Preparation method of high-density carbon-carbon composite material

Abstract

The invention relates to a preparation method of a high-density carbon-carbon composite material, and relates to the technical field of carbon-carbon composites.The preparation method comprises the following steps that materials are mixed, specifically, a binding material and auxiliary materials are mixed, and slurry is obtained; dipping a carbon fiber material in the slurry, and taking out the carbon fiber material to obtain a carbon fiber prepreg; performing: laminating and pre-pressing the carbon fiber prepreg to obtain a pre-pressed carbon fiber material; final forming: performing hot press forming on the pre-pressed carbon fiber material to obtain a carbon fiber semi-finished product; dipping: preparing a cementing material into an impregnant, carrying out pressurized dipping on the carbon fiber semi-finished product in the impregnant, maintaining the pressure after dipping, and carrying out heating curing to obtain a dipped semi-finished product; carbonization: carrying out carbonization treatment on the impregnated semi-finished product in an inert gas atmosphere to obtain a carbonized material; graphitization: carrying out graphitization treatment on the carbonized material in an inert gas atmosphere to obtain the high-density carbon-carbon composite material. The effect of improving the density of the carbon-carbon composite material is achieved, and the material has high strength and high heat conductivity.

Description

Technical Field

[0001] This application relates to the technical field of carbon-carbon composite materials, and particularly to a preparation method of high-density carbon-carbon composite materials. Background Art

[0002] With the rapid development of modern industry, the requirements for material properties in fields such as aerospace, automotive manufacturing, and high-end equipment have become increasingly stringent. Among many materials, carbon-carbon composite materials have become one of the ideal candidate materials for key components in these fields due to their excellent high-temperature stability, outstanding mechanical properties, and good chemical inertness. However, traditional carbon-carbon composite materials have certain limitations in terms of density, making it difficult to meet some application scenarios with extremely high requirements for material density and structural compactness, which has to a certain extent restricted their wider application and the full play of their performance.

[0003] Currently, in the preparation process of carbon-carbon composite materials, there are generally technical problems such as high porosity and difficulty in density improvement. Existing preparation processes often cannot fully fill the pores of the carbon fiber preform with the impregnating agent, resulting in more voids inside the material, which in turn affects the density and overall performance of the material, so improvement is needed. Summary of the Invention

[0004] In order to improve the density of carbon-carbon composite materials, this application provides a preparation method of high-density carbon-carbon composite materials.

[0005] The preparation method of high-density carbon-carbon composite materials provided by this application adopts the following technical scheme:

[0006] A preparation method of high-density carbon-carbon composite materials includes the following steps:

[0007] (1) Mixing: Mix the gelling material and auxiliary materials to obtain a slurry; immerse the carbon fiber material in the slurry, and then take it out to obtain a carbon fiber prepreg;

[0008] (2) Pre-forming: Stack and pre-press the carbon fiber prepreg to obtain a pre-pressed carbon fiber material;

[0009] (3) Final forming: Thermoform the pre-pressed carbon fiber material to obtain a carbon fiber semi-finished product;

[0010] (4) Impregnation: Prepare the gelling material into an impregnating agent, pressurize and impregnate the carbon fiber semi-finished product in the impregnating agent, keep the pressure after impregnation is completed, and raise the temperature for curing to obtain an impregnated semi-finished product;

[0011] (5) Carbonization: Carbonize the impregnated semi-finished product in an inert gas atmosphere to obtain a carbonized material;

[0012] (6) Graphitization: The carbonized material is graphitized under an inert gas atmosphere to obtain a high-density carbon-carbon composite material.

[0013] A gelling material with a certain residual carbon rate is mixed with auxiliary materials for filling to form a slurry. The carbon fiber material is impregnated therein, so that the gelling material and the auxiliary materials are uniformly attached to the carbon fiber, creating conditions for subsequent density increase. After the carbon fiber prepregs are laminated, they are pre-pressed at an appropriate temperature and pressure to make the laminated material tightly combined and regular in shape, which can initially improve the density of the material. The pre-pressed material is hot-pressed at high temperature and high pressure to obtain a carbon fiber semi-finished product. During this process, the material can be partially carbonized. An impregnating agent is prepared with the gelling material, and the semi-finished product is subjected to multiple impregnation treatments under a pressurized environment to allow the impregnating agent to fully penetrate the pores. Then, through heating and curing, the impregnating agent reacts at high temperature, further filling the pores and transforming into a carbonaceous component, increasing the density of the material. Carbonization is carried out in an inert gas atmosphere, and high temperature promotes the further densification and stabilization of the material structure. Graphitization treatment at high temperature makes the carbon structure in the material more regular and orderly. Through this series of material transformation and structure optimization processes, the density and performance of the material are effectively improved, thereby obtaining a high-density carbon-carbon composite material with good performance.

[0014] Preferably, the mass ratio of the carbon fiber material, the gelling material, and the auxiliary materials is (0.2 - 0.6):1:(0.05 - 0.3).

[0015] The material prepared according to the above mass ratio has good performance. The carbon fiber material can provide the strength and rigidity foundation of the composite material. The gelling material, as the matrix, can fully wrap and bond the carbon fiber material and the auxiliary materials, providing integrity and stability for the material and ensuring the integrity and reliability of the material structure under different working conditions. The auxiliary materials can change the thermal performance, oxidation resistance, etc. of the material, making it suitable for harsh environments such as high temperature and oxidation, and broadening the application range of the material. By precisely controlling the mass ratio of the three, a carbon-carbon composite material with high strength, high modulus, and good thermal conductivity can be prepared.

