Carbon-carbon composite high-heat-resistance foaming material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of carbon-carbon composite thermal insulation materials, in particular to a carbon-carbon composite high-thermal-resistance foaming material as well as a preparation method and application thereof. The foaming material is prepared from a composite blank through heat treatment. The composite blank is prepared by taking alkali-etched polyurethane sponge as a template, taking polyamide acid and water-borne epoxy resin as a carbon skeleton, taking water-borne polyurethane as a filling skeleton, taking ammonium bicarbonate as a foaming agent, taking graphene oxide modified carbon fibers as a reinforcing phase and taking carbon aerogel as a heat insulation reinforcing phase through template dipping and curing molding. The carbon-carbon composite high-thermal-resistance foaming material has high strength and low thermal conductivity, can be directly used for preparing high-performance thermal insulation components, and is adaptive to a high-temperature treatment furnace.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon-carbon composite thermal insulation materials, in particular to a carbon-carbon composite high-thermal-resistance foaming material and a preparation method and application thereof. BACKGROUND

[0002] In some high-temperature-resistant material applications, the material is required to have high thermal resistance and high strength, and the temperature in the application environment is also very high. Most high-temperature-resistant materials are difficult to be preserved under such temperature conditions.

[0003] CN113321844B discloses a graphene / polyimide composite foam wave-absorbing material with an oriented pore structure and a preparation method thereof, and belongs to the technical field of porous composite foam wave-absorbing materials and preparation thereof. The graphene / polyimide composite foam material with an oriented layered pore structure is obtained by compounding graphene oxide and polyamide acid, through a bidirectional ice template method, vacuum freeze-drying and thermal imidization treatment process. Although the technical solution for obtaining a foam material by using carbon materials is disclosed, the polyimide in the above-mentioned material is used as the final use phase, and the temperature limit of the polyimide limits the application of the material in a high-temperature environment.

[0004] Therefore, the prior art is committed to preparing porous materials by a template method to balance thermal insulation and other properties. However, when pursuing application in a high-temperature extreme environment, these material systems expose their inherent limitations. More importantly, the prior art solutions are generally difficult to effectively balance the three key performance indicators of low thermal conductivity, high strength and high-temperature resistance. The microstructure designed to achieve low thermal conductivity often sacrifices the intrinsic strength of the material; and simply pursuing temperature resistance limits the selection of the matrix material. Therefore, how to make the foaming material both resistant to high temperature in the nature of the material and simultaneously achieve excellent thermal insulation performance and structural strength sufficient to meet the actual application requirements is a technical problem to be solved in the field. SUMMARY

[0005] To solve the above technical problems, the present application provides a carbon-carbon composite high-thermal-resistance foaming material, which is prepared from a composite embryo by heat treatment. The composite embryo is prepared by using alkali-etched polyurethane sponge as a template, polyamide acid and water-based epoxy resin as carbon skeletons, water-based polyurethane as a filling skeleton, ammonium bicarbonate as a foaming agent, and graphene oxide modified carbon fiber as a reinforcing phase, and carbon aerogel as a thermal insulation reinforcing phase, and then being solidified and formed after template impregnation.

[0006] Further, the density of the carbon-carbon composite high-thermal-resistance foaming material is 0.16-0.22 g / cm 3 , the compressive strength is 0.49-0.63 MPa, and the thermal conductivity at 1000℃ is 0.38-0.53 W / (m·K).

[0007] Further, the composite body has a three-dimensional crosslinked network structure.

[0008] Further, the temperature of the heat treatment is 200-1300℃.

[0009] Further, the number of times of the heat treatment is one or two.

[0010] Further, when the number of times of the heat treatment is two: the first heat treatment is thermal decomposition, and the temperature is 200-300℃; the second heat treatment is high-temperature treatment, and the temperature is 600-1300℃.

[0011] Further, the inner diameter of the pores of the polyurethane sponge is 100-500μm.

[0012] Further, the alkaline substance used in the alkaline etching is an inorganic base.

[0013] Further, the inorganic base includes, but is not limited to, potassium hydroxide, sodium hydroxide.

[0014] Further, the inorganic base is preferably sodium hydroxide.

[0015] Further, the molecular weight (Mw) of the polyurethane sponge is 100,000-300,000g / mol, and the porosity is 75-90%.

[0016] Further, the molecular weight of the polyamide acid (PAAc) is 100,000-200,000g / mol, and the molecular structure contains repeating amide groups (-CONH-), and the carboxyl content is 4.8-5.5mmol / g; the polyamide acid is used in the form of a PAAc solution, the solid content of the PAAc solution is 30-35wt.%, the solvent system thereof is composed of deionized water (30%-40% of the total mass of the solvent) and a cosolvent N-methyl pyrrolidone (NMP, 60%-70% of the total mass of the solvent), and the viscosity at 25℃ is 1500-2500mPa·s.

[0017] Further, the epoxy equivalent weight (EEW) of the water-based epoxy resin is 480-520g / eq; the water-based epoxy resin is used in the form of a water-based dispersion, the solid content thereof is 40-45wt.%, and the viscosity at 25℃ is 800-1500mPa·s.

[0018] Further, the waterborne epoxy resin uses triethylene tetramine (TETA) as a curing agent, the molecular weight of the triethylene tetramine (TETA) is 146.23 g / mol, the amine hydrogen equivalent is 36.5 g / eq, the purity is greater than or equal to 98 wt.%, and the impurity content is less than 0.1 wt.%.

[0019] Further, the waterborne polyurethane (WPU) solution has a solid content of 30-45 wt.%, the solvent is composed of deionized water (90%-95%) and a cosolvent N-methyl pyrrolidone (NMP, 5%-10%), and the viscosity at 25 DEG C is 300-800 mPa s; the hydroxyl value of the waterborne polyurethane resin is 50-150 mg KOH / g, the hydrophilic group is a carboxylic acid type, and it is a hydroxyl end-capped type.

[0020] Further, the ammonium bicarbonate has a molecular weight of 79.06 g / mol and a purity of greater than or equal to 99 wt.%.

[0021] Further, the graphene oxide (GO) has a sheet diameter of 8-15 pm, wherein the proportion of single-layer graphene oxide is not less than 90%, and the thickness is 0.9-1.1 nm. The concentration of the graphene oxide (GO) dispersion liquid is 0.7-1.0 wt.%, and the dispersion medium of the graphene oxide (GO) dispersion liquid is deionized water.

[0022] Further, the carbon fiber is a chopped carbon fiber.

[0023] Further, the chopped carbon fiber has a filament diameter of 7-10 pm, a length of 1-3 mm, a tensile modulus of greater than or equal to 200 GPa, a tensile strength of greater than or equal to 3000 MPa, and a carbon content of greater than or equal to 96%.

