Aerogel composite fiber material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of aerogel composite materials, and discloses an aerogel composite fiber material and a preparation method and application thereof.The aerogel composite fiber material comprises, by weight, 15-50% of polysilazane fibers and 50-85% of a silicon dioxide aerogel matrix, the polysilazane fibers and the silicon dioxide aerogel matrix are connected through Si-O-Si chemical bonding, and an inert passivation layer is arranged at the interface of the two. The preparation method comprises the following steps: immersing the polysilazane fiber in silicon source precursor sol to carry out in-situ catalytic gelation; carrying out gas phase treatment on the obtained alcogel composite material, and forming an inert passivation layer on the surface of the fiber by utilizing a generated by-product; and carrying out normal-pressure drying on the composite material subjected to gas phase treatment. Through in-situ catalysis and interface self-passivation design, the interface bonding strength and the mechanical property of the material are remarkably enhanced, normal-pressure drying of the material is achieved through gas phase treatment, the process is simplified, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogel composite materials, in particular to an aerogel composite fiber material and a preparation method and application thereof. BACKGROUND

[0002] Silica aerogel has a wide application prospect in the fields of aerospace, industrial thermal insulation and building energy saving due to its three-dimensional nano-porous network structure, which exhibits extremely low thermal conductivity and bulk density. However, the pure silica aerogel material is brittle and has low mechanical strength, which limits its application in load-bearing or complex working conditions. In order to improve its mechanical properties, the method of fiber reinforcement is usually used to prepare aerogel composites.

[0003] In the prior art, the reinforcing fibers are mostly quartz fibers or glass fibers with stable chemical properties. Such fibers can only form physical contact with the silica aerogel matrix, and the interfacial bonding force is weak. When the composite material is subjected to external force, the stress is difficult to be effectively transmitted from the matrix to the reinforcing fibers, resulting in easy debonding at the interface and limited improvement of the overall mechanical properties of the material.

[0004] In addition, the preparation process of traditional aerogels usually requires supercritical drying technology to remove the solvent inside the gel to maintain its porous structure from collapsing. The supercritical drying process has high equipment requirements and harsh operating conditions, accompanied by high energy consumption and production cost. Although the atmospheric drying process can significantly reduce the cost, the huge capillary force generated during the solvent evaporation process will directly lead to serious shrinkage and cracking of the gel skeleton, resulting in a dense material with high density and low porosity, which loses the performance advantages of aerogels. Therefore, it is a technical problem to be solved in the field to develop an aerogel composite material that can realize strong interfacial bonding and be prepared by low-cost atmospheric drying process. SUMMARY

[0005] The existing preparation technology of aerogel composites has the following disadvantages: 1. The reinforcing fibers and the aerogel matrix are usually physically mixed, the interfacial bonding depends on physical adsorption, the mechanical property transmission efficiency is limited, and the interface is prone to delamination under stress; 2. In order to obtain aerogels with low shrinkage, supercritical drying technology is usually required in the preparation process, which has high equipment cost, high energy consumption and high requirements for operating environment; 3. The interface between the fiber and the matrix may be chemically unstable in subsequent processing or application environment.

[0006] The present application aims to provide an aerogel composite fiber material and a preparation method and application thereof to solve the above technical problems.

[0007] To solve the above technical problems, the present application provides the following technical solutions. The present application provides in a first aspect an aerogel composite fiber material comprising polysilazane fibers and a silica aerogel matrix surrounding the polysilazane fibers.

[0008] The content of the polysilazane fibers is 15-50% by weight, and the content of the silica aerogel matrix is 50-85% by weight.

[0009] The polysilazane fibers and the silica aerogel matrix are connected by chemical bonding. An inert passivation layer is provided at the interface between the polysilazane fibers and the silica aerogel matrix.

[0010] In a preferred embodiment, the inert passivation layer is a product generated by the reaction of an acidic substance with the surface of the polysilazane fibers.

[0011] The present application provides in a second aspect a preparation method for the aerogel composite fiber material as described in the first aspect, comprising the following steps: S1, in-situ catalytic gelation: the polysilazane fibers are immersed in a silica source precursor sol. Without additional catalyst, the surface of the polysilazane fibers reacts with water in the silica source precursor sol to release ammonia. The ammonia acts as a catalyst to initiate the hydrolysis and condensation reactions of the silica source precursor sol, forming an alcohol gel composite material.

