| 摘要 |
Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 150±15 m<SUP>2</SUP>/g, wherein the aggregates display an average surface area of 12000 to 20000 nm<SUP>2</SUP>, an average equivalent circle diameter (ECD) of 90 to 120 nm and an average circumference of 1150 to 1700 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a second silicon component comprising H<SUB>3</SUB>SiCl, H<SUB>2</SUB>SiCl<SUB>2</SUB>, HSiCl<SUB>3</SUB>, CH<SUB>3</SUB>SiCl<SUB>3</SUB>, (CH<SUB>3</SUB>)<SUB>2</SUB>SiCl<SUB>2</SUB>, (CH<SUB>3</SUB>)<SUB>3</SUB>SiCl and/or (n-C<SUB>3</SUB>H<SUB>7</SUB>)SiCl<SUB>3 </SUB>are mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1670 to 1730° C. is obtained. Silicone sealing compound containing the pyrogenically produced silicon dioxide powder.
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