A heat-conducting ceramic-based composite material with a contoured structure and a preparation method thereof

Abstract

The present invention relates to a heat-conducting ceramic-based composite material with a contoured structure and a preparation method thereof. The method comprises the following steps: weaving polyacrylonitrile-based carbon fibers into unidirectional carbon fiber cloth for the circumferential direction, and mixing polyacrylonitrile-based carbon fibers with mesophase pitch-based carbon fibers to form unidirectional carbon fiber cloth for the height direction; alternately laying the two unidirectional carbon fiber cloths on the surface of a tooling, and treating the wall thickness direction with a mixed fiber bundle of polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers; preparing a carbon interface layer by chemical vapor deposition and graphitizing the resultant to obtain a carbon fiber intermediate blank; and adopting a precursor impregnation and cracking process to react a ceramic precursor solution with the carbon fiber intermediate blank to obtain a heat-conducting ceramic-based composite material with a contoured structure. The present invention can prepare a heat-conducting ceramic-based composite material with a contoured structure by near-net-size molding. The obtained material has low density, high specific strength, uniform and dense internal structure, and has a heat-conducting advantage, especially in the wall thickness direction.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials and preparation thereof, and in particular relates to a heat-conducting ceramic-based composite material with a contoured structure and a preparation method thereof. Background Art

[0002] High thermal conductivity carbon fiber has the characteristics of high thermal conductivity, high modulus, high strength, low expansion coefficient, high electrical conductivity, etc. It also has the characteristics of high temperature resistance, corrosion resistance, ablation resistance, high temperature and high strength, large damping, earthquake resistance and deformation resistance. Due to its low density, it has high specific thermal conductivity, specific modulus and specific strength, and has dual-use characteristics. It is one of the excellent structural and functional integrated materials. The thermal conductivity composite material prepared from it has excellent thermal and mechanical properties and strong structural designability, and can be used in aerospace, nuclear energy, precision electronic equipment and other application environments. However, the high modulus of high thermal conductivity carbon fiber leads to its disadvantages of low elongation at break, high brittleness, and difficulty in small-angle bending, which makes its application process difficult. It is easy to have hair and broken wires during use, and it is difficult to prepare prepregs and contoured structural preforms.

[0003] Thermally conductive ceramic-based composites typically use high-thermal conductivity pitch-based carbon fibers as reinforcement. However, the modulus of high-thermal conductivity mesophase pitch-based carbon fibers is very high, and their structure and performance are significantly different from those of traditional polyacrylonitrile-based carbon fibers, resulting in differences in the weaving of the fiber preform, the heat treatment process, and the densification of the ceramic matrix. In addition, thermally conductive ceramic-based composite products generally do not have a regular structure, and existing thermally conductive ceramic-based composites can only be prepared in regular blocks and then processed into the required structure and size. This processing will damage the performance of the composite material and result in waste of the composite material.

[0004] Therefore, it is very necessary to provide a contoured thermally conductive ceramic-based composite material and a preparation method thereof, which can adapt to the performance requirements of the product on the material in different directions while saving costs. Summary of the Invention

[0005] In order to solve one or more technical problems existing in the prior art, the present invention provides a thermally conductive ceramic-based composite material with a contoured structure and a preparation method thereof.

[0006] In a first aspect, the present invention provides a method for preparing a heat-conducting ceramic-based composite material having a contoured structure, wherein the contoured structure includes a circumferential direction, a wall thickness direction, and a height direction, and the preparation method comprises the following steps:

[0007] (1) weaving polyacrylonitrile-based carbon fibers into a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure, and weaving a mixture of polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers into a unidirectional carbon fiber cloth for the height direction of the profiling structure;

[0008] (2) Laying a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and a unidirectional carbon fiber cloth for the height direction of the profiling structure on the surface of a forming tool to obtain a cloth layer structure having a preset wall thickness, and performing 2.5D weaving and / or three-dimensional puncture on the cloth layer structure in the wall thickness direction using a fiber bundle composed of a mixture of polyacrylonitrile-based carbon fiber and mesophase pitch-based carbon fiber to obtain a carbon fiber preform of the profiling structure;

[0009] (3) preparing a carbon interface layer on the fiber surface of the contoured carbon fiber preform by chemical vapor deposition and performing graphitization treatment to obtain a carbon fiber intermediate blank;

[0010] (4) A precursor impregnation and cracking process is used to react the ceramic precursor solution with the carbon fiber intermediate body to produce a contoured thermally conductive ceramic-based composite material.

[0011] Preferably, in step (1), the polyacrylonitrile-based carbon fiber is one or more of T300, T700, and T1000; the surface density of the unidirectional carbon fiber cloth in the circumferential direction of the profiling structure is 200 to 300 g / m 2 The thermal conductivity of the mesophase pitch-based carbon fiber after graphitization treatment is not less than 800W / (m·K); in the unidirectional carbon fiber cloth used in the height direction of the profiling structure, the volume fraction ratio of the mesophase pitch-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1-3):1; and / or the surface density of the unidirectional carbon fiber cloth used in the height direction of the profiling structure is 200-300g / m 2 .

