Preparation method of wave-transparent high-temperature radiation-resistant heat insulation material

Abstract

The application relates to a preparation method of a wave-transparent high-temperature radiation-resistant heat insulation material, which comprises the following steps: preparing alumina nanowire clusters with a certain length-diameter ratio by a hydrothermal method; uniformly mixing a certain proportion of wave-transparent radiation-resistant agents by using a kneader, and molding the alumina nanowire clusters containing the wave-transparent radiation-resistant agents; placing the molded blocks in a silane-based precursor solution containing a catalyst; then performing an aging process; performing a gradient solvent replacement; then performing a subcritical drying process and a heat treatment process in an inert atmosphere. The alumina nanowires with a high length-diameter ratio are used for three-dimensional lapping, and the silane-based precursor is used for modification, so that the preparation of low-cost, wave-transparent, light and high-efficiency heat insulation aerogels is realized. At high temperature, the radiation-resistant agents in the aerogels can effectively resist infrared radiation, and the high-temperature thermal conductivity of the aerogels is greatly reduced. The application designs the doping of the wave-transparent radiation-resistant agents, so that the nanometer aerogels have the characteristics of low cost, wave transparency, low thermal conductivity and the like.

Description

Technical Field

[0001] This invention relates to the field of aerogel preparation technology, and in particular to a method for preparing a wave-transparent, high-temperature radiation-resistant heat insulation material. Background Technology

[0002] As aircraft develop towards higher, farther, and stronger capabilities, the demand for thermal insulation materials is increasing, especially for functional thermal insulation materials that combine wave transmission, light transmission, and stealth capabilities. In recent years, with the explosive growth in demand for radome thermal insulation, wave-transparent thermal insulation materials have become a research hotspot. However, existing wave-transparent thermal insulation materials have relatively high thermal conductivity and occupy a large amount of space under stringent thermal insulation requirements. Therefore, the development of aerogel thermal insulation materials that combine wave transmission, lightweight properties, and high-efficiency thermal insulation is urgently needed.

[0003] Aerogel materials are gel materials in which the dispersion medium is a gas. They are nanoporous solid materials with a network structure, composed of colloidal particles or polymer molecules aggregated together. The pore size in these materials is on the nanometer scale. Their porosity is as high as 80–99.8%, the typical pore size is 1–100 nm, and the specific surface area is 200–1000 m². 2 / g, while the density can be as low as 3kg / m³ 3 Aerogels have a thermal conductivity as low as 0.012 W / m·K at room temperature. These characteristics give aerogels broad application potential in thermal, acoustic, optical, microelectronic, and particle detection fields. Currently, the most widespread application of aerogels remains in thermal insulation, as their unique nanostructure effectively reduces convection and solid-phase conduction. Undoubtedly, aerogels are among the most efficient thermal insulation materials at low and medium temperatures. However, at high temperatures, infrared radiation is severe, and the thermal conductivity of some near-infrared transparent aerogels increases significantly at high temperatures. Therefore, for systems with high infrared transmittance, it is necessary to dope them with certain light-blocking agents to reduce thermal conductivity at high temperatures and improve the overall thermal insulation efficiency of the material. However, in actual preparation, conventional radiation-resistant agents often have high dielectric constants, making it impossible to simultaneously achieve infrared radiation resistance and wave transmission performance. Therefore, designing highly efficient, wave-transparent thermal insulation materials is a recognized technical challenge.

[0004] Chinese patent application CN201810068117.1 discloses a method for preparing a high-temperature resistant aerogel material. Although the aerogel prepared by this method has good high-temperature resistance, with a heat resistance temperature above 1000℃ and even able to withstand temperatures above 1300℃, the aerogel material will still undergo a series of phase transitions at temperatures above 1200℃, resulting in a small specific surface area after high-temperature heat treatment, not exceeding 100m². 2 / g, therefore the high-temperature thermal insulation performance of this aerogel material is not very good.

[0005] Chinese patent CN201910630467.7 discloses a method for preparing a high-temperature resistant irregularly shaped nanocrystalline aerogel material. This method uses nanorods and silica sol to assemble the material, which exhibits good temperature resistance, withstanding a temperature limit of 1400℃. However, the preparation process requires steps such as a sol-gel process, aging and solvent replacement, and supercritical drying, significantly increasing the complexity and extending the preparation cycle. Furthermore, the material's thermal conductivity at high temperatures is close to 0.1 W / m·K, requiring thicker insulation materials to meet practical needs, which is difficult to satisfy under weight reduction and space constraints.

