Enhanced modification method of carbon fiber paper-based composite material

Abstract

The invention discloses an enhanced modification method of a carbon fiber paper-based composite material, and particularly relates to the technical field of carbon fiber paper-based composites.The method comprises the following steps that PAN-based carbon fibers are taken and cut into chopped fibers of 5-8 mm, the chopped fibers are soaked in an acetone solution with the concentration of 99.5% for 48 h, and surface oil stains and impurities are removed; according to the invention, carbon fiber plasma is subjected to activation pretreatment, coupling agent modification and rare earth oxide compounding are combined, and a high-performance fiber pretreatment process is matched, so that the binding site and interfacial compatibility between fibers and resin and between the fibers is greatly improved; the tensile strength and shear strength of the reinforced and modified carbon fiber paper-based composite material are both superior to national standard limit values, the performance of the reinforced and modified carbon fiber paper-based composite material is remarkably improved compared with that of a traditional carbon fiber paper-based composite material, a stable fiber skeleton can be formed, stress can be effectively transmitted, and then the defects that a traditional material is weak in interface bonding and insufficient in mechanical bearing are overcome.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber paper-based composite materials technology, and more specifically to a method for reinforcing and modifying carbon fiber paper-based composite materials. Background Technology

[0002] Carbon fiber paper-based composite materials are a new type of material made by using carbon fiber as the reinforcing phase, pulp fiber as the skeleton, and resin and other components, through processes such as papermaking, impregnation, and curing. They are widely used in papermaking, braking components, electronic substrates and other fields, and are high-performance composite materials that balance performance and practicality.

[0003] Currently, existing carbon fiber paper-based composite materials suffer from several drawbacks in application. Due to the strong inertness of the traditional carbon fiber surface, simple cleaning or treatment with a single coupling agent is insufficient to effectively introduce active functional groups. This results in weak interfacial bonding between the carbon fiber and other fibers, leading to delamination defects. Furthermore, the fibers cannot form a stable supporting skeleton, ultimately resulting in low tensile and shear strength. Additionally, traditional carbon fiber paper-based composite materials often rely on the frictional properties of individual fibers or resins, leading to insufficient density of the friction surface, large fluctuations in the dynamic friction coefficient, and high wear rates. Under high-temperature conditions, the fibers and resin are prone to debonding and decomposition, exhibiting poor thermal stability. Moreover, the frictional performance degrades significantly during continuous braking, making it difficult to meet the long-term use requirements of high-frequency, high-temperature braking scenarios. Therefore, this application proposes a method for reinforcing and modifying carbon fiber paper-based composite materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for reinforcing and modifying carbon fiber paper-based composite materials to address the aforementioned shortcomings in the technology.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for reinforcing and modifying carbon fiber paper-based composite materials, comprising the following steps: S1. Take PAN-based carbon fiber, cut it into short fibers of 5-8 mm, soak it in 99.5% acetone solution for 48 h to remove surface oil and impurities, place it in an ultrasonic cleaner and vibrate for 60 min, take it out and rinse it with deionized water, and put it in a forced-air drying oven to dry at 80℃ for 2 h. After drying, put it in a plasma treatment device and perform surface activation treatment at 300W power for 15-25 min under argon atmosphere to obtain pretreated carbon fiber. S2. Take cellulose fibers, add 0.05% cellulase, and enzymatically hydrolyze them at 50℃ and pH=5.0 for 30 min. Then soak them in 1% sodium hydroxide solution at 60℃ for 20 min, wash them with water until neutral, and dry them at 80℃ to obtain pretreated cellulose fibers. S3. The pretreated carbon fiber and titanate coupling agent are mixed at a mass ratio of 30:1-4, stirred and soaked in ethanol solution at room temperature for 60 min, then ultrasonically vibrated at 40℃ and 250W frequency for 60 min, and then placed in an oven to dry at 105℃ for 30 min to obtain coupling agent modified carbon fiber. S4. The coupling agent modified carbon fiber and rare earth oxide are mixed at a mass ratio of 8:1-3, and then mixed in a high-speed mixer at a speed of 1200 r / min for 15 min. After drying at 80℃ for 1 h, the mixture is placed in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fiber. S5. Take high-performance fibers and pre-treat them. After pre-treatment, mix them with the composite modified carbon fibers and pre-treated cellulose fibers and put them into a fiber disperser. Disperse them at 800 r / min for 20 min to obtain the main fiber system of pulp. S6. Mix the pulp main fiber system, foaming agent AC, foaming aid, composite modifier and water in proportion, emulsify and beat at high speed for 400-500 times, filter, dry at 80°C, and then heat at 115°C for 15 minutes to obtain the paper base preform. S7. Immerse the paper-based base preform in a phenolic resin alcohol solution, vacuum impregnate for 30 minutes, remove and air dry, and then hot-press and cure in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0006] Preferably, in step S1, the argon flow rate in the plasma processing device is 20 sccm, and the internal pressure is 10 Pa.