[0012] S2, gas phase treatment: the alcohol gel composite material is placed in a sealed reactor, and a carrier gas containing dimethyldichlorosilane is first introduced at a temperature of 65-85°C for gas phase pinning enhancement treatment. The dimethyldichlorosilane reacts with the hydroxyl groups in the alcohol gel composite material to generate hydrogen chloride as a byproduct. After the treatment is completed, the introduction of the carrier gas containing dimethyldichlorosilane is stopped and the reactor is kept sealed for 45-90 minutes. During this sealed reaction stage, the hydrogen chloride byproduct reacts with the surface of the polysilazane fibers to form the inert passivation layer.

[0013] S3, normal pressure drying: the composite material treated in step S2 is subjected to heating and drying at normal pressure.

[0014] In a preferred embodiment, in step S1, the silica source precursor sol is prepared from tetraethyl orthosilicate, anhydrous ethanol and deionized water in a molar ratio of 1:(15-35):(5-8).

[0015] In a preferred embodiment, in step S1, after the alcohol gel composite material is formed, a step of aging in a constant temperature environment of 25-45°C for 18-30 hours is further included.

[0016] In a preferred embodiment, in step S2, the volume concentration of dimethyldichlorosilane in the carrier gas containing dimethyldichlorosilane is 8-18 vol%.

[0017] In a preferred embodiment, in step S2, the duration of the gas phase pinning enhancement treatment is 1.5-3.5 hours.

[0018] In a preferred embodiment, in step S2, the carrier gas is nitrogen.

[0019] In a preferred embodiment, the polysilazane fiber is prepared by the following method: The dimethylchlorosilane is reacted with ammonia to obtain a liquid polysilazane precursor, the liquid polysilazane precursor is melt spun, and crosslinking and curing are performed under the conditions of a temperature of 150-220℃ and a relative humidity of 70%-90% to obtain the polysilazane fiber.

[0020] In a preferred embodiment, in step S3, the specific procedure of the normal pressure drying is as follows: Raising the temperature to 70℃ at a rate of 1℃ / min and maintaining the temperature for 2-4 hours, and then raising the temperature to 110-150℃ at a rate of 1℃ / min and maintaining the temperature for 4-6 hours.

[0021] The third aspect of the present application provides an application of the aerogel composite fiber material according to the first aspect, and the application is in the fields of aerospace, building insulation, industrial pipeline heat insulation, and new energy.

[0022] The present application provides an aerogel composite fiber material, a preparation method thereof, and an application thereof. 1. The present application forms Si-O-Si chemical bonding between the polysilazane fiber and the silica aerogel matrix through in-situ catalytic gelation, which improves the transmission efficiency of the interface bonding strength and mechanical properties compared to the physical mixing method.

[0023] 2. The present application enhances the skeleton strength of the alcohol gel and makes it hydrophobic through gas phase treatment, so that subsequent normal pressure drying can be used, replacing the high-cost and high-energy consumption supercritical drying process, simplifying the preparation process and reducing the production cost.

[0024] 3. The hydrogen chloride by-product generated by the gas phase pinning enhancement treatment is used for interface passivation of the polysilazane fiber in the subsequent closed reaction stage, which converts the reaction by-product into a functional reagent and simultaneously completes the skeleton enhancement, hydrophobic modification, and interface stabilization in one integrated step, improving the atomic economy of the process and the interface stability of the final product. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments, comparative examples and test examples of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0026] The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows, and the reagents not specifically described are commercially available analytical pure or higher grade products.

[0027] Dichloromethylsilane, CAS No. 75-54-7; Ammonia, CAS No. 7664-41-7; Anhydrous toluene, CAS No. 108-88-3; Tetraethyl orthosilicate, CAS No. 78-10-4; Anhydrous ethanol, CAS No. 64-17-5; Dimethyldichlorosilane, CAS No. 75-78-5.

