sapphire/ruby property

Features:
General
Chemical Formula Al2O3
Crystal System Trigonal
Class Hexagonal-scalenohedral
Melting Temperature 2030oC

Thermal
Thermal Expansion Parallel to C-axis: 6.7?0-6
Perpendicular to C-axis: 5.0?0-6
Specific Heat 0.18 Cal/gmoK?25??

Mechanical
Density 3.98 ~ 4.1g/cm3
Hardness 9Moh’s Scale Hv?1700kg/mm2
Modulus Of Elasticity 340-380Gpa
Compressive Strength 2.1Gpa
Tensile Strength 0.19Gpa

Optical
Index of Refraction Parallel to C-axis:1.769
Perpendicular to C-axis:1.76
Index of IR Transmission 85%

Electrical
Electrical Resistance ?1016?/cm(25°c)
Dielectric Constant 7.5-10

Chemical
Corrosion Resistance: Can not be corroded by acid or alkali at normal temperature, only can be corroded by HF at 300oC