[0007] Preferably, the titanate coupling agent is isopropyl tritiate, and the rare earth oxide has a purity of ≥99.9% and a particle size of 5-10 μm.

[0008] Preferably, the high-performance fiber includes aramid pulp, ceramic fiber, and basalt fiber, and the preparation steps include: A1. Take the aramid pulp and put it into a 5% sodium hydroxide solution. Soak it at 70°C for 30 minutes. After surface etching, wash it with water until neutral and dry it to obtain pretreated aramid pulp. A2. The ceramic fiber wool is soaked in an ethanol solution of silane coupling agent for 40 minutes and then dried to obtain modified ceramic fiber wool. A3. After the basalt fiber is kept at 280℃ for 30 minutes, it is immersed in an ethanol solution of silane coupling agent, and then refluxed at 80℃ for 2 hours. After washing and drying, pretreated basalt fiber is obtained.

[0009] Preferably, in step S5, the composite modified carbon fiber accounts for 4% to 5% of the total fiber mass, the high-performance fiber accounts for 26% to 46% of the total fiber mass, and the cellulose fiber accounts for 10% to 30% of the total fiber mass.

[0010] Preferably, the foaming agent includes zinc oxide and zinc stearate, and the mass ratio of zinc oxide to zinc stearate is 1:1.

[0011] Preferably, in step S6, the composite modifier is prepared by mixing micron-sized lanthanum oxide and nano-sized alumina, and the preparation steps include: S6.1. Take the nano-alumina and add it to deionized water, add 0.3% sodium dodecylbenzenesulfonate as a dispersant, and ultrasonically disperse it at a frequency of 250W for 40 minutes to obtain a nano-alumina dispersion. S6.2. Take the micron-sized lanthanum oxide and add it to deionized water. Add 0.4% polymethyl methacrylate as a dispersant and ultrasonically disperse at 300W for 35 minutes to obtain a micron-sized lanthanum oxide dispersion. S6.3. The nano-alumina and micron-sized lanthanum oxide are mixed at a mass ratio of 3:6, mechanically stirred at 60°C and 500 r / min for 20 min, 0.2% triethanolamine is added as a stabilizer, and stirring is continued for 10 min to obtain the composite modifier.

[0012] Preferably, in step S7, the ethanol concentration in the phenolic resin alcohol solution is 75%, and the phenolic resin in the phenolic resin alcohol solution is cashew nut shell oil modified phenolic resin with a free formaldehyde content ≤0.1% and a curing shrinkage rate ≤1.2%.

[0013] Preferably, in step S7, the vacuum impregnation is depressurized every 10 minutes and repeated 3 times.

[0014] Preferably, in step S7, the segmented hot-press curing includes the following steps; The material was cured in stages: 120℃ / 1MPa for 3 min, 170-180℃ / 3MPa for 5 min, and 180℃ / 5MPa for 2 min. After cooling to 80℃, it was annealed at 120℃ for 2 h.

