Three-dimensional hollow carbon fiber composite material and preparation method thereof

Abstract

The invention provides a three-dimensional hollow carbon fiber composite material and a preparation method thereof, and relates to the technical field of aviation-grade conductive materials, and the three-dimensional hollow carbon fiber composite material comprises a three-dimensional hollow carbon fiber woven part and a carbon nanotube functional resin layer, the three-dimensional hollow carbon fiber woven part comprises an upper surface layer, a lower surface layer and a pile warp core column connected between the upper surface layer and the lower surface layer, and the surfaces of the upper surface layer and the lower surface layer are coated with the carbon nano tube functional resin layers respectively. The preparation method comprises the following steps: S1, preparing a three-dimensional hollow carbon fiber woven part; s2, coating carbon nanotube functional resin; s3, RTM liquid glue is poured; and S4, thermocuring and forming. According to the three-dimensional hollow carbon fiber composite material, lap joint of a three-dimensional conductive network is achieved, the conductive performance of the composite material in the fiber direction, the direction perpendicular to the fiber in the laying layer and the thickness direction of the laying layer is improved, the multi-direction conductive performance is improved, and current rapidly flows away in the controllable thickness area of the composite material without damaging the composite material.

Description

Technical Field

[0001] This invention relates to the field of aerospace-grade conductive materials technology, specifically to a three-dimensional hollow carbon fiber composite material and its preparation method. Background Technology

[0002] Carbon fiber, due to its light weight and excellent mechanical properties, has been frequently used in recent years to manufacture carbon fiber structural components for applications in aircraft, high-speed trains, wind power generation, and other technological fields. Currently, commonly used carbon fiber structural components are typically two-dimensional carbon fiber composites impregnated with resin. However, carbon fiber composites have a higher resistivity compared to traditional metal materials; for example, T1000G carbon fiber has a resistivity of 1.4 × 10⁻⁶. -6 The resistivity of most carbon fiber composites is approximately 6 × 10 Ω·m. -5 The resistivity of aluminum is Ω·m, while that of aluminum is only 2.8 × 10⁻⁶. -8 Ω·m. Therefore, when a lightning channel forms between an aircraft or wind turbine blade and a charge source, and a huge amount of electrical energy flows into the spacecraft or wind turbine blade through the conductive path, the carbon fiber composite material, with its high resistivity, will absorb more electrical energy than metal materials when subjected to the same lightning current. This can lead to resistance heat and lightning damage to the carbon fiber composite material, potentially causing catastrophic destruction. The lightning and antistatic properties of carbon fiber composite materials are extremely important in applications such as aircraft, high-speed trains, and wind power generation.

[0003] Existing methods for protecting against lightning strikes and electrostatic damage involve covering the interlayer of carbon fiber structures with metal mesh to conduct internal current. However, this method has the following drawbacks:

[0004] First, it increases the weight of carbon fiber structural components, which contradicts the lightweight design goal and limits the usage scenarios and application areas.

[0005] Secondly, the poor bonding strength between the metal mesh and the resin interface, and the mismatch in their coefficients of thermal expansion, easily lead to the peeling off of the metal mesh.

[0006] Third, it is difficult to lay metal mesh on the geometrically complex parts of carbon fiber structural components, and it is also difficult to integrate the structure and function into a unified form.

[0007] Fourth, the resistivity of the carbon fiber structure is different in the fiber direction and the thickness direction of the layup, with a difference of several orders of magnitude. Even if a metal mesh is laid between the layers, the improvement effect is limited. In particular, the resistivity in the thickness direction of the layup is high, and the multi-directional conductivity is different, so it still cannot effectively improve the lightning protection and antistatic performance.

[0008] Fifth, the resin impregnated on the surface of the two-dimensional carbon fiber composite material contains conductive nanoparticles, which makes it difficult to control the chemical rheology during the liquid injection process and the curing reaction process.

[0009] This invention proposes a three-dimensional hollow carbon fiber composite material and its preparation method. By improving the structure of the carbon fiber composite material and adding a multifunctional layer, the anisotropic conductivity of the carbon fiber composite material is simultaneously improved to meet the requirements of lightning protection and antistatic functions. Summary of the Invention

[0010] (a) Technical problems to be solved

[0011] To address the shortcomings of existing technologies, this invention provides a three-dimensional hollow carbon fiber composite material and its preparation method, which solves the technical problems of poor multidirectional conductivity, especially poor conductivity along the thickness direction, caused by the anisotropy of commonly used carbon fiber structural components; delamination and peeling of structural components due to the laying of metal mesh; difficulty in laying metal mesh for complex geometries; and difficulty in controlling the chemical rheology of resin during the curing process of composite materials due to the mixing of conductive nanofillers in the resin.

