High-temperature-resistant and high-strength aerogel material and preparation method thereof

Abstract

The application relates to a high-temperature-resistant and high-strength aerogel material and a preparation method thereof, and 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 150-300 DEG C to obtain a gel; soaking the gel in water; performing normal-pressure drying on the soaked soaking treatment gel to obtain an aerogel material; and performing heat treatment on the aerogel material 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 strips, 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, low density and low thermal conductivity 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 high-temperature-resistant and high-strength aerogel material and a preparation method thereof. BACKGROUND

[0002] Nanoporous aerogel (aerogel for short) material is a gel material with gas as a dispersion medium, and is a nanoporous solid material with a 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 <3> at room temperature. Due to these characteristics, the aerogel material has a wide application potential in the fields of thermotics, acoustics, optics, microelectronics and particle detection. At present, the most widely used field of aerogel is the field of thermal insulation. Due to the unique nanometer structure 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 actual 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 high-temperature-resistant and high-strength aerogel material and a preparation method thereof. SUMMARY

[0005] In order to solve one or more technical problems in the prior art, the present application provides a high-temperature-resistant and high-strength aerogel material and a preparation method thereof.

[0006] The present application provides, in a first aspect, a preparation method of a high-temperature-resistant and high-strength aerogel material, which comprises the following steps:

[0007] (1) uniformly mixing alumina nano powder, aluminum silicate fiber, alumina fiber and hydrochloric acid with water to obtain a mixed solution, and then placing the mixed solution in a hydrothermal reaction at 150-300℃ to obtain a gel;

[0008] (2) soaking the gel in water to obtain a soaking-treated gel;

[0009] (3) performing normal-pressure drying on the soaking-treated gel obtained in step (2) to obtain an aerogel material;

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

[0011] Preferably, the mass fraction of the aluminum oxide nano-powder contained in the mixed solution is 5-20%.

[0012] Preferably, the sum of the mass fractions of the aluminum silicate fibers and the aluminum oxide fibers contained in the mixed solution is 1-15%.

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

[0014] Preferably, the time of the hydrothermal reaction is 1-48h, preferably 3-12h; and / or the time of the soaking is 6-72h.

[0015] Preferably, the temperature of the normal-pressure drying is 25-80℃, and the time of the normal-pressure drying is 12-120h.

[0016] Preferably, the temperature of the heat treatment is 600-1000℃, and the time of the heat treatment is 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 nanobands.

[0019] The present application provides, in a second aspect, a high-temperature-resistant and high-strength aerogel material prepared by the preparation 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 present application has a cage-like nanostructure surrounded by nanobands, the porosity can be as high as about 95%, has the characteristics of ultra-lightness, the heat-resistant temperature can be above 1200℃, and has better mechanical strength.

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

[0023] (3) The gel process in the preparation method of the present 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) The high-temperature-resistant and high-strength aerogel material prepared by the present application has a density as low as 0.2 g / cm 3 , which 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 present application has excellent high-temperature resistance under the premise of maintaining low thermal conductivity, and can realize long-time 1200℃ thermal insulation application; the present application obtains a high-temperature-resistant and high-strength aerogel material with good temperature resistance, high strength, low density and good thermal insulation performance. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is the preparation flow chart of the present application.

[0026] Figure 2 is the SEM image of the high-temperature-resistant and high-strength aerogel material prepared in Example 1 of the present application.

[0027] Figure 3 is the macroscopic optical photograph of the heat treatment of the high-temperature-resistant and high-strength aerogel material prepared in Example 1 of the present application; in the figure: (a) is the macroscopic optical photograph of the heat treatment at 600℃ for 1h in Example 1; (b) is the macroscopic optical photograph of the high-temperature-resistant and high-strength aerogel material prepared in Example 1 after heat treatment at 1200℃ for 2h. DETAILED DESCRIPTION

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

[0029] The present application provides, in a first aspect, a preparation method of a high-temperature-resistant and high-strength aerogel material, and the preparation flow chart is shown in, for example, Figure 1 The method comprises the following steps:

[0030] (1) mixing alumina nanopowder, 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 150-300°C to obtain a gel; in some more preferred embodiments, the temperature of the hydrothermal reaction is 200-300°C;

