High-temperature-resistant aluminum oxide nanocrystal aerogel material and preparation method thereof

Abstract

The invention relates to a high-temperature-resistant aluminum oxide nanocrystal aerogel material and a preparation method thereof. The method comprises the steps: uniformly mixing aluminum oxide nanocrystals and a chitosan solution to obtain a mixed solution, adding glacial acetic acid to dissolve chitosan, and heating at the temperature of 60-100 DEG C for 4-8 h to obtain a chitosan dispersion solution of the aluminum oxide nanocrystals; carrying out a vacuum pumping process on the dispersion liquid to obtain an aluminum oxide nanocrystal / chitosan reaction liquid; carrying out freezing and freeze drying on the reaction liquid, and carrying out high-temperature cracking to obtain aluminum oxide / carbon composite aerogel; and carrying out heat treatment on the aluminum oxide / carbon composite aerogel in an air atmosphere to prepare the high-temperature-resistant aluminum oxide nanocrystal aerogel material. The aluminum oxide / carbon composite aerogel is obtained through high-temperature cracking, and the carbon coating layer can fix the nanoparticles and has a certain isolation effect, so that the sintering effect of the material is prevented, the material is transited to a stable crystal form under the condition that the material is not sintered, and the preparation of the high-temperature-resistant aluminum oxide aerogel is realized.

Description

technical field [0001] The invention relates to the technical field of aerogel preparation, in particular to a high temperature resistant alumina nanocrystalline aerogel material and a preparation method thereof. Background technique [0002] Aerogel material is a kind of gel material whose dispersion medium is gas. It is a kind of nanoporous solid material with network structure composed of colloidal particles or polymer molecules that accumulate with each other. The size of pores in this material is in the order of nanometers. . 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 the density can be 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 have broad application potential in thermal, acoustics, optics, microelectronics, and particle detection. At present, the most widely us...

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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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