High-temperature-resistant thermal insulation aerogel and preparation method thereof

Abstract

The application discloses a kind of high-temperature-resistant heat-insulating aerogel and preparation method thereof, belong to aerogel technical field.The preparation method of the high-temperature-resistant heat-insulating aerogel includes the following steps: first, L-phenylalanine and graphene oxide are added to deionized water ultrasonic dispersion, adjust pH, temperature stirring, dialysis cooling, freeze drying to obtain modified graphene oxide;Silicon source, anhydrous ethanol and acid are mixed, stirred at room temperature, to obtain precursor solution;Then, modified graphene oxide is dissolved in anhydrous ethanol, mixed with precursor solution after ultrasonic dispersion, add alkali and continue to stir, to obtain sol;Fiber is pressed into fiber preform;The obtained fiber preform is immersed in sol, vacuum preservation, restore to normal pressure, to obtain fiber and sol composite material;Finally, fiber and sol composite material are aged, dried and sintered to obtain high-temperature-resistant heat-insulating aerogel.

Description

Technical Field

[0001] This invention belongs to the field of aerogel technology, specifically relating to a high-temperature resistant heat-insulating aerogel and its preparation method. Background Technology

[0002] Aerogels are ultralight solid materials with a continuous three-dimensional network structure. Based on differences in their structural composition, they are classified into three main categories: inorganic aerogels, organic aerogels, and carbon aerogels. Aerogels possess properties such as high porosity, high specific surface area, low density, low thermal conductivity, low elastic modulus, strong adsorption, low refractive index, and low acoustic impedance, making them promising for applications in various fields including mechanics, thermal engineering, optics, and acoustics.

[0003] Silica aerogel is one of the more technologically advanced aerogels currently available. Its excellent physicochemical properties and ultra-low thermal conductivity have earned it widespread recognition and praise in the thermal insulation materials industry. However, traditional single-system SiO2 aerogel materials can only withstand temperatures up to 600℃, significantly limiting their application range. Furthermore, due to its porous nature and the presence of numerous hydroxyl groups (-OH) on its surface, silica aerogel is hydrophilic, easily adsorbing water vapor in humid environments, leading to increased thermal conductivity and decreased thermal insulation performance. Therefore, researching aerogel materials with good thermal insulation and high-temperature resistance is a problem that needs to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a high-temperature resistant thermal insulation aerogel and its preparation method to solve the problem of poor thermal insulation performance of aerogels.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a high-temperature resistant thermal insulation aerogel includes the following steps:

[0007] Step 1: Add L-phenylalanine and graphene oxide to deionized water, disperse by ultrasonication, adjust the pH to 10-10.2, stir at 90-95℃, cool and dialyze, and freeze dry to obtain modified graphene oxide.

[0008] Step 2: Mix the silicon source, anhydrous ethanol and acid, and stir at room temperature to obtain a precursor solution; dissolve the modified graphene oxide in anhydrous ethanol, disperse it ultrasonically, mix it with the precursor solution, add alkali and continue stirring to obtain a sol;

[0009] Step 3: Press the fibers into fiber preforms;

[0010] Step 4: Immerse the fiber preform obtained in Step 3 into the sol obtained in Step 2, evacuate to -0.09 to -0.1 MPa, maintain pressure for 2 to 3 hours, and then introduce air to restore to normal pressure to obtain fiber and sol composite material.

[0011] Step 5: Aging, drying, and sintering the fiber-sol composite material to obtain a high-temperature resistant heat-insulating aerogel.

[0012] Furthermore, in step 1, the ratio of L-phenylalanine, graphene oxide, and deionized water is 0.2-0.4 g: 1 g: 100 mL.

[0013] Furthermore, in step 2, the ratio of silicon source, anhydrous ethanol, acid and base is 8-10g:250mL:0.02mL:0.1mL; the ratio of modified graphene oxide and anhydrous ethanol is 0.3-0.5g:100mL.

[0014] Furthermore, graphene oxide was prepared using the Hummers method.

[0015] Furthermore, the silicon source is one of tetraethyl orthosilicate and methyl orthosilicate.

[0016] Furthermore, the acid is one of nitric acid, hydrochloric acid, and sulfuric acid.

[0017] Furthermore, the alkali is ammonia.

[0018] Furthermore, the fiber is one of zirconium oxide fiber, alumina fiber, quartz fiber, and mullite fiber.

[0019] A high-temperature resistant thermal insulation aerogel is prepared by the above steps.

[0020] The beneficial effects of this invention are:

[0021] The high-temperature resistant insulating aerogel of this invention not only has high porosity but also low density and thermal conductivity, with a thermal conductivity of 0.030-0.035 W / (m·K) at 1100℃. Therefore, the aerogel obtained in this invention exhibits excellent thermal insulation performance.