[0015] The technical effects and advantages provided by the present invention in the above technical solution are as follows: This invention, through plasma activation pretreatment of carbon fibers, combined with multi-level synergy of coupling agent modification and rare earth oxide composite, and high-performance fiber pretreatment process, significantly increases the bonding sites and interfacial compatibility between fibers and resin, and between fibers. This results in the tensile strength and shear strength of the reinforced and modified carbon fiber paper-based composite material being better than the national standard limit, and the performance is significantly improved compared with traditional carbon fiber paper-based composite materials. It can form a stable fiber skeleton, effectively transfer stress, and thus solve the shortcomings of traditional materials such as weak interfacial bonding and insufficient mechanical load-bearing capacity. This invention employs a composite modifier design of nano-alumina and micron-lanthanum oxide. The nano phase fills the pores, while the micron phase shares the frictional stress, resulting in a stable increase in the dynamic friction coefficient and a significant reduction in the wear rate. Simultaneously, the pretreated high-performance fibers and phenolic resin form a high-temperature resistant network, which allows the remaining mass at 1000℃ to remain at a high level, and the friction performance decay rate after 200 consecutive braking cycles is also greatly reduced. This effectively solves the problems of poor wear resistance, easy failure at high temperatures, and insufficient braking stability of traditional materials. This invention establishes a standardized preparation process through the coordinated operation of each step, ensuring consistent product performance. It can be implemented by adjusting existing carbon fiber paper-based composite material production lines without the need for special customized equipment, thus lowering the threshold for industrial application. Furthermore, the addition amounts of core parameters such as composite modified carbon fiber and composite modifier can be flexibly adjusted, allowing for precise adaptation to high-end heavy-duty and conventional cost-sensitive scenarios. While ensuring performance meets standards, it avoids excessive addition of expensive modifying components, achieving an optimal balance between performance and cost. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0017] Figure 1 This is a flowchart illustrating the steps of the method for reinforcing and modifying carbon fiber paper-based composite materials according to the present invention. Figure 2 This is a flowchart illustrating the steps of the high-performance fiber preparation method of the present invention. Figure 3 This is a flowchart illustrating the steps of the method for preparing the composite modifier of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figures 1-3 As shown, a method for reinforcing and modifying carbon fiber paper-based composite materials includes the following steps: S1. Take PAN-based carbon fiber, cut it into short fibers of 5-8 mm, soak it in 99.5% acetone solution for 48 h to remove surface oil and impurities, place it in an ultrasonic cleaner and vibrate for 60 min, take it out and rinse it with deionized water, and put it in a forced-air drying oven to dry at 80℃ for 2 h. After drying, put it in a plasma treatment device and perform surface activation treatment at 300W power for 15-25 min under argon atmosphere to obtain pretreated carbon fiber. In one specific embodiment of the present invention, the argon flow rate in the plasma treatment device is 20 sccm, and the internal pressure of the device during treatment is 10 Pa. By precisely controlling the degree of carbon fiber surface activation, the number of active functional groups such as hydroxyl and carboxyl groups on the surface is increased by more than 30%, which greatly increases the binding sites with coupling agents and resins.

[0020] S2. Take cellulose fibers, add 0.05% cellulase, and enzymatically hydrolyze them at 50℃ and pH=5.0 for 30 min. Then soak them in 1% sodium hydroxide solution at 60℃ for 20 min, wash them with water until neutral, and dry them at 80℃ to obtain pretreated cellulose fibers. S3. The pretreated carbon fiber and titanate coupling agent are mixed at a mass ratio of 30:1-4, stirred and soaked in ethanol solution at room temperature for 60 min, then ultrasonically vibrated at 40℃ and 250W frequency for 60 min, and then placed in an oven to dry at 105℃ for 30 min to obtain coupling agent modified carbon fiber. In one specific embodiment of the present invention, the titanate coupling agent is isopropyl tritiate, the purity of the rare earth oxide is ≥99.9%, and the particle size is 5-10μm. The functional groups of isopropyl tritiate can simultaneously bind to the carbon fiber surface and the resin. The high purity and suitable particle size of the rare earth oxide ensure uniform dispersion and synergistically enhance the interfacial bonding force.

[0021] S4. The coupling agent modified carbon fiber and rare earth oxide are mixed at a mass ratio of 8:1-3, and then mixed in a high-speed mixer at a speed of 1200r / min for 15min. After drying at 80℃ for 1h, the mixture is placed in a constant temperature oven at 115℃ for 15min to obtain composite modified carbon fiber. S5. Take high-performance fibers and pretreat them. After pretreatment, mix them with composite modified carbon fibers and pretreated cellulose fibers and put them into a fiber disperser. Disperse them at 800 r / min for 20 min to obtain the main fiber system of pulp. Composite modified carbon fiber accounts for 4% to 5% of the total fiber mass, high-performance fiber accounts for 26% to 46% of the total fiber mass, and cellulose fiber accounts for 10% to 30% of the total fiber mass.

[0022] By quantifying the proportions to balance the functions of each fiber, composite modified carbon fiber enhances strength, high-performance fiber strengthens heat and wear resistance, and cellulose fiber optimizes formability, achieving a three-in-one approach of mechanics, friction, and forming.

[0023] Furthermore, the high-performance fibers include aramid pulp, ceramic fibers, and basalt fibers, and the preparation steps include: A1. Place the aramid pulp into a 5% sodium hydroxide solution, soak at 70°C for 30 minutes, etch the surface, wash with water until neutral, and dry to obtain pretreated aramid pulp. A2. Take ceramic fiber wool, soak it in an ethanol solution of silane coupling agent for 40 minutes, and dry it to obtain modified ceramic fiber wool. A3. Basalt fibers are kept at 280℃ for 30 minutes, then immersed in an ethanol solution of silane coupling agent, and then refluxed at 80℃ for 2 hours. After washing and drying, pretreated basalt fibers are obtained.

[0024] The surface roughness is increased by alkaline etching of aramid pulp, and the compatibility is improved by grafting ceramic fiber flocking and basalt fiber coupling agent. The three work together to form a stable fiber skeleton, which enhances mechanical load-bearing capacity and thermal stability.

