the zirconium-based ceramic precursor solution is prepared as follows: a zirconium carbide ceramic precursor and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to xylene, and then the zirconium-based ceramic precursor solution is obtained by stirring and ultrasonic treatment. The solution is first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The mass fraction of the zirconium carbide ceramic precursor in the zirconium-based ceramic precursor solution is 60 wt%, and the mass fraction of the boron nitride nanosheets is 4.5 wt%.

[0073] In step ④, the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane, boron powder and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to chloroform, and then stirred and ultrasonically treated to obtain a polyborosilazane ceramic precursor solution, first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The polyborosilazane ceramic precursor solution contains 35% by mass of polysilazane, 20% by mass of boron powder, and 4.5% by mass of boron nitride nanosheets.

[0074] Example 4

[0075] Example 4 is basically the same as Example 2, except that:

[0076] In step ③, the polycarbosilane ceramic precursor solution is prepared as follows: polycarbosilane and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to xylene, and then stirred and ultrasonically treated to obtain a polycarbosilane ceramic precursor solution, first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The polycarbosilane ceramic precursor solution contains 60 wt% of polycarbosilane and 2 wt% of boron nitride nanosheets. %; the zirconium-based ceramic precursor solution is prepared as follows: a zirconium carbide ceramic precursor and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to xylene, and then the zirconium-based ceramic precursor solution is obtained by stirring and ultrasonic treatment. The solution is first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The zirconium-based ceramic precursor solution contains 60 wt% of zirconium carbide ceramic precursor by weight and 3 wt% of boron nitride nanosheets by weight.

[0077] In step ④, the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane, boron powder and boron nitride nanosheets with a sheet diameter distribution range of 1 to 2 μm and a thickness distribution range of 60 to 120 nm are added to chloroform, and then stirred and ultrasonically treated to obtain a polyborosilazane ceramic precursor solution, first stirred at a stirring speed of 400 rpm for 30 minutes, and then ultrasonically treated at a frequency of 20 kHz for 30 minutes. The polyborosilazane ceramic precursor solution contains 35% by mass of polysilazane, 20% by mass of boron powder, and 4.5% by mass of boron nitride nanosheets.

[0078] Example 5

[0079] Example 5 is basically the same as Example 1, except that:

[0080] ① The mesophase pitch-based carbon fiber bundle is dispersed into a planar structure by mechanical vibration and fixed with hot melt stitching with a stitching spacing of 1.5 mm to obtain a unidirectional asphalt-based carbon fiber cloth; the frequency of the mechanical vibration is 100 Hz, and the time of the mechanical vibration is 3 min; the fiber diameter of the mesophase pitch-based carbon fiber bundle used is 10.5±0.2 μm, the thermal conductivity after graphitization treatment is 860 W / (m·K), the fiber bundle specification is 2K, the tensile strength is 2.5 GPa, the tensile modulus is 960 GPa, the width of the dispersed mesophase pitch-based carbon fiber bundle is 20 mm, and the surface density of the prepared unidirectional asphalt-based carbon fiber cloth is 80 g / m 2 The thickness of a single-layer unidirectional asphalt-based carbon fiber cloth is 0.15 mm; 10 layers of unidirectional asphalt-based carbon fiber cloth are alternately stacked in two directions (alternately stacked in two directions of 0° / 90°) and placed in a fixed mold for weaving. Polyacrylonitrile-based carbon fibers are used for stitching in the vertical direction (Z) to obtain a high thermal conductivity carbon fiber preform with a thickness of 1.5 mm; the high thermal conductivity carbon fiber preform is a bidirectional vertical high thermal conductivity carbon fiber preform, the angle between the fibers in the two adjacent layers of unidirectional asphalt-based carbon fiber cloth is 90°, the ratio of the fiber content in the two directions (fiber volume fraction ratio) is 1:1, the spacing between the fibers in the Z direction (stitching spacing) is 1.5 mm, and the density of the high thermal conductivity carbon fiber preform is 0.9 g / cm 3 .

