A kind of high temperature resistant aluminum oxide nanocrystalline airgel material and preparation method thereof

Abstract

The invention relates to a high-temperature resistant aluminum oxide nanocrystalline airgel material and a preparation method thereof. The method is as follows: uniformly mix aluminum oxide nanocrystals and chitosan solution to obtain a mixed solution, add glacial acetic acid to dissolve chitosan, and then heat at 60-100°C for 4-8 hours to obtain alumina nanocrystal chitosan Dispersion liquid; the dispersion liquid is subjected to a vacuum pumping process to obtain an alumina nanocrystal / chitosan reaction liquid; the reaction liquid is frozen and freeze-dried, and then subjected to high-temperature cracking to obtain an alumina / carbon composite airgel ; The alumina / carbon composite airgel is heat-treated in an air atmosphere to prepare a high-temperature-resistant alumina nanocrystalline airgel material. The invention obtains alumina / carbon composite airgel through pyrolysis at high temperature. Since the carbon coating layer can fix the nanoparticles and play a certain role in isolation, the sintering of the material is prevented, and the material transitions to the airgel without sintering. The stable crystal form realizes the preparation of high temperature resistant alumina airgel.

Description

A kind of high temperature resistant alumina nanocrystalline aerogel material and preparation method thereof technical field The present invention relates to aerogel preparation technical field, relate in particular to a kind of high temperature resistant alumina nanocrystalline aerogel material and its preparation method. Background technique Aerogel material is a kind of gel material whose dispersion medium is gas, which is composed of colloidal particles or polymer molecules. A nanoporous solid material with a network structure composed of aggregates, the size of the pores in the material is in the order of nanometers. class. Its porosity is as high as 80~99.8%, the typical size of pores is 1~100nm, and the specific surface area is 200~1000m 2 / g, while Densities as low as 3kg / m 3 , the room temperature thermal conductivity can be as low as 0.012W / m·k. It is precisely because of these characteristics that aerogel materials are It has broad application ...

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Problems solved by technology

Carbon aerogels and ceramic aerogels have good high temperature resistance, but there are certain limitations in their application, that is, thermal insulation applications above 1400 °C can only be achieved in an oxygen-free environment, while carbon aerogels and ceramic aerogels There is no effective way to overcome the antioxidant

Oxide aerogels such as silica, alumina, and zirconia will undergo severe crystal transformation and sintering at high temperatures, leading to structural collapse, resulting in the growth of nanoparticles and the reduction of pores, so that the specific surface area of ​​the aerogel will decrease sharply. decline, greatly weakening its thermal insulation performance and failure of thermal insulation

Aiming at the limitations of oxide aerogels, related studies have carried out modification processes such as rare earth metal oxides or multi-component doping, but their effects are limited

[0004] Chinese patent application CN201810068117.1 discloses a method for preparing high-temperature-resistant airgel materials, although the airgel prepared by this method has good high-temperature resistance characteristics, and the heat-resistant temperature is above 1000°C, and can even withstand above 1300°C High temperature, but the airgel material will still produce a series of phase transitions at high temperatures above 1200 °C, making its specific surface area after high temperature heat treatment at 1400 °C small, no more than 10m 2 / g, so the high temperature insulation performance of the airgel material is not very good

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