A method for preparing high-temperature-resistant and high-strength aerogel material by normal pressure drying and high-temperature-resistant and high-strength aerogel material prepared by the method

Abstract

The application relates to a method for preparing high-temperature-resistant and high-strength aerogel materials through normal-pressure drying and high-temperature-resistant and high-strength aerogel materials prepared by the method. The method comprises the following steps: uniformly mixing aluminum oxide nano powder, aluminum silicate fiber, aluminum oxide fiber and hydrochloric acid with water to obtain a mixed solution, then placing the mixed solution in a hydrothermal reaction at 200-300 DEG C to obtain a gel; soaking the gel in water to obtain a soaking treatment gel; performing normal-pressure drying on the soaking treatment gel to obtain an aerogel material; and performing heat treatment on the aerogel material in an air atmosphere to obtain the high-temperature-resistant and high-strength aerogel material. The high-temperature-resistant and high-strength aerogel material prepared by the application is a cage-shaped nano structure surrounded by nanometer belts, has better mechanical strength, does not need a supercritical drying process, and can directly obtain the high-temperature-resistant and high-strength aerogel material with good temperature resistance, high strength, high efficiency, low density and excellent high-temperature heat insulation performance through normal-pressure drying and a relatively low-temperature heat treatment step.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aerogel preparation, and particularly relates to a method for preparing high-temperature-resistant and high-strength aerogel material through normal-pressure drying and high-temperature-resistant and high-strength aerogel material prepared by the method. BACKGROUND

[0002] Nanoporous aerogel (aerogel for short) material is a gel material with gas as a dispersion medium, and is a kind of nanoporous solid material with network structure formed by mutual accumulation of colloidal particles or polymer molecules. The size of the pores in the material is in the order of nanometers. The porosity of the material can be as high as 80-99.8%, the typical size of the pores is 1-100 nm, and the density can be as low as 3 kg / m 3 3kg / m4. The material has a low thermal conductivity at room temperature. Due to these characteristics, the aerogel material has a wide application potential in the fields of heat, sound, light, microelectronics and particle detection. At present, the most widely used field of aerogel is the field of thermal insulation. Due to the unique nanostructure of aerogel, the convection conduction, solid phase conduction and thermal radiation can be effectively reduced.

[0003] Traditional aerogel materials are mostly pearl necklace-like structures formed by nanoparticle accumulation. In the drying process, a supercritical drying process is often required, which greatly increases the preparation period and cost. In addition, the aerogel material with this structure is brittle, and needs to be structurally reinforced in practical application. However, the structural reinforcement process in the prior art will increase the density, increase the solid phase thermal conductivity, and increase the process complexity. In addition, some methods for strengthening the skeleton of aerogel material have good structural strength, but these methods often require a complex high-temperature sintering process to increase the size of the skeleton to improve the strength of the material, thus bringing new problems such as high thermal conductivity and brittleness. With the development of science and technology, higher requirements for the strength, temperature resistance, lightness and / or thermal insulation performance of aerogel thermal insulation materials are put forward in various fields.

[0004] In summary, it is necessary to provide a method for preparing high-temperature-resistant and high-strength aerogel material through normal-pressure drying and high-temperature-resistant and high-strength aerogel material prepared by the method. SUMMARY

[0005] In order to solve one or more technical problems in the prior art, the present application provides a method for preparing high-temperature-resistant and high-strength aerogel material through normal-pressure drying and high-temperature-resistant and high-strength aerogel material prepared by the method.

[0006] In a first aspect, the present application provides a method for preparing high-temperature-resistant and high-strength aerogel material through normal-pressure drying, and the method comprises the following steps:

[0007] (1) mixing alumina nano-powder, aluminum silicate fiber, alumina fiber and hydrochloric acid with water to obtain a mixed solution, and then subjecting the mixed solution to hydrothermal reaction at 200-300°C to obtain a gel; preferably, the mixed solution further contains silicon carbide nano-powder;

[0008] (2) soaking the gel in water for 6-72h to obtain a soaked gel;

[0009] (3) subjecting the soaked gel obtained in step (2) to normal pressure drying to obtain an aerogel material;

[0010] (4) subjecting the aerogel material obtained in step (3) to heat treatment in air atmosphere to obtain a high-temperature-resistant and high-strength aerogel material.

[0011] Preferably, the mass fraction of the alumina nano-powder contained in the mixed solution is 5-20%; the mass fraction of the silicon carbide nano-powder contained in the mixed solution is 0.5-10%, preferably 1-5%.

