| 摘要 |
PURPOSE:To obtain readily silica glass not forming goams even at high temperature, by subjecting dried silica gel from which absorbed water and carbon are removed to hydroxyl group removal and dechlorination treatment and pore removal treatment. CONSTITUTION:Dried silica gel is subjected to absorbed water removal treatment at about 250 deg.C, and to carbon removal treatment in an oxidizing atmosphere at about 700 deg.C. The silica gel is then heated upto from about 700 deg.C to about 1,000-about 1,050 deg.C in an atmosphere containing not less than 1wt% Cl2 so that it is subjected to hydroxyl group removal treatment. The silica gel is heated upto about 1.000- 1,100 deg.C in an atmosphere containing not less than 1wt% oxygen and maintained at a given temperature for not less than 2hr so that dechlorination treatment is carried out. This silica material is heated upto about 1.050-about 1,300 deg.C in He or under vacuum and maintained at a given temperature for not more than 1hr so that pore removal treatment is carried out. The silica gel thus obtained will not form foams at all by heating it at high temperature about not lower than 1,300 deg.C, can be formed by a given processing readily, and is fit as a parent material for optical fiber. |