[0024] Further, the carbon aerogel has a particle size of 8-12 pm, a density of 0.1-0.2 g / cm 3 , a porosity of greater than or equal to 90%, and a specific surface area of greater than or equal to 600 m 2 / g, wherein the proportion of carbon aerogel with a pore size of 20-50 nm is greater than or equal to 90%.

[0025] The present application provides a preparation method of the above-mentioned carbon-carbon composite high-thermal-resistance foaming material, which comprises template pretreatment, composite slurry preparation, template impregnation and solidification forming, and heat treatment.

[0026] Further, the preparation method comprises the following specific steps: Step 1, template pretreatment: etching polyurethane sponge with an alkali solution to obtain a pretreated template; the alkali solution is used to hydrolyze the polyurethane ester bond to generate hydrophilic amino and carboxyl groups, thereby improving the surface energy of the template. Step 2, Preparation of composite slurry: This includes pre-dispersion of graphene oxide (GO) and carbon fiber, matrix mixing, and introduction of functional components to prepare the composite slurry; Step 3, Template Impregnation and Curing: including vacuum impregnation and step-by-step curing; Step 4: Template removal and pre-oxidation, i.e., thermal decomposition; Step 5: After high-temperature treatment of the composite preform, a carbon-carbon composite high heat-resistant foam material is obtained.

[0027] Furthermore, the concentration of inorganic alkali in the alkaline solution described in step 1 is 5 wt.%.

[0028] Furthermore, the etching temperature in step 1 is 60°C, and the etching time is 30-45 minutes.

[0029] Furthermore, in step 1, before etching the polyurethane sponge with an alkaline solution, the polyurethane sponge is first ultrasonically cleaned with deionized water. Used to break the adhesion between impurities and sponge, remove surface grease / particles, and improve the wettability of composite slurry.

[0030] Furthermore, the ultrasonic power is 40 kHz, and the ultrasonic duration is 10-30 min.

[0031] Furthermore, in step 1, after etching is completed, the pretreated template needs to be washed and dried.

[0032] Furthermore, the water washing and drying process involves washing until the pH of the filtrate reaches 7, drying at 60°C for 2 hours; Used to remove residual alkaline solution and prevent pH imbalance in composite slurry.

[0033] Furthermore, step 2 specifically involves: Step 2-1, Graphene Oxide (GO)-Carbon Fiber Pre-dispersion: The graphene oxide (GO) dispersion is mixed with carbon fiber, and after stirring and ultrasonic treatment, a uniform and stable pre-dispersion is obtained. The ultrasound is used to peel off the aggregates of graphene oxide (GO), drive the graphene oxide (GO) to adsorb onto the fiber surface, and stir to prevent carbon fiber sedimentation. Step 2-2, Matrix Mixing: Add polyamic acid (PAAc) solution and waterborne polyurethane (WPU) solution to the pre-dispersion solution in Step 2-1, and stir to obtain a matrix mixture; Stirring conditions promote PAAc chain segment movement and form a hydrogen bond network with WPU hydroxyl groups; inhibit premature gelation of PAAc, and hydrogen bond crosslinking enhances the thixotropy of the slurry and prevents solid phase sedimentation. Steps 2-3: Introduction of functional components.

[0034] Furthermore, the concentration of the graphene oxide (GO) dispersion in step 2-1 is 0.7-1.0 wt.%, and the solvent is deionized water.

[0035] Furthermore, the diameter of the carbon fiber mentioned in step 2-1 is 7-10 μm.

[0036] Further, the mass ratio of the graphene oxide (GO) dispersion to the carbon fiber in step 2-1 is (1.5-2):1.

[0037] Furthermore, the stirring described in step 2-1 is magnetic stirring or mechanical stirring.

[0038] Furthermore, the stirring speed is 300-500 rpm, and the stirring time is 10-30 min.

[0039] Furthermore, the ultrasonic power in step 2-1 is 250-350W, and the duration is 20-40min.

[0040] Furthermore, the stirring conditions described in step 2-2 are: 50°C water bath, stirring at 300 rpm for 1 hour.

[0041] Further, the mass ratio of the pre-dispersed liquid, the PAAc solution, and the waterborne polyurethane (WPU) solution in step 2-2 is (0.1-0.2):(1-1.5):(1-1.2).

[0042] Furthermore, steps 2-3 are as follows: 1) Premix waterborne epoxy resin with triethylenetetramine (TETA) at a mass ratio of (8-10):1, and stir at 300-500 rpm for 5-8 min to obtain the activated epoxy resin-TETA mixture. Triethylenetetramine (TETA) undergoes ring-opening polymerization with epoxy groups to form a three-dimensional cross-linked network, thereby improving the strength of the preform.

[0043] 2) Add the activated epoxy resin-TETA mixture, ammonium bicarbonate, and carbon aerogel powder to the matrix mixture in sequence, wherein the mass ratio of matrix mixture: activated epoxy resin-TETA mixture: ammonium bicarbonate: carbon aerogel powder is (12-15): (4-8): (1-2): (0.5-1). Ammonium bicarbonate begins to decompose at 60-100℃ and decomposes violently at 200℃, decomposing into ammonia, carbon dioxide and water, thus creating pores during the pre-oxidation stage. Carbon aerogel powder, as a carbon material with a three-dimensional nanoporous network, serves to introduce a pre-fabricated porous carbon network, further enhancing the thermal insulation performance of carbon foam.

[0044] 3) Stir at 200 rpm for 30 minutes to ensure uniform dispersion.

[0045] 4) Add 0.5-2wt.% of deionized water to the slurry in batches, stirring at 300rpm for 5 minutes each time. After mixing evenly, measure the viscosity using a rotational viscometer. The final slurry viscosity should be controlled at 3000-5000mPa•s.

[0046] Among them, TETA pre-activation improves cross-linking efficiency; low-speed stirring prevents premature decomposition of ammonium bicarbonate and destruction of carbon aerogel structure; and low viscosity ensures deep penetration of the sponge.

[0047] Furthermore, step 3 specifically involves: Step 3-1, Vacuum Impregnation: Immerse the pre-treated template in the slurry, ensuring that the slurry surface completely covers the template and is more than 1 cm above its top surface. Then place the entire impregnation system in a vacuum environment, evacuate to -0.09 MPa and maintain for 40-60 minutes. Step 3-2, Step-by-step curing: 1) Dry at 60℃ with forced air for 5 hours: Used to evaporate and remove free water, preventing rapid evaporation of water from causing cracks in the pore walls; 2) Heat to 120℃ and cure for 3 hours to ensure that the waterborne epoxy resin is fully crosslinked and cured under the action of TETA, and the WPU crosslinking is completed simultaneously to obtain a cured preform; The hydroxyl groups on the WPU molecular chain undergo ring-opening polymerization with the epoxy groups of the epoxy resin under TETA catalysis. At the same time, the hydroxyl groups of WPU and the carboxyl groups of PAAc form strong hydrogen bonds, together forming a three-dimensional cross-linked network.

