Which is better, fumed silica or precipitated silica? How to distinguish?

1、 What is silica?

Silica is a product of white amorphous powder silicate and silicic acid, also known as fumed silica. According to the production process of silica, silica is divided into precipitated silica and fumed silica.

2、 Fumed silica

The fumed silica is a kind of amorphous silica product produced by the hydrolysis of halosilane at high temperature. It is a multifunctional additive that has the functions of reinforcing, thickening, anti-precipitation and extinction; Generally, fumed silica can be divided into hydrophilic silica and hydrophobic silica. The following are the characteristics of fumed silica:

(1) High temperature resistance

(2) Incombustible

(3) High electrical insulation

Physical parameters

Particle SizeBETSiO2 Content

Applied fields: silicone rubber, coating, rubber, chemical mechanical polishing etc.

3、 Precipitated silica

Precipitated silica, also known as precipitated hydrated silica, is made of quartz sand, soda ash, industrial sulfuric acid, etc. Its main component is SiO2. The performance of precipitated silica is similar to that of carbon black, and its appearance is white and highly dispersed amorphous or flocculent powder. The following are its features:

(1) It is insoluble in water and most acids, but soluble in caustic soda and hydrofluoric acid.

(2) Chemical properties are stable. High temperature resistance, not easy to decompose and not burning

(3) High electrical conductivity

(4) High dispersion, porosity and large specific surface area

(5) High reinforcement.

Physical parameters:

Particle SizeRelative DensityMelting Point

Application: rubber tire, paint, toothpaste and other additives

4、 Difference between fumed silica and precipitated silica

ItemFumed SilicaPrecipitated Silica
Particle Size7-40mm, and agglomeration will occur. It has strong adsorption capacity≤0.3um
Silicohydroxy GroupHydrophilic type:2-36
Fineness>1000 mesh300-400 mesh
SiO2 content>99.8%>95.0%

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