Dust-free furnace for drawing optical glass fibre from rod - has tube of monocrystalline zirconium and/or hafnium di:oxide

摘要

Dust-free furnace for optical glass fibre mfr. from a rod-shaped parison has an (in)directly heated tube in which parison is placed without contact and can be melted in a protective gas atmos. This tube of monocrystalline ZrO2, HfO2 or mixed crystals of both. The monocrystals also pref. contain alkaline earth oxide (MgO, CaO or SrO) or lanthanide oxide (Sc2O3, Y2O3 or La2O3) in amts. of 6-50 mole-%. Other oxides can be added in amts. of ca. 1 mole-%. Loosening of oxide particles in the tube is almost completely avoided and the quality of the drawn fibres, esp. their tensile strength, can be increasedconsiderably.