A method of manufacturing a carbon-carbon composite spiral vane shaft

Abstract

The application discloses a method for manufacturing carbon-carbon composite spiral blade rod, and belongs to the technical field of high-performance carbon-carbon composite material preparation, which comprises the following steps: preparing a carbon fiber preform as an inner mold; performing first densification treatment on the inner mold; performing chemical activation and interface construction treatment on the surface of the first densification treated inner mold; performing carbon fiber winding on the surface of the treated inner mold to form an outer winding structure, and introducing resin in the winding process; repeatedly performing the step b on the component with the outer winding structure to perform densification treatment, and finally performing mechanical processing to obtain the carbon-carbon composite spiral blade rod; the method overcomes the shortcomings of the existing single structure technology, especially solves the problems of weak interface combination, uneven densification and difficult compatibility of axial performance and radial performance of the super-long rod when the needle-punched structure and the winding structure are combined, and thus a high-performance product with high interface combination strength and high density uniformity is manufactured.

Description

Technical Field

[0001] This invention belongs to the field of high-performance carbon-carbon composite material preparation technology, specifically a method for manufacturing carbon-carbon composite material helical blade rods. Background Technology

[0002] Carbon-carbon composite rotor blades are key components of high-performance rotor systems, playing an irreplaceable role in aerospace, high-end unmanned aerial vehicles (UAVs), and other fields due to their lightweight, high specific strength, high specific modulus, and excellent high-temperature mechanical properties. Their performance directly determines the rotor's propulsion efficiency, vibration and noise levels, and service reliability.

[0003] Currently, the mainstream technical approaches for manufacturing such long rod-shaped carbon-carbon composite materials are mainly divided into two categories: The first type is the integral needle-punched structure. This method first needle-punches carbon cloth layers and a mesh to form a two-and-a-half-dimensional (2.5D) preform, and then densifies it through chemical vapor infiltration and other means. The advantage of this method is that the preform structure has good overall integrity and excellent interlayer performance, and it can manufacture components with complex shapes. However, its inherent defects are also very obvious: First, the fiber continuity along the axial direction (length direction) of the needle-punched structure is insufficient, resulting in low axial tensile and flexural moduli, making it difficult to meet the stringent requirements for high stiffness of blade rods; second, for ultra-long rods (e.g., several meters long), the reactive gas is difficult to penetrate evenly into the core of the preform during chemical vapor infiltration, resulting in significant density gradients along the length and radial directions of the component, poor performance uniformity, and low yield.

[0004] The second type is the fiber-wound structure. This method involves winding continuous carbon fiber yarn onto a mandrel, followed by resin impregnation, curing, and carbonization. This approach fully utilizes the axial high performance of continuous fibers, achieving extremely high axial strength and modulus. However, this method also faces significant challenges: on the one hand, when the wound structure is used as an independent component, its radial properties and interlaminar shear strength are poor, making it prone to delamination failure under complex alternating loads; on the other hand, when using the wound structure as a matrix for subsequent chemical vapor infiltration densification, the dense surface layer severely hinders the diffusion of reactive gases into the interior, resulting in an extremely long densification cycle, low efficiency, and difficulty in achieving internal densification, thus limiting the final overall performance of the component. Furthermore, the internal mold tooling required for manufacturing hollow long rods and capable of withstanding subsequent high-temperature treatments is costly and complex to operate.

[0005] Existing technologies, whether using a single needle-punched structure or a single winding structure, cannot simultaneously achieve high axial stiffness and strength while also possessing good interlaminar properties, high densification efficiency, and excellent density uniformity. The advantages of these two elements cannot be simply combined. The core bottleneck lies in how to establish a robust and durable interface between the needle-punched and winding structures that can withstand subsequent high-temperature treatments and extreme service loads. Without effective interface bonding technology, simple physical composites not only fail to achieve performance enhancement but may also lead to premature component failure due to interface delamination. Summary of the Invention

