Quartz glass is a special industrial glass made of silica. It is a very excellent material. Quartz glass has a series of excellent physical and chemical properties: 1. High temperature resistance. The softening point temperature of quartz glass is about 1730 ℃, which can be used at 1100 ℃ for a long time and 1400 ℃ for a short time. 2. Corrosion resistance. Except hydrofluoric acid, quartz glass hardly reacts with other acids, especially its chemical stability at high temperature, which is unmatched by any other engineering materials. 3. Good thermal stability.
The coefficient of thermal expansion of quartz glass is very small and can withstand drastic temperature changes. If the quartz glass is heated to about 1100 ℃, it will not burst in normal temperature water. 4. Good light transmittance. Quartz glass has good light transmission performance in the whole optical band from ultraviolet to infrared, and the visible light transmittance is more than 95%, especially in the ultraviolet spectral region, the large transmittance can reach more than 90%. 5. Good electrical insulation. The resistance of quartz glass is 10000 times that of ordinary glass. It is an excellent electrical insulating material and has good electrical properties even at high temperature. Because of the above excellent physical and chemical properties, quartz glass is widely used in electric light source, semiconductor, optical communication, military industry, metallurgy, building materials, chemistry, machinery, electric power, environmental protection and other fields.
In addition, the expansion coefficient of quartz glass is very small, which is one fourteenth of that of ordinary flat glass. Quartz glass is not afraid of rapid cooling and heating. It will not burst when heated to 900 ℃ and then put into cold water.
Quartz glass is divided into linear expansion and bulk expansion. The expansion and contraction curves of quartz glass are congruent. Reversible temperature resistance and hot blood performance of quartz glass is one of the important properties of quartz glass. The high temperature resistance of quartz glass is far better than any kind of glass. Its melting temperature is above 1713 ℃, softening temperature is 1580 ℃± 10 ℃, and annealing temperature is 1140 ± 20 ℃. Quartz glass can withstand a high temperature of more than 1000 ℃ and can be used at a high temperature of 1450 ℃ in a short time. For use at high temperature, opaque quartz glass can be used at 900 ℃.
Quartz glass has particularly good light transmittance in the whole wavelength. In the infrared region (except for special infrared glass), the spectral transmission range is larger than that of ordinary glass. In the visible spectral region, the transmittance is 93%. In the ultraviolet spectral region, especially in the short wave ultraviolet spectral region, the transmittance is much better than other glasses. The optical properties of quartz glass largely depend on its chemical purity. Even 0.001% impurities will significantly affect the product quality. The content of transition metal impurities will change the wavelength and move to the long wave direction, and the presence of hydroxyl will absorb 2.73 μ M light band. There are three brands of domestic optical quartz glass: JGS1 far ultraviolet optical quartz glass, application band 185-2500 μ m. It is made of synthetic quartz with SiCl4 as raw material; Jgs2 UV optical quartz glass, application band 220-2500 μ m. Using crystal as raw material, it is produced by gas refining method; Jgs3 infrared optical quartz glass, application band 260-3500 μ m. Using crystal or high-purity quartz sand as raw material, it is produced in vacuum pressurized furnace.