[0048] Further, step 4 specifically involves: placing the cured preform in a muffle furnace and performing a programmed temperature rise heat treatment in an air atmosphere: raising the temperature from room temperature to 200°C at a rate of 3-10°C / min, and holding it at 200°C for 2-3 hours. At this time, ammonium bicarbonate begins to decompose and create pores, and PAAc begins to imidize. Subsequently, the temperature is raised to 300°C at a rate of 5-10°C / min, and held at 300°C for 2-3 hours to obtain a composite preform. At this time, the template PU is completely removed, and PAAc accelerates ring closure and fully imidizes to convert into polyimide (PI). Finally, the preform is removed after cooling to room temperature, completing the template removal and pre-oxidation. Further, step 5 specifically involves: placing the composite preform in a tube furnace, introducing nitrogen gas at a flow rate of 50 mL / min, raising the temperature from room temperature to 600°C in a nitrogen atmosphere, holding it at 600°C for 1-2 hours, then heating it to 1300°C, maintaining it at 1300°C for 2-3 hours, and finally allowing it to cool naturally to room temperature to obtain a carbon-carbon composite high heat-resistant foamed material.

[0049] At 600℃, polyimide (PI) undergoes thermal decomposition, the main chain breaks, and heteroatoms (such as O, N, and H) escape as small molecule gases. Subsequently, the carbon layers rearrange at high temperatures, and graphite microcrystals grow. The carbon fibers and the PI-derived carbon skeleton form a strong physicochemical bond. The carbon aerogel is structurally stable at high temperatures, further enhancing the thermal insulation performance of the material.

[0050] The present invention also provides a thermal insulation component comprising the above-mentioned carbon-carbon composite high thermal resistance foam material.

[0051] The present invention also provides a high-temperature treatment furnace, which includes the above-mentioned heat-insulating component.

[0052] Furthermore, the high-temperature processing furnace is selected from any one of a single-crystal silicon furnace, a sintering furnace, an ingot casting furnace, or a chemical vapor deposition furnace.

[0053] The beneficial effects of this invention are as follows: The carbon-carbon composite high thermal resistance foam material, its preparation method, and its application of the present invention achieve multi-dimensional performance breakthroughs through raw material ratio optimization and process innovation. The core beneficial effects are as follows: 1. Achieving a synergistic balance between high-temperature resistance and key performance: The material is based on a carbon-carbon composite system, relying on the high-temperature resistance of carbon materials (carbon fiber, carbon aerogel, and polymer carbonization derivatives). Through a three-dimensional cross-linked network structure design, it balances high strength and low thermal conductivity, with a density as low as 0.16-0.22 g / cm³. 3 The compressive strength reaches 0.49-0.63MPa, and the thermal conductivity at 1000℃ is only 0.38-0.53W / (m·K), breaking through the bottleneck of existing technologies where it is difficult to achieve all three. 2. Enhanced interfacial bonding and improved material structural stability: Through the modification of carbon fibers with graphene oxide (GO), GO adsorbs onto the carbon fiber surface and is fixed by polymer adhesive. After pyrolysis, the amorphous carbon residue can fill the defects of GO sheets and the micropores on the carbon fiber surface. During the high-temperature process, the carbon atom structure rearrangement and graphite microcrystal growth are further realized, enabling the carbon fiber and carbon skeleton to form a strong physicochemical bond. At the same time, hydroxyl-terminated waterborne polyurethane (WPU) and polyamic acid (PAAc) carboxyl groups form hydrogen bonds for cross-linking. After carbonization, the residual carbon can fill the defects of polyimide (PI) carbon skeleton, significantly improving the interfacial bonding strength and structural integrity of the material, and preventing separation or breakage under stress. 3. Optimize raw material ratios and process design to ensure consistent performance: (1) Using alkali-etched polyurethane sponge as a template, hydrophilic groups are generated by hydrolyzing ester bonds, which greatly improves the wettability and penetration uniformity of the composite slurry and avoids unfilled voids and structural defects. (2) The ammonium bicarbonate foaming agent is precisely matched with the pre-oxidation process temperature to form uniform pores. The carbon aerogel is introduced into the pre-made porous carbon network to block the heat conduction path in two ways. (3) The three-dimensional cross-linked network formed by waterborne epoxy resin and triethylenetetramine (TETA) provides sufficient strength for the green body to support it and prevent it from collapsing during subsequent heat treatment; (4) Vacuum impregnation, step-by-step curing, gradient heat treatment and other processes work together to ensure uniform internal structure of the material, avoid cracking, delamination and other problems, and ensure product performance stability; 4. Expanding high-temperature insulation application scenarios: The material can be directly used to prepare high-performance insulation components, which are suitable for high-temperature processing furnaces, such as single crystal silicon furnaces, sintering furnaces, ingot furnaces or chemical vapor deposition furnaces. Its excellent high temperature resistance, low thermal conductivity and high strength characteristics can effectively reduce heat loss in high-temperature environments, improve equipment operating efficiency and service life, and fill the application gap in the field of high-temperature insulation materials. Detailed Implementation

[0054] Example 1 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material, including template pretreatment, composite slurry preparation, template impregnation and curing, and heat treatment.