[0006] To address the above problems, this invention provides a method for manufacturing carbon-carbon composite spiral blade rods, overcoming the shortcomings of existing single-structure technologies. In particular, it solves the problems of weak interfacial bonding, uneven densitying, and difficulty in balancing the axial and radial properties of ultra-long rods when combining needle-punched and wound structures, thereby producing high-performance products with high interfacial bonding strength and high density uniformity.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for manufacturing a carbon-carbon composite helical blade rod includes the following steps: a. Fabricate a carbon fiber preform as an inner mold, wherein the carbon fiber preform has a 2.5D needle-punched structure; b. Perform an initial densification treatment on the inner mold to achieve a density of 1.0-1.6 g / cm³; c. Chemical activation and interface construction treatment of the inner mold surface after the first densification; d. Carbon fiber is wound onto the treated inner mold surface to form an outer winding structure, and resin is introduced during the winding process; e. Repeat step b for the densification treatment of the component with the outer winding structure, and finally process it by machining to obtain the carbon-carbon composite spiral blade rod; Step c, the chemical activation and interface construction treatment, includes: (1) The surface of the inner mold is subjected to plasma treatment with fluorine-containing gas to introduce fluorine elements and form nanoscale roughness; (2) A dispersion containing rare earth silicate nanoparticles and zeolite imidazole ester framework material was coated onto the surface of the plasma-treated inner mold. (3) Grafting treatment of the coated surface is performed using amino-functionalized ionic liquid.

[0008] In this technical solution, step c increases the surface area and activity through physical etching and chemical modification, then achieves mechanical interlocking and stress transfer through a nano-intermediate layer, and finally achieves strong chemical bonding through molecular bridging, thereby constructing a robust, gradient transition interface region between the inner and outer layers.

[0009] In a preferred embodiment, the carbon fiber preform in step a is formed by integral carbon cloth lay-up / mesh needle punching composite, followed by radial continuous winding and needle punching, with a carbon cloth content of 80±10%, a mesh content of 20±10%, and a length of 1-5m.

[0010] In a preferred embodiment, the densification process in step b is as follows: the inner mold is cured at 150-300℃ for 2-20 hours, then subjected to vapor deposition to densify to 0.7-1.6 g / cm³ at a deposition temperature of 800-1300℃, followed by high-temperature treatment at 1800-2800℃ for 2-20 hours, and finally impregnated and carbonized for densification at an impregnation pressure of 0.5-50 MPa and a carbonization temperature of 600-1000℃; the deposition raw material is one of natural gas, propylene, and propane.

[0011] In a preferred embodiment, the fluorine-containing gas in step c(1) is sulfur hexafluoride or carbon tetrafluoride, the plasma treatment power is 100-1000W, and the treatment time is 1-30min. This technical solution is a synergistic effect of plasma physicochemical processes. Physical effect: In the plasma field, accelerated ions and electrons bombard the carbon fiber surface at high speed, like "micro-sandblasting," stripping away the weak boundary layer and amorphous carbon on the surface through the sputtering effect, forming nanoscale grooves and protrusions, increasing the specific surface area and roughness. Chemical effect: High-energy plasma causes CF4 or SF6 molecules to dissociate, generating active fluorine radicals (F•). These fluorine radicals react with carbon atoms on the carbon fiber surface to form strongly polar CF covalent bonds, significantly improving the chemical energy and wettability of the fiber surface.

[0012] In a preferred embodiment, the rare earth silicate in step c(2) is selected from at least one of lutetium yttrium silicate and erbium yttrium silicate, with a particle size of 10-200 nm. This technical solution utilizes the rigid support and pinning effect of nanoparticles. These high-hardness, high-thermal-stability nanoparticles are dispersed in the interface layer. When the interface is subjected to shear stress, they can effectively hinder the propagation path of microcracks (crack deflection and pinning), consuming more fracture energy. Simultaneously, as hard points, they directly bear and transmit part of the load, improving the overall load-bearing capacity of the interface layer.

[0013] In a preferred embodiment, the zeolite imidazole ester framework material in step c(2) is ZIF-8, with a particle size of 50-500 nm. This technical solution is used in the coating and winding stages. The pores of ZIF-8 adsorb resin monomers or oligomers. During the curing and carbonization process, the adsorbed resin is transformed within the confined space, resulting in a tighter bond with the ZIF-8 particles. Finally, at high temperature, ZIF-8 itself is transformed into active nano-carbon, which is dispersed in the interface region, achieving reinforcement from physical adsorption to chemical bonding.

