The production of ultrafine silica powders from silicon tetrachloride: Control of the primary particle size
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Ultra fine silica powders were prepared by hydrolysis of SiCl4 using aqueous ammonia solution followed by supercritical drying. Using different methods of combining the SiCl4 and ammonia solution, to vary the initial and final pH of the solution, large silica powders surface areas (271–905 m2/g), fine average particle diameters (3.5–17) nm and low tapping densities (0.02–0.05 g/cm2) could be prepared. Powders with characteristics similar to pyrogenic silica, and with similar thermal stability at temperatures up to 1000°C, could be produced.
Key wordssilicon tetrachloride particle size silica aerogel powders
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