| 摘要 |
PROBLEM TO BE SOLVED: To obtain a chamber which is improved in heat resistance and is repetitively usable without the occurrence of cracking and crazing by thermal strain by providing the inside surface of the chamber for production of a porous glass preform with a thermally insulating layer of glass particulates synthesized by flame hydrolysis. SOLUTION: The production of the chamber may be adequately implemented at a thickness of a thermally insulating layer 10 of 0.1 to 10 mm. The production may be implemented even if the glass particulates 6 of the porous glass preform and the glass particulates 6 constituting the thermally insulating layer are the same. The chamber 1 is molded by silica glass. The method for reforming the heat resistance of the chamber 1 is executed prior to the production of the preform and, therefore, a target rod is removed. H2, O2 and SiCl4 (carrier gas Ar) are supplied to a burner 2. When the burner is ignited, SiCl4 is hydrolyzed by an oxyhydrogen flame 3 and the silica glass particulates 6 of SiO2 are synchronized. The inside of the chamber is not evacuated and is, therefore, filled with the silica glass particulates which deposit on the inside wall surface and form the thermally insulating layer 10.
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