PRODUCTION OF QUARTZ-BASED GLASS PREFORM

摘要

PURPOSE:To prevent fine air bubbles from occurring in the central part of a porous glass body by arranging two kinds of silica-based glass powdery materials having a different particle diameter on the outer periphery of a formed body and forming the glass powdery materials. CONSTITUTION:A silica glass rod 1 is arranged in the center of a rubber mold 4 for hydraulic pressure forming and two kinds of cylindrical charging containers 2 and 3 having different diameters are concentrically inserted into the interior of the rubber mold 4. Silica-based glass powdery materials (a) and (b) having <=1mum primary particle diameter are filled in the container 2 and silica-based glass powder (c) having 1-20mum primary particle diameter is filled in the container 3. The containers 2 and 3 are then taken out. The rubber mold 4 is subsequently set in an isostatic pressing device and pressurized in the longitudinal direction by a dry packing method. Thereby, the powder forming is carried out.