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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:   20/300 = 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:   (20-100°C) 1,38-1,46 W m-1 K-1
Logarithm of the electrical volume resistance in -cm
at    20°C   20
at  100°C   18
at  600°C   12
at 1000°C     8
Dielectrical properties for 1 MHz at 25°C
DZ    3,7
Refractive index nd (=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
Resistance to acid (DIN 12116)  class 1
Resistance to alkali (DIN ISO 695)class 1

Applications

  • 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)