[0055] The preparation method includes the following specific steps: Step 1: Template Pretreatment: A polyurethane sponge with a pore inner diameter of 350-500 μm and a porosity of 86% was ultrasonically cleaned using deionized water. The molecular weight (Mw) of the polyurethane sponge was 200,000 g / mol. The ultrasonic power was 40 kHz, and the ultrasonic time was 15 min. The ultrasonically cleaned polyurethane sponge was then etched using a 5 wt.% sodium hydroxide solution at 60°C for 30 min. Afterward, it was washed and dried with water until the pH of the filtrate reached 7. The drying temperature was 60°C for 2 h to obtain the pretreated template. Step 2, Preparation of Composite Slurry: This includes GO-carbon fiber pre-dispersion, matrix mixing, and introduction of functional components to prepare the composite slurry, specifically as follows: Step 2-1, GO-carbon fiber pre-dispersion: 0.7 wt.% graphene oxide (GO) dispersion and short-cut carbon fibers are mixed at a mass ratio of 1.7:1. After magnetic stirring at 300 rpm for 30 min and ultrasonic treatment at 300 W for 30 min, a uniform and stable pre-dispersion is obtained. The graphene oxide (GO) sheet has a diameter range of 8-15 μm, wherein the proportion of monolayer graphene oxide is not less than 90%, and its thickness ranges from 0.9-1.1 nm. The chopped carbon fibers have a single filament diameter ranging from 7-10 μm, a length ranging from 1-3 mm, a tensile modulus ≥200 GPa, a tensile strength ≥3000 MPa, and a carbon content ≥96%. Step 2-2, Matrix Mixing: Add a 30 wt.% polyamic acid (PAAc) solution and a 45 wt.% waterborne polyurethane (WPU) solution to the pre-dispersion solution from Step 2-1, wherein the mass ratio of the pre-dispersion solution, PAAc solution, and WPU solution is 0.2:1:1. After stirring in a 50°C water bath at 300 rpm for 1 hour, a matrix mixture is obtained. The polyamic acid (PAAc) solution is composed of deionized water (30%) and co-solvent N-methylpyrrolidone (NMP, 70%), and has a viscosity of 2000 mPa·s at 25°C; wherein the polyamic acid (PAAc) has a molecular weight of 150,000 g / mol and a carboxyl content of 5 mmol / g. The solvent of the aqueous polyurethane (WPU) solution is composed of deionized water (95%) and co-solvent N-methylpyrrolidone (NMP, 5%), and has a viscosity of 500 mPa·s at 25°C; wherein the hydroxyl value of the aqueous polyurethane (WPU) is 100 mgKOH / g. Steps 2-3, introduction of functional components, specifically: 1) Aqueous epoxy resin and triethylenetetramine (TETA) were premixed at a mass ratio of 9:1 and activated by magnetic stirring at 300 rpm for 8 min to obtain an activated epoxy resin-TETA mixture; wherein the epoxy equivalent (EEW) of the aqueous epoxy resin was 500 g / eq. The aqueous epoxy resin was used in the form of an aqueous dispersion with a solid content of 40 wt.% and a viscosity of 1000 mPa·s at 25°C; the triethylenetetramine (TETA) had a molecular weight of 146.23 g / mol, an amine hydrogen equivalent of 36.5 g / eq, a purity ≥98 wt.%, and an impurity content <0.1 wt.%. 2) Add the following to the matrix mixture in sequence: activated epoxy resin-TETA mixture, ammonium bicarbonate, and carbon aerogel powder, wherein the mass ratio of matrix mixture: activated epoxy resin-TETA mixture: ammonium bicarbonate: carbon aerogel powder is 13:6:1:1. The ammonium bicarbonate has a molecular weight of 79.06 g / mol and a purity of ≥99 wt.%. The carbon aerogel has a particle size range of 8-12 μm and a density of 0.17 g / cm³. 3 Porosity ≥ 90%, specific surface area ≥ 600 m² 2 / g, with ≥90% having a pore size range of 20-50nm; 3) Stir at 200 rpm for 30 minutes to ensure uniform dispersion; 4) The viscosity of the slurry was controlled at 4200 mPa•s by adding 1 wt.% of deionized water in batches, stirring magnetically at 300 rpm for 5 minutes, and measuring the viscosity with a rotational viscometer after mixing evenly. Step 3, Template Impregnation and Curing: including vacuum impregnation and step-by-step curing; Step 3-1, Vacuum Impregnation: Immerse the pre-treated template in the slurry, ensuring that the slurry surface completely covers the sponge and is 1.5cm above its top surface. Then place the entire impregnation system in a vacuum environment, evacuate to -0.09MPa and maintain for 60min. Step 3-2, Step-by-step curing: 1) Drying at 60℃ with forced air for 5 hours: 2) Heat to 120℃ and cure for 3 hours to obtain a cured preform; Step 4: Template removal and pre-oxidation, i.e., thermal decomposition; The cured preform was placed in a muffle furnace and subjected to programmed temperature rise heat treatment in an air atmosphere: the temperature was raised from room temperature to 200°C at a rate of 10°C / min and held at 200°C for 3 hours; then the temperature was raised to 300°C at a rate of 10°C / min and held at 300°C for 3 hours to obtain a composite preform, which was then removed after cooling to room temperature. Step 5: After high-temperature treatment of the composite preform, a carbon-carbon composite high heat-resistant foam material is obtained. Specifically, the composite preform is placed in a tube furnace, nitrogen gas is introduced at a flow rate of 50 mL / min, and the temperature is raised from room temperature to 600℃ and held for 2 hours in a nitrogen atmosphere. Then, it is heated to 1300℃ and held for 2 hours. Finally, it is naturally cooled to room temperature to obtain a carbon-carbon composite high heat-resistant foamed material.

[0056] The density of the carbon-carbon composite high thermal resistance foam material is 0.21 g / cm³. 3 It has a compressive strength of 0.58 MPa and a thermal conductivity of 0.43 W / (m·K) at 1000℃.

[0057] Example 2 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material, including template pretreatment, composite slurry preparation, template impregnation and curing, and heat treatment.