[0016] Preferably, the preparation raw materials of the auxiliary materials include nano-silicon powder, graphene, and silane coupling agent.

[0017] Nanosilica powder has high activity and small-size effect, and can be evenly dispersed in the composite material system, filling the microscopic voids between carbon fibers and cementitious materials, improving the density of the material, thereby enhancing the tensile strength and shear strength of the material. At the same time, the thermal conductivity of nanosilica powder itself helps to enhance the internal heat conduction path of the material and improve the overall thermal conductivity; Graphene has excellent two-dimensional sheet structure and high thermal conductivity, and can form an efficient heat conduction channel in the composite material, further improving the thermal conductivity of the material, enabling heat to be quickly and evenly distributed inside the material, avoiding local overheating, and the high strength and high modulus characteristics of graphene also help to enhance the overall mechanical properties of the material, and the large specific surface area and good flexibility also help to be evenly dispersed in the system, promoting the improvement of the material density; The silane coupling agent plays a bridging role. One end of it can chemically bond with the active groups on the surfaces of nanosilica powder and graphene, and the other end forms a good interfacial bond with the cementitious material, effectively improving the dispersion of nanosilica powder and graphene in the cementitious material, preventing the occurrence of agglomeration phenomenon, enabling nanosilica powder and graphene to be evenly dispersed, giving full play to their performance advantages, and then comprehensively improving the density, thermal conductivity, tensile strength and shear strength of the high-density carbon-carbon composite material, and optimizing the comprehensive performance of the material.

[0018] Preferably, the raw materials for preparing the cementitious material include bismaleimide, phenolic resin and benzoxazine-modified silsesquioxane.

[0019] Bismaleimide has a highly crosslinked structure and forms a tight and stable network after curing, filling the microscopic pores inside the material, reducing the voids inside the material, effectively improving the density, and at the same time enhancing the overall structural stability of the material and increasing the tensile strength and shear strength. Its regular molecular arrangement also helps with heat conduction; Phenolic resin has good fluidity and filling properties, can fully fill the gaps between various raw materials during mixing, further improve the density of the material, and can infiltrate other raw materials to improve dispersion. The chemical bonds formed during curing can also enhance the mechanical properties; The unique cage-like structure of benzoxazine-modified silsesquioxane can restrict the movement of molecular chains, enabling the material to maintain a tight structure during curing and use, improving the thermal stability and dimensional stability, being conducive to increasing the density, optimizing the crosslinked network, strengthening the internal chemical bonds, and synergistically enhancing the tensile strength and shear strength; The three act synergistically. The high density and high crosslinking enable the cementitious material to have a high char yield at high temperatures, forming a stable carbonaceous structure, which can comprehensively improve the density, thermal conductivity, tensile strength and shear strength of the high-density carbon-carbon composite material, meeting the stringent requirements for high performance of the material under complex working conditions.

[0020] Preferably, the mass ratio of bismaleimide, phenolic resin and benzoxazine-modified silsesquioxane is 1:0.75:(0.1 - 0.2).

[0021] The gelling material prepared according to the above mass ratio has good properties and can effectively improve the density, thermal conductivity, tensile strength and shear strength of the material.

[0022] Preferably, the raw materials for preparing the bismaleimide include maleic anhydride and 2,6-diaminopyridine.

[0023] The bismaleimide formed by the condensation reaction of maleic anhydride and 2,6-diaminopyridine contains rigid aromatic rings and imide groups in its molecular structure. These structural units can form a highly regular and tight crosslinked network during the curing process, effectively filling the microscopic voids inside the material and improving the density of the material; the highly crosslinked structure enhances the interaction between molecular chains and improves the ability to transmit loads, thus significantly increasing the tensile strength and shear strength of the material; at the same time, this regular molecular arrangement is beneficial to the transmission of phonons, reduces the thermal resistance, provides a good channel for the rapid conduction of heat, and further enhances the thermal conductivity of the material; bismaleimide has good compatibility and chemical reactivity with phenolic resin and benzoxazine modified silsesquioxane, and can further optimize the overall network structure of the gelling material, synergistically improving the performance of high-density carbon-carbon composites in terms of density, thermal conductivity, tensile strength and shear strength.

[0024] Preferably, the raw materials for preparing the benzoxazine modified silsesquioxane include octaphenylamino cage silsesquioxane, hydroquinone and formaldehyde.

[0025] Octaphenylamino cage silsesquioxane has a unique cage structure, which can play a role in physical support and space filling in the material system, effectively restricting the movement of molecular chains, thereby improving the density of the material, reducing internal voids, providing a more continuous path for heat conduction, and helping to improve the thermal conductivity; the phenylamino group has high reactivity and can undergo a condensation reaction with hydroquinone and formaldehyde to form a benzoxazine ring, further enhancing the interaction between molecules, optimizing the internal structure of the material, and increasing the tensile strength and shear strength; hydroquinone and formaldehyde not only participate in the construction of the benzoxazine ring in the reaction, but also the crosslinked structure formed during the reaction can enhance the integrity and stability of the material, further improving the density and mechanical properties; benzoxazine modified silsesquioxane has good synergistic effects with bismaleimide, phenolic resin and other gelling material components. The benzoxazine ring structure and the rigid structure of bismaleimide complement each other, jointly constructing a more compact, stable and efficient crosslinked network, thereby improving the density, thermal conductivity, tensile strength and shear strength of the material.

