82-86% Purity Alumina (ASTM D2442 Type I, IEC 60672 Type C-780)
Type I alumina is a grade of alumina. The graph bars on the material properties cards below compare type I alumina to other oxide-based engineering ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Compressive (Crushing) Strength
1920 MPa 280 x 103 psi
Elastic (Young's, Tensile) Modulus
220 GPa 32 x 106 psi
Flexural Strength
260 MPa 38 x 103 psi
Fracture Toughness
3.7 MPa-m1/2 3.3 x 103 psi-in1/2
Knoop Hardness
960
Poisson's Ratio
0.22
Tensile Strength: Ultimate (UTS)
250 MPa 36 x 103 psi
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
8.0
Dielectric Constant (Relative Permittivity) At 1 MHz
7.8
Dielectric Strength (Breakdown Potential)
11 kV/mm 0.42 V/mil
Electrical Dissipation At 1 Hz
0.0011
Electrical Dissipation At 1 MHz
0.0013
Electrical Resistivity Order of Magnitude
12 10x Ω-m
Other Material Properties
Density
3.4 g/cm3 210 lb/ft3
Maximum Temperature: Mechanical
1310 °C 2390 °F
Maximum Thermal Shock
250 °C 490 °F
Melting Onset (Solidus)
2040 °C 3700 °F
Specific Heat Capacity
940 J/kg-K 0.22 BTU/lb-°F
Thermal Conductivity
14 W/m-K 8.2 BTU/h-ft-°F
Thermal Expansion
6.7 µm/m-K
Common Calculations
Stiffness to Weight: Axial
35 points
Stiffness to Weight: Bending
58 points
Strength to Weight: Axial
20 points
Strength to Weight: Bending
25 points
Thermal Diffusivity
4.4 mm2/s
Thermal Shock Resistance
12 points
Followup Questions
Further Reading
ASTM D2442: Standard Specification for Alumina Ceramics for Electrical and Electronic Applications
Ceramic and Glass Materials: Structure, Properties and Processing, James F. Shackelford and Robert H. Doremus (editors), 2008
Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012
IEC 60672-3: Ceramic and glass-insulating materials - Part 3: Specifications for individual materials
Springer Handbook of Condensed Matter and Materials Data, W. Martienssen and H. Warlimont (editors), 2005