[0012] Preferably, the sum of the mass fractions of the aluminum silicate fiber and the alumina fiber contained in the mixed solution is 1-15%, preferably 1-4%.

[0013] Preferably, the mass ratio of the amount of the aluminum silicate fiber to the amount of the alumina fiber is (1-3):1, preferably 2:1.

[0014] Preferably, the hydrothermal reaction is performed for 1-48h, preferably 3-12h.

[0015] Preferably, the normal pressure drying is performed at a temperature of 25-80°C for 12-120h.

[0016] Preferably, the heat treatment is performed at a temperature of 600-1000°C for 0.5-2h.

[0017] Preferably, the concentration of the hydrochloric acid is 0.1-5mol / L; and / or the amount of the hydrochloric acid accounts for 0.3-5% of the total mass of the mixed solution.

[0018] Preferably, the high-temperature-resistant and high-strength aerogel material has a cage-like structure surrounded by nanometer belts.

[0019] The present application provides in a second aspect a high-temperature-resistant and high-strength aerogel material prepared by the method described in the first aspect of the present application.

[0020] Compared with the prior art, the present application has at least the following beneficial effects:

[0021] (1) Compared with the traditional pearl necklace-shaped aerogel material, the high-temperature-resistant and high-strength aerogel material prepared by the application has a cage-shaped nano structure surrounded by nanobands, the porosity can be as high as about 95%, the material has the characteristics of ultra-lightness, the heat-resistant temperature can reach more than 1200 DEG C, and the mechanical strength is better.

[0022] (2) The method of the application uses an aqueous phase as a reaction medium, and does not need a supercritical drying process and a relatively high-temperature heat treatment process or a complex step-by-step heat treatment process, and the use of organic solvents in the preparation process is avoided, which causes environmental pollution and waste, and the high-temperature-resistant and high-strength aerogel material can be directly obtained by soaking the gel in water, and then through a normal pressure drying and a relatively low-temperature heat treatment step.

[0023] (3) The gel process in the preparation method of the application is a hydrothermal process, which is different from the traditional RTM pressing gel process, and is not limited by the shape and size of the reinforcing body, and can prepare aerogel materials of any shape and thickness.

[0024] (4) In some preferred technical solutions, the high-temperature-resistant and high-strength aerogel material prepared by the application has very excellent heat insulation performance at high temperature due to the doping of uniform anti-radiation agent silicon carbide nano powder.

[0025] (5) The high-temperature-resistant and high-strength aerogel material prepared by the application has a density as low as 0.2g / cm 3 , and has the characteristics of ultra-low density compared with other aerogel materials of the same strength; the aerogel material prepared by the method of the application has excellent high-temperature-resistant performance under the premise of maintaining low thermal conductivity, and can realize long-time 1200 DEG C heat insulation application; the application obtains a high-temperature-resistant and high-strength aerogel material with good temperature resistance, high strength, low density and good high-temperature heat insulation performance. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the preparation flowchart of some specific embodiments of the application.

[0027] Figure 2 is the SEM diagram of the high-temperature-resistant and high-strength aerogel material prepared in Example 1 of the application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme of the application will be described clearly and completely in combination with the embodiments of the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0029] The present application provides, in a first aspect, a method for preparing a high-temperature-resistant and high-strength aerogel material by atmospheric pressure drying, a preparation flowchart of which is shown, for example, as follows Figure 1 The method comprises the following steps:

[0030] (1) uniformly mixing alumina nano-powder, aluminum silicate fiber, alumina fiber and hydrochloric acid with water to obtain a mixture, and then subjecting the mixture to hydrothermal reaction at 200-300°C to obtain a gel; preferably, the mixture further comprises silicon carbide nano-powder, i.e., step (1) is: uniformly mixing alumina nano-powder, aluminum silicate fiber, alumina fiber, silicon carbide nano-powder and hydrochloric acid with water to obtain a mixture, and then subjecting the mixture to hydrothermal reaction at 200-300°C to obtain a gel;

[0031] (2) soaking the gel obtained in step (1) in water for 6-72h (e.g., 6, 12, 18, 24, 30, 36, 42, 48, 60, 66 or 72h) to obtain a soaking-treated gel; in the present application, the gel is aged by soaking in water, which has good diffusivity and uniformity and can uniformly penetrate into the gel, making the aging process more uniform, and the water-soaking aging can provide uniform wetting conditions, which is conducive to the uniform progress of the internal reactions of the gel and the formation of a more delicate pore structure, and is beneficial to reducing the cracks and defects of the aerogel formed finally, providing a higher specific surface area, and the soaking aging process can enhance the uniformity and connectivity of the gel material, and the aging in water is conducive to the formation of a more stable gel structure, thus being beneficial to the subsequent atmospheric pressure drying process;

[0032] (3) subjecting the soaking-treated gel obtained in step (2) to atmospheric pressure drying to obtain an aerogel material;

[0033] (4) subjecting the aerogel material obtained in step (3) to heat treatment in an air atmosphere to obtain a high-temperature-resistant and high-strength aerogel material.