[0081] Example 6

[0082] Example 6 is basically the same as Example 2, except that:

[0083] ① The mesophase pitch-based carbon fiber bundle is dispersed into a planar structure by mechanical vibration and fixed with hot melt stitching with a stitching spacing of 1.5 mm to obtain a unidirectional asphalt-based carbon fiber cloth; the frequency of the mechanical vibration is 100 Hz, and the time of the mechanical vibration is 3 min; the fiber diameter of the mesophase pitch-based carbon fiber bundle used is 10.5±0.2 μm, the thermal conductivity after graphitization treatment is 860 W / (m·K), the fiber bundle specification is 2K, the tensile strength is 2.5 GPa, the tensile modulus is 960 GPa, the width of the dispersed mesophase pitch-based carbon fiber bundle is 20 mm, and the surface density of the prepared unidirectional asphalt-based carbon fiber cloth is 80 g / m 2The thickness of a single-layer unidirectional asphalt-based carbon fiber cloth is 0.15 mm; 10 layers of unidirectional asphalt-based carbon fiber cloth are alternately stacked in two directions (alternately stacked in two directions of 0° / 90°) and placed in a fixed mold for weaving. Polyacrylonitrile-based carbon fibers are used for stitching in the vertical direction (Z) to obtain a high thermal conductivity carbon fiber preform with a thickness of 1.5 mm; the high thermal conductivity carbon fiber preform is a bidirectional vertical high thermal conductivity carbon fiber preform, the angle between the fibers in the two adjacent layers of unidirectional asphalt-based carbon fiber cloth is 90°, the ratio of the fiber content in the two directions (fiber volume fraction ratio) is 1:1, the spacing between the fibers in the Z direction (stitching spacing) is 1.5 mm, and the density of the high thermal conductivity carbon fiber preform is 0.9 g / cm 3 .

[0084] Comparative Example 1

[0085] Comparative Example 1 is substantially the same as Example 1, except that:

[0086] ② By chemical vapor deposition, silicon carbide interface layer (SiC interface layer) and ordinary boron nitride (BN) interface layer are alternately deposited on the fiber surface of the high thermal conductivity carbon fiber preform obtained in step ① to obtain an anti-oxidation alternating interface layer (SiC / ordinary BN) n The intermediate body is n=3, that is, the anti-oxidation alternating interface layer is composed of SiC interface layer, BN interface layer, SiC interface layer, BN interface layer, SiC interface layer and BN interface layer in sequence; the thickness of the single-layer SiC interface layer is 0.15 μm, the thickness of the single-layer BN interface layer is 0.15 μm, and the total thickness of the anti-oxidation alternating interface layer is 0.9 μm; when depositing the SiC interface layer, it is placed in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon is 0.15 μm). The SiC interface layer was deposited at 1050°C and 6 kPa in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia was 10:1.5:1:3) until the thickness of the single-layer BN interface layer was 0.15 μm.

[0087] ⑤ Alternately depositing a silicon carbide coating and a boron nitride coating on the surface of the second densified composite material obtained in step ④ by chemical vapor deposition to obtain a wide temperature range reusable high thermal conductivity composite material, and alternately depositing a silicon carbide coating and a conventional boron nitride coating (conventional BN coating) to form an oxidation-resistant alternating ceramic coating (SiC / conventional BN) m, m is 3, that is, the oxidation-resistant alternating ceramic coating is composed of a SiC coating, a BN coating, a SiC coating, a BN coating, a SiC coating and a BN coating in sequence; the thickness of the single-layer SiC coating is 20 μm, the thickness of the single-layer BN coating is 20 μm, and the total thickness of the oxidation-resistant alternating ceramic coating is 120 μm; when depositing the SiC coating, it is placed in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon is 1:2:10) and deposited at 1050° C. and 6 kPa until the thickness of the single-layer SiC coating is 20 μm, and then a single-layer BN coating is deposited; when depositing the BN coating, it is placed in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is 10:1.5:1:3) and deposited at 680° C. and 6 kPa until the thickness of the single-layer BN coating is 20 μm.