[0026] Preferably, the benzoxazine modified silsesquioxane is prepared by the following steps:

[0027] Hydroquinone and octaphenylaminocage silsesquioxane are mixed and dispersed in ethanol. After heating, formaldehyde is added. After the addition is complete, p-toluenesulfonic acid is added. The temperature is raised and stirred for reaction. After cooling, the product is washed with water, and the organic phase is obtained by liquid separation. The organic phase is concentrated by rotary evaporation. The concentrated organic phase is poured into hexane for precipitation. The precipitate is collected and dried to obtain benzoxazine-modified silsesquioxane.

[0028] The benzoxazine-modified silsesquioxane prepared according to the above mass ratio has good properties and can effectively improve the density, thermal conductivity, tensile strength and shear strength of the material.

[0029] Preferably, the impregnating agent includes a gelling material, butyl glycidyl ether and allyl cresol.

[0030] As an active diluent, butyl glycidyl ether has low viscosity, can improve the fluidity of the impregnating agent, make it easier to penetrate into the fine pores inside the material, and make the gelling material more evenly distributed, thus improving the density of the material; at the same time, the epoxy groups of butyl glycidyl ether can participate in the curing reaction and form a closer cross-linked structure with the gelling material, further enhancing the mechanical properties and stability of the material, optimizing the heat conduction path, and improving the thermal conductivity; allyl cresol can reduce the surface tension between the impregnating agent and the surface of carbon fiber, improve the wettability of the impregnating agent on the surface of carbon fiber, make the impregnation process more uniform and sufficient, reduce internal defects, improve the density, and allyl cresol can also react with other components during the curing process, enhance the intermolecular force, help to improve the tensile strength and shear strength of the material, improve the thermal stability of the material, and then synergistically improve the density, thermal conductivity, tensile strength and shear strength of the material.

[0031] Preferably, the mass ratio of the gelling material, butyl glycidyl ether and allyl cresol is 1:(0.1 - 0.3):0.1.

[0032] The impregnating agent prepared according to the above mass ratio has good wettability and can effectively improve the density, thermal conductivity, tensile strength and shear strength of the material.

[0033] In summary, the present application includes at least one of the following beneficial technical effects:

[0034] A gelling material with a certain residual carbon rate is mixed with auxiliary materials for filling to make a slurry. The carbon fiber material is impregnated therein, so that the gelling material and the auxiliary materials are uniformly attached to the carbon fiber, creating conditions for subsequent density increase. The carbon fiber prepregs are laminated and pre-pressed at an appropriate temperature and pressure to make the laminated materials closely combined and in regular shape, which can initially improve the compactness of the materials. The pre-pressed materials are hot-pressed under high temperature and high pressure to obtain semi-finished carbon fiber products. In this process, the materials can be partially carbonized. An impregnating agent is prepared with the gelling material, and the semi-finished products are subjected to multiple impregnation treatments under a pressurized environment, so that the impregnating agent fully penetrates into the pores. Then, through heating and curing, the impregnating agent reacts at high temperature, further fills the pores and is transformed into a carbonaceous component, increasing the material density. Carbonization is carried out in an inert gas atmosphere, and high temperature promotes the further densification and stabilization of the material structure. Graphitization treatment at high temperature makes the carbon structure in the material more regular and orderly. Through this series of material transformation and structure optimization processes, the density and performance of the materials are effectively improved, thus obtaining a high-density carbon-carbon composite material with good performance.

[0035] Bismaleimide has a highly cross-linked structure and forms a tight and stable network after curing, filling the microscopic pores inside the material, reducing the voids inside the material, effectively improving the density, and at the same time enhancing the overall structural stability of the material, increasing the tensile strength and shear strength. Its regular molecular arrangement also helps with heat conduction. Phenolic resin has good fluidity and filling properties, can fully fill the gaps between various raw materials during mixing, further improve the density of the material, and can infiltrate other raw materials to improve the dispersibility. The chemical bonds formed during curing can also enhance the mechanical properties. The unique cage-like structure of benzoxazine-modified silsesquioxane can restrict the movement of molecular chains, keep the material in a tight structure during curing and use, improve the thermal stability and dimensional stability, facilitate the improvement of density, optimize the cross-linking network, strengthen the internal chemical bonds, and synergistically increase the tensile strength and shear strength. The synergistic effect of the three makes the gelling material have a high residual carbon rate at high temperature due to high density and high cross-linking, forming a stable carbonaceous structure, which can comprehensively improve the density, thermal conductivity, tensile strength and shear strength of the high-density carbon-carbon composite material, meeting the stringent requirements for high performance of materials under complex working conditions.

[0036] As an active diluent, butyl glycidyl ether has a low viscosity, which can improve the fluidity of the impregnating agent, making it easier to penetrate into the fine pores inside the material, enabling the cementitious material to be more evenly distributed, thereby improving the density of the material. At the same time, the epoxy groups of butyl glycidyl ether can participate in the curing reaction, forming a tighter cross-linked structure with the cementitious material, further enhancing the mechanical properties and stability of the material, optimizing the heat conduction path, and improving the thermal conductivity. Allyl cresol can reduce the surface tension between the impregnating agent and the surface of the carbon fiber, improve the wettability of the impregnating agent on the surface of the carbon fiber, make the impregnation process more uniform and sufficient, reduce internal defects, improve the density, and allyl cresol can also react with other components during the curing process, enhancing the intermolecular force, contributing to improving the tensile strength and shear strength of the material, improving the thermal stability of the material, and thus synergistically improving the density, thermal conductivity, tensile strength and shear strength of the material. Detailed implementation mode