[0025] S6. Mix the main fiber system of pulp, foaming agent AC, foaming aid, composite modifier and water in proportion, emulsify and beat at high speed for 400-500 times, filter, dry at 80℃, and then heat at 115℃ for 15 minutes to obtain the paper base preform. In one specific embodiment of the present invention, the foaming agent includes zinc oxide and zinc stearate, and the mass ratio of zinc oxide to zinc stearate is 1:1. The two work together to optimize the foaming efficiency, so that the porosity of the preform is uniformly controlled at 35%-45%, which not only ensures the subsequent resin impregnation space, but also avoids the mechanical properties from being reduced due to excessive pores. The composite modifier is prepared by mixing micron-sized lanthanum oxide and nano-sized alumina, and the preparation steps include: S6.1. Take nano-alumina and add it to deionized water. Add 0.3% sodium dodecylbenzenesulfonate as a dispersant and ultrasonically disperse it at a frequency of 250W for 40 minutes to obtain nano-alumina dispersion. S6.2. Take micron-sized lanthanum oxide and add it to deionized water. Add 0.4% polymethyl methacrylate as a dispersant and ultrasonically disperse at 300W for 35 minutes to obtain a micron-sized lanthanum oxide dispersion. S6.3. Mix nano-alumina and micron-sized lanthanum oxide at a mass ratio of 3:6, mechanically stir at 60℃ and 500r / min for 20min, add 0.2% triethanolamine as a stabilizer, and continue stirring for 10min to obtain a composite modifier.

[0026] By filling the pores with nano-alumina and sharing the frictional stress with micron-sized lanthanum oxide, a gradient friction layer is formed, which reduces the wear rate.

[0027] S7. Immerse the paper-based base preform in a phenolic resin alcohol solution, vacuum impregnate for 30 minutes, remove and air dry, then hot press and cure in sections for 10 minutes to obtain the reinforced modified carbon fiber paper-based composite material.

[0028] In one specific embodiment of the present invention, the ethanol concentration in the phenolic resin alcohol solution is 75%, and the phenolic resin in the phenolic resin alcohol solution is cashew nut shell oil modified phenolic resin, with free formaldehyde content ≤0.1% and curing shrinkage rate ≤1.2%; vacuum impregnation is performed by releasing pressure every 10 minutes and repeating 3 times. Air is expelled from the fiber gaps through an impregnation-decompression cycle, ensuring that the resin fully penetrates into the preform and avoiding porosity defects.

[0029] The segmented hot-press curing process includes the following steps: segmented curing at 120℃ / 1MPa for 3 minutes, 170-180℃ / 3MPa for 5 minutes, and 180℃ / 5MPa for 2 minutes. After cooling to 80℃, it is then annealed at 120℃ for 2 hours.

[0030] By gradually removing low-molecular-weight volatiles through segmented curing and alleviating curing shrinkage stress, the annealing process further releases residual internal stress, preventing the material from cracking due to sudden temperature changes.

