Sometimes referred to as a sol or silica sol, colloidal silica consists of a stable dispersion amorphous silica particles. To achieve this, the silica particles must be small enough such that they are largely unaffected by gravity. Therefore, silica particle sizes are usually of the order of less than 100 nanometres.
The term colloid refers to the suspension, where the sols are the tiny discrete particles in suspension.
Colloidal silica’s can be manufactured from materials such as sodium silicate and are usually available in varying concentrations to suit various applications.
Applications areas include:
• High temperature binders
• Investment casting - used in moulds
• An abrasive - for polishing silicon wafers
• Carbonless paper
• Abrasion resistant coatings
• Increasing friction - used to coat waxed floors, textile fibres 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, stabilising etc