A rapidly densified high strength and toughness carbon-based composite material and a method for preparing the same

Abstract

The application belongs to the technical field of carbon-based thermal protection composite materials, and discloses a kind of quick densification high tenacity carbon-based composite material and its preparation method, its preparation steps include: 1) after mixing uniformly benzoxazine resin, solvent and ceramic precursor, heating, first impregnation liquid is prepared;2) first impregnation liquid is brushed on carbon fiber cloth, and naturally air-dried, to obtain pretreated carbon fiber cloth;3) after mixing uniformly benzoxazine resin, solvent, ceramic precursor and ceramic particles, second impregnation liquid is prepared;4) second impregnation liquid is brushed on pretreated carbon fiber cloth, and dried, to obtain prepreg;5) after laminating and laying up prepreg, mould pressing is formed, to obtain blank;6) blank is heated and pyrolyzed under inert atmosphere, to obtain carbon-based composite material.The carbon-based composite material of the application can be formed and simultaneously quickly densified in only one cycle, almost realizes full densification, porosity is less than 1.5vol%, and has excellent mechanical properties and thermal protection performance.

Description

Technical Field

[0001] This invention belongs to the field of carbon-based thermal protection composite materials technology, specifically relating to a rapidly densified high-strength and high-toughness carbon-based composite material and its preparation method. Background Technology

[0002] Carbon-based composites, with their high mechanical properties and lightweight characteristics under extreme service environments, are widely used in aerospace and defense equipment. However, existing manufacturing methods have significant drawbacks, primarily high cost and low efficiency. The manufacture of carbon-based composites typically begins with carbon fiber cloth. After pretreatment, the carbon fiber cloth is injected with precursor resin to obtain a preform. Subsequently, pyrolysis is required to form the matrix. The voids generated in the matrix after pyrolysis must be filled using methods such as chemical vapor infiltration (CVI), chemical vapor deposition (CVD), or polymer impregnation and pyrolysis (PIP) to achieve densification. However, these infiltration methods not only require specialized equipment but also consume considerable processing time. Furthermore, traditional manufacturing processes require at least five cycles of impregnation-pyrolysis to achieve the required matrix porosity. Multiple impregnation-pyrolysis cycles further increase manufacturing costs and extend processing times, limiting the application of carbon-based composites in many scenarios due to their high price.

[0003] Meanwhile, existing processes often require multiple rounds of repeated pyrolysis of carbon fiber cloth. During this process, carbon fibers are prone to oxidation and pyrolysis damage, making it difficult to fully realize their reinforcing effect and ultimately resulting in lower mechanical strength, failing to achieve the high strength and toughness performance target. Furthermore, existing carbon-based composite material manufacturing technologies also face challenges in product quality control. For example, in the carbon source introduction stage, whether using gas-phase or liquid-phase methods, it is difficult to achieve uniform filling of the gaps between carbon fibers, easily forming pores in the matrix. Even with multiple post-processing optimizations, these defects are difficult to completely eliminate. Moreover, during high-temperature processing, the material is prone to uneven shrinkage, directly leading to difficulties in accurately controlling the product density, further affecting the performance stability and application reliability of carbon-based composite materials.

[0004] Therefore, developing a rapid densification method for high-strength and high-toughness carbon-based composite materials and its preparation method is of great significance. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a rapid densification high-strength and tough carbon-based composite material and its preparation method, which addresses the shortcomings of the existing technology. The carbon-based composite material can be formed and rapidly densified in only one cycle, achieving almost full densification (porosity <1.5 vol%), and has excellent mechanical and thermal protection properties, meeting the comprehensive requirements of thermal protection products for high-performance and low-cost high-temperature resistant thermal structural materials.

[0006] To address the technical problem proposed in this invention, this invention provides a method for rapidly densifying high-strength and high-toughness carbon-based composite materials, comprising the following steps:

[0007] 1) After uniformly mixing benzoxazine resin, solvent and ceramic precursor, heat to obtain the first impregnation solution;

[0008] 2) Apply the first impregnation solution to the carbon fiber cloth and let it air dry to obtain the pretreated carbon fiber cloth.

[0009] 3) After uniformly mixing benzoxazine resin, solvent, ceramic precursor and ceramic particles, a second impregnation solution is prepared;

[0010] 4) Apply the second impregnation solution to the pretreated carbon fiber cloth by brushing, and dry to obtain the prepreg;

[0011] 5) After the prepreg is laid in layers, it is molded to obtain a blank;

[0012] 6) The blank is heated and decomposed under an inert atmosphere to obtain a carbon-based composite material.

