Sapphire and Ruby Material Properties
Synthetic Sapphire and Ruby, also known as Corundum, have the same chemical composition, crystal structure and properties of the natural gemstones. Synthetic Sapphire is 99.99% pure Al2O3 and is clear and colorless. Ruby contains a trace of chromium to produce its red color making it easier to see and handle. Defining properties include durability, hardness (measuring 9 on the Mohs scale), non-porosity, corrosion resistance and chemical resistance, has excellent insulating properties and high thermal conductivity. A very pure material, It has good wear resistance and dimensional stability. Having superior optical transmission qualities this material is excellent for use with visible light, infrared and ultraviolet transmission and is regularly used in optical equipment.
Mechanical applications for precision balls include: bearings, valves, pumps, flow meters, metrology instrumentation, medical devices, probes.
Optical applications for precision balls include: lenses, fiber optics, bar code readers, medical devices.
Synthetic Sapphire Verneuil Crystals
| PHYSICAL PROPERTIES | |
|---|---|
| crystalline structure | rhomboerdral hexagonal, single |
| composition | Al2O3 |
| purity | 99.99% |
| main impurities | Na2O, Si, Ca, Fe, Ga, Mg, Ti, Mn, Pb, Cu, Zn, Ni |
| cleavage | conchoidal |
| density | 3.99 – 9.98 |
| dislocation density | 109 – 108 / m2 |
| THERMAL PROPERTIES | |
| melting point | 2320K |
| softening point | 2070K |
| specific heat | 7.5 · 102 j/kg · K at 300K |
| thermal conductivity | 40 W / m · K ⊥ at 300K |
| thermal expansion | 6.2 · 10-6/K ∥ C-axis |
| 5.4 · 10-6/K ∥ C-axis | |
| MECHANICAL PROPERTIES | |
| hardness | Mohs 9 |
| Knoop 2200 face ∥ C-axis | |
| Knoop 1800 face ⊥ C-axis | |
| Young’s modulus | 4.4 · 1011 Pa at 300K |
| modulus of rupture | 4.0 · 108 Pa at 300K |
| compressive strength | 2.1 · 109 Pa at 300K |
| tensile strength | 1.9 · 108 Pa at 300K |
| Poisson’s constant | 0.30 |
| CHEMICAL PROPERTIES | |
| acids and alkalis attack | 0 at 570K |
| porosity | 0 |
| ELECTRICAL PROPERTIES | |
| dielectric constant | 10.6 electric field ∥ C-axis at 300K |
| 8.6 electric field ⊥ C-axis at 300K | |
| electrical resistivity | 109 Ω · m at 770K |
| 104 Ω · m at 1270K | |
| 109 Ω · m at 2270K | |
| OPTICAL PROPERTIES | |
| refractive index Nd at 0.5893 µm | 1.760 face ∥ C-axis |
| 1.769 face ⊥ C-axis | |
| dispersive power (nf – nc) | 0.011 λF = 0.4861 µm λC = 0.6563 µm |
| Transmission, disc thickness 1mm | |
| visible light | excellent |
| infrared | 85% 0.75 – 5 µm |
| 70% 5.5 µm | |
| 50% 6 µm | |
| 80% 0.4 – 0.3 µm | |
| ultraviolet | 60% 0.28 µm |
| 50% 0.20 µm | |
