Silica, Vitreous Silica

Abstract

Vitreous silica is a high temperature, single‐component glass commercially available in a wide range of purities. It has superior chemical resistance, low thermal expansion, and excellent optical transmission from the uv to the near‐ir. Thermal history and trace contamination can have significant effects on a number of properties, ranging from electrical conductivity to absorption characteristics. Vitreous silica is the material of choice for a variety of commercial and scientific applications, including tubing and containers for chemical processing, uv‐optical elements, envelope material of mercury vapor lamps, and windows for space vehicles. Vitreous silica's high viscosity, even at its melting point, precludes the use of traditional glass‐forming techniques. Manufacture usually involves specialized methods, such as flame hydrolysis or high temperature sintering in helium or vacuum.