[0088] Comparative Example 2

[0089] Comparative Example 2 is substantially the same as Comparative Example 1, except that:

[0090] ② By chemical vapor deposition, a conventional boron nitride (BN) interface layer and a silicon carbide interface layer (SiC interface layer) are alternately deposited on the fiber surface of the high thermal conductivity carbon fiber preform obtained in step ① to obtain an anti-oxidation alternating interface layer (conventional BN / SiC) n The intermediate body is n=3, that is, the anti-oxidation alternating interface layer is composed of BN interface layer, SiC interface layer, BN interface layer, SiC interface layer, BN interface layer and SiC interface layer in sequence; the thickness of the single-layer BN interface layer is 0.15 μm, the thickness of the single-layer SiC interface layer is 0.15 μm, and the total thickness of the anti-oxidation alternating interface layer is 0.9 μm; when depositing the BN interface layer, it is placed in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (nitrogen, hydrogen, boron trichloride gas and The SiC interface layer was deposited in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon was 1:2:10) at 1050°C and 6kPa until the thickness of the single-layer SiC interface layer was 0.15 μm.

[0091] ⑤ By chemical vapor deposition, a conventional boron nitride coating and a silicon carbide coating are alternately deposited on the surface of the second densified composite material obtained in step ④ to prepare a wide temperature range reusable high thermal conductivity composite material, and an anti-oxidation alternating ceramic coating (conventional BN coating) and a silicon carbide coating are alternately deposited. m, m is 3, that is, the oxidation-resistant alternating ceramic coating is composed of a BN coating, a SiC coating, a BN coating, a SiC coating, a BN coating and a SiC coating in sequence; the thickness of the single-layer BN coating is 20 μm, the thickness of the single-layer SiC coating is 20 μm, and the total thickness of the oxidation-resistant alternating ceramic coating is 120 μm; when depositing the BN coating, it is placed in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is 10:1.5:1:3) at 680°C and 6 kPa for deposition until the thickness of the single-layer BN coating is 20 μm, and then the SiC coating is deposited; when depositing the SiC coating, it is placed in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon is 1:2:10) at 1050°C and 6 kPa for deposition until the thickness of the single-layer SiC coating is 20 μm.

[0092] Comparative Example 3

[0093] Comparative Example 3 is substantially the same as Example 1, except that:

[0094] ② The high thermal conductivity carbon fiber preform obtained in step ① is placed in an atmosphere containing argon and methane gas, and a pyrolytic carbon interface layer (carbon interface layer) is deposited on the fiber surface of the high thermal conductivity carbon fiber preform by chemical vapor deposition at 1050°C and 6kPa. The thickness of the pyrolytic carbon interface layer is 0.9μm, and an intermediate blank containing a pyrolytic carbon interface layer is obtained; the intermediate blank is used to perform subsequent steps; wherein, the volume flow rate ratio of argon and methane gas is 1:1.

[0095] Comparative Example 4

[0096] ① is the same as step ① in Example 1.

[0097] ② Using polycarbosilane ceramic precursor solution and zirconium-based ceramic precursor solution as impregnation liquids in sequence, the high thermal conductivity carbon fiber preform obtained in step ① is subjected to a first densification through a PIP process of impregnation / curing / cracking to obtain a first densified composite material; the polycarbosilane ceramic precursor solution is prepared by uniformly mixing polycarbosilane with xylene to obtain a polycarbosilane ceramic precursor solution, wherein the mass percentage of polycarbosilane in the polycarbosilane ceramic precursor solution is 60%; the zirconium-based ceramic precursor solution is prepared by uniformly mixing zirconium carbide ceramic precursor with xylene to obtain a zirconium-based ceramic precursor solution, wherein the mass fraction of zirconium carbide ceramic precursor in the zirconium-based ceramic precursor solution is 60wt%; the PIP process is as follows: first, a polycarbosilane ceramic precursor solution is prepared by uniformly mixing a zirconium carbide ceramic precursor with xylene to obtain a zirconium-based ceramic precursor solution, wherein the mass fraction of zirconium carbide ceramic precursor in the zirconium-based ceramic precursor solution is 60wt%; The invention relates to an embodiment of the present invention wherein the zirconium-based ceramic precursor solution is used as the impregnation liquid for 4 rounds of impregnation, curing and cracking, the impregnation is carried out at room temperature, the impregnation time is 2h, the impregnation pressure is 1.5MPa, the curing temperature is 250℃, the curing time is 3h, the curing pressure is 2MPa, the cracking temperature is 1000℃, the cracking time is 2h each time, and the cracking is carried out in an inert atmosphere (argon); then the zirconium-based ceramic precursor solution is used as the impregnation liquid for 8 rounds of impregnation, curing and cracking, the impregnation is carried out at room temperature, the impregnation time is 2h each time, the impregnation pressure is 1.5MPa, the curing temperature is 280℃, the curing time is 2h each time, the curing pressure is 2MPa, the cracking temperature is 1450℃, the cracking time is 2h each time, and the cracking is carried out in an inert atmosphere (argon).