[0013] In the above scheme, the benzoxazine resin has a carbon residue rate of >65% at 800℃.

[0014] In the above scheme, the solvent is one of ethyl acetate and toluene.

[0015] In the above scheme, the ceramic precursor is one of liquid polyborosilazane or liquid polysilazane.

[0016] Furthermore, the viscosity (25°C) of the liquid polyborosilicate is ≤20 mPa·s.

[0017] Furthermore, the viscosity (25°C) of the liquid polysilazane is ≤100 mPa·s.

[0018] In the above scheme, the ceramic particles include oxide ceramics and non-oxide ceramics.

[0019] Furthermore, the ceramic particles comprise 75-85% oxide ceramics by mass and 15-25% non-oxide ceramics by mass.

[0020] Furthermore, the oxide ceramic is one of ZrO2, MgO, or Al2O3.

[0021] Furthermore, the oxide ceramic has a particle size of 200~400nm and a purity of ≥99.9%.

[0022] Furthermore, the non-oxide ceramic has a particle size of 1~3μm and a purity of ≥99%.

[0023] Furthermore, the non-oxide ceramics include silicide ceramics and boride ceramics.

[0024] Furthermore, the silicide ceramic includes one or more of ZrSi2 and MoSi2.

[0025] Furthermore, the boride ceramic includes one or more of TiB2, ZrB2, and HfB2.

[0026] Furthermore, the mass ratio of the silicide ceramic to the boride ceramic is (5~9):1.

[0027] In the above scheme, the carbon fiber cloth is a plain weave carbon fiber cloth.

[0028] In the above scheme, the thickness of the carbon fiber cloth is 0.3~0.35mm.

[0029] In the above scheme, the carbon fiber cloth is one of 1K, 3K, or 6K, with a basis weight of 90~320g / m². 2 .

[0030] In the above scheme, in step 1), the mass ratio of the benzoxazine resin, solvent and ceramic precursor is 1:(1~1.2):(0.1~0.15).

[0031] In the above scheme, in step 1), the heating temperature is 60~110℃ and the heating time is 1~3h.

[0032] In the above scheme, the viscosity (25°C) of the first impregnation solution is 50~200 mPa·s.

[0033] In the above scheme, in step 2), the mass ratio of the first impregnation solution to the carbon fiber cloth is (1.6~1.85):1.

[0034] In the above scheme, the thickness of the pretreated carbon fiber cloth is 0.35~0.45mm.

[0035] In the above scheme, in step 3), the mass ratio of the benzoxazine resin, solvent, ceramic precursor and ceramic particles is 1:(1~1.2):(0.1~0.15):(0.05~0.2).

[0036] In the above scheme, the viscosity (25°C) of the second impregnation solution is 200~500 mPa·s.

[0037] In the above scheme, in step 4), the mass ratio of the second impregnation solution to the pretreated carbon fiber cloth is (2.15~2.55):1.

[0038] In the above scheme, the thickness of the prepreg is 0.5~0.6mm.

[0039] In the above scheme, in step 4), the drying temperature is 50~70℃ and the drying time is 2~4h.

[0040] In the above scheme, the compression molding adopts a stepped heating process, which includes six sequentially increasing constant temperature stages. The temperatures of the first to sixth stages are 85~95℃, 105~115℃, 125~135℃, 145~155℃, 175~185℃, and 205~215℃, respectively, and the duration of each stage is 1~1.5h independently.

[0041] Furthermore, the compression molding process maintains a pressure of 10-15 MPa in the second to sixth stages.

[0042] In the above scheme, the inert atmosphere is either nitrogen or argon.

[0043] Furthermore, the flow rate of the inert atmosphere is 100~200 mL / min.

[0044] In the above scheme, the pyrolysis temperature is 800~1000℃ and the holding time is 1~2h.

[0045] Furthermore, the heating rate for the thermal pyrolysis is 2~5℃ / min.

[0046] The present invention also provides a rapidly densified high-strength and high-toughness carbon-based composite material, which is prepared by the above method.

[0047] In the above scheme, the porosity of the carbon-based composite material is <1.5 vol%, the tensile strength is ≥450 MPa, the compressive strength is ≥110 MPa, and the flexural strength is ≥310 MPa.