[0037] The embodiment of the present application discloses a preparation method of a high-density carbon-carbon composite material. The raw materials used in the present application can be obtained from commercially available raw materials except as otherwise specified. The following further details the present application in combination with the embodiments:

[0038] Raw material description: The carbon fiber material includes carbon fiber cloth and carbon fiber mesh tire, and the models include one or more of T300, T700, T800, T900, T1000, T1100, etc. T300 carbon fiber cloth is used in the present application. In the present application, the carbon fiber cloth is unidirectionally laminated after being impregnated with the slurry. The fineness of the nano-silica powder is 50nm, the thickness of the graphene oxide is 1nm, the silane coupling agent is KH-550 (CAS No.: 919-30-2), hydroquinone (CAS No.: 123-31-9), octaphenylaminocage silsesquioxane (CAS No.: 518359-82-5), formaldehyde (CAS No.: 50-00-0), p-toluenesulfonic acid (CAS No.: 104-15-4), maleic anhydride (CAS No.: 108-31-6), 2,6-diaminopyridine (CAS No.: 141-86-6), phenolic resin (CAS No.: 9003-35-4), and the molecular weight is 1500.

[0039] Example 1

[0040] Preparation of auxiliary materials

[0041] Disperse 0.1 kg of graphene oxide into deionized water. After ultrasonic treatment for 1 h, a graphene oxide dispersion is obtained; add 1 kg of nano-silicon powder into absolute ethanol. After ultrasonic treatment for 30 min, add 0.05 kg of silane coupling agent, and stir and react at 80 °C at a speed of 300 rpm for 2 h to obtain a modified nano-silicon powder dispersion; add the graphene oxide dispersion into the modified nano-silicon powder dispersion, adjust the pH to 5 with 1 mol / L hydrochloric acid aqueous solution, after ultrasonic treatment for 30 min, stir and react at a speed of 500 rpm for 2 h, and after centrifugation, wash three times with deionized water and absolute ethanol respectively, and dry in vacuum at 60 °C to obtain auxiliary materials.

[0042] Prepare a gelling material

[0043] Mix 2.91 kg of hydroquinone and 8 kg of octaphenylaminocage silsesquioxane and disperse them into 20 L of ethanol. Heat up to 60 °C and add 2.51 kg of formaldehyde. The form of formaldehyde addition is an aqueous solution of formaldehyde with a concentration of 37%. Add it within 2 h. After adding, add 10 g of p-toluenesulfonic acid, heat up to 120 °C and stir and react at a speed of 300 rpm for 5 h. After cooling to below 30 °C, wash the product with deionized water, separate to obtain the organic phase, concentrate the organic phase by rotary evaporation at 80 °C, pour the concentrated organic phase into hexane for precipitation, collect the precipitate, and dry the precipitate at 80 °C to obtain benzoxazine-modified silsesquioxane.

[0044] Mix 19.61 kg of maleic anhydride and 10.91 g of 2,6-diaminopyridine and disperse them into 50 L of N,N-dimethylformamide. Under nitrogen protection, stir at a speed of 200 rpm for 15 min to obtain a mixed solution; heat up the mixed solution to 120 °C at a heating rate of 2 °C / min, stir and react at a speed of 200 rpm for 6 h. After cooling to below 30 °C, obtain a product solution. Pour the product solution into 10 times the volume of deionized water, separate to obtain a precipitated product, wash the precipitated product with deionized water, and dry the washed precipitated product in vacuum at 80 °C to obtain bismaleimide.

[0045] Mix 16.22 kg of bismaleimide, 12.16 kg of phenolic resin and 1.62 kg of benzoxazine-modified silsesquioxane, and stir at a speed of 300 rpm for 30 min under nitrogen protection to obtain a mixture; heat up the mixture to 160 °C at a speed of 2 °C / min and stir and react at a speed of 300 rpm for 6 h. After cooling to below 30 °C, discharge to obtain a gelling material.

[0046] Prepare a high-density carbon-carbon composite material

[0047] (1)Mixing: Mix and disperse the gelling material and auxiliary materials into N,N-dimethylformamide. The addition amount of N,N-dimethylformamide is adjusted according to the viscosity state, and stirred at a speed of 200 rpm for 1 h to obtain a slurry; Immerse the carbon fiber material in the slurry, take it out after 10 min of immersion to obtain a carbon fiber prepreg. The mass ratio of the carbon fiber material, gelling material and auxiliary materials is 0.2:1:0.05;

[0048] (2)Pre-forming: Stack the carbon fiber prepregs and perform pre-pressing in a hot press. The pre-pressing temperature is 50 °C, the pre-pressing pressure is 5 MPa, and the pre-pressing time is 4 h to obtain a pre-pressed carbon fiber material;

[0049] (3)Final forming: Hot press the pre-pressed carbon fiber material. The hot pressing temperature is 200 °C, the hot pressing pressure is 30 MPa, and the hot pressing time is 5 h to obtain a carbon fiber semi-finished product;

[0050] (4)Impregnation: Prepare an impregnating agent from the gelling material. The mass ratio of the gelling material, butyl glycidyl ether and allylcresol in the impregnating agent is 1:0.1:0.1. Vacuum pressure impregnate the carbon fiber semi-finished product in the impregnating agent. The impregnation temperature is 150 °C, the impregnation pressure is 8 MPa, and the impregnation time is 5 h. After impregnation, maintain the pressure and heat up to 300 °C for curing to obtain an impregnated semi-finished product. The impregnation step can be repeated 1 - 10 times;

[0051] (5)Carbonization: Carbonize the impregnated semi-finished product in an argon atmosphere. The carbonization temperature is 600 °C and the carbonization time is 36 h to obtain a carbonized material. The carbonization step can be repeated 2 - 3 times;

[0052] (6)Graphitization: Graphitize the carbonized material in an argon atmosphere. The graphitization temperature is 1800 °C, the graphitization time is 8 h, and the heating rate is 1 °C / min to obtain a high-density carbon-carbon composite material.