[0014] In a preferred embodiment, the dispersion preparation process is as follows: rare earth silicate nanoparticles and zeolite imidazole ester framework material are mixed in a certain proportion, dispersed in anhydrous ethanol, 5% of the total mass of dispersant polyvinylpyrrolidone is added, and then placed in an ultrasonic cell disruptor and ultrasonically treated for 30 minutes to form a milky white dispersion. The mass ratio of the rare earth silicate nanoparticles to the zeolite imidazole ester framework material is 1-10:10-1.

[0015] In a preferred embodiment, the amino-functionalized ionic liquid in step c(3) is 1-aminopropyl-3-methylimidazolium tetrafluoroborate. The grafting process is as follows: first, prepare an ethanol solution of 1-aminopropyl-3-methylimidazolium tetrafluoroborate with a concentration of 5-10 wt%. Then, immerse the inner mold in the solution. Next, transfer the immersion system to a reaction vessel. Under nitrogen protection, heat the mixture to 80-90°C and stir magnetically for 4-6 hours. Remove the inner mold, rinse it repeatedly with anhydrous ethanol three times, and finally dry it to complete the grafting process. The principle of this technical solution is molecular bridging and covalent bonding. The 1-aminopropyl-3-methylimidazolium tetrafluoroborate molecule is like a "molecular bridge". The amino group (-NH2) at one end of the molecule undergoes a dehydration condensation reaction with the carboxyl group or hydroxyl group on the carbon fiber / coating surface to form a covalent bond. Meanwhile, the imidazole ring cation and tetrafluoroborate anion structures at the other end of the molecule, as well as the long-chain alkanes, exhibit good physical and chemical compatibility with the subsequent resin matrix. In this way, it establishes a strong "chemical anchor" between the inorganic / carbonaceous substrate and the organic resin.

[0016] In a preferred embodiment, the resin in step d is one of epoxy resin, phenolic resin, or furfuryl ketone resin. During the winding process, the resin acts as a binder to fix the fiber position and impregnates the fiber bundle. Subsequently, during the curing stage, the resin undergoes a cross-linking reaction to form an infusible and insoluble three-dimensional network structure, firmly bonding the fibers together. In the subsequent carbonization / densification process, the resin decomposes at high temperature, non-carbon elements escape in the form of small molecules, and the remaining carbon atoms rearrange to form glassy carbon with a disordered layer graphite structure, thereby ultimately transforming the carbon fiber winding layer into a carbon-carbon composite material.

[0017] In a preferred embodiment, the interfacial shear strength between the internal needle-punched structure and the external winding structure of the helical blade rod is not less than 25 MPa, and the coefficient of variation of the density uniformity of the helical blade rod in the length direction is not greater than 5%.