[0006] From a cost perspective, the preparation of traditional aerogel materials mostly relies on supercritical drying equipment, which involves complex processes and high costs, thus limiting the mass production of certain products. Due to the high cost of supercritical drying, researchers are exploring other drying methods, such as atmospheric pressure drying and freeze-drying, for aerogel preparation. In ordinary atmospheric pressure drying, the aerogel skeleton is relatively weak, and under the influence of liquid surface tension, the skeleton collapses significantly, resulting in a substantial decrease in porosity and specific surface area, drastically reducing the material's bulk density and thermal insulation efficiency. Some researchers have focused on coarsening the skeleton and reducing surface energy, increasing its strength to resist liquid surface tension on the one hand, and modifying the skeleton hydrophobically on the other to reduce the surface energy generated by solvent molecule escape. However, these two approaches often result in a relatively robust aerogel skeleton with insufficient thermal insulation efficiency. Compared to atmospheric pressure drying, freeze-drying can better maintain the pore structure. This method utilizes low-temperature freezing and sublimation to preserve the pores occupied by ice crystals, while preventing the skeleton from collapsing. Researchers have constructed nanofiber aerogels by combining nanofibers with aluminoborosilicate sol using a freeze-drying method. These aerogels exhibit a temperature resistance of up to 1100℃, representing an improvement over traditional nanoaerogels and providing an important reference for the preparation of high-temperature resistant aerogel materials. However, the aerogel framework and pore size prepared by this method exceed the typical aerogel structural characteristics (1-100 nm). In particular, the pores of 10-20 μm lead to severe gas-phase heat conduction and convection, resulting in a decrease in overall thermal insulation performance compared to typical aerogel materials, thus limiting their engineering applications in aerospace and other fields.

[0007] With the development of technology, various fields have placed high demands on thermal insulation materials, requiring not only excellent temperature resistance and high-temperature insulation performance, but also a method that can simultaneously achieve high-temperature, high-efficiency thermal insulation, wave transmission, lightweight, and low-cost characteristics in the preparation of aerogel thermal insulation materials. Therefore, with strict limitations on cost and production time, there is a strong need to develop an effective method to prepare aerogel materials that combine low cost, wave transmission, lightweight, and high-efficiency thermal insulation. Summary of the Invention

[0008] In order to solve the technical problems existing in the prior art, the present invention provides a method for preparing a wave-transparent high-temperature radiation-resistant heat insulation material.

[0009] In a first aspect, the present invention provides a method for preparing a wave-transparent, high-temperature radiation-resistant heat-insulating material, the method comprising the following steps:

[0010] (1) Dissolve 1-30g of alumina nanopowder (particle size 5-50nm) in 10-200mL of water, add a mixture of 0.001-1mol / L hydrochloric acid and 0.001-1mol / L sulfuric acid (weight ratio 1:1) as an adsorbent and react at 100-300℃ for 1-7h to obtain alumina nanowire clusters with a diameter of 10-100nm and a length of 100-800μm.

[0011] (2) The alumina nanoclusters obtained in step (1) are mixed with a wave-transparent anti-radiation agent and dispersed uniformly using a kneader. The kneader is bidirectional and rotates at a speed of 10-100 r / min to obtain a wet gel, which accounts for 0.1-3% of the mass of the wet gel.

[0012] (3) Place the wet gel obtained in step (2) into a mold for pre-flattening and then molding. The molding is carried out in two steps. First, use a pressure of 0.1-2 MPa for 5-30 minutes to initially form the shape, and then use a pressure of 1-5 MPa for 1-20 minutes to fix the shape, thereby obtaining a wet gel block.

[0013] (4) Immerse the wet gel from (3) in a mixture of methyltrimethoxysilane, ethanol, ammonia (A) and ammonium fluoride (B) (the amount of the mixture is 2-5 times the volume of the block, and the mass ratio of solution A to solution B is 100:1-100:20). Set a stirring magnet at the bottom of the rack and stir at 100-300 r / min to promote solvent replacement and catalysis, thereby obtaining a composite gel. Let it stand for 6-24 h.