[0058] The preparation method includes the following specific steps: Step 1: Template Pretreatment: A polyurethane sponge with a pore inner diameter range of 100-250 μm and a porosity of 77% was ultrasonically cleaned using deionized water. The molecular weight (Mw) of the polyurethane sponge was 300,000 g / mol. The ultrasonic power was 40 kHz, and the ultrasonic time was 10 min. The ultrasonically cleaned polyurethane sponge was then etched using a 5 wt.% sodium hydroxide solution at a temperature of 60°C for 40 min. Afterward, it was washed and dried with water until the pH of the filtrate reached 7. The drying temperature was 60°C, and the drying time was 2 h to obtain the pretreated template. Step 2, Preparation of Composite Slurry: This includes GO-carbon fiber pre-dispersion, matrix mixing, and introduction of functional components to prepare the composite slurry, specifically as follows: Step 2-1, GO-carbon fiber pre-dispersion: A 1 wt.% graphene oxide (GO) dispersion was mixed with short-cut carbon fibers at a mass ratio of 1.7:1. The mixture was then magnetically stirred at 500 rpm for 20 min and ultrasonically treated at 350 W for 40 min to obtain a uniform and stable pre-dispersion. The graphene oxide (GO) sheet has a diameter range of 8-15 μm, wherein the proportion of monolayer graphene oxide is not less than 90%, and its thickness ranges from 0.9-1.1 nm. The chopped carbon fibers have a single filament diameter ranging from 7-10 μm, a length ranging from 1-3 mm, a tensile modulus ≥200 GPa, a tensile strength ≥3000 MPa, and a carbon content ≥96%. Step 2-2, Matrix Mixing: Add a 30 wt.% polyamic acid (PAAc) solution and a 40 wt.% waterborne polyurethane (WPU) solution to the pre-dispersion solution from Step 2-1, wherein the mass ratio of the pre-dispersion solution, PAAc solution, and WPU solution is 0.1:1.5:1.2. After stirring in a 50°C water bath at 300 rpm for 1 hour, a matrix mixture is obtained. The polyamic acid (PAAc) solution is composed of deionized water (40%) and co-solvent N-methylpyrrolidone (NMP, 60%), and has a viscosity of 2500 mPa·s at 25°C; wherein the polyamic acid (PAAc) has a molecular weight of 100,000 g / mol and a carboxyl content of 5.5 mmol / g. The solvent of the aqueous polyurethane (WPU) solution is composed of deionized water (95%) and co-solvent N-methylpyrrolidone (NMP, 5%), and has a viscosity of 800 mPa·s at 25°C; wherein the hydroxyl value of the aqueous polyurethane (WPU) is 150 mgKOH / g. Steps 2-3, introduction of functional components, specifically: 1) Aqueous epoxy resin and triethylenetetramine (TETA) were premixed at a mass ratio of 8:1 and activated by magnetic stirring at 300 rpm for 8 min to obtain an activated epoxy resin-TETA mixture; wherein the epoxy equivalent (EEW) of the aqueous epoxy resin was 520 g / eq. The aqueous epoxy resin was used in the form of an aqueous dispersion with a solid content of 40 wt.% and a viscosity of 1500 mPa·s at 25°C; the triethylenetetramine (TETA) had a molecular weight of 146.23 g / mol, an amine hydrogen equivalent of 36.5 g / eq, a purity ≥98 wt.%, and an impurity content <0.1 wt.%. 2) Add the following to the matrix mixture in sequence: activated epoxy resin-TETA mixture, ammonium bicarbonate, and carbon aerogel powder, wherein the mass ratio of matrix mixture: activated epoxy resin-TETA mixture: ammonium bicarbonate: carbon aerogel powder is 15:4:2:0.5; The ammonium bicarbonate has a molecular weight of 79.06 g / mol and a purity of ≥99 wt.%. The carbon aerogel has a particle size range of 8-12 μm, a density of 0.17 g / cm³, a porosity of ≥90%, and a specific surface area of ​​≥600 m². 2 / g, with ≥90% having a pore size range of 20-50nm; 3) Stir at 200 rpm for 30 minutes to ensure uniform dispersion; 4) The viscosity of the slurry was controlled at 3100 mPa•s by adding 2 wt.% of deionized water in batches, stirring magnetically at 300 rpm for 5 minutes, and measuring the viscosity with a rotational viscometer after mixing evenly. Step 3, Template Impregnation and Curing: including vacuum impregnation and step-by-step curing; Step 3-1, Vacuum Impregnation: Immerse the pre-treated template in the slurry, ensuring that the slurry surface completely covers the sponge and is 1.5cm above its top surface. Then place the entire impregnation system in a vacuum environment, evacuate to -0.09MPa and maintain for 60min. Step 3-2, Step-by-step curing: 1) Drying at 60℃ with forced air for 5 hours: 2) Heat to 120℃ and cure for 3 hours to obtain a cured preform; Step 4: Template removal and pre-oxidation, i.e., thermal decomposition; The cured preform was placed in a muffle furnace and subjected to programmed temperature rise heat treatment in an air atmosphere: the temperature was raised from room temperature to 200°C at a rate of 10°C / min and held at 200°C for 3 hours; then the temperature was raised to 300°C at a rate of 10°C / min and held at 300°C for 3 hours to obtain a composite preform, which was then removed after cooling to room temperature. Step 5: After high-temperature treatment of the composite preform, a carbon-carbon composite high heat-resistant foam material is obtained. Specifically, the composite preform is placed in a tube furnace, nitrogen gas is introduced at a flow rate of 50 mL / min, and the temperature is raised from room temperature to 600℃ and held for 1 hour in a nitrogen atmosphere. Then it is heated to 1300℃ and held for 2 hours. Finally, it is naturally cooled to room temperature to obtain a carbon-carbon composite high heat-resistant foamed material.

[0059] The density of the carbon-carbon composite high thermal resistance foam material is 0.22 g / cm³. 3 It has a compressive strength of 0.62 MPa and a thermal conductivity of 0.47 W / (m·K) at 1000℃.

[0060] Example 3 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material, including template pretreatment, composite slurry preparation, template impregnation and curing, and heat treatment.

[0061] The preparation method includes the following specific steps: Step 1: Template Pretreatment: A polyurethane sponge with a pore inner diameter of 400-500 μm and a porosity of 89% was ultrasonically cleaned using deionized water. The molecular weight (Mw) of the polyurethane sponge was 100,000 g / mol. The ultrasonic power was 40 kHz, and the ultrasonic time was 30 min. The ultrasonically cleaned polyurethane sponge was then etched using a 5 wt.% sodium hydroxide solution at 60°C for 45 min. Afterward, it was washed and dried with water until the pH of the filtrate reached 7. The drying temperature was 60°C, and the drying time was 2 h to obtain the pretreated template. Step 2, Preparation of Composite Slurry: This includes GO-carbon fiber pre-dispersion, matrix mixing, and introduction of functional components to prepare the composite slurry, specifically as follows: Step 2-1, GO-carbon fiber pre-dispersion: A 1 wt.% graphene oxide (GO) dispersion was mixed with short-cut carbon fibers at a mass ratio of 1.7:1. The mixture was then magnetically stirred at 400 rpm for 10 min and ultrasonically treated at 250 W for 20 min to obtain a uniform and stable pre-dispersion. The graphene oxide (GO) sheet has a diameter range of 8-15 μm, wherein the proportion of monolayer graphene oxide is not less than 90%, and its thickness ranges from 0.9-1.1 nm. The chopped carbon fibers have a single filament diameter ranging from 7-10 μm, a length ranging from 1-3 mm, a tensile modulus ≥200 GPa, a tensile strength ≥3000 MPa, and a carbon content ≥96%. Step 2-2, Matrix Mixing: Add a 35 wt.% polyamic acid (PAAc) solution and a 30 wt.% waterborne polyurethane (WPU) solution to the pre-dispersion solution from Step 2-1, wherein the mass ratio of the pre-dispersion solution, polyamic acid (PAAc) solution, and waterborne polyurethane (WPU) solution is 0.2:1:1.1. After stirring in a 50°C water bath at 300 rpm for 1 hour, a matrix mixture is obtained. The polyamic acid (PAAc) solution is composed of deionized water (30%) and co-solvent N-methylpyrrolidone (NMP, 70%), and has a viscosity of 1500 mPa·s at 25°C; wherein the polyamic acid (PAAc) has a molecular weight of 200,000 g / mol and a carboxyl content of 4.8 mmol / g. The solvent of the aqueous polyurethane (WPU) solution is composed of deionized water (90%) and co-solvent N-methylpyrrolidone (NMP, 10%), and has a viscosity of 300 mPa·s at 25°C; wherein the hydroxyl value of the aqueous polyurethane (WPU) is 50 mgKOH / g. Steps 2-3, introduction of functional components, specifically: 1) Aqueous epoxy resin and triethylenetetramine (TETA) were premixed at a mass ratio of 10:1 and activated by magnetic stirring at 300 rpm for 8 min to obtain an activated epoxy resin-TETA mixture; wherein the epoxy equivalent (EEW) of the aqueous epoxy resin was 480 g / eq. The aqueous epoxy resin was used in the form of an aqueous dispersion with a solid content of 45 wt.% and a viscosity of 800 mPa·s at 25°C; the triethylenetetramine (TETA) had a molecular weight of 146.23 g / mol, an amine hydrogen equivalent of 36.5 g / eq, a purity ≥98 wt.%, and an impurity content <0.1 wt.%. 2) Add the following to the matrix mixture in sequence: activated epoxy resin-TETA mixture, ammonium bicarbonate, and carbon aerogel powder, wherein the mass ratio of matrix mixture: activated epoxy resin-TETA mixture: ammonium bicarbonate: carbon aerogel powder is 12:8:2:1. The ammonium bicarbonate has a molecular weight of 79.06 g / mol and a purity of ≥99 wt.%. The carbon aerogel has a particle size range of 8-12 μm, a density of 0.17 g / cm³, a porosity of ≥90%, and a specific surface area of ​​≥600 m². 2 / g, with ≥90% having a pore size range of 20-50nm; 3) Stir at 200 rpm for 30 minutes to ensure uniform dispersion; 4) The viscosity of the slurry was controlled at 4800 mPa•s by adding 0.5 wt.% of deionized water in batches, stirring magnetically at 300 rpm for 5 minutes, and measuring the viscosity with a rotational viscometer after mixing evenly. Step 3, Template Impregnation and Curing: including vacuum impregnation and step-by-step curing; Step 3-1, Vacuum Impregnation: Immerse the pre-treated template in the slurry, ensuring that the slurry surface completely covers the sponge and is 1.5cm above its top surface. Then place the entire impregnation system in a vacuum environment, evacuate to -0.09MPa and maintain for 40min. Step 3-2, Step-by-step curing: 1) Dry at 60℃ with forced air for 5 hours: 2) Heat to 120℃ and cure for 3 hours to obtain a cured preform; Step 4: Template removal and pre-oxidation, i.e., thermal decomposition; The cured preform was placed in a muffle furnace and subjected to programmed temperature rise heat treatment in an air atmosphere: the temperature was raised from room temperature to 200°C at a rate of 10°C / min and held at 200°C for 3 hours; then the temperature was raised to 300°C at a rate of 10°C / min and held at 300°C for 3 hours to obtain a composite preform, which was then removed after cooling to room temperature. Step 5: After high-temperature treatment of the composite preform, a carbon-carbon composite high heat-resistant foam material is obtained. Specifically, the composite preform is placed in a tube furnace, nitrogen gas is introduced at a flow rate of 50 mL / min, and the temperature is raised from room temperature to 600℃ and held for 2 hours in a nitrogen atmosphere. Then, it is heated to 1300℃ and held for 2 hours. Finally, it is naturally cooled to room temperature to obtain a carbon-carbon composite high heat-resistant foamed material.

