1988 Volume 96 Issue 1110 Pages 171-175
A new method for preparing fine silica particles was developed by the reaction of silicon powder and water vapor at 990°-1200°C in the presence of hydrogen sulfide. If hydrogen sulfide was absent in the reaction system, oxidation of silicon occurred only on the silicon powder surfaces and no silica particles were produced. In contrast, a large amount of fine silica particles was formed at 990°-1200°C when hydrogen sulfide was mixed. Conversion of silicon to silica was maximun (63%) at 1060°C and the optimum reaction time was 2h in view of the conversion and the uniform particle size. The particle size. The particle size distribution was relatively narrow with the average particle diameter of 0.09-0.1μm for the products collected in a flask which was placed at the downstream of the reactor. Thermodynamic consideration suggested that silica particles form via volatile SiS or SiS2 intermediates and that the morphology of fine particles is associated with homogeneous nucleation in the vapor phase.