[0053] Example 2

[0054] Disperse 0.1 kg of graphene oxide into deionized water, and after ultrasonic treatment for 1 h, obtain a graphene oxide dispersion; Add 1 kg of nano-silicon powder into absolute ethanol, after ultrasonic treatment for 30 min, add 0.05 kg of silane coupling agent, and stir and react at 80 °C at a speed of 300 rpm for 2 h to obtain a modified nano-silicon powder dispersion; Add the graphene oxide dispersion into the modified nano-silicon powder dispersion, adjust the pH to 5 with 1 mol / L hydrochloric acid aqueous solution, after ultrasonic treatment for 30 min, stir and react at a speed of 500 rpm for 2 h, and after centrifugation, wash three times with deionized water and absolute ethanol respectively, and dry in vacuum at 60 °C to obtain auxiliary materials.

[0055] Preparation of gelling material

[0056] 2.91 kg of hydroquinone and 8 kg of octaphenylaminocage silsesquioxane were mixed and dispersed in 20 L of ethanol. The temperature was raised to 60 °C, and 2.51 kg of formaldehyde was added. The formaldehyde was added in the form of a 37% aqueous formaldehyde solution and was added within 2 h. After the addition, 10 g of p-toluenesulfonic acid was added, and the temperature was raised to 120 °C and stirred at a speed of 300 rpm for 5 h. After cooling to below 30 °C, the product was washed with deionized water, and the organic phase was separated by liquid separation. The organic phase was concentrated by rotary evaporation at 80 °C, and the concentrated organic phase was poured into hexane for precipitation. The precipitate was collected and dried at 80 °C to obtain benzoxazine-modified silsesquioxane.

[0057] 19.61 kg of maleic anhydride and 10.91 g of 2,6-diaminopyridine were mixed and dispersed in 50 L of N,N-dimethylformamide. Under nitrogen protection, it was stirred at a speed of 200 rpm for 15 min to obtain a mixed solution. The mixed solution was heated to 120 °C at a heating rate of 2 °C / min and stirred at a speed of 200 rpm for 6 h. After cooling to below 30 °C, a product solution was obtained. The product solution was poured into 10 times the volume of deionized water, and the precipitated product was separated. The precipitated product was washed with deionized water and vacuum dried at 80 °C to obtain bismaleimide.

[0058] 15.38 kg of bismaleimide, 11.54 kg of phenolic resin, and 3.08 kg of benzoxazine-modified silsesquioxane were mixed. Under nitrogen protection, it was stirred at a speed of 300 rpm for 30 min to obtain a mixed material. The mixed material was heated to 160 °C at a speed of 2 °C / min and stirred at a speed of 300 rpm for 6 h. After cooling to below 30 °C, it was discharged to obtain a gelling material.

[0059] Preparation of high-density carbon-carbon composite material

[0060] (1) Mixing: The gelling material and auxiliary materials were mixed and dispersed in N,N-dimethylformamide. The addition amount of N,N-dimethylformamide was adjusted according to the viscosity state, and it was stirred at a speed of 200 rpm for 1 h to obtain a slurry. The carbon fiber material was impregnated in the slurry. After impregnation for 10 min, it was taken out to obtain a carbon fiber prepreg. The mass ratio of the carbon fiber material, gelling material, and auxiliary materials was 0.6:1:0.3.

[0061] (2) Preforming: The carbon fiber prepregs were laminated and pre-pressed in a hot press at a pre-pressing temperature of 150 °C, a pre-pressing pressure of 2 MPa, and a pre-pressing time of 1 h to obtain a pre-pressed carbon fiber material.

[0062] (3) Final forming: The pre-pressed carbon fiber material was hot-pressed into shape at a hot-pressing temperature of 600 °C, a hot-pressing pressure of 5 MPa, and a hot-pressing time of 3 h to obtain a carbon fiber semi-finished product.

[0063] (4) Impregnation: Prepare an impregnating agent from a gelling material. The mass ratio of the gelling material, butyl glycidyl ether, and allylcresol in the impregnating agent is 1:0.3:0.1. Vacuum-pressure impregnate the semi-finished carbon fiber in the impregnating agent at an impregnation temperature of 350 °C, an impregnation pressure of 2 MPa, and an impregnation time of 2 h. After impregnation, maintain the pressure and raise the temperature to 500 °C for curing to obtain the impregnated semi-finished product. The impregnation step can be repeated 1 - 10 times;

[0064] (5) Carbonization: Carbonize the impregnated semi-finished product in an argon atmosphere at a carbonization temperature of 900 °C and a carbonization time of 10 h to obtain a carbonized material. The carbonization step can be repeated 2 - 3 times;

[0065] (6) Graphitization: Graphitize the carbonized material in an argon atmosphere at a graphitization temperature of 3000 °C, a graphitization time of 1 h, and a heating rate of 15 °C / min to obtain a high-density carbon-carbon composite material.

