High-temperature-resistant and good-elasticity ceramic fiber aerogel composite material and preparation method thereof

Abstract

The invention relates to the field of preparation of ceramic composite materials, and particularly discloses a high-temperature-resistant and good-elasticity ceramic fiber aerogel composite material and a preparation method thereof.The preparation method comprises the following steps that S1, ceramic nanofibers are prepared, specifically, an aluminum source compound and glacial acetic acid are added into absolute ethyl alcohol to obtain an aluminum source mixed solution, and the aluminum source mixed solution is stirred to be uniform; the preparation method comprises the following steps: adding an aluminum source mixed solution into a composite solution containing a silicon source compound, a catalyst and water, adding a spinning aid, stirring for 5-10 hours to obtain a precursor solution, carrying out electrostatic spinning to obtain precursor nanofibers, and calcining to obtain ceramic nanofibers; s2, preparation of the composite material: dipping the ceramic nanofibers into the modification liquid, adding a composite binder into the modification liquid, stirring and dispersing, taking out the ceramic nanofibers after the ceramic nanofibers stay for 30-50 minutes, stacking the ceramic nanofibers layer by layer to form a layered three-dimensional structural body, freezing the layered three-dimensional structural body with liquid nitrogen for 5-10 minutes for forming, freeze-drying the layered three-dimensional structural body for 20-30 hours, and annealing the layered three-dimensional structural body in an inert atmosphere to obtain the composite material. The ceramic fiber aerogel composite material provided by the invention is high in structural high-temperature stability and has excellent mechanical properties and heat-insulating properties.

Description

Technical Field

[0001] This invention relates to the field of ceramic composite material preparation, and specifically discloses a high-temperature resistant and elastic ceramic fiber aerogel composite material and its preparation method. Background Technology

[0002] Aerogels are advanced nanomaterials with a three-dimensional network structure. Their spatial network structure is filled with air, offering advantages such as high porosity, low density, and low thermal conductivity, resulting in excellent thermal insulation performance. Ceramic fiber materials, on the other hand, possess advantages such as good continuity and excellent mechanical properties. Therefore, combining aerogels and ceramic fiber materials, with ceramic fiber materials as a reinforcing phase incorporated into the aerogel, to obtain novel composite materials with even better mechanical and thermal properties is currently a hot research topic in thermal insulation materials. Based on elemental composition, existing ceramic aerogel composites can be classified into mono-, binary, ternary, and multi-element ceramic aerogels. Different types and quantities of elements contribute to the superior performance of ceramic aerogel composites.

[0003] Patent application number 202311144000.4 discloses a method for preparing a silica ceramic fiber aerogel heat insulation film, including the following steps: First, a spinning solution is prepared using a sol-gel method. A zirconium source is dissolved in water, and a phase inhibitor is added to form solution A; a silicon source is dissolved in water to form solution B; solutions A and B are mixed, a polymer template is added, and the mixture is homogeneous to obtain the spinning solution; Second, a precursor membrane is prepared by electrospinning; Third, the precursor membrane is calcined; Fourth, the fiber membrane is hydrophobically modified. The heat insulation film disclosed in this invention is a zirconium oxide-silica ceramic fiber membrane. In the silica-doped zirconium oxide fibers, zirconium oxide mainly exists in a tetragonal crystal form; and through airflow-assisted electrospinning, the fiber has good flexibility and continuity. In the heat insulation film of this invention, silicon, zirconium, and yttrium are uniformly distributed in the fibers, resulting in a uniform texture and good overall performance of the heat insulation film. However, due to the unstable interfacial bonding between the fiber and the aerogel, the composite material is prone to powder shedding simply by hydrophobically modifying the obtained fiber membrane. In addition, there is still room for improvement in its mechanical properties.

