High-thickness glass fiber-carbon fiber composite silica aerogel felt and preparation method thereof

Abstract

The invention relates to the technical field of aerogel materials, in particular to a high-thickness glass fiber-carbon fiber composite silica aerogel felt and a preparation method thereof. According to the method provided by the invention, tetraethoxysilane is taken as a silicon source, heptaisobutyltrisilanol polyhedral oligomeric silsesquioxane (POSS) is taken as a matrix modifier, glass fibers are modified by a KH560 silane coupling agent, and carbon fibers are subjected to oxidation grafting treatment, so that strong interface bonding of the fibers and a SiO2 / POSS matrix is realized; and the silica aerogel felt with ultralow heat conductivity, high mechanical strength and excellent temperature resistance is prepared through the processes of sol preparation, gradient gelation, layered laying, felt body forming, drying post-treatment and the like. The problems that a traditional aerogel felt is low in mechanical strength, insufficient in temperature resistance, weak in matrix and fiber interface bonding force and prone to structure cracking are solved, the heat conductivity coefficient of the prepared silica aerogel felt is smaller than or equal to 0.025 W / (m.K), and the tensile strength is larger than or equal to 10 MPa.

Description

Technical Field

[0001] This application relates to the field of aerogel materials technology, and in particular to a high-thickness glass fiber-carbon fiber composite silica aerogel felt and its preparation method. Background Technology

[0002] As a new generation of ultra-insulating material, silica aerogel has an ultra-low thermal conductivity (≤0.020W / (m·K)) due to its nanoporous structure. However, pure silica aerogel has defects such as low mechanical strength, high brittleness, and easy sintering and shrinkage at high temperatures. It is usually combined with fibers to prepare aerogel felt to expand practical applications.

[0003] In existing technologies, the reinforcing fibers of aerogel felts are mostly made of single glass fibers or carbon fibers: glass fibers are inexpensive and have excellent insulation properties, but they have poor temperature resistance (easily softening above 400℃) and weak interfacial bonding with the SiO2 matrix, leading to fiber debonding over long-term use; carbon fibers are not oxidation-resistant and have high modulus, but they are more expensive and have high surface inertness, resulting in poor compatibility with the SiO2 matrix. Furthermore, the gelation process in traditional manufacturing processes often involves single acid-base reactions, which can easily lead to a loose matrix structure and uneven fiber coating; improper drying can cause the felt to shrink and crack, further reducing product performance. In addition, existing aerogel felts have insufficient high-temperature insulation performance, with thermal conductivity increasing significantly above 600℃, failing to meet the needs of high-end insulation applications such as aerospace and industrial kilns.

[0004] Therefore, it is essential to develop a method for preparing composite aerogel felt that can achieve synergistic reinforcement of glass fiber and carbon fiber, optimize the SiO2 matrix structure, and improve high-temperature thermal insulation performance. Summary of the Invention

[0005] This application provides a method for preparing a high-thickness glass fiber-carbon fiber composite silica aerogel felt, in order to solve the problem of insufficient high-temperature thermal insulation performance of existing aerogel felts in related technologies.

[0006] In a first aspect, this application provides a method for preparing a high-thickness glass fiber-carbon fiber composite silica aerogel mat, comprising the following steps: Step S101: Modify the glass fiber using a silane coupling agent to obtain modified glass fiber; Step S102: Oxidize the carbon fiber. Step S103: Tetraethyl orthosilicate and anhydrous ethanol are mixed and magnetically stirred. Deionized water is added, and then dilute hydrochloric acid is added to adjust the pH of the system to 3.0-4.0. The mixture is heated to 35-45°C and stirred to react. Then heptaisobutyltrisilyl ether cage-like polysilsesquioxane is added, and the mixture is magnetically stirred and ultrasonically treated to obtain SiO2-POSS mixed sol. Step S104: Add modified glass fiber and carbon fiber to SiO2-POSS mixed sol, disperse ultrasonically, heat to 35-45℃ for pre-gelling, then heat to 70-80℃, add ammonia to adjust the pH value to 8.0-9.0, and obtain SiO2-POSS-fiber composite gel; Step S105: Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 40-60℃ and age it for 6-24 hours. Then, immerse it in a hexane solution of methyltrimethoxysilane. After immersion, wash it. Step S106: Crush the aged SiO2-POSS-fiber composite gel, add adhesive and stir evenly, and lay it in layers of 3-5 layers, with each layer being 10-15mm thick. Then pre-needle-punch to form a felt blank with a thickness of 30-70mm. Dry under normal pressure and needle-punch a second time to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 25-60mm.