[0034] The present application finds that the mixed solution containing alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid is subjected to hydrothermal reaction, in which the aluminum silicate fiber and the alumina fiber can participate in the reaction, so that the alumina nanopowder can interact with the aluminum silicate fiber and the alumina fiber, which can lead to cross-linking, cross-connection or wrapping of the alumina nanopowder with the aluminum silicate fiber and the alumina fiber at the nanometer scale, to construct a precursor (gel) of a cage structure surrounded by nanobands, and in the construction of the gel, uniform doping of the anti-radiation agent silicon carbide nanopowder is preferably performed; in the present application, the aluminum silicate fiber can be dominant and the alumina fiber can be auxiliary, and the aluminum silicate fiber and the alumina fiber together can play the role of a template and a supporting agent, can guide the alumina nanopowder to form a gel, can provide a template effect for the formation of the cage structure surrounded by nanobands, and can help to maintain the stability and strength of the gel structure, which is conducive to the subsequent normal pressure drying process, and after normal pressure drying and heat treatment, the cage structure surrounded by nanobands of the aerogel material is maintained and enhanced in stability, and finally a high-temperature-resistant and high-strength aerogel material with a cage structure surrounded by nanobands is constructed, for example, as shown in Figure 2 The present application finds that the mixed solution containing alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid is subjected to hydrothermal reaction, in which the aluminum silicate fiber and the alumina fiber can participate in the reaction, so that the alumina nanopowder can interact with the aluminum silicate fiber and the alumina fiber, which can lead to cross-linking, cross-connection or wrapping of the alumina nanopowder with the aluminum silicate fiber and the alumina fiber at the nanometer scale, to construct a precursor (gel) of a cage structure surrounded by nanobands, and in the construction of the gel, uniform doping of the anti-radiation agent silicon carbide nanopowder is preferably performed; in the present application, the aluminum silicate fiber can be dominant and the alumina fiber can be auxiliary, and the aluminum silicate fiber and the alumina fiber together can play the role of a template and a supporting agent, can guide the alumina nanopowder to form a gel, can provide a template effect for the formation of the cage structure surrounded by nanobands, and can help to maintain the stability and strength of the gel structure, which is conducive to the subsequent normal pressure drying process, and after normal pressure drying and heat treatment, the cage structure surrounded by nanobands of the aerogel material is maintained and enhanced in stability, and finally a high-temperature-resistant and high-strength aerogel material with a cage structure surrounded by nanobands is constructed, for example, as shown in

[0035] Compared with the traditional pearl necklace-shaped aerogel material, the high-temperature-resistant and high-strength aerogel material prepared by the present application has a cage nanostructure surrounded by nanobands, and the porosity can be as high as 90% or more, and has an ultra-light property, which can be as low as 0.2g / cm 3The left and right, the heat resistance temperature can reach 1200 DEG C above, can realize long time 1200 DEG C heat insulation application, and has better mechanical strength;The application obtains a kind of high-temperature resistant high-strength aerogel material with good high-temperature insulation performance, good high-temperature resistance, high strength and low density.The method of the present application can directly obtain the high-temperature resistant high-strength aerogel material by directly drying in water and relatively low-temperature heat treatment steps without supercritical drying process and complex step-by-step heat treatment process or relatively high-temperature heat treatment process, which can simplify the preparation process, reduce the process steps and operation difficulty, reduce the complexity and cost of preparation process, help to save energy, avoid environmental pollution and waste caused by the use of organic solvents.The present application uses more simplified, more environmentally friendly and more easily controlled steps, which helps to obtain high-temperature resistant high-strength aerogel materials with more stable quality and superior performance.

[0036] According to some preferred embodiments, the mass fraction of the aluminum oxide nano-powder contained in the mixed solution is 5-20% (for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%), more preferably 8-20%; the mass fraction of the silicon carbide nano-powder contained in the mixed solution is 0.5-10% (for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%), preferably 1-5%.

