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Fumed silica, also known as pyrogenic silica, is a non-crystalline, fine-grain, low density and high surface area silica. Not to be confused with silica fume, also known as microsilica.
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Properties
Fumed silica has a very strong thickening effect. Primary particle size is 5–50 nm. The particles are non-porous and have a surface of 50–600 m2/g. Density 2.2 g/cm3.
Production
Fumed silica is made from flame pyrolysis of silicon tetrachloride or from quartz sand vaporized in a 3000°C electric arc.[1] Major global producers are Evonik, Cabot and Wacker Chemie-Dow Corning.
Applications
Fumed silica serves as a universal thickening agent, a thickener in milkshakes, and a anticaking agent in powdered foods. Like silica gel, it serves as a desiccant. It is used in cosmetics for its light-diffusing properties. It is used as a light abrasive, in products like toothpaste. Other uses include filler in silicone elastomer and viscosity adjustment in paints, coatings, printing inks, adhesives and unsaturated polyester resins.
Health issues
Fumed silica is not listed as a carcinogen by OSHA, IARC, or NTP. Due to its fineness and thinness, fumed silica can easily become airborne, making it an inhalation risk, capable of causing irritation.
See also
References
- ^ Garrett, P.R. (1992). Defoaming. Theory and Industrial applications. USA: CRC Press. pp. 239–240. ISBN 0-8247-8770-6.
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