Preparation process of high-strength carbon fiber felt

Abstract

The invention discloses a preparation process of a high-strength carbon fiber felt, which comprises the following steps: (1) dipping a carbon fiber felt in a non-aqueous solvent containing gamma-(2, 3-epoxypropoxy) propyltrimethoxysilane or gamma-methacryloyloxy propyltrimethoxysilane to obtain a pretreated carbon fiber felt; and (2) adding tetraethoxysilane into an ethanol water solution, uniformly mixing, then adding the pretreated carbon fiber felt, and carrying out hydrolytic condensation reaction under a heating condition to obtain the modified carbon fiber felt after the hydrolytic condensation reaction is completed. And (3) infiltrating the modified carbon fiber felt in a thermosetting resin liquid, carrying out hot-pressing curing molding treatment on the modified carbon fiber felt infiltrated with the resin, and then carrying out carbonization and graphitization treatment in a nitrogen-containing protective atmosphere to obtain the carbon fiber hard felt after the carbonization and graphitization treatment is completed. The process provided by the invention not only can improve the binding force between the resin material and the carbon fibers, but also can avoid the damage of surface activation to the carbon fibers, and improves the strength of the carbon fiber felt.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber felt preparation, and in particular to a preparation process of high-strength carbon fiber felt. Background Art

[0002] Carbon fiber felt is a lightweight, high-strength material made from carbon fiber as the main material, which is then compounded with a resin material and then processed through processes such as carbonization and graphitization. It has excellent corrosion resistance, electrical conductivity, thermal insulation and high-temperature resistance, and is widely used in aerospace, sports equipment, medical machinery, automobile manufacturing and other fields. In addition, carbon fiber felt is also used as a thermal insulation material in vacuum furnaces, single crystal furnaces, induction furnaces, carbonization furnaces, high-frequency furnaces, etc., which helps to reduce energy consumption and reduce production costs. Due to the low surface energy of carbon fiber, its ability to bind to resin materials is insufficient. Before compounding carbon fiber with resin-based materials, it is usually necessary to perform surface activation treatment on the carbon fiber. A commonly used method is to use strong oxidizing acids such as nitric acid and sulfuric acid to oxidize the carbon fiber surface to increase the roughness of the fiber surface. However, this activation method comes at the cost of destroying and damaging the carbon fiber surface, which will cause the strength of the carbon fiber to decrease, and thus lead to a decrease in the strength of the prepared carbon fiber felt. Summary of the Invention

[0003] To address the above issues, the present invention provides a process for preparing high-strength carbon fiber felt, which not only improves the bonding strength between the resin material and the carbon fibers, but also avoids damage to the carbon fibers during surface activation, thereby avoiding the adverse effects on the strength of the carbon fiber felt. Specifically, the technical solution of the present invention is as follows.

[0004] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) The carbon fiber felt is immersed in a non-aqueous solvent containing γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane to obtain a pretreated carbon fiber felt.

[0005] (2) adding ethyl orthosilicate to an ethanol aqueous solution and mixing the mixture evenly; then adding the pretreated carbon fiber felt; and performing a hydrolysis condensation reaction under heating conditions to obtain a modified carbon fiber felt.

[0006] (3) The modified carbon fiber felt is immersed in a thermosetting resin liquid, and then the modified carbon fiber felt immersed in the resin is subjected to a hot pressing curing molding process. The obtained composite carbon fiber felt is carbonized and graphitized in a protective atmosphere containing nitrogen to obtain the carbon fiber hard felt.

[0007] Furthermore, in step (1), the mass fraction of γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane in the non-aqueous solvent is 0.7-1.5%.

[0008] Furthermore, in step (1), the non-aqueous solvent includes at least one of anhydrous methanol, anhydrous ethanol, etc. Optionally, in step (1), the immersion time is 45 to 60 minutes.

[0009] Furthermore, in step (2), the mass fraction of ethyl orthosilicate in the ethanol aqueous solution is 1-2%. Alternatively, the mass fraction of the ethanol aqueous solution is 75-90%.

[0010] Furthermore, in step (2), the heating temperature is 150-170° C., and the reaction time is 1-1.5 hours.

[0011] Furthermore, in step (3), the resin solution comprises at least one of epoxy resin diluent, phenolic resin diluent, furan resin diluent, vinyl ester diluent, etc. Optionally, the mass fraction of the resin solution is 15-20%. Optionally, in step (3), the impregnation time is 2-4 hours.

[0012] Furthermore, in step (3), the temperature of the hot pressing curing is 180-250° C., and the time is 4-7 hours.

[0013] Furthermore, in step (3), the protective atmosphere is argon containing nitrogen. Preferably, the volume proportion of nitrogen in the protective atmosphere is 15-20%.