[0014] In step (4) above, the concentration of methyltrimethoxysilane in the mixture (A) is 0.5–20% by mass, the concentration of ammonia is 0.1–5% by mass, and the concentration of ammonium fluoride in the solution (B) is 0.05–0.5% by mass.

[0015] mol / L.

[0016] (5) Displace the composite gel obtained in step (4) in 5-15 times its volume of solvent, respectively, in ethanol solution, in a mixed solvent of ethanol and low surface energy solvent, and in pure low surface energy solvent for 3-5 days each. The low surface energy solvent can be, but is not limited to, petroleum ether, n-hexane, cyclohexane, etc.

[0017] (6) Place the composite gel obtained in step (5) in a specific container for subcritical drying. The container is a pressure-resistant, sealed structure made of metal, equipped with pressure control instruments, and has a vent. Seal the container with the wet gel block and place it in an oven at 40-80℃ for 1-12 hours. Then, open the vent valve for gas exchange for 5-30 minutes. Repeat the heating and venting steps 5-10 times. Afterward, remove the dried gel and place it at room temperature and pressure for 24-72 hours.

[0018] (7) The aerogel obtained in step (6) is subjected to a low-temperature heat treatment process to obtain a lightweight radiation-resistant aerogel.

[0019] (8) The prepared aerogel has a heat resistance temperature of 1100-1400℃, a dielectric constant of 1.1-1.4, a thermal conductivity of 0.028-0.038 W / m·K at room temperature, a thermal conductivity of 0.05-0.1 W / m·K at 1000℃, and a density of 0.1-0.3 g / cm³. 3 .

[0020] The present invention provides, in a second aspect, a method for preparing a wave-transparent, high-temperature radiation-resistant heat-insulating material as described in the first aspect of the present invention.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] (1) Unlike other doping modifications and other methods of preparing high-temperature resistant aerogel insulation materials, this invention uses long nanowires as the main unit for the assembly process. In typical examples, the nanowires prepared have a diameter as low as 20-50 nm and a length of 100-800 μm, which not only ensures a low thermal conductivity, but also improves the overall temperature resistance of the material due to the self-supporting effect of the three-dimensional network structure.

[0023] (2) Nanowire clusters with large aspect ratio can achieve a physically cross-linked wet gel network structure instead of cross-linking through chemical bonds. The wet gel can be repeatedly shaped, with strong process applicability and high utilization rate.

[0024] (3) By using a kneading method to combine viscous nanoclusters with radiation-resistant agent powder, the problem of radiation-resistant agent sedimentation in solution during the traditional radiation-resistant agent doping process is solved, thus effectively improving the heat insulation efficiency of the material.

[0025] (4) The present invention uses a wave-transparent radiation-resistant agent, which solves the contradiction between wave transmission and radiation resistance in traditional materials, so that the material has both high-efficiency heat insulation and wave transmission performance.

[0026] (5) This patent uses a silane precursor and a nanowire framework to construct a hierarchical micro-nano structure. The hydrophobic secondary structure formed by the nanoparticles effectively fills the pores between the nanowires. On the one hand, it improves the heat transfer path and reduces the gas phase heat conduction process, which effectively improves the heat insulation efficiency of the nano aerogel. On the other hand, the hydrophobic framework can reduce the interfacial tension in the drying process, which is beneficial to the subcritical drying process.

[0027] (6) Nanowires have the functions of self-supporting and self-toughening of the skeleton, eliminating the need for fiber reinforcement process in traditional aerogel composites. Their lightweight properties are improved by more than 50% compared with similar aerogel products.

[0028] (7) The self-supporting effect of the nanowire framework determines that it can be dried through a subcritical drying process, unlike atmospheric pressure drying and supercritical drying. It can maintain a slender framework while achieving the construction of a high-porosity framework. The subcritical drying process can effectively reduce costs and reduce dependence on large-scale equipment. Attached Figure Description

[0029] Figure 1 This is a flowchart of the preparation process of the present invention.

[0030] Figure 2 This is a physical image of the nanoaerogel prepared in Example 1.