[0031] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0032] Example 1 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48h to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60min, washed with water until neutral, dried at 80℃ for 2h, and activated with argon atmosphere (20sccm, 10Pa) 300W power plasma for 20min to obtain pretreated carbon fiber. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:2 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:2 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp was immersed in a 5% sodium hydroxide solution at 70°C for 30 minutes. After surface etching, it was washed with water until neutral and dried to obtain pretreated aramid pulp. Ceramic fiber fibers were immersed in an ethanol solution of silane coupling agent for 40 minutes and dried to obtain modified ceramic fiber fibers. Basalt fibers were kept at 280°C for 30 minutes and then immersed in an ethanol solution of silane coupling agent. The mixture was then refluxed at 80°C for 2 hours and dried to obtain pretreated basalt fibers. 4.5% (total fiber mass) of composite modified carbon fiber, 16% of pretreated aramid pulp, 10% of modified ceramic fiber fibers, 15% of pretreated basalt fibers, and 20% of pretreated cellulose fibers were mixed and placed in a fiber disperser and dispersed at 800 r / min for 20 minutes to obtain the main pulp fiber system. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), composite modifier (8%) and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80°C, and then heated at 115°C for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0033] Example 2 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48h to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60min, washed with water until neutral, dried at 80℃ for 2h, and activated with argon atmosphere (20sccm, 10Pa) 300W power plasma for 20min to obtain pretreated carbon fiber. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:4 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:3 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp was immersed in a 5% sodium hydroxide solution at 70°C for 30 minutes. After surface etching, it was washed with water until neutral and dried to obtain pretreated aramid pulp. Ceramic fiber was immersed in an ethanol solution of silane coupling agent for 40 minutes and dried to obtain modified ceramic fiber. Basalt fiber was kept at 280°C for 30 minutes and then immersed in an ethanol solution of silane coupling agent. It was then refluxed at 80°C for 2 hours and dried to obtain pretreated basalt fiber. Then, 5% (total fiber mass) of composite modified carbon fiber, 26% of pretreated aramid pulp, 20% of modified ceramic fiber, 15% of pretreated basalt fiber, and 15% of pretreated cellulose fiber were mixed and placed in a fiber disperser and dispersed at 800 r / min for 20 minutes to obtain the main fiber system of pulp. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), composite modifier (10.5%) and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80°C, and then heated at 115°C for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0034] Example 3 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48h to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60min, washed with water until neutral, dried at 80℃ for 2h, and activated with argon atmosphere (20sccm, 10Pa) 300W power plasma for 20min to obtain pretreated carbon fiber. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:1 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:1 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp was immersed in a 5% sodium hydroxide solution at 70°C for 30 minutes. After surface etching, it was washed with water until neutral and dried to obtain pretreated aramid pulp. Ceramic fiber fibers were immersed in an ethanol solution of silane coupling agent for 40 minutes and dried to obtain modified ceramic fiber fibers. Basalt fibers were kept at 280°C for 30 minutes and then immersed in an ethanol solution of silane coupling agent. The mixture was then refluxed at 80°C for 2 hours and dried to obtain pretreated basalt fibers. 4% (total fiber mass) of composite modified carbon fiber, 26% of pretreated aramid pulp, 30% of modified ceramic fiber fibers, and 30% of pretreated cellulose fibers were mixed and placed in a fiber disperser and dispersed at 800 r / min for 20 minutes to obtain the main pulp fiber system. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), composite modifier (5%) and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80℃, and then heated at 115℃ for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0035] Table 1 shows the parameter differences between Examples 1-3. ; The following section provides a detailed explanation of the proportions using existing market methods: Comparative Example 1 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48 hours to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60 minutes, washed with water until neutral, and dried at 80℃ for 2 hours. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:2 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:2 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp was immersed in a 5% sodium hydroxide solution at 70°C for 30 minutes. After surface etching, it was washed with water until neutral and dried to obtain pretreated aramid pulp. Ceramic fiber fibers were immersed in an ethanol solution of silane coupling agent for 40 minutes and dried to obtain modified ceramic fiber fibers. Basalt fibers were kept at 280°C for 30 minutes and then immersed in an ethanol solution of silane coupling agent. The mixture was then refluxed at 80°C for 2 hours and dried to obtain pretreated basalt fibers. 4.5% (total fiber mass) of composite modified carbon fiber, 16% of pretreated aramid pulp, 10% of modified ceramic fiber fibers, 15% of pretreated basalt fibers, and 20% of pretreated cellulose fibers were mixed and placed in a fiber disperser and dispersed at 800 r / min for 20 minutes to obtain the main pulp fiber system. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), composite modifier (8%) and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80°C, and then heated at 115°C for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0036] Comparative Example 2 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48h to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60min, washed with water until neutral, dried at 80℃ for 2h, and activated with argon atmosphere (20sccm, 10Pa) 300W power plasma for 20min to obtain pretreated carbon fiber. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:2 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:2 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp was immersed in a 5% sodium hydroxide solution at 70°C for 30 minutes. After surface etching, it was washed with water until neutral and dried to obtain pretreated aramid pulp. Ceramic fiber fibers were immersed in an ethanol solution of silane coupling agent for 40 minutes and dried to obtain modified ceramic fiber fibers. Basalt fibers were kept at 280°C for 30 minutes and then immersed in an ethanol solution of silane coupling agent. The mixture was then refluxed at 80°C for 2 hours and dried to obtain pretreated basalt fibers. 4.5% (total fiber mass) of composite modified carbon fiber, 16% of pretreated aramid pulp, 10% of modified ceramic fiber fibers, 15% of pretreated basalt fibers, and 20% of pretreated cellulose fibers were mixed and placed in a fiber disperser and dispersed at 800 r / min for 20 minutes to obtain the main pulp fiber system. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80°C, and then heated at 115°C for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0037] Comparative Example 3 PAN-based carbon fiber was cut into 6mm short fibers, soaked in 99.5% acetone for 48h to remove oil stains, then ultrasonically vibrated at 250W / 40kHz for 60min, washed with water until neutral, dried at 80℃ for 2h, and activated with argon atmosphere (20sccm, 10Pa) 300W power plasma for 20min to obtain pretreated carbon fiber. Cellulose fibers (wood pulp fibers) were enzymatically hydrolyzed with 0.05% cellulase at 50°C and pH=5.0 for 30 min, then soaked in 1% sodium hydroxide solution at 60°C for 20 min, washed with water until neutral, and dried at 80°C to obtain pretreated cellulose fibers. Pretreated carbon fibers and titanate coupling agent were mixed at a mass ratio of 30:2 and stirred and soaked in ethanol solution at room temperature for 60 min. Then, the mixture was ultrasonically vibrated at 40℃ and 250W for 60 min. After removal, the mixture was dried in an oven at 105℃ for 30 min to obtain coupling agent modified carbon fibers. The carbon fibers were then mixed with rare earth oxides (99.9% purity, 8μm) at a mass ratio of 8:2 and mixed in a high-speed mixer at 1200r / min for 15 min. After drying at 80℃ for 1 h, the mixture was heated in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fibers. Aramid pulp (16%), ceramic fiber fluff (10%), and basalt fiber (15%) were directly mixed with 4.5% (total fiber mass) of composite modified carbon fiber and 20% of pretreated cellulose fiber and placed in a fiber disperser. The mixture was dispersed at 800 r / min for 20 min to obtain the main fiber system of pulp. The pulp fiber system, foaming agent AC (4% of total amount), foaming aid (zinc stearate and zinc oxide 1:1, accounting for 3% of total amount), composite modifier (8%) and water (9 times the total amount) are mixed, emulsified and beaten at high speed for 450 times, filtered, dried at 80°C, and then heated at 115°C for 15 minutes to obtain the paper base preform. The paper-based preform is immersed in a phenolic resin alcohol solution, vacuum impregnated for 30 minutes, then removed and dried, and then hot-pressed in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