[0098] ③ The first densified composite material obtained in step ② is subjected to high temperature treatment at 1800 ° C in an argon atmosphere for 3 hours, and then the first densified composite material after high temperature treatment is subjected to a second densification by a PIP process of impregnation / curing / cracking using a polyborosilazane ceramic precursor solution as an impregnation liquid to obtain a second densified composite material; the polyborosilazane ceramic precursor solution is prepared as follows: polysilazane and boron powder are uniformly mixed with chloroform (trichloromethane) to obtain a polyborosilazane ceramic precursor solution, wherein the polyborosilazane ceramic precursor solution contains polysilazane. The mass fraction of azane is 35%, and the mass fraction of boron powder is 20%. The PIP process is as follows: a polyborosilazane ceramic precursor solution is used as an impregnation liquid for 12 rounds of impregnation, curing, and cracking. After the last cracking, the weight gain of the composite material is 0.3%. Vacuum impregnation is carried out at room temperature, and the time for each vacuum impregnation is 50 minutes. The curing temperature is 280°C, the time for each curing is 3 hours, the curing pressure is 2MPa, the cracking temperature is 1100°C, the time for each cracking is 2 hours, and the cracking is carried out in an argon atmosphere.

[0099] ④ Alternately depositing a silicon carbide coating and a boron nitride nanosheet coating on the surface of the second densified composite material obtained in step ③ by chemical vapor deposition to prepare a wide temperature range reusable high thermal conductivity composite material, and alternately depositing the silicon carbide coating and the boron nitride nanosheet coating to form an oxidation-resistant alternating ceramic coating (SiC / BN nanosheet) m , m is 3, that is, the oxidation-resistant alternating ceramic coating is composed of SiC coating, BN nanosheet coating, SiC coating, BN nanosheet coating, SiC coating and BN nanosheet coating in sequence; the thickness of the single-layer SiC coating is 20 μm, the thickness of the single-layer BN nanosheet coating is 20 μm, and the total thickness of the oxidation-resistant alternating ceramic coating is 120 μm; when depositing the SiC coating, it is placed in an atmosphere containing trichloromethylsilane, hydrogen and argon (the molar ratio of trichloromethylsilane, hydrogen and argon is 1 :2:10) at 1050°C and 6 kPa for deposition until the thickness of the single-layer SiC coating is 20 μm, and then a single-layer BN nanosheet coating is deposited; when depositing the BN nanosheet coating, it is placed in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia (the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is 18:1:2:1.5) and deposited at 1050°C and 6 kPa until the thickness of the single-layer BN nanosheet coating is 20 μm.

[0100] Comparative Example 5

[0101] Comparative Example 5 is substantially the same as Example 1, except that:

[0102] After the second densified composite material is obtained in step ④, step ⑤ is not performed.

[0103] Comparative Example 6

[0104] With reference to Example 2 of Chinese patent application CN202111320084.3, a mullite fiber reinforced ceramic matrix composite material is provided.

[0105] The present invention conducted performance tests on the wide temperature range reusable high thermal conductivity composite materials prepared in each embodiment and the composite materials finally prepared in each comparative example. The test results are shown in Table 1.