[0007] In some embodiments, the modification of glass fibers using a silane coupling agent in step S101 is as follows: the glass fibers are cut into short fibers of 20-50 mm, ultrasonically cleaned at 300-500 W for 20-30 min, vacuum dried at 50-60℃ for 2-3 h, a KH560 coupling agent solution is added, and then dilute hydrochloric acid is added to adjust the pH of the system to 3.0-4.0, and the mixture is impregnated for 1-2 h to obtain modified glass fibers. Grafting with KH560 coupling agent introduces epoxy groups onto the surface of the glass fibers, achieving chemical bonding between the glass fibers and the SiO2 / POSS matrix.

[0008] In some embodiments, the oxidation treatment of carbon fibers in step S102 involves cutting the carbon fibers into short fibers of 20-50 mm, immersing them in a nitric acid solution, rinsing them with deionized water until neutral, and then vacuum drying them at 60-70°C for 2-3 hours. Immersion in the nitric acid solution can etch active groups such as hydroxyl and carboxyl groups onto the surface of the carbon fibers, thereby improving the interfacial adhesion between the carbon fibers and the matrix.

[0009] In some embodiments, in step S103, the mass ratio of tetraethyl orthosilicate: anhydrous ethanol: deionized water: heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane is 20:13.5-23: 50-60:6-19.

[0010] In some embodiments, the mass ratio of SiO2-POSS mixed sol, modified glass fiber and carbon fiber is 0.2-0.5:2-4:1.

[0011] In some embodiments, in step S105, the amount of methyltrimethoxysilane added is 5%-8% of the mass of the SiO2-POSS-fiber composite gel.

[0012] In some embodiments, the adhesive is selected from epoxy resin or acrylic resin.

[0013] In some embodiments, in step S106, the temperature for atmospheric pressure drying is 60-80°C.

[0014] In some embodiments, in step S106, the acupuncture density of the pre-acupuncture is 100-150 needles / cm², and the acupuncture density of the secondary acupuncture is 200-250 needles / cm².

[0015] Secondly, this application also provides a high-thickness glass fiber-carbon fiber composite silica aerogel mat prepared using the above-described preparation method.

[0016] The method provided in this application uses tetraethyl orthosilicate as the silicon source and heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane (POSS) as the matrix modifier. By modifying glass fibers with KH560 silane coupling agent and performing oxidative grafting treatment on carbon fibers, a strong interfacial bond between the fibers and the SiO2 / POSS matrix is ​​achieved. Following sol preparation, gradient gelation, felt forming, and drying processes, an aerogel felt with a thickness of 25-60 mm is produced, exhibiting ultra-low thermal conductivity, high mechanical strength, and excellent temperature resistance. This application solves the problems of low mechanical strength, insufficient temperature resistance, weak interfacial bonding between the matrix and fibers, and easy cracking of traditional aerogel felts.

