Preparation method of high-temperature-resistant silicon carbide aerogel with directional hole structure
A technology of high temperature resistance and silicon carbide is applied in the field of preparation of high temperature resistant silicon carbide aerogel, which can solve the problems of high thermal conductivity of aerogel, high preparation cost and complicated process.
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[0048] combinefigure 1 As shown, in one embodiment, the preparation method of the high temperature resistant silicon carbide aerogel having an oriented pore structure comprises the following steps:
[0049] S10, mixing and stirring the nanocellulose dispersion with the silicon source to obtain a wet gel;
[0050] Specifically, in step S10, the mass fraction of the nanocellulose dispersion is 0.1% to 7%, the length of the nanofibers in the nanocellulose dispersion is 50 to 1000 nm, and the solvent of the nanocellulose dispersion Including one or more of water, 2-methyl-2-propanol, ether and glycerin, in the nanocellulose dispersion, the nanofibers include cotton nanofibers, wood pulp nanofibers, sisal nanofibers, One or more of bacterial nanofibers and carboxylated nanofibers, the silicon source includes SiO powder, SiO2 powder, water glass, tetraethylorthosilicate, methyltrimethoxysilane, dimethyldimethoxy One or more of base silane, tetramethylsilane and hexamethyldisiloxane...
Embodiment 1
[0076] (1) Take 20g of cotton nanocellulose dispersion with a mass fraction of 1% and a fiber length of 100nm, mix it with 2.1g of SiO powder, stir it and leave it to stand to obtain a wet gel;
[0077] (2) introducing the wet gel into a mold, and placing it on a directional freezing device, and performing a directional freezing treatment with liquid nitrogen for 0.5 h to obtain a block gel;
[0078] (3) After freezing, take out the block gel and transfer it to a vacuum dryer, the pressure of the vacuum drying treatment is 15Pa, and the drying treatment time is 10h, to obtain nanocellulose / SiO airgel;
[0079](4) The obtained nanocellulose / SiO airgel was sintered at a high temperature in argon for 2 hours, the heating rate was 4°C / min, and the holding temperature was 1200°C to finally obtain a silicon carbide airgel material with an oriented pore structure.
[0080] It should be noted that the airgel material obtained by the preparation method of the high-temperature-resistant...
Embodiment 2
[0082] (1) Take 20 g of cotton nanocellulose dispersion with a mass fraction of 6% and a fiber length of 1000 nm, mix it with 5.5 g of TEOS solution, stir evenly and leave it to stand to obtain a wet gel;
[0083] (2) introducing the wet gel into a mold, and placing it on a directional freezing device, and performing a directional freezing treatment with liquid nitrogen for 4 hours to obtain a block gel;
[0084] (3) After freezing, take out the block gel and transfer it to a vacuum dryer, the pressure of the vacuum drying treatment is 20Pa, and the drying treatment time is 10h, to obtain nanocellulose / TEOS airgel;
[0085] (4) The obtained nanocellulose / TEOS airgel was sintered at a high temperature in argon for 3 hours, the heating rate was 4°C / min, and the holding temperature was 1400°C, and finally a silicon carbide airgel material with an oriented pore structure was obtained.
[0086] It should be noted that the airgel material obtained by the preparation method of the hi...
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