[0031] Figure 3 This is a SEM image of the aerogel prepared in Example 1. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0033] In a first aspect, the present invention provides a method for preparing a wave-transparent, high-temperature radiation-resistant heat-insulating material, the method comprising the following steps:

[0034] The present invention will be further described below by way of examples, but the scope of protection of the present invention is not limited to these embodiments.

[0035] Example 1

[0036] (1) Dissolve 6g of alumina nanopowder (particle size of 20nm) in 100mL of water, add 0.02mol / L hydrochloric acid and sulfuric acid as adsorbents and react at 220℃ for 7h to obtain alumina nanowire clusters with a diameter of 50nm and a length of 100-800μm.

[0037] (2) The alumina nanowire clusters obtained in step (1) are mixed with chromium oxide nanoparticles accounting for 1% of the mass of the wet gel and dispersed uniformly using a kneader. The kneader is bidirectional and rotates at a speed of 20 r / min to obtain the wet gel.

[0038] (3) Place the wet gel obtained in step (2) into a mold for pre-flattening and then molding. The molding is carried out in two steps: first, use a pressure of 0.5 MPa for 30 minutes for preliminary molding, and then use a pressure of 2 MPa for 20 minutes for final shaping.

[0039] (4) Dissolve methyltrimethoxysilane in ethanol (2% by mass), add ammonia as a catalyst (0.1% by mass), and stir for 10 min to obtain solution A. Add 0.1 mol / L ammonium fluoride as a catalyst (solution B). Stir the above solution. The mass ratio of solution A to solution B is 100:1. Stir for 10 min to obtain mixed solution C. Impregnate the wet gel from (3) with solution C to carry out the gelation reaction. Set a stirring magnet at the bottom of the rack and stir at 100 r / min. Let stand for 12 h to promote solvent replacement and catalytic process, thereby obtaining composite gel.

[0040] (5) The composite gel obtained in step (4) was placed in 10 times the amount of solvent for replacement, and the solvents were ethanol solution, ethanol and cyclohexane mixed solvent, and cyclohexane for 3 days each.

[0041] (6) The composite gel obtained in step (5) is placed in a specific container for subcritical drying. The container is a pressure-resistant, sealed structure made of metal, equipped with pressure control instruments, and has a vent. The container with the wet gel block is sealed and placed in an oven at 50°C for 2 hours. Then, the vent valve is opened for gas exchange for 20 minutes. The heating and venting steps are repeated 6 times. The dried gel is then removed and placed at room temperature and pressure for 24 hours.

[0042] (7) The aerogel obtained in step (6) is subjected to a heat treatment process at 500℃ to obtain high temperature resistant alumina aerogel.

[0043] (8) The prepared aerogel has a heat resistance temperature of 1300℃, a room temperature thermal conductivity of 0.03 W / m·K, and a density of 0.15 g / cm³. 3 .

[0044] Example 2

[0045] Example 2 is basically the same as Example 1, except that the amount of alumina nanopowder in step 1 is 20g.

[0046] The thermal insulation performance of the alumina aerogel material in Example 2 was tested, and it was found that the surface of the aerogel material did not change color and did not fall off when touched lightly. Other performance indicators are shown in Table 1.

[0047] Comparative Example 1

[0048] Comparative Example 1 is basically the same as Example 1, except that the molding process in step 2 does not involve step-by-step molding.

[0049] The thermal insulation performance of the multi-component aerogel material in Comparative Example 1 was tested, and microcracks were found on the surface of the aerogel material. When touched lightly, the material would fall off in chunks. Other performance indicators are shown in Table 1.

[0050] Comparative Example 2

[0051] Comparative Example 2 is basically the same as Example 1, except that step 2 was not performed in the preparation process.

[0052] The thermal insulation performance of the multi-component aerogel material in Comparative Example 2 was tested, and it was found that the aerogel material shrank significantly during the drying process and deformed to a certain extent. Other performance indicators are shown in Table 1.

[0053] Comparative Example 3

[0054] Comparative Example 3 is basically the same as Example 1, except that step 4 does not involve multi-solvent replacement, but uses a single ethanol solvent replacement.

[0055] The thermal insulation performance of the multi-component aerogel material in Comparative Example 3 was tested, and it was found that the surface of the aerogel material had cracks and the overall shape was deformed compared with the wet gel. Other performance indicators are shown in Table 1.