[0048] In the above scheme, the carbon-based composite material maintains excellent mechanical strength in a high-temperature aerobic environment. After being subjected to a high temperature of ≥1200℃, the tensile strength is ≥240MPa, the compressive strength is ≥90MPa, and the flexural strength is ≥140MPa. It also exhibits excellent ablation resistance in a high-enthalpy ablation environment, with a heat flux density of 4186.8±418.68kW / m³. 2 After oxyacetylene flame ablation, the mass ablation rate is ≤0.0153g / s, and the linear ablation rate is ≤0.0187mm / s.

[0049] The main technical concept of this invention is as follows:

[0050] In traditional impregnation molding processes for carbon-based composite materials, the common method is to directly immerse the carbon fiber cloth in the impregnation solution to achieve matrix coating, followed by natural drying before high-temperature pyrolysis. This process is detrimental to the protection of the fiber cloth. This process suffers from three major technical shortcomings: First, the fiber cloth is susceptible to morphological distortion due to hydraulic and tensile forces during immersion, and the uniformity of the impregnation amount is difficult to control, easily leading to localized over-impregnation, under-impregnation, or resin enrichment. Second, rapid bonding between resin and fiber increases fiber bundle rigidity and reduces flexibility, making it difficult to meet the subsequent processing and molding requirements of complex-shaped components. Third, uneven resin distribution creates under-impregnation areas, leaving the carbon fibers in these areas without effective coating protection during high-temperature pyrolysis, making them prone to oxidation and structural damage, further deteriorating material properties. Furthermore, bottlenecks such as low residual carbon content in the matrix, numerous pyrolysis cycles, and long densification cycles hinder rapid densification, severely limiting large-scale applications. This invention breaks through these limitations through synergistic regulation of the "formulation-process":

[0051] First, the matrix raw materials of the carbon-based composite material of this invention include benzoxazine resin, solvent, ceramic precursor, and ceramic particles. The synergistic effect of these components endows the product with excellent performance. During curing, the benzoxazine resin undergoes only ring-opening polymerization and cross-linking reactions, without the generation of small-molecule byproducts, thus reducing porosity. Its aromatic groups readily transform into a stable carbon skeleton at high temperatures, resulting in extremely high residual carbon content, laying the foundation for the material's high-temperature resistance and ablation resistance. The small-molecule volatiles released during the pyrolysis stage can synergistically interact with the ceramic particles. After high-temperature pyrolysis, the ceramic precursor exhibits a dense, blocky structure with good process compatibility. The solid-phase products generated by the reaction with oxide ceramic particles can fill carbon layer defects, accelerating densification and shortening the process cycle. The ceramic particles are functionally differentiated according to their type: oxide ceramics, as the main phase, generate dense products through solid-phase reactions to fill pores, leading to material densification; non-oxide ceramics, as the reinforcing phase, can undergo solid-phase reactions with small-molecule gases generated during the pyrolysis of benzoxazine resin. The resulting reaction products are integrated into the carbon matrix structure through diffusion, in-situ growth, and other pathways. Ultimately, the benzoxazine resin, ceramic precursor, and ceramic particles undergo a single pyrolysis process to form a stable carbon-inorganic phase composite structure. This composite structure not only helps reduce the material's porosity but also optimizes load transfer efficiency through interfacial strengthening, avoiding interfacial delamination during stress. Simultaneously, the inorganic phase inhibits crack initiation and propagation, fully leveraging the reinforcing properties of carbon fibers, ultimately effectively enhancing the material's strength and toughness. Products prepared from these raw materials achieve low porosity with only a single pyrolysis step, while also possessing excellent mechanical load-bearing capacity and high-temperature thermal protection properties, meeting the comprehensive requirements of thermal protection products for high-performance and low-cost high-temperature resistant thermal structural materials.

[0052] Secondly, this invention innovatively designs a two-stage coating molding process. The first coating uses a pure resin-based system without ceramic particles, composed of benzoxazine resin, solvent, and ceramic precursor. Its excellent wetting and penetration characteristics allow for thorough impregnation of the carbon fiber cloth, eliminating the cumbersome pre-pyrolysis treatment required in traditional processes. On one hand, this pure resin system can uniformly form a dense protective film on the carbon fiber surface, effectively reducing the risk of damage to the carbon fiber during subsequent processing. On the other hand, by controlling the viscosity and interfacial interactions of the resin system, the inherent excellent flexibility of the carbon fiber can be preserved to the greatest extent, achieving comprehensive protection of the reinforcement. After the first coating, the internal pores and inter-fiber gaps of the carbon fiber cloth are fully filled, and the thickness is precisely controlled from the original 0.3~0.35mm to the 0.35~0.45mm range, laying the foundation for the smooth implementation of the subsequent second coating process and achieving rapid densification.