[0012] Preferably, in step (2): the ply is: alternately plying in the order of 1 layer of unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and 1 to 2 layers of unidirectional carbon fiber cloth for the height direction of the profiling structure; and / or the preset wall thickness is 10 to 20 mm.

[0013] Preferably, in step (2): in the fiber bundle, the volume fraction ratio of the mesophase asphalt-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1 to 3): 1; the specification of the fiber bundle is 2K to 4K; and / or the volume fraction of the carbon fiber in the contoured structural carbon fiber preform is 35 to 45%, and the volume fraction of the carbon fiber along the height direction is 10 to 18%.

[0014] Preferably, the thickness of the carbon interface layer is 50 to 200 nm; the temperature of the graphitization treatment is 2800 to 3200° C., and the time of the graphitization treatment is 15 to 30 minutes; and / or the profiling structure is a cylindrical structure, and the forming tool is a cylindrical graphite tool.

[0015] Preferably, a precursor impregnation and cracking process is carried out using a ceramic precursor solution containing one or more ceramic precursors of SiC, HfC, TaC, ZrC, and ZrB2; the solid content of the ceramic precursor solution is 50% to 70%; in the precursor impregnation and cracking process, the cracking temperature is 1400 to 1700°C, the cracking time is 2 to 4 hours; and / or the precursor impregnation and cracking are repeated 15 to 20 times.

[0016] Preferably, the ceramic precursor solution further contains graphene nanosheets and boron nitride nanosheets; the mass ratio of the ceramic precursor, graphene nanosheets and boron nitride nanosheets in the ceramic precursor solution is (80-90): (8-12): (4-6).

[0017] Preferably, the ceramic precursor solution is prepared by adding a ceramic precursor, graphene nanosheets and boron nitride nanosheets to a solvent, and then stirring and ultrasonically treating the resulting solution; the graphene nanosheets have a sheet diameter of 5 to 10 μm and a thickness of 3 to 10 nm; and / or the boron nitride nanosheets have a sheet diameter of 1 to 2 μm and a thickness of 60 to 120 nm.

[0018] In a second aspect, the present invention provides a heat-conducting ceramic-based composite material with a contoured structure, which is prepared by the preparation method described in the first aspect of the present invention.

[0019] Preferably, the contoured heat-conducting ceramic-based composite material has one or more of the following properties:

[0020] Density is 2.5-3.5g / cm 3 ;

[0021] The profiling structure is a cylindrical structure, the outer contour of the cylindrical structure has a diameter of not less than 300 mm, the height of the cylindrical structure is not less than 300 mm, and the wall thickness of the cylindrical structure is 10 to 20 mm;

[0022] Flexural strength is 200-360 MPa;

[0023] The thermal conductivity in the wall thickness direction is 80~190W / (m·K).

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] (1) The method of the present invention can prepare heat-conducting ceramic-based composite materials with a contoured structure (e.g., a cylindrical structure) by forming the composite materials with near-net-size, and the fiber ratio and matrix composition can be controlled. The heat-conducting ceramic-based composite materials with a contoured structure prepared by the present invention have low density, high specific strength, uniform and dense internal structure, and have the advantage of heat conduction in a specific direction, especially in the wall thickness direction.

[0026] (2) The method of the present invention uses polyacrylonitrile-based carbon fibers and mesophase asphalt-based carbon fibers mixed in proportion for weaving in the diameter and height directions of the contoured structure. The two fibers mixed in proportion can have both good thermal conductivity and weavability, can be bent, and are suitable for contoured weaving; the fiber ratio and matrix composition can be controlled, and are particularly suitable for samples with a cylinder as the basic contoured structure.

[0027] (3) The method of the present invention can form near-net size, saving the cost of raw materials such as fibers and precursors, and reducing processing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the heat-conducting ceramic-based composite material with a contoured structure obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] In a first aspect, the present invention provides a method for preparing a thermally conductive ceramic matrix composite material having a contoured structure, wherein the contoured structure includes a circumferential direction (denoted as the X direction), a wall thickness direction (denoted as the Y direction), and a height direction (denoted as the Z direction), and the preparation method comprises the following steps:

[0031] (1) weaving polyacrylonitrile-based carbon fibers into a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure, and weaving polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers into a unidirectional carbon fiber cloth for the height direction of the profiling structure; it should be noted that in the unidirectional carbon fiber cloth, the "unidirectional" here means that in the same piece (same layer) of carbon fiber cloth, the carbon fibers are arranged along one direction, specifically, in the unidirectional carbon fiber cloth for the circumferential direction of the profiling structure, the carbon fibers are arranged along the circumferential direction of the profiling structure, and in the unidirectional carbon fiber cloth for the height direction of the profiling structure, the carbon fibers are arranged along the height direction of the profiling structure;