[0031] (2) soaking the gel in water to obtain a soaking-treated gel; in the present application, the gel is aged by soaking in water, which has good diffusivity and uniformity, can uniformly penetrate into the gel, making the aging process more uniform, and the water soaking aging can provide uniform wetting conditions, which helps the uniform progress of the internal reaction of the gel, helps to form a more detailed pore structure, is conducive to reducing the cracks and defects of the aerogel formed finally, provides a higher specific surface area, and the soaking aging process can enhance the uniformity and connectivity of the gel material, and aging in water helps to form a more stable gel structure, thereby facilitating the subsequent normal pressure drying process;

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

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

[0034] The present application finds that subjecting a mixed solution containing alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid to hydrothermal reaction, in this hydrothermal process, the aluminum silicate fiber and alumina fiber can participate in the reaction, so that the alumina nanopowder can interact with the aluminum silicate fiber and alumina fiber, which can lead to cross-linking, cross-linking or wrapping of the alumina nanopowder with the aluminum silicate fiber and alumina fiber at the nanoscale, to construct a precursor (gel) of a cage structure surrounded by nanobands; in the present application, it is possible that the aluminum silicate fiber is the main one and the alumina fiber is the auxiliary one, and the aluminum silicate fiber and alumina fiber together can play the role of a template and a supporting agent, which can guide the alumina nanopowder to form a gel, provide a template effect for the formation of a cage structure surrounded by nanobands, and 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 2The present application finds that if only aluminum oxide nanometer powder is added in the mixed solution, the structure is prone to shrink during the preparation process, the cage structure surrounded by nanometer strips cannot be formed, the specific surface area of the aerogel material formed is significantly reduced, the density is increased, there are large gaps and interfaces, heat transfer is scattered more, the thermal conductivity is significantly increased, and the heat insulation performance is reduced. In the present application, only the hydrothermal reaction of the aluminum oxide nanometer powder, the aluminum silicate fiber and the aluminum oxide fiber together can ensure the formation of the cage structure surrounded by nanometer strips, and the aerogel material has high specific surface area, low density and low thermal conductivity, and the aerogel material has excellent heat insulation performance and high temperature resistance, and can withstand a temperature of 1200 DEG C or above. The present application finds that if the aluminum oxide nanometer powder is hydrothermally reacted with mullite fiber, basalt fiber or glass fiber, only physical doping and mutual winding between the aluminum oxide aerogel and the fiber can be realized, and the aerogel material with the cage structure surrounded by nanometer strips cannot be formed.

[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 nanometer strips, the porosity can be as high as 90% or above, has super light characteristics, and can be as low as 0.2 g / cm 3 Above, the heat resistance temperature can reach 1200 DEG C or above, the long-time 1200 DEG C heat insulation application can be realized, and the mechanical strength is better; the present application obtains a high temperature resistant and high strength aerogel material with good heat insulation performance, high strength and low density.

[0036] The method of the present application can directly obtain the high temperature resistant and high strength aerogel material by directly drying the gel in water and then performing a relatively low temperature heat treatment step, and the supercritical drying process and the complex step-by-step heat treatment process or the relatively high temperature heat treatment process can be simplified, the process steps and the operation difficulty are reduced, the complexity and the cost of the preparation process are reduced, energy saving is achieved, environmental pollution and waste caused by the use of organic solvents are avoided. The present application adopts a more simplified, more environmentally friendly and more easily controlled step, which is helpful to obtain a high temperature resistant and high strength aerogel material with more stable quality and more superior performance.

[0037] According to some preferred embodiments, the mass fraction of the aluminum oxide nanometer 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%), and more preferably 8-20%.

[0038] According to some preferred embodiments, the sum of the mass fraction of the aluminum silicate fibers and the aluminum oxide fibers in the mixed solution is 1-15% (e.g., 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%), preferably 1-4% (e.g., 1%, 2%, 3%, or 4%).

[0039] 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 (e.g., 1:1, 1.5:1, 2:1, 2.5:1, or 3:1), preferably 2:1.

[0040] 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. By a reasonable ratio, the advantages of both can be comprehensively utilized to obtain better comprehensive performance, which is helpful to obtain a high-temperature-resistant and high-strength aerogel material with superior performance. If the ratio 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.

[0041] The present application does not make specific limitations on the aluminum oxide nano powder, the aluminum silicate fibers, and the aluminum oxide fibers. Products available on the market or synthesized by existing methods can be used. Preferably, the particle size of the aluminum oxide nano powder is 10-100 nm, preferably 10-25 nm; the length of the aluminum silicate fibers is 1-3 mm, and the diameter is 2-9 μm; and the length of the aluminum oxide fibers is 1-5 mm, and the diameter is 4-9 μm.