[0053] The second coating enhances the functionality of the first process. The second impregnation solution introduces ceramic particles as a reinforcing phase, building upon the first. In composite material systems, ceramic particles are the core reinforcing component: on one hand, their excellent mechanical properties synergize with the matrix, significantly improving the material's strength and toughness; on the other hand, the bonding and anchoring of the resin matrix and the gradient filling of the particles themselves constitute a dual mechanism promoting densification. Specifically, the resin matrix ensures uniform dispersion of ceramic particles and forms a stable bonding interface, while the ceramic particles precisely embed themselves into the micropores remaining in the cured layer of the first impregnation solution. The combination of these two aspects significantly accelerates the densification rate of the composite material. This second coating scheme ultimately produces a product with a complete microstructure and tight interfacial bonding, with the prepreg thickness controlled to 0.5~0.6mm after the second coating. The purpose of these two adjustments to the carbon fiber cloth thickness is to achieve precise matching of the carbon fiber volume fraction through step-by-step control, avoiding insufficient impregnation filling and interfacial bonding defects due to excessive fiber content, and also preventing weakening of the reinforcing effect due to excessively low fiber content, thereby affecting the material's mechanical strength and ablation resistance.

[0054] In subsequent processes, the prepreg is cut according to the component requirements, laminated and molded into blanks, and then subjected to high-temperature pyrolysis. Pyrolysis is the core step in achieving rapid densification of carbon-based composite materials, while ceramic particles can synergistically enhance this process through a dual reaction pathway: oxide ceramics act as a densifying agent, and the solid products generated by the reaction with the ceramic precursor can precisely fill carbon layer defects, significantly accelerating densification and shortening the process cycle. Non-oxide ceramics act as a reinforcing agent, with a clear logic for strengthening and toughening: they can undergo a solid-phase reaction with the small molecule gas generated by the pyrolysis of benzoxazine resin, and the products are integrated into the carbon matrix through diffusion, in-situ growth, and other methods. Finally, benzoxazine resin, ceramic precursor, and ceramic particles form a stable "carbon-inorganic phase" composite structure after one pyrolysis. This structure not only reduces porosity but also optimizes load transfer efficiency through interface strengthening, preventing interface delamination under stress. At the same time, the inorganic phase can hinder crack propagation, fully releasing the carbon fiber reinforcement effect, thereby significantly improving the strength and toughness of the material. The two form a "densification-strengthening" synergistic mechanism to jointly ensure the overall performance of the product.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] The carbon-based composite material of this invention can be molded and rapidly densified in just one cycle, with a single-cycle pyrolysis porosity of <1.5 vol%, a tight matrix and reinforcement arrangement, and a defect size of <100 μm. Its preparation process is simple and can significantly shorten the production time. The resulting product has excellent mechanical properties, thermal protection properties, and ablation properties, which can meet the comprehensive requirements of future advanced aircraft for high-performance and low-cost high-temperature thermal structural materials. Attached Figure Description

[0057] Figure 1 This is a photograph of the carbon-based composite material sample prepared in Example 1.

[0058] Figure 2 The image shows the microstructure of the carbon-based composite material sample prepared in Example 1.

[0059] Figure 3 The image shows the XRD pattern of the carbon-based composite material sample prepared in Example 1.

[0060] Figure 4 This is a photograph of the carbon-based composite material sample prepared in Example 1 after the oxyacetylene test. Detailed Implementation

[0061] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0062] Example 1

[0063] The benzoxazine resin used in this embodiment is CG450 produced by Chengdu Keyi Polymer Technology Co., Ltd., with a residual carbon rate of 77% at 800℃; the liquid polyborosilicate is ZQ-B10 produced by Zibo Linzi Qiquan Industry and Trade Co., Ltd., with a viscosity (25℃) of 18 mPa·s and a ceramicization yield of ≥60% under an argon atmosphere at 1200℃; the ZrO2 particles have a particle size of 200 nm and a purity of ≥99.9%; the ZrSi2 particles have a particle size of 3 μm and a purity of ≥99.5%; the TiB2 particles have a particle size of 1 μm and a purity of ≥99%; the carbon fiber cloth is plain weave carbon fiber cloth, model T300, specification 3K, with a basis weight of 200 g / m². 2 Thickness 0.30mm.