[0004] In view of this, the present invention discloses a ceramic fiber aerogel composite material with good high temperature resistance and elasticity, which is of particular importance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a high-temperature resistant and elastic ceramic fiber aerogel composite material and its preparation method. The ceramic fiber aerogel composite material provided by this invention exhibits high overall structural stability at high temperatures and possesses both excellent mechanical and thermal insulation properties.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, the method comprising the following steps: Preparation of S1-ceramic nanofibers: Aluminum source compound and glacial acetic acid are added to anhydrous ethanol to obtain aluminum source mixture. The aluminum source mixture is added to a composite solution containing silicon source compound, catalyst and water. Then, spinning aid is added and stirred for 5-10 hours to obtain precursor solution. Electrospinning is performed to obtain precursor nanofibers, which are then calcined to obtain ceramic nanofibers. Preparation of S2-composite material: Ceramic nanofibers are impregnated in a modified liquid, then a composite binder is added and stirred to disperse the mixture. After the ceramic nanofibers remain for 30-50 minutes, they are taken out and stacked layer by layer to form a layered three-dimensional structure. The structure is then frozen in liquid nitrogen for 5-10 minutes, freeze-dried for 20-30 hours, and finally annealed in an inert atmosphere to obtain the composite material.

[0007] Preferably, the electrospinning process parameters are as follows: the inner diameter of the injection needle is 0.7 mm, the spinning rate is 1.5~2 mL / h, the spinning distance is 0.30~0.40 m, the DC power supply voltage is 25~30 kV, the temperature is 20~30℃, and the humidity is 45~50%.

[0008] More preferably, the electrospinning process parameters are: injection needle inner diameter of 0.7 mm, spinning rate of 1.7 mL / h, spinning distance of 0.35 m, DC power supply voltage of 28 kV, temperature of 25 °C, and humidity of 48%.

[0009] Preferably, the calcination process parameters are as follows: gradually increase the temperature to 700~900℃ at a heating rate of 2-5℃ / min, and hold for 1~2 hours.

[0010] More preferably, the calcination process parameters are: gradually increasing the temperature to 800℃ at a heating rate of 4℃ / min, and holding at that temperature for 1.5h.

[0011] Preferably, the annealing process parameters are: gradually increasing the temperature to 700~900℃ at a heating rate of 2-5℃ / min, and holding at that temperature for 0.5~1h.

[0012] More preferably, the annealing process parameters are: gradually increasing the temperature to 800℃ at a heating rate of 3.5℃ / min, and holding at that temperature for 0.7h.

[0013] In some embodiments of the present invention, in step S1, the silicon source compound is tetraethyl orthosilicate and the aluminum source compound is isopropyl alumina, with a mass ratio of (1~4):1; more preferably 2.5:1.

[0014] In some embodiments of the present invention, in step S1, the ratio of the aluminum source compound, glacial acetic acid and anhydrous ethanol is 1g:(0.5-1)mL:(1-1.1)mL.

[0015] Preferably, in step S1, the total mass percentage of the silicon source compound and the aluminum source compound in the precursor solution is 10~40wt%.

[0016] More preferably, in step S1, the total mass percentage of the silicon source compound and the aluminum source compound in the precursor solution is 25 wt%.

[0017] Preferably, in step S1, the catalyst is anhydrous oxalic acid, and the amount added is 1 to 2% of the molar amount of the silicon source compound.

[0018] More preferably, in step S1, the amount of anhydrous oxalic acid added is 1.5% of the molar amount of the silicon source compound.

[0019] In some embodiments of the present invention, in step S1, the spinning aid is at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyethylene oxide, and its mass percentage in the precursor solution is 5 to 20 wt%.

[0020] Preferably, in step S1, the spinning aid is polyethylene oxide, and its mass percentage in the precursor solution is 12.5 wt%.

[0021] In some embodiments of the present invention, in step S2, the modified liquid is an aqueous suspension of carbon nanofibers.

[0022] Preferably, the diameter of the carbon nanofiber is 100~150nm.

[0023] In some embodiments of the present invention, in step S2, the mass ratio of the ceramic nanofibers and carbon nanofibers in the aqueous suspension is (1~2.3):1.

[0024] Preferably, in step S2, the mass ratio of carbon nanofibers in the aqueous suspension of ceramic nanofibers and carbon nanofibers is 1.7:1.

[0025] In some embodiments of the present invention, in step S2, the composite binder is a mixture of aluminum dihydrogen phosphate and a modified silicone binder.

[0026] Preferably, in step S2, the mass ratio of the ceramic nanofibers to the composite binder is (3~6):1.

[0027] More preferably, in step S2, the mass ratio of the ceramic nanofibers to the composite binder is 4.5:1.

