Synthetic ruby and sapphire are monocrystalline aluminium oxides. Sapphire more less is pure ( 99,99% Al 2O3), ruby’s color comes from admixture with a little chromium oxide (CrO 3). Both crystallines are hexagonal rhombohedral structured, hardness of both is ca. 2300 Vickers.
The combination from high E-modul, extreme hardness, brilliant optical characteristics and mechanical and chemical resistance offers phenomenal advantages compared against glass or ceramic!
chemical formula | Al 2O3 |
structure | hexagonal rhombohedral |
molar weight | 101,94 |
mass density, g/cm³ (20 °C) | 3,98 |
Reflexionsverlust, % zwei Oberflächen bei 4 µm | 12 |
dielectric coefficient at 102-108Hz at 298K parallel perpendicular |
|
10,55 | |
8,6 | |
melting pointt, K | 2300 |
heat conductivity, W/(m K) bei 300 K parallel perpendicular |
|
35,1 | |
33.0 | |
thermal expansion, 1/K bei 293 K parallel perpendicular |
|
5,6 x 10 -6 | |
5,0 x 10-6 | |
spec. thermal capacity, cal/(g K) at 298 K | 0,18 |
band gap. eV | 9,9 |
water solubility | Keine |
Mohs hardness | 9 |
Knoop hardness, kg/mm² | 1370 |
elasticity modulus E, GPa | 335 |
shear modulus G, GPa | 148 |
compressive modulus K, GPa at 273 K | 240 |
rupture modulusl, MPa | 350…690 |
Poisson's Ratio | 0,25 |