Preparation method of mullite-fibrofelt-reinforced SiO2-Al2O3 aerogel composite heat-insulating material

Abstract

The invention relates to a preparation method of a mullite-fibrofelt-reinforced SiO2-Al2O3 aerogel composite heat-insulating material, which comprises the following steps: by using surface-pretreated mullite fibrofelt as a reinforcer, tetraethyl orthosilicate as a silicon source, cheap inorganic aluminum salt as an aluminum source and epoxide as a network formation agent, uniformly mixing, and carrying out sol-gel, aging and supercritical drying to obtain the mullite-fibrofelt-reinforced SiO2-Al2O3 aerogel composite heat-insulating material. In the preparation process, no catalyst is needed, and a one-step method is adopted to greatly optimize the preparation technique. Thus, the heat-insulating material has the advantages of low cost, smooth surface and controllable thickness, and can resist the temperature of 1200 DEG C in an air atmosphere. The room temperature thermal conductivity is 0.023-0.027 W.m<-1>K<-1>, and the apparent density is 0.18-0.22 g/cm<3>. The method has the advantages of simple materials, low cost and simple technique, is simple to operate in the technical process, and can easily implement large-scale production.

Description

technical field [0001] The invention belongs to the field of preparation technology of nanoporous materials, and relates to a mullite fiber mat reinforced SiO with high temperature resistance and low thermal conductivity 2 -Al 2 o 3 The invention discloses a preparation method of an airgel composite thermal insulation material. Background technique [0002] With the development of aerospace technology, the flight speed of various aircraft is developing towards a high Mach number, and the severe friction with the atmosphere during the flight will cause a strong aerodynamic heating problem. In order to make it fly faster and for a longer flight time, while ensuring the safety of internal personnel and related equipment, high-efficiency heat insulation materials with high temperature resistance and low thermal conductivity must be used. [0003] Airgel is a nanoporous material formed by the aggregation of nanoparticles. The high porosity of the airgel material can reduce the...

AI Technical Summary

Problems solved by technology

SiO 2 The room temperature thermal conductivity of airgel is as low as 0.013W m -1 K -1 , but the temperature resistance of this material is poor, and the pore structure will collapse seriously above 800 °C, and the heat insulation performance will drop sharply

al 2 o 3 The temperature resistance of airgel is high, up to 1000 °C, but the material is prone to crystal transformation in high temperature environment, and the high temperature thermal conductivity is high, so through the Al 2 o 3 Aerogels are doped with silicon to prepare SiO 2 -Al 2 o 3 Composite airgel has both high temperature resistance and low high temperature thermal conductivity

Feng Jian and others from the University of National Defense Science and Technology used aluminum sec-butoxide as the aluminum source and tetraethyl orthosilicate as the silicon source to successfully prepare a compound with a specific surface area of ​​116m at 1200°C. 2 / g SiO 2 -Al 2 o 3 composite aerogels, and systematically studied the effect of silicon content on SiO 2 -Al 2 o 3 However, in this method, the aluminum source and the silicon source need to be prepared separately to fully hydrolyze, and the organoaluminum alcohol itself is expensive, and the hydrolysis speed of the organoaluminum alcohol is relatively fast, and the hydrolysis process is easy A colloidal precipitate is produced, and methanol and glacial acetic acid need to be introduced in the subsequent steps, and the preparation process is relatively complicated

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