| 摘要 |
In the process, a powder element (3), which is doped with fluorine in accordance with a predetermined doping profile and can be sintered to give a clear preform, is produced by depositing SiO2 particles on the outer surface of a cylindrical substrate rod (1) from the combustion flame (2). Known flame hydrolysis is unsuitable for this purpose. Hitherto, undoped powder elements were first produced from SiO2 and subsequently doped with fluorine-containing gases by diffusion during a hydrogen-free drying and sintering process. However, diffusion causes problems. A process is therefore indicated in which the fluorine-diffusion process step is superfluous. To this end, the fluorine-doping is carried out by direct doping of the SiO2 particles during the formation in the hydrogen-free combustion flame and before deposition on the substrate element. <IMAGE> |
