Menu (ESC)

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


Poisson's Ratio


Tensile Strength: Ultimate (UTS)

250 MPa 36 x 103 psi

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 Hz


Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

11 kV/mm 0.42 V/mil

Electrical Dissipation At 1 Hz


Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

12 10x Ω-m

Other Material Properties


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