Sapphire Properties

GENERAL

Chemical Formula
 
Al2O3
Crystal Stucture
 
Hexagonal
Unit Cell Dimension
 
a=4.758 Å, c=12.991 Å
PHYSICAL
 
 
Metric
English
Density
 
3.98 g/cm³
0.144 lb/in3
Hardness
 
1525 - 2000 Knoop,  9 mhos
3700° F
Melting Point
 
2310 K (2040° C)
 
STRUCTURAL
Tensile Strength
 
275 MPa to 400 MPa
40,000 to 58,000 psi
 
at 20°
400 MPa
58,000 psi (design min.)
 
at 500° C
275 MPa
40,000 psi (design min.)
 
at 1000° C
355 MPa
52,000 psi (design min.)
Flexural Strength
 
480 MPa to 895 MPa
70,000 to 130,000 psi
Compression Strength
 
2.0 GPa (ultimate)
300,000 psi (ultimate)
MODULUS
Young's Modulus, E
 
345 GPa
50 x 106 psi
(Modulus of Elasticity)
 
 
 
Bulk Modulus, k
 
250 GPa
36 x 106 psi
(Modulus of Compression)
 
 
 
Shear Modulus, G
 
145 GPa
21 x 106 psi
(Modulus of Rigidity)
 
 
 
MOR
 
350 MPa to 690 MPa
50,000 to 100,000 psi
THERMAL
Thermal Conductivity
at 0° C
46.06 W/(m • K)
319.4 BTU in/hr ft2 °F
(60° orientation)
at 100° C
25.12 W/(m • K)
174.2 BTU in/hr ft2 °F
 
at 400° C
12.56 W/(m • K)
87.1 BTU in/hr ft2 °F
Specific Heat at 20° C
 
0.187 cal/(g • °C)
0.1827 BTU/lb °F
Heat Capacity
at 20° C
18.63 cal/ (mole • °C)
18.6 BTU/lb mole °F
 
at 1000° C
29.86 cal/ (mole • °C)
29.9 BTU/lb mole °F
Thermal Expansion Coefficient
20° to 50° C
5.8 x 10-6/ °C
3.2 x 10-6/ °F
(60 degree orientation)
20° to 500°C
7.7 x 10-6/ °C
4.3 x 10-6/ °F
ELECTRICAL
Frequency
 
E perp. to C axis
E ll to C axis
 
 
DielectricConstant
Loss Tangent
Dielectric Constant
Loss Tangent
1 MHz
 
9.39
0.0001
11.58
0.0001
3 GHz
 
9.39
<0.0001
11.58
<0.0001
8.5 GHz
 
9.39
<0.00002
11.58
<0.00002
Volume Resistivity at 25 °C
1014 Ohm • cm