[0032] (2) Laying a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and a unidirectional carbon fiber cloth for the height direction of the profiling structure on the surface of a forming tool to obtain a cloth layer structure having a preset wall thickness, and performing 2.5D weaving and / or three-dimensional puncture (three-dimensional puncture weaving) on ​​the cloth layer structure in the wall thickness direction using a fiber bundle formed by mixing polyacrylonitrile-based carbon fiber and mesophase pitch-based carbon fiber to obtain a carbon fiber preform of the profiling structure;

[0033] (3) preparing a carbon interface layer on the fiber surface of the contoured carbon fiber preform by chemical vapor deposition and performing graphitization treatment to obtain a carbon fiber intermediate blank; the present invention does not specifically limit the process conditions of the chemical vapor deposition method, which is a conventional technology in the field;

[0034] (4) A precursor impregnation and cracking process is used to react a ceramic precursor solution with a carbon fiber intermediate blank to obtain a contoured thermally conductive ceramic-based composite material. In the present invention, for example, a ceramic precursor solution containing one or more ceramic precursors is used to perform multiple rounds of precursor impregnation and cracking processes on the carbon fiber intermediate blank to prepare a dense ceramic matrix. A very thin ceramic coating is also formed near the surface of the material to obtain a contoured thermally conductive ceramic-based composite material. The ceramic matrix can be, for example, one, two or more ceramic materials in combination (for example, SiC-ZrB2, SiC-HfC, SiC-HfC-TaC or SiC-HfC-ZrC, etc.).

[0035] In the present invention, it is preferred that the basic configuration of the profiling structure is cylindrical (cylindrical structure), and the directions include the circumferential direction along the circumference (denoted as the X direction), the wall thickness direction of the cylinder (or the diameter direction, denoted as the Y direction), and the height direction of the cylinder (denoted as the Z direction). Polyacrylonitrile-based carbon fibers are contained in all three directions, and mesophase asphalt-based carbon fibers are arranged in the Y direction or the Y and Z directions as high-speed heat conduction channels. The matrix adopts one, two or more combinations of ceramic materials (such as SiC-ZrB2, SiC-HfC, SiC-HfC-TaC, SiC-HfC-ZrC, etc.). The method of the present invention adopts polyacrylonitrile-based carbon fiber and mesophase asphalt-based carbon fiber mixed in proportion and used for weaving in the diameter direction (wall thickness direction) and height direction of the profiled structure. After the two fibers are mixed in proportion, they can have both good thermal conductivity and weavability, can be bent, and are suitable for profiled weaving. They can be formed to near net size to prepare heat-conducting ceramic-based composite materials with profiled cylindrical structures, and the profiled structure can be directly formed without the need to first prepare regular blocks and then process them into the required structure and size like existing heat-conducting ceramic-based composite materials. This will not cause damage to the performance of the composite material, nor will it cause waste of the composite material, saving the cost of raw materials such as fibers and precursors, reducing processing costs, and the fiber ratio and matrix composition in the present invention can be controlled. The composite material thus obtained has low density, high specific strength, uniform and dense internal structure, and has a specific directional heat conduction advantage, especially in the wall thickness direction.

[0036] According to some specific embodiments, the preparation of the heat-conducting ceramic-based composite material with a contoured structure is as follows:

[0037] ① Weave polyacrylonitrile-based carbon fibers into unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for use in the X direction;

[0038] ② Mix polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers in a certain proportion and weave them into a unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for use in the Z direction;

[0039] ③ The unidirectional carbon fibers prepared in steps ① and ② are laid on the surface of the cylindrical graphite tooling, and are laid in a specified direction and a certain proportion to obtain a cloth layer structure;

[0040] ④ In the wall thickness direction, the above-mentioned cloth layer structure is 2.5D weaving and / or three-dimensionally puncturing using a fiber bundle formed by mixing polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers in proportion to obtain a contoured carbon fiber preform;

[0041] ⑤Use chemical vapor deposition to uniformly deposit a carbon interface layer on the fiber surface of the contoured carbon fiber preform and perform graphitization treatment to obtain a carbon fiber intermediate blank;

[0042] ⑥ Using a polymer precursor solution (ceramic precursor solution) corresponding to the ceramic matrix, the carbon fiber intermediate body is subjected to multiple rounds of precursor impregnation-curing-cracking process to prepare a dense ceramic matrix and a ceramic coating, and finally the contoured structure heat-conducting ceramic-based composite material is obtained.

[0043] According to some preferred embodiments, in step (1): in the unidirectional carbon fiber cloth used in the circumferential direction of the profiling structure and the unidirectional carbon fiber cloth used in the height direction of the profiling structure, the polyacrylonitrile-based carbon fiber is one or more of T300, T700, and T1000; the surface density of the unidirectional carbon fiber cloth used in the circumferential direction of the profiling structure is 200 to 300 g / m 2 (e.g. 200, 220, 240, 260, 280 or 300 g / m 2 ); the thermal conductivity of the mesophase pitch-based carbon fiber after graphitization treatment is not less than 800W / (m·K), the temperature of the graphitization treatment is 2800-3200°C, and the time of the graphitization treatment is 15-30min, that is, after the graphitization treatment in step (3) of the present invention, the thermal conductivity of the mesophase pitch-based carbon fiber used is not less than 800W / (m·K); in the unidirectional carbon fiber cloth for the height direction of the profiling structure, the volume fraction ratio of the mesophase pitch-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1-3):1 (for example, 1:1, 1.5:1, 2:1, 2.5:1 or 3:1); and / or the surface density of the unidirectional carbon fiber cloth for the height direction of the profiling structure is 200-300g / m 2 (e.g. 200, 220, 240, 260, 280 or 300 g / m 2 ).