[0037] According to some preferred embodiments, the sum of the mass fractions of the aluminum silicate fibers and the aluminum oxide fibers contained in the mixed solution is 1-15% (for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%), preferably 1-4% (for example, 1%, 2%, 3% or 4%).

[0038] According to some preferred embodiments, the mass ratio of the amount of the aluminum silicate fibers to the amount of the aluminum oxide fibers is (1-3):1 (for example, 1:1, 1.5:1, 2:1, 2.5:1 or 3:1), preferably 2:1.

[0039] In the present application, the mass ratio of the amount of the aluminum silicate fibers to the amount of the aluminum oxide fibers is preferably (1-3):1, and by reasonably matching the amounts, the advantages of both can be comprehensively utilized to obtain better comprehensive performance, which helps to obtain high-temperature resistant high-strength aerogel materials with superior performance.If the matching of the amounts of the aluminum silicate fibers and the aluminum oxide fibers is not within a reasonable range, it may affect the pore structure and skeleton strength of the aerogel material, thereby affecting the porosity, specific surface area and thermal conductivity of the aerogel material.

[0040] The present application does not make specific limitations on the alumina nanopowder, silicon carbide nanopowder, aluminum silicate fiber and alumina fiber, and products available on the market or synthesized by existing methods can be used; preferably, the particle size of the alumina nanopowder is 10-100 nm, preferably 10-25 nm; the particle size of the silicon carbide nanopowder is 20-100 nm, preferably 20-40 nm; the length of the aluminum silicate fiber is 1-3 mm, and the diameter is 2-9 μm; the length of the alumina fiber is 1-5 mm, and the diameter is 4-9 μm.

[0041] According to some preferred embodiments, the time of the hydrothermal reaction is 1-48 h (e.g. 1, 3, 5, 10, 12, 15, 18, 20, 25, 30, 36, 40, 45 or 48 h), preferably 3-12 h (e.g. 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12 h).

[0042] According to some preferred embodiments, the temperature of the normal pressure drying is 25-80℃ (e.g. 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃), and the time of the normal pressure drying is 12-120 h (e.g. 12, 24, 36, 48, 60, 72, 84, 96, 108 or 120 h), preferably 24-48 h.

[0043] According to some preferred embodiments, the temperature of the heat treatment is 600-1000℃ (e.g. 600℃, 700℃, 800℃, 900℃ or 1000℃), preferably 600-800℃ (e.g. 600℃, 700℃ or 800℃), and the time of the heat treatment is 0.5-2 h (e.g. 0.5, 1, 1.5 or 2 h).

[0044] Compared with heat treatment at a relatively high temperature of 1000-1200℃, the present application can prepare high-temperature-resistant and high-strength aerogel materials with comparable effects at a relatively low temperature of 600-1000℃.

[0045] According to some embodiments, the concentration of the hydrochloric acid is 0.1-5 mol / L, preferably 1-5 mol / L; and / or the amount of the hydrochloric acid accounts for 0.3-5% of the total mass of the mixed solution, preferably 1-3%.

[0046] According to some specific embodiments, the preparation process of the method for preparing high-temperature-resistant and high-strength aerogel materials by normal pressure drying of the present application is shown in, for example, Figure 1 The method comprises the following steps:

[0047] (1) mixing alumina nanopowder, aluminum silicate fiber, alumina fiber, silicon carbide nanopowder and hydrochloric acid (hydrochloric acid solution) with water to obtain a mixed solution, mixing the alumina nanopowder, aluminum silicate fiber, alumina fiber and silicon carbide nanopowder uniformly by a high-speed dispersion machine, and then placing the mixed solution in a water thermal reaction at 200-300°C for 1-48h to obtain a gel; the mass fraction of the alumina nanopowder contained in the mixed solution is 5-20%, the sum of the mass fractions of the aluminum silicate fiber and the alumina fiber contained in the mixed solution is 1-15%, and the content of the silicon carbide nanopowder contained in the mixed solution is 0.5-10%; in step (1), the mixing is uniformly performed by high-speed dispersion, specifically: mixing the alumina nanopowder, aluminum silicate fiber, alumina fiber, silicon carbide nanopowder and hydrochloric acid with water, and then performing high-speed dispersion in a high-speed dispersion machine at a speed of 1000-8000r / min for 5-120min; in the present application, the mixed solution is placed in a sealed container for water thermal reaction at 200-300°C; in the present application, the water thermal reaction needs to be ensured to be performed under a sealed condition, and the material of the sealed container needs to be ensured to be a material that does not react with the system;

[0048] (2) soaking the obtained gel in pure water for 6-72h;

[0049] (3) performing normal pressure drying on the obtained soaked gel material, the normal pressure drying temperature is 25-80°C, and the normal pressure drying time is 12-120h; the normal pressure drying is, for example, oven drying under normal pressure;

[0050] (4) performing heat treatment on the dried aerogel material, the air atmosphere heat treatment temperature is 600-1000°C, and a high-temperature-resistant and high-strength aerogel material (also referred to as a high-temperature-resistant and high-efficiency aerogel material) is prepared.

