High-entropy thermal insulation aerogel material and preparation method thereof

Abstract

The application provides a high-entropy thermal insulation aerogel material and a preparation method thereof, and oxygen-containing functional groups on the surface of graphene oxide are used as chelating sites of multi-component metal ions, a three-dimensional network of graphene aerogel is used as a skeleton, and a layered structure induction effect of two-dimensional graphene sheets on growth of high-entropy metal crystals is combined to prepare a high-entropy aerogel material with a continuous network, in which two-dimensional layered high-entropy metal oxide crystals are connected in the pore wall. The high-entropy aerogel prepared by the scheme has low thermal conductivity and low density, has good compression elasticity in room temperature and high-temperature air environments, and has significantly better thermal insulation performance than corresponding single-component oxide aerogel materials, and has a good application prospect in the fields of thermal insulation and high-temperature heat protection.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, specifically relating to a high-entropy thermal insulation aerogel material and its preparation method. Background Technology

[0002] High-performance thermal insulation materials are key components for thermal protection in aerospace, industrial storage tanks, pipelines, and military fields, and are also crucial materials for energy-efficient buildings and rail transportation. Aerogel materials, with their unique high-porosity structure, effectively reduce solid-state heat conduction. Furthermore, their low density, high specific surface area, and thermal stability make them an excellent thermal insulation material.

[0003] However, traditional polymeric insulating aerogels such as polystyrene foam, polyurethane foam, and rock wool can only be used at room temperature. Ceramic insulating aerogels, on the other hand, can exhibit excellent insulating performance over a certain wide temperature range.

[0004] For example, silica aerogel can be used from room temperature to 600°C. However, it is generally prepared by organic precursors through sol-gel method combined with supercritical drying. The preparation process is complicated, has only a single component, and the prepared silica nanoparticles are connected by a beaded structure with poor mechanical compressibility. The structure collapses in environments above 600°C, which cannot meet the growing demand for high-temperature insulation.

[0005] In recent years, entropy-stabilized oxide materials have gradually emerged. High-entropy ceramics typically contain five or more ceramic powder components with similar content, resulting in high configurational entropy. The lattice distortion caused by the entropy effect can reduce the thermal conductivity of the ceramics. They also possess higher strength, modulus, and hardness than traditional ceramics, along with strong covalent bonding and a high melting point, making them suitable for various extreme service environments and representing an important development direction for next-generation thermal structural materials. For high-entropy alloys, the greater the difference in atomic radius, the more severe the lattice distortion, thus increasing the refractive index for phonons and further improving thermal insulation performance. However, based on the Hume-Rothery rule, when the atomic size difference is too large, direct alloying and the corresponding macroscopic material preparation are very difficult due to the positive heat of reaction. Such high-entropy compositions are more prone to phase separation, making it difficult to utilize the lattice distortion effect of solid solution alloys, thereby affecting thermal insulation performance. Summary of the Invention

[0006] To address the aforementioned technical deficiencies, this invention proposes a method for preparing high-entropy thermal insulation aerogels, successfully producing high-entropy oxide aerogels composed of mutually insoluble elements with significantly different atomic radii.

[0007] The application uses graphene aerogel three-dimensional network skeleton as a sacrificial template, uses the template induction effect of two-dimensional graphene sheet layer on high-entropy metal oxide crystal growth, and prepares graphene aerogel material with a continuous network formed by two-dimensional layered mesoporous high-entropy metal oxide lap joints, so that the prepared high-entropy thermal insulation aerogel has good thermal insulation performance at room temperature and high temperature.

[0008] One of the technical solutions of the application is to provide a preparation method of high-entropy thermal insulation aerogel, which comprises the following steps:

[0009] (1) coating and drying an oxidized graphene dispersion liquid into a film to obtain an oxidized graphene film;

[0010] (2) soaking the obtained film in an aqueous solution of a multi-metal inorganic salt for 4-12 hours, and drying to obtain a multi-metal ion hybrid film; the multi-metal salt comprises two or more mutually insoluble metal elements, such as zirconium and lanthanum, copper and tantalum, molybdenum and silver, molybdenum and copper, niobium and copper, copper and tungsten, zirconium and copper, copper and iron, copper and cobalt, copper and hafnium, etc.