[0038] Table 2 shows the parameter differences between comparative examples 1-3. ; The performance of the above-mentioned reinforced and modified carbon fiber paper-based composite material was tested.

[0039] The testing indicators and standards include: tensile strength (GB / T 1447-2005), shear strength (GB / T 1450.1-2005), friction performance (GB / T 13826-2008, 1000r / min, 0.5MPa), thermal stability (GB / T 30711-2014, 1000℃), free formaldehyde (GB / T 24411-2009), and braking stability (simulated continuous braking 200 times), all of which adopt industry standard testing methods.

[0040] Table 3 shows the performance test results of Examples 1-3 and Comparative Examples 1-3.

[0041] ; Analyze the data in the table above: As shown in the table above, the tensile strength of Examples 1-3 ranges from 48.6 to 55.7 MPa, and the shear strength ranges from 3.5 to 4.1 MPa, all of which meet and exceed the national standard requirements of tensile strength ≥48 MPa and shear strength ≥3.5 MPa. In contrast, Comparative Example 1, without plasma treatment, has a tensile strength of only 36.8 MPa and a shear strength of 2.2 MPa, representing decreases of 30% and 42.1% respectively compared to Example 1. Comparative Example 3 (high-performance fiber without pretreatment) has a tensile strength of 39.5 MPa and a shear strength of 2.4 MPa, representing decreases of 24.5% and 36.8% respectively compared to Example 1. Therefore, Examples 1-3 activate the carbon fiber surface through argon plasma, thereby enhancing the surface activity of functional groups such as hydroxyl and carboxyl groups. The number of fibers increased by more than 30%, significantly increasing the bonding sites between carbon fibers and titanate coupling agents and phenolic resins, reducing interfacial defects, and thus significantly improving tensile and shear strength. In Comparative Example 1, due to the absence of this step, the carbon fiber surface was smooth, the interfacial bonding force was weak, and interfacial delamination easily occurred under stress, resulting in a sharp drop in mechanical properties. In addition, through the synergistic effect of high-performance fiber pretreatment, the alkaline etching of aramid pulp and the silane coupling agent grafting of ceramic fibers and basalt fibers in the examples increased the surface roughness of the fibers, enhanced the interweaving and winding ability with the main fiber system of pulp, and formed a stable fiber skeleton. In Comparative Example 3, the untreated fiber surface was highly inert, the bonding force with other components was poor, and it could not effectively transfer stress, resulting in a significant decline in mechanical properties.

