PROPERTIES of Sapphire (Al2O3)

MECHANICAL PROPERTIES
Young Modulus : 345 GPa
Shear Modulus : 145 GPa
Bulk Modulus : 240 GPa
Knoop Hardness : 22 GPa
Mohs Hardness : 9
Vickers Hardness : 1570...1750
Modulus of Rupture : 420 MPa at 20°C
: 280 Mpa at 500°C
Apparent Elastic Limit : 275 MPa
Poisson constant : 0.30
Density : 3.98 g/cm3 at 20°C

THERMAL PROPERTIES
Melting Point : 2030°C
Specific Heat : 105 J/kg.°C at – 182.15°C
: 761 J/kg.°C at 17.85°C
Coefficient of thermal expansion : 6.66 x 10-6 K-1 // c axis at 50°C
: 5 x 10-6 K-1 ┴ c axis at 50°C
Thermal conductivity : 10000 (W/m·°C) at -243°C
: 40 (W/m·°C ) at 27°C
: 4 (W/m·°C ) at 1227°C

ELECTRICAL PROPERTIES
Resisitiviy : 1016 Ω-cm at 27°C
: 1011 Ω-cm at 300°C
Dielectric resistance at 60Hz : 48x106 V/m
Dielectric Strength : 17kV/mm
Dielectric Costant : 10.6 // c axis at 27°C ; 106Hz
: 8.6 ┴ c axis at 27°C ; 106Hz
Loss coefficient : < 103 at 27°C

OPTICAL PROPERTIES

Refractive Index : n0 = 1.7717; ne = 1.76355 at 50.532μm
Puissance dispersivity (nf-nc) : 0.011; λf = 0.4861μm; λc = 0.6563μm
Emissivity : < 0.02 @ 880°C; λ = 2.6 at 3.7μm
dn/dt : 13 x 10-6K-1