[0011] (3) foaming the obtained multi-metal ion hybrid film in a foaming agent, and drying to obtain a multi-metal ion hybrid aerogel;

[0012] (4) heat-treating the obtained multi-metal ion hybrid aerogel in an inert gas to obtain a high-entropy metal oxide and graphene composite aerogel, and then heat-treating the composite aerogel in air to remove the graphene template, thereby obtaining a high-entropy metal oxide aerogel.

[0013] Further, the thickness of the graphene oxide film in step 1 is 10-100 μm.

[0014] Further, the multi-metal inorganic salt in step 2 comprises all metal inorganic salts, and the concentration of the aqueous solution is not less than 10wt%.

[0015] Further, the foaming agent in step 3 is one of a hydrazine hydrate solution, a sodium borohydride solution, a sodium bicarbonate solution and a sodium carbonate solution.

[0016] Further, the heat treatment in the inert gas in step 4 is 1200℃ for 2-4 hours in the inert gas, and the heat treatment in air in step 4 is 600℃ for 1-2 hours in air.

[0017] The high-entropy oxide aerogel prepared by the scheme has low thermal conductivity, low density, good compression elasticity in room temperature and high-temperature air environment, high elasticity and stable existence in high-temperature air, and the heat insulation performance is significantly better than that of the corresponding single-component oxide aerogel material, and has a good application prospect in the fields of heat preservation and heat insulation and high-temperature resistance.

[0018] The second technical scheme of the present application provides a high-entropy heat insulation aerogel prepared by the above method, wherein the high-entropy heat insulation aerogel has a spherical microporous structure, and the pore wall is overlapped by two-dimensional layered mesoporous high-entropy metal oxide.

[0019] The introduction of the high-entropy effect in the aerogel causes serious distortion in the lattice structure and a large number of crystal boundaries, which causes a large number of phonon scattering, and by changing different metal ions in the high-entropy ceramic, preferably elements with large differences in atomic radius and atomic mass, the mass field disturbance of phonon scattering in the high-entropy ceramic can be increased, thereby hindering the transmission of phonons, and the thermal conductivity of the solid heat conduction ceramic in the aerogel wall can be effectively reduced.

[0020] In addition, the two-dimensional high-entropy metal oxide sheet layer surface contains a large number of mesopores, which can further reduce the average free path of phonons and gas heat conduction. And the high-entropy ceramic grown on the spherical curved surface will introduce a large curvature stress field to the high-entropy crystal, thereby increasing the stress field disturbance of phonon scattering in the high-entropy ceramic, further hindering the transmission of phonons, and reducing the thermal conductivity of the high-entropy ceramic.

[0021] The third technical scheme of the present application provides the heat insulation application of the above high-entropy heat insulation aerogel.

[0022] The present application has the following beneficial effects:

[0023] (1) The problem that high-entropy composition is prone to phase separation when the atomic size difference is too large and it is difficult to play the solid solution lattice distortion effect is solved.

[0024] (2) A high-entropy oxide aerogel composed of elements with large differences in atomic radius and not mutually soluble is successfully prepared by anchoring a variety of metal inorganic salt ions on two-dimensional graphene oxide sheets through a simple solution immersion method.

[0025] (3) The obtained high-entropy aerogel material has good heat insulation effect in room temperature and high-temperature air environment, and its thermal conductivity is as low as 11 m W / (m•K) at room temperature, and based on the oxidation resistance of the oxide ceramic, the thermal conductivity of the prepared high-entropy aerogel is as low as 40 m W / (m•K) at 1000 DEG C high-temperature environment.

[0026] (4) The obtained high-entropy aerogel material has good compression resilience in room temperature and high-temperature air environment. The spherical microporous structure and two-dimensional nanoscale thin wall serve as an elastic template, and the strengthening effect of high-entropy crystals in the aerogel wall is combined, so that the ability of the aerogel pore wall to resist deformation is improved, the structure is prevented from being damaged under high-temperature thermal stress, and the high-entropy aerogel realizes the characteristics of high elasticity at high temperature. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 SEM image of high-entropy metal oxide aerogel.

