Fumed Silica Size & Property

Fumed silica (CAS number 112945-52-5), also known as pyrogenic silica or colloidal silicone dioxide, is produced through flame hydrolysis synthesis in which silicon tetrachloride reacts with hydrogen & oxygen, and the SiO2 seed grows in size or aggregates.


Fumed silica is produced at small particle sizes (around 7-40 nanometers), which makes it very reactive and gives it more surface area for chemical reactions. It’s porous-structure powder.

Property of HIFULL Hydrophilic Fumed Silica

  • Partical Size: Primary 7-20nm
  • Aggregates (average):150-300nm
  • Agglomerates( average ): 1-50um
  • Specific surface area (BET): 90-400 m2/g
  • Tamped density: 40-120 g/l
  • pH in 4% dispersion: 3.7-4.5
  • Purity: SiO2 Content> 99.8%
  • Sieve residue (45um): < 0.025%
  • Loss on drying: < 0.5-1.5% @ 105℃/2h
  • Loss on ignition: < 1% @1000℃/2h
  • Crystal structure: amorphous
  • Refractive index: 1.46
  • Specific gravity: 2.2g/cm3

Property of HIFULL Hydrophobic Fumed Silica

  • Surface Chemistry: surface silanol group( Si-OH) was reacted, show hydrophobicity; Low Moisture absorption
  • Particle Size:treated based on hydrophilic fumed silica, increase of particle size accordingly
  • Specific surface area (BET): 90-400 m2/g
  • Tamped density: 40-120 g/l
  • pH in 4% dispersion: 3.0-10
  • Carbon Content: 0.5%-6%
  • Sieve residue (45um): < 0.025%
  • Loss on drying: < 0.1-1.5% @ 105℃/2h
  • Loss on ignition: < 1% @1000℃/2h
  • Crystal structure: amorphous
  • Refractive index: 1.45-1.46
  • Specific gravity: 2.2g/cm3

Fumed Silica functions

Fumed silica has better performance in thickening, thixotropy, sag resistance, reinforcement and caking resistance. While precipitated silica is mainly used as a reinforcing agent for rubbers or friction agent in toothpaste.

Fumed SilicaVSPrecipitated Silica
150-300 Nano meter AGGREGATES SIZE    1-100 Micron meter
90-400㎡/gSPECIFIC SURFACE AREA50-600 ㎡/g
Fumed silica is synthesized from the hydrolysis of high purity silane in a flame of oxygen and hydrogen at a very high temperature.  MANUFACTURING PROCESSPrecipitated silica is produced by the Controlled neutralization of dilute sodium silicate (water glass) by either concentrated sulfuric, hydrochloric or carbonic acids. 
High specific surface area, small particle sizeFEATURELow specific surface area, large particle size
Has better performance in thickening, thixotropy, sag resistance, reinforcement, caking resistance; mainly used for industries that need high transparency, high purity & small surface area.FUNCTIONSPrecipitated silica is mainly used as natural rubber and synthetic rubber reinforcing agent, friction agent in toothpaste. 
Competitive price with international brandPRICELower than fumed silica

HIFULL manufactures more than 10 grades of hydrophilic and hydrophobic fumed silica for your special choice. For product TDS, MSDS or sample-testing, price quotation, please check Datasheet or leave message to us.

Hello, Customers

My name is Van, I’m the business manager of HIFULL, I have been in Fumed Silica Industry for more than 10 years. Feel free to contact me. I’m happy to provide you the best service and products.
Business Manager