Silicon dioxide (SiO2)

SiO2 is the main raw material of glass.

It uses the structure of silicon-oxygen tetrahedron [SiO4] as the skeleton of glass during melting. SiO2 is widely present in nature. Pure SiO2 is colorless and transparent crystal, called "quartz". It is insoluble in water or acid (except hydrofluoric acid), but soluble in alkali. The melting point of SiO2 is 1713℃. Pure SiO2 can be melted into quartz glass at a high temperature of more than 1800℃.

In general glass, SiO2 can reduce the thermal expansion coefficient of glass, increase the viscosity of glass, and improve the thermal stability, chemical stability, softening temperature, mechanical strength and ultraviolet transmittance of glass. However, when the content is too high, a higher melting temperature is required, and crystallization may occur.

The raw materials for introducing silicon dioxide include quartz sand, sandstone, etc.