Fused silica is an amorphous material, characterised by its extremely low co-efficient of thermal expansion and resistance to thermal shock.
Fused silica is produced by melting high purity silica at extremely high temperatures in an electric arc furnace or resistance furnace. It can be solidified and annealed without crystallising due to its extremely high viscosity.
However, it will devitrify at temperatures over 1100 °C.
Optical and general purpose rods are drawn from the melt.
Lowest co-efficient of thermal expansion of any known material.
High resistance to thermal shock
Low thermal conductivity
Excellent electrical insulation up to approximately 1000 °C
Excellent resistance to corrosion from molten metals and glass
Low dielectric constant
Low dielectric loss
Good UV transparency
Easily machined to tight tolerances
Dissolves in hydrofluoric acid (HF)
A filler in electronic encapsulation materials
Optical windows suitable for elevated temperatures