[0018] Compared with the prior art, the technical effects of the present invention are: (1) The present invention fundamentally solves the problem of weak interface bonding and easy delamination caused by the difference in physical and chemical properties between the internal needle-punched structure and the external winding structure through the interface construction treatment in step c; achieves complementary performance advantages, successfully combines the high damage tolerance and good interlayer performance of the internal 2.5D needle-punched structure with the high axial strength advantage of the external winding structure to manufacture a spiral blade rod with excellent comprehensive mechanical properties; optimizes the manufacturing process, adopts the process of "preparing and initially densifying separately, then interface treatment, then composite and finally densifying", decomposes the manufacturing of complex thick-walled components into the processing of multiple thin-walled components, effectively solving the industry pain points of difficulty in one-time molding and uneven densification of ultra-long and complex components; This invention provides the main skeleton through an integral carbon cloth layup, reinforces the interlayer bonding with a mesh, and then forms a stable precast body with fiber reinforcement in all three-dimensional space, complete structure, and no layering through radial winding and needle punching. The content range of carbon cloth and mesh is clearly defined, ensuring that the precast body has initial properties with high strength as the main component (contributed by carbon cloth), while also taking into account a certain degree of toughness and permeability (contributed by mesh), laying a predictable foundation for subsequent densification. This invention utilizes a combination of "low-temperature curing + medium-temperature CVD" processes to efficiently deposit pyrolytic carbon into porous preforms, increasing their density to 0.7-1.6 g / cm³, thus achieving sufficient strength and integrity required for use as an inner mold. The specified natural gas, propylene, and propane are all mature and efficient CVD carbon sources with high pyrolysis efficiency and dense deposited carbon structures, meeting the requirements of high-performance C / C composite materials. This invention utilizes fluorine-containing gas plasma to simultaneously achieve physical bombardment (etching) and chemical grafting (introduction of fluorine) of the carbon fiber surface, completing activation and roughening in one step. The selected rare-earth silicate is an excellent high-temperature ceramic material, which remains stable during subsequent high-temperature treatments up to 2800℃, ensuring the integrity of the interface layer under extreme conditions. ZIF-8 has a regular microporous structure and high specific surface area, which can adsorb subsequent resin precursors and ionic liquids like a "nano-sponge," forming a tight physical bond and material reserve. In subsequent high-temperature treatment, the ZIF-8 framework can be transformed into nitrogen-rich nano-carbon materials. This carbon has high activity and can form stronger chemical connections with the surrounding carbon matrix, acting as a "carbon bridge." The amino groups (-NH2) in the amino-functionalized ionic liquid used interact with the functional groups (such as -COOH) on the surface of the carbon fiber and coating particles activated in the first two steps. The -OH groups react fully to form strong amide or covalent bonds. The ionic liquid itself has a certain degree of flexibility, and its grafted layer can form a stress buffer layer between the hard nanoparticle coating and the subsequent resin, alleviating the internal stress caused by the mismatch of thermal expansion coefficients and improving the toughness of the interface. The above three steps constitute a precise system with interlocking and complementary functions. Their synergistic effect is as follows: The first step is "roughening and activation". Through plasma treatment, the smooth and inert carbon fiber surface is roughened and chemically active, providing a foundation for subsequent steps that can "hold and react". The second step is "building a reinforcing skeleton". The coated nanoparticles (high-temperature resistant rare earth silicates and porous ZIF-8) are like "steel bars and porous bricks", embedded in the roughened substrate of the previous step, forming a strong transition layer with a large surface area. The third step is "molecular bridging and soft connection". The ionic liquid acts as a "smart glue", firmly holding the skeleton built in the second step through chemical bonds on one end, while being compatible with the subsequent resin matrix on the other end. Its flexible long chains can also buffer stress and prevent brittle cracking of the interface. These three steps are indispensable. Without the first step, the coating is prone to peeling off; without the second step, the interface lacks high-temperature strength and sufficient reaction sites; without the third step, the bonding force relies solely on physical action, resulting in insufficient strength and brittleness. The three work together to achieve multiple strengthening effects, from "physical anchoring" to "chemical bonding," and from "rigid connection" to "flexible buffering," jointly creating a high-strength, high-durability interface far exceeding 25 MPa. The epoxy resin, phenolic resin, and furfuryl ketone resin selected in this invention are all resins with high carbon residue. After carbonization, they can form dense glassy carbon, providing a solid carbon matrix for the outer winding structure. These resins have suitable viscosity, which facilitates fiber wetting during the winding process. Their curing temperature is compatible with the previous process, and their carbonization behavior is relatively controllable, which is beneficial for obtaining high-performance C / C composite materials. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solution, the present invention will be described in detail below with reference to embodiments. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0020] Example 1: A method for manufacturing a carbon-carbon composite helical blade rod, comprising the following steps: Step a, making the inner mold: The integral T300 carbon fiber cloth layup and chopped fiber mesh are needle-punched composite, with the carbon cloth content being 80% and the mesh content being 20%. Then, it is radially continuously wound and needle-punched again to form a 2.5D needle-punched carbon fiber preform with a length of 2m, an outer diameter of 85mm, and an inner diameter of 55mm, which serves as the inner mold. Step b, initial encryption: The inner mold was placed in a curing oven and cured at 250°C for 8 hours. Then it was transferred to a CVD oven, where propylene was used as the carbon source and argon was used as the carrier gas. It was then subjected to vapor deposition at 1150°C for 50 hours to increase density. After that, it was subjected to high temperature at 2800°C for 15 hours. Finally, it was impregnated and carbonized to increase density. The impregnation pressure was 10 MPa and the carbonization temperature was 1000°C until the density of the inner mold reached 1.35 g / cm³. Step c, Interface construction processing: Plasma treatment: The densified inner mold was placed in a radio frequency inductively coupled vacuum plasma device, and a CF4 / Ar mixed gas (volume ratio 20 / 80) was introduced and treated for 10 min at a pressure of 50 Pa and a power of 500 W. Nanocomposite coating: 50 nm lutetium yttrium silicate and 100 nm ZIF-8 were mixed at a mass ratio of 1:3, dispersed in anhydrous ethanol, 5% PVP dispersant was added, and ultrasonic treatment was performed for 30 min to form a milky white dispersion; this was coated on the surface of the treated inner mold and dried at 80 °C for 2 h. Ionic liquid grafting: The inner mold was immersed in a 5 wt% 1-aminopropyl-3-methylimidazolium tetrafluoroborate ethanol solution, and stirred at 85°C for 5 h under nitrogen protection. After removal, it was rinsed with ethanol 3 times and dried under vacuum at 60°C. Step d, outer layer winding: Phenolic resin was brushed onto the surface of the treated inner mold, and then T800 grade carbon fiber filaments were used to wind circumferentially on a fiber winding machine at a cross angle of ±45°, controlling the thickness of the blade root to be 15mm thicker than the tube body. Step e, secondary densification and processing: The wound component was placed in a CVD furnace again and subjected to secondary vapor deposition densification at 1100℃ for 80 hours. Then, it was subjected to high-temperature graphitization treatment at 2200℃ for 10 hours. Finally, it was machined to the design dimensions by CNC machine tools to obtain the finished carbon-carbon composite spiral blade rod.