[0012] (2) Technical solution

[0013] To achieve the above objectives, the present invention provides the following technical solution:

[0014] A three-dimensional hollow carbon fiber composite material includes a three-dimensional hollow carbon fiber braid and a carbon nanotube functional resin layer. The three-dimensional hollow carbon fiber braid includes an upper layer, a lower layer, and a core column connecting the upper layer and the lower layer. The carbon nanotube functional resin layer is coated on the surfaces of the upper layer and the lower layer respectively.

[0015] Preferably, the upper layer, the lower layer, and the warp core are all woven from carbon fiber warp yarns and carbon fiber weft yarns.

[0016] Preferably, the warp core is formed by interlacing the carbon fiber warp yarns and the carbon fiber weft yarns in a figure-eight spiral.

[0017] Preferably, after the upper layer is woven, the carbon fiber warp and weft yarns continue to be woven continuously into the pile warp core, and then the lower layer is woven continuously, so that the three-dimensional hollow carbon fiber braided parts form an interconnected integral structure.

[0018] Preferably, the upper layer and the lower layer have continuous micropores evenly distributed on them.

[0019] Preferably, the carbon nanotube functional resin layer comprises nickel-plated multi-walled carbon nanotubes and epoxy resin.

[0020] Preferably, the carbon nanotube functional resin layer exhibits a uniform lattice distribution on both the upper and lower layers.

[0021] The preparation method of three-dimensional hollow carbon fiber composite material includes the following steps:

[0022] S1. Preparation of three-dimensional hollow carbon fiber braided parts:

[0023] The upper layer is made by interweaving carbon fiber warp and carbon fiber weft yarns. The extended carbon fiber warp and carbon fiber weft yarns continue to be woven into a figure-eight shaped pile warp core. After the pile warp core is woven, the extended carbon fiber warp and carbon fiber weft yarns continue to be woven into the lower layer.

[0024] S2. Coated carbon nanotube functional resin:

[0025] Pre-processed three-dimensional hollow carbon fiber braided parts;

[0026] Preparation of nickel-plated multi-walled carbon nanotube functional resin;

[0027] Nickel-plated multi-walled carbon nanotube functional resin is coated on the upper and lower layers of a dried three-dimensional hollow carbon fiber braid, so that the nickel-plated multi-walled carbon nanotube functional resin exhibits a uniform lattice distribution on both the upper and lower layers, forming a nickel-plated multi-walled carbon nanotube functional resin layer.

[0028] S3.RTM liquid glue injection:

[0029] The three-dimensional hollow carbon fiber braid coated with a nickel-plated multi-walled carbon nanotube functional resin layer is placed into the molding mold of the RTM infusion equipment, and the pressing height of the molding mold is adjusted.

[0030] The liquid resin is poured into the resin tank of the RTM infusion equipment, and the resin in the tank is degassed.

[0031] Connect the RTM injection equipment to the molding mold, and inject the resin into the molding mold under pressure to complete the liquid glue injection;

[0032] S4. Thermosetting molding:

[0033] The molding mold for injecting liquid resin is heated. After the three-dimensional hollow carbon fiber braid inside the molding mold has cured and cooled to room temperature, the molding mold is opened to obtain a three-dimensional hollow carbon fiber composite material.

[0034] Furthermore, the molding die described in step 3 includes a lower die, an upper die, a limiting block, a glue inlet, and a glue overflow outlet. The specific method for RTM liquid glue injection in step 3 is as follows:

[0035] The three-dimensional hollow carbon fiber braid coated with a nickel-plated multi-walled carbon nanotube functional resin layer is placed on the lower mold. Limiting blocks are set on both sides of the braid. The height of the limiting blocks is set according to the height of the warp core column to adjust the pressing height of the molding mold. The upper mold is closed and locked to seal the upper and lower molds.

[0036] The liquid resin is poured into the resin tank of the RTM infusion equipment, and the resin in the tank is degassed using a vacuum.

[0037] The RTM injection equipment is connected to the molding mold. The resin is pressed into the molding mold from the injection port by applying pressure, and the excess resin is sucked out from the overflow port by the assistance of a vacuum pump, thus completing the liquid resin injection.