[0028] Preferably, the composite binder is aluminum dihydrogen phosphate and modified silicone binder in a mass ratio of 1:(0.2~1).

[0029] More preferably, the composite binder is aluminum dihydrogen phosphate and modified silicone binder in a mass ratio of 1:0.6.

[0030] In some embodiments of the present invention, the preparation steps of the modified silicone binder are as follows: (1) Toluene, hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane, silicon nitride and dimethyl silicone oil are added sequentially to the reactor and stirred for 10-30 min. Then, under a vacuum of 0.04-0.08 MPa, the mixture is stirred for 20-30 min. Then, organosilicon crosslinking agent and catalyst 2 are added and stirred for 10-20 min to obtain a mixture. (2) Add polyacrylamide and deionized water to the reactor and stir for 2-6 hours. Add the mixture obtained in step (1) and stir for 1-2 hours to obtain the modified silicone binder.

[0031] Preferably, the viscosity of the hydroxyl-terminated polydimethylsiloxane is 1000~2000 centistokes at 25°C.

[0032] More preferably, the viscosity of the hydroxyl-terminated polydimethylsiloxane is 1500 centistokes at 25°C.

[0033] In some embodiments of the present invention, in step (1), the mass ratio of the terminal hydroxyl polydimethylsiloxane, methyltrimethoxysilane and silicon nitride is 10:(0.2~0.5):(2~8).

[0034] Preferably, in step (1), the mass ratio of the terminal hydroxyl polydimethylsiloxane, methyltrimethoxysilane and silicon nitride is 10:0.35:5.

[0035] Preferably, in step (1), the amount of toluene added is 10-20% of the total mass of hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane and silicon nitride.

[0036] Preferably, in step (1), the amount of dimethyl silicone oil added is 4 to 5% of the mass of the hydroxyl-terminated polydimethylsiloxane.

[0037] Preferably, in step (1), the organosilicon crosslinking agent is tetraethyl orthosilicate, and the amount added is 10-12% of the mass of hydroxyl-terminated polydimethylsiloxane.

[0038] Preferably, in step (1), the catalyst 2 is a titanate catalyst, and the amount added is 0.05~5% of the mass of the terminal hydroxyl polydimethylsiloxane.

[0039] Preferably, the titanate catalyst is tetraisopropyl titanate.

[0040] In some embodiments of the present invention, in step (2), the amount of polyacrylamide added is 1 to 2 times the mass of the mixture.

[0041] Preferably, in step (2), the amount of deionized water added is 1 to 5 times the total mass of polyacrylamide and the mixture.

[0042] The ceramic fiber aerogel prepared in this application uses a composite binder containing a modified silicone binder to connect ceramic fibers. Compared with the inorganic binders commonly used in the prior art, such as aluminum dihydrogen phosphate, which often require a higher concentration to achieve tight bonding between structures, the modified silicone binder prepared in this application introduces a specific amount of methyltrimethoxysilane and silicon nitride. Through the interaction between the components, under the steric hindrance effect of polyacrylamide, not only is the sedimentation and agglomeration of the system avoided, but it can also be uniformly and firmly attached to the contact surface. Under the specific ratio of aluminum dihydrogen phosphate and modified silicone binder, the composite material still has high stability and mechanical strength at high temperatures.

[0043] Meanwhile, although the synergistic effect of the modified silicone binder and aluminum dihydrogen phosphate effectively increases its bonding strength at high temperatures, the modified silicone binder's thermal conductivity affects the composite material preparation process, thus negatively impacting the final thermal conductivity and insulation performance of the composite material. To address this, the present invention introduces a carbon fiber network structure, constructing complex heat conduction paths to repair and even further enhance the composite material's insulation performance. The applicant unexpectedly discovered that the introduction of this carbon fiber network structure creates a physical entanglement with the ceramic nanofibers, further improving the mechanical properties of the composite material. Furthermore, it synergistically enhances the structural stability of the composite material with the composite binder, further reducing the amount of composite binder required and improving the service stability of the composite material.

[0044] In another aspect, the present invention provides a ceramic fiber aerogel composite material with good high temperature resistance and elasticity obtained by the above preparation method. The ceramic fiber aerogel composite material has at least the following properties: plastic deformation ≤14.5% under 1000 cycles of compression at 60% strain, volume loss rate ≤18.4% after calcination at 1300℃ for 1h, and thermal conductivity of 0.025~0.043W / (mK).

