| 摘要 |
PURPOSE:To obtain a heating furnace usable for a long period with little damage e.g. cracking, etc., without forming impurities, by constructing a furnace core tube of the heating furnace for wire drawing of optical fibers from pyrolytic BN. CONSTITUTION:A B halide and N2 or NH3, etc., are reacted in the vapor phase at a temperature as high as >=800 deg.C under <= about 10Torr reduced pressure using C as an ingot mold thereon to form a furnace core tube of pyrolytic BN. The above-mentioned furnace core tube has about >=3,000 deg.C decomposition and sublimation temperature, improved oxidation resistance and high mechanical strength and make it possible to obtain high-strength optical fibers with prevented contaminating sources. |
