Chemical vapor deposition
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Chemical vapor deposition is also known as dry or pyrolysis. Its primary particle size is between 7 and 40 nm. The specific surface area is generally greater than 100m2 / g, and the silica content is not less than 99.8%. Generally, silicon tetrachloride gas is used to perform high-temperature hydrolysis in a mixed gas stream of hydrogen and air to synthesize silica aerosol, and then perform aggregation, cyclone separation, and deacidification.
Gas-phase preparation of silica is the main method for preparing nano-scale silica. The white carbon black product prepared by this method has high purity, large specific surface area, good dispersion, and fine and spherical particles. The disadvantages are high equipment requirements, complex technology, expensive raw materials, and large investment scale.