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The ceramic fiber aerogel composite material provided by the present invention is prepared by using a modified silicone binder in combination with a specific inorganic binder, and further modified by introducing a carbon fiber network structure. The resulting composite material has high high temperature stability and excellent mechanical and thermal insulation properties.

[0046] (2) The ceramic fiber aerogel prepared in this application is connected to the ceramic fiber by a composite binder containing modified silicon binder. Through the interaction between the components, not only is the sedimentation and agglomeration of the system avoided, but it can also be uniformly and firmly attached to the surface of ceramic nanofibers and aerogel. Under a specific ratio of aluminum dihydrogen phosphate and modified silicon binder, the composite material still has high stability and mechanical strength at high temperature.

[0047] (3) The present invention introduces a carbon fiber network structure, which repairs or even further improves the thermal insulation performance of the composite material by constructing a complex heat conduction path; at the same time, the introduction of the carbon fiber network structure and the physical entanglement between the ceramic nanofibers further improve the mechanical properties of the composite material, and it plays a synergistic role with the composite binder in stabilizing the composite material structure, further reducing the amount of composite binder added, and also improving the service stability of the composite material. Detailed Implementation

[0048] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0049] Unless otherwise specified, all reagents used below are readily available from commercial companies. Among them, carbon nanofibers (120 nm in diameter) were purchased from Beijing Beike New Material Technology Co., Ltd.; polyethylene oxide was purchased from Jiangsu Bosite Chemical Technology Co., Ltd.; polyacrylamide was purchased from Henan Fangao Environmental Protection Materials Co., Ltd.; and hydroxyl-terminated polydimethylsiloxane (viscosity 1500 centistokes, 25°C) was purchased from Jinan Xinglongda Chemical Co., Ltd.

[0050] Unless otherwise specified, the post-processing steps such as "liquid nitrogen freezing", "freeze drying", and "layer stacking" used below are routine operations for those skilled in the art, and should be selected according to actual operations.

[0051] Preparation Example 1 The preparation steps of the modified silicone binder are as follows: (1) Add 12 mL toluene, 50 g hydroxyl-terminated polydimethylsiloxane, 1.75 g methyltrimethoxysilane, 25 g silicon nitride and 2.25 g dimethyl silicone oil to the reactor in sequence, stir for 20 min, stir for 25 min under vacuum of 0.06 MPa, add 5.5 g tetraethyl orthosilicate and 1 g tetraisopropyl titanate, stir for 15 min to obtain a mixture; (2) Add 15g of polyacrylamide and 75mL of deionized water to the reactor, stir for 4h, add 10g of the mixture obtained in step (1), stir for 1.5h, and the modified silicone binder is obtained.

[0052] Preparation Example 2 The preparation steps of the modified silicone binder are the same as those in Preparation Example 1, except that the amount of methyltrimethoxysilane added in step (1) is 0.7g.

[0053] Preparation Example 3 The preparation steps of the modified silicone adhesive are the same as those in Preparation Example 1, except that the amount of polyacrylamide added in step (2) is 5g.

[0054] Example 1 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, the method comprising the following steps: Preparation of S1-ceramic nanofibers: 7.14 g of isopropyl alumina and 5.7 mL of glacial acetic acid were added to 7.5 mL of anhydrous ethanol to obtain an aluminum source mixture. The entire aluminum source mixture was added to a composite solution containing 17.86 g of tetraethyl orthosilicate, 0.12 g of anhydrous oxalic acid and 100 mL of water and stirred until homogeneous. Then, 12.5 g of polyethylene oxide was added and stirred for 7.5 h to obtain a precursor solution. Electrospinning was performed to obtain precursor nanofibers, which were then calcined to obtain ceramic nanofibers. The electrospinning process parameters are as follows: injection needle inner diameter 0.7 mm, spinning rate 1.7 mL / h, spinning distance 0.35 m, DC power supply voltage 28 kV, temperature 25℃, humidity 48%; The calcination process parameters are as follows: gradually increase the temperature to 800℃ at a heating rate of 4℃ / min, and hold for 1.5h; Preparation of S2-composite material: 17g of ceramic nanofibers were impregnated in 500mL of an aqueous suspension containing 10g of carbon nanofibers, followed by the addition of 2.4g of aluminum dihydrogen phosphate and 1.4g of modified silicon binder. The mixture was stirred and dispersed. After the ceramic nanofibers had been held for 40min, they were removed and stacked layer by layer to form a layered three-dimensional structure. The structure was then frozen in liquid nitrogen for 8min to form the composite material, freeze-dried for 25h, and finally annealed in a nitrogen atmosphere to obtain the composite material. The annealing process parameters are as follows: gradually increase the temperature to 800℃ at a heating rate of 3.5℃ / min, and hold for 0.7h; The modified silicone binder used was prepared in Preparation Example 1.

