Atmospheric Drying Process and Properties of SiO₂ Aerogels

Abstract

In this paper, tetraethyl orthosilicate and anhydrous ethanol were used as raw materials, and hexane was used for solvent replacement of the gel. Surface modification of three methyl silane (TMCS) was carried out, and SiO2aerogels were prepared by sol-gel process and atmospheric drying process. The effect of TMCS and the calcination temperature on the properties of the SiO2gel were studied. The physicochemical properties of aerogels were characterized by field emission electron microscopy (FESEM), energy dispersive spectrometry (EDS), X ray diffraction (XRD), infrared analysis (FT-IR) and specific surface area (BET). The results show that the material is composed of round nanoparticles with a diameter of less than 20 nm. EDX analysis shows that the material is composed of Si and O elements. The XRD spectrum shows no obvious characteristic diffraction peak when SiO2aerogels calcinated at 500 °C and 900 °C, which indicates that the phase group of the material is disordered amorphous SiO2; when calcinated at 1100 °C, it occure SiO2crystal. After 10 hours of modification with 20% TMCS/hexane solution, the SiO2aerogels had a larger specific area. The BET of the modified aerogel is about 930 m2/g.