Composite fiber-reinforced hydrophobic SiO2 aerogel and preparation method thereof

Abstract

The invention belongs to the field of advanced composite materials and particularly relates to a composite fiber-reinforced hydrophobic SiO2 aerogel and a preparation method thereof. In the method, a proper silicon source is employed as a precursor and a sol-gel method is employed. The method includes the following steps: 1) fully mixing pre-treated composite fibers with sol, performing aging treatment and performing surface modification; 2) connecting a hydrophobic group on the surface of the gel to achieve a hydrophobic effect; 3) replacing the solvent, such as ethanol, water and the like which are high in surface tension, with a low-surface-tension solvent through solvent replacement to reduce capillary tension in the liquid during drying, thereby reducing the phenomenon of gel collapse caused by evaporation of the solvent during a normal-pressure drying process; and 4) performing the normal-pressure drying process to prepare the hydrophobic SiO2 aerogel composite material. The method is simple and quick, is reduced in production cost, can improve both the strength and toughness of the composite aerogel and broadens the application of SiO2 aerogel on surfaces of irregular-shaped objects.

Description

technical field [0001] The invention belongs to the field of advanced composite materials, in particular to a composite fiber reinforced hydrophobic SiO 2 Aerogels and methods of making them. Background technique [0002] SiO 2 Airgel is a nanoporous amorphous material with a three-dimensional network structure. This special structure makes it have a specific surface area up to 1000m 2 / g, the density is as low as 3kg / m 3 , the porosity is as high as 99.8% (the pore size and the colloidal particle size are within 1-100nm and 2-60nm respectively), and the ultra-low thermal conductivity is 0.015W / (m·K). Many excellent properties make it widely used in aerospace, chemical industry, electrochemistry, metallurgy and many other fields. [0003] In recent years, due to pure SiO 2 The low density and high porosity of airgel lead to its poor mechanical properties, such as low strength and poor toughness, so it cannot be used alone in thermal insulation projects. Without affect...

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Problems solved by technology

ZHANG et al prepared SiO by adding glass fibers 2 airgel material, but the glass fiber is relatively brittle, which makes the prepared glass fiber reinforced airgel material rigid and less flexible

Ni Wen et al. used calcium silicate to enhance the preparation of SiO 2 The airgel composite material has a flexural strength of 0.18MPa, but the prepared airgel cannot have good strength and toughness at the same time

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