| 摘要 |
A process wherein, to produce the preform, pulverulent glass starting material is deposited on a substrate by a method in which it is electrostatically charged before the deposition and accelerated toward the substrate surface to be coated by means of a counterelectrode. If the substrate is a rod-shaped substrate (1), which may be made from conductive material, this substrate can itself be used as the counterelectrode. If the substrate is a glass tube whose internal surface is to be coated by deposition of the pulverulent glass starting material, the counterelectrode used is an annular electrode (16) surrounding the glass tube (10). The charging of the particles of the pulverulent glass starting material, which is sprayed onto the surface to be coated, is effected on emergence from a spraying device (2) whose spraying nozzle (3) is connected to a high voltage. After deposition of one or more layers, the material applied is sintered and at the same time electrically discharged. <IMAGE> |