[0028] Example 1-3: General preparation step of polysilazane fiber in the examples: Dichloromethylsilane and ammonia were reacted in anhydrous toluene to obtain a liquid polysilazane precursor, and then the liquid polysilazane precursor was melt-spun to obtain a fiber assembly. The fiber assembly was cross-linked and cured under the condition of a specific temperature and relative humidity to obtain a polysilazane fiber. Example 1:

[0029] 1. Preparation of polysilazane fiber: According to the general preparation step, dichloromethylsilane and ammonia were reacted in anhydrous toluene to obtain a liquid polysilazane precursor, and then the liquid polysilazane precursor was melt-spun to obtain a fiber assembly. The fiber assembly was cross-linked and cured under the condition of a temperature of 150°C and a relative humidity of 70% to obtain a polysilazane fiber.

[0030] 2. Preparation of aerogel composite fiber material: S1, in-situ catalytic gelation: a silicon source precursor sol was prepared according to a molar ratio of tetraethyl orthosilicate: anhydrous ethanol: deionized water of 1:15:5, and the polysilazane fiber prepared in step 1 was immersed in the silicon source precursor sol, and was aged at 25°C for 18 hours in a constant temperature environment to form an alcohol gel composite material.

[0031] S2, gas phase treatment: the obtained alcohol gel composite material was placed in a closed reactor, and dimethyldichlorosilane-containing nitrogen gas with a volume concentration of 8 vol% was introduced at a temperature of 65°C for gas phase pinning enhancement treatment for 1.5 hours; then the introduction of dimethyldichlorosilane-containing nitrogen gas was stopped and the closed reaction was maintained for 45 minutes.

[0032] S3, atmospheric pressure drying: the composite material treated in step S2 was heated to 70°C at a rate of 1°C / min and kept constant for 2 hours, and then heated to 110°C at a rate of 1°C / min and kept constant for 4 hours.

[0033] Sample S1 was obtained. It was determined that in the obtained sample S1, the weight percentage of polysilazane fibers was 15%, and the weight percentage of silica aerogel matrix was 85%. Example 2:

[0034] 1. Preparation of polysilazane fibers: According to the general preparation procedure, dichloromethylsilane was reacted with ammonia gas in anhydrous toluene to obtain a liquid polysilazane precursor, and then the liquid polysilazane precursor was subjected to melt spinning to obtain a fiber assembly. The fiber assembly was crosslinked and cured at a temperature of 185°C and a relative humidity of 80% to obtain polysilazane fibers.

[0035] 2. Preparation of aerogel composite fiber material: S1, in-situ catalytic gelation: a silica source precursor sol was prepared according to a molar ratio of tetraethyl orthosilicate: anhydrous ethanol: deionized water of 1:25:6.5, and the polysilazane fibers prepared in step 1 were immersed in the silica source precursor sol, and the alcohol gel composite material was formed by aging in a constant temperature environment at 35°C for 24 hours.

[0036] S2, gas phase treatment: the obtained alcohol gel composite material was placed in a closed reactor, and dimethyldichlorosilane-containing nitrogen gas with a volume concentration of 13 vol% was introduced at a temperature of 75°C for gas phase pinning enhancement treatment for 2.5 hours; then the introduction of dimethyldichlorosilane-containing nitrogen gas was stopped and the closed reaction was maintained for 67.5 minutes.

[0037] S3, atmospheric pressure drying: the composite material treated in step S2 was heated to 70°C at a rate of 1°C / min and kept constant for 3 hours, and then heated to 130°C at a rate of 1°C / min and kept constant for 5 hours.

[0038] Sample S2 was obtained. It was determined that in the obtained sample S2, the weight percentage of polysilazane fibers was 30%, and the weight percentage of silica aerogel matrix was 70%. Example 3:

[0039] 1. Preparation of polysilazane fibers: According to the general preparation procedure, dichloromethylsilane was reacted with ammonia gas in anhydrous toluene to obtain a liquid polysilazane precursor, which was then melt-spun to obtain a fiber assembly. The fiber assembly was crosslinked and cured under the conditions of a temperature of 220°C and a relative humidity of 90% to obtain a polysilazane fiber.

[0040] 2. Preparation of aerogel composite fiber material: S1, in-situ catalytic gelation: a silica source precursor sol was prepared according to a molar ratio of tetraethyl orthosilicate: anhydrous ethanol: deionized water of 1:35:8, and the polysilazane fiber prepared in step 1 was immersed in the silica source precursor sol, which was aged for 30 hours in a constant temperature environment of 45°C to form an alcohol gel composite material.

