Silikaglas

Silikaglas, also known as fused silica or fused quartz in many languages, is an amorphous, non-crystalline form of silicon dioxide with exceptionally high purity. It is produced by melting high-purity quartz sand or cristobalite and rapidly forming it into glass. The material is distinguished from common soda-lime glasses by its very low impurity content, which gives it unique optical and thermal properties.

Key properties include excellent transparency over a wide wavelength range, from the ultraviolet around 180 nanometers to the near-infrared, and very low coefficient of thermal expansion, typically about 0.5 × 10^-6 per kelvin. It can withstand high temperatures, with a melting point around 1700 degrees Celsius, and exhibits strong resistance to many chemicals. However, it is susceptible to attack by hydrofluoric acid and to stress-related crazing under certain conditions. The material is also highly brittle and hard, making precision machining and polishing important for optical use. The presence of hydroxyl (OH) groups can reduce UV transmission, so ultra-pure grades are often specified for UV applications.

Production methods center on melting silica at high temperatures and forming the melt into desired shapes, such as blocks, windows, tubes, and fibers. Variants include extremely pure fused silica for optical components and fused quartz for high-purity laboratory and semiconductor uses. In addition to optics, silikaglas is used in crucibles, photolithography equipment, and specialized laboratoryware due to its chemical inertness and thermal stability.

Safety considerations include the inhalation hazard of fine silica dust, which can cause respiratory issues with chronic exposure. Proper handling and containment are essential in processing environments.