[0017] The beneficial effects of the technical solution provided in this application include: 1. This application uses glass fiber and carbon fiber in a mass ratio of (2-4):1 composite. Glass fiber ensures the insulation and basic mechanical properties of the felt, while carbon fiber improves the structural stability. This solves the performance shortcomings of single fiber reinforced aerogel felt, enabling the product to retain ≥80% of its strength at 300℃ and still have excellent thermal insulation at 600℃. 2. This application modifies glass fiber with KH560 coupling agent and oxidizes carbon fiber to introduce active groups on the fiber surface, thereby achieving chemical bonding between the fiber and the SiO2 / POSS matrix, avoiding the phenomenon of fiber peeling off from the matrix during use, and improving the mechanical strength and service life of the felt. 3. The cage-like structure of heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane forms a cross-linked three-dimensional interpenetrating network with SiO2, which not only improves the density and mechanical properties of the matrix, but also reduces the heat transfer path. This results in the high-thickness aerogel felt prepared in this application having a thermal conductivity ≤0.025W / (m·K), tensile strength ≥10MPa, strength retention rate ≥80% at 300℃, and thermal conductivity ≤0.06W / (m·K) at 600℃. It can be widely used in aerospace thermal protection, building energy conservation, industrial kiln insulation and other fields. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the process for preparing the glass fiber-carbon fiber composite silica aerogel mat provided in this application. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] This application provides a method for preparing glass fiber-carbon fiber composite silica aerogel felt, which can solve the problem of insufficient high-temperature thermal insulation performance of aerogel felt in the prior art.

[0022] Example 1: (1) Cut the glass fiber into short fibers of 20 mm, ultrasonically clean it with 300 W power for 30 min, vacuum dry it at 50 °C for 2 h, add KH560 coupling agent solution with a mass concentration of 3%, then add dilute hydrochloric acid to adjust the pH value of the system to 3.0, impregnate for 1 h, and obtain modified glass fiber. (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in a 6% nitric acid solution for 2 hours, rinse them with deionized water until neutral, and vacuum dry them at 70°C for 2 hours. (3) By mass, 20 parts of tetraethyl orthosilicate and 15 parts of anhydrous ethanol were mixed and stirred magnetically at 400 rpm for 15 min. 50 parts of deionized water were added and stirred for another 5 min. Then, dilute hydrochloric acid was added to adjust the pH of the system to 3.0. The mixture was heated to 35°C and stirred for 2 h. Then, 8 parts of heptaisobutyltrisilyl ether cage-like polysilsesquioxane were added and stirred magnetically at 500 rpm and ultrasonically treated at 400 W for 12 min to obtain SiO2-POSS mixed sol. (4) By mass, add 450 parts of modified glass fiber and 150 parts of carbon fiber to 30 parts of SiO2-POSS mixed sol, disperse by ultrasonication, heat to 45°C for pre-gelling, then heat to 80°C, add ammonia to adjust the pH to 9.0, and obtain SiO2-POSS-fiber composite gel. (5) Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 50℃ and age for 12h. Replace the deionized water every 6h. Then immerse it in a hexane solution of methyltrimethoxysilane (6% of the mass of SiO2-POSS-fiber composite gel) at room temperature for 2h. After immersion, wash twice with hexane. (6) The aged SiO2-POSS-fiber composite gel was crushed into 5mm particles. 3% of the composite gel mass was added with 0.8% epoxy resin adhesive and stirred evenly. Then, it was laid in 3 layers on the worktable of the needle punching machine. The thickness of each layer was 14mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 100 needles / cm² to form a 35mm thick felt blank. The felt blank was then dried at 60℃ under normal pressure for 5h. Finally, the dried felt blank was needle punched a second time at a density of 200 needles / cm² to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 28mm.

[0023] Example 1: A schematic diagram of the process for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat is shown below. Figure 1 .