[0042] 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); and / or the time of the soaking is 6-72 h (e.g., 6, 12, 18, 24, 30, 36, 42, 48, 60, 66, or 72 h). In the present application, the soaking is performed at room temperature, e.g., at room temperature of 20-35 °C for 6-72 h in water.

[0043] According to some preferred embodiments, the temperature of the normal-pressure drying is 25-80 °C (e.g., 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, or 80 °C), 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.

[0044] 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 0.5-2h (e.g. 0.5, 1, 1.5 or 2h).

[0045] The present application can produce high-temperature-resistant and high-strength aerogel materials with comparable effects by performing heat treatment at a relatively low temperature of 600-1000℃ compared to performing heat treatment at a relatively high temperature of 1000-1200℃.

[0046] According to some embodiments, the concentration of the hydrochloric acid is 0.1-5mol / L, preferably 1-5mol / 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%.

[0047] According to some specific embodiments, the preparation process of the high-temperature-resistant and high-strength aerogel material of the present application is, for example, as shown in Figure 1 The preparation method comprises the following steps:

[0048] (1) uniformly mix alumina nano powder, aluminum silicate fiber, alumina fiber and hydrochloric acid (hydrochloric acid solution) with water to obtain a mixed solution, uniformly mix the alumina nano powder and the aluminum silicate fiber and the alumina fiber by means of a high-speed dispersing machine, and then place the mixed solution in a sealed container for hydrothermal reaction at 150-300℃ for 1-48h to obtain a gel; the mass fraction of the alumina nano powder contained in the mixed solution is 5-20%, and the sum of the mass fractions of the aluminum silicate fiber and the alumina fiber contained in the mixed solution is 1-15%; in step (1), the uniform mixing is achieved by means of high-speed dispersion, specifically: after mixing the alumina nano powder, the aluminum silicate fiber, the alumina fiber and the hydrochloric acid with water, high-speed dispersion is performed in a high-speed dispersing 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 hydrothermal reaction at 150-300℃; in the present application, the hydrothermal reaction needs 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;

[0049] (2) immerse the obtained gel in pure water for 6-72h;

[0050] (3) perform normal-pressure drying on the obtained immersion-treated gel material, the normal-pressure drying temperature is 25-80℃, and the normal-pressure drying time is 12-120h to obtain an aerogel material; the normal-pressure drying is, for example, oven drying under normal pressure;

[0051] (4) heat treatment is performed on the dried aerogel material, and the heat treatment temperature is 600-1000℃.

[0052] According to some preferred embodiments, the high-temperature-resistant and high-strength aerogel material has a cage structure surrounded by nanobands, for example, as shown in Figure 2 Figure 2 It is shown that the high-temperature-resistant and high-strength aerogel material prepared in the application has a cage structure surrounded by nanobands, and in particular, the skeleton structure of the high-temperature-resistant and high-strength aerogel material in the application is a cage structure surrounded by nanobands.

[0053] According to some preferred embodiments, the density of the high-temperature-resistant and high-strength aerogel material is as low as 0.2 g / cm 3 , the porosity is as high as 93.5%, the specific surface area is not less than 152 m 2 / g, the compressive strength at 10% compression is as high as 1.3 MPa, the thermal conductivity is as low as 0.040 W / (m·K), and the heat-resistant temperature is above 1200℃.

[0054] The application provides in a second aspect a high-temperature-resistant and high-strength aerogel material prepared by the preparation method described in the first aspect of the application.

[0055] The application will be further described below by way of examples, but the scope of protection of the application is not limited to these examples.

[0056] Example 1

[0057] (1) Alumina nanometer powder, aluminum silicate fiber, alumina fiber and hydrochloric acid are mixed with water, and are uniformly mixed in a high-speed dispersing machine at a rotating 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 5 h to obtain a gel; the mass fraction of the alumina nanometer powder contained in the mixed solution is 10%, the mass fraction of the aluminum silicate fiber contained in the mixed solution is 2%, and the mass fraction of the alumina fiber 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.

[0058] (2) The obtained gel is soaked in pure water at room temperature of 25℃ for 24 h to obtain a soaking treatment gel.

[0059] (3) The obtained soaking treatment gel is subjected to normal pressure drying, and the normal pressure drying temperature is 60℃, and the normal pressure drying time is 24 h to obtain an aerogel material.