[0028] Figure 2 Elemental distribution EDS image of high-entropy metal oxide aerogel. DETAILED DESCRIPTION

[0029] The following examples are intended to further illustrate the present application and are not intended to limit the scope of the present application. Unless otherwise indicated, parts by weight and percentages by weight are used herein.

[0030] The raw materials used in the present application are all conventional commercially available products unless otherwise specified; the methods used in the present application are all conventional methods in the art unless otherwise specified.

[0031] The following examples are intended to further illustrate the present application and are not intended to limit the scope of the present application. Unless otherwise indicated, parts by weight and percentages by weight are used herein.

[0032] It should be clear that the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0033] The terms used in the embodiments of the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the present application. The singular forms "a", "an" and "the" used in the embodiments of the present application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0034] The mesopores in the present application are pores with a pore size of 2-50 nm.

[0035] Example 1

[0036] The concentration of the solution is 10 mg / cm 3A graphene oxide solution (purchased from Hangzhou Gaoxi Technology Co., Ltd.) was coated and dried into a 10 μm thick film. This film was then immersed in a salt solution containing copper, tungsten, molybdenum, tantalum, and niobium metal cations in an equimolar ratio (40 wt%) for 4 hours. After drying, it was foamed in a 30% hydrazine hydrate solution for 1 hour to obtain a graphene oxide aerogel with an internal spherical continuous microporous curved network structure. The aerogel was then heat-treated in an inert gas atmosphere at 1200℃ for 2 hours to obtain a high-entropy metal oxide graphene composite aerogel. This aerogel was then heat-treated in air at 600℃ for 1 hour to remove the graphene template, yielding a high-entropy solid solution metal oxide aerogel. The density of this aerogel was 16 mg / cm³. 3 It has a thermal conductivity of 15 m W / (m•K) at room temperature and 55 m W / (m•K) in air at 1000℃. After being compressed 100 times with a deformation of 60% in air at 1000℃, its elastic recovery rate reaches 80%.

[0037] Example 2

[0038] A concentration of 10 mg / cm 3 A graphene oxide solution (purchased from Hangzhou Gaoxi Technology Co., Ltd.) was coated and dried into a 100 μm thick film. This film was then immersed in a salt solution containing copper, chromium, niobium, iron, and platinum metal cations in an equimolar ratio (50 wt%) for 4 hours. After drying, it was placed in a 30% sodium carbonate solution for 1 hour to foam, resulting in a graphene oxide aerogel with an internal spherical continuous microporous curved network structure. The aerogel was then heat-treated at 1200℃ in an inert gas atmosphere for 4 hours to obtain a high-entropy metal oxide graphene composite aerogel. This aerogel was then heat-treated in air at 600℃ for 2 hours to remove the graphene template, yielding a high-entropy solid solution metal oxide aerogel. The density of this aerogel was 18 mg / cm³. 3 It has a thermal conductivity of 16 m W / (m•K) at room temperature and 60 m W / (m•K) in air at 1000℃. After being compressed 100 times with 60% deformation in air at 1000℃, its elastic recovery rate reaches 78%.

[0039] Example 3

[0040] A concentration of 10 mg / cm 3mg / cm3, the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air. 3 , the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air.

[0041] Example 4

[0042] mg / cm3, the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air. 3 mg / cm3, the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air. Figure 2 mg / cm3, the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air. 3 , the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air.