[0042] Furthermore, Example 2, with a tensile strength of 55.7 MPa and a shear strength of 4.1 MPa, is the optimal result. This is because the proportion of composite modified carbon fiber in this example is increased to 5% (total fiber mass), and the mass ratio of carbon fiber to coupling agent is increased to 30:4, while the mass ratio of coupling agent-modified carbon fiber to rare earth oxides reaches 8:3. The multiple modifications synergistically enhance the interfacial bonding and fiber skeleton support. Example 3, with a tensile strength of 48.6 MPa and a shear strength of 3.5 MPa, just meets the minimum requirements of the claims. This is because the proportion of composite modified carbon fiber is 4%, and the amount of coupling agent and rare earth oxide added is the lowest. Although the performance meets the requirements, the redundancy is small. The dynamic friction coefficients of Examples 1-3 remained stable at 0.13-0.15, with a significantly reduced wear rate. In contrast, Comparative Example 2 (without composite modifier) ​​had a dynamic friction coefficient of only 0.10 and a wear rate as high as 5.9 × 10⁻⁶. -7 cm 3 / J, the wear rate increased by 156.5% compared to Example 1, and the wear rate of Comparative Example 1 was 6.8 × 10. -7 cm 3 / J increased by 195.7% compared to Example 1. Therefore, through the gradient strengthening effect of the composite modifier, the tiny pores of the base preform can be filled, the density of the friction surface can be improved, and it can also act as a hard point to evenly distribute the friction stress, reducing material loss during the friction process. The two work together to stabilize the friction coefficient in the range of 0.12-0.16 suitable for heavy-load braking, while reducing the wear rate. However, in Comparative Example 2, which lacks the composite modifier, the friction surface relies solely on the properties of the fiber and resin. The fiber is easily worn off, and the resin is easily softened and melted, resulting in a low and unstable friction coefficient and a sharp increase in the wear rate. Furthermore, in Comparative Example 1, due to insufficient surface activity of the carbon fiber, the bond with the resin is not tight, and the fiber-resin interface is easily peeled off during the friction process, generating a large amount of wear debris, which further aggravates the wear. The remaining mass of Examples 1-3 under static air atmosphere at 1000℃ was 79.1%-84.3%, with Example 2 reaching 84.3%. The remaining mass of Comparative Examples 1-3 at 1000℃ was only 65.7%-68.2%, a decrease of 20.4%, 17.3%, and 18.3% respectively compared to Example 1. This shows the role of the high-temperature resistant skeleton of the high-performance fiber: the pretreated aramid pulp and basalt fiber in the examples have excellent high-temperature resistance, and the interface bonding with phenolic resin is tighter after pretreatment. It is not easy to debond and decompose under high temperature environment, forming a stable high-temperature resistant support skeleton. In contrast, the untreated high-performance fiber in Comparative Example 3 has weak bonding force with resin, and is easy to debond and peel off at high temperature, resulting in material structure collapse and aggravated mass loss. The friction performance degradation rate after 200 consecutive braking cycles in Examples 1-3 was only 3.8%-4.8%, with Example 2 showing the lowest at 3.8%. The degradation rates in Comparative Examples 1-3 were as high as 15.3%-18.5%, representing increases of 340.5%, 264.3%, and 297.6% respectively compared to Example 1. Therefore, the segmented hot-pressing curing and low-temperature annealing process used in these examples, with the first step of holding at 120℃ / 1MPa for 3 minutes, effectively removes low-molecular-weight volatiles from the resin, preventing instability of the friction surface due to the overflow of high-temperature volatiles during braking. The second step, holding at 175℃ / 3... The process involves holding the resin at 5 MPa for 5 minutes to achieve slow curing and reduce internal stress caused by curing shrinkage. The third step involves holding the resin at 180℃ / 5 MPa for 2 minutes to densify the material structure. Finally, annealing at 120℃ for 2 hours (cooling rate 2℃ / min) can further release residual internal stress, ensuring the stability of the material structure during braking and slow decay of friction performance. In contrast, the comparative example lacks a core modification process, resulting in a large number of interface defects and internal stresses inside the material. During continuous braking, repeated temperature changes and stress will exacerbate the expansion of defects, leading to large fluctuations in the coefficient of friction and a sharp increase in the decay rate. This invention forms a standardized preparation process through the coordinated operation of each step, ensuring consistent product performance. It can be implemented by adjusting existing carbon fiber paper-based composite material production lines without the need for special customized equipment, thus lowering the threshold for industrial application.

