PRODUCTION OF QUARTZ-BASED GLASS PREFORM

摘要

PURPOSE:To remove impurities, eliminate bubbles and improve the quality by preparing a porous preform having one or more holes in the longitudinal direction according to a powder forming method using quartz-based powder and then subjecting the resultant preform to the purifying treatment. CONSTITUTION:A stainless steel rod 10 is arranged in silica powder having about 4mum average particle diameter and the silica powder, together with the stainless steel rod 10, is then charged into a rubber mold 11 for hydraulic pressure forming and filled therein while being vibrated with a vibrator. The mold 11 is subsequently pressurized in all the directions under about 1t/cm<2> pressure for about 1min and returned to the atmospheric pressure taking about 10min. The prepared porous preform 12 having a through-hole 13 is then taken out of the rubber mold 11 to pull out the stainless steel rod 10. The resultant preform 12 is then subjected to the purifying treatment by heating at 1100 deg.C in a mixed gas atmosphere of He gas with chlorine gas and transparently vitrified to produce the quartz-based glass preform.