[0038] Furthermore, the specific method for preprocessing the three-dimensional hollow carbon fiber braided component in step S2 is as follows:

[0039] The surface of the woven parts is subjected to an ablation treatment at 350℃ for 30 seconds to remove impurities.

[0040] The specific method for preparing the nickel-plated multi-walled carbon nanotube functional resin in step S2 is as follows:

[0041] Based on the amount of nickel-plated multi-walled carbon nanotube functional resin layer to be coated 1 square meter, 0.5 mg of dry polyvinylpyrrolidone powder and 50 ml of liquid epoxy resin were weighed and mixed. The mixture was stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, 0.5 mg of dry nickel-plated multi-walled carbon nanotube powder was weighed and added to the above mixture. The mixture was stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, it was treated under 80 kHz ultrasound for 2 hours to obtain a uniformly mixed conductive functional resin system. Triethylenetetramine was added to the system and stirred evenly for later use.

[0042] (III) Beneficial Effects

[0043] This invention provides a three-dimensional hollow carbon fiber composite material and its preparation method. Compared with the prior art, it has the following advantages:

[0044] 1. The present invention is a carbon fiber composite material with a three-dimensional hollow structure, which realizes the overlap of a three-dimensional conductive network, improves the conductivity of the composite material in the fiber direction, the direction perpendicular to the fiber in the layup, and the thickness direction of the layup, and achieves multi-directional conductivity improvement. Lightning current flows away rapidly in the controllable thickness area of ​​the composite material without damaging the composite material.

[0045] 2. The carbon fiber composite material of the present invention has omnidirectional protection function, eliminating the need to lay metal mesh between layers, thus avoiding defects such as delamination and deformation caused by poor interfacial strength between metal mesh and resin.

[0046] 3. The carbon fiber composite material of the present invention is formed by coating nickel-plated multi-walled carbon nanotube functional resin on the upper and lower surfaces of a three-dimensional hollow carbon fiber braid. The resulting functional resin layer has excellent electrical conductivity, and the current is guided through the functional resin layer to various directions of the braid, thereby improving the multi-directional electrical conductivity.

[0047] 4. In preparing carbon fiber composite materials, the present invention first coats a nickel-plated multi-walled carbon nanotube functional resin, and then performs RTM liquid injection molding. This avoids impregnating the woven fibers with conductive nanoparticles mixed in the injection resin, thereby improving the problem of difficult chemical rheology control of mixed resins during liquid injection and curing, and reducing the difficulty of the liquid injection molding process.

[0048] 5. In the preparation of carbon fiber composite materials, the present invention sets a limiting block on the lower mold according to the height of the warp core column to limit the pressing height of the molding mold, effectively avoiding the expansion and deformation of the warp core column during the pressing process, and improving the overall conductivity of the braided part; coating only the two surfaces of the braided part with nickel-plated multi-walled carbon nanotube functional resin also helps to reduce production costs. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the structure of the three-dimensional hollow carbon fiber braided component in an embodiment of the present invention;

[0051] Figure 2 This is a schematic diagram of the molding die in an embodiment of the present invention;

[0052] Figure 3 This is a schematic diagram of the structure after the woven part is placed into the forming mold in an embodiment of the present invention.

[0053] Among them, 1. upper layer; 2. warp core column; 3. lower layer; 4. lower mold; 5. upper mold; 6. limiting block; 7. overflow port; 8. glue inlet; 9. three-dimensional hollow carbon fiber braided part coated with carbon nanotube functional resin. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] This application provides a three-dimensional hollow carbon fiber composite material and its preparation method, which solves the technical problems of poor multidirectional conductivity caused by the anisotropy of commonly used carbon fiber structural parts, especially poor conductivity along the thickness direction; delamination of structural parts caused by laying metal mesh; difficulty in laying metal mesh for complex geometries; and difficulty in controlling the chemical rheology of resin during the curing process of composite materials due to the mixing of conductive nanofillers in the resin.

[0056] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0057] Example 1:

[0058] like Figure 1 As shown, the three-dimensional hollow carbon fiber composite material includes a three-dimensional hollow carbon fiber braid and a carbon nanotube functional resin layer.

[0059] The three-dimensional hollow carbon fiber braided component includes an upper layer 1, a lower layer 3, and a core post 2 connecting the upper layer 1 and the lower layer 3.

