Aerosil
Description
[Evonik] A registered trademark for an ultra-fine powdered Silica that was first made in 1942 at Degussa. Aerosil® is a colloidal form of silica that is a very light and fluffy powder. It is made by burning silicon tetrachloride in a hydrogen-oxygen furnace. This produces spherical particles; the particle size can be controlled and varying grades are available ranging in size from 4 to 25 micrometers. The fine particle size provides a high surface area ranging from 35-410 m2/g. Traditional Aerosil® particles (e.g. Aerosil® 300) are hydrophilic and can adsorb water up to 40% of their own weight while still performing as a powder. It is used as a filler, thickener, and as a matting agent in paints. There is also a modified version of Aerosil® (e.g. Aerosil® R7200) that is hydrophopic. It can be added to an aqueous solutions without changing its viscosity. Its water-repellant properties are used to improve corrosion protection of some coatings.
Examples of labeling of Aerosil include:
- Aerosil® 90-380: hydrophilic, fumed SiO2
- Aerosil® R972-R9200: hydrophobic, fumed SiO2 with 0.6-6.5% carbon
- Aerosil® MOX: mixture of SiO2 and Al2O3 used in low viscosity aqueous dispersions
- Aerosil® COK 84: mixture of SiO2 and Al2O3 used to thicken aqueous media
Synonyms and Related Terms
aerosol silica; amorphous fumed silica; hydrophilic silica; fumed silica gel
Applications
- Thickener without opacification
- Defoamer
- Sorbent
Personal Risks
- Inhalation may cause silicosis; use dust mask.
- Particles can irritate eyes.
- CDH Fine Chemical SDS
Collection Risks
- Non-flammable.
- Inert.
Physical and Chemical Properties
- pH = 3.6-4.5
- CAS = 112945-52-5
- Melting Point = 1700 C
- Density = about 2.2 g/ml
- Refractive Index = 1.45
Resources and Citations
- Evonik: History of Aerosil
- Evonik: Aerosil brochure
- G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 709
- Ceramics and Glass Conservation Section, List of Workshop Materials, The British Museum, London
- MSDS Sheet at MFA: old CAS# = 68611-44-9
- www.walsh-assoc.com/continue.html