[0064] This embodiment prepares a rapidly densified high-strength and tough carbon-based composite material, specifically including the following steps:

[0065] (1) Benzoxazine resin, ethyl acetate and liquid polyborosilicate are mixed in a mass ratio of 1:1:0.1 and the mixture is fully dissolved by mechanical stirring to obtain a mixture. The mixture is placed in an oven at 60°C for 2 hours to obtain a first impregnation solution with a viscosity of 126 mPa·s.

[0066] (2) The first impregnation solution is applied to the carbon fiber cloth. The mass ratio of the first impregnation solution to the carbon fiber cloth is 1.6:1. After application, the cloth is naturally dried to obtain a pretreated carbon fiber cloth with a thickness of 0.38 mm.

[0067] (3) Mix benzoxazine resin, ethyl acetate and liquid polyborosilicate, and then dop ceramic particles (ZrO2 accounts for 80wt%, ZrSi2+TiB2 accounts for 20wt%, and the mass ratio of ZrSi2 and TiB2 is 7:1). The mass ratio of benzoxazine resin, ethyl acetate, liquid polyborosilicate and ceramic particles is 1:1:0.1:0.1. Stir mechanically until uniform, and prepare a second impregnation solution with a viscosity of 358 mPa·s.

[0068] (4) The second impregnation solution is brushed onto the pretreated carbon fiber cloth. The mass ratio of the second impregnation solution to the pretreated carbon fiber cloth is 2.2:1. The prepreg is treated in an oven at 50°C for 4 hours to obtain a prepreg with a thickness of 0.58 mm.

[0069] (5) Cut the prepreg into regular sizes, stack them in the mold, and then place them in a flat vulcanizing machine for molding. First, heat the material to 90°C and keep it at that temperature for 1 hour. Then, heat the material to 110°C and adjust the pressure to 12MPa and keep it at that temperature for 1 hour. Then, maintain the pressure and continue to heat the material to 130°C and keep it at that temperature for 1 hour, 150°C and keep it at that temperature for 1 hour, 180°C and keep it at that temperature for 1 hour, and 210°C and keep it at that temperature for 1 hour to make a blank.

[0070] (6) The blank is placed in a tube furnace and heated to 800℃ for 2 hours under nitrogen atmosphere (nitrogen flow rate of 150 mL / min) at a heating rate of 4℃ / min to obtain carbon-based composite material product.

[0071] Figure 1 The image shows the actual carbon-based composite material sample prepared in this embodiment. It can be seen that the sample has a complete, uniform and dense appearance.

[0072] Figure 2 The image shows the microstructure of the carbon-based composite material sample prepared in this embodiment. It can be observed that the matrix and reinforcement of the product sample are tightly bonded and almost no obvious defects are visible, indicating that it can be rapidly densified after one pyrolysis. The maximum defect size after pyrolysis is roughly estimated to be <100μm.

[0073] Figure 3 The image shows the XRD pattern of the carbon-based composite material sample prepared in this embodiment. The figure shows that after pyrolysis, the reaction produces ZrO2, SiO2, ZrSiO4, TiO2, B2O3, and C, which proves that ZrSi2 and TiB2 react with the small gas molecules released by the pyrolysis of benzoxazine resin to generate these solid-phase reaction products. The broad peaks (a) and (b) observed at 2θ angles of approximately 23~24° and 42~44° are characteristic peaks of amorphous carbon, which improves the char yield.

[0074] Example 2

[0075] The benzoxazine resin used in this embodiment is CG450 produced by Chengdu Keyi Polymer Technology Co., Ltd., with a residual carbon rate of 77% at 800℃; the liquid polysilazane is ZQ-N50 produced by Zibo Linzi Qiquan Industry and Trade Co., Ltd., with a viscosity (25℃) of 95 mPa·s and a ceramicization yield of ≥70% under an argon atmosphere at 1000℃; the MgO particles have a particle size of 200 nm and a purity of ≥99.9%; the MoSi2 particles have a particle size of 2 μm and a purity of ≥99.9%; the ZrB2 particles have a particle size of 1 μm and a purity of ≥99.5%; the carbon fiber cloth is plain weave carbon fiber cloth, model T300, specification 3K, with a basis weight of 200 g / m². 2 Thickness 0.30mm.