[0044] According to some preferred embodiments, in step (2), the ply laying is performed alternately according to the plying order of 1 layer of unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and 1 to 2 layers of unidirectional carbon fiber cloth for the height direction of the profiling structure. In other words, the alternating plying method of the present invention is: 1 layer of unidirectional carbon fiber cloth for the circumferential direction of the profiling structure + 1 layer of unidirectional carbon fiber cloth for the height direction of the profiling structure or 1 layer of unidirectional carbon fiber cloth for the circumferential direction of the profiling structure + 2 layers of unidirectional carbon fiber cloth for the height direction of the profiling structure, and the layers are laid in sequence according to a regular pattern until the wall thickness requirement is met, that is, the ratio of the number of fiber cloth layers in the X direction and the Z direction is 1:1 or 1:2; and / or the preset wall thickness is 10 to 20 mm (for example, 10, 12, 14, 16, 18 or 20 mm).

[0045] According to some preferred embodiments, in step (2): in the fiber bundle, the volume fraction ratio of the mesophase pitch-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1 to 3): 1 (e.g., 1:1, 1.5:1, 2:1, 2.5:1, or 3:1), the thermal conductivity of the mesophase pitch-based carbon fiber after graphitization treatment is not less than 800 W / (m·K), the temperature of the graphitization treatment is 2800 to 3200°C, and the time of the graphitization treatment is 15 to 30 min, that is, after the graphitization treatment in step (3) of the present invention, the thermal conductivity of the mesophase pitch-based carbon fiber used is not less than 800 W / (m·K). ; The polyacrylonitrile-based carbon fiber is one or more of T300, T700, and T1000; the specification of the fiber bundle is 2K to 4K (for example, 2K, 3K, or 4K); and / or the volume fraction of the carbon fiber in the contoured structural carbon fiber preform is 35 to 45% (for example, 35%, 38%, 41%, or 45%), the volume fraction of the carbon fiber along the height direction is 10 to 18% (for example, 10%, 12%, 14%, 16%, or 18%), and the volume fraction of the carbon fiber along the wall thickness direction is 8 to 15% (for example, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%).

[0046] According to some preferred embodiments, in step (3): the thickness of the carbon interface layer is 50 to 200 nm (for example, 50, 100, 150 or 200 nm); and / or the temperature of the graphitization treatment is 2800 to 3200°C (for example, 2800°C, 2900°C, 3000°C, 3100°C or 3200°C), and the time of the graphitization treatment is 15 to 30 min (for example, 15, 20, 25 or 30 min).

[0047] According to some preferred embodiments, the profiling structure is a cylindrical structure. Specifically, the profiling structure is a cylindrical structure with a hollow interior, for example, Figure 1 As shown; the forming tool is a cylindrical graphite tool.

[0048] According to some preferred embodiments, a precursor impregnation and cracking process is carried out using a ceramic precursor solution containing one or more ceramic precursors of SiC, HfC, TaC, ZrC, and ZrB2; the solid content of the ceramic precursor solution is 50% to 70% (for example, 50, 55, 60, 65 or 70%), and the viscosity of the ceramic precursor solution is, for example, 100 to 300 mPa·s (for example, 100, 150, 200, 250 or 300 mPa·s); in the precursor impregnation and cracking process, the cracking temperature is 1400 to 1700°C (for example, 1400, 1500, 1600 or 1700°C), the cracking time is 2 to 4h (for example, 2, 3 or 4h); and / or the number of times the precursor impregnation and cracking is repeated is 15 to 20 times; the present invention does not specifically limit the process conditions of impregnation and curing in the precursor impregnation and cracking process, which is a conventional technology in this field.

[0049] According to some specific embodiments, the impregnation-curing-cracking process includes: using SiC-ZrB2, SiC-HfC, SiC-HfC-TaC, SiC-HfC-ZrC corresponding mixed ceramic precursor solutions for impregnation-curing-cracking three steps, wherein the viscosity of the ceramic precursor solution is in the range of 100 to 300 mPa·s, the solid content is 50 to 70%, the cracking temperature is 1400°C to 1700°C, and the cracking time is 2h to 4h; the three steps of precursor impregnation-curing-cracking are repeated for 15 to 20 rounds until the weight gain of the composite material after the last cracking is less than 1%, thereby obtaining a cylindrical profile structure thermal conductivity ceramic-based composite material.

