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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


Poisson's Ratio


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


Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

12 kV/mm 0.46 V/mil

Electrical Dissipation At 1 Hz


Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

14 10x Ω-m

Other Material Properties


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