[0066] Example 3

[0067] Disperse 0.1 kg of graphene oxide in deionized water. After ultrasonic treatment for 1 h, obtain a graphene oxide dispersion; add 1 kg of nano-silicon powder to anhydrous ethanol. After ultrasonic treatment for 30 min, add 0.05 kg of silane coupling agent and stir and react at 80 °C at a speed of 300 rpm for 2 h to obtain a modified nano-silicon powder dispersion; add the graphene oxide dispersion to the modified nano-silicon powder dispersion, adjust the pH to 5 using a 1 mol / L hydrochloric acid aqueous solution, ultrasonic treat for 30 min, stir and react at a speed of 500 rpm for 2 h, and after centrifugation, wash three times with deionized water and anhydrous ethanol respectively, and dry in vacuum at 60 °C to obtain an auxiliary material.

[0068] Preparation of gelling material

[0069] Mix 2.91 kg of hydroquinone and 8 kg of octaphenylaminocage silsesquioxane and disperse them in 20 L of ethanol. Raise the temperature to 60 °C and add 2.51 kg of formaldehyde. The formaldehyde is added in the form of a 37% formaldehyde aqueous solution and is added within 2 h. After adding, add 10 g of p-toluenesulfonic acid, raise the temperature to 120 °C and stir and react at a speed of 300 rpm for 5 h. After cooling to below 30 °C, wash the product with deionized water, separate the organic phase by liquid separation, rotary evaporate and concentrate the organic phase at 80 °C, pour the concentrated organic phase into hexane for precipitation, collect the precipitate, and dry the precipitate at 80 °C to obtain benzoxazine-modified silsesquioxane.

[0070] 19.61 kg of maleic anhydride and 10.91 g of 2,6-diaminopyridine were mixed and dispersed in 50 L of N,N-dimethylformamide. Under nitrogen protection, the mixture was stirred at a speed of 200 rpm for 15 min to obtain a mixed solution. The mixed solution was heated to 120 °C at a heating rate of 2 °C / min and stirred at a speed of 200 rpm for 6 h. After cooling to below 30 °C, a product solution was obtained. The product solution was poured into 10 times its volume of deionized water, and the precipitated product was separated. The precipitated product was washed with deionized water and then dried in vacuo at 80 °C to obtain bismaleimide.

[0071] 15.79 kg of bismaleimide, 11.84 kg of phenolic resin, and 2.37 kg of benzoxazine-modified silsesquioxane were mixed. Under nitrogen protection, the mixture was stirred at a speed of 300 rpm for 30 min to obtain a mixture. The mixture was heated to 160 °C at a speed of 2 °C / min and stirred at a speed of 300 rpm for 6 h. After cooling to below 30 °C, it was discharged to obtain a gelled material.

[0072] Preparation of high-density carbon-carbon composite materials

[0073] (1) Mixing: The gelled material and auxiliary materials were mixed and dispersed in N,N-dimethylformamide. The addition amount of N,N-dimethylformamide was adjusted according to the viscosity state, and the mixture was stirred at a speed of 200 rpm for 1 h to obtain a slurry. The carbon fiber material was impregnated in the slurry. After 10 min of impregnation, it was taken out to obtain a carbon fiber prepreg. The mass ratio of the carbon fiber material, gelled material, and auxiliary materials was 0.4:1:0.15.

[0074] (2) Preforming: The carbon fiber prepregs were stacked and pre-pressed in a hot press. The pre-pressing temperature was 100 °C, the pre-pressing pressure was 3.5 MPa, and the pre-pressing time was 2.5 h to obtain a pre-pressed carbon fiber material.

[0075] (3) Final forming: The pre-pressed carbon fiber material was hot-pressed. The hot-pressing temperature was 400 °C, the hot-pressing pressure was 17.5 MPa, and the hot-pressing time was 4 h to obtain a carbon fiber semi-finished product.

[0076] (4) Impregnation: The gelled material was formulated into an impregnating agent. The mass ratio of the gelled material, butyl glycidyl ether, and allyl cresol in the impregnating agent was 1:0.2:0.1. The carbon fiber semi-finished product was vacuum pressure-impregnated in the impregnating agent. The impregnation temperature was 250 °C, the impregnation pressure was 5 MPa, and the impregnation time was 3.5 h. After impregnation, the pressure was maintained and the temperature was raised to 400 °C for curing to obtain an impregnated semi-finished product. The impregnation step can be repeated 1 - 10 times.

[0077] (5) Carbonization: The impregnated semi-finished product is carbonized under an argon atmosphere at a carbonization temperature of 750 °C for 23 h to obtain a carbonized material. The carbonization step can be repeated 2 - 3 times;

[0078] (6) Graphitization: The carbonized material is graphitized under an argon atmosphere at a graphitization temperature of 2400 °C for 4.5 h with a heating rate of 8 °C / min to obtain a high-density carbon-carbon composite material.

[0079] Example 4

[0080] Example 4 is based on Example 3. The difference between Example 4 and Example 3 is only that in Example 4, the mass ratio of carbon fiber material, cementitious material, and auxiliary material is 0.15:1:0.03.

[0081] Example 5

[0082] Example 5 is based on Example 3. The difference between Example 5 and Example 3 is only that in Example 5, the mass ratio of carbon fiber material, cementitious material, and auxiliary material is 0.7:1:0.3.

[0083] Example 6

[0084] Example 6 is based on Example 3. The difference between Example 6 and Example 3 is only that in Example 6, the dosage of bismaleimide is 16.67 kg, the dosage of phenolic resin is 12.5 kg, and the dosage of benzoxazine-modified silsesquioxane is 0.83 kg.

