Quartz is obtained from fused silica and mainly consists in pure silica (SiO2 : 99.9%)
- Chemical properties
Quartz is extremely resistant to chemicals :
- Hydrolytic resistance : HGA 1 and HGB 1 Standard
- Acids resistance : S1 Standard
- Alkaline resistance : A1 Standard
Only hydroflouric acid, hot phosphoric acid and hot strong caustic solutions can corrode quartz significantly. Quartz is mostly indicated with alkaline solutions.
- Physical properties
- Thermal expansion coefficient (α=20-300°C) : 5.5 x 10-7 K-1
- Density (20°C) : 2.20 g.cm-3
- Permittivity ε (20°C–1MHz) : 3.7
Its non magnetic properties are also useful to avoid electromagnetic interference.
- Thermal properties
Quartz can resist high temperature and thermal shocks :
- Maximum operating temperature (short lasting) : 1 300 °C
- Strain point : 1 075 °C
- Softening point : 1 730 °C
- Working temperature : 1 700 – 2 100 °C
- Optical properties
Like borosilicate glass, quartz is ideal for use in the visible region of spectrum.
Moreover, unlike borosilicate glass, quartz enables a very high transmission of ultra-violet light. Some qualities of quartz may allow its use in infra-red light.
The use of quartz is therefore prescribed in several cases, among which :
- experiment environment undergoing temperatures over 500 °C
- working in ultra-violet or infra-red light
- exposure to alkaline solutions