[0024] Example 2: (1) Cut the glass fiber into short fibers of 20 mm, ultrasonically clean it with 400 W power for 20 min, vacuum dry it at 55 °C for 2 h, add KH560 coupling agent solution with a mass concentration of 3%, then add dilute hydrochloric acid to adjust the pH value of the system to 3.0, impregnate for 1 h, and obtain modified glass fiber. (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in a 6% nitric acid solution for 3 hours, rinse them with deionized water until neutral, and vacuum dry them at 60°C for 2 hours. (3) By mass, 30 parts of tetraethyl orthosilicate and 30 parts of anhydrous ethanol were mixed and stirred magnetically at 500 rpm for 15 min. Then, 90 parts of deionized water were added and stirred for another 5 min. Then, dilute hydrochloric acid was added to adjust the pH of the system to 3.0. The mixture was heated to 35°C and stirred for 1 h. Then, 15 parts of heptaisobutyltrisilyl ether cage-like polysilsesquioxane were added and stirred magnetically at 500 rpm and ultrasonically treated at 350 W for 10 min to obtain SiO2-POSS mixed sol. (4) By mass, 625 parts of modified glass fiber and 250 parts of carbon fiber were added to 50 parts of SiO2-POSS mixed sol, ultrasonically dispersed, heated to 40°C for pre-gelling, then heated to 75°C, and ammonia was added to adjust the pH value to 8.5 to obtain SiO2-POSS-fiber composite gel. (5) Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 45℃ and age for 18h. Replace the deionized water every 6h. Then immerse it in a hexane solution of methyltrimethoxysilane (addition amount is 5% of the mass of SiO2-POSS-fiber composite gel) and soak at room temperature for 4h. After soaking, wash with hexane 3 times. (6) The aged SiO2-POSS-fiber composite gel was crushed into 6mm particles. 3% of the composite gel mass was added with 0.6% acrylic resin adhesive and stirred evenly. Then, it was laid in 5 layers on the worktable of the needle punching machine. The thickness of each layer was 12mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 120 needles / cm² to form a felt blank with a thickness of 52mm. The felt blank was then dried at 65℃ under normal pressure for 6h. Finally, the dried felt blank was needle punched a second time at a density of 250 needles / cm² to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 47mm.

[0025] Example 3: (1) Cut the glass fiber into short fibers of 50 mm, ultrasonically clean it with 400 W power for 25 min, vacuum dry it at 60 °C for 3 h, add KH560 coupling agent solution with a mass concentration of 1.5%, then add dilute hydrochloric acid to adjust the pH value of the system to 4.0, and impregnate for 1.5 h to obtain modified glass fiber; (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in nitric acid solution with a mass concentration of 8% for 3 hours, rinse them with deionized water until neutral after soaking, and vacuum dry them at 65°C for 2 hours. (3) By mass, 30 parts of tetraethyl orthosilicate and 22.5 parts of anhydrous ethanol were mixed and magnetically stirred at 600 rpm for 12 min. 82.5 parts of deionized water were added and stirred for another 6 min. Then, dilute hydrochloric acid was added to adjust the pH of the system to 4.0. The mixture was heated to 35°C and stirred for 1 h. Then, 12 parts of heptaisobutyltrisilyl ether cage-like polysilsesquioxane were added and magnetically stirred at 500 rpm and ultrasonically treated at 300 W for 10 min to obtain SiO2-POSS mixed sol. (4) By mass, 360 parts of modified glass fiber and 120 parts of carbon fiber were added to 36 parts of SiO2-POSS mixed sol, ultrasonically dispersed, heated to 35°C for pre-gelling, then heated to 70°C, and ammonia was added to adjust the pH value to 9.0 to obtain SiO2-POSS-fiber composite gel. (5) Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 50℃ and age for 24h. Replace the deionized water every 8h. Then immerse it in a hexane solution of methyltrimethoxysilane (the amount added is 8% of the mass of SiO2-POSS-fiber composite gel) and soak at room temperature for 4h. After soaking, wash with hexane 3 times. (6) The aged SiO2-POSS-fiber composite gel was crushed into 8mm particles. 4% of the composite gel mass was added with 0.7% acrylic resin adhesive and stirred evenly. Then, it was laid in 4 layers on the worktable of the needle punching machine. The thickness of each layer was 12mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 150 needles / cm² to form a 45mm thick felt blank. The felt blank was then dried at 70℃ under normal pressure for 4h. Finally, the dried felt blank was needle punched a second time at a density of 200 needles / cm² to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 40mm.