[0051] According to some preferred embodiments, the high-temperature-resistant and high-strength aerogel material has a cage-like structure surrounded by nanobands, for example, as shown in Figure 2 , and Figure 2 It is shown that the high-temperature-resistant and high-strength aerogel material prepared in the present application has a cage-like structure surrounded by nanobands, specifically, the skeleton structure of the high-temperature-resistant and high-strength aerogel material in the present application is a cage-like structure surrounded by nanobands.

[0052] According to some preferred embodiments, the density of the high-temperature-resistant and high-strength aerogel material is as low as 0.23g / cm 3 , the porosity is as high as 93.8%, the specific surface area is greater than 162m 2 / g, the compressive strength at a 10% compression amount is as high as 1.43MPa, the thermal conductivity at 1000°C is as low as 0.065W / (m·K), and the heat-resistant temperature is above 1200°C.

[0053] The present application provides, in a second aspect, a high-temperature-resistant and high-strength aerogel material prepared by the method of the first aspect.

[0054] The present application will be further described below by way of examples, but the scope of protection of the present application is not limited to these examples.

[0055] Example 1

[0056] (1) The alumina nano-powder, aluminum silicate fiber, alumina fiber and hydrochloric acid were mixed with water, and uniformly mixed in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution was subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of the alumina nano-powder contained in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber contained in the mixed solution was 2%, and the mass fraction of the alumina fiber contained in the mixed solution was 1%; the amount of the hydrochloric acid was 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0057] (2) The obtained gel was soaked in pure water at room temperature of 25℃ for 24h to obtain a soaking treatment gel.

[0058] (3) The obtained soaking treatment gel was subjected to normal pressure drying, and the normal pressure drying temperature was 60℃, and the normal pressure drying time was 24h to obtain an aerogel material.

[0059] (4) The obtained aerogel material was subjected to heat treatment to obtain a high-temperature-resistant and high-strength aerogel material; the heat treatment temperature was 600℃, the heat treatment time was 1h, and the heat treatment was carried out in an air atmosphere.

[0060] The high-temperature-resistant and high-strength aerogel material prepared in this example has good structural strength, and when the heat insulation performance test is carried out, it is found that the surface of the high-temperature-resistant and high-strength aerogel material has no loss of luster, no discoloration, and no peeling.

[0061] The density of the high-temperature-resistant and high-strength aerogel material prepared in this example is 0.2g / cm 3 , and the specific surface area is 152m 2 / g, the porosity is 93.5%, the compression strength at 10% compression amount is 1.3 MPa, and the heat resistance temperature is 1200℃, and the high-temperature-resistant and high-strength aerogel material has good heat resistance, large specific surface area, small porosity, high strength, low density, and good heat insulation performance; the heat resistance temperature is tested by heat treating (air atmosphere) the aerogel material finally prepared in each example at a certain high-temperature for 2h, and the linear shrinkage rate of the aerogel material is not greater than 5%, which indicates that the aerogel material can resist the high-temperature; for this example, the high-temperature-resistant and high-strength aerogel material prepared in this example is heat treated (air atmosphere) at 1200℃ for 2h, the linear shrinkage rate of the aerogel material is not greater than 5%, the heat resistance temperature is 1200℃, and the long-time 1200℃ heat insulation application can be realized.

[0062] Example 2

[0063] (1) The alumina nano powder, aluminum silicate fiber, alumina fiber, silicon carbide nano powder and hydrochloric acid were mixed with water, and uniformly mixed by dispersing in a high-speed dispersing machine at a speed of 5000r / min for 30min to obtain a mixed solution; then the mixed solution was subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of the alumina nano powder contained in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber contained in the mixed solution was 2%, the mass fraction of the alumina fiber contained in the mixed solution was 1%, the mass fraction of the silicon carbide nano powder contained in the mixed solution was 1%, and the amount of the hydrochloric acid accounted for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2mol / L.

[0064] (2) The obtained gel was soaked in pure water at room temperature 25℃ for 24h to obtain a soaking treatment gel.