[0041] S2, gas phase treatment: the obtained alcohol gel composite material was placed in a sealed reactor, and nitrogen gas containing dimethyldichlorosilane with a volume concentration of 18 vol% was introduced at a temperature of 85°C for gas phase pinning enhancement treatment for 3.5 hours; then the introduction of nitrogen gas containing dimethyldichlorosilane was stopped and the sealed reaction was maintained for 90 minutes.

[0042] S3, atmospheric pressure drying: the composite material treated in step S2 was heated to 70°C at a rate of 1°C / min and kept at this temperature for 4 hours, and then heated to 150°C at a rate of 1°C / min and kept at this temperature for 6 hours.

[0043] Sample S3 was obtained. It was determined that in the obtained sample S3, the weight percentage of polysilazane fiber was 50%, and the weight percentage of silica aerogel matrix was 50%.

[0044] Comparative Examples 1-3: Comparative Example 1: Compared with Example 2, the difference lies in that the polysilazane fiber in step S1 is replaced by an equal mass of ordinary quartz fiber, and the rest of the preparation steps and parameters are the same.

[0045] Comparative Example 2: Compared with Example 2, the difference lies in that after the gas phase pinning enhancement treatment in step S2, the step of maintaining the sealed reaction is omitted, and the rest of the preparation steps and parameters are the same.

[0046] Comparative Example 3: Compared with Example 2, the difference lies in that the gas phase treatment of step S2 is omitted, and the rest of the preparation steps and parameters are the same.

[0047] Test Examples 1-3: Test Example 1: Performance Test Test Method: The samples S1-S3 and D1-D3 prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to the following performance tests under the same environment.

[0048] Bulk density test: The length, width and height of the sample to be tested were measured using an electronic caliper, and each dimension was measured three times to obtain an average value. The volume (V) of the sample was calculated. The mass (m) of the sample was measured using an electronic balance with a precision of 0.0001 g. The bulk density of the sample was calculated by the formula p = m / V. Three parallel samples were tested for each sample, and the results were averaged.

[0049] Thermal conductivity test: A transient plane source method thermal conductivity tester was used to test the thermal conductivity of the sample under the conditions of an ambient temperature of 25°C and a relative humidity of 50%. The probe was placed between two identical samples, and a slight pressure was applied to ensure contact. The test program was started, and the stable thermal conductivity value was recorded. Three parallel samples were tested for each sample, and the results were averaged.

[0050] Compression performance test: A universal material testing machine was used to place a sample with dimensions of 20 mm x 20 mm x 10 mm between two parallel compression plates. The sample was subjected to uniaxial compression at a constant loading rate of 2 mm / min. The stress-strain curve was recorded, and the compression stress value corresponding to a compression strain of 50% was extracted. Three parallel samples were tested for each sample, and the results were averaged.

[0051] Static water contact angle test: A contact angle measuring instrument was used to test under the conditions of an ambient temperature of 25°C and a relative humidity of 50%. The sample was placed on the sample stage, and a 5 μL droplet of deionized water was dropped onto the sample surface using a microsyringe. After the water droplet was dropped for 30 seconds, an image of the water droplet on the sample surface was taken, and its static contact angle was measured. Five measurements were made at different locations for each sample, and the results were averaged.

[0052] Test results: Table 1. Performance test results of each sample

[0053] Result analysis: From the test data in Table 1, it can be seen that the bulk density and thermal conductivity of samples S1-S3 are at a relatively low level, and the static water contact angle is greater than 140°. In contrast, the bulk density and thermal conductivity of sample D3 are significantly higher than those of S1-S3, and the static water contact angle is less than 10°. The reason for this phenomenon is that the preparation method of S1-S3 includes a gas phase treatment step, which makes the surface of the alcohol gel skeleton hydrophobic, effectively resisting the capillary force caused by solvent evaporation during normal pressure drying, thereby maintaining the porous network structure. The preparation method of D3 lacks this gas phase treatment step, resulting in a serious collapse of the alcohol gel structure during normal pressure drying, forming a dense material.