[0026] Example 4: (1) Cut the glass fiber into short fibers of 20 mm, ultrasonically clean it with 500 W power for 30 min, vacuum dry it at 60 °C for 3 h, add KH560 coupling agent solution with a mass concentration of 2.5%, then add dilute hydrochloric acid to adjust the pH value of the system to 4.0, impregnate for 2 h, and obtain modified glass fiber. (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in nitric acid solution with a mass concentration of 8% for 4 h, rinse them with deionized water until neutral after soaking, and vacuum dry them at 65 °C for 2.5 h. (3) By mass, 40 parts of tetraethyl orthosilicate and 36 parts of anhydrous ethanol were mixed and magnetically stirred at 500 rpm for 15 min. 120 parts of deionized water were added and stirred for another 6 min. Then, dilute hydrochloric acid was added to adjust the pH of the system to 4.0. The mixture was heated to 40°C and stirred for h. Then, 30 parts of heptaisobutyltrisilyl ether cage-like polysilsesquioxane were added and magnetically stirred at 550 rpm and ultrasonically treated at 300 W for 15 min to obtain SiO2-POSS mixed sol. (4) By mass, 250 parts of modified glass fiber and 100 parts of carbon fiber were added to 40 parts of SiO2-POSS mixed sol, ultrasonically dispersed, heated to 35°C for pre-gelling, then heated to 70°C, and ammonia was added to adjust the pH value to 9.0 to obtain SiO2-POSS-fiber composite gel. (5) Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 50℃ and age for 14h. Replace the deionized water every 7h. Then immerse it in a hexane solution of methyltrimethoxysilane (the amount added is 8% of the mass of SiO2-POSS-fiber composite gel) and soak at room temperature for 3h. After soaking, wash with hexane 3 times. (6) The aged SiO2-POSS-fiber composite gel was crushed into 6mm particles. 4% of the composite gel mass was added with 0.6% epoxy resin adhesive and stirred evenly. Then, it was laid in 4 layers on the worktable of the needle punching machine. The thickness of each layer was 10mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 120 needles / cm² to form a 32mm thick felt blank. The felt blank was then dried at 60℃ under normal pressure for 5h. Finally, the dried felt blank was needle punched a second time at a density of 220 needles / cm² to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 26mm.

[0027] Example 5: (1) Cut the glass fiber into short fibers of 40 mm, ultrasonically clean it with 400 W power for 30 min, vacuum dry it at 55 °C for 2 h, add KH560 coupling agent solution with a mass concentration of 2%, then add dilute hydrochloric acid to adjust the pH value of the system to 4.0, impregnate for 2 h, and obtain modified glass fiber. (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in 6% nitric acid solution for 2.5 h, rinse them with deionized water until neutral, and vacuum dry them at 70 °C for 3 h. (3) By mass, 40 parts of tetraethyl orthosilicate and 38 parts of anhydrous ethanol are mixed and magnetically stirred at 400-600 rpm for 10-15 min. Then, 110 parts of deionized water are added and stirred for 5-10 min. After that, dilute hydrochloric acid is added to adjust the pH of the system to 3.0-4.0. The mixture is heated to 35-45℃ and stirred for 1-2 h. Then, 16 parts of heptaisobutyltrisilyl silsesquioxane cage-like polysilsesquioxane are added and magnetically stirred at 500 rpm and ultrasonically treated at 350W for 10 min to obtain SiO2-POSS mixed sol. (4) By mass, add 600 parts of modified glass fiber and 200 parts of carbon fiber to 60 parts of SiO2-POSS mixed sol, disperse by ultrasonication, heat to 35-45℃ for pre-gelling, then heat to 70-80℃, add ammonia water to adjust the pH value to 8.0-9.0, and obtain SiO2-POSS-fiber composite gel; (5) Transfer the SiO2-POSS-fiber composite gel to a constant temperature water bath at 50℃ and age for 18h. Replace the deionized water every 6h. Then immerse it in a hexane solution of methyltrimethoxysilane (8% of the mass of SiO2-POSS-fiber composite gel) at room temperature for 2h. After immersion, wash it 3 times with hexane. (6) The aged SiO2-POSS-fiber composite gel was crushed into 6mm particles. 5% of the composite gel mass was added with 0.5% epoxy resin adhesive and stirred evenly. Then, it was laid in 5 layers on the worktable of the needle punching machine. The thickness of each layer was 15mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 150 needles / cm² to form a 68mm thick felt blank. The felt blank was then dried at 80℃ under normal pressure for 4 hours. Finally, the dried felt blank was needle punched a second time at a density of 250 needles / cm² to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt with a thickness of 60mm.