[0022] The high-temperature resistant thermal insulation aerogel provided by this invention uses an organosilicon source as a precursor, adds modified graphene oxide aerogel, and prepares a modified sol using an acid-base two-step catalytic method. The modified silica sol is then impregnated into a fiber preform under vacuum pressure to obtain a fiber-sol composite material. After gel aging, drying, and sintering, the high-temperature resistant thermal insulation aerogel is finally obtained. The preparation method is simple, low-cost, and suitable for large-scale industrial production.

[0023] The modified graphene oxide prepared in this invention is first obtained using the Hummers method to obtain graphene oxide with a high specific surface area. Then, using L-phenylalanine as a hydrophobic modifier, a graphene oxide aerogel with high hydrophobic properties is prepared. After mixing with a solution using an organosilicon source as a precursor, it can provide support, significantly enhancing the stability and mechanical strength of the aerogel structure. Furthermore, the addition of highly hydrophobic graphene oxide aerogel can improve the hydrophobicity of the sol system, further enhancing the thermal insulation performance of the aerogel. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] The graphene oxide used in this invention is prepared by the Hummers method, and the preparation steps are as follows:

[0026] 0.3 g of graphene was added to 2.4 mL of concentrated sulfuric acid and stirred for 0.5 h. Then, 0.5 g of sodium nitrate was added, the temperature was raised to 80 °C, and stirring was continued for 5 h. 12 mL of concentrated sulfuric acid was added, and the temperature was controlled below 5 °C. 1.5 g of potassium permanganate was slowly added, the temperature was raised to 35 °C, and stirring was continued for 2 h. Then, 70 mL of deionized water and 2 mL of H2O2 (mass fraction 30%) were added. The mixture was centrifuged and washed successively with 5% HCl and deionized water until the pH reached 7. Finally, it was dried at 60 °C for 65 h to obtain graphene oxide.

[0027] Example 1

[0028] This embodiment provides a method for preparing high-temperature resistant thermal insulation aerogel, including the following steps:

[0029] Step 1: Add 0.2g L-phenylalanine and 1g graphene oxide to 100mL of deionized water, disperse by ultrasonication, adjust the pH to 10, stir at 90℃, cool and dialyze, and freeze dry to obtain modified graphene oxide.

[0030] Step 2: Mix 9g of tetraethyl orthosilicate, 250mL of anhydrous ethanol and 0.02mL of nitric acid, and stir at room temperature to obtain a precursor solution; dissolve 0.3g of modified graphene oxide in 100mL of anhydrous ethanol, disperse by ultrasonication, mix with the precursor solution, add 0.1mL of ammonia (concentration of 0.5mol / L) and continue stirring to obtain a sol;

[0031] Step 3: Press the zirconium oxide fibers into fiber preforms;

[0032] Step 4: Immerse the fiber preform obtained in Step 3 into the sol obtained in Step 2, evacuate to -0.09MPa, maintain pressure for 3 hours, and then introduce air to restore to normal pressure to obtain the fiber-sol composite material.

[0033] Step 5: Aging, drying, and sintering the fiber-sol composite material to obtain a high-temperature resistant heat-insulating aerogel.

[0034] Example 2

[0035] The only difference from Example 1 is that:

[0036] Step 1: Add 0.4g L-phenylalanine and 1g graphene oxide to 100mL of deionized water, disperse by ultrasonication, adjust the pH to 10.2, stir at 95℃, cool and dialyze, and freeze dry to obtain modified graphene oxide.

[0037] The remaining raw materials and steps are the same as in Example 1.

[0038] Example 3

[0039] The only difference from Example 1 is that:

[0040] Step 2: Mix 8g of methyl orthosilicate, 250mL of anhydrous ethanol and 0.02mL of hydrochloric acid, and stir at room temperature to obtain a precursor solution; dissolve 0.4g of modified graphene oxide in 100mL of anhydrous ethanol, disperse by ultrasonication, mix with the precursor solution, add 0.1mL of ammonia (concentration of 0.5mol / L) and continue stirring to obtain a sol;

[0041] The remaining raw materials and steps are the same as in Example 1.

[0042] Example 4

[0043] The only difference from Example 1 is that:

[0044] Step 2: Mix 10g of methyl orthosilicate, 250mL of anhydrous ethanol and 0.02mL of sulfuric acid, and stir at room temperature to obtain a precursor solution; dissolve 0.5g of modified graphene oxide in 100mL of anhydrous ethanol, disperse by ultrasonication, mix with the precursor solution, add 0.1mL of ammonia (concentration of 0.5mol / L) and continue stirring to obtain a sol;

[0045] The remaining raw materials and steps are the same as in Example 1.

[0046] Example 5

[0047] The only difference from Example 1 is that:

[0048] Step 4: Immerse the fiber preform obtained in Step 3 into the sol obtained in Step 2, evacuate to -0.1MPa, maintain pressure for 2 hours, and then introduce air to restore to normal pressure to obtain the fiber-sol composite material.

