| 摘要 |
The synthetic amorphous silica powder of the present invention is obtained by applying a spheroidizing treatment to a granulated silica powder, and by subsequently cleaning and drying it so that the synthetic amorphous silica powder has an average particle diameter D 50 of 10 to 2,000µm; wherein the synthetic amorphous silica powder has: a quotient of greater than 1.35 and not more than 1.75 obtained by dividing a BET specific surface area of the powder by a theoretical specific surface area calculated from the average particle diameter D 50 ; a real density of 2.10 to 2.20g/cm 3 ; an intra-particulate porosity of 0 to 0.05; a circularity of 0.50 to 0.75; and an unmolten ratio of greater than 0.25 and not more than 0.60. Since this synthetic amorphous silica powder has less gas components that are adsorbed onto surfaces of particles of a raw powder and less gas components inside the powder particles, generation or degree of expansion of gas bubbles are markedly reduced in a synthetic silica glass product which beet manufactured by using this synthetic amorphous silica powder even upon usage of the product in a high temperature and reduced pressure environment. |