[0028] Comparative Example 1: The only difference between Comparative Example 1 and Example 1 is that the glass fiber was not modified; otherwise, they are basically the same as Example 1.

[0029] Comparative Example 2: The only difference between Comparative Example 2 and Example 1 is that the carbon fiber was not oxidized; otherwise, they are basically the same as Example 1.

[0030] Comparative Example 3: (1) Cut the glass fiber into short fibers of 20 mm, ultrasonically clean it with 300 W power for 30 min, vacuum dry it at 50 °C for 2 h, add KH560 coupling agent solution with a mass concentration of 3%, then add dilute hydrochloric acid to adjust the pH value of the system to 3.0, impregnate for 1 h, and obtain modified glass fiber. (2) Cut polyacrylonitrile-based carbon fibers into short fibers of 30 mm, soak them in a 6% nitric acid solution for 2 hours, rinse them with deionized water until neutral, and vacuum dry them at 70°C for 2 hours. (3) By mass, 20 parts of tetraethyl orthosilicate and 15 parts of anhydrous ethanol were mixed and stirred magnetically at 400 rpm for 15 min. 6 parts of deionized water were added and stirred for another 5 min. Then, dilute hydrochloric acid was added to adjust the pH of the system to 3.0. The mixture was heated to 35°C and stirred for 2 h. Then, 8 parts of KH560 coupling agent were added and stirred magnetically at 500 rpm and ultrasonically treated at 400 W for 12 min to obtain SiO2 sol. (4) By mass, add 450 parts of modified glass fiber and 150 parts of carbon fiber to 30 parts of SiO2 sol, disperse by ultrasonication, heat to 45°C for pregelation, then heat to 80°C, add ammonia to adjust the pH to 9.0, and obtain SiO2-fiber composite gel. (5) Transfer the SiO2-fiber composite gel to a constant temperature water bath at 50℃ and age for 12h. Replace the deionized water every 6h. Then immerse it in a hexane solution of methyltrimethoxysilane (6% of the mass of SiO2-fiber composite gel) and soak at room temperature for 2h. After soaking, wash twice with hexane. (6) The aged SiO2-fiber composite gel was crushed into 5mm particles. 3% of the composite gel mass was added with 0.8% epoxy resin adhesive and stirred evenly. Then, it was laid in 3 layers on the worktable of the needle punching machine. The thickness of each layer was 14mm. After the laying was completed, the needle punching machine was used to pre-needle the fibers at 100 needles / cm² to make the fibers intertwine to form a 35mm thick felt blank. The felt blank was then dried at 60℃ under normal pressure for 5h. Finally, the dried felt blank was needle punched a second time at a density of 200 needles / cm² to obtain a 25mm thick glass fiber-carbon fiber composite silica aerogel felt.

[0031] The performance of the silicone aerogel mats prepared in Examples 1-5 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0032] Table 1: Performance test results of the silicone aerogel mats prepared in Examples 1-5 and Comparative Examples 1-3 ; As can be seen from the data in Table 1 of Examples 1-5 and Comparative Example 1, the tensile strength and strength retention rate at 300℃ of the aerogel felt obtained without modification of the glass fiber are both reduced. The applicant analyzed that this is because without modification of the glass fiber, no active groups were introduced on the surface of the glass fiber, resulting in a lack of chemical bonding between the glass fiber and the SiO2 / POSS matrix, weakening the interfacial bonding force, and making the fiber easy to debond.

