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93-95% Purity Alumina (ASTM D2442 Type II, IEC 60672 Type C-786)

Type II alumina is a grade of alumina. It has the lowest strength compared to the other variants of alumina. The graph bars on the material properties cards below compare type II 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

2260 MPa 330 x 103 psi

Elastic (Young's, Tensile) Modulus

270 GPa 40 x 106 psi

Flexural Strength

320 MPa 46 x 103 psi

Fracture Toughness

3.9 MPa-m1/2 3.6 x 103 psi-in1/2

Knoop Hardness


Poisson's Ratio


Shear Modulus

120 GPa 18 x 106 psi

Tensile Strength: Ultimate (UTS)

210 MPa 30 x 103 psi

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 Hz


Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

12 kV/mm 0.48 V/mil

Electrical Dissipation At 1 Hz


Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

13 10x Ω-m

Other Material Properties


3.7 g/cm3 230 lb/ft3

Maximum Temperature: Mechanical

1550 °C 2820 °F

Maximum Thermal Shock

250 °C 480 °F

Melting Onset (Solidus)

2040 °C 3700 °F

Specific Heat Capacity

900 J/kg-K 0.22 BTU/lb-°F

Thermal Conductivity

19 W/m-K 11 BTU/h-ft-°F

Thermal Expansion

7.2 µm/m-K

Common Calculations

Stiffness to Weight: Axial

41 points

Stiffness to Weight: Bending

59 points

Strength to Weight: Axial

16 points

Strength to Weight: Bending

21 points

Thermal Diffusivity

5.8 mm2/s

Thermal Shock Resistance

7.7 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