Introduction to Quartz Glass

　　Quartz glass is an amorphous material composed of a single component, SiO2, containing trace metallic impurities and varying levels of hydroxyl groups (OH); it is classified as a specialty glass. Internationally, it is commonly referred to as quartz or fused silica. According to the building materials industry standard (JC/T 185-2013), it is divided into three categories based on its transmission characteristics: ultraviolet quartz glass (ZS), visible‑light quartz glass (KS), and infrared quartz glass (HS).

　　Due to its microscopic structure of silicon–oxygen tetrahedra [SiO4], quartz glass exhibits physicochemical properties unmatched by other glasses, earning it the title “king of glasses.” Consequently, it is widely employed in fields such as nuclear technology, aerospace, precision optics, and the semiconductor industry.

　　The unique structure and manufacturing process of quartz glass endow it with outstanding properties in terms of purity, chemical and thermal stability, and optical performance.

　　 1. Purity

　　Purity is a critical parameter for quartz glass, significantly influencing its physicochemical properties and application scope, including devitrification tendency, high‑temperature strength, softening point, optical transmittance, thermal stability, chemical resistance, radiation resistance, and fluorescence characteristics. Quartz glass used in the semiconductor industry demands exceptionally high purity; even trace impurities can severely compromise the electrical performance, service life, and integration density of semiconductor materials. Synthetic quartz can achieve a purity exceeding 99.9999%.

　　 2. Chemical Stability

　　With the exception of hydrofluoric acid and hot phosphoric acid, quartz glass exhibits inertness toward all other acids, making it an excellent acid-resistant material. At room temperature, alkalis and salts also cause only slight corrosion to quartz glass; therefore, quartz glass can be used when in contact with these reagents as well.

　　 3. Thermal Stability

　　Quartz glass exhibits an extremely low coefficient of thermal expansion, approximately 5.5 × 10⁻⁷ /°C—about one-twentieth that of ordinary glass—and also boasts excellent resistance to thermal shock. Moreover, quartz glass possesses high temperature resistance, allowing for prolonged use at 1200°C. Quartz glass subjected to doping treatment can achieve ultra‑low or even zero thermal expansion.

　　 4. Optical Performance

　　Quartz glass exhibits unique optical properties, with high transmittance across the spectral range from the deep ultraviolet to the near infrared (185–3500 nm).

　　In summary, quartz glass exhibits outstanding properties, including high-temperature resistance, a low coefficient of thermal expansion, excellent chemical stability, superior electrical insulation, low and stable ultrasonic delay, and broad‑band optical transmission. Moreover, its characteristics—such as bubble content, streaks, homogeneity, stress‑induced birefringence, and mechanical performance—are unmatched by other optical glasses. Quartz glass is one of the indispensable advanced materials in cutting‑edge technologies—including space technology, nuclear technology, and defense equipment—as well as in industries like semiconductors, optical communications, and electric lighting.