Study On Preparation Of Silica Aerogels Derived From Silica Sol

Silica aerogels is a lightweight nano-porous material, the density, porosity, particle and holes size were 0.003～0.5g/cm3,～99%, and in the range of 1～100nm. Its fine structure have excellent insulation properties, as a lightweight efficient insulation material has broad application prospects. Currently TEOS usually used as silicon source and the supercritical drying of aerogel were complex, time-consuming, inefficient and costly. Study of atmospheric drying technology is still lack, and structure and properties can not compile with supercritical drying method, while not modified silica aerogel is hydrophilic, which limits the silica aerogel material industrial application.In this paper, study the preparation of aerogel that use cheap raw materials silica sol as silica source. Reach on how system constituent , system PH value, the addition of formamide, wet gel aging and surface hydrophobic treatment, as well as drying process that influence aerogel aerogel performance., establish a theoretical model and computing, contrastive analysis results with the real results to determine which is the key indicators of thermal conductivity.Test results: ethanol/silica sol has a significant impact on the density and gel time, silica sol, ethanol and water for the best ratio of 8:16: 1; the best value system PH is 5; add 1/16Vsilica sol formamide will obtain uniform gel structure, use TEOS/ethanol solution on the wet gel to aging and improve wet strength gel network structure to enable it to bear in the tension during drying process to avoid contraction or collapse phenomenon, use Chlorotrimethylsilane, n-hexane, isopropanol on the wet surface modification hydrophobic treatment, a silicon aerogel drying process in 45℃; SEM show that aerogels particle diameter and uniform pore size were about 30nm and 50nm,the dentisy is about 0.3g/cm3; a small spherical rod-shaped structure was establish for thermal conductivity, the result show: density is a key indicator that influence the thermal conductivity of the bulk aerogel.