[0050] According to some preferred embodiments, the ceramic precursor solution also contains graphene nanosheets and boron nitride nanosheets; the present invention does not specifically limit the sources of graphene nanosheets and boron nitride nanosheets, and products that can be directly purchased on the market or products synthesized by existing methods can be used; the mass ratio of ceramic precursor, graphene nanosheets and boron nitride nanosheets contained in the ceramic precursor solution is (80-90): (8-12): (4-6); the ceramic precursor solution uses xylene as a solvent; the present invention has no special requirements for xylene, which can be one or more of o-xylene, p-xylene, and m-xylene.

[0051] In the present invention, the ceramic precursor solution preferably further comprises graphene nanosheets and boron nitride nanosheets, and the mass ratio of the ceramic precursor, graphene nanosheets and boron nitride nanosheets is (80-90): (8-12): (4-6). The present invention finds that adding an appropriate amount of graphene nanosheets and boron nitride nanosheets to the ceramic precursor solution and performing a precursor impregnation and cracking process can achieve a significant improvement in the bending strength and in-plane thermal conductivity of the contoured thermal conduction ceramic matrix composite material, making it have high temperature, high strength and high thermal conductivity. The invention has broad application prospects in the required fields; the possible reason is that the addition of graphene nanosheets and boron nitride nanosheets can form a good interface structure with ceramic particles in the precursor impregnation and cracking process, which can improve the overall strength and heat resistance of the material and enhance the bending strength of the material. In addition, graphene nanosheets and boron nitride nanosheets have excellent thermal conductivity. Graphene nanosheets and boron nitride nanosheets are distributed throughout the material to form effective heat conduction channels and heat conduction networks, which help to quickly transfer heat, thereby improving the overall thermal conductivity of the material.

[0052] According to some preferred embodiments, the ceramic precursor solution is prepared as follows: ceramic precursor, graphene nanosheets and boron nitride nanosheets are added to a solvent, and then stirred and ultrasonically treated to obtain; 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, 40 to 60 minutes; in the present invention, the ceramic precursor, graphene nanosheets and boron nitride nanosheets are uniformly dispersed in the solvent by stirring and ultrasonic treatment. The method is to uniformly distribute the graphene nanosheets and the boron nitride nanosheets in the entire ceramic precursor solution as much as possible, thereby facilitating the improvement of the uniformity of the thermally conductive ceramic-based composite material with a contoured structure and helping to ensure the performance of the material. In the present invention, when the ceramic precursor is a mixed ceramic precursor, for example, a mixed ceramic precursor of polycarbosilane and polyzirconoxane, the ceramic precursor solution further contains a carbon precursor. The ceramic precursor solution is prepared by adding the ceramic precursor, the carbon source precursor, the graphene nanosheets and the boron nitride nanosheets to the solvent, and then stirring and ultrasonically treating the mixture to obtain the resultant.

[0053] According to some preferred embodiments, the diameter of the graphene nanosheet is 5 to 10 μm and the thickness is 3 to 10 nm; and / or the diameter of the boron nitride nanosheet is 1 to 2 μm and the thickness is 60 to 120 nm; in the present invention, preferably the diameter of the graphene nanosheet is 5 to 10 μm and the thickness is 3 to 10 nm, the diameter of the boron nitride nanosheet is 1 to 2 μm and the thickness is 60 to 120 nm, the addition of graphene nanosheets with smaller thickness and larger sheet diameter and boron nitride nanosheets with larger thickness and smaller sheet diameter, stone The appropriate size difference between graphene nanosheets and boron nitride nanosheets enables them to be effectively dispersed in the composite material and form an appropriate microscopic concave-convex structure interface with the ceramic particles. The appropriate concave-convex structure helps to improve the compatibility of the interface, better interface matching, increase the effective area of ​​the interface, reduce stress concentration, and help enhance the strength of the material. In addition, the small thickness and large diameter of the graphene nanosheets make it a very effective heat conduction channel, which helps to transfer heat quickly. The synergistic effect between the two can further improve the overall thermal conductivity and strength of the material.

[0054] In a second aspect, the present invention provides a heat-conducting ceramic-based composite material with a contoured structure, which is prepared by the preparation method described in the first aspect of the present invention.

[0055] According to some preferred embodiments, the contoured heat-conducting ceramic-based composite material has one or more of the following properties:

[0056] Density is 2.5-3.5g / cm 3 ;

[0057] The profiling structure is a cylindrical structure, the outer contour of the cylindrical structure has a diameter of not less than 300 mm, the height of the cylindrical structure is not less than 300 mm, and the wall thickness of the cylindrical structure is 10 to 20 mm;

[0058] Flexural strength is 200-360 MPa;

[0059] The thermal conductivity in the wall thickness direction is 80~190W / (m·K).

[0060] 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.

[0061] Example 1

[0062] ① Weave T300 polyacrylonitrile-based carbon fiber into unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for use in the X direction (circumferential direction). The surface density of the unidirectional carbon fiber cloth is 220g / m 2 .

[0063] ②T300 polyacrylonitrile-based carbon fiber and mesophase pitch-based carbon fiber are mixed and woven into a unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for use in the Z direction (height direction). The surface density of the unidirectional carbon fiber cloth in this step is 260g / m 2 The volume fraction ratio of mesophase pitch-based carbon fiber to polyacrylonitrile-based carbon fiber is 3:1.

