China Amorphous Fumed Silica SiO2 Powder

Amorphous fumed silica is produced by flame hydrolysis of silicon tetrachloride, resulting in sub‑micron primary particles that fuse into three‑dimensional aggregates. The material is non‑crystalline, high surface area, and exhibits strong reinforcing effects in polymers and resins due to its silanol‑rich surface.

Key Properties

Typical BET surface area ranges from 150 to 250 m²/g, which directly influences viscosity and reinforcement efficiency in elastomers.

Primary particle size, measured by electron microscopy, is usually 5–20 nm, while agglomerate size can vary from 1 to 100 µm depending on grade.

Bulk density (tapped) falls between 40 and 80 kg/m³, allowing low‑loading formulations to achieve significant mechanical improvement.

pH of a 5 % aqueous dispersion is typically 3.5–4.5, reflecting the acidic silanol groups present on the surface.

Loss on ignition (LOI) after heating to 1000 °C is generally below 1.5 %, indicating minimal volatile content.

Typical Industrial Applications

In silicone rubber, fumed silica acts as a reinforcing filler, increasing tear strength and hardness at loadings of 5–20 wt %. The high surface area creates a transient network that resists deformation under strain.

For coatings and inks, the silica provides thixotropic control, preventing sagging while maintaining low viscosity during application. Typical addition levels are 0.5–2 wt % depending on desired rheology.

Adhesives and sealants benefit from improved green strength and reduced shrinkage; the silanol groups can react with coupling agents to enhance interfacial bonding to substrates.

In polymer composites such as epoxy or polyurethane, fumed silica improves modulus and thermal stability while acting as a nucleating agent that can reduce cure time.

Technical Specifications

Quality Assurance and Testing

Each batch is sampled for surface area, particle size, and LOI using calibrated instruments. Results are recorded against internal specifications and a certificate of analysis is provided with every shipment.

Traceability is maintained through batch numbers linked to raw material lots and production parameters (flame temperature, residence time, SiCl4 flow). This enables root‑cause analysis if performance deviations arise.

We follow ISO 9001‑based procedures for in‑process control, including hourly monitoring of reactor temperature and exhaust particle counts to ensure product consistency.

Packaging, Handling, and Storage

The powder is packed in multi‑layer polyethylene bags with an inner moisture‑barrier liner, then placed in corrugated cartons or on pallets. Net weights are typically 10 kg or 25 kg per bag, customized per customer request.

To prevent moisture uptake, store in a dry environment below 30 °C and keep bags sealed until use. Properly stored material retains its specified surface area for at least 24 months.

During handling, use dust‑control measures such as local exhaust ventilation or protective respirators, as fine silica can become airborne.

Frequently Asked Questions

• Can the particle size or surface area be tailored? Yes, flame‑hydrolysis parameters can be adjusted to produce grades with specific BET values or agglomerate sizes; consult our technical team for feasibility.
• What information is needed for a quotation? Required details include desired grade (surface area range), quantity, packaging preference, delivery destination, and any special certification needs.
• How is quality verified? Each lot ships with a certificate of analysis showing BET, LOI, pH, and tapped density, tested per ASTM or ISO standards.
• What lead times are typical? Standard production lead time is 2–3 weeks after order confirmation; express options are available upon request.

Get Technical Support and Quotation

For further details, sample requests, or to discuss a custom specification, please contact our engineering team.