[0065] (3) The obtained soaking treatment gel was subjected to normal pressure drying, the normal pressure drying temperature was 60℃, and the normal pressure drying time was 24h to obtain an aerogel material.

[0066] (4) The obtained aerogel material was subjected to heat treatment to obtain a high-temperature-resistant and high-strength aerogel material; the heat treatment temperature was 600℃, the heat treatment time was 1h, and the heat treatment was carried out in an air atmosphere.

[0067] The high-temperature-resistant and high-strength aerogel material prepared in this example has good structural strength, and when the heat insulation performance is tested, it is found that the surface of the high-temperature-resistant and high-strength aerogel material has no loss of luster, no discoloration, and no shedding.

[0068] The density of the high-temperature-resistant and high-strength aerogel material prepared in this example is 0.23g / cm 3 , the thermal conductivity at 1000℃ is 0.065W / (m·K), and the specific surface area is 162m 2The aerogel material has good temperature resistance, large specific surface area, small porosity, high strength, low density, and good high-temperature heat insulation performance.

[0069] Example 3

[0070] Example 3 is basically the same as Example 2, except that:

[0071] (1) The alumina nano powder, aluminum silicate fiber, silicon carbide nano powder and hydrochloric acid are mixed with water, and are uniformly mixed in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution is subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of the alumina nano powder contained in the mixed solution is 10%, the mass fraction of the aluminum silicate fiber contained in the mixed solution is 3%, and the mass fraction of the silicon carbide nano powder contained in the mixed solution is 1%; the amount of the hydrochloric acid accounts for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid is 2 mol / L.

[0072] The aerogel material prepared through steps (1) to (4) in this example has good structural strength, but shrinks greatly during normal pressure drying, has large material density, small specific surface area, and significantly increased thermal conductivity, and the performance test results are shown in Table 1.

[0073] Example 4

[0074] Example 4 is basically the same as Example 2, except that:

[0075] (1) The alumina nano powder, aluminum silicate fiber, silicon carbide nano powder and hydrochloric acid are mixed with water, and are uniformly mixed in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution is subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of the alumina nano powder contained in the mixed solution is 10%, the mass fraction of the aluminum silicate fiber contained in the mixed solution is 3%, and the mass fraction of the silicon carbide nano powder contained in the mixed solution is 1%; the amount of the hydrochloric acid accounts for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid is 2 mol / L.

[0076] The aerogel material prepared through steps (1) to (4) in this example has good structural strength, but shrinks during normal pressure drying, has large material density, small specific surface area, and increased thermal conductivity, and the performance test results are shown in Table 1.

[0077] Example 5

[0078] Example 5 is substantially the same as Example 2, except that:

[0079] (1) The alumina nanopowder, aluminum silicate fiber, alumina fiber, silicon carbide nanopowder and hydrochloric acid were mixed with water, and uniformly mixed in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution. Then, the mixed solution was subjected to hydrothermal reaction at 220°C for 5h to obtain a gel. The mass fraction of the alumina nanopowder in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber in the mixed solution was 0.5%, the mass fraction of the alumina fiber in the mixed solution was 0.5%, and the mass fraction of the silicon carbide nanopowder in the mixed solution was 1%. The amount of the hydrochloric acid accounted for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0080] The performance test results of the high-temperature-resistant and high-strength aerogel material prepared through steps (1) to (4) in this example are shown in Table 1.

[0081] Example 6

[0082] Example 6 is substantially the same as Example 2, except that:

[0083] (1) The alumina nanopowder, aluminum silicate fiber, alumina fiber, silicon carbide nanopowder and hydrochloric acid were mixed with water, and uniformly mixed in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution. Then, the mixed solution was subjected to hydrothermal reaction at 220°C for 5h to obtain a gel. The mass fraction of the alumina nanopowder in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber in the mixed solution was 10%, the mass fraction of the alumina fiber in the mixed solution was 1%, and the mass fraction of the silicon carbide nanopowder in the mixed solution was 1%. The amount of the hydrochloric acid accounted for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0084] The performance test results of the aerogel material prepared through steps (1) to (4) in this example are shown in Table 1.