[0055] Example 2 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, the method comprising the following steps: Preparation of S1-ceramic nanofibers: 2.86g of isopropyl alumina and 2.3mL of glacial acetic acid were added to 3mL of anhydrous ethanol to obtain an aluminum source mixture. The entire aluminum source mixture was added to a composite solution containing 7.14g of tetraethyl orthosilicate, 0.03g of anhydrous oxalic acid and 100mL of water and stirred until homogeneous. Then, 5g of polyethylene oxide was added and stirred for 5h to obtain a precursor solution. Electrospinning was performed to obtain precursor nanofibers, which were then calcined to obtain ceramic nanofibers. The electrospinning process parameters are the same as in Example 1; The calcination process parameters are the same as in Example 1; Preparation of S2-composite material: 17g of ceramic nanofibers were impregnated in 500mL of aqueous suspension containing 7.4g of carbon nanofibers, followed by the addition of 3.5g of aluminum dihydrogen phosphate and 2.1g of modified silicon binder. The mixture was stirred and dispersed. After the ceramic nanofibers had been held for 30min, they were removed and stacked layer by layer to form a layered three-dimensional structure. The structure was then frozen in liquid nitrogen for 10min to form the composite material, freeze-dried for 30h, and annealed in a nitrogen atmosphere to obtain the composite material. The annealing process parameters are the same as in Example 1; The modified silicone binder used was prepared in Preparation Example 1.

[0056] Example 3 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, the method comprising the following steps: Preparation of S1-ceramic nanofibers: 11.43g of isopropyl alumina and 9mL of glacial acetic acid were added to 12mL of anhydrous ethanol to obtain an aluminum source mixture. The entire aluminum source mixture was added to a composite solution containing 28.57g of tetraethyl orthosilicate, 0.25g of anhydrous oxalic acid and 100mL of water and stirred until homogeneous. Then, 20g of polyethylene oxide was added and stirred for 10h to obtain a precursor solution. Electrospinning was performed to obtain precursor nanofibers, which were then calcined to obtain ceramic nanofibers. The electrospinning process parameters are the same as in Example 1; The calcination process parameters are the same as in Example 1; Preparation of S2-composite material: 17g of ceramic nanofibers were impregnated in 500mL of aqueous suspension containing 17g of carbon nanofibers, followed by the addition of 0.8g of aluminum dihydrogen phosphate and 0.5g of modified silicon binder. The mixture was stirred and dispersed. After the ceramic nanofibers had been held for 50min, they were removed and stacked layer by layer to form a layered three-dimensional structure. The structure was then frozen in liquid nitrogen for 8min to form the composite material, freeze-dried for 20h, and finally annealed in a nitrogen atmosphere to obtain the composite material. The annealing process parameters are the same as in Example 1; The modified silicone binder used was prepared in Preparation Example 1.

[0057] Example 4 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that the modified silicone binder used is prepared in Example 2.

[0058] Example 5 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that the modified silicone binder used is prepared in Example 3.

[0059] Comparative Example 1 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that silica sol (40% effective component, purchased from Jinan Mingrun Chemical Co., Ltd.) is added in equal amounts to replace aluminum dihydrogen phosphate and modified silica binder.

[0060] Comparative Example 2 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that a modified silicone binder is added in equal amounts to replace aluminum dihydrogen phosphate and the modified silicone binder.

[0061] Comparative Example 3 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that aluminum dihydrogen phosphate is added in equal amounts to replace aluminum dihydrogen phosphate and modified silicone binder.

[0062] Example 6 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that 8g of ceramic nanofibers are immersed in 500mL of an aqueous suspension containing 10g of carbon nanofibers.