[0060] The upper layer 1, the lower layer 3, and the pile warp core 2 are all woven from carbon fiber warp yarns and carbon fiber weft yarns. The carbon fiber warp yarns and carbon fiber weft yarns of the upper layer 1 are continuously woven into the pile warp core 2 before the lower layer 3 is woven, so that the three-dimensional hollow carbon fiber woven part forms an interconnected integral structure.

[0061] There are multiple warp cores 2, which are arranged in an array. Each warp core 2 is in the shape of an 8 and is made of carbon fiber warp yarns and carbon fiber weft yarns interwoven in a spiral.

[0062] Carbon nanotube functional resin layers are coated on the surfaces of the upper layer 1 and the lower layer 3, respectively, and exhibit a uniform dot matrix distribution on both the upper layer 1 and the lower layer 3.

[0063] Example 2:

[0064] The preparation of three-dimensional hollow carbon fiber composite materials requires the use of RTM injection equipment. The RTM injection equipment mainly uses a closed-mold process to inject liquid resin into the molding mold of the three-dimensional hollow carbon fiber composite material to achieve the preparation of the three-dimensional hollow carbon fiber composite material.

[0065] This invention improves the molding die for the preparation of three-dimensional hollow carbon fiber composite materials, such as... Figure 1 , Figure 2 As shown, the molding die includes a lower die 4, an upper die 5, a limiting block 6, an overflow port 7, and a glue inlet 8. Due to the presence of the three-dimensional hollow carbon fiber core 2, a limiting block 6 is added to the molding die. The thickness of the limiting block 6 is adaptively adjusted according to the height of the hollow carbon fiber core 2, providing a compression space between the upper die 5 and the lower die 4 that can accommodate the height of the hollow carbon fiber core 2. This is because the hollow carbon fiber core 2 is prone to expansion and deformation during compression. By controlling the compression height, the deformation problem of the hollow carbon fiber core 2 during compression can be effectively improved, thereby ensuring the stability of the three-dimensional hollow carbon fiber composite material.

[0066] Example 3:

[0067] The preparation method of three-dimensional hollow carbon fiber composite material includes the following steps:

[0068] S1. Preparation of three-dimensional hollow carbon fiber braided parts:

[0069] The upper layer is made by interweaving carbon fiber warp and weft yarns. The extended carbon fiber warp and weft yarns continue to be woven into a figure-eight shaped pile warp core. After the pile warp core is woven, the extended carbon fiber warp and weft yarns continue to be woven into the lower layer.

[0070] S2. Coated carbon nanotube functional resin:

[0071] Pre-processed three-dimensional hollow carbon fiber braided parts:

[0072] The surface of the woven parts is subjected to an ablation treatment at 350℃ for 30 seconds to remove impurities.

[0073] Preparation of nickel-plated multi-walled carbon nanotube functional resin:

[0074] Based on the amount of nickel-plated multi-walled carbon nanotube functional resin layer to be coated 1 square meter, 0.5 mg of dry polyvinylpyrrolidone powder and 50 ml of liquid epoxy resin were weighed and mixed, and stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, 0.5 mg of dry nickel-plated multi-walled carbon nanotube powder was weighed and added to the above mixture, and stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, the mixture was treated under 80 kHz ultrasound for 2 hours to obtain a uniformly mixed conductive functional resin system. Triethylenetetramine was added to the system and stirred evenly for later use.

[0075] Coating:

[0076] Nickel-plated multi-walled carbon nanotube functional resin is coated on the upper and lower layers of a dried three-dimensional hollow carbon fiber braid. The nickel-plated multi-walled carbon nanotube functional resin is uniformly distributed in the upper and lower layers to form a nickel-plated multi-walled carbon nanotube functional resin layer.

[0077] S3.RTM liquid glue injection:

[0078] like Figure 3 As shown, a three-dimensional hollow carbon fiber braid 9 coated with carbon nanotube functional resin is placed on the lower mold 4 of the RTM infusion device. Limiting blocks 6 are set on both sides of the braid 9. The height of the limiting blocks 6 is set according to the height of the warp core column 2 to adjust the pressing height of the molding mold. The upper mold 5 is closed and locked to seal the upper mold 5 and the lower mold 4.

[0079] The liquid resin is poured into the resin tank of the RTM infusion equipment, and the resin in the tank is degassed using a vacuum.

[0080] Connect the RTM injection equipment to the molding mold, pressurize the resin from the injection port 8 into the molding mold, and use a vacuum pump to help suck out the excess resin from the overflow port 7 to complete the liquid resin injection.

