| 摘要 |
PURPOSE:To prevent the cracking of a quartz glass in sintering step, to enable the production of a sintered glass having high density, and to improve the mass-productivity of quartz glass, by storing the dry gel in a closed vessel before charging into a sintering furnace in the production of a quartz glass by sol-gel process. CONSTITUTION:A quartz glass is produced by the sol-gel process using an alkyl silicate and ultrafine silica powder as raw materials. In the above process, the dry gel produced by the gelation and drying of a silica sol is stored in a closed vessel before charging the gel into a sintering furnace. The drying is preferably carried out in a hot dry atmosphere at >=50 deg.C. The dry gel produced by the sol-gel process has strong water-absorption because of its high porosity and the adsorbed water is desorbed in the sintering stage. Since the adsorption of water to the dry gel can be prevented by the above process, the generation of crazings and cracks of the quartz glass in the sintering stage can be prevented. |