[0064] ③ The unidirectional carbon fiber cloth prepared in steps ① and ② is laid on the surface of the cylindrical graphite tooling to obtain a cloth layer structure. The specific laying is to alternately lay the fiber cloth layers of the unidirectional carbon fiber cloth for the circumferential direction and the unidirectional carbon fiber cloth for the height direction in a ratio of 1:1, that is, 1 layer of unidirectional carbon fiber cloth for the circumferential direction + 1 layer of unidirectional carbon fiber cloth for the height direction are alternately laid, and the layers are alternately laid in a regular pattern until the wall thickness reaches 15 mm.

[0065] ④ In the wall thickness direction, the above-mentioned cloth layer structure is 2.5D woven using a fiber bundle formed by a mixture of T300 polyacrylonitrile-based carbon fiber and mesophase asphalt-based carbon fiber to obtain a contoured structural carbon fiber preform, wherein the volume fraction ratio of the mesophase asphalt-based carbon fiber to the polyacrylonitrile-based carbon fiber is 2:1, and the specification of the fiber bundle is 3K; the volume fraction of the carbon fiber in the obtained contoured structural carbon fiber preform is 40%, and the volume fraction of the carbon fiber along the Z direction (height direction) is 15%.

[0066] ⑤ A carbon interface layer was uniformly deposited on the fiber surface of the contoured carbon fiber preform by chemical vapor deposition and graphitized to obtain a carbon fiber intermediate body; the thickness of the carbon interface layer was 100 nm, the graphitization temperature was 2900 ° C, and the graphitization time was 20 min.

[0067] ⑥ A precursor impregnation and cracking process is used to react a ceramic precursor solution containing silicon carbide and hafnium carbide with a carbon fiber intermediate body to obtain a contoured thermally conductive ceramic matrix composite material; the ceramic precursor solution is prepared by uniformly mixing polycarbosilane, polyhafnium oxide and furfural resin (carbon source precursor) with xylene to obtain a ceramic precursor solution, wherein the amount ratio of polycarbosilane to polyhafnium oxide is such that the molar ratio of silicon to hafnium in the ceramic precursor solution is 5:1, and the amount of polycarbosilane to polyhafnium oxide is 5:1. The mass ratio of the sum to the amount of the furfural resin is 10:1, and the sum of the mass percentages of polycarbosilane, polyhafnium oxide and furfural resin in the ceramic precursor solution is 60%; in the precursor impregnation and cracking process, the impregnation is carried out at room temperature, the impregnation time is 2 hours, the impregnation pressure is 1.5 MPa, the curing temperature is 250°C, the curing time is 3 hours, the curing pressure is 2 MPa, the cracking temperature is 1500°C, the cracking time is 3 hours, and the precursor impregnation and cracking process is repeated 15 times.

[0068] Example 2

[0069] Example 2 is basically the same as Example 1, except that:

[0070] ⑥ A precursor impregnation and cracking process is used to react a ceramic precursor solution with a carbon fiber intermediate body to obtain a contoured thermally conductive ceramic-based composite material; the ceramic precursor solution is prepared by adding polycarbosilane, polyhafnium oxide, furfural resin (carbon source precursor), graphene nanosheets with a sheet size distribution range of 5 to 10 μm and a thickness distribution range of 3 to 10 nm, and boron nitride nanosheets with a sheet size 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 obtained mixture, first stirring at a stirring speed of 400 rpm for 40 minutes, and then ultrasonically treating the obtained mixture at a frequency of 20 kHz for 50 minutes; the amount ratio of polycarbosilane to polyhafnium oxide is such that the ceramic precursor solution contains The molar ratio of silicon to hafnium is 5:1; the mass ratio of the sum of the amounts of polycarbosilane and polyhafnium oxide to the amount of the furfural resin is 10:1, and the mass ratio of the sum of the masses of polycarbosilane and polyhafnium oxide to the graphene nanosheets and boron nitride nanosheets is 88:8:4; the sum of the mass percentages of polycarbosilane, polyhafnium oxide, furfural resin, graphene nanosheets and boron nitride nanosheets contained in the ceramic precursor solution is 60%; in the precursor impregnation and cracking process, the impregnation is carried out at room temperature, the impregnation time is 2 hours, the impregnation pressure is 1.5 MPa, the curing temperature is 250°C, the curing time is 3 hours, the curing pressure is 2 MPa, the cracking temperature is 1500°C, the cracking time is 3 hours, and the precursor impregnation and cracking process is repeated 15 times.