[0049] The remaining raw materials and steps are the same as in Example 1.

[0050] Comparative Example 1

[0051] This comparative example provides a method for preparing a high-temperature resistant thermal insulation aerogel, including the following steps:

[0052] Step 1: Mix 9g of tetraethyl orthosilicate, 250mL of anhydrous ethanol and 0.02mL of nitric acid, stir at room temperature to obtain a precursor solution, add 0.1mL of ammonia (concentration of 0.5mol / L) and continue stirring to obtain a sol;

[0053] Step 2: Press the zirconium oxide fibers into fiber preforms;

[0054] Step 3: Immerse the fiber preform obtained in Step 2 into the sol obtained in Step 1, evacuate to -0.09MPa, maintain pressure for 3 hours, and then introduce air to restore to normal pressure to obtain the fiber-sol composite material.

[0055] Step 4: Aging, drying, and sintering the fiber-sol composite material to obtain high-temperature resistant heat-insulating aerogel.

[0056] Comparative Example 2

[0057] Compared with Example 1, 0.3g of modified graphene oxide in step 2 was replaced with 0.25g of modified graphene oxide; the remaining raw materials and steps were the same as in Example 1.

[0058] Comparative Example 3

[0059] Compared with Example 4, 0.5g of modified graphene oxide in step 2 was replaced with 0.55g of modified graphene oxide; the remaining raw materials and steps were the same as in Example 4.

[0060] The high-temperature resistant thermal insulation aerogels obtained in Examples 1-5 and Comparative Examples 1-3 were tested. Porosity was determined using the direct mass-volume calculation method, where the porosity (%) was determined by the ratio of the sample bulk density to the density of the corresponding dense solid material. The test was repeated five times, and the average value was taken as the final measurement result. The compressive strength of the aerogels was tested using an Instron ElectroPlus electronic dynamic and static universal testing machine according to GB / T1449-2005. The results are shown in Table 1.

[0061] Table 1

[0062]

[0063] As shown in Table 1, compared with Comparative Examples 1-3, the high-temperature resistant and heat-insulating aerogels obtained in Examples 1-5 all have high porosity and low density and thermal conductivity. No modified graphene oxide was added in Comparative Example 1, while the amount of graphene oxide added in Comparative Examples 2-3 all exceeded the range defined in this invention. Therefore, it is evident that whether or not modified magnesium hydroxide is used and its dosage range both affect the porosity, thermal conductivity, density, and compressive strength of the obtained aerogel.

[0064] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0065] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-temperature resistant thermal insulation aerogel, characterized in that, Includes the following steps: Step 1: Add L-phenylalanine and graphene oxide to deionized water, disperse by ultrasonication, adjust the pH to 10-10.2, stir at 90-95℃, cool and dialyze, and freeze-dry to obtain modified graphene oxide; the ratio of L-phenylalanine, graphene oxide and deionized water in Step 1 is 0.2-0.4g:1g:100mL; Step 2: Mix the silicon source, anhydrous ethanol and acid, and stir at room temperature to obtain a precursor solution; dissolve the modified graphene oxide obtained in step 1 in anhydrous ethanol, disperse it by ultrasonication, mix it with the precursor solution, add alkali and continue stirring to obtain a sol. Step 3: Press the zirconium oxide fibers into fiber preforms; Step 4: Immerse the fiber preform obtained in Step 3 into the sol obtained in Step 2, evacuate to -0.09 to -0.1 MPa, maintain pressure for 2 to 3 hours, and then introduce air to restore to normal pressure to obtain fiber and sol composite material. Step 5: Aging, drying, and sintering the fiber-sol composite material to obtain a high-temperature resistant heat-insulating aerogel.

2. The method for preparing a high-temperature resistant thermal insulation aerogel according to claim 1, characterized in that, In step 2, the ratio of silicon source, anhydrous ethanol, acid and base is 8-10g:250mL:0.02mL:0.1mL; the ratio of modified graphene oxide and anhydrous ethanol is 0.3-0.5g:100mL.

3. The method for preparing a high-temperature resistant thermal insulation aerogel according to claim 1, characterized in that, Graphene oxide is prepared using the Hummers method.

4. The method for preparing a high-temperature resistant thermal insulation aerogel according to claim 1, characterized in that, The silicon source is one of tetraethyl orthosilicate and methyl orthosilicate.

5. The method for preparing a high-temperature resistant thermal insulation aerogel according to claim 1, characterized in that, The acid is one of nitric acid, hydrochloric acid, and sulfuric acid.

6. The method for preparing a high-temperature resistant thermal insulation aerogel according to claim 1, characterized in that, The alkali is ammonia.

7. A high-temperature resistant thermal insulation aerogel, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

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