The chemical formula of sodium silicate is Na2O3Si. Sodium silicate, China Academy of Sciences:1344-09-8; 106985-35-7; 1 1 105-00-3; 37299-97- 1; 120 13-79-5, chemical formula: Na2O3Si. Due to the different proportions of sodium oxide and silicon dioxide in molecules, industrial sodium silicate has different properties. The molar ratio of sodium oxide to silicon dioxide is called modulus, the modulus greater than 3 is called neutral sodium silicate, and the modulus less than 3 is called alkaline sodium silicate. Its products are usually divided into solid sodium silicate, hydrated sodium silicate and liquid sodium silicate. Sodium silicate is a colorless, light yellow or blue-gray transparent viscous liquid. It is alkaline when dissolved in water. Colloidal precipitation of silicic acid is precipitated by acid decomposition, which belongs to glassy substance and has no fixed melting point. The modulus of water treatment is 2.5 ~ 3.0. Silicate, as a corrosion inhibitor, was first applied to the corrosion protection of domestic water pipelines. After that, researchers at home and abroad studied and prepared a compound formula with silicate as the main corrosion inhibitor, which further improved the corrosion inhibition performance of silicate. Silicate can form protective films on clean and rusty metal surfaces, but these protective films are porous, so the corrosion inhibition performance of silicate alone is very poor. Silicate is often compounded with polyphosphate, organic phosphate, molybdate, zinc salt and other corrosion inhibitors to play a synergistic role. It has become a new development trend to develop and study silicon-based composite agents. Silicate can not only inhibit the corrosion of steel in cooling water, but also inhibit the corrosion of nonferrous metals-aluminum, copper and their alloys, lead and zinc coatings, and is especially suitable for controlling dezincification of brass. Silicate can effectively prevent the erosion of Cl-, so it can be used as supplementary water for seawater or high Cl- circulating water system. In circulating cooling water, the silicate concentration is 40 ~ 60 mg/L (calculated by Sioz), the concentration is 25 mg/L, and the running pH of Shengjia is 8. o ~ 9.5。 When silicate is used as corrosion inhibitor, there must be enough oxygen in cooling water to effectively protect metals.