The preparation techniques of hydrated silica mainly include precipitation method and gas-phase method, which have significant differences in raw materials, processes, and product properties. The precipitation method uses sodium silicate and sulfuric acid as raw materials to generate silica precipitate through acid-base neutralization reaction, which is then washed, dried, and crushed to obtain micrometer sized products. This process has low cost and high production capacity, but the product purity is low (about 93%) and the impurity content is high. It is suitable for fields such as rubber and coatings that do not require high purity.


The gas-phase method uses silicon tetrachloride or trichloromethylsilane as raw materials, which are hydrolyzed at high temperatures in a hydrogen oxygen flame to produce nano-sized particles (particle size 7-40 nanometers). This process produces products with a purity of over 99% and a large specific surface area (200-500 m ²/g), but requires high equipment investment and energy consumption. It is mainly used in high-end fields such as silicone rubber reinforcement, electronic packaging materials, and cosmetic thickeners. For example, the reinforcing effect of gas-phase white carbon black in silicone rubber is significantly better than that of precipitation method, which can increase the tensile strength by more than 300%.