Method for preparing high-strength, low-density silicon dioxide aerogel

A silica and low-density technology, applied in the field of inorganic porous materials, can solve the problems of insignificant improvement of material strength, cumbersome solvent exchange process, and reduction of material porosity, so as to shorten the aging cycle, increase material strength, and improve material strength Effect

Inactive Publication Date: 2011-01-19
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] However, these methods have brought a series of problems while improving the strength of the material, or the porosity of the material is reduced, or the strength of the material is not significantly improved, or a long aging work period is required, or a tedious process is required. Solvent exchange process, etc.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] Orthomethyl silicate (TMOS): the molar ratio of deionized water: absolute ethanol: sulfuric acid is 1: 2.6: 5.8: 3.05×10 -4 . Mix TMOS, deionized water, absolute ethanol and 0.35 mol / l sulfuric acid evenly, place in a water bath at 80° C., and keep warm for 1 hour for hydrolysis. Then ammonia water (1.0wt.%) was added dropwise and stirred, and the pH at this time was ≈8. It is then poured into a mold and left to stand in the air at room temperature to form a gel. After soaking in absolute ethanol for 24 hours (at this time, the room temperature is 20°C), demould, take out the wet gel, and put it into a container containing 10vol.% TMOS, 89vol.% absolute ethanol, 0.5vol.% deionized water and 0.5 vol.% ammonia water (1.0wt.%) in a high-pressure tank, and then aged at 80°C for 10 days. followed by supercritical CO 2 Drying (temperature: 45° C., pressure: 12 MPa) is sufficient.

[0018] The bulk density of the obtained sample is 0.23g / cm 3 . The sample size for the c...

Embodiment 2

[0020] Orthomethyl silicate (TMOS): the molar ratio of deionized water: absolute ethanol: hydrochloric acid is 1: 2.6: 5.8: 6.1 × 10 -4 . After mixing TMOS, deionized water, absolute ethanol and 0.35 mol / l hydrochloric acid evenly, put it in a water bath at 60°C and keep it warm for 2 hours for hydrolysis. Then ammonia water (1.5wt.%) was added dropwise and stirred, and the pH at this time was ≈8. It is then poured into a mold and left to stand in the air at room temperature to form a gel. After soaking in absolute ethanol for 24 hours (at this time, the room temperature is 20°C), demould, take out the wet gel, and put it into a container containing 20vol.% TMOS, 79vol.% absolute ethanol, 0.5vol.% deionized water and 0.5 vol.% ammonia water (1.5wt.%) in a high-pressure tank, and then aged at 150°C for 3 days. After that, it can be dried under normal temperature and pressure (temperature: 20° C.).

[0021] The bulk density of the obtained sample is 0.26g / cm 3 . The sample...

Embodiment 3

[0023] Orthoethyl silicate (TEOS): the molar ratio of deionized water: absolute ethanol: sulfuric acid is 1: 8.0: 4.5: 4.2×10 -4. After mixing TEOS, deionized water, absolute ethanol and 0.35mol / l sulfuric acid evenly, put it in a water bath at 80°C and keep it warm for 1.5h for hydrolysis. Then ammonia water (1.0wt.%) was added dropwise and stirred, and the pH at this time was ≈8. It is then poured into a mold and left to stand in the air at room temperature to form a gel. After soaking in absolute ethanol for 36 hours (at this time, the room temperature is 15°C), 89vol.% of the mold is removed, and the wet gel is taken out and placed in a container containing 10vol.% TEOS, 89vol.% absolute ethanol, and 0.5vol.% deionized water and 0.5vol.% ammonia (1.0wt.%) in a high-pressure tank, and then aged at 90°C for 8 days. Then dry at normal temperature and pressure (temperature: 15°C).

[0024] The bulk density of the obtained sample is 0.25g / cm 3 . The sample size for the co...

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Abstract

The invention discloses a new preparation method for silicon dioxide gas gel with high intensity and low density, belonging to inorganic porous material technical field. The concrete preparation procedures comprise: hydrolyzing orthosilicate methyl ester or orthosilicate methyl ester for two to six hours under the pH value between one point five and four point five at the temperature between fifty to eighty DEG C, adding ammonia in drops, then injecting into a mold to form a wet gel monomer in the air, putting the wet gel obtained to a pressure tank, aging for three to ten days in the aging liquid with a certain ratio at the temperature between eighty DEG C to one hundred and fifty DEG C, then obtaining the silicon dioxide gas gel setting material with high intensity and low density through drying. The new preparation method for silicon dioxide gas gel with high intensity and low density has the advantages of having easy operation and simple technology, increasing the intensity of traditional silicon dioxide gas gel material, simultaneously ensuring low density, and promoting the application of silicon dioxide gas gel in setting and insulation product field.

Description

technical field [0001] The invention belongs to the technical field of inorganic porous materials, and proposes a method for preparing high-strength and low-density silica airgel. Background technique [0002] With the development of social economy and the improvement of human living standards, the demand for energy is increasing, and traditional mineral resources such as coal, oil, and natural gas will face depletion in the near future. In order to alleviate the energy crisis, in addition to the development, research and utilization of new energy sources such as solar energy, saving energy and reducing energy loss is also an important aspect. Therefore, it is very necessary to research and develop porous materials with excellent thermal insulation properties. [0003] Silica airgel is a special nanoporous material with a large specific surface area (800-1000m 2 / g), low density (0.002~0.8g / cm 3 ), chemical inertness and many other excellent properties, especially its hig...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B33/14C01B33/158
Inventor 赵海雷何方张翠娟曲选辉高峰李雪
Owner UNIV OF SCI & TECH BEIJING
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