Sapphire glass has mechanical and thermal properties similar to technical ceramics.
Sapphire single crystal is characterized by high mechanical, chemical and thermal resistance and also offer a good optical transmission at 200 nm.
Wherever extreme demands on wear resistance, hardness, inertness, thermal and chemical resistance, sapphire is the right solution.
Specific characteristics of sapphire:
- acid-insoluble e.g. to hydrofluoric acid, fluorine or aggressive gases
- excellent optical transmission – from UV to IR
- temperature resistant to 2000 ° C
- Corrosion and abrasion resistance
- extreme hardness, high strength (Mohs hardness 9)
- best compressive strength
- High electrical resistance
- large dielectric constant
Features
Chemical properties
| Crystal structure | hexagonal |
| chemical formula | Al2O3 |
| Purity | 99,997% Al2O3 |
| Density | 3,98g/cm |
Physical properties
| Hardness | Mohs 9 |
| Tensile strength | 0,4 GPa at 25 °C |
| Compressive strength | 2,1 GPa at 25 °C |
| Bending strength | 0,6 GPa at 25 °C |
| Modulus of rupture | 0,9 GPa at 25 °C |
Electrical properties
| Specific resistance | 1011 Ohm/cm at 500°C 106 Ohm/cm at 1000°C 103 Ohm/cm at 2000°C |
| Dielectric strength | 480 kV cm-1 (60 Hz) |
| Dielectric loss index | 0.000030 parallel to C axis (C-plane) 0.000086 perpendicular to C axis (A-plane) |
Thermal conductivity
| Thermal expansion | 6.6 x 10-6 °C-1 (20-50 °C), parallel to C axis 5.0 x 10-6 °C-1 (50°C), perpendicular to C axis |
| Thermal capacity | 0.08 cal cm-1 s-1 °C-1 (25°C) |
| Specific heat | 0.18 cal g-1 °C-1 (25°C) |
Optical properties
| Refractive index: | 1,8 (@ 0,3μ), 1,6 (@5μ) |
| Optical transmission: | to 97%, in the range 0.15 – 6 μm |
Thermal properties
| Application temperature | 2000 °C |
| Melting point | 2053 °C |
Applications
- Protection window / safety glasses
- Fiber e.g. for medical
- Wafer 2″ – 6″ for LEDs
- Lenses for endoscopy
- Protection tubes for thermocouples
- Sight glasses
- Watch glass
- Components in laser technology
- Analytical and plasma technology
- Tubes for high pressure sodium lamps
- Wear resistant components
- Nuclear magnetic resonance spectroscopy / NMR spectroscopy
- IR-/UV-sensors
- Laboratory equipment, laboratory glassware
- Medical instruments
- Implants