Quartz glass
Characteristics of quartz glass
Quartz glass is a one-component glass (SiO2). It is one of the most valuable materials for both science and industry. There is a distinction between synthetic and natural quartz glass. Synthetic quartz glass is made from pure silicon tetrachloride (SiCl4) following the Flammpyrolyse-method. The raw material of quartz glass is a natural crystal mined from the earth as rock crystal or pegmatite quartz. The raw material is pulverized to a fine-particle granulate and melted to quartz glass in an oxy-hydrogen flame.
Quartz glass features
- good transmission behavior in ultra-violet, visible and infrared wavelengths
- high temperature endurance
- a low coefficient of thermal expansion
- good thermal shock resistance
- excellent electrical insulation
- high chemical purity
- a maximum operating temperature of 1100°C (permanently), or 1300°C (short-time)
Thermal extension: a20/300 = 5,1×10-7 K-1
Density: 2,2 g/cm3
Modulus of elasticity: 70000 N/mm2
Poisson's ratio m: 0,17
Compressive strength: 1150 N/mm2
Tensile strength: 50 N/mm2
Bending strength: 67 N/mm2
Thermal conductivity lw (20-100°C) 1,38-1,46 W m-1 K-1
Logarithm of the electrical volume resistance in V/cm
at 20°C 20
100°C 18
600°C 12
1000°C 8
Dielectrical properties for 1 MHz at 25°C
DZ 3,7
Refractive index nd (l=587,6 nm) 1,459
Stress-optical constant 3,57×10-6 N -1
Chemical resistance
Resistance to water (DIN ISO 719): HGB 1 Hydrolytic class 1
Säurebeständigkeit nach (DIN 12116): class 1
Laugenbeständigkeit (DIN ISO 695): class 1
Use
- high-temperature processes (high temperature resistance)
- semiconductor- and light-industry (purity)
- optics (good light transmission in visible, UV and IF wavelengths)
- laser technology
- electronics and electro-technology (low conductivity, high penetration field strength, low dielectric loss factor)
- chemistry and pharmaceutics (chemical resistance, not hygroscopic, chemical purity, thermal shock resistance)