[0076] This embodiment prepares a rapidly densified high-strength and tough carbon-based composite material, specifically including the following steps:

[0077] (1) Mix benzoxazine resin, toluene and liquid polysilazane at a mass ratio of 1:1.1:0.11, and after mechanical stirring to fully dissolve, prepare a mixture. Place the mixture in an oven at 110°C for 1 hour to obtain a first impregnation solution with a viscosity of 138 mPa·s.

[0078] (2) The first impregnation solution is applied to the carbon fiber cloth. The mass ratio of the first impregnation solution to the carbon fiber cloth is 1.7:1. After application, the cloth is naturally dried to obtain a pretreated carbon fiber cloth with a thickness of 0.36 mm.

[0079] (3) Mix benzoxazine resin, toluene and liquid polysilazane, and then dop ceramic particles (MgO accounts for 75wt%, MoSi2+ZrB2 accounts for 25wt%, and the mass ratio of MoSi2 and ZrB2 is 9:1). The mass ratio of benzoxazine resin, ethyl acetate, liquid polysilazane and ceramic particles is 1:1.1:0.11:0.11. Stir mechanically until uniform, and prepare a second impregnation solution with a viscosity of 315 mPa·s.

[0080] (4) The second impregnation solution is brushed onto the pretreated carbon fiber cloth. The mass ratio of the second impregnation solution to the pretreated carbon fiber cloth is 2.32:1. The prepreg is treated in an oven at 60°C for 3 hours to obtain a prepreg with a thickness of 0.55 mm.

[0081] (5) Cut the prepreg into regular sizes, stack them in the mold, and then place them in a flat vulcanizing machine for molding. First, heat the material to 95°C and keep it at that temperature for 1 hour. Then, heat the material to 115°C and adjust the pressure to 13MPa and keep it at that temperature for 1 hour. Then, maintain the pressure and continue to heat the material to 135°C and keep it at that temperature for 1 hour, 155°C and keep it at that temperature for 1 hour, 185°C and keep it at that temperature for 1 hour, and 215°C and keep it at that temperature for 1 hour to make a blank.

[0082] (6) The blank is placed in a tube furnace and heated to 900℃ for 1.5h under nitrogen atmosphere (nitrogen flow rate of 160mL / min) at a heating rate of 3℃ / min to obtain carbon-based composite material product.

[0083] Example 3

[0084] The benzoxazine resin used in this embodiment is CG450 produced by Chengdu Keyi Polymer Technology Co., Ltd., with a residual carbon rate of 77% at 800℃; the liquid polysilazane is ZQ-N50 produced by Zibo Linzi Qiquan Industry and Trade Co., Ltd., with a viscosity (25℃) of 95 mPa·s and a ceramicization yield of ≥70% under an argon atmosphere at 1000℃; the MgO particles have a particle size of 200 nm and a purity of ≥99.9%; the ZrSi2 particles have a particle size of 3 μm and a purity of ≥99.5%; the HfB2 particles have a particle size of 1 μm and a purity of ≥99%; the carbon fiber cloth is plain weave carbon fiber cloth, model T300, specification 3K, with a basis weight of 200 g / m². 2 Thickness 0.30mm.

[0085] This embodiment prepares a rapidly densified high-strength and tough carbon-based composite material, specifically including the following steps:

[0086] (1) Benzoxazine resin, ethyl acetate and liquid polysilazane are mixed in a mass ratio of 1:1.2:0.12 and the mixture is fully dissolved by mechanical stirring to obtain a mixture. The mixture is placed in an oven at 60°C for 1 hour to obtain a first impregnation solution with a viscosity of 118 mPa·s.

[0087] (2) The first impregnation solution is applied to the carbon fiber cloth. The mass ratio of the first impregnation solution to the carbon fiber cloth is 1.8:1. After application, the cloth is naturally dried to obtain a pretreated carbon fiber cloth with a thickness of 0.41 mm.

[0088] (3) Mix benzoxazine resin, ethyl acetate and liquid polysilazane, and then dop ceramic particles (MgO accounts for 85wt%, ZrSi2+HfB2 accounts for 15wt%, and the mass ratio of ZrSi2 and HfB2 is 6:1). The mass ratio of benzoxazine resin, ethyl acetate, liquid polysilazane and ceramic particles is 1:1.2:0.12:0.12. Stir mechanically to prepare a second impregnation solution with a viscosity of 332 mPa·s.

