Fumed silica

EN Texto em inglês Ainda não há artigo no teu idioma: trecho em inglês.

Fumed silica (CAS number 7631-86-9, also 112945-52-5), also known as pyrogenic silica because it is produced in a flame, consists of microscopic droplets of amorphous silica fused into branched, chainlike, three-dimensional secondary particles which then agglomerate into tertiary particles. The resulting powder has an extremely low bulk density and high surface area. Its three-dimensional structure results in viscosity-increasing, thixotropic behavior when used as a thickener or reinforcing filler. Fumed silica has a very strong thickening effect. Primary particle size is 5–50 nm. The particles are non-porous and have a surface area of 50–600 m/g. The density is 160–190 kg/m. Fumed silica is made from flame pyrolysis of silicon tetrachloride or from quartz sand vaporized in a 3,000 °C (5,400 °F) electric arc. Major global producers are Evonik (who sells it under the name Aerosil), Cabot Corporation (Cab-O-Sil), Wacker Chemie (HDK), Dow Corning, Heraeus (Zandosil), Tokuyama Corporation (Reolosil), OCI (Konasil), Orisil (Orisil) and Xunyuchem(XYSIL). Fumed silica serves as a universal thickening agent and an anticaking agent (free-flow agent) in powders.