Redir: Silica

The chemical compound silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with a chemical formula of Oxygen: 2 and has been known for its hardness since antiquity. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms. It is a principal component of most types of glass and substances such as concrete. Silica is the most abundant mineral in the earth's crust.

Manufactured forms

• Glass (a colorless, high-purity form is called fused silica)
• Synthetic amorphous silica, silica gel
• Fumed silica (also known as pyrogenic silica, colloidal silica, or under the genericized trademark, Cab-o-Sil)
• Precipitated silica is produced by precipitation from a waterglass solution by acidification.
• Silica aerogel.

Applications

It is used in the production of various products.

• Inexpensive soda-lime glass is the most common and typically found in drinking glasses, bottles, and windows.
• A raw material for many whiteware ceramics such as earthenware, stoneware and porcelain.
• A raw material for the production of Portland cement.
• A food additive, primarily as a flow agent in powdered foods, or to absorb water (see the ingredients list for).
• The natural ("native") oxide coating that grows on silicon is hugely beneficial in microelectronics. It is a superior electric insulator, with high chemical stability. In electrical applications, it can protect the silicon, store charge, block current, and even act as a controlled pathway to allow small currents to flow through a device. At room temperature, however, it grows extremely slowly, and so to manufacture such oxide layers, the traditional method has been heating of silicon in high-temperature furnaces within an oxygen ambient (thermal oxidation).
• Raw material for aerogel in the Stardust spacecraft
• Used in the extraction of DNA and RNA due to its ability to bind to the nucleic acids under the presence of chaotropes.
• As hydrophobic silica it is used as a defoamer component.
• As hydrated silica in toothpaste (abrasive to remove plaque.)
• As a high-temperature thermal protection fabric.
• In cosmetics for its light-diffusing properties and its absorbency.
• Liquid silicon dioxide (colloidal silica) is used as a wine and juice fining agent.
• As a glidant in pharmaceutical products silicon dioxide aids powder flow when tablets are formed.
• In the production of tires
• Thermal enhancement compound used in thermal grouts for the ground source heat pump industry.

Inhalation health effects