Preparation method of silicon carbide aerogel on basis of SiO2 aerogel as template

An aerogel, silicon carbide technology, applied in silicon carbide, carbide and other directions, can solve the problems of difficult mass production, high cost, and difficulty in obtaining raw materials

Inactive Publication Date: 2014-06-18
HENAN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

(Nicholas Leventis , Anand Sadekar, Naveen Chandrasekaran, and Chariklia Sotiriou-Leventis, Click Synthesis of Monolithic Silicon Carbide Aerogels from Polyacrylonitrile-Coated 3D Silica Networks, Chem. Mater. 2010, 22, 2790–2803) However, the problem with this method is The raw materials are difficult to obtain, the cost is high, and it is difficult to produce on a large scale

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0015] (1) Preparation of silica sol: Calculate the molar ratio of ethyl orthosilicate (TEOS), absolute ethanol, and distilled water at a ratio of 1:4:4. The masses are 208 grams, 184 grams, 72 grams respectively, 4 milliliters of nitric acid (mass percentage concentration is 63%), and the prepared mixed solution is bathed in water at 70°C for 2 hours;

[0016] (2) Preparation of silica airgel: use alkaline conditions, use 2% concentration of ammonia water, the dosage is 3.1 grams, and the molar ratio of tetraethyl orthosilicate (TEOS), absolute ethanol, distilled water, and ammonia water is 1:4 :4:3.6×10 -3 , when adding ammonia water, stir the silica sol, then place it to be gelled, age the obtained gel for three days, perform solvent exchange with ethanol three times, with an interval of 12 hours each time, and then dry it with supercritical carbon dioxide to obtain silica airgel ;

[0017] (3) Infiltrate the prepared silica airgel with polycarbosilane (molecular weight: ...

example 2

[0022] (1) Preparation of silica sol: Calculate the molar ratio of ethyl orthosilicate (TEOS), absolute ethanol, and distilled water at a ratio of 1:4:4. The masses are 104 grams, 92 grams, 36 grams respectively, 2 milliliters of nitric acid (mass percentage concentration is 63%), and the silica sol is obtained in a water bath at 60°C for 2 hours;

[0023] (2) Preparation of silica composite airgel: add nano-acetylene black to the prepared silica sol, 30 grams of particle size less than 10 nanometers, 0.2 grams of ferric oxide; then use 2% ammonia water as gelling agent, The dosage is 2.0 grams, the silica sol is stirred, and then the gel is left to stand; the resulting gel is aged for four days, and the water in the gel is exchanged with ethanol for three times, with an interval of 16 hours each time, and then dried with supercritical carbon dioxide;

[0024] (3) Put the obtained silica airgel composite material into a vacuum graphite container for reaction, and the pressure ...

example 3

[0028] (1) Preparation of silica sol: Calculate the molar ratio of ethyl orthosilicate (TEOS), absolute ethanol, and distilled water at a ratio of 1:4:4. The masses are 104 grams, 92 grams, 36 grams respectively, 2 milliliters of nitric acid (63% by mass percentage concentration), and the prepared solutions are placed in a water bath at 60°C for 3 hours;

[0029](2) Preparation of silica composite airgel: add nano-acetylene black to the prepared silica sol, 25 grams of particle size less than 10 nanometers and 20 grams of silicon powder less than 10 nanometers, 0.1 grams of ferric oxide, chlorine Sodium chloride 0.1 g, after stirring the added substances evenly, gel with 2% concentration of ammonia water, the dosage is 2.0 g, then continue to stir the silica sol, and then place it to wait for the gel; age the obtained gel for three days, and use n-hexane Exchange the water in the gel, three times, each time for 8 hours, and then dry it with supercritical carbon dioxide;

[00...

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Abstract

The invention discloses a preparation method of a silicon carbide aerogel on the basis of a SiO2 aerogel as a template. The method is characterized in that the method comprises the following steps: preparing the SiO2 aerogel, adding a carbon material or a carbonaceous compound into the pores of the SiO2 aerogel, preparing and preparing a silicon carbide aerogel through a carbon thermal reduction process, or adding the prepared SiO2 aerogel into the carbon material to prepare a SiO2 aerogel composite material, and preparing the silicon carbide aerogel through carbon thermal reduction; removing residual impurities in the silicon carbide aerogel by using a nitric acid and sulfuric acid mixed liquid; and removing superfluous SiO2 by using sodium hydroxide, and removing silicon by using hydrofluoric acid.

Description

technical field [0001] The invention relates to a silicon carbide airgel prepared by using silicon dioxide airgel as a template, which is a nanoporous material with high porosity, which not only has the characteristics of silicon carbide material, but also has the characteristics of airgel material; carbonization Silica airgel has the characteristics of low density, high porosity, high strength, corrosion resistance, high temperature resistance, etc., and is widely used in various fields such as high temperature gas purifiers, diesel engine exhaust processors, sensors, heat exchangers, and catalyst carriers. Background technique [0002] Silicon carbide materials have the characteristics of high temperature resistance, oxidation resistance, corrosion resistance, high temperature chemical stability, excellent thermal conductivity, low thermal expansion coefficient, good strength and specific stiffness, etc., and are used as functional devices and structural materials; many stu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B31/36C01B32/97
Inventor 何方陈松林吴菊英
Owner HENAN UNIVERSITY OF TECHNOLOGY
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