[0085] Example 7

[0086] Example 7 is substantially the same as Example 2, except that:

[0087] (1) Al2O3 nano powder, aluminum silicate fiber, Al2O3 fiber, SiC nano powder and hydrochloric acid were mixed with water in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution was subjected to hydrothermal reaction at 150℃ for 5h to obtain a gel; the mass fraction of Al2O3 nano powder contained in the mixed solution was 10%, the mass fraction of aluminum silicate fiber contained in the mixed solution was 2%, the mass fraction of Al2O3 fiber contained in the mixed solution was 1%, the mass fraction of SiC nano powder contained in the mixed solution was 1%, and the amount of hydrochloric acid accounted for 1.5% of the total weight of the mixed solution, and the concentration of hydrochloric acid was 2 mol / L.

[0088] In this embodiment, the temperature of the hydrothermal reaction is relatively low, and a very complete block cannot be formed, and the aerogel material shrinks, resulting in a significant decrease in the porosity and specific surface area of the prepared aerogel material. The other performance test results are shown in Table 1.

[0089] Example 8

[0090] Example 8 is basically the same as Example 2, except that:

[0091] (1) Al2O3 nano powder, aluminum silicate fiber, Al2O3 fiber, SiC nano powder and hydrochloric acid were mixed with water in a high-speed dispersion machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution was subjected to hydrothermal reaction at 150℃ for 5h to obtain a gel; the mass fraction of Al2O3 nano powder contained in the mixed solution was 10%, the mass fraction of aluminum silicate fiber contained in the mixed solution was 2%, the mass fraction of Al2O3 fiber contained in the mixed solution was 1%, the mass fraction of SiC nano powder contained in the mixed solution was 1%, and the amount of hydrochloric acid accounted for 1.5% of the total weight of the mixed solution, and the concentration of hydrochloric acid was 2 mol / L.

[0092] The performance test results of the aerogel material prepared by steps (1) to (4) in this embodiment are shown in Table 1.

[0093] The aerogel material prepared by steps (1) to (4) in this embodiment has good structural strength, but the specific surface area of the material is very small, and the thermal conductivity increases at 1000℃.

[0094] Example 9

[0095] Example 9 is basically the same as Example 2, except that:

[0096] (1) mixing alumina nano-powder, aluminum silicate fiber, alumina fiber, silicon carbide nano-powder and hydrochloric acid with water, and uniformly mixing the mixture in a high-speed dispersion machine at a rotation speed of 5000 r / min for 30 min to obtain a mixed solution; then placing the mixed solution in a hydrothermal reaction at 220 ℃ for 5 h to obtain a gel; the mass fraction of the alumina nano-powder contained in the mixed solution is 4%, the mass fraction of the aluminum silicate fiber contained in the mixed solution is 2%, the mass fraction of the alumina fiber contained in the mixed solution is 1%, and the mass fraction of the silicon carbide nano-powder contained in the mixed solution is 1%; the amount of the hydrochloric acid accounts for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid is 2 mol / L.

[0097] The performance test results of the aerogel material prepared through steps (1) to (4) in this example are shown in Table 1.

[0098] Example 10

[0099] Example 10 is basically the same as Example 2, except that:

[0100] (4) performing heat treatment on the obtained aerogel material to obtain a high-temperature-resistant and high-strength aerogel material; the heat treatment temperature is 500 ℃, the heat treatment time is 1 h, and the heat treatment is performed in an air atmosphere.

[0101] The performance test results of the aerogel material prepared through steps (1) to (4) in this example are shown in Table 1.

[0102] Comparative Example 1

[0103] Comparative Example 1 is basically the same as Example 2, except that:

[0104] (2) aging the obtained gel in an unsealed environment in air at 60 ℃ for 2 h to obtain an aged gel block; using the aged gel block to perform subsequent steps (3) and (4).

[0105] The performance test results of the aerogel material prepared through steps (1) to (4) in this example are shown in Table 1.

[0106] Comparative Example 2

[0107] Comparative Example 2 is basically the same as Example 2, except that:

[0108] (1) Al2O3 nano powder, mullite fiber, basalt fiber, SiC nano powder and hydrochloric acid were mixed with water in a high-speed disperser at a speed of 5000 r / min for 30 min to obtain a mixture; then the mixture was subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of Al2O3 nano powder in the mixture was 10%, the mass fraction of mullite fiber in the mixture was 2%, the mass fraction of basalt fiber in the mixture was 1%, and the mass fraction of SiC nano powder in the mixture was 1%; the amount of hydrochloric acid accounted for 1.5% of the total weight of the mixture, and the concentration of hydrochloric acid was 2 mol / L.

[0109] The performance test results of the aerogel material prepared by steps (1) to (4) of the present example are shown in Table 1.