[0056] Comparative Example 4

[0057] Comparative Example 4 is basically the same as Example 1, except that the drying process in step 5 is performed under normal pressure instead of a subcritical drying process.

[0058] Thermal insulation performance tests were conducted on the multi-component aerogel material in Comparative Example 4. It was found that the aerogel material had cracks on its surface and its overall shape was deformed compared to the wet gel. Other performance indicators are shown in Table 1.

[0059] Comparative Example 5

[0060] Comparative Example 5 is basically the same as Example 1, except that the prepared aerogel did not undergo the final heat treatment process.

[0061] In Comparative Example 5, the surface of the multi-component aerogel was smooth, with no cracking or peeling issues.

[0062] Comparative Example 6

[0063] Comparative Example 6 is basically the same as Example 1, except that the prepared aerogel did not undergo the anti-radiation agent kneading process in step 2.

[0064] In Comparative Example 6, the surface of the multi-component aerogel was smooth, with no cracking or peeling issues.

[0065] Comparative Example 7

[0066] Comparative Example 7 is basically the same as Example 1, except that carbon black and silicon carbide are used in the anti-radiation agent kneading process of the prepared aerogel in step 2.

[0067] In Comparative Example 7, the surface of the multi-component aerogel was smooth, with no cracking or peeling issues.

[0068] Comparative Example 8

[0069] Comparison 8 is basically the same as Example 1, except that in step 1, a 13nm diameter spherical nanocrystal solution is used instead of nanowire clusters for the forming process, and the subsequent steps are the same.

[0070] The results showed that the obtained material was a powder rather than an aerogel block.

[0071] Comparative Example 9

[0072] Comparative Example 9 is basically the same as Example 1, except that: no molding process is performed in step 2;

[0073] SEM testing revealed that the prepared material contained a large number of pores, causing defects.

[0074] Comparative Example 10

[0075] ① Sol preparation

[0076] Weigh 160g of methyl orthosilicate and 160g of acetonitrile into a 500mL beaker, seal it with plastic wrap, and stir magnetically for 1 min. After mixing evenly, add 60g of 0.003mol / L hydrochloric acid as a catalyst. This process should be done slowly, with magnetic stirring for 5 min. Add the above mixture to a 1000mL three-necked flask, heat and stir magnetically at 70℃, and reflux for 30 min to obtain the first solution of silica sol precursor. Add 160g of methyl orthosilicate to the first solution of silica sol precursor, and continue heating and stirring magnetically at 70℃ for 16 h to obtain silica sol (silica sol). Dilute the silica sol, evaporate 300g of the solvent contained in the silica sol, and then add 600g of acetonitrile and mix evenly to obtain the diluted silica sol. Refrigerate the diluted silica sol for later use.

[0077] ② Nanocrystal assembly process

[0078] 3.7g of alumina nanoparticles were dissolved in 34g of acetonitrile and stirred until homogeneous to obtain a first mixture. Then, 8g of the diluted silica sol was added to the first mixture as a binder and ultrasonically dispersed for 20min to obtain a second mixture. 2g of ammonia water with a concentration of 0.43mol / L was added to the second mixture and ultrasonically dispersed for another 20min to prepare an aerogel wet gel with oxide nanocrystals as the framework.

[0079] ③ Gelation and Aging

[0080] The prepared aerogel wet gel was placed in a mold and left to stand for 24 hours, and then placed in a 60℃ oven for 48 hours to complete the gelation and aging process.

[0081] ④ Solvent replacement

[0082] After the gelation and aging process was completed, the gel was removed and placed in 10 times its volume of ethanol for solvent replacement. The solvent replacement time was 3 days, and the solvent replacement process was repeated 3 times.

[0083] ⑤ Supercritical drying is used to obtain aerogel materials.

[0084] ⑥ Heat treatment process

[0085] The above-mentioned aerogel material was heated to 1200℃ (heat treatment temperature) in a furnace at a heating rate of 10℃ / min, held at that temperature for 1 hour (heat treatment time), and then cooled to room temperature in the furnace to obtain a high-temperature resistant aerogel material.