[0021] Example 2 (Preparation of an ultra-long blade rod): A method for manufacturing a carbon-carbon composite helical blade rod includes the following steps: Step a, Making and connecting the inner mold: Three carbon fiber preforms, each 1.8 meters long (same structure as in Example 1), were fabricated. Each preform was individually densified to a density of 1.30 g / cm³ according to step b of Example 1, and its ends were machined. A solid, slender C / C rod with a diameter of 3mm and a threaded surface is used as a connector. Corresponding internal threads are machined at the end of each precast section. The connector is screwed into the first precast section, and then the second and third precast sections are connected in series and tightened to form a continuous rod with a total length of about 5.4 meters. Step c, Interface construction processing: For this connected ultra-long inner mold, the same step c as in Example 1 is used to carry out a comprehensive interface construction process. During plasma treatment, the workpiece is rotated at a constant speed to ensure uniform processing. Step d, outer layer winding: Using the connected and processed ultra-long inner mold as the core mold, continuous and uninterrupted winding is carried out on a large horizontal winding machine using T800 carbon fiber and phenolic resin. Step e, secondary densification and processing: The subsequent secondary densification, high-temperature treatment and machining steps are the same as in Example 1, and finally an ultra-long spiral blade rod with a length of 5.4 meters is obtained.

[0022] Example 3: The main difference between this example and Example 1 lies in the selection of materials for interface construction: In step c(2), yttrium erbium silicate nanoparticles and ZIF-8 are used in a mass ratio of 2:1.

[0023] In step c(3), the grafting reaction temperature is adjusted to 90℃ and the reaction time is 4h.

[0024] In step d, the resin used is furfuryl ketone resin.

[0025] The remaining steps and parameters are consistent with those in Example 1.

[0026] Comparative Example 1: The difference between this comparative example and Example 1 is that step c (interface construction processing) is completely omitted, and after the initial densification in step b, the outer layer winding in step d is performed directly.

[0027] Comparative Example 2: The difference between this comparative example and Example 1 is that only (1) plasma treatment is performed in step c, and (2) nanocomposite coating and (3) ionic liquid grafting are omitted. The plasma treatment parameters are exactly the same as those in Example 1.

[0028] Comparative Example 3: This comparative example aims to compare the manufacturing methods of ultra-long rods: A single 5.4-meter-long integral carbon fiber preform (without segments) was prepared in one go, and then the first CVD densification was carried out directly. Due to the extra-long length of the preform, an extra-large CVD furnace had to be used for densification under the same process parameters (1150℃, 50h). The remaining operations were the same as in Example 1.

[0029] The finished products prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, such as interfacial shear strength test (referring to ASTM D2344 "Standard Method for Testing Strength of Short Beams of Polymer-Based Composite Materials"), density uniformity test (referring to GB / T2997 "Test Methods for Bulk Density, Apparent Porosity and True Porosity of Dense Shaped Refractories"), and three-point bending test (referring to ASTM D7264 "Standard Test Methods for Bending Properties of Polymer-Based Composite Materials"). The test results are shown in the table below.