[0033] As can be seen from the data in Examples 1-5 and Comparative Example 2 in Table 1, the tensile strength and strength retention rate at 300℃ of the aerogel felt obtained without oxidation treatment of carbon fibers are reduced. The applicant analyzed that this is because without oxidation treatment of carbon fibers, no active groups are introduced on the surface of carbon fibers, resulting in a lack of chemical bonding between carbon fibers and the SiO2 / POSS matrix, weakening the interfacial bonding force, and making the fibers easy to debond.

[0034] As can be seen from the data of Examples 1-5 and Comparative Example 3 in Table 1, the aerogel felt matrix obtained without POSS modification is loose and prone to cracking. The applicant analyzed that this is because the matrix structure is less dense due to the absence of POSS groups, making it prone to structural defects.

[0035] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0036] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this application, "a plurality of" means at least two, such as two, three, etc., unless otherwise expressly specified.

[0037] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a high-thickness glass fiber-carbon fiber composite silica aerogel mat, characterized in that, Includes the following steps: S101, modified glass fiber is obtained by modifying glass fiber with silane coupling agent; S102, an oxidation treatment is performed on the carbon fiber; S103, mix tetraethyl orthosilicate with anhydrous ethanol, stir magnetically, add deionized water, then add dilute hydrochloric acid to adjust the pH of the system to 3.0-4.0, heat to 35-45℃, stir to react, then add heptaisobutyltrisilyl alcohol cage-shaped polysilsesquioxane, stir magnetically and sonicate to obtain SiO2-POSS mixed sol; S104, modified glass fiber and carbon fiber are added to SiO2-POSS mixed sol, ultrasonically dispersed, heated to 35-45℃ for pre-gelling, then heated to 70-80℃, and ammonia water is added to adjust the pH value to 8.0-9.0 to obtain SiO2-POSS-fiber composite gel; S105, the SiO2-POSS-fiber composite gel is transferred to a constant temperature water bath at 40-60℃ and aged for 6-24 hours. Then it is immersed in a hexane solution of methyltrimethoxysilane. After immersion, it is washed. S106 involves breaking down the aged SiO2-POSS-fiber composite gel, adding adhesive and stirring evenly, laying it in 3-5 layers, then pre-needling to form a felt blank, drying under normal pressure, and then needle-punching a second time to obtain a high-thickness glass fiber-carbon fiber composite silica aerogel felt.

2. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S101, the process of modifying glass fiber with silane coupling agent is as follows: cut glass fiber into short fibers of 20-50mm, ultrasonically clean with 300-500W power for 20-30min, vacuum dry at 50-60℃ for 2-3h, add KH560 coupling agent solution, then add dilute hydrochloric acid to adjust the pH value of the system to 3.0-4.0, impregnate for 1-2h, and obtain modified glass fiber.

3. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S102, the process of oxidizing carbon fiber is as follows: the carbon fiber is cut into short fibers of 20-50mm, soaked in nitric acid solution, rinsed with deionized water until neutral after soaking, and vacuum dried at 60-70℃ for 2-3 hours.

4. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S103, the mass ratio of tetraethyl orthosilicate: anhydrous ethanol: deionized water: heptaisobutyltrisilyl alcohol cage-like polysilsesquioxane is 20:13.5-23:50-60:6-19.

5. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, The mass ratio of SiO2-POSS mixed sol, modified glass fiber, and carbon fiber is 0.2-0.5:2-4:

1.

6. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S105, the amount of methyltrimethoxysilane added is 5%-8% of the mass of the SiO2-POSS-fiber composite gel.

7. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, The adhesive is selected from epoxy resin or acrylic resin.

8. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S106, the temperature for atmospheric pressure drying is 60-80℃.

9. The method for preparing high-thickness glass fiber-carbon fiber composite silica aerogel mat according to claim 1, characterized in that, In step S106, the acupuncture density for pre-acupuncture is 100-150 needles / cm², and the acupuncture density for secondary acupuncture is 200-250 needles / cm².

10. A high-thickness glass fiber-carbon fiber composite silica aerogel mat, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

Images