[0071] Example 3

[0072] Example 3 is basically the same as Example 2, except that:

[0073] ⑥ A precursor impregnation and cracking process is used to react a ceramic precursor solution with a carbon fiber intermediate body to obtain a contoured thermally conductive ceramic-based composite material; the ceramic precursor solution is prepared by adding polycarbosilane, polyhafnium oxide, furfural resin (carbon source precursor) and graphene nanosheets with a sheet diameter distribution range of 5 to 10 μm and a thickness distribution range of 3 to 10 nm to xylene, and then stirring and ultrasonically treating the obtained product, first stirring at a stirring speed of 400 rpm for 40 minutes, and then ultrasonically treating at a frequency of 20 kHz for 50 minutes; the amount ratio of polycarbosilane to polyhafnium oxide is such that the molar ratio of silicon contained in the ceramic precursor solution to hafnium contained is 5:1, the mass ratio of the sum of the amounts of polycarbosilane and polyhafnium oxide to the amount of the furfural resin is 10:1, and the mass ratio of the sum of the masses of polycarbosilane and polyhafnium oxide to the graphene nanosheets is 88:12; the ceramic precursor solution contains 60% of the sum of the mass percentages of polycarbosilane, polyhafnium oxide, furfural resin and graphene nanosheets; in the precursor impregnation and cracking process, the impregnation is carried out at room temperature, the impregnation time is 2 hours, the impregnation pressure is 1.5 MPa, the curing temperature is 250°C, the curing time is 3 hours, the curing pressure is 2 MPa, the cracking temperature is 1500°C, the cracking time is 3 hours, and the precursor impregnation and cracking process is repeated 15 times.

[0074] Example 4

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

[0076] ⑥ A precursor impregnation and cracking process is used to react a ceramic precursor solution with a carbon fiber intermediate body to obtain a contoured thermally conductive ceramic-based composite material; the ceramic precursor solution is prepared by adding polycarbosilane, polyhafnium oxide, furfural resin (carbon source 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 to xylene, and then stirring and ultrasonically treating the obtained product, first stirring at a stirring speed of 400 rpm for 40 minutes, and then ultrasonically treating at a frequency of 20 kHz for 50 minutes; the amount ratio of polycarbosilane to polyhafnium oxide is such that the molar ratio of silicon contained in the ceramic precursor solution to hafnium contained is 5:1, the mass ratio of the sum of the amounts of polycarbosilane and polyhafnium oxide to the amount of the furfural resin is 10:1, and the mass ratio of the sum of the masses of polycarbosilane and polyhafnium oxide to the boron nitride nanosheets is 88:12; the ceramic precursor solution contains 60% of the sum of the mass percentages of polycarbosilane, polyhafnium oxide, furfural resin and boron nitride nanosheets; in the precursor impregnation and cracking process, the impregnation is carried out at room temperature, the impregnation time is 2 hours, the impregnation pressure is 1.5 MPa, the curing temperature is 250°C, the curing time is 3 hours, the curing pressure is 2 MPa, the cracking temperature is 1500°C, the cracking time is 3 hours, and the precursor impregnation and cracking process is repeated 15 times.

[0077] Comparative Example 1

[0078] ① Weave T300 polyacrylonitrile-based carbon fiber into unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for use in the X direction (circumferential direction). The surface density of the unidirectional carbon fiber cloth is 220g / m 2 .

[0079] ② Weave T300 polyacrylonitrile-based carbon fiber into unidirectional carbon fiber cloth (unidirectional carbon fiber cloth) for the Z direction (height direction). The surface density of the unidirectional carbon fiber cloth in this step is 260g / m 2 .

[0080] ③ The unidirectional carbon fiber cloth prepared in steps ① and ② is laid on the surface of the cylindrical graphite tooling to obtain a cloth layer structure. The specific laying is to alternately lay the fiber cloth layers of the unidirectional carbon fiber cloth for the circumferential direction and the unidirectional carbon fiber cloth for the height direction in a ratio of 1:1, that is, 1 layer of unidirectional carbon fiber cloth for the circumferential direction + 1 layer of unidirectional carbon fiber cloth for the height direction are alternately laid, and the layers are alternately laid in a regular pattern until the wall thickness reaches 15 mm.

[0081] ④ The above-mentioned cloth layer structure is 2.5D woven in the wall thickness direction using a fiber bundle formed by T300 polyacrylonitrile-based carbon fiber to obtain a contoured carbon fiber preform, and the specification of the fiber bundle is 3K; the volume fraction of carbon fiber in the obtained contoured carbon fiber preform is 40%, and the volume fraction of carbon fiber along the Z direction (height direction) is 15%.

[0082] ⑤ is the same as step ⑤ of Example 1.

[0083] ⑥ is the same as step ⑥ of Example 1.

[0084] Comparative Example 2

[0085] ① is the same as step ① in Example 1.

[0086] ② is the same as step ② of Example 1.

[0087] ③ is the same as step ③ of Example 1.

[0088] ④ The above-mentioned cloth layer structure is 2.5D woven in the wall thickness direction using a fiber bundle formed by T300 polyacrylonitrile-based carbon fiber to obtain a contoured carbon fiber preform, and the specification of the fiber bundle is 3K; the volume fraction of carbon fiber in the obtained contoured carbon fiber preform is 40%, and the volume fraction of carbon fiber along the Z direction (height direction) is 15%.

[0089] ⑤ is the same as step ⑤ of Example 1.

[0090] ⑥ is the same as step ⑥ of Example 1.

[0091] The present invention conducted performance tests on the heat-conducting ceramic-based composite materials with contoured structures prepared in various embodiments and comparative examples. The test results are shown in Table 1.