[0030] Table 1

[0031] It should be noted that, in this document, the terms "comprising," "including," and any other variations 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. Specific examples have been used in this document to illustrate the principles and implementation methods of the present invention. These examples are merely for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be pointed out that, due to the limitations of written expression and the objective existence of infinite specific structures, those skilled in the art can make several improvements, modifications, or variations without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, variations, or combinations, or the direct application of the concept and technical solution of the present invention to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A method for manufacturing a carbon-carbon composite spiral blade rod, characterized in that, Includes the following steps: a. Fabricate a carbon fiber preform as an inner mold, wherein the carbon fiber preform has a 2.5D needle-punched structure; b. Perform an initial densification treatment on the inner mold to achieve a density of 1.0-1.6 g / cm³; c. Chemical activation and interface construction treatment of the inner mold surface after the first densification; d. Carbon fiber is wound onto the treated inner mold surface to form an outer winding structure, and resin is introduced during the winding process; e. Repeat step b for the densification treatment of the component with the outer winding structure, and finally process it by machining to obtain the carbon-carbon composite spiral blade rod; Step c, the chemical activation and interface construction treatment, includes: (1) The surface of the inner mold is subjected to plasma treatment with fluorine-containing gas to introduce fluorine elements and form nanoscale roughness; (2) A dispersion containing rare earth silicate nanoparticles and zeolite imidazole ester framework material was coated onto the surface of the plasma-treated inner mold. (3) Grafting treatment of the coated surface is performed using amino-functionalized ionic liquid.

2. The method according to claim 1, characterized in that, In step a, the carbon fiber preform is made by integral carbon cloth lay-up / mesh needle punching composite, followed by radial continuous winding and needle punching. The carbon cloth content is 80±10%, the mesh content is 20±10%, and the length is 1-5m.

3. The method according to claim 1, characterized in that, The densification process in step b is as follows: the inner mold is cured at 150-300℃ for 2-20 hours, then subjected to vapor deposition to densify to 0.7-1.6 g / cm³ at a deposition temperature of 800-1300℃, followed by high-temperature treatment at 1800-2800℃ for 2-20 hours, and finally impregnated and carbonized for densification at an impregnation pressure of 0.5-50 MPa and a carbonization temperature of 600-1000℃; the deposition raw material is one of natural gas, propylene, and propane.

4. The method according to claim 1, characterized in that, In step c(1), the fluorine-containing gas is sulfur hexafluoride or carbon tetrafluoride, the plasma processing power is 100-1000W, and the processing time is 1-30min.

5. The method according to claim 1, characterized in that, In step c(2), the rare earth silicate is selected from at least one of lutetium yttrium silicate and erbium yttrium silicate, and its particle size is 10-200 nm.

6. The method according to claim 1, characterized in that, In step c(2), the zeolite imidazole ester skeleton material is ZIF-8, and its particle size is 50-500nm.

7. The method according to claim 1, characterized in that, The dispersion preparation process is as follows: rare earth silicate nanoparticles and zeolite imidazole ester framework material are mixed in proportion, dispersed in anhydrous ethanol, and 5% of the total mass of dispersant polyvinylpyrrolidone is added. The mixture is then placed in an ultrasonic cell disruptor and ultrasonically treated for 30 minutes to form a milky white dispersion. The mass ratio of the rare earth silicate nanoparticles to the zeolite imidazole ester framework material is 1-10:10-1.

8. The method according to claim 1, characterized in that, In step c(3), the amino-functionalized ionic liquid is 1-aminopropyl-3-methylimidazolium tetrafluoroborate. The grafting process is as follows: first, prepare an ethanol solution of 1-aminopropyl-3-methylimidazolium tetrafluoroborate with a concentration of 5-10wt%, then immerse the inner mold in the solution, then transfer the immersion system to the reaction vessel, and under nitrogen protection, heat it to 80-90℃ and stir it magnetically for 4-6 hours. Then, take out the inner mold, rinse it repeatedly with anhydrous ethanol 3 times, and finally dry it to complete the grafting process.

9. The method according to claim 1, characterized in that, The resin used in step d is one of epoxy resin, phenolic resin, or furfuryl ketone resin.

10. The carbon-carbon composite helical blade rod prepared by the method according to any one of claims 1-9, characterized in that, The interfacial shear strength between the internal needle-punched structure and the external winding structure of the helical blade rod is not less than 25 MPa, and the coefficient of variation of the density uniformity of the helical blade rod in the length direction is not greater than 5%.

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