[0089] (4) The second impregnation solution is brushed onto the pretreated carbon fiber cloth. The mass ratio of the second impregnation solution to the pretreated carbon fiber cloth is 2.44:1. The prepreg is treated in an oven at 70°C for 2 hours to obtain a prepreg with a thickness of 0.59 mm.

[0090] (5) Cut the prepreg into regular sizes, stack them in the mold, and then place them in a flat vulcanizing machine for molding. First, heat the material to 85°C and hold for 1.5 hours. Then, heat the material to 105°C and adjust the pressure to 11MPa and hold for 1.5 hours. Then, maintain the pressure and continue to heat the material to 125°C and hold for 1.5 hours, 145°C and 175°C and 205°C and hold for 1.5 hours to make a blank.

[0091] (6) The blank is placed in a tube furnace and heated to 1000℃ for 1h under nitrogen atmosphere (nitrogen flow rate of 180mL / min) at a heating rate of 2℃ / min to obtain carbon-based composite material product.

[0092] Comparative Example 1

[0093] The only difference between Comparative Example 1 and Example 1 is that a single coating-drying-pyrolysis process is adopted, i.e. steps 1) and 2) are not performed, and the second impregnation solution is directly coated onto the fiber cloth.

[0094] Comparative Example 2

[0095] The only difference between Comparative Example 2 and Example 1 is that the same dipping solution was used for both coatings, i.e., the first dipping solution was used in both steps 2) and 4).

[0096] Comparative Example 3

[0097] The only difference between Comparative Example 3 and Example 1 is that neither the first impregnation solution nor the second impregnation solution contains a ceramic precursor.

[0098] Comparative Example 4

[0099] The only difference between Comparative Example 4 and Example 1 is that the ceramic particles are ZrO2.

[0100] Performance testing

[0101] Performance tests were conducted on the samples prepared in each embodiment and comparative example. Specifically: the porosity of the pyrolysis finished sample was tested according to GB / T 2997-2015; the mechanical properties of the pre-pyrolysis blank sample, the pyrolysis finished sample, and the finished sample after 1200℃ aerobic heat test for 10 min were tested using a microcomputer-controlled electronic universal testing machine according to GB / T 1447-2005, GB / T 1448-2005, and GB / T1449-2005; and the pyrolysis finished product was processed into Φ30×10mm ablation samples according to GJB323B-2018 standard, and the samples were ablated using an oxyacetylene flame in an air atmosphere.

[0102] Table 1

[0103]

[0104] Table 2

[0105]

[0106] As can be seen from Tables 1 and 2, the carbon-based composite material prepared in this embodiment possesses excellent room-temperature and high-temperature mechanical properties, and exhibits high strength retention after high-temperature heat treatment; the heat flux density is 4168.8 kW / m³. 2 After being ablated by an oxyacetylene flame for 30-150 seconds, the carbon-based composite material sample still maintained its structural integrity, indicating that it has good ablation resistance.

[0107] Comparative Example 1, due to its single-coating process and lack of sufficient impregnation of the carbon fiber cloth with the first impregnation solution, suffered mechanical damage to the fiber surface or interfacial bonding defects, resulting in significantly inferior performance compared to all other examples. Comparative Example 2, although employing a two-coating strategy, used a first impregnation solution without ceramic particles in both coats, lacking the synergistic effect of ceramic particle filling reinforcement and solid-phase reaction. This resulted in a significant increase in matrix porosity and a loose carbon layer structure, thus significantly inferior performance compared to all other examples. Comparative Example 3, lacking the addition of a ceramic precursor, lost its synergistic densification effect with ceramic particles, leading to insufficient solid-phase reaction products during pyrolysis and increased matrix porosity, resulting in significantly lower overall material performance compared to all other examples. Comparative Example 4, lacking the introduction of non-oxide ceramic particles, could neither effectively capture the small molecule gases released during the pyrolysis stage of the benzoxazine resin nor form a sufficient and stable "carbon-inorganic phase" composite structure, resulting in suboptimal densification and toughening effects, and significantly inferior overall performance compared to all other examples.

