Background

Alumina, Al2O3, is available from Ceramaret with a purity of up to 99.9%. It is a polycrystalline material with a grain size of 1 to 5 microns, an average density of 3.95 g/cm³ and a hardness of about 2000 Vickers.

AZoM - Alumina from Ceramaret
Physical Properties

Property


Value

Atomic composition


>99%

Crystalline structure


Corundum

Grain size (microns)


1-5

Density (g/cm3)


3.95

Water absorption (%)


0
Mechanical Properties at 20°C

Property


Value

Vickers hardness (Hv 500g)


1800-2000

Tensile strength (N/mm2)


200-250

Bending strength (N/mm2)


200-600

Compressive strength (N/mm2)


1900-2000

Young’s modulus (N/mm2)


3.8x105

Poisson’s ratio


0.25-0.30

Fracture toughness KIC -½ (MPa.m)


4-5
Thermal Properties

Property


Value

Dilation co-efficient (20-2000°C) (°C-1)


8.4x10-6

Specific heat 100°C (J/kg.K)


930

Thermal conductivity at 20°C (W/m.K)