99%+ Purity Alumina (ASTM D2442 Type IV, IEC 60672 Type C-799)
Type IV alumina is a grade of alumina. The graph bars on the material properties cards below compare type IV 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
2660 MPa 390 x 103 psi
Elastic (Young's, Tensile) Modulus
370 GPa 54 x 106 psi
Flexural Strength
370 MPa 53 x 103 psi
Fracture Toughness
4.5 MPa-m1/2 4.1 x 103 psi-in1/2
Knoop Hardness
1450
Poisson's Ratio
0.22
Shear Modulus
150 GPa 22 x 106 psi
Tensile Strength: Ultimate (UTS)
250 MPa 36 x 103 psi
Electrical Properties
Dielectric Constant (Relative Permittivity) At 1 Hz
9.0
Dielectric Constant (Relative Permittivity) At 1 MHz
9.2
Dielectric Strength (Breakdown Potential)
12 kV/mm 0.46 V/mil
Electrical Dissipation At 1 Hz
0.00031
Electrical Dissipation At 1 MHz
0.00049
Electrical Resistivity Order of Magnitude
14 10x Ω-m
Other Material Properties
Density
4.0 g/cm3 250 lb/ft3
Maximum Temperature: Mechanical
1730 °C 3140 °F
Maximum Thermal Shock
200 °C 380 °F
Melting Onset (Solidus)
2040 °C 3700 °F
Specific Heat Capacity
880 J/kg-K 0.21 BTU/lb-°F
Thermal Conductivity
30 W/m-K 17 BTU/h-ft-°F
Thermal Expansion
7.3 µm/m-K
Common Calculations
Stiffness to Weight: Axial
52 points
Stiffness to Weight: Bending
61 points
Strength to Weight: Axial
18 points
Strength to Weight: Bending
22 points
Thermal Diffusivity
8.6 mm2/s
Thermal Shock Resistance
6.6 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