[0108] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for producing a rapidly densified high strength and toughness carbon-based composite material, characterized by, The method comprises the following steps: 1) uniformly mixing a benzoxazine resin, a solvent and a ceramic precursor, and heating to obtain a first impregnating solution; 2) brushing the first impregnating solution on a carbon fiber cloth, and naturally drying to obtain a pretreated carbon fiber cloth; 3) uniformly mixing the benzoxazine resin, the solvent, the ceramic precursor and ceramic particles to obtain a second impregnating solution; 4) brushing the second impregnating solution on the pretreated carbon fiber cloth, and drying to obtain a prepreg; 5) laminating and molding the prepreg to obtain a blank; 6) heating and pyrolyzing the blank in an inert atmosphere to obtain a carbon-based composite material. The ceramic precursor is one of liquid polysilazane and liquid polyborosilazane. The ceramic particles comprise 75-85% of oxide ceramic and 15-25% of non-oxide ceramic by mass; the oxide ceramic is one of ZrO2, MgO and Al2O3; the non-oxide ceramic is composed of silicide ceramic and boride ceramic at a mass ratio of (5-9):1; the silicide ceramic comprises one or more of ZrSi2 and MoSi2; the boride ceramic comprises one or more of TiB2, ZrB2 and HfB2.

2. The method of producing a rapid densification high strength and toughness carbon-based composite material according to claim 1, characterized by, The solvent is one of ethyl acetate and toluene; the thickness of the carbon fiber cloth is 0.3-0.35 mm.

3. The method of producing a rapid densified high strength and toughness carbon-based composite material according to claim 1, wherein The 800℃ carbon residue rate of the benzoxazine resin is >65%; the viscosity of the liquid polysilazane is ≤20mPa·s; the viscosity of the liquid polysilazane is ≤100mPa·s; the particle size of the oxide ceramic is 200-400nm, and the purity is ≥99.9%; the particle size of the non-oxide ceramic is 1-3μm, and the purity is ≥99%; the carbon fiber cloth is one of 1K, 3K, 6K, and the grammage is 90-320g / m 2 .

4. The method of producing a rapid densified high strength and toughness carbon-based composite material according to claim 1, wherein In step 1), the mass ratio of the benzoxazine resin, the solvent and the ceramic precursor is 1:(1-1.2):(0.1-0.15); the viscosity of the first impregnating solution is 50-200 mPa·s; the mass ratio of the first impregnating solution and the carbon fiber cloth is (1.6-1.85):1; the thickness of the pretreated carbon fiber cloth is 0.35-0.45 mm.

5. The method of producing a rapid densified high strength and toughness carbon-based composite material according to claim 1, wherein In step 3), the mass ratio of the benzoxazine resin, the solvent, the ceramic precursor and the ceramic particles is 1:(1-1.2):(0.1-0.15):(0.05-0.2); the viscosity of the second impregnating solution is 200-500 mPa·s; the mass ratio of the second impregnating solution and the pretreated carbon fiber cloth is (2.15-2.55):1; the thickness of the prepreg is 0.5-0.6 mm.

6. The method of producing a rapid densified high strength and toughness carbon-based composite material according to claim 1, wherein The molding comprises six constant-temperature stages in sequence, the temperatures of the first to sixth stages are 85-95℃, 105-115℃, 125-135℃, 145-155℃, 175-185℃ and 205-215℃ in sequence, and the duration of each stage is independently 1-1.5 h; the molding is kept at a pressure of 10-15 MPa in the second to sixth stages.

7. The method of producing a rapid densified high strength and toughness carbon-based composite material according to claim 1, wherein The pyrolysis temperature is 800-1000℃, the holding time is 1-2 h, the heating rate of the pyrolysis is 2-5℃ / min, the heating temperature in step 1) is 60-110℃, and the heating time is 1-3 h; the drying temperature in step 4) is 50-70℃, and the drying time is 2-4 h.

8. A rapidly densified high strength and toughness carbon-based composite material prepared by the method of any one of claims 1 to 7, characterized in that, The carbon-based composite material has a porosity of <1.5 vol%, a tensile strength of ≥450 MPa, a compressive strength of ≥110 MPa and a bending strength of ≥310 MPa.

9. The rapid densified high strength to toughness carbon matrix composite of claim 8, wherein, The carbon-based composite material has a tensile strength of greater than or equal to 240 MPa, a compressive strength of greater than or equal to 90 MPa, and a bending strength of greater than or equal to 140 MPa after high-temperature treatment at greater than or equal to 1200 DEG C; and a heat flow density of 4186.8+ / - 418.68 kW / m 2 After ablation by an oxyacetylene flame, the mass ablation rate is less than or equal to 0.0153 g / s, and the linear ablation rate is less than or equal to 0.0187 mm / s.

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