[0043] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for reinforcing and modifying carbon fiber paper-based composite materials, characterized in that, Includes the following steps: S1. Take PAN-based carbon fiber, cut it into short fibers of 5-8 mm, soak it in 99.5% acetone solution for 48 h to remove surface oil and impurities, place it in an ultrasonic cleaner and vibrate for 60 min, take it out and rinse it with deionized water, and put it in a forced-air drying oven to dry at 80℃ for 2 h. After drying, put it in a plasma treatment device and perform surface activation treatment at 300W power for 15-25 min under argon atmosphere to obtain pretreated carbon fiber. S2. Take cellulose fibers, add 0.05% cellulase, and enzymatically hydrolyze them at 50℃ and pH=5.0 for 30 min. Then soak them in 1% sodium hydroxide solution at 60℃ for 20 min, wash them with water until neutral, and dry them at 80℃ to obtain pretreated cellulose fibers. S3. The pretreated carbon fiber and titanate coupling agent are mixed at a mass ratio of 30:1-4, stirred and soaked in ethanol solution at room temperature for 60 min, then ultrasonically vibrated at 40℃ and 250W frequency for 60 min, and then placed in an oven to dry at 105℃ for 30 min to obtain coupling agent modified carbon fiber. S4. The coupling agent modified carbon fiber and rare earth oxide are mixed at a mass ratio of 8:1-3, and then mixed in a high-speed mixer at a speed of 1200 r / min for 15 min. After drying at 80℃ for 1 h, the mixture is placed in a constant temperature oven at 115℃ for 15 min to obtain composite modified carbon fiber. S5. Take high-performance fibers and pre-treat them. After pre-treatment, mix them with the composite modified carbon fibers and pre-treated cellulose fibers and put them into a fiber disperser. Disperse them at 800 r / min for 20 min to obtain the main fiber system of pulp. S6. Mix the pulp main fiber system, foaming agent AC, foaming aid, composite modifier and water, emulsify and beat at high speed for 400-500 times, filter, dry at 80°C, and then heat at 115°C for 15 minutes to obtain the paper base preform. S7. Immerse the paper-based base preform in a phenolic resin alcohol solution, vacuum impregnate for 30 minutes, remove and air dry, and then hot-press and cure in sections for 10 minutes to obtain a reinforced modified carbon fiber paper-based composite material.

2. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S1, the argon flow rate in the plasma processing device is 20 sccm, and the internal pressure is 10 Pa.

3. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that: The titanate coupling agent is isopropyl tritiate, and the rare earth oxide has a purity of ≥99.9% and a particle size of 5-10 μm.

4. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that: The high-performance fibers include aramid pulp, ceramic fibers, and basalt fibers, and the preparation steps include: A1. Take the aramid pulp and put it into a 5% sodium hydroxide solution. Soak it at 70°C for 30 minutes. After surface etching, wash it with water until neutral and dry it to obtain pretreated aramid pulp. A2. The ceramic fiber wool is soaked in an ethanol solution of silane coupling agent for 40 minutes and then dried to obtain modified ceramic fiber wool. A3. After the basalt fiber is kept at 280℃ for 30 minutes, it is immersed in an ethanol solution of silane coupling agent, and then refluxed at 80℃ for 2 hours. After washing and drying, pretreated basalt fiber is obtained.

5. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S5, the composite modified carbon fiber accounts for 4% to 5% of the total fiber mass, the high-performance fiber accounts for 26% to 46% of the total fiber mass, and the cellulose fiber accounts for 10% to 30% of the total fiber mass.

6. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that: The foaming agent includes zinc oxide and zinc stearate, and the mass ratio of zinc oxide to zinc stearate is 1:

1.

7. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S6, the composite modifier is prepared by mixing micron-sized lanthanum oxide and nano-sized alumina, and the preparation steps include: S6.

1. Take the nano-alumina and add it to deionized water, add 0.3% sodium dodecylbenzenesulfonate as a dispersant, and ultrasonically disperse it at a frequency of 250W for 40 minutes to obtain a nano-alumina dispersion. S6.

2. Take the micron-sized lanthanum oxide and add it to deionized water. Add 0.4% polymethyl methacrylate as a dispersant and ultrasonically disperse at 300W for 35 minutes to obtain a micron-sized lanthanum oxide dispersion. S6.

3. The nano-alumina and micron-sized lanthanum oxide are mixed at a mass ratio of 3:6, mechanically stirred at 60°C and 500 r / min for 20 min, 0.2% triethanolamine is added as a stabilizer, and stirring is continued for 10 min to obtain the composite modifier.

8. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S7, the ethanol concentration in the phenolic resin alcohol solution is 75%, and the phenolic resin in the phenolic resin alcohol solution is cashew nut shell oil modified phenolic resin with free formaldehyde content ≤0.1% and curing shrinkage rate ≤1.2%.

9. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S7, the vacuum impregnation is depressurized every 10 minutes and repeated 3 times.

10. The method for reinforcing and modifying carbon fiber paper-based composite materials according to claim 1, characterized in that, In step S7, the segmented hot-press curing includes the following steps; The material was cured in stages: 120℃ / 1MPa for 3 min, 170-180℃ / 3MPa for 5 min, and 180℃ / 5MPa for 2 min. After cooling to 80℃, it was annealed at 120℃ for 2 h.

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