[0014] Furthermore, in step (3), the temperature of the carbonization treatment is 900-1100° C., and the time is 1.5-3 h.

[0015] Furthermore, in step (3), the graphitization treatment is performed at a temperature of 2300-2500° C. for a time of 2.5-5 h.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: (1) The present invention effectively avoids the problem of damage to the carbon fiber surface caused by the traditional activation treatment of the carbon fiber surface with strong oxidizing acid, which leads to a decrease in the mechanical properties of the carbon fiber felt. This is because: the present invention first uses the organic functional groups on the carbon fiber surface to graft γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane, and then further treats it with an ethanol aqueous solution containing ethyl orthosilicate. In this process, the ethyl orthosilicate is hydrolyzed under the action of water in the ethanol aqueous solution to form a silanol group (-Si(OH)3), which further undergoes a dehydration condensation reaction with the silanol group (-Si-OH) on the γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane on the carbon fiber surface, thereby connecting the silanol group to the carbon fiber surface to form a silicon-rich product. When the modified carbon fiber felt obtained through the above process is compounded with the resin liquid, the organic matter loaded on the carbon fiber surface can effectively improve the compatibility between the fiber surface and the resin liquid, and improve the bonding ability between the two, while not causing damage to the fiber surface, thereby avoiding the deterioration of the strength of the carbon fiber.

[0017] (2) When the carbon fiber felt treated as above is further carbonized in a protective atmosphere containing nitrogen, the silicon-rich product on the surface of the carbon fiber reacts with carbon atoms to form silicon carbide, which helps to improve the mechanical strength and fracture toughness of the carbon fiber felt. At the same time, part of the silicon-rich product reacts with active nitrogen atoms formed by nitrogen in the protective atmosphere at high temperature to form silicon nitride. In the further graphitization process, the silicon nitride melts and not only anchors the silicon carbide on the carbon fiber, but also acts as a bond to the carbon fiber bundle, further improving the mechanical strength and fracture toughness of the carbon fiber felt. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0019] Figure 1 This is a sample picture of high-strength carbon fiber hard felt prepared in Example 1 below. DETAILED DESCRIPTION

[0020] The present invention will be further described below with reference to specific examples. It should be understood that these examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. In addition, any methods and materials similar or equivalent to those described herein may be applied to the method of the present invention. The preferred embodiments and materials described herein are for exemplary purposes only. The technical solutions of the present invention will now be described in further detail with reference to the accompanying drawings and specific examples. Example 1

[0021] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane to anhydrous ethanol and stir evenly to obtain a pretreatment solution with a mass fraction of 1.2%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:30ml) and immerse for 60 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0022] (2) Add tetraethyl orthosilicate to an 85% by mass ethanol aqueous solution and stir evenly to form a modified solution with a 1.5% by mass fraction of tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modified solution (the ratio of the two is 1 g:30 ml). After sealing the reaction vessel, heat it to 170°C for 1 hour to carry out a hydrolysis-condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0023] (3) The epoxy resin is diluted with ethanol to form an epoxy resin dilution solution with a mass fraction of 20%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 2 hours. After completion, the modified carbon fiber felt immersed in the resin is subjected to a hot press curing molding process at 220°C for 5 hours. The obtained composite carbon fiber felt is then carbonized (temperature 1020°C, time 2.5h) in a protective atmosphere (argon: nitrogen (v / v) = 80%: 20%), and then heated to 2450°C for graphitization treatment for 4 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt, and its sample is as shown below. Figure 1 shown.

[0024] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 297.24 MPa, flexural strength = 1.68 MPa. Example 2

[0025] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-methacryloxypropyltrimethoxysilane to anhydrous methanol and stir evenly to obtain a pretreatment solution with a mass fraction of 0.7%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:30ml) and immerse for 50 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0026] (2) Add tetraethyl orthosilicate to a 90% by mass ethanol aqueous solution and stir evenly to form a modified solution with a 2% by mass fraction of tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modified solution (the ratio of the two is 1 g:30 ml). After sealing the reaction vessel, heat it to 150°C for 1 hour to carry out a hydrolysis and condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0027] (3) The phenolic resin is diluted with ethanol to form a phenolic resin dilution solution with a mass fraction of 18%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 3 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 250°C for 4 hours. The obtained composite carbon fiber felt is then carbonized (temperature 900°C, time 3h) in a protective atmosphere (argon: nitrogen (v / v) = 85%: 15%), and then heated to 2500°C for graphitization treatment for 2.5 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0028] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 290.13 MPa, flexural strength = 1.64 MPa. Example 3

