Silicon carbide aerogel material and preparation method thereof

A technology of airgel and silicon carbide, applied in chemical instruments and methods, carbon compounds, inorganic chemistry, etc., can solve the problems of poor crystallinity, complex preparation process, and single phase of silicon carbide airgel, and achieve good chemical stability Sexuality, simplification of the preparation process, and low cost

Active Publication Date: 2022-04-12
NANJING UNIV OF INFORMATION SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The object of the present invention is to solve the complex preparation process of the organic / silica airgel precursor, the high cost, the collapse of the structure in the high temperature carbothermal reduction process and the prepared carbonization Silica airgel has poor crystallinity and contains impurity phases. It is proposed to use sol-gel combined with vacuum drying to prepare organic bridged hemisiloxane airgel precursor, and then through a high-temperature carbothermal reduction process to obtain a good crystallinity , monolithic and structurally complete bulk SiC airgel

Method used

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  • Silicon carbide aerogel material and preparation method thereof
  • Silicon carbide aerogel material and preparation method thereof
  • Silicon carbide aerogel material and preparation method thereof

Examples

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Embodiment 1

[0027] Terephthalaldehyde (4mol), 3-aminopropyltriethoxysilane (1mol), tetraethoxysilane (0.5mol), methyltrimethoxysilane (0.5mol), ethanol (50ml), de Ionized water (10ml) and acetic acid (1ml) were mixed evenly, and then the mixed solution was placed in a constant temperature oven at 50°C for 48h to fully gel. The wet gel obtained above was placed in a constant temperature environment of 60° C., and replaced with ethanol 6 times, 12 hours each time. Then the wet gel was placed in a vacuum drying oven, dried at 40° C. for 12 hours, and then dried at 80° C. for 12 hours to obtain polysiloxane airgel. The above polysiloxane airgel was heated up to 1400° C. at a heating rate of 1° C. / min under an argon atmosphere, kept for 5 hours, and then naturally cooled to obtain a silicon carbide ceramic airgel. The airgel surface is a gray-green thin layer, and the interior is a black block, which is composed of silicon carbide crystals and silicon oxygen carbon amorphous ( figure 1 ), th...

Embodiment 2

[0029] Terephthalaldehyde (4mol), 3-aminopropyltriethoxysilane (4mol), tetramethoxysilane (2mol), tetramethyldisiloxane (2mol), ethanol (10ml), deionized Water (5ml) and acetic acid (0.5ml) were mixed evenly, and then the mixed solution was placed in a constant temperature oven at 70°C for 36h to fully gel. The wet gel obtained above was placed in a constant temperature environment of 70° C., and replaced with n-hexane 4 times, 6 hours each time. Then the wet gel was placed in a vacuum drying oven and dried at 100° C. for 6 hours to obtain polysiloxane airgel. The above polysiloxane airgel was heated up to 1500°C at a heating rate of 3°C / min in an argon atmosphere, kept for 5 hours and then cooled naturally to obtain a silicon carbide ceramic airgel. The airgel is a gray-green block, and its composition is composed of silicon carbide crystals ( figure 2 ), the interior presents a three-dimensional porous network structure ( image 3 ), the density is 0.090g / cm 3 , thermal...

Embodiment 3

[0031] Terephthalaldehyde (4mol), 3-aminopropyldiethoxymethylsilane (2mol), phenyltrimethoxysilane (2mol), ethanol (10ml), deionized water (5ml) and acetic acid (1ml ) were mixed evenly, and then the mixed solution was placed in a constant temperature oven at 80° C. for 12 hours to make it fully gel. The wet gel obtained above was placed in a constant temperature environment of 40° C., and replaced with isopropanol 6 times, each time for 12 hours. Then the wet gel was placed in a vacuum drying oven, dried at 60° C. for 6 hours, and then dried at 90° C. for 8 hours to obtain polysiloxane airgel. The above polysiloxane airgel was heated up to 1600°C at a heating rate of 5°C / min under an argon atmosphere, kept for 2 hours and then cooled naturally to obtain a silicon carbide ceramic airgel. The airgel is a gray-green block, and its composition is composed of silicon carbide crystals ( Figure 4 ), the density is 0.085g / cm 3 , thermal conductivity 0.04W / (m·K), temperature resis...

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Abstract

The invention belongs to the field of ceramic aerogel, and discloses a silicon carbide aerogel material and a preparation method thereof.The preparation method comprises the following steps that 1, terephthalaldehyde, amino silane, organosiloxane, acetic acid, ethyl alcohol and deionized water are mixed to be uniform, and polysiloxane wet gel is obtained through organosilane hydrolysis copolycondensation reaction; (2) performing aging and vacuum drying on the polysiloxane wet gel obtained in the step (1) to obtain polysiloxane aerogel; and (3) heating the polysiloxane aerogel obtained in the step (2) to 1400-1600 DEG C in an argon atmosphere at a heating rate of 1-5 DEG C / min, and carrying out high-temperature heat treatment for 2-5 hours to obtain the blocky silicon carbide aerogel. According to the invention, sol-gel is combined with vacuum drying to prepare an organic bridged silsesquioxane aerogel precursor, and then the blocky silicon carbide aerogel with good crystallinity, single phase and complete structure is obtained through a one-step high-temperature carbon thermal reduction process.

Description

technical field [0001] The invention relates to the field of ceramic airgel, in particular to a silicon carbide airgel material and a preparation method thereof. Background technique [0002] Silicon carbide airgel is suitable for a variety of applications in high temperature and high corrosion environments, such as high temperature heat insulation, electromagnetic wave absorption, etc. , Filtration and catalyst carrier, etc. [0003] The preparation methods of silicon carbide airgel mainly include the following three types. (1) Carbon thermal reduction method of organic / silica composite airgel. Firstly, organic / silica composite airgel is prepared by sol-gel method combined with supercritical drying as a precursor, and then carbonized to obtain carbon / silica composite airgel, and carbon / silica composite airgel is then subjected to high-temperature carbothermal reduction A silicon carbide airgel (CN102897764B) was obtained. (2) Pre-ceramic polymer cracking method. Firstl...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/571C04B35/622C04B35/624C01B32/977
Inventor 邵高峰丁成蹊胡东孝赖一凡黄啸谷
Owner NANJING UNIV OF INFORMATION SCI & TECH
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