| 摘要 |
PURPOSE:To produce high-quality glass in high productivity, by producing SiO2 powder containing a phase-transition promoter by a specific method, heat- treating the powder to obtain grown cristobalite crystal phase and melting the phase by heating in vacuum. CONSTITUTION:SiO2 powder having particle diameter of <=0.1mu is mixed with a solution containing a phase-transfer promoter (e.g. metallic component such as Na2O, MgO, etc.), dehydrated, dried and pulverized to obtain granular SiO2 powder having particle diameter of 50-500mu and containing the phase-transfer promoter without varying the specific surface area of the powder. The granular powder is filled in a vessel and heated to obtain a sintered form containing cristobalite crystal phase. The formed product is vitrified by melting in vacuum. Since the present process easily affords a porous sintered material having sufficiently high substrate strength for the following processes and advantageous for deaeration treatment, a high-quality glass material can be produced in high productivity. |