[0092] Table 1

[0093]

[0094] In Table 1, the symbol “-” indicates that the performance indicator has not been tested.

[0095] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0096] 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 method for preparing a heat-conducting ceramic-based composite material with a contoured structure, characterized in that: The profiling structure includes a circumferential direction, a wall thickness direction and a height direction, and the preparation method includes the following steps: (1) weaving polyacrylonitrile-based carbon fibers into a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure, and weaving a mixture of polyacrylonitrile-based carbon fibers and mesophase pitch-based carbon fibers into a unidirectional carbon fiber cloth for the height direction of the profiling structure; (2) Laying a unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and a unidirectional carbon fiber cloth for the height direction of the profiling structure on the surface of a forming tool to obtain a cloth layer structure having a preset wall thickness, and performing 2.5D weaving and / or three-dimensional puncture on the cloth layer structure in the wall thickness direction using a fiber bundle composed of a mixture of polyacrylonitrile-based carbon fiber and mesophase pitch-based carbon fiber to obtain a carbon fiber preform of the profiling structure; (3) preparing a carbon interface layer on the fiber surface of the contoured carbon fiber preform by chemical vapor deposition and performing graphitization treatment to obtain a carbon fiber intermediate blank; (4) using a precursor impregnation cracking process to react a ceramic precursor solution with a carbon fiber intermediate body to obtain a thermally conductive ceramic matrix composite material having a profiled structure; the profiled structure is a cylindrical structure, the thermally conductive ceramic matrix composite material has a bending strength of 357 to 360 MPa, and a thermal conductivity in a wall thickness direction of 186 to 190 W / (m·K); in step (4), a ceramic precursor comprising one or more of SiC, HfC, TaC, ZrC, and ZrB2 is used. A ceramic precursor solution is subjected to a precursor impregnation and cracking process; the ceramic precursor solution further contains graphene nanosheets and boron nitride nanosheets; the mass ratio of the ceramic precursor, graphene nanosheets and boron nitride nanosheets in the ceramic precursor solution is (80-90):(8-12):(4-6); the graphene nanosheets have a sheet diameter of 5-10 μm and a thickness of 3-10 nm; the boron nitride nanosheets have a sheet diameter of 1-2 μm and a thickness of 60-120 nm.

2. The preparation method according to claim 1, characterized in that In step (1): The polyacrylonitrile-based carbon fiber is one or more of T300, T700, and T1000; The surface density of the unidirectional carbon fiber cloth used in the circumferential direction of the profiling structure is 200-300g / m 2 ; The thermal conductivity of the mesophase pitch-based carbon fiber after graphitization treatment is not less than 800 W / (m·K); In the unidirectional carbon fiber cloth used in the height direction of the profiling structure, the volume fraction ratio of the mesophase pitch-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1-3):1; and / or The surface density of the unidirectional carbon fiber cloth used in the height direction of the profiling structure is 200-300 g / m 2 .

3. The preparation method according to claim 1, characterized in that In step (2): The plying is performed alternately in the order of 1 layer of unidirectional carbon fiber cloth for the circumferential direction of the profiling structure and 1 to 2 layers of unidirectional carbon fiber cloth for the height direction of the profiling structure; and / or The preset wall thickness is 10 to 20 mm.

4. The preparation method according to claim 1, characterized in that In step (2): In the fiber bundle, the volume fraction ratio of the mesophase pitch-based carbon fiber to the polyacrylonitrile-based carbon fiber is (1-3):1; The specification of the fiber bundle is 2K to 4K; and / or The volume fraction of the carbon fibers in the contoured structural carbon fiber preform is 35-45%, and the volume fraction of the carbon fibers along the height direction is 10-18%.

5. The preparation method according to claim 1, wherein: The thickness of the carbon interface layer is 50 to 200 nm; The temperature of the graphitization treatment is 2800-3200° C., and the time of the graphitization treatment is 15-30 minutes; and / or The forming tool is a cylindrical graphite tool.

6. The preparation method according to claim 1, wherein: The solid content of the ceramic precursor solution is 50% to 70%; In the precursor impregnation pyrolysis process, the pyrolysis temperature is 1400-1700°C and the pyrolysis time is 2-4 hours; and / or The precursor impregnation and cracking are repeated 15 to 20 times.

7. The preparation method according to claim 1, wherein: The ceramic precursor solution is prepared by adding the ceramic precursor, graphene nanosheets and boron nitride nanosheets into a solvent, and then stirring and ultrasonically treating the solvent.

8. A thermally conductive ceramic-based composite material with a contoured structure obtained by the preparation method according to any one of claims 1 to 7.

9. The heat-conducting ceramic-based composite material with a contoured structure according to claim 8, characterized in that: The contoured heat-conducting ceramic matrix composite material has one or more of the following properties: Density is 2.5-3.5g / cm 3 ; The diameter of the outer contour of the cylindrical structure is not less than 300 mm, the height of the cylindrical structure is not less than 300 mm, and the wall thickness of the cylindrical structure is 10 to 20 mm.

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