Mandrel for producing quartz glass and production method for optical fiber mother material, optical fiber and quartz glass body using the same

摘要

A mandrel for producing quartz glass, comprising at least two columnar or cylindrical, carbon fiberreinforced carbon composite material made members joined in series by screw thread parts. The mandrel is carbonimpregnated and/or carbon-coated on the screw thread parts, and, in addition, may be provided with reinforcing members on the outer sides of the screw thread parts. Quartz glass fine particles obtained by flame-hydrolyzing a volatile silicon compound are deposited, using this mandrel, on the surface of a heat-resisting substratum or on a starting rod at the end of the mandrel to easily form a large porous quartz glass mother material, the porous quartz glass mother material is dehydrated and transparently vitrified to produce a large optical fiber mother material, and further the optical fiber mother material is drawn to produce a low-cost, high-precision optical fiber. In addition, a columnar or cylindrical mandrel for producing quartz glass is disposed at the center of a heat-resisting mold, is filled with silicon dioxide power, and melt in a heating furnace for vitrifying, thereby producing a large, high precision quartz glass body at low costs.