[0110] Example 1

[0111] (1) Al2O3 nano powder, mullite fiber, basalt fiber, SiC nano powder and hydrochloric acid were mixed with water in a high-speed disperser at a speed of 5000 r / min for 30 min to obtain a mixture; then the mixture was subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of Al2O3 nano powder in the mixture was 10%, the mass fraction of mullite fiber in the mixture was 2%, the mass fraction of basalt fiber in the mixture was 1%, and the mass fraction of SiC nano powder in the mixture was 1%; the amount of hydrochloric acid accounted for 1.5% of the total weight of the mixture, and the concentration of hydrochloric acid was 2 mol / L.

[0112] (2) The obtained gel was aged in an unsealed environment at 60℃ for 2h to obtain an aged gel.

[0113] (3) The aged gel was subjected to solvent replacement and supercritical drying in sequence to obtain an aerogel material; the specific steps were as follows: ethanol was used as the solvent for solvent replacement, and the volume of the solvent was 10 times the volume of the gel after soaking treatment, and the solvent replacement was performed for 3 times, and the time for each solvent replacement was 3 days; then the supercritical carbon dioxide drying process was performed, and the temperature for supercritical drying was 50℃, the pressure was 14 MPa, and the time was 24h.

[0114] (4) The obtained aerogel was subjected to heat treatment to obtain a composite aerogel material; the heat treatment temperature was 1150℃, the heat treatment time was 0.5h, and the heat treatment was performed in an air atmosphere.

[0115] The performance test results of the aerogel material prepared by steps (1) to (4) of the present example are shown in Table 1.

[0116] Example 1

[0117] Comparative Example 4 is substantially the same as Example 2, except that:

[0118] (1) the alumina nanopowder, the silicon carbide nanopowder and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed dispersion machine at a rotation speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution was subjected to hydrothermal reaction at 220℃ for 5h to obtain a gel; the mass fraction of the alumina nanopowder contained in the mixed solution was 10%, the mass fraction of the silicon carbide nanopowder contained in the mixed solution was 1%; the amount of hydrochloric acid was 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0119] The performance test results of the aerogel material prepared by the steps (1) to (4) of the present comparative example are shown in Table 1.

[0120]

[0121]

[0122] In Table 1, the symbol “—” indicates that the performance index is not tested.

[0123] The part of the present application not described in detail is the technology known to those skilled in the art.

[0124] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing high-temperature resistant and high-strength aerogel materials by atmospheric pressure drying, characterized in that, The method includes the following steps: (1) Alumina nanoparticles, aluminum silicate fibers, aluminum oxide fibers and hydrochloric acid are mixed evenly with water to obtain a mixture. Then, the mixture is placed at 200~300℃ for hydrothermal reaction to obtain a gel. The mixture also contains silicon carbide nanoparticles. The mass fraction of aluminum oxide nanoparticles in the mixture is 5~20%. The mass fraction of silicon carbide nanoparticles in the mixture is 0.5~10%. The sum of the mass fractions of aluminum silicate fibers and aluminum oxide fibers in the mixture is 1~4%. The mass ratio of aluminum silicate fibers to aluminum oxide fibers is (1~3):

1. (2) Soak the gel in water for 6-72 hours to obtain the soaking-treated gel; (3) The soaking gel obtained in step (2) is dried under normal pressure to obtain aerogel material; (4) The aerogel material obtained in step (3) is heat-treated in an air atmosphere to obtain a high-temperature resistant and high-strength aerogel material; the heat treatment temperature is 600~800℃ and the heat treatment time is 0.5~2h; the high-temperature resistant and high-strength aerogel material has a cage-like structure surrounded by nanobelts.

2. The method according to claim 1, characterized in that: The mixture contains 1-5% silicon carbide nanoparticles by mass.

3. The method according to claim 1 or 2, characterized in that: The mass ratio of the aluminum silicate fiber to the alumina fiber is 2:

1.

4. The method according to claim 1 or 2, characterized in that: The hydrothermal reaction time is 1 to 48 hours.

5. The method according to claim 4, characterized in that: The hydrothermal reaction takes 3 to 12 hours.

6. The method according to claim 1 or 2, characterized in that: The temperature for atmospheric pressure drying is 25~80℃, and the drying time is 12~120h.

7. The method according to claim 1 or 2, characterized in that: The concentration of the hydrochloric acid is 0.1~5 mol / L; and / or The amount of hydrochloric acid used accounts for 0.3-5% of the total mass of the mixture.

8. A high-temperature resistant and high-strength aerogel material prepared by the method of any one of claims 1 to 7.

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