Fused Silica is an amorphous siliceous glass produced by high temperature fusion of high quality crystalline silica (quartz). The fusion produces a substance characterised by very low thermal expansion and a high resistance to temperature and thermal shock.

Fused Silica is employed in a variety of industrial applications including foundry (investment casting slurry and stucco, and mould release agent), refractory and ceramic (crucibles, saggars, rollers, pouring cups, ceramic cores, gas fire radiants and items for steel, non-ferrous metal and glass industries), and filler (electronic and adhesive).

Typical Chemical Composition

Fusing aluminous raw materials electrically in an electric arc furnace can produce fused alumina. The fused product is then cooled into ingots, crushed and then classified. There are two types of fused alumina – white and brown.

White Fused Alumina is formed from calcined alumina. The only impurity in fused alumina is sodium, which is present in the form of alpha-alumina. Fused alumina, with its perfect crystallisation is difficult to sinter. It is inactive and does not readily react with other raw materials. Fused aluminas tend to be used in refractories which are exposed to very severe conditions.

Brown Fused Alumina is manufactured from bauxite. Its impurities are reduced to precipitate as Fe-Si-Ti system iron alloys, but some of the titanium forms a solid solution with alumina. This causes the brown colour of the material.

Fused Alumina has a very high degree of toughness and can be used to produce high purity refractory shapes and monolithics, investment casting shells and for abrasive applications.

Typical Chemical Composition

Zirconium and Yttrium Oxides

Speciality powders used in investment casting of titanium/alloys

Used as an additive to control the microstructure of turbine blades and medical instrument investment castings. Contact the office for further information.