[0085] Example 7

[0086] Example 7 is based on Example 3. The difference between Example 7 and Example 3 is only that in Example 7, the dosage of bismaleimide is 15 kg, the dosage of phenolic resin is 11.25 kg, and the dosage of benzoxazine-modified silsesquioxane is 3.75 kg.

[0087] Example 8

[0088] Example 8 is based on Example 3. The difference between Example 8 and Example 3 is only that in Example 8, bismaleimide is replaced by maleimide.

[0089] Example 9

[0090] Example 9 is based on Example 3. The difference between Example 9 and Example 3 is only that in Example 9, benzoxazine-modified silsesquioxane is replaced by octaphenylamino cage silsesquioxane.

[0091] Example 10

[0092] Example 10 is based on Example 3. The only difference between Example 10 and Example 3 is that in Example 10, the mass ratio of the gelling material, butyl glycidyl ether, and allylcresol in the impregnating agent is 1:0.05:0.1.

[0093] Example 11

[0094] Example 11 is based on Example 3. The only difference between Example 11 and Example 3 is that in Example 11, the mass ratio of the gelling material, butyl glycidyl ether, and allylcresol in the impregnating agent is 1:0.4:0.1.

[0095] Example 12

[0096] Example 12 is based on Example 3. The only difference between Example 12 and Example 3 is that allylcresol is not added in Example 12.

[0097] Comparative Example 1

[0098] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that in Comparative Example 1, the gelling material is replaced with phenolic resin.

[0099] Comparative Example 2

[0100] Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that in Comparative Example 2, the auxiliary material is replaced with silica powder.

[0101] Performance Detection Test

[0102] (1) Density test: The mass and volume of the test specimens are measured and recorded, and the density of the test specimens is calculated. Each test specimen is tested three times, and the average value is taken after measurement. The results are recorded in Table 1.

[0103] (2) Select "GB / T 33501-2017 Test Method for Tensile Properties of Carbon-Carbon Composites" and "GB / T 40388-2021 Test Method for Shear Strength of Carbon-Carbon Composites" as the standards to test the transverse and longitudinal tensile strengths and interlaminar shear strength of the test specimens. Each test specimen is tested three times, and the average value is taken after measurement. The results are recorded in Table 1.

[0104] (3) Thermal conductivity test: The thermal conductivity of the test specimens is measured and calculated using a German NETZSCH LFA457 laser flash analyzer. The thermal conductivities of the test specimens parallel to the transverse and longitudinal directions are respectively tested and calculated. Each test specimen is tested three times, and the average value is taken after measurement. The results are recorded in Table 1.

[0105] Table 1 Detection Results of Material Density, Tensile Strength, Shear Strength, and Thermal Conductivity

[0106] As can be seen from Table 1, the density of Examples 1-3 is greater than 1.94 g / cm3, the transverse tensile strength is greater than 115.8 MPa, the longitudinal tensile strength is greater than 1067.8 MPa, the interlaminar shear strength is greater than 32.6 MPa, the transverse thermal conductivity is greater than 142.7 W·m-1·K-1, and the longitudinal thermal conductivity is greater than 765.3 W·m-1·K-1. It can be seen that the carbon-carbon composite material prepared in this application has good density, high thermal conductivity and high strength.

[0107] As can be seen from Table 1, the differences between Examples 4 and 5 and Example 3 are only as follows: in Example 4, the mass ratio of carbon fiber material, gelling material and auxiliary material is 0.15:1:0.03; in Example 5, the mass ratio of carbon fiber material, gelling material and auxiliary material is 0.7:1:0.3. Compared with Example 3, the density, strength and thermal conductivity of Examples 4 and 5 decrease. This is because changing the ratio of carbon fiber material, gelling material and auxiliary material will destroy the structural balance inside the material and increase the defects inside the material, resulting in a decrease in density, strength and thermal conductivity.

[0108] As can be seen from Table 1, the differences between Examples 6 and 7 and Example 3 are only as follows: in Example 6, the mass ratio of bismaleimide, phenolic resin and benzoxazine-modified silsesquioxane is 1:0.75:0.05; in Example 7, the mass ratio of bismaleimide, phenolic resin and benzoxazine-modified silsesquioxane is 1:0.75:0.25. Compared with Example 3, the density, strength and thermal conductivity of Examples 6 and 7 decrease. This is because changing the dosage of benzoxazine-modified silsesquioxane, too much benzoxazine-modified silsesquioxane is prone to agglomeration, resulting in phase separation problems and destroying the stability of the material; too little benzoxazine-modified silsesquioxane leads to a decrease in the enhancement effect and an insignificant improvement in performance, resulting in a decrease in density, strength and thermal conductivity.

[0109] As can be seen from Table 1, the differences between Examples 8 and 9 and Example 3 are only as follows: in Example 8, bismaleimide is replaced by maleimide; in Example 9, benzoxazine-modified silsesquioxane is replaced by octaphenylamino cage silsesquioxane. Compared with Example 3, the density, strength and thermal conductivity of Examples 8 and 9 decrease. This is because when bismaleimide is replaced by maleimide, maleimide is difficult to construct a highly crosslinked branched structure, the pores inside the material increase, the density of the material decreases, and sufficient mechanical support cannot be provided, resulting in a decrease in strength and a decrease in thermal conductivity; when benzoxazine-modified silsesquioxane is replaced by octaphenylamino cage silsesquioxane, the introduction of the benzoxazine structure is lacking, the intermolecular force decreases, and the thermal conductivity becomes poor, resulting in a decrease in density, strength and thermal conductivity.