[0043] Comparative Example 1

[0044] mg / cm3, the thermal conductivity is 11 m W / (m•K) at room temperature, and 40 m W / (m•K) at 1000℃ in air. The elastic recovery rate is 86% after 100 cycles of compression at 60% deformation at 1000℃ in air. 3The graphene oxide solution (purchased from Hangzhou Gaoene Technology Co., Ltd.) was scraped and dried into a 10-micron-thick film, then immersed in a salt solution containing only zirconium ions, with a solution concentration of 60wt%, for 4h, and then placed in a 30% hydrazine hydrate solution for 1h to obtain a graphene oxide aerogel with a spherical continuous microporous curved surface network structure. After the above aerogel was heat-treated in an inert gas at 1200℃ for 3h, a zirconium oxide graphene composite aerogel was obtained, and then after the graphene template was removed by heat-treatment in air at 600℃ for 1h, a zirconium oxide aerogel was obtained. The density of the aerogel was 13 mg / cm 3 The thermal conductivity at room temperature was 26 m W / (m•K), and the thermal conductivity in air at 1000℃ was 120 mW / (m•K). After 60% deformation in air at 1000℃ for 100 cycles, the elastic recovery rate was 30%.

[0045] Comparative Example 2

[0046] A graphene oxide solution with a concentration of 10mg / cm 3 The graphene oxide solution (purchased from Hangzhou Gaoene Technology Co., Ltd.) was scraped and dried into a 10-micron-thick film, then immersed in a salt solution containing zirconium, titanium, tantalum, niobium, and hafnium metal cations, with a solution concentration of 5wt%, for 4h, and then placed in a 30% hydrazine hydrate solution for 1h to obtain a graphene oxide aerogel with a spherical continuous microporous curved surface network structure. After the above aerogel was heat-treated in an inert gas at 1200℃ for 2h, a high-entropy metal oxide graphene composite aerogel was obtained, and then after the graphene template was removed by heat-treatment in air at 600℃ for 1h, the structure collapsed, and due to the low content of oxides, the macroscopic body structure of the aerogel could not be obtained.

[0047] Comparative Example 3

[0048] Nickel, zirconium, chromium, manganese, iron, cobalt, hafnium, copper, zinc, and praseodymium metal particles were mixed in an equimolar ratio, and a bulk body was prepared by high-pressure high-temperature sintering. The obtained bulk body had a phase separation crystal structure.

[0049] The above examples illustrate the structure, features, and effects of the present application. The above description is only a preferred embodiment of the present application. Any changes or modifications made in accordance with the concept of the present application, or equivalent embodiments with equivalent changes, are still within the scope of the present application.

Claims

1. A method for preparing a high-entropy thermal insulation aerogel, characterized in that, The method comprises the following steps: (1) coating and drying a graphene oxide dispersion to obtain a graphene oxide film; (2) soaking the obtained film in an aqueous solution of a multi-metal inorganic salt for 4-12 hours, and drying to obtain a multi-metal ion hybrid film; the multi-metal salt comprises two or more mutually insoluble metal elements; (3) foaming the obtained multi-metal ion hybrid film in a foaming agent, and drying to obtain a multi-metal ion hybrid aerogel; (4) heat-treating the obtained multi-metal ion hybrid aerogel in an inert gas to obtain a high-entropy metal oxide and graphene composite aerogel, and then heat-treating the composite aerogel in air to remove the graphene template, thereby obtaining a high-entropy metal oxide aerogel.

2. The production method according to claim 1, characterized by, The graphene oxide film in step 1 has a thickness of 10-100 μm.

3. The preparation method according to claim 1, characterized in that, The multi-metal inorganic salt in step 2 comprises five or more metal inorganic salts, and the aqueous solution has a concentration of no less than 10 wt%.

4. The method of claim 1, wherein, The foaming agent in step 3 is one of a hydrazine hydrate solution, a sodium borohydride solution, a sodium bicarbonate solution, and a sodium carbonate solution, and has a concentration of 30% and a foaming time of 1 h.

5. The preparation method according to claim 1, characterized in that, The heat treatment in the inert gas in step 4 is heat treatment at 1200℃ for 2-4 hours in an inert gas, and the heat treatment in air in step 4 is heat treatment at 600℃ for 1-2 hours in air.

6. A high-entropy thermal insulation aerogel prepared by the preparation method in claim 1.

7. The high-entropy thermal insulation aerogel of claim 6, wherein, The pore wall is composed of two-dimensional sheet-shaped mesoporous high-entropy metal oxide crystals.

8. A thermal insulation application of the high-entropy thermal insulation aerogel in claim 1.

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