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Method for preparing silicon dioxide (SiO2) aerogel with continuous density gradient

A density gradient and aerogel technology, applied in the direction of silica, silicon oxide, etc., can solve problems such as difficulty in application, and achieve the effect of complete molding structure, density distribution, and large density difference

Inactive Publication Date: 2011-04-27
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

High-speed centrifugation uses centrifugal force to produce different concentrations of SiO with different centrifugation positions 2 Sol, and then through gelation and supercritical fluid drying process to synthesize gradient density aerogels, but this method is the same as the temperature gradient synthesis method, the difference in density per unit depth of the obtained airgel is small, and it is difficult to apply in special occasions

Method used

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  • Method for preparing silicon dioxide (SiO2) aerogel with continuous density gradient
  • Method for preparing silicon dioxide (SiO2) aerogel with continuous density gradient
  • Method for preparing silicon dioxide (SiO2) aerogel with continuous density gradient

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Embodiment 1

[0034] (1) A one-step catalytic sol-gel method is adopted, with tetraethyl orthosilicate, absolute ethanol, deionized water, and hydrofluoric acid as raw materials, with volume ratios of 1:1:0.25:0.04 and 1:4:0.25, respectively : 0.07 Configure two sols with different target densities, high and low;

[0035] (2) Self-designed and built density gradient hybrid molding device;

[0036] (3) Slowly add the low target density sol to the high target density sol at a speed of 15rad / min through a peristaltic pump, and keep stirring, and at the same time, slowly add the mixed sol to the molding mold at a speed of 15rad / min with a peristaltic pump, Preparation of continuous density gradient SiO 2 Sol;

[0037] (4) The continuous density gradient SiO 2 The sol was left at 40°C for 1 hour to prepare a continuous density gradient SiO 2 wet gel;

[0038] (5) Soak the above wet gel in ethanol for aging for 72 hours, during which the ethanol was replaced twice, and then put into an autoc...

Embodiment 2

[0040] (1) A one-step catalytic sol-gel method is adopted, with ethyl orthosilicate, absolute ethanol, deionized water, and hydrofluoric acid as raw materials, with a volume ratio of 1:3:0.25:0.06 and 1:6:0.25, respectively : 0.1 Configure two sols with different target densities, high and low;

[0041] (2) Self-built density gradient hybrid molding device;

[0042] (3) Slowly add the low target density sol to the high target density sol through a peristaltic pump at a speed of 5 rad / min, and keep stirring, and at the same time, use a peristaltic pump to slowly add the mixed sol to the forming mold at a speed of 5 rad / min, Preparation of continuous density gradient SiO 2 Sol;

[0043] (4) The continuous density gradient SiO 2 The sol was left to stand at 10°C for 3 hours to prepare a continuous density gradient SiO 2 wet gel;

[0044] (5) Soak the above wet gel in ethanol for aging for 72 hours, during which the ethanol was replaced twice, and then placed in an autoclave ...

Embodiment 3

[0046] (1) A one-step catalytic sol-gel method is adopted, with ethyl orthosilicate, absolute ethanol, deionized water, and hydrofluoric acid as raw materials, with a volume ratio of 1:1:0.25:0.04 and 1:6:0.25, respectively : 0.1 Configure two sols with different target densities, high and low;

[0047] (2) Self-built density gradient hybrid molding device;

[0048] (3) Slowly add the low target density sol to the high target density sol through a peristaltic pump at a speed of 10rad / min, and keep stirring, and at the same time, use a peristaltic pump to slowly add the mixed sol to the forming mold at a speed of 10rad / min, Preparation of continuous density gradient SiO 2 Sol;

[0049] (4) The continuous density gradient SiO 2 The sol was left at 20°C for 3 hours to prepare a continuous density gradient SiO 2 wet gel;

[0050] (5) The wet gel was soaked in ethanol for 120 hours and aged for 120 hours, during which the ethanol was replaced twice, and then put into an autocl...

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Abstract

The invention provides a method for preparing silicon dioxide (SiO2) aerogel with continuous density gradient. The method comprises the following steps of: mixing precursor sol with high target density and precursor sol with low target density continuously by using tetraethoxysilane as an organic silicon source, by adopting a continuous forming process and by automatically designing and constructing a density gradient mixed forming device so as to obtain SiO2 sol with continuous density gradient; standing to gelate; and preparing the SiO2 aerogel with continuous density gradient by an aging replacement process and a supercritical drying process. The physical property of the SiO2 aerogel is in gradient distribution along with the change of density, so the application range is widened. The SiO2 sol with continuous density gradient prepared by the method has the characteristics of large density gradient, complete forming structure, continuous distribution of density, simpleness, convenience and controllability of preparation process and the like, so the SiO2 sol can be applied in the fields of space particle capture for aerospace, research on impact wave characteristics for an inertial confinement fusion test, acoustic resistance anti-gradient matching application, high-resolution Cerenkov detectors, high-vacuum thermal insulation materials and the like.

Description

technical field [0001] The invention belongs to the field of preparation of nanoporous airgel materials, and relates to a continuous density gradient SiO 2 Airgel preparation method. Background technique [0002] Airgel is a new research field that emerged in the 1980s. It is a nanoporous network composed of nanometer-scale ultrafine particles or polymer molecules, and the pores are filled with gaseous dispersion media. Highly dispersed solid three-dimensional nanomaterials, the porosity can reach more than 90%. Because the structural unit of the airgel material belongs to nanoscale, high porosity, large specific surface area, low density, quantum size effect, surface and interface effect, it has new properties different from conventional solid materials, such as Young's mode Low volume and thermal conductivity, low apparent density, small refractive index and strong adsorption performance, etc., can be used in a wide range of fields. Of which SiO 2 The porosity of airge...

Claims

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Application Information

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IPC IPC(8): C01B33/16
Inventor 周斌钟艳红归佳寅杜艾
Owner TONGJI UNIV
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