[0062] The density of the carbon-carbon composite high thermal resistance foam material is 0.19 g / cm³. 3 It has a compressive strength of 0.55 MPa and a thermal conductivity of 0.42 W / (m·K) at 1000℃.

[0063] Example 4 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material. The difference from Example 1 is that the mass ratio of graphene oxide (GO) dispersion to chopped carbon fibers is 2:1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0064] The density of the carbon-carbon composite high thermal resistance foam material is 0.17 g / cm³. 3 It has a compressive strength of 0.61 MPa and a thermal conductivity of 0.46 W / (m·K) at 1000℃.

[0065] Example 5 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material. The difference from Example 1 is that the mass ratio of graphene oxide (GO) dispersion to chopped carbon fibers is 1.5:1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0066] The density of the carbon-carbon composite high thermal resistance foam material is 0.20 g / cm³. 3 It has a compressive strength of 0.53 MPa and a thermal conductivity of 0.44 W / (m·K) at 1000℃.

[0067] Example 6 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material. The difference from Example 1 is that the mass ratio of activated epoxy resin-TETA mixture: ammonium bicarbonate: carbon aerogel powder is 12:8:1:1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0068] The density of the carbon-carbon composite high thermal resistance foam material is 0.16 g / cm³. 3 It has a compressive strength of 0.49 MPa and a thermal conductivity of 0.38 W / (m·K) at 1000℃.

[0069] Example 7 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material. The difference from Embodiment 1 is that the cured preform is subjected to programmed temperature rise heat treatment in an air atmosphere: the temperature is raised from room temperature to 200°C at a heating rate of 10°C / min, and held at 200°C for 2 hours; then, the temperature is raised to 300°C at a heating rate of 10°C / min, and held at 300°C for 2 hours. The remaining raw materials and preparation conditions are exactly the same as in Embodiment 1.

[0070] The density of the carbon-carbon composite high thermal resistance foam material is 0.21 g / cm³. 3 It has a compressive strength of 0.54 MPa and a thermal conductivity of 0.47 W / (m·K) at 1000℃.

[0071] Example 8 This embodiment provides a method for preparing a carbon-carbon composite high thermal resistance foam material. The difference from Embodiment 1 is that the composite preform is placed in a tube furnace, nitrogen gas is introduced at a flow rate of 50 mL / min, and the temperature is raised from 300°C to 600°C and held for 2 hours in a nitrogen atmosphere. Then, it is heated to 1300°C and held for 3 hours. The remaining raw materials and preparation conditions are exactly the same as in Embodiment 1.

[0072] The density of the carbon-carbon composite high thermal resistance foam material is 0.22 g / cm³. 3 It has a compressive strength of 0.63 MPa and a thermal conductivity of 0.53 W / (m·K) at 1000℃.

[0073] Comparative Example 1 This comparative example provides a foaming material that, compared to Example 1, does not use sodium hydroxide solution to pretreat the polyurethane foam, while the remaining raw materials and preparation conditions are exactly the same as in Example 1.

[0074] The density of the foamed material is uneven, ranging from 0.18 to 0.32 g / cm³. 3 Between these values, the compressive strength is 0.31 MPa, and the thermal conductivity at 1000℃ is 1.85 W / (m·K).

[0075] The core function of alkaline etching in this invention is to "hydrolyze the ester bonds of the sponge to generate amino / carboxyl hydrophilic groups, thereby improving the wettability of the slurry"; while without etching, the polyurethane sponge surface is highly hydrophobic, and the slurry cannot fully penetrate the pores, resulting in: 1. Numerous unfilled voids and defects (uneven density) are formed inside the billet. 2. Voids disrupt the three-dimensional cross-linked network, making it prone to collapse under stress (rapid drop in compressive strength). 3. Increased air convection within the cavity (significantly increased thermal conductivity).

[0076] Comparative Example 2 This comparative example provides a foaming material that, compared to Example 1, uses a large-pore polyurethane sponge with an inner diameter of 800-1000 μm. The other raw materials and preparation conditions are exactly the same as in Example 1.

