| 摘要 |
Disclosed is a synthetic amorphous silica powder which is obtained by subjecting a silica powder to spheroidizing treatment and then firing the resulting silica powder without cleaning. The synthetic amorphous silica powder is characterized by having a value, which is obtained by dividing the BET specific surface area by the theoretical specific surface area as calculated from the average particle diameter D50, of not more than 1.93, a true density of not less than 2.10 g/cm3, an intramolecular porosity of not more than 0.05, a circularity of not less than 0.50, and a spheroidization ratio of not less than 0.20. The synthetic amorphous silica powder is also characterized in that a fine silica powder is adhering to the surface of the synthetic amorphous silica powder. Since the amount of gas components adsorbed on the surface of the synthetic amorphous silica powder or contained in the powder is little, a synthetic silica glass product that is produced using the powder can be greatly reduced in generation or expansion of gas bubbles even when used in a high temperature and reduced pressure environment. |
