Hydrophilic/Hydrophobic Fumed Silica

🔬 Product Overview

Fumed Silica is a high-purity, nano-sized amorphous silicon dioxide synthesized via a high-temperature vapor phase hydrolysis process. The most typical production method involves vaporizing and hydrolyzing silicon tetrachloride in a hydrogen-oxygen flame (at approximately 1800°C). The resulting silicon dioxide molecules aggregate into primary nanoparticles, which further collide and fuse in the high-temperature gas stream, forming three-dimensional, chain-like aggregates. This material possesses an extremely high specific surface area, nanoscale particles, and a surface rich in silanol groups, granting it exceptional functionalities such as reinforcement, thickening, thixotropy, and anti-settling.

Based on surface properties, fumed silica is primarily categorized into two main types:

⚙️ Key Performance Parameters

Understanding the following key parameters is crucial for correct selection:

✨ Functional Characteristics

The core value of fumed silica lies in its multifunctionality:

· Efficient Thickening and Thixotropic Action: This is one of its most classic applications. In liquid systems like resins, coatings, and adhesives, the 3D network structure of fumed silica forms a weak network via hydrogen bonding, thickening the system. Under shear force (e.g., stirring, brushing), this network breaks down, reducing viscosity; when the shear force is removed, the network quickly recovers, and viscosity increases. This is thixotropy (shear-thinning), which effectively prevents the settling of pigments and fillers and prevents sagging on vertical surfaces during application.

· Exceptional Reinforcing Performance: In elastomers like silicone rubber, fumed silica is an indispensable reinforcing filler. It significantly enhances the tensile strength, tear strength, and abrasion resistance of the vulcanizate, far exceeding the reinforcing effects of other mineral fillers.

· Excellent Anti-caking and Dispersion Properties: It helps powder particles (e.g., in food, pharmaceuticals) remain free-flowing and prevents caking; in liquids, it promotes the dispersion and suspension of solid particles, maintaining system stability.

· Other Characteristics: Include chemical inertness, high-temperature resistance, excellent electrical insulation (even in humid environments), and the ability to function as an adsorbent and carrier.

🏭 Main Application Fields

Fumed silica finds applications across nearly all modern industries:

📝 Usage Guidelines

To fully leverage the performance of fumed silica, please note the following:

· Dispersion is Key: Appropriate high-shear dispersion equipment (e.g., high-speed dispersers, ball mills, three-roll mills) is essential to ensure thorough dispersion and the formation of a uniform network structure.

· Correct Addition Method: It is recommended to add the powder slowly to the liquid under continuous agitation to prevent the formation of difficult-to-disperse "fish eyes" (lumps).

· Match the System: Hydrophilic types are suitable for aqueous and many polar systems; Hydrophobic types are specifically designed to improve compatibility and performance in organic solvents, silicone rubber, and highly polar resins (like epoxy, polyurethane).

· Typical Addition Levels: Common addition levels range from 0.5% to 3%, with the specific amount to be determined experimentally. Excessive addition can lead to a sharp viscosity increase or over-thickening.

🏷️ Packaging & Storage

· Packaging: Standard packaging is 10 kg/bag in plastic-lined woven bags. Other specifications can be provided according to customer requirements.

· Storage Conditions: Must be stored in the original, sealed container in a cool, dry warehouse, strictly protected from moisture. Under correct storage conditions, the shelf life is typically 24 months.

💎 Summary

Thanks to its unique nanostructure and surface chemistry, fumed silica serves as a key "high-impact" component in many high-end products and processes. Correctly selecting between hydrophilic or hydrophobic types and mastering their dispersion and application techniques are central to successfully using this material.

We hope this professional introduction adds value to your website. If you require more detailed information tailored for specific applications (e.g., specific grade recommendations for silicone rubber or coatings), we are ready to provide further assistance.