[0081] S4. Thermosetting molding:

[0082] The molding mold for injecting liquid resin is heated. After the three-dimensional hollow carbon fiber braid inside the molding mold is cured and cooled to room temperature, the molding mold is opened to obtain a three-dimensional hollow carbon fiber composite material with an inverted trapezoidal structure.

[0083] The three-dimensional hollow carbon fiber composite material prepared by the above method has an electrical conductivity of approximately 10 along the fabric surface direction. 6 The conductivity along the fabric thickness direction can reach 10 S / m. 4 S / m.

[0084] Comparative Example 1 differs from Examples 1-3 in that:

[0085] Three-dimensional hollow carbon fiber composite materials include three-dimensional hollow carbon fiber braided parts, without coating the upper and lower layers with nickel-plated multi-walled carbon nanotube functional resin. The three-dimensional hollow carbon fiber braided parts are directly cured and molded after RTM liquid injection.

[0086] The electrical conductivity of this three-dimensional hollow carbon fiber composite material along the thickness direction of the fabric is 10. 3 S / m rating.

[0087] Comparative Example 2 differs from Examples 1-3 in that:

[0088] Using existing two-dimensional carbon fiber structural components as a comparative example, the two-dimensional carbon fiber structural components were directly subjected to RTM liquid injection and then cured.

[0089] The surface conductivity of this two-dimensional carbon fiber structural component is 10. 3 The S / m rating indicates good conductivity along the fabric surface direction, but low conductivity along the fabric thickness direction.

[0090] In summary, compared with existing technologies, it has the following beneficial effects:

[0091] 1. The present invention is a carbon fiber composite material with a three-dimensional hollow structure, which realizes the overlap of a three-dimensional conductive network, improves the conductivity of the composite material in the fiber direction, the direction perpendicular to the fiber in the layup, and the thickness direction of the layup, and achieves multi-directional conductivity improvement. Lightning current flows away rapidly in the controllable thickness area of ​​the composite material without damaging the composite material.

[0092] 2. The carbon fiber composite material of the present invention has omnidirectional protection function, eliminating the need to lay metal mesh between layers, thus avoiding defects such as delamination and deformation caused by poor interfacial strength between metal mesh and resin.

[0093] 3. The carbon fiber composite material of the present invention is formed by coating nickel-plated multi-walled carbon nanotube functional resin on the upper and lower surfaces of a three-dimensional hollow carbon fiber braid. The resulting functional resin layer has excellent electrical conductivity, and the current is guided through the functional resin layer to various directions of the braid, thereby improving the multi-directional electrical conductivity.

[0094] 4. In preparing carbon fiber composite materials, the present invention first coats a nickel-plated multi-walled carbon nanotube functional resin, and then performs RTM liquid injection molding. This avoids impregnating the woven fibers with conductive nanoparticles mixed in the injection resin, thereby improving the problem of difficult chemical rheology control of mixed resins during liquid injection and curing, and reducing the difficulty of the liquid injection molding process.

[0095] 5. In the preparation of carbon fiber composite materials, the present invention sets a limiting block on the lower mold according to the height of the warp core column to limit the pressing height of the molding mold, effectively avoiding the expansion and deformation of the warp core column during the pressing process, and improving the overall conductivity of the braided part; coating only the two surfaces of the braided part with nickel-plated multi-walled carbon nanotube functional resin also helps to reduce production costs.

[0096] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A three-dimensional hollow carbon fiber composite material, characterized in that, The invention includes a three-dimensional hollow carbon fiber braid and a carbon nanotube functional resin layer. The three-dimensional hollow carbon fiber braid includes an upper layer, a lower layer, and a core column connecting the upper layer and the lower layer. The carbon nanotube functional resin layer is coated on the surfaces of the upper layer and the lower layer respectively.

2. The three-dimensional hollow carbon fiber composite material as described in claim 1, characterized in that, The upper layer, the lower layer, and the core column are all made of interwoven carbon fiber warp yarns and carbon fiber weft yarns.

3. The three-dimensional hollow carbon fiber composite material as described in claim 2, characterized in that, The core column is formed by interlacing the carbon fiber warp yarns and the carbon fiber weft yarns in a figure-eight spiral.

