Fumed silica

Description

A colloidal form of silica that is a very light, fluffy white powder. Fumed silica, also called aerosol silica, is made by hydrogen-oxygen furnace combustion of silicon tetrachloride. This produces tiny spherical particles of varying sizes. Fumed silica is available in hydrophilic and hydrophobic (coated) forms. It is used as a matting agent, thickener, and filler in many adhesives and coatings. Fumed silica has also been used as a desiccating agent to kill insects.

Synonyms and Related Terms

aerosol silica; colloidal silica; pyrogenic silica; thermal silica; Aerosil® [Degussa-Huls]; Cab-O-Sil [Cabot]

Risks

• Inhalation may cause silicosis; used dust mask.
• Integra Chem: SDS

Physical and Chemical Properties

• CAS = 112945-52-5
• Composition = SiO2
• Density = 2.0 - 2.2 g/cm3
• Melting point = 1700 C
• Decomposition = >2000C
• Moisture content = 0.5-2.5 % (Hydrophilic); 0.5% (hydrophobic)
• Adsorbed moisture = 6%
• Refractive index = 1.46
• Particle size = 5-40 nm

Resources and Citations

• Wikipedia: Fumed silica Access July 2023
• George Wypych, 'FILLERS – ORIGIN, CHEMICAL COMPOSITION, PROPERTIES, AND MORPHOLOGY, in Handbook of Fillers (Fourth Edition), 2016Chapter 2.1.79.1 Fumed Silica