[0063] Example 7 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that 25g of ceramic nanofibers are immersed in 500mL of an aqueous suspension containing 10g of carbon nanofibers.

[0064] Comparative Example 4 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, the method comprising the following steps: The preparation of S1-ceramic nanofibers is the same as in Example 1; The electrospinning process parameters are the same as in Example 1; The calcination process parameters are the same as in Example 1; Preparation of S2-composite material: 17g of ceramic nanofibers were impregnated in 500mL of an aqueous solution containing 2.4g of aluminum dihydrogen phosphate and 1.4g of modified silicone binder, and stirred and dispersed. After the ceramic nanofibers were left to stand for 40min, they were taken out and stacked layer by layer to form a layered three-dimensional structure. The structure was frozen in liquid nitrogen for 8min, then freeze-dried for 25h, and then annealed in a nitrogen atmosphere to obtain the composite material. The annealing process parameters are the same as in Example 1; The modified silicone binder used was prepared in Preparation Example 1.

[0065] Example 8 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that 3.5g of aluminum dihydrogen phosphate and 0.3g of modified silicone binder are added.

[0066] Example 9 A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material is described. The specific preparation method is the same as in Example 1, except that 1.8g of aluminum dihydrogen phosphate and 2.0g of modified silicone binder are added.

[0067] Performance testing: The ceramic fiber aerogel composite materials prepared in the above embodiments and comparative examples were subjected to the following performance tests, and the specific test results are shown in Table 1: (1) Compression performance: The compression performance of each ceramic fiber aerogel composite material was tested using a TA-Q850 dynamic mechanical analyzer (DMA, TA Corporation, USA). 1000 cycles of compression test with a strain of 60% were performed to characterize the compressive elasticity of the ceramic fiber aerogel composite material. The smaller the plastic deformation, the better the compressive elasticity. The test size was 10mm×10mm×5mm.

[0068] (2) Temperature resistance: Each ceramic fiber aerogel composite material was calcined at 1300℃ for 1h. The size change before and after calcination was recorded and the volume loss rate was calculated to characterize the temperature resistance of each ceramic fiber aerogel composite material. The smaller the volume loss rate, the better the temperature resistance. The test size was 4cm×4cm in length and width and 1.3cm±0.2cm in thickness.

[0069] (3) Thermal insulation performance: Using a TPS2500S thermal conductivity meter (HotDisk, HotDisk, Switzerland), the transient planar heat source method was adopted to test the thermal conductivity of ceramic fiber aerogel composites according to ISO22007-2:2015 standard to characterize the thermal insulation performance of each ceramic fiber aerogel composite. The smaller the thermal conductivity, the better the thermal insulation performance. The test size was 4cm×4cm in length and width, and the thickness was 1.3cm±0.2cm.