[0110] As can be seen from Table 1, the differences between Examples 10, 11, 12 and Example 3 are only as follows: in Example 10, the mass ratio of the gelling material, butyl glycidyl ether and allyl cresol in the impregnating agent is 1:0.05:0.1; in Example 11, the mass ratio of the gelling material, butyl glycidyl ether and allyl cresol in the impregnating agent is 1:0.4:0.1; in Example 12, allyl cresol is not added. Compared with Example 3, the density, strength and thermal conductivity of Examples 10, 11 and 12 are decreased. This is because changing the ratio and components of the components in the impregnating agent will affect the wettability and cross-linking effect of the impregnating agent. After the wettability decreases, the gelling material cannot fully penetrate into the pores to further improve the density and reinforce the structure. The change in the cross-linking density will affect the performance of the structure, resulting in a decrease in density, strength and thermal conductivity.

[0111] As can be seen from Table 1, the difference between Comparative Example 1 and Example 3 is only that: in Comparative Example 1, the gelling material is replaced by phenolic resin. Compared with Example 3, the density, strength and thermal conductivity of Comparative Example 1 are significantly decreased. This is because when the gelling material is replaced by phenolic resin, the synergistic effect of bismaleimide and benzoxazine modified silsesquioxane is lacking, the cross-linking density and intermolecular force of the gelling material are decreased, and the stability of the structure is decreased, resulting in a significant decrease in density, strength and thermal conductivity.

[0112] As can be seen from Table 1, the difference between Comparative Example 2 and Example 3 is only that: in Comparative Example 2, the auxiliary material is replaced by silicon powder. Compared with Example 3, the density, strength and thermal conductivity of Comparative Example 2 are decreased. This is because when the auxiliary material is replaced by silicon powder, the single silicon powder lacks the synergistic effect of graphene oxide and lacks modification treatment, resulting in a decrease in dispersibility, and thus the density, strength and thermal conductivity are decreased.

[0113] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. Through the above description, relevant staff can make various changes and modifications completely within the scope of the technical idea of this application without deviation. The technical scope of this application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a high-density carbon-carbon composite material, characterized in that: The following steps are involved: (1) Mixing: Mixing the gelling material with the auxiliary material to obtain a slurry; impregnating the carbon fiber material into the slurry and taking it out to obtain a carbon fiber prepreg; (2) Preforming: stacking and pre-pressing the carbon fiber prepreg to obtain a pre-pressed carbon fiber material; (3) Final molding: hot pressing the pre-pressed carbon fiber material to obtain a carbon fiber semi-finished product; (4) Impregnation: The gelling material is prepared into an impregnating agent, and the carbon fiber semi-finished product is impregnated in the impregnating agent under pressure. After the impregnation is completed, the pressure is maintained, and the temperature is increased to cure to obtain the impregnated semi-finished product; (5) Carbonization: The semi-finished product after impregnation is carbonized under an inert gas atmosphere to obtain a carbonized material; (6) Graphitization: The carbonized material is graphitized in an inert gas atmosphere to obtain a high-density carbon-carbon composite material.

2. The method for preparing a high-density carbon-carbon composite material according to claim 1, characterized in that: The mass ratio of the carbon fiber material, the gelling material and the auxiliary material is (0.2-0.6):1:(0.05-0.3).

3. The method for preparing a high-density carbon-carbon composite material according to claim 2, characterized in that: The raw materials for preparing the auxiliary material include nano silicon powder, graphene and a silane coupling agent.

4. The method for preparing a high-density carbon-carbon composite material according to claim 2, characterized in that: The raw materials for preparing the gelling material include bismaleimide, phenolic resin and benzoxazine-modified silsesquioxane.

5. The method for preparing a high-density carbon-carbon composite material according to claim 4, characterized in that: The mass ratio of the bismaleimide, the phenolic resin and the benzoxazine-modified silsesquioxane is 1:0.75:(0.1-0.2).

6. The method for preparing a high-density carbon-carbon composite material according to claim 5, characterized in that: The raw materials for preparing the bismaleimide include maleic anhydride and 2,6-diaminopyridine.

7. The method for preparing a high-density carbon-carbon composite material according to claim 5, characterized in that: The raw materials for preparing the benzoxazine-modified silsesquioxane include octaphenylamino cage-type silsesquioxane, hydroquinone and formaldehyde.

8. The method for preparing a high-density carbon-carbon composite material according to claim 7, characterized in that: The benzoxazine-modified silsesquioxane is prepared by the following steps: The hydroquinone and octaphenylamino cage-type silsesquioxane are mixed and dispersed in ethanol, and formaldehyde is added after heating. After the addition is completed, p-toluenesulfonic acid is added, and the temperature is raised and stirred to react. After cooling, the product is washed with water, and the liquid is separated to obtain an organic phase, the organic phase is concentrated by rotary evaporation, and the concentrated organic phase is poured into hexane for precipitation, the precipitate is collected, and the precipitate is dried to obtain benzoxazine-modified silsesquioxane.

9. The method for preparing a high-density carbon-carbon composite material according to claim 5, characterized in that: The impregnating agent includes a gelling material, butyl glycidyl ether and allyl cresol.

10. The method for preparing a high-density carbon-carbon composite material according to claim 9, characterized in that: The mass ratio of the gelling material, butyl glycidyl ether and allyl cresol is 1:(0.1-0.3):0.1.

Images