There's no difference between fumed silica and precipitated silica. The chemical names are silicon dioxide. However, the gas-phase process uses silicon tetrachloride and air-fired silicon dioxide with a fineness of more than 1000 mesh, while the precipitation process uses sodium silicate to precipitate the silicon dioxide with sulfuric acid. The fineness is only 300-400 mesh. The silica produced by fumed silica is expensive and does not absorb moisture easily. Used as a matting agent in paint. Precipitated silica is cheap and easy to absorb moisture. Can only be used in rubber, plastic products filled, reinforced.
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