[0077] The density of the foamed material is 0.14 g / cm³. 3 It has a compressive strength of 0.08 MPa and a thermal conductivity of 2.02 W / (m·K) at 1000℃.

[0078] The material has a sparse skeleton and extremely low strength. The excessively large pore size results in a carbon ligament with an excessively high aspect ratio and a sparse structure, making it extremely prone to instability and fracture under pressure. Although the material has a very low density, its strength is completely inadequate, and the large-pore structure provides weak protection against radiative heat transfer, leading to high thermal conductivity at high temperatures.

[0079] Comparative Example 3 This comparative example provides a foaming material in which the sodium hydroxide solution is replaced with a sodium carbonate solution at a concentration of 5 wt.% compared to Example 1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0080] The density of the foamed material is 0.15 g / cm³. 3 It has a compressive strength of 0.22 MPa and a thermal conductivity of 0.98 W / (m·K) at 1000℃.

[0081] In this invention, the core function of sodium hydroxide is "strong alkaline and efficient hydrolysis of sponge ester bonds"; sodium carbonate is weakly alkaline, and its hydrolysis efficiency is only 30%-40% of that of sodium hydroxide, resulting in an insufficient number of hydrophilic groups generated, leading to: 1. Insufficient wettability of the slurry, low cross-linking density of the green body, and low compressive strength; 2. Insufficient wetting in certain areas creates tiny pores, which enhances air convection and increases thermal conductivity; 3. Insufficient wetting leads to unfilled voids.

[0082] Comparative Example 4 This comparative example provides a foaming material that, compared to Example 1, uses only short-cut carbon fibers and does not use graphene oxide (GO) dispersion for modification, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0083] The density of the foamed material is 0.25 g / cm³. 3 It has a compressive strength of 0.37 MPa and a thermal conductivity of 0.82 W / (m·K) at 1000℃.

[0084] In this invention, the core function of graphene oxide (GO) is to "adsorb onto the surface of carbon fibers and fill micropores," and to form a dense interface by fixing it with an adhesive. Without graphene oxide (GO), the carbon fiber surface has low activity, the interface with the matrix (PAAc / WPU) is loose, and it is easy to break under stress. During heat treatment, the fiber and the matrix are easy to separate, and the stress cannot be effectively transferred (compressive strength drops sharply). The increased interfacial gaps lead to an increase in heat conduction paths (increased thermal conductivity). At the same time, the loose structure requires more slurry to fill (increased density).

[0085] Comparative Example 5 This comparative example provides a foaming material that, compared to Example 1, does not contain waterborne polyurethane (WPU), while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0086] The density of the foamed material is 0.18 g / cm³. 3 It has a compressive strength of 0.32 MPa and a thermal conductivity of 0.75 W / (m·K) at 1000℃.

[0087] The core function of WPU in this invention is to "form hydrogen bond crosslinking with PAAc carboxyl groups (improving toughness) + fill PI defects with residual carbon after carbonization"; without WPU, the matrix is ​​only crosslinked with PAAc, resulting in poor toughness, incomplete skeleton after carbonization, and easy brittle fracture under stress (sudden drop in compressive strength); without the residual carbon of WPU filling the defects in the PI carbon skeleton, micropores are formed (increased thermal conductivity).

[0088] Comparative Example 6 This comparative example provides a material that, compared to Example 1, does not contain waterborne epoxy resin and triethylenetetramine (TETA), while the remaining raw materials and preparation conditions are exactly the same as in Example 1.

[0089] The material collapsed during the template removal process, failing to form a complete foam.

[0090] The core function of waterborne epoxy resin and TETA in this invention is to form a three-dimensional cross-linked network through ring-opening polymerization, thereby improving the strength of the preform. The three-dimensional cross-linked network formed by epoxy and TETA is the key to giving the composite preform sufficient strength to support subsequent heat treatment without collapse. Without this network, the preform strength is extremely low, and the structure collapses. Without this system, the preform strength is insufficient, and the structure is extremely prone to collapse during template removal and carbonization, making it impossible to form a complete foam.

[0091] Comparative Example 7 This comparative example provides a foaming material that, compared to Example 1, does not contain ammonium bicarbonate, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0092] The density of the foamed material is 0.48 g / cm³. 3 It has a compressive strength of 1.72 MPa and a thermal conductivity of 2.25 W / (m·K) at 1000℃.

[0093] In this invention, the ammonium bicarbonate foaming agent decomposes and creates pores during the pre-oxidation stage, which is crucial for obtaining a low-density structure. Excessive density leads to increased strength, but poor thermal insulation. Without sufficient foaming agent, the material cannot form enough micropores, resulting in high density. While the strength is acceptable, the thermal conductivity is high, making it unsuitable for efficient thermal insulation.

[0094] Comparative Example 8 This comparative example provides a foaming material in which ammonium bicarbonate is replaced with azodicarbonamide (ADC) in contrast to Example 1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0095] The density of the foamed material is 0.25 g / cm³. 3 It has a compressive strength of 0.35 MPa and a thermal conductivity of 0.98 W / (m·K) at 1000℃.

[0096] The core advantage of ammonium bicarbonate in this invention is its "decomposition temperature matched to pre-oxidation (initial decomposition at 60-100℃, violent decomposition at 200℃)," which allows for uniform pore formation. The ADC decomposition temperature (200-220℃) is higher than the pre-oxidation temperature, resulting in: 1. Delayed foaming causes pores to form after curing, disrupting the cross-linked structure (leading to a sharp drop in compressive strength). 2. Uneven pore size (partial pore collapse), requiring more slurry to fill (increased density); 3. Uneven channels cannot effectively block heat conduction (increase thermal conductivity).

[0097] Comparative Example 9 This comparative example provides a foaming material that, compared to Example 1, does not contain carbon aerogel, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0098] The density of the foamed material is 0.22 g / cm³. 3 It has a compressive strength of 0.45 MPa and a thermal conductivity of 1.21 W / (m·K) at 1000℃.

[0099] The core function of carbon aerogel in this invention is to "construct a pre-fabricated porous carbon network to block heat conduction and provide structural support." Carbon aerogel is added as a filler; its density is extremely low. When this lightweight component is absent, the density of the composite material increases. Simultaneously, the thermal conductivity of the composite material increases due to the lack of the nanoporous thermal insulation network provided by the carbon aerogel. Furthermore, the strength of the composite material slightly decreases due to the absence of the supporting effect provided by the carbon aerogel.

[0100] Comparative Example 10 This comparative example provides a foaming material in which, compared to Example 1, the slurry viscosity is controlled to 8000 mPa•s in steps 2-3, and the remaining raw materials and preparation conditions are exactly the same as in Example 1.

[0101] The density of the foamed material is 0.15 g / cm³. 3 It has a compressive strength of 0.28 MPa and a thermal conductivity of 0.76 W / (m·K) at 1000℃.