[0029] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-methacryloxypropyltrimethoxysilane to anhydrous ethanol and stir evenly to obtain a pretreatment solution with a mass fraction of 1.5%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:20ml) and soak for 45 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0030] (2) Add tetraethyl orthosilicate to a 75% by mass ethanol aqueous solution and stir evenly to form a modified solution with a 1% by mass fraction of tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modified solution (the ratio of the two is 1 g:20 ml). After sealing the reaction vessel, heat it to 160°C for 1.5 hours to carry out a hydrolysis and condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0031] (3) The epoxy resin is diluted with toluene to form an epoxy resin dilution solution with a mass fraction of 15%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 4 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 180°C for 7 hours. The obtained composite carbon fiber felt is then carbonized (temperature 1100°C, time 1.5h) in a protective atmosphere (argon: nitrogen (v / v) = 80%: 20%), and then heated to 2300°C for graphitization treatment for 5 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0032] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 282.57 MPa, and flexural strength = 1.57 MPa. Example 4

[0033] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add PAN-based carbon fiber felt to anhydrous ethanol (the ratio of the two is 1g:30ml) and soak for 60 minutes. After completion, take out the pretreated carbon fiber felt and set aside.

[0034] (2) Add tetraethyl orthosilicate to an 85% by mass ethanol aqueous solution and stir evenly to form a modified solution with a 1.5% by mass fraction of tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modified solution (the ratio of the two is 1 g:30 ml). After sealing the reaction vessel, heat it to 170°C for 1 hour to carry out a hydrolysis-condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0035] (3) The epoxy resin is diluted with ethanol to form an epoxy resin dilution solution with a mass fraction of 20%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 2 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 220°C for 5 hours. The obtained composite carbon fiber felt is then carbonized (temperature 1020°C, time 2.5h) in a protective atmosphere (argon: nitrogen (v / v) = 80%: 20%), and then heated to 2450°C for graphitization treatment for 4 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0036] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 268.44 MPa, flexural strength = 1.28 MPa. Example 5

[0037] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-methacryloxypropyltrimethoxysilane to anhydrous ethanol and stir evenly to obtain a pretreatment solution with a mass fraction of 1.5%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:20ml) and soak for 45 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0038] (2) Immerse the pretreated carbon fiber felt in 75% ethanol aqueous solution (the ratio of the two is 1 g:20 ml), seal the reaction container and heat it to 160°C for 1.5 hours to carry out hydrolysis condensation reaction. After completion, take out the modified carbon fiber felt and set aside.

[0039] (3) The epoxy resin is diluted with toluene to form an epoxy resin dilution solution with a mass fraction of 15%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 4 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 180°C for 7 hours. The obtained composite carbon fiber felt is then carbonized (temperature 1100°C, time 1.5h) in a protective atmosphere (argon: nitrogen (v / v) = 80%: 20%), and then heated to 2300°C for graphitization treatment for 5 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0040] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 251.83 MPa, flexural strength = 1.12 MPa. Example 6

[0041] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-methacryloxypropyltrimethoxysilane to anhydrous methanol and stir evenly to obtain a pretreatment solution with a mass fraction of 0.7%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:30ml) and immerse for 50 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0042] (2) Add tetraethyl orthosilicate to a 90% by mass ethanol aqueous solution and stir evenly to form a modified solution with a 2% by mass fraction of tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modified solution (the ratio of the two is 1 g:30 ml). After sealing the reaction vessel, heat it to 150°C for 1 hour to carry out a hydrolysis and condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0043] (3) The phenolic resin is diluted with ethanol to form a phenolic resin dilution solution with a mass fraction of 18%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 3 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 250°C for 4 hours. The obtained composite carbon fiber felt is then carbonized in a nitrogen protective atmosphere (temperature 900°C, time 3h), and then heated to 2500°C for graphitization treatment for 2.5 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0044] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 271.16 MPa, and flexural strength = 1.41 MPa. Example 7

[0045] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add γ-(2,3-epoxypropoxy)propyltrimethoxysilane to anhydrous ethanol and stir evenly to obtain a pretreatment solution with a mass fraction of 1.2%. Then add PAN-based carbon fiber felt to the pretreatment solution (the ratio of the two is 1g:30ml) and immerse for 60 minutes. After completion, remove the pretreated carbon fiber felt and set aside.

[0046] (2) Add tetraethyl orthosilicate to anhydrous ethanol and stir evenly to form a modification solution with a mass fraction of 1.5% tetraethyl orthosilicate. Then, immerse the pretreated carbon fiber felt in the modification solution (the ratio of the two is 1 g:30 ml). After sealing the reaction vessel, heat it to 170°C for 1 hour to carry out a hydrolysis and condensation reaction. After completion, remove the modified carbon fiber felt and set aside.