[0054] Comparing the data of samples S2 and D1, both have a low bulk density and a high static water contact angle, but the compressive stress of S2 at 50% strain is much higher than that of D1. This is because the preparation method of S2 uses polysilazane fibers, which form Si-O-Si chemical bonds with the silicon source precursor during the in-situ catalytic gelation step. The quartz fibers used in D1 do not participate in the reaction and only form physical contact with the matrix. The chemical bonded interface can effectively transfer stress between the fiber and the matrix, so S2 shows a higher compressive stress.

[0055] Comparing the data of samples S2 and D2, both have similar low bulk density and high static water contact angle, but the compressive stress of S2 at 50% strain is higher than that of D2. In the preparation method of S2, the gas phase treatment step includes a subsequent closed reaction stage. During this stage, the hydrogen chloride by-product generated in the previous reaction reacts with the surface of the polysilazane fiber, forming an inert passivation layer. The preparation method of D2 omits this closed reaction stage and fails to form this passivation layer. The inert passivation layer enhances the interface region between the fiber and the matrix, allowing S2 to achieve a higher compressive stress.

[0056] Test Example 2: Thermal Stability Test Test Method: This test aims to evaluate the thermal decomposition behavior of the composite material. A thermogravimetric analyzer is used to test the sample.

[0057] Sample Preparation: Samples are taken from the center of samples S2 and D1, with a mass control of 5-10 mg.

[0058] Test Procedure: Place the sample in an alumina crucible and put it into the thermogravimetric analyzer. Heat from 30°C to 800°C at a rate of 10°C / min under a high-purity nitrogen atmosphere with a flow rate of 50 mL / min.

[0059] Data Recording: Record the curve of the mass of the sample versus temperature, and determine the temperature corresponding to a 5% weight loss of the sample at which temperature as the onset temperature of thermal decomposition of the material. The residual mass percentage of the sample at 800℃ was also recorded.

[0060] Test results: Table 2. Test results of thermogravimetric analysis (TGA) of samples

[0061] Result analysis: From the test data in Table 2, it can be seen that the thermal decomposition onset temperature of sample S2 is higher than that of sample D1. This data indicates that the composite material using polysilazane fibers has a higher temperature at which mass loss begins to occur under the action of heat. Although the residual mass of sample D1 at 800℃ is slightly higher, this is related to the fact that the quartz fiber itself does not undergo mass change within the test temperature range, but its lower thermal decomposition onset temperature indicates the presence of regions with poor thermal stability in its composite structure.

[0062] The mechanism of this phenomenon lies in the differences in the composition and interface structure of the material. Sample S2 uses polysilazane fibers, and during the in-situ catalytic gelation process, the reactive functional groups on its surface react with the silica matrix precursor to form Si-O-Si chemical bonds. This chemically bonded interface forms a thermodynamically stable connection, making the entire composite material system less likely to decompose under the action of heat.

[0063] On the contrary, sample D1 uses quartz fibers, which are chemically inert, and only forms physical contact with the silica matrix, with weak interfacial bonding. The physical interface or residual organic groups that may exist near the interface become structural thermal weak points, causing the material to begin to lose mass at a relatively low temperature. Therefore, by using polysilazane fibers to form a chemically bonded structure with the matrix, the thermal stability of the composite material is effectively improved.

[0064] Test Example 3: Performance retention rate test after high temperature treatment Test method: This test aims to evaluate the ability of the composite material to maintain its macroscopic structural integrity and mechanical properties after being subjected to a high temperature environment.

[0065] High temperature treatment: Place samples S2 and D1 (size 20mm x 20mm x 10mm) in a muffle furnace, heat to 600℃ at a rate of 5℃ / min in an air atmosphere, and maintain at this temperature for 2 hours, then naturally cool to room temperature with the furnace. The treated samples are denoted as S2' and D1', respectively.

[0066] Performance characterization: Visual observation: Observe and record the macroscopic morphology of samples S2' and D1', check for the presence of cracks, pulverization, or obvious volume shrinkage.

[0067] Compression performance test: The samples S2' and D1' were tested according to the compression performance test method disclosed in Test Example 1 to obtain the compression stress at 50% strain.

[0068] Performance retention rate calculation: Compression stress retention rate (%) = (compression stress after high temperature treatment / compression stress before treatment) x 100%.