[0102] The viscosity of the slurry in this invention is controlled at 3000-5000 mPa. s is the optimal viscosity to ensure the slurry penetrates deep into the sponge; 8000 mPa At time s, the slurry has poor fluidity and can only penetrate 10%-20% of the sponge surface, resulting in: 1. There are many unfilled areas inside (reduced density); 2. The surface and internal structure are uneven, making it prone to delamination under stress (compressive strength is below the lower limit). 3. Internal cavities enhance heat conduction (increase thermal conductivity).

[0103] Comparative Example 11 This comparative example provides a foaming material, which, compared to Example 1, uses atmospheric pressure impregnation instead of vacuum impregnation, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0104] The density of the foamed material is 0.29 g / cm³. 3It has a compressive strength of 0.46 MPa and a thermal conductivity of 2.43 W / (m·K) at 1000℃.

[0105] The impregnation in this comparative example was incomplete, resulting in an uneven structure. Air trapped in the template pores could not be eliminated; the slurry could only fill the surface and large pores, creating numerous voids inside. This resulted in a product with high density but low structural strength, and the presence of heat flow short-circuit paths, leading to extremely poor thermal insulation performance.

[0106] Comparative Example 12 This comparative example provides a material that, compared to Example 1, uses a one-step curing method instead of step-by-step curing, and is cured at 120°C for 8 hours. The remaining raw materials and preparation conditions are exactly the same as in Example 1.

[0107] The material cracks during the curing process, making it impossible to form a complete foam.

[0108] The comparative example billet cracked, resulting in structural damage. The lack of a gentle drying stage at 60°C led to rapid moisture evaporation, causing cracks and defects in the pore walls. These defects will expand during subsequent heat treatment, severely impairing the mechanical strength and structural integrity of the final material.

[0109] Comparative Example 13 This comparative example provides a material that, compared to Example 1, is not pre-oxidized, i.e., not pre-oxidized in an air atmosphere at 200-300°C, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0110] The material blank expands and cracks during heat treatment, making it impossible to form a complete foam.

[0111] The core function of the pre-oxidation process in this invention is to "remove the polyurethane template and initially stabilize the carbon skeleton." The pre-oxidation process simultaneously and slowly achieves the thermal decomposition and removal of the polymer template and the decomposition and pore-forming of the foaming agent. Without the pre-oxidation step, the template and foaming agent decompose rapidly during high-temperature carbonization, generating a large amount of gas, leading to the destruction of the preform and making it impossible to obtain the target product.

[0112] Comparative Example 14 This comparative example provides a foaming material, in which the heat treatment temperature is adjusted from 1300°C to 800°C compared to Example 1, while the other raw materials and preparation conditions are exactly the same as in Example 1.

[0113] The density of the foamed material is 0.23 g / cm³. 3 It has a compressive strength of 0.33 MPa and a thermal conductivity of 0.92 W / (m·K) at 1000℃.

[0114] The core function of 1300℃ in this invention is to "promote the decomposition of the PI main chain (removal of O / N / H heteroatoms) + the growth of graphite microcrystals"; insufficient heating at 800℃ results in a heteroatom residue of 15%-20%, leading to: 1. Residual impurities increase material density; 2. Incomplete growth of graphite microcrystals results in low strength of the carbon skeleton; 3. Heteroatoms act as heat carriers, leading to increased thermal conductivity.

[0115] It should be understood that the present invention is not limited to the content already described above, and various modifications and changes can be made without departing from its scope. The scope of the present invention is limited only by the appended claims.

Claims

1. A carbon-carbon composite high thermal resistance foam material, characterized in that, The foaming material is obtained from a composite preform through heat treatment; The composite preform is prepared by impregnating an alkali-etched polyurethane sponge as a template, using polyamic acid and waterborne epoxy resin as carbon skeletons, waterborne polyurethane as a filler skeleton, ammonium bicarbonate as a foaming agent, graphene oxide-modified carbon fiber as a reinforcing phase, and carbon aerogel as a heat-insulating reinforcing phase, and then curing it.

2. The carbon-carbon composite high thermal resistance foam material according to claim 1, characterized in that, The density of the carbon-carbon composite high thermal resistance foam material is 0.16-0.22 g / cm³. 3 Its compressive strength is 0.49-0.63 MPa, and its thermal conductivity at 1000℃ is 0.38-0.53 W / (m·K).

3. A method for preparing a carbon-carbon composite high thermal resistance foamed material according to any one of claims 1-2, characterized in that, This includes template pretreatment, composite slurry preparation, template impregnation and curing, and heat treatment.

4. The method for preparing the carbon-carbon composite high thermal resistance foamed material according to claim 3, characterized in that, The preparation method includes the following specific steps: Step 1, Template Pretreatment: Use an alkaline solution to etch the polyurethane foam to obtain a pretreated template; Step 2, Preparation of composite slurry: This includes pre-dispersion of graphene oxide-carbon fiber, matrix mixing, and introduction of functional components to prepare the composite slurry; Step 3: Template impregnation and curing; Step 4: Template removal and pre-oxidation, i.e., thermal decomposition; Step 5: After high-temperature treatment of the composite preform, a carbon-carbon composite high heat-resistant foam material is obtained.

5. The method for preparing the carbon-carbon composite high thermal resistance foamed material according to claim 4, characterized in that, Step 2 is as follows: Step 2-1, Graphene oxide-carbon fiber pre-dispersion: The graphene oxide dispersion is mixed with carbon fiber, and after mechanical stirring and ultrasonic treatment, a uniform and stable pre-dispersion is obtained. Step 2-2, Matrix Mixing: Add polyamic acid solution and aqueous polyurethane solution to the pre-dispersion solution in Step 2-1, and stir to obtain matrix mixture; Steps 2-3: Introduction of functional components.

6. The method for preparing the carbon-carbon composite high thermal resistance foamed material according to claim 4, characterized in that, Step 3 specifically involves: Step 3-1: Vacuum impregnation; Step 3-2: Step-by-step curing.

7. The method for preparing the carbon-carbon composite high thermal resistance foamed material according to claim 4, characterized in that, Step 5 specifically involves placing the composite preform in a tube furnace, introducing nitrogen gas, heating it from room temperature to 600°C in a nitrogen atmosphere, then heating it to 1300°C, and finally naturally cooling it to room temperature to obtain a carbon-carbon composite high heat-resistant foamed material.

8. A thermal insulation component, characterized in that, The thermal insulation component includes the high thermal resistance foamed material of carbon-carbon composite as described in any one of claims 1-2.

9. A high-temperature treatment furnace, characterized in that, The high-temperature treatment furnace includes the heat-insulating component as described in claim 8.

10. The high-temperature treatment furnace according to claim 9, characterized in that, The high-temperature processing furnace is selected from any one of a single-crystal silicon furnace, sintering furnace, ingot casting furnace, or chemical vapor deposition furnace.