According to the properties of the introduced oxides, it can be divided into acid oxide raw materials, alkali metal oxide raw materials and alkali earth metal oxide raw materials.
① Acid oxide raw materials: there are SiO2, B2O3, Al2O3 and other raw materials. SiO2 is the skeleton of the glass structure in silicate glass. It gives the glass height, good chemical stability, heat resistance and low expansion, but it will increase the melting temperature of the glass and increase the viscosity. The quoted raw material of SiO2 is silica sand or sandstone and quartzite. Adding B2O3 to glass can reduce the thermal expansion of glass, improve the refractive index, heat resistance and chemical erosion resistance, reduce the viscosity of glass at higher temperatures, and improve the viscosity of glass at lower temperatures. The quoted raw material for B2O3 is borax or boric acid. Adding Al2O3 to glass can reduce the glass crystallization tendency and enhance the chemical stability, improve the degree, and increase the glass viscosity. The quoted raw material is usually feldspar with K2O or Na2O and SiO2, and industrial alumina can also be used. Cangzhou Tianchang technology glass products factory has experience in producing various types of high borosilicate glass tubes
② Alkali metal oxide raw materials: Na2O, K2O raw materials. The addition of Na2O and K2O to the glass can reduce the melting temperature and viscosity, but it will make the chemical stability of the glass worse. The quoted raw materials are soda ash (Na2CO3) and potassium alkali (K2CO3).
③ Alkaline earth metal oxide raw materials: there are CaO, MgO, BaO, ZnO, PbO raw materials. Adding CaO and MgO to glass can weaken the crystallization tendency of sodium-silicon glass, enhance the chemical stability, reduce the viscosity of glass at high temperature, and promote the melting and clarification of glass, but the viscosity increases quickly when the temperature decreases, and the molding operation is difficult. The quoted raw materials are limestone (CaCO3) and magnesite (MgCO3), or dolomite containing both CaO and MgO. BaO and ZnO are often added to the glass to adjust the chemical stability and refractive index of the glass, and the quoted raw materials are often industrial ZnO and BaCO3, BaSO4 or Ba(NO3)2. The addition of PbO in glass can significantly improve the refractive index and dispersion, so that the glass can absorb short-wavelength rays, at the same time, the specific gravity is increased, the melting temperature is reduced, and the metal infiltration is good. The quoted raw materials for PbO are red lead and yellow lead or industrial lead nitrate.
In addition, broken glass is also a main raw material, often called clinker, can melt at a lower temperature, contributing to the melting of glass compounds