[0047] (3) The epoxy resin is diluted with ethanol to form an epoxy resin dilution solution with a mass fraction of 20%, and the modified carbon fiber felt is placed in the dilution solution and immersed for 2 hours. After completion, the modified carbon fiber felt immersed in the resin is hot-pressed and cured at 220°C for 5 hours. The obtained composite carbon fiber felt is then carbonized (temperature 1020°C, time 2.5h) in a protective atmosphere (argon: nitrogen (v / v) = 80%: 20%), and then heated to 2450°C for graphitization treatment for 4 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0048] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Carbon Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 267.03 MPa, flexural strength = 1.33 MPa. Example 8

[0049] A preparation process of high-strength carbon fiber felt comprises the following steps: (1) Add PAN-based carbon fiber felt to concentrated sulfuric acid (the ratio of the two is 1g:30ml) and immerse for 50 minutes. After completion, take out the pretreated carbon fiber felt and set aside.

[0050] (2) The phenolic resin is diluted with ethanol to form a phenolic resin dilution solution with a mass fraction of 18%, and the pretreated carbon fiber felt is placed in the dilution solution and immersed for 3 hours. After completion, the modified carbon fiber felt impregnated with the resin is hot-pressed and cured at 250°C for 4 hours. The obtained composite carbon fiber felt is then carbonized (temperature 900°C, time 3h) in a protective atmosphere (argon: nitrogen (v / v) = 85%: 15%), and then heated to 2500°C for graphitization treatment for 2.5 hours. After completion, it is cooled to room temperature to obtain a carbon fiber hard felt.

[0051] The longitudinal tensile strength of the carbon fiber rigid felt prepared in this example was tested according to the "Test Method for Tensile Properties of Fiber-Reinforced Plastics" (GBT 1447-2005). The flexural strength of the carbon fiber rigid felt was tested according to the "Test Methods for Carbon-Carbon Composite Carbon Materials" (GB / T 40398.2-2021), Part 2, "Flexural Properties Test." The results were: longitudinal tensile strength = 232.82 MPa, and flexural strength = 0.93 MPa.

[0052] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A process for preparing high-strength carbon fiber felt, characterized in that: The steps include: (1) impregnating the carbon fiber felt in a non-aqueous solvent containing γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane to obtain a pretreated carbon fiber felt; (2) adding ethyl orthosilicate to an ethanol aqueous solution and mixing the mixture evenly, then adding the pretreated carbon fiber felt, and performing a hydrolysis condensation reaction under heating conditions to obtain a modified carbon fiber felt; (3) The modified carbon fiber felt is immersed in a thermosetting resin liquid, and then the modified carbon fiber felt immersed in the resin is subjected to a hot pressing curing molding process; the obtained composite carbon fiber felt is carbonized and graphitized in a protective atmosphere containing nitrogen, and the carbon fiber hard felt is obtained after completion.

2. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (1), the mass fraction of γ-(2,3-epoxypropoxy)propyltrimethoxysilane or γ-methacryloxypropyltrimethoxysilane in the non-aqueous solvent is 0.7-1.5%.

3. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (1), the non-aqueous solvent includes at least one of anhydrous methanol and anhydrous ethanol; Optionally, in step (1), the immersion time is 45 to 60 minutes.

4. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (2), the mass fraction of ethyl orthosilicate in the ethanol aqueous solution is 1-2%; Optionally, in step (2), the mass fraction of the ethanol aqueous solution is 75-90%.

5. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (2), the heating temperature is 150-170° C., and the reaction time is 1-1.5 hours.

6. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (3), the resin liquid includes at least one of epoxy resin diluent, phenolic resin diluent, furan resin diluent, and vinyl ester diluent; Optionally, in step (3), the mass fraction of the resin liquid is 15-20%; Optionally, in step (3), the infiltration time is 2 to 4 hours.

7. The process for preparing high-strength carbon fiber felt according to claim 1, characterized in that: In step (3), the protective atmosphere is argon containing nitrogen; preferably, the volume proportion of nitrogen in the protective atmosphere is 15-20%.

8. The process for preparing high-strength carbon fiber felt according to any one of claims 1 to 7, characterized in that: In step (3), the temperature of the hot pressing curing is 180-250° C., and the time is 4-7 hours.

9. The process for preparing high-strength carbon fiber felt according to any one of claims 1 to 7, characterized in that: In step (3), the temperature of the carbonization treatment is 900-1100°C, and the time is 1.5-3 hours.

10. The process for preparing high-strength carbon fiber felt according to any one of claims 1 to 7, characterized in that: In step (3), the graphitization treatment is performed at a temperature of 2300-2500° C. for 2.5-5 hours.

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