SECTION-9 - MANUFACTURING METHODS OPTICAL FIBERS THERMAL AND PLASMA OXIDES CRYSTALLIZATION - COMPARISON OF HIGH-PURITY H-2 O-2 AND LPG O-2 FLAME-FUSED SILICA GLASSES FROM SOL-GEL SILICA POWDER

High-quality flame-fused silica glasses were obtained from high-purity starting sol-gel silica powders, under H-2/O-2 and liquid propane gas (LPG)/O-2 flames. Neither metallic nor carbon contamination was obser ved during the fusion process, even by using domestic LPG. The flame-f used sol-gels showed lower impurity levels than silica glasses from na tural quartz and of the same order as the commercial synthetic silica glasses (chemical vapor deposition process). By fusion with an LPG/O-2 flame, the aggregation of OH radicals during the fusion process was v erified to be about 100 ppm lower with viscosity two times higher than that of silica glasses fused by H-2/O-2. The viscosity of this flame- fused sol-gel silica is lower than the flame-fused silica from rock cr ystal, but is one order of magnitude higher than that of the synthetic silica glass.