SAPPHIRE PROPERTY

General

Chemical Formula

Al2O3

Crystal System

Trigonal

Class

Hexagonal-scalenohedral

Thermal

Melting Temperature

2030oC

Thermal Expansion

Parallel to C-axis: 6.7×10-6

Perpendicular to C-axis: 5.0×10-6

Specific Heat

0.18 Cal/gmoK(25oC)

Mechanical

Density

3.98-4.1g/cm3

Hardness

9 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

83%

Electrical


Electrical Resistance

1011Ω/cm

106Ω/cm

103Ω/cm

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