Preparation method of ultralight high-temperature-resistant blocky mullite aerogel

Abstract

The invention provides a preparation method of ultralight high-temperature-resistant blocky mullite aerogel, which comprises the following steps: by taking an aluminum-containing two-dimensional porous crystalline metal covalent organic framework material as an aluminum source, silicate ester as a silicon source and a water-soluble linear polymer as an additive, carrying out organic alkali treatment to form a mixed dispersion liquid, and carrying out freeze drying and roasting at 1200 DEG C in an air atmosphere to obtain the ultralight high-temperature-resistant blocky mullite aerogel. The ultralight high-temperature-resistant blocky mullite aerogel is prepared. The blocky mullite aerogel obtained by the method disclosed by the invention is complete in structure after being roasted at 1200 DEG C in an air atmosphere, and the density is as low as 26 mg / cm < 3 >. The invention has the characteristics of low raw material cost, simple preparation process, excellent product performance and easy realization of industrial large-scale production.

Description

technical field [0001] The invention relates to the synthesis of novel materials, in particular to the preparation of an ultra-light massive mullite airgel which can withstand 1200 degrees in air. Background technique [0002] At present, inorganic oxide aerogels are the most researched airgel thermal insulation materials. Among them, silica aerogels have been commercially produced and applied, but the long-term use temperature of silica aerogels cannot exceed 650 degrees, which is greatly The application in high temperature field is limited. The use temperature of alumina airgel can exceed 1000 degrees, but when the temperature reaches 1200 degrees, the crystal phase will change into dense α-alumina, the thermal conductivity will increase significantly, and alumina airgel will easily lose powder and slag , is difficult to shape, which severely limits its application range. [0003] In order to solve the problem of high-temperature phase transition of alumina, the conventi...

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Problems solved by technology

[0004] CN201310276044.2, CN201410510404.5 and Shen Jun etc. used the in-situ water generation method to control the synthesis of alumina sol-gel, and used supercritical modification and gas phase high-temperature modification methods to synthesize silica-modified alumina gas condensation Glue, which can remain in the θ-alumina phase at 1300 degrees, does not change into α-alumina, and has a low thermal conductivity at high temperatures, but this method is complicated and difficult to achieve in industrial production

[0005] T.HEINRICH et al. used aluminum sec-butoxide as the aluminum source, tetraethyl orthosilicate as the silicon source, and synthesized mullite airgel through the sol-gel method controlled by acid and alkali, which can be used as heat insulation at 1200 degrees However, due to the difference in the acid-base conditions in the gelation process of alumina sol and silica sol, it is difficult to achieve uniform dispersion of the two at the molecular level, and it is impossible to synthesize mullite airgel with a complete block structure, and the super Critical extraction technology is difficult to achieve industrial production

[0006] CN201910954101.5 uses aluminum isopropoxide as the aluminum source, tetraethyl orthosilicate as the silicon source, and mixes with water-soluble polymers to obtain a spinning solution with a certain viscosity, which is gelled after jet spinning and then roasted at high temperature Methods The mullite fiber airgel that can withstand 1200 degrees was synthesized. This material has low density and thermal conductivity, good stress deformation, and the drying process does not use supercritical extraction technology, but the spinning method has low production efficiency. Still difficult to achieve in industry

[0007] CN201910393603.5 directly uses mullite nanofibers as raw materials, uses silica sol as a crosslinking agent, and adopts acrylamide gel casting for gelation, and prepares light-weight and high-temperature-resistant mullite aerosol by freeze-drying method Glue, the process of this method is relatively simple, but it is difficult to obtain industrial raw materials for mullite nanofibers, and it is impossible to realize industrial mass production

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