Colloidal Silica

Colloidal silicas are suspensions of fine amorphous , nonporous, and typically spherical silica particles in a liquid phase. Usually they are suspended in an aqueous phase that is stabilized electrostatically. Colloidal silicas exhibit particle densities in the range of 2.1 to 2.3 g/cm 3 . Most colloidal silicas are prepared as monodisperse suspensions with particle sizes ranging from approximately 30 to 100 nm in diameter. Polydisperse suspensions can also be synthesized and have roughly the same limits in particle size. Smaller particles are difficult to stabilize while particles much greater than 150 nanometers are subject to sedimentation.

Typical Applications:
* In papermaking colloidal silica is used as a drainage aid. It increases the amount of cationic starch that can be retained in the paper.
* High temperature binders
* An abrasive - for polishing silicon wafers
* Carbonless paper
* Catalysts
* Moisture Absorbent
* Stabilizing and rigidizing refractory ceramic fiber (fiberfrax) blankets
* Abrasion -resistant coatings
* Increasing friction - used to coat waxed floors, textile fibers and railway tracks to promote traction
* Antisoiling – fills micropores to prevent take up of dirt and other particles into textiles
* Surfactant – used for flocculating , coagulating , dispersing , stabilizing etc.
* Liquid silicon dioxide (colloidal silica) is used as a wine and juice fining agent .
* Absorbent
* Colloidal silica is used in concrete densifiers and polished concrete.