FABRICATION CONDITION OF TRANSPARENT OH F REE SINTERED SILICA GLASS

Green compacts of high-purity silica powders with different particle s izes were formed by slip casting method and pressureless-sintered. Con ditions to fabricate transparent silica glasses are presented using di agrams described by sintering-temperature and-time. The variation of l inear shrinkage with time reveals that the sintering mechanism at its early stage follows the viscous flow of silica glass particles. The ef fect of firing schedule on residual OH concentration was studied for t ransparent sintered silica glasses. A green compact prepared by silica powders with a mean particle size of 1.6 mu m was fired at 1573 K for 3h for dehydration and heated up to 1873 K for densification; this ty pical fabrication condition results in a transparent sintered silica g lass with <1 ppm OH concentration.