Silica
Description
Silica (CAS 7631-86-9), also known as silicon dioxide or SiO2, is a high-purity amorphous mineral used across industrial and consumer product manufacturing. As E551 in food-contact and additive applications, it functions primarily as an anticaking agent.
It serves as a flow aid and rheology modifier in powder and liquid systems. In personal care, silica controls texture and oil absorption in pressed powders, dry shampoos, and skincare formulations where sensory performance and spreadability are critical.
Rubber and tire compounding relies on precipitated silica as a reinforcing filler that improves rolling resistance and wet grip performance in high-performance tire compounds. Plastics and polymer processing uses fumed silica to modify viscosity.
This application is vital in adhesives, sealants, and coatings, preventing sagging and improving shelf stability. In printing and packaging, silica acts as a matting agent and anti-slip additive in inks and surface coatings.
Silica is supplied as fumed silica, precipitated silica, and colloidal silica dispersions, each suited to different processing requirements. Standard grades include food-grade (FCC, E551) and pharmaceutical-grade options.
These pharmaceutical grades meet USP and Ph. Eur. standards, alongside technical-grade for industrial applications. Particle size, surface area, and surface treatment vary by grade and determine suitability.
Hydrophilic or hydrophobic treatments are available depending on specific formulation or processing conditions. This versatility ensures that the material meets the rigorous demands of diverse global manufacturing sectors.
Physical Properties
| Melting Point | 1713 °C |
| Boiling Point | 2230 °C |
| Density | 0.729 g/cm³ (solid) |
| Flash Point | 2230°C |
| Appearance | Amorphous silica, the noncrystalline form of SiO2, is a transparent to gray, odorless, amorphous powder |
| Color | White to yellow |
| Odor | at 100.00?%. odorless |
| Form | suspension |
| Water Solubility | insoluble |
| Vapor Pressure | 13.3hPa at 1732℃ |
| Refractive Index | 1.46 |
| pH | 5-8 (100g/l, H2O, 20℃)(slurry) |
Safety & Handling (Learn More)
Trade & Regulatory
| HS Code | 2811221000 |
| Storage Class | 12 - Non Combustible Liquids |
| WGK (Germany) | nwg |
Documentation
Other Names
silicic anhydride|silicon oxide|SILICON DIOXIDE|Diatomaceous silica|Wessalon|Zorbax sil|Silica, amorphous|Silica, colloidal|SiO2|E220A
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