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Encyclopedia > Fused silica

Fused quartz is a man-made material manufactured principally from sands. It is non-crystalline, and in a high purity state is a useful material for high performance fluid and gas delivery. Its mechanical and thermal properties are superior to that of glass due to its purity [or rather, its lack of impurities]. For these reasons, it finds use in situations such as semiconductor fabrication and laboratory equipment.

The name quartz comes from the mineral of the same basic chemical composition. The natural material is crystalline.

The chemical name of fused quartz is silicon dioxide, which is also called silica. This material was originally called fumed silica because the high purity manufacturing process involves chemical gassification of silicon, oxidation of this gas to silicon dioxide, and thermal fusion of the resulting dust. From this final melting process it also gets the name fused silica.

The extremely low coefficient of thermal expansion accounts for its remarkable ability to undergo large, rapid temperature changes without cracking.

Fused silica is transparent to ultraviolet light and near infrared light, and has many uses in technical optics as a consequence.

Specially prepared fused silica is also the key starting material used to make optical fiber for telecommunications.

Because of its strength and high melting point (compared to ordinary glass), fused silica is used as the envelope of halogen lamps, which must operate at a high envelope temperature to achieve their combination of high brightness and long life.

The combination of strength, thermal stability, and UV transparency makes it an excellent substrate for projection masks for photolithography.

See also: quartz, list of minerals

Properties of Clear Fused Quartz

(Based on information in Fused Quartz Catalogue Q-7A, General Electric Company)

  Results from FactBites:
Fused quartz - Wikipedia, the free encyclopedia (771 words)
Fused silica is produced using high purity silica sand as the feedstock, and is normally melted using an electric furnace, resulting in a material that is translucent or opaque.
Synthetic fused silica is made from a silica-rich chemical precursor usually using a continuous flame hydrolysis process which involves chemical gassification of silicon, oxidation of this gas to silicon dioxide, and thermal fusion of the resulting dust (although there are alternative processes).
Fumed silica is manufactured by a similar flame hydrolysis process to synthetic fused silica, however is in the form of a fine powder/dust and is typically used in applications such as fillers for rubbers and plastics, coatings, adhesives, cements, sealants, cosmetics, pharmaceuticals, inks and abrasives.
Silica – Silicon Dioxide (SiO2) (1410 words)
Fused is primarily used in the electronics industry (around 70% of the total market) where its good dielectric and insulating properties are exploited; though it may also be used as a refractory material or in investment casting.
Fused silica is used in the refractory casting slurry, where it coats a wax replica of the component to be cast.
Silica is commonly used as a filler in paints, plastics, rubber, adhesives, putty and sealants.
  More results at FactBites »



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