Fume Silica

Hydrophilic Fume Silica

This chemical materials supplier product, the hydrophilic fume silica is made by combusting silicon tetrachloride vapour with oxygen and hydrogen. Being vapour based it readily disperses into liquid or powder to very fine particle size. The fine particle size provides excellent dispersion properties when combined with other materials such as silicon rubber. Fume silica provides highly thickening property and thixothropy to liquid medium.

Thixotropy is a characteristic property that liquid varies in its viscosity, in that the liquid flows well when sprayed or brushed but reverses to highly viscous state again when it is left at rest.

Fume silica can also be used as an anti-sagging or anti-settling agent for heavy pigments.

Because of its extra fine particle size and excellent dispersion properties, a thickened liquid using fume silica still retains excellent transparency. Very usefully used as transparent matting agent and anti-slipping agent for transparent plastic films.

It also improves the free-flowing property and anti-caking property of powder products when small addition of fume silica is added as part of the ingredient.

Fume silica is synthesised at a high temperature and it is anhydrous when manufactured. Even with the high temperature used during manufacturing, it still retains its original properties of the base material. Fume silica is rather chemically inert. It improves dielectric property; it is weather proof and has good heat resistance.

Typical properties of fume silica, it has a specific surface area of 50-500m2/g and consists of particles of 5-50mµ which are smaller than any other spherical particles contained in powders ever found.

Typical application of fume silica, it is used as reinforcement, improvement of di-electric properties, as thickener, anti-blocking, anti-slipping, thixotropy, anti-settling of heavy pigment, anti-sagging free flow agent and anti-caking, etc. It is use in many products like silicone rubber, silicone oil, synthetic rubber and resin, plastic film, paints and printing inks in coating applications, unsaturated polyester resin, sealants, adhesives, paper, pharmaceuticals and food, cosmetics, waxes, lubricants and polishes, toners and in the electric industry.

Footnote: Silica Fume vs Fume Silica.

Just a difference in word positioning could mean a whole lot of difference! The explanation above refers to Fume Silica used for thyrotrophic effect for various applications such as coatings and unsaturated polyester production. While Silica Fume is another type of silica material used in construction industry as part of the supplementary cementing materials or mineral admixtures formulation for hardening of concrete via hydraulic or pozzolanic activity.

Silica fume — also known as condense silica fume or microsilica — is a finely divided residue that came about from the production of elemental silicon or ferro-silicon alloys that was carried from the furnace by the exhaust gases. The production process is very much different from Fume Silica or more accurately called hydrophilic fume silica which is made from the combustion of silicon tetrachloride vapour with oxygen and hydrogen. The pricing is also much different with Fume Silica costing about 5 times more than Silica Fume!

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