Large Scale Fluoride Glass Synthesis

An RF heated, bottom drain furnace/crucible assembly capable of melting up to 1 liter (z4.3 kg) of fluorozirconate glass is described. The apparatus was used in conjunction with gas and oil cooled molds to prepare glass discs of the ZBLAN composition z13 cm in diameter with thicknesses of z1.2-2.5 cm. Mathematical modelling of the thermal conditions associated with the fabrication of large castings was also carried out. These calculations were used to examine the limits on casting thickness and develop engineering designs for molds capable of producing large crystal and crack-free discs.