Quartz glass, with its excellent physical and chemical properties, is widely used in various fields such as semiconductor technology, new electric light sources, production of color TV phosphors, chemical processes, ultra-high voltage dust collection, far-infrared radiation heating equipment, aerospace technology, optical systems for certain weapons and optical instruments, atomic energy technology, refractory materials for float glass and alkali glass cellars, crucibles for special glass, material bowls for instrument glass forming parts, ultraviolet sterilization lamps, and production of various non-ferrous metals. Quartz glass has a SiO2 content greater than 99.5%, a low coefficient of thermal expansion, high temperature resistance, good chemical stability, transparency to ultraviolet and infrared light, high melting temperature, high viscosity, and difficult molding. Widely used in semiconductor, electric light source, optical communication, laser and other technologies and optical instruments.
Quartz glass has particularly good transparency throughout the entire wavelength, and in the infrared region (except for special infrared glass), the spectral transmission range is larger than that of ordinary glass. The transmittance in the visible light range reaches 93%. In the ultraviolet spectral region, especially in short waves, the transmittance in the ultraviolet spectral region is much better than other glasses. The optical properties of quartz glass largely depend on its chemical properties. Even 0.001% impurities significantly affect product quality. Excessive metal impurities can shift the wavelength direction, and the presence of hydroxyl groups can absorb the 2.73 µ m light band. There are three grades of domestically produced optical quartz glass: JGS1 ultraviolet optical quartz glass, used in the wavelength range of 185-2000nm, made of synthetic stone with Sicl4 as raw material, JGS2 ultraviolet optical quartz glass, used in the wavelength range of 220-2500nm, made of crystal as raw material, produced by gas refining method; JGS3 infrared optical quartz glass, applied in the wavelength range of 260-3500nm, is produced using crystal or high-purity quartz sand as raw materials in a vacuum pressure furnace. There is also a type of full band optical quartz glass abroad, which is used in the wavelength range of 180-4000nm and produced by plasma (in an anhydrous and H2 free state) chemical deposition method. Using high-purity Sicl4 as raw material. Adding a small amount of TiO2 to quartz glass can filter out ultraviolet radiation at 220nm, which is called ozone free quartz glass. Because ultraviolet radiation below 220nm can convert oxygen in the air into ozone, a small amount of elements such as titanium and europium can be added to quartz glass. Short waves below 340nm can be filtered out. Using it to produce electric light sources has a health promoting effect on human skin. This type of glass can achieve complete absence of bubbles. It has excellent ultraviolet transmission performance, especially in the short wave ultraviolet region, and its transmission performance far surpasses all other glasses. The transmittance at 185 µ m can reach 85%. It is an excellent optical material in the 185-2500nm wavelength range. Due to the presence of OH groups in this type of glass, its infrared transmission performance is poor, especially with a large absorption peak around 2.7 µ.
Quartz glass has a series of excellent physical and chemical properties, such as:
1. High temperature resistance. The softening point temperature of quartz glass is about 1730 ℃, and it can be used for a long time at 1100 ℃. The maximum temperature for short-term use can reach 1450 ℃,
2. Corrosion resistance. Except for hydrofluoric acid, quartz glass hardly undergoes chemical reactions with other acidic substances. Its acid resistance is 30 times that of ceramics and 150 times that of stainless steel. Especially in terms of chemical stability at high temperatures, it is incomparable to any other engineering material.
3. Good thermal stability. The thermal expansion coefficient of quartz glass is extremely small, and it can withstand drastic temperature changes. Even when heated to around 1100 ℃ and placed in room temperature water, quartz glass will not explode.
4. Good transparency performance. Quartz glass has good transparency in the entire spectral range from ultraviolet to infrared, with a visible light transmittance of over 93%, especially in the ultraviolet spectral region, where the maximum transmittance can reach over 80%.
5. Good electrical insulation performance. The resistance value of quartz glass is equivalent to ten thousand times that of ordinary glass, making it an excellent electrical insulation material with good electrical performance even at high temperatures.
Due to its excellent physical and chemical properties, quartz glass is widely used in various fields such as electric light sources, semiconductors, optical communication, military industry, metallurgy, building materials, chemistry, machinery, electricity, and environmental protection.