Quartz glass (also called fused silica) has the simplest chemical composition. It consists practically only of silicon and oxygen (silicon dioxide) and does not contain any admixtures of soda or calcium oxide, in contrast to the commonly used glass tubes / glass rods. The excellent chemical and physical properties make these special glass tubes particularly interesting for applications with high demands. It is worth mentioning that fused quartz tubes are not hygroscopic and have an outstandingly high thermal resistance, permanently withstanding temperatures of up to 1000 °C, and also possess excellent thermal shock resistance. The background to these remarkable thermal properties is the low coefficient of thermal expansion. In addition, quartz glass is characterized by a very low content of impurities. As a result, quartz glass tubing and fused quartz tubes have a high optical quality and are predestined for a wide range of optical applications.
Special properties of quartz glass
Glass tubes and rods made of quartz glass (fused silica) have a number of particularly practical properties:
- high purity of the material
- excellent optical properties
- high temperature resistance up to 1000 °C
- low thermal expansion
- excellent thermal shock resistance
- good transmission in the wavelength range from 190 nm to 3500 nm
- low electrical conductivity
- low dielectric losses
- high resistance to acid, salt solutions and water
- neutral behavior towards many substances
Typical applications
- plant and equipment construction
- components in the semiconductor industry
- material for light guides and optical components
- applications under very high temperatures
- electrical engineering
- sight glasses and flow indicators
- ideal glass for laboratory applications
- excellent in the food industry
- very popular in research and development
Chemical properties
Chemical composition: Silicium dioxide (SiO₂)
Hydrolytic resistance: Water resistance class HGB 1, Acid class S 1, Alkali class A 2
Physical properties
Density: 2.2 g/cm³
Refractive index: ω=1,459
Mohs hardness: 5,5 – 6,5
Compressive strength: 1150 N/mm² at 20 °C
Tensile strength: 50 N/mm² at 20 °C
Young’s modulus of elasticity: 7,25 × 104
Softening temperature: 1710 °C
Electrical properties
Dielectric resistance: 3,70 (106 Hz, 20 °C )
Specific resistance: 1018 Ω × m (at 20 °C)
Breakdown field strength: 250 – 400 KV/cm (20 °C)