[0060] (4) Heat treatment is performed on the obtained aerogel material to obtain a high-temperature-resistant and high-strength aerogel material; the heat treatment temperature is 600℃, the heat treatment time is 1 h, and the heat treatment is performed in an air atmosphere. ​

[0061] The high-temperature-resistant and high-strength aerogel material prepared in this embodiment has good structural strength. When the thermal insulation performance test is performed, 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.

[0062] The density of the high-temperature-resistant and high-strength aerogel material prepared in this embodiment is 0.2 g / cm 3 , the thermal conductivity (thermal conductivity coefficient) at room temperature is 0.040 W / (m·K), the specific surface area is 152 m 2 / g, the porosity is 93.5%, the compressive strength under a 10% compression amount is 1.3 MPa, and the heat-resistant temperature is 1200℃. It is a high-temperature-resistant and high-strength aerogel material with good heat resistance, large specific surface area, small porosity, high strength, low density, and good thermal insulation performance. The test of the heat-resistant temperature is that the aerogel material finally prepared in each embodiment is heat-treated (air atmosphere) at a certain high-temperature for 2h, and the linear shrinkage rate of the aerogel material is not more than 5%, which indicates that the aerogel material can withstand the high temperature. For this embodiment, the high-temperature-resistant and high-strength aerogel material prepared in this embodiment is heat-treated (air atmosphere) at 1200℃ for 2h, and the linear shrinkage rate of the aerogel material is not more than 5%, the heat-resistant temperature is 1200℃, and the long-time 1200℃ thermal insulation application can be realized.

[0063] Example 2

[0064] Example 2 is basically the same as Example 1, except that:

[0065] (1) The alumina nano powder, alumina fiber and hydrochloric acid are mixed with water, dispersed in a high-speed dispersing machine at a speed of 5000 r / min for 30 min to obtain a mixed solution; then the mixed solution is placed in a 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 alumina fiber contained in the mixed solution is 3%; the amount of hydrochloric acid accounts for 1.5% of the total weight of the mixed solution, and the concentration of hydrochloric acid is 2 mol / L.

[0066] The aerogel material prepared by steps (1) to (4) in this embodiment has good structural strength, but it shrinks significantly during the normal pressure drying process, the material density is large, the specific surface area is small, and the thermal conductivity coefficient increases significantly. The performance test results are shown in Table 1.

[0067] Example 3

[0068] Example 3 is basically the same as Example 1, except that:

[0069] (1) Alumina nano-powder, aluminum silicate fiber and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed disperser at a speed of 5000 r / min for 30 min to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction at 220°C for 5 h to obtain a gel. The mass fraction of the alumina nano-powder in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber in the mixed solution was 3%, 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 2 mol / L.

[0070] The aerogel material prepared through steps (1) to (4) in this example had good structural strength, but shrinkage occurred during normal pressure drying, the material density was large, the specific surface area was small, and the thermal conductivity coefficient increased. The performance test results are shown in Table 1.

[0071] Example 4

[0072] Example 4 was basically the same as Example 1, except that:

[0073] (1) Alumina nano-powder, aluminum silicate fiber, alumina fiber and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed disperser at a speed of 5000 r / min for 30 min to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction at 220°C for 5 h to obtain a gel. The mass fraction of the alumina nano-powder in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber in the mixed solution was 0.5%, and the mass fraction of the alumina fiber in the mixed solution was 0.5%. 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.

[0074] 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.

[0075] Example 5

[0076] Example 5 was basically the same as Example 1, except that:

[0077] (1) Alumina nano-powder, aluminum silicate fiber, alumina fiber and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed disperser at a speed of 5000 r / min for 30 min to obtain a mixed solution. The mixed solution was subjected to hydrothermal reaction at 220°C for 5 h to obtain a gel. The mass fraction of the alumina nano-powder in the mixed solution was 10%, the mass fraction of the aluminum silicate fiber in the mixed solution was 10%, and the mass fraction of the alumina fiber 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.

[0078] The performance test results of the aerogel material prepared by steps (1) to (4) in this example are shown in Table 1.

[0079] Example 6

[0080] Example 6 is basically the same as Example 1, except that:

[0081] (1) The alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid were mixed with water, and uniformly mixed in a high-speed disperser 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°C 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 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 accounted for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0082] In this example, 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.

