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Sapphire Material Properties
Synthetic sapphire properties make it the material of choice for a variety of applications ranging from optical sapphire windows for military sensor systems to tubes, pins, rods, and lenses for industrial and semiconductor markets. Sapphire's unique properties make it a cost-effective solution where high performance and long life are critical, including extreme conditions such as high-temperature, high-pressure or harsh chemical and physical environments.
One of the hardest materials in existence, sapphire is virtually scratch-proof which helps it maintain its integrity in demanding physical environments. It has a melting point of over 2000 °C, making it ideal for high-temperature applications. It is chemically inert and easily withstands harsh chemicals such as fluorine plasma and other industrial gasses and fluids, with no particle generation. In addition, sapphire can transmit ultraviolet, visible and infrared light as well as microwaves, a range broader than most materials.
Uses/Applications
- Transparent armor
- Opto-mechanical windows
- Semiconductor manufacturing
- Intraoperative imaging, including skull pins
- Industrial
Features/Benefits
- Single (Al2O3) crystal, highest purity possible, no grain boundaries
- Minimal to no particle contamination
- High melting point, 2053oC
- Hardness next to diamond on Mohs Scale of Hardness: extremely scratch-resistant
- Chemically inert (non-reactive in most process environments)
- Superior rigidity (435 Gpa, 6x stiffer than quartz)
- Transparent - transmits UV - visible - IR wavelengths
- Radiotranslucent
- Can be made in complex shapes
Physical/Mechanical
| Properties | Value |
|---|---|
| Density | 3.97 gm/cm3 (0.143 lb/in3) (25°C) |
| Young’s Modulus | 435 GPa (63 x 106 psi) parallel to C-axis (25°C) 386 GPa (56 x 106 psi) parallel to C-axis (1000°C) |
| Modulus of Rigidity (Shear Modulus) | 175 GPa (26 x 106 psi) |
| Flexural Strength | 1035 MPa (150 kpsi) parallel to C-axis (25°) 760 MPa (110 kpsi) perpendicular to C-axis (25°) |
| Compressive Strength | ≈2 GPa (300 kpsi) (25°) |
| Hardness |
9 on Mohs scale (between 20° and 25°C) 1900 Knoop parallel to C-axis |
Optical
| Properties | Value |
|---|---|
| Transmission | UV through midwave IR (~200-5000nm) |
| Uniaxial Negative Refractive Index | Ordinary ray (C-axis) No = 1.768 Extraordinary ray Ne-1.760 Birefringence: 0.008 |
| Temperature Coefficient of Refractive Index | 13 X 10-6/°C (visible range) |
| Spectral Emittance | 0.1 (1600°C) |
| Spectral Absorption | 0.1 – 0.2cm-1 (0.66 μm, 1600°C) |
Thermal
| Properties | Value |
|---|---|
| Melting Point | 2053°C (3727°F) |
| Specific Heat | 0.181 cal/gm°K (25°C) 0.300 cal/gm°K (1000°C) |
| Thermal Conductivity | 0.4 watts/cm°K (25°C) 0.1 watts/cm°K (1000°C) |
| Thermal Expansion Coefficient | (25 – 1000°C) 8.8 x 10-6; parallel to C-axis 7.9 x 10-6; perpendicular to C-axis |
Material Comparison to Saint-Gobain Synthetic Sapphire |
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|---|---|---|---|---|---|---|---|---|
|
Type |
Material |
Density g/cc |
Areal Density psf/in |
Young's Modulus Gpa |
Knoop Hardness Kg/mm2 |
Fracture Toughness MPa-m1/2 |
Thermal Conductivity W/m-K |
Thermal Expansion 10-7/K |
| Ceramic | Sapphire | 3.9 | 20.2 | 435 | 2000 | 2 | 32 | 60 |
| ALON® | 3.69 | 19.2 | 323 | 1850 | 2 | 9.6 | 56 | |
| Spinel | 3.58 | 18.6 | 277 | 1645 | 1.5 - 2 | 14.7 | 60 | |
| Glass | Soda-Lime Glass | 2.52 | 13.1 | 69.6 | 585 | 0.75 | 0.9 - 1.3 | 90 |
| Glass-Ceramic | Li-Alumino-Silicate | 2.52 | 13.1 | 88.5 | 570 | 1.1 | 1.6 - 1.3 | 0 |
Standard available sheet product features include:
- Unpolished, “As Grown”, thickness from .060” to .500” (1.5 to 12.7 mm)
- Polished thickness from .030” to .35” (0.76 to 8.9 mm)
- Widths to 12.0” (304 mm), Lengths to 81.0” (2057 mm)
- Disk diameters 0.125” to 12.0” (3.1 to 304 mm)
Standard available tube sizes range from .06” to 1.7” (1.5 mm to 43.0 mm) outside diameter
Standard available rod sizes up to .30” (7.6 mm) diameter and 40.0” (1016 mm) length