This project investigated density, thermal conductivity, porosity and light transmission characteristics of silica-aerogels fabricated using the "Fast Supercritical Extraction Technique for Simplified Aerogel Fabrication" developed at Union College. Aerogels are the lightest known solids and can be made up of 99% air. They are very attractive for use as insulation, as biological/chemical sensors, fuel storage and particle collectors. The aerogels were prepared by hydrolysis and polycondensation of tetramethylorthosilicate, using a hydraulic hot-press for supercritical drying in a one-step process. Methanol was used as the solvent with catalytic ammonium hydroxide. The physical properties were measured using a microbalance, a thermal-constants analyzer, a nitrogen gas adsorption system and a spetrophotometer. Process tests have resulted in a two-fold decrease in the amount of time to form the aerogel and a decrease in aerogel density from 0.3g/cm3 to 0.06g/cm3. The surface area measurements using a 6 point BET analysis with nitrogen were between 320 m2/g and 440 m2/g, while average pore sizes obtained from BJH calculations were between 10nm - 16nm. The measured thermal conductivity using the transient plane source method was 0.035W/m/K.

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updated March 18, 2003