4. The three-dimensional hollow carbon fiber composite material as described in claim 2, characterized in that, After the upper layer is woven, the carbon fiber warp and weft yarns continue to weave the pile warp core, and then continue to weave the lower layer, so that the three-dimensional hollow carbon fiber braided parts form an interconnected integral structure.

5. The three-dimensional hollow carbon fiber composite material as described in claim 1, characterized in that, The upper layer and the lower layer have continuous micropores evenly distributed on them.

6. The three-dimensional hollow carbon fiber composite material as described in claim 1, characterized in that, The carbon nanotube functional resin layer comprises nickel-plated multi-walled carbon nanotubes and epoxy resin.

7. The three-dimensional hollow carbon fiber composite material as described in claim 6, characterized in that, The carbon nanotube functional resin layer exhibits a uniform lattice distribution on both the upper and lower layers.

8. The method for preparing the three-dimensional hollow carbon fiber composite material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of three-dimensional hollow carbon fiber braided parts: The upper layer is made by interweaving carbon fiber warp and carbon fiber weft yarns. The extended carbon fiber warp and carbon fiber weft yarns continue to be woven into a figure-eight shaped pile warp core. After the pile warp core is woven, the extended carbon fiber warp and carbon fiber weft yarns continue to be woven into the lower layer. S2. Coated carbon nanotube functional resin: Pre-processed three-dimensional hollow carbon fiber braided parts; Preparation of nickel-plated multi-walled carbon nanotube functional resin; Nickel-plated multi-walled carbon nanotube functional resin is coated on the upper and lower layers of a dried three-dimensional hollow carbon fiber braid, so that the nickel-plated multi-walled carbon nanotube functional resin exhibits a uniform lattice distribution on both the upper and lower layers, forming a nickel-plated multi-walled carbon nanotube functional resin layer. S3.RTM liquid glue injection: The three-dimensional hollow carbon fiber braid coated with a nickel-plated multi-walled carbon nanotube functional resin layer is placed into the molding mold of the RTM infusion equipment, and the pressing height of the molding mold is adjusted. The liquid resin is poured into the resin tank of the RTM infusion equipment, and the resin in the tank is degassed. Connect the RTM injection equipment to the molding mold, and inject the resin into the molding mold under pressure to complete the liquid glue injection; S4. Thermosetting molding: The molding mold for injecting liquid resin is heated. After the three-dimensional hollow carbon fiber braid inside the molding mold has cured and cooled to room temperature, the molding mold is opened to obtain a three-dimensional hollow carbon fiber composite material.

9. The method for preparing the three-dimensional hollow carbon fiber composite material as described in claim 8, characterized in that, The molding die mentioned in step 3 includes a lower die, an upper die, a limiting block, a glue inlet, and a glue overflow outlet. The specific method for RTM liquid glue injection in step 3 is as follows: The three-dimensional hollow carbon fiber braid coated with a nickel-plated multi-walled carbon nanotube functional resin layer is placed on the lower mold. Limiting blocks are set on both sides of the braid. The height of the limiting blocks is set according to the height of the warp core column to adjust the pressing height of the molding mold. The upper mold is closed and locked to seal the upper and lower molds. The liquid resin is poured into the resin tank of the RTM infusion equipment, and the resin in the tank is degassed using a vacuum. The RTM injection equipment is connected to the molding mold. The resin is pressed into the molding mold from the injection port by applying pressure, and the excess resin is sucked out from the overflow port by the assistance of a vacuum pump, thus completing the liquid resin injection.

10. The method for preparing the three-dimensional hollow carbon fiber composite material as described in claim 8, characterized in that, The specific method for preprocessing the three-dimensional hollow carbon fiber braided parts in step S2 is as follows: The surface of the woven parts is subjected to an ablation treatment at 350℃ for 30 seconds to remove impurities. The specific method for preparing the nickel-plated multi-walled carbon nanotube functional resin in step S2 is as follows: Based on the amount of nickel-plated multi-walled carbon nanotube functional resin layer to be coated 1 square meter, 0.5 mg of dry polyvinylpyrrolidone powder and 50 ml of liquid epoxy resin were weighed and mixed. The mixture was stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, 0.5 mg of dry nickel-plated multi-walled carbon nanotube powder was weighed and added to the above mixture. The mixture was stirred in a water bath at a constant temperature of 75°C for 1 hour. Then, it was treated under 80 kHz ultrasound for 2 hours to obtain a uniformly mixed conductive functional resin system. Triethylenetetramine was added to the system and stirred evenly for later use.

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