| 摘要 |
PURPOSE:To sinter a porous glass material easily at a relatively low temperature without causing the deterioration, deformation, etc., by converting the surface of the porous glass material into a molten nonporous glass layer, and sintering the molded material under heating at a static pressure with a fluid. CONSTITUTION:A porous glass material 20 obtained by forming fine glass particles formed by the vapor axial depsoition (VAD) method, outside vapor deposition method or modified vapor deposition method or phase separation is heated in a short time to melt and convert the surface layer thereof into a molten nonporous glass film layer 21 covering thereon. The resultant molded material is inserted in a heating furnace, and a pressurized gas having a given fluid pressure is fed to the heating furnace. The interior of the heating furnace is heated to a high temperature while applying a static pressure from the outside to the porous glass material 20 to sinter the glass material 20 under heating and give the aimed sintered glass material 22. Preferably, the porous glass material 20 si previously kept in an atmosphere of He to obtain the aimed sintered material 22 of high quality. |