[0106] Table 1

[0107]

[0108] In Table 1, the symbol “-” indicates that the performance index has not been tested; it is particularly noted that in Table 1, the longer the 700°C, 90MPa cyclic stress oxidation life (single insulation 1h) and 1500°C, 90MPa cyclic stress oxidation life (single insulation 1h) are, the longer the material can be reused and has a longer reusable service life in a wide temperature range of 700-1500°C; the present invention takes the test of “1500°C, 90MPa cyclic stress oxidation life” as an example for explanation, and “1500°C, 90MPa cyclic stress oxidation life” means that the material is heated to To 1500℃, and give the material a tensile force of 90MPa, keep it warm at 1500℃ and 90MPa in air atmosphere for 1h, then cool the material to room temperature, this is a test cycle, and the cyclic stress oxidation life of the material is recorded as 1h, then heat the material to 1500℃ again, and give the material a tensile force of 90MPa, keep it warm at 1500℃ and 90MPa in air atmosphere for another 1h, then cool the material to room temperature, this is the next test cycle; the material is subjected to 1500℃, 90MPa cyclic stress oxidation life test in this cycle until the material is broken.

[0109] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A reusable high thermal conductivity composite material with a wide temperature range, characterized by: The preform used in the wide temperature range reusable high thermal conductivity composite material is a high thermal conductivity carbon fiber preform, and the fiber surface of the preform has an anti-oxidation alternating interface layer, which is formed by alternating n layers of silicon carbide interface layers and n layers of boron nitride nanosheet interface layers; The wide temperature range reusable high thermal conductivity composite material has a wide temperature range anti-oxidation ceramic matrix, and the wide temperature range anti-oxidation ceramic matrix comprises a SiC matrix, a ZrC matrix and a SiCBN matrix; The wide-temperature-range reusable high-thermal-conductivity composite material has an anti-oxidation alternating ceramic coating, which is formed by alternating m layers of silicon carbide coatings and m layers of boron nitride nanosheet coatings.

2. The wide temperature range reusable high thermal conductivity composite material according to claim 1, characterized in that: The density of the wide temperature range reusable high thermal conductivity composite material is 2.4-3.2 g / cm 3 and / or The wide-temperature-range reusable high-thermal-conductivity composite material has the characteristics of wide-temperature-range reusability and high thermal conductivity.

3. A method for preparing a wide temperature range reusable high thermal conductivity composite material, characterized in that: The method comprises the following steps: (1) Preparation of high thermal conductivity carbon fiber preform; (2) alternately depositing a silicon carbide interface layer and a boron nitride nanosheet interface layer on the fiber surface of the high thermal conductivity carbon fiber preform by chemical vapor deposition until a preset thickness or a preset number of layers is reached to obtain an intermediate body containing an anti-oxidation alternating interface layer; (3) performing a first densification on the intermediate body by a PIP process of impregnation / curing / cracking using a polycarbosilane ceramic precursor solution and a zirconium-based ceramic precursor solution as impregnation liquids, thereby obtaining a first densified composite material; (4) subjecting the first densified composite material to a high temperature treatment, and then subjecting the first densified composite material to a second densification by a PIP process of impregnation / curing / cracking using a polyborosilazane ceramic precursor solution as an impregnation liquid to obtain a second densified composite material; (5) Alternately depositing a silicon carbide coating and a boron nitride nanosheet coating on the surface of the second densified composite material by chemical vapor deposition until a preset thickness or a preset number of layers is reached, thereby obtaining a wide temperature range reusable high thermal conductivity composite material; in steps (2) and (5), depositing the boron nitride nanosheet interface layer and the boron nitride nanosheet coating in an atmosphere containing nitrogen, hydrogen, boron trichloride gas and ammonia, wherein the molar ratio of nitrogen, hydrogen, boron trichloride gas and ammonia is (18-20): (1-2): (1-2): (1-1.5), and the deposition temperature is 900-1100°C.

4. The preparation method according to claim 3, characterized in that In step (1): A carbon fiber preform is formed by weaving a mixture of high thermal conductivity carbon fiber and polyacrylonitrile-based carbon fiber or weaving a carbon fiber preform with high thermal conductivity carbon fiber, and then graphitizing the preform to obtain a high thermal conductivity carbon fiber preform.

5. The preparation method according to claim 4, characterized in that: The volume fraction of carbon fibers in the high thermal conductivity carbon fiber preform is 30-40%, and the density of the high thermal conductivity carbon fiber preform is 0.6-0.9 g / cm 3 .

