| 摘要 |
PROBLEM TO BE SOLVED: To provide a synthetic amorphous silica powder which causes very little occurrence of bubbles and expansion even when used in environments at high temperatures and reduced pressures and is suitable as a raw material for synthetic silica glass products and its production method.SOLUTION: A synthetic amorphous silica powder is obtained by sintering a granulated silica powder, spheroidizing the sintered silica powder and cleaning and drying the spheroidized powder. The silica powder has a mode value Dof the grain size distribution by volume of 50-200 μm with a frequency of 2-5%, an average grain size Dby number of 0.4×D±10 μm, a mode value Dof the grain size distribution by number of 5-10 μm with a frequency of 3-10%, a hardened bulk density of ≥1.38 g/cmand ≤1.50 g/cm, a circularity of ≥0.85 and ≤1.0 and a concentration of carbon lower than 2 ppm and/or a concentration of chlorine lower than 2 ppm. |
