Silica, Quartz and Silicate Materials

Silica, quartz and silicate materials include fused silica, quartz, kaolin or clay-based materials, cordierite, steatite, forsterite, sillimanite, zircon, porcelain, and fireclay. Silica and silicate are based on silicon dioxide and various chemical variations of this material. Aluminum, calcium, sodium, and magnesium oxide additions can modify properties and processing characteristics. Silica, quartz and silicate materials are available in fused and cast glassy forms such as common silicate glass, sintered or fired polycrystalline silica, and single crystal quartz. With single crystal or monocrystal materials, the crystalline framework is homogenous. By contrast, polycrystalline materials are composed of a number of smaller, heterogeneous crystals or crystallites.

There are many different types of silica, quartz and silicate materials. Chemical variations and processing techniques are used to produce specific types such as aluminum silicate, calcium silicate, clay, cordierite, fireclay, forsterite, and kaolin. Aluminum silicate is insoluble and often used as a refractory in glassmaking. Calcium silicate is used as both an anti-caking agent and as an antacid. Clay is a very fine-grained soil that is plastic when moist and hard when fired. Cordierite is used in ceramic products such as catalytic converters. Fire clay and other refractory clays are also resistant to high temperatures. Kaolin or china clay is a fine, usually white clay that is used in ceramics and as an absorbent. Forsterite is also grouped with silica, quartz, and silicate materials.

Types of silica, quartz and silicate materials include magnesium silicate, mica, mullite, porcelain, sillimanite, steatite, and zircon. Magnesium silicate is used in a variety of applications, including as a food additive and to resist crazing. Mica is a mineral with thin, tough, and flexible flakes. Mullite is used for refractory tubes, industrial crucibles, analytical labware, dielectric substrates, wear components and in refractory cements. Porcelain is made by heating silica, quartz, and silicate materials such as kaolin. Sillimanite is used in the glass industry. Steatite ceramics may have additions of alumina, calcia and ferrous oxide.  Zircon is a compound of a zirconium silicate, which is found naturally in the form of zircon sand.

Silica, quartz and silicate materials can be varied to enhance optical properties such as clarity and transparency.  Their dielectric or electrical insulating properties is enhanced with variation compositional changes and processing conditions. Silica, quartz and silicate materials are used in optical, thermal, chemical, and electrical and electronics applications.

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