6. The preparation method according to claim 4, characterized in that: The temperature of the graphitization treatment is 2800-3200° C., and the time is 0.5-1 hour.

7. The preparation method according to claim 3, characterized in that In step (1), the preparation of the high thermal conductivity carbon fiber preform includes the following sub-steps: (a) dispersing mesophase pitch-based carbon fiber bundles by mechanical vibration and / or ultrasonic vibration, and then fixing them with hot-melt filaments to obtain unidirectional pitch-based carbon fiber cloth; (b) After laminating unidirectional asphalt-based carbon fiber cloth, polyacrylonitrile-based carbon fiber is used to sew them together to obtain a high thermal conductivity carbon fiber preform.

8. The preparation method according to claim 3, characterized in that In step (2): The number of layers of the silicon carbide interface layer and the boron nitride nanosheet interface layer are both n layers, where n is 2 to 4 and is a natural number; When depositing the silicon carbide interface layer, the deposition temperature is 1000-1100° C., and the thickness of the single-layer silicon carbide interface layer is 0.1-0.2 μm; The thickness of the interface layer of a single-layer boron nitride nanosheet is 0.1~0.2μm.

9. The preparation method according to claim 8, characterized in that: The thickness ratio of the monolayer silicon carbide interface layer to the monolayer boron nitride nanosheet interface layer is (0.8~1.2):

1.

10. The preparation method according to claim 3, characterized in that: In step (3): first, using a polycarbosilane ceramic precursor solution as an impregnation liquid to perform a PIP process of impregnation / curing / cracking for 3 to 5 times, the cracking temperature is 900 to 1200°C, and the time for each cracking is 2 to 4 hours, and then using a zirconium-based ceramic precursor solution as an impregnation liquid to perform a PIP process of impregnation / curing / cracking for 5 to 10 times, the cracking temperature is 1400 to 1500°C, and the time for each cracking is 2 to 4 hours; and / or In step (4): the temperature of the high temperature treatment is 1600°C to 2000°C, the time is 3 to 5 hours, and / or the high temperature treatment is carried out under an inert atmosphere, and / or a polyborosilazane ceramic precursor solution is used as an impregnation liquid to carry out 8 to 15 rounds of impregnation / curing / cracking PIP process, the cracking temperature is 1000 to 1300°C, and the time of each cracking is 2 to 4 hours.

11. The preparation method according to claim 3, characterized in that In step (5): The number of layers of the silicon carbide coating and the boron nitride nanosheet coating are both m layers, where m is 2 to 4 and is a natural number; When depositing the silicon carbide coating, the deposition temperature is 1000-1100° C., and the thickness of the single-layer silicon carbide coating is 15-20 μm; The thickness of the single-layer boron nitride nanosheet coating is 15~20μm.

12. The preparation method according to claim 11, characterized in that: The thickness ratio of the single-layer silicon carbide coating to the single-layer boron nitride nanosheet coating is (0.8~1.2):

1.

13. The preparation method according to claim 11, characterized in that: Silicon carbide coatings and boron nitride nanosheet coatings are alternately deposited to form an oxidation-resistant alternating ceramic coating, wherein the total thickness of the oxidation-resistant alternating ceramic coating is 60 to 160 μm.

14. The preparation method according to any one of claims 3 to 13, characterized in that: The polycarbosilane ceramic precursor solution, the zirconium-based ceramic precursor solution and the polyborosilazane ceramic precursor solution all contain boron nitride nanosheets; The mass fraction of boron nitride nanosheets in the polycarbosilane ceramic precursor solution is 2-3%; The zirconium-based ceramic precursor solution contains boron nitride nanosheets at a mass fraction of 4-6%; The mass fraction of boron nitride nanosheets contained in the polyborosilazane ceramic precursor solution is 2-3%.

15. The preparation method according to claim 14, characterized in that: The boron nitride nanosheets have a sheet diameter of 1-2 μm and a thickness of 60-120 nm.

16. A high thermal conductivity composite material that is reusable over a wide temperature range and is obtained by the method according to any one of claims 3 to 15.

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