[0069] Test results: Table 3. Performance comparison of samples before and after high temperature treatment Sample No. Compressive Stress Before Treatment (kPa) Appearance After Treatment Compressive Stress After Treatment (kPa) Compressive Stress Retention Rate (%) S2 142 No crack 131 92.3 D1 35 Micro crack on surface 12 34.3 Result analysis: From the test data in Table 3, after high temperature treatment at 600°C, the macrostructure of sample S2' remained intact, and no cracks were observed. The compression stress retention rate at 50% strain was 92.3%. In contrast, visible microcracks appeared on the surface of sample D1', and the compression stress value decreased significantly, with a retention rate of only 34.3%. This data shows that S2' maintains most of its mechanical properties after high temperature treatment, while the mechanical properties of D1' have deteriorated severely.

[0070] The performance difference is due to the different internal interface structures of the two composite materials. For sample S2, the preparation method promotes the formation of Si-O-Si chemical bonding between the polysilazane fibers and the silica aerogel matrix. This chemical bonding interface can effectively transfer the interfacial stress generated by the mismatch of thermal expansion coefficients between the fibers and the matrix under high temperature conditions, inhibiting the initiation of interfacial debonding and microcracks, thereby maintaining the structural stability and mechanical properties of the material.

[0071] For sample D1, the quartz fibers and the silica matrix only have physical contact between them, and the interfacial bonding force is weak. In a high temperature environment, thermal mismatch stress is easily concentrated at the physical contact interface and leads to interface separation. This interface damage serves as an initial defect, which expands in subsequent compression tests, eventually resulting in the destruction of the macrostructure of the material and the sharp decline in mechanical properties. Therefore, by constructing a chemical bonding interface, the structural and performance stability of the composite material in a high temperature environment is effectively improved.

Claims

1. An aerogel composite fiber material, characterized in that: Measured by weight percentage, the aerogel composite fiber material comprises: 15-50% polysilazane fiber; and a 50-85% silica aerogel matrix; The silica aerogel matrix wraps the polysilazane fibers, and the polysilazane fibers and the silica aerogel matrix are connected by chemical bonding; An inert passivation layer is provided at the interface between the polysilazane fiber and the silica aerogel matrix. The inert passivation layer is a product generated by the reaction of an acidic substance with the surface of the polysilazane fiber.

2. A method for preparing the aerogel composite fiber material according to claim 1, characterized in that: The following steps are involved: S1. In-situ catalytic gelation: immersing polysilazane fibers in a silicon source precursor sol, and utilizing the self-reaction of the polysilazane fibers to trigger a gelation reaction of the silicon source precursor sol to form an alcohol gel composite material; S2. Gas phase treatment: The alcohol gel composite material is placed in a closed reactor and, at a temperature of 65-85° C., a carrier gas containing dimethyldichlorosilane at a volume concentration of 8-18 vol% is introduced to perform a gas phase pinning enhancement treatment. Then, the introduction of the dimethyldichlorosilane carrier gas is stopped and the closed reaction is maintained for 45-90 minutes to perform by-product-driven interface self-passivation. S3, normal pressure drying: heating and drying the composite material after the treatment in step S2 under normal pressure.

3. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: In step S1, after the alcogel composite material is formed, the method further includes aging the alcogel composite material in a constant temperature environment of 25-45° C. for 18-30 hours.

4. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: In step S1, the silicon source precursor sol is prepared from ethyl orthosilicate, anhydrous ethanol and deionized water in a molar ratio of 1:(15-35):(5-8).

5. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: In step S2, the duration of the vapor phase pinning enhancement treatment is 1.5-3.5 hours.

6. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: In step S2, the carrier gas is nitrogen.

7. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: The polysilazane fiber is prepared by the following method: Dichloromethylsilane is reacted with ammonia to obtain a liquid polysilazane precursor, the liquid polysilazane precursor is melt-spun, and cross-linked and cured under conditions of a temperature of 150-220° C. and a relative humidity of 70%-90% to obtain polysilazane fibers.

8. The method for preparing an aerogel composite fiber material according to claim 2, characterized in that: In step S3, the specific procedure of the atmospheric pressure drying is: heating to 70°C at a rate of 1°C / min and keeping the temperature constant for 2-4 hours, then heating to 110-150°C at a rate of 1°C / min and keeping the temperature constant for 4-6 hours.

9. Application of the aerogel composite fiber material according to claim 1 in the fields of aerospace, building insulation, industrial pipeline insulation and new energy.

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