Quartz glass is widely used as the outer glass shell material or discharge tube of high-pressure mercury lamps, Xenon Lamps, metal halide lamps, halogen tungsten lamps and germicidal lamps because of its series of advantages.
The fundamental characteristics of quartz glass are high SiO2 content, few impurities, good light transmittance, small thermal expansion coefficient, large resistance, and high viscosity at high temperature.
At present, there are two methods for melting quartz glass: gas refining and electric melting, and the performance varies with the melting method. The purity of quartz glass is very high, and the SiO2 content is generally above 99.9%; the SiO2 content of high-purity quartz is as high as 99.999%, so the chemical stability is very good. The SiO2 content of gas-refined transparent quartz glass is above 99.97%; the SiO? content of electric-melted transparent quartz glass is above 99.95%.
The density of quartz glass is 2.0~2.2g/cm3. The density of transparent quartz glass is
2.21g/cm3, and the content of SiO2 in opaque quartz glass is more than 99.5%. It is made of natural silica and has a milky white appearance. Its density is 2.02~2.18g/cm3.
The mechanical properties of quartz glass are better than those of hard glass and ceramics. Its strength depends on the microcracks in quartz. The finer the crack, the higher the strength, while the coarser the crack, the lower the strength.