[0086] The performance indicators of the wave-transparent high-temperature radiation resistant aerogel materials in Examples 1-2 and the aerogel materials in Comparative Examples 1-11 are shown in Table 1.

[0087] Comparative Example 11: Designed according to Patent CN19100410

[0088] Table 1: Performance indicators of the alumina aerogel materials prepared in Examples 1-2 and the high-temperature resistant aerogel materials in Comparative Examples 1-11.

[0089]

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a wave-transparent high-temperature radiation resistant heat insulating material, characterized by, The method comprises the following steps: (1) using a mixture of hydrochloric acid and sulfuric acid as a catalyst, preparing alumina nanowire clusters with a diameter of 10-100 nm and a length of 100-800 μm through high-temperature hydrothermal reaction; (2) mixing the alumina nanowire clusters obtained in step (1) with a wave-transparent anti-radiation agent, homogeneously dispersing the mixture by using a kneader, rotating the kneader in two directions at a speed of 10-100 r / min, thereby obtaining a wet gel, wherein the wave-transparent anti-radiation agent accounts for 0.1-3% of the mass of the wet gel; (3) performing mold pressing on the wet gel obtained in step (2), which is divided into two steps, preliminarily forming the wet gel by using a pressure of 0.5 MPa for 30 min, and then shaping the wet gel by using a pressure of 2 MPa for 20 min, thereby obtaining a wet gel block; (4) immersing the wet gel in step (3) in a mixed solution of methyltrimethoxysilane, ethanol, ammonia water and a solution of ammonium fluoride, setting a stirring magnet in the lower part of a bracket, and stirring at a speed of 100-300 r / min to promote solvent replacement and catalysis, thereby obtaining a composite gel, and standing for 6-24 h; (5) placing the composite gel obtained in step (4) in a 5-15-fold ethanol solution, a mixed solution of ethanol and a low-surface-energy solvent, and a pure low-surface-energy solvent respectively for 3-5 days to replace the solvents; (6) placing the composite gel obtained in step (5) in a special container to perform a subcritical drying process, thereby obtaining an aerogel material; (7) performing a low-temperature heat treatment process on the aerogel material obtained in step (6), thereby obtaining a lightweight anti-radiation aerogel, i.e., a wave-transparent anti-high-temperature radiation heat insulation material.

2. The production method according to claim 1, characterized by, In step (1), 1-30 g of alumina nanopowder with a particle size of 5-50 nm is dissolved in 10-200 mL of water, 0.1-2 g of a mixture of 0.001-1 mol / L hydrochloric acid and 0.001-1 mol / L sulfuric acid with a weight ratio of 1:1 is added as an adsorbent, and the mixture is reacted at 100-300 ℃ for 1-7 h, thereby obtaining alumina nanowire clusters with a diameter of 10-100 nm and a length of 100-800 μm.

3. The preparation method according to claim 1, characterized in that, In step (2), the wave-transparent anti-radiation agent is chromium oxide or beryllium oxide.

4. The method of claim 1, wherein, In step (4), the amount of the mixed solution is 2-5 times the volume of the block.

5. The preparation method according to claim 1, characterized in that, The low-surface-energy solvent is petroleum ether, n-hexane or cyclohexane.

6. The method of claim 1, wherein, The special container in step (6) is made of metal and has a pressure-resistant closed structure, is provided with instruments and apparatus for regulating pressure, and is provided with a gas outlet.

7. The preparation method according to claim 1, characterized in that, In step (4), in the mixed solution A, the concentration of methyltrimethoxysilane is 0.5-20 mass%, and the concentration of ammonia is 0.1-5 mass%; in the solution B, the concentration of ammonium fluoride is 0.05-0.5 mol / L.

8. The preparation method according to claim 1, wherein in step (4), the mass ratio of the mixed solution A to the solution B is 100:1-100:

20.

9. A wave-transparent high-temperature radiation resistant heat insulating material, characterized by The wave-transparent high-temperature resistant radiation insulation material is prepared by the preparation method in any one of claims 1-8, has a heat-resistant temperature of 1100-1400 DEG C, a dielectric constant of 1.1-1.4, a room-temperature thermal conductivity of 0.028-0.038 W / m*K, a 1000 DEG C thermal conductivity of 0.05-0.1 W / m*K, and a density of 0.1-0.3 g / cm 3 .

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