[0083] Example 7

[0084] Example 7 is basically the same as Example 1, except that:

[0085] (1) The alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid were mixed with water, and uniformly mixed in a high-speed disperser 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 contained in the mixed solution was 25%, 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 accounted for 1.5% of the total weight of the mixed solution, and the concentration of the hydrochloric acid was 2 mol / L.

[0086] The performance test results of the aerogel material prepared by steps (1) to (4) in this example are shown in Table 1.

[0087] The aerogel material prepared by steps (1) to (4) in this example has very good structural strength, but the specific surface area of the material is very small, and the thermal conductivity coefficient is significantly increased.

[0088] Example 8

[0089] Example 8 is basically the same as Example 1, except that:

[0090] (1) mixing alumina nanopowder, aluminum silicate fiber, alumina fiber and hydrochloric acid with water, uniformly mixing 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 5h to obtain a gel; the mass fraction of the alumina nanopowder contained in the mixed solution is 4%, the mass fraction of the aluminum silicate fiber contained in the mixed solution is 2%, and the mass fraction of the alumina fiber 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.

[0091] The performance test results of the aerogel material prepared through steps (1) to (4) of the example are shown in Table 1.

[0092] Example 9

[0093] Example 9 is basically the same as Example 1, except that:

[0094] (4) heat treating 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 1h, and the heat treatment is carried out in an air atmosphere.

[0095] The performance test results of the aerogel material prepared through steps (1) to (4) of the example are shown in Table 1.

[0096] Comparative Example 1

[0097] Comparative Example 1 is basically the same as Example 1, except that:

[0098] (2) aging the obtained gel in a non-sealed environment in air at 60℃ for 2h to obtain an aged gel block; using the aged gel block to carry out subsequent steps (3) and (4).

[0099] The performance test results of the aerogel material prepared through steps (1) to (4) of the example are shown in Table 1.

[0100] Comparative Example 2

[0101] Comparative Example 2 is basically the same as Example 1, except that:

[0102] (1) Al2O3 nano powder, mullite fiber, basalt fiber and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed disperser 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 Al2O3 nano powder contained in the mixed solution was 10%, the mass fraction of mullite fiber contained in the mixed solution was 2%, and the mass fraction of basalt fiber contained in the mixed solution was 1%; 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.

[0103] The performance test results of the aerogel material prepared by steps (1) to (4) of the comparative example are shown in Table 1.

[0104] Comparative Example 3

[0105] (1) Al2O3 nano powder, mullite fiber, basalt fiber and hydrochloric acid were mixed with water, and the mixture was uniformly dispersed in a high-speed disperser 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 Al2O3 nano powder contained in the mixed solution was 10%, the mass fraction of mullite fiber contained in the mixed solution was 2%, and the mass fraction of basalt fiber contained in the mixed solution was 1%; 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.

[0106] (2) The obtained gel was aged in an unsealed environment at 60℃ for 2h to obtain an aged gel.

[0107] (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.

[0108] (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.

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

[0110] Comparative Example 4

[0111] Comparative Example 4 is basically the same as Example 1, except that:

[0112] (1) mixing alumina nanopowder and hydrochloric acid with water, uniformly mixing 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 nanopowder contained in the mixed solution is 10%, 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.

[0113] The performance test results of the aerogel material prepared through steps (1) to (4) in the present comparative example are shown in Table 1.

[0114]

[0115]

[0116] In Table 1, the symbol “—” indicates that the performance index is not tested.

[0117] The part of the present application not described in detail is the technology known to those skilled in the art.

[0118] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; 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 a high-temperature resistant, high-strength aerogel material, 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. The mixture is then subjected to a hydrothermal reaction at 150~300℃ to obtain a gel. The mass fraction of alumina nanoparticles in the mixture is 5~20%. The sum of the mass fractions of aluminum silicate fibers and aluminum oxide fibers in the mixture is 1~15%. The mass ratio of aluminum silicate fibers to aluminum oxide fibers is (1~3):

1. (2) Soak the gel in water to obtain a 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 subjected to heat treatment to obtain a high-temperature resistant and high-strength aerogel material; the high-temperature resistant and high-strength aerogel material has a cage-like structure surrounded by nanobelts; the heat treatment temperature is 600~800℃ and the heat treatment time is 0.5~2h.

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

1.

3. The preparation method according to claim 1, characterized in that: The hydrothermal reaction time is 1~48h; and / or The soaking time is 6 to 72 hours.

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

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

6. The preparation method according to claim 1, 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.

7. A high-temperature resistant and high-strength aerogel material prepared by any one of claims 1 to 6.

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