[0070] Table 1

[0071] As shown in Table 1, the ceramic fiber aerogel composite materials provided in Examples 1-3 of the present invention have good compressive elasticity, low volume loss rate after high-temperature calcination at 1300℃, and excellent temperature resistance and thermal insulation performance. Examples 4 and 5 altered the preparation conditions of the modified silicone binder, both of which adversely affected the bonding between the building blocks of the composite material. During the high-temperature annealing process, powder shedding was very likely to occur, and the structural stability decreased, resulting in varying degrees of decline in the compressive properties, temperature resistance, and thermal insulation properties of the ceramic fiber aerogel composite material. In Comparative Example 1, replacing the composite binder with an equal amount of commercially available silicone binder had a small impact on the compressive properties of the ceramic fiber aerogel composite material, but its temperature resistance and thermal insulation properties decreased due to the influence of the silicone binder on the thermal conductivity of the system. Comparative Example 2, which only added modified silicone binder, showed less impact on compressive properties compared to Comparative Example 1. Comparative Example 3, which only added aluminum dihydrogen phosphate as a binder, showed the performance advantages of inorganic binders. The thermal insulation performance of the ceramic fiber aerogel composite material was almost unaffected, but the compressive performance still decreased, indicating that the bonding strength brought by using aluminum dihydrogen phosphate alone could not meet the requirements of this system. Examples 6 and 7 altered the ratio of ceramic nanofibers to carbon nanofibers, resulting in insufficient rigid support within the ceramic nanofibers. Consequently, the structural stability could not be maintained during annealing, ultimately leading to varying degrees of decline in compressive properties, temperature resistance, and thermal insulation properties. In Comparative Example 4, the ceramic nanofibers were not impregnated with an aqueous suspension of carbon nanofibers. The thermal insulation performance of the ceramic fiber aerogel composite material decreased significantly. This may be because the influence of the composite binder on the thermal insulation performance of the ceramic fiber aerogel composite material was not effectively compensated. The compressive performance also decreased. This also indicates that there is a physical entanglement between the fiber network structure formed by the carbon nanofibers in the composite material and the ceramic nanofibers, which helps to improve the mechanical properties of the composite material. Examples 8 and 9 changed the composite ratio of aluminum dihydrogen phosphate and modified silicone binder in the composite binder, demonstrating that the specific ratio of aluminum dihydrogen phosphate and modified silicone binder of the present invention can achieve a balance between the compressibility, temperature resistance and thermal insulation properties of the ceramic fiber aerogel composite material.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material, characterized in that, The preparation method includes the following steps: Preparation of S1-ceramic nanofibers: Aluminum source compound and glacial acetic acid are added to anhydrous ethanol to obtain aluminum source mixture. The aluminum source mixture is added to a composite solution containing silicon source compound, catalyst and water. Then, spinning aid is added and stirred for 5-10 hours to obtain precursor solution. Electrospinning is performed to obtain precursor nanofibers, which are then calcined to obtain ceramic nanofibers. Preparation of S2-composite material: Ceramic nanofibers are impregnated in a modified liquid, then a composite binder is added and stirred to disperse the mixture. After the ceramic nanofibers remain for 30-50 minutes, they are taken out and stacked layer by layer to form a layered three-dimensional structure. The structure is then frozen in liquid nitrogen for 5-10 minutes, freeze-dried for 20-30 hours, and finally annealed in an inert atmosphere to obtain the composite material.

2. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 1, characterized in that, In step S1, the silicon source compound is tetraethyl orthosilicate and the aluminum source compound is isopropyl alumina, with a mass ratio of (1~4):

1.

3. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 1, characterized in that, In step S1, the spinning aid is at least one of polyvinyl alcohol, polyvinylpyrrolidone and polyethylene oxide, and its mass percentage in the precursor solution is 5-20 wt%.

4. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 1, characterized in that, In step S2, the modified liquid is an aqueous suspension of carbon nanofibers.

5. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 4, characterized in that, In step S2, the mass ratio of carbon nanofibers in the aqueous suspension of ceramic nanofibers and carbon nanofibers is (1~2.3):

1.

6. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 1, characterized in that, In step S2, the composite adhesive is a mixture of aluminum dihydrogen phosphate and modified silicone adhesive.

7. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 6, characterized in that, The preparation steps of the modified silicone binder are as follows: (1) Toluene, hydroxyl-terminated polydimethylsiloxane, methyltrimethoxysilane, silicon nitride and dimethyl silicone oil are added sequentially to the reactor and stirred for 10-30 min. Then, under a vacuum of 0.04-0.08 MPa, the mixture is stirred for 20-30 min. Then, organosilicon crosslinking agent and catalyst 2 are added and stirred for 10-20 min to obtain a mixture. (2) Add polyacrylamide and deionized water to the reactor and stir for 2-6 hours. Add the mixture obtained in step (1) and stir for 1-2 hours to obtain the modified silicone binder.

8. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 7, characterized in that, In step (1), the mass ratio of the terminal hydroxyl polydimethylsiloxane, methyltrimethoxysilane and silicon nitride is 10:(0.2~0.5):(2~8).

9. The method for preparing a high-temperature resistant and elastic ceramic fiber aerogel composite material according to claim 7, characterized in that, In step (2), the amount of polyacrylamide added is 1 to 2 times the mass of the mixture.

10. A ceramic fiber aerogel composite material with good high-temperature resistance and elasticity as described in any one of claims 1-9, characterized in that, The ceramic fiber aerogel composite material shall have at least the following properties: plastic deformation ≤14.5% under 1000 cycles of compression at 60% strain, volume loss ≤18.4% after calcination at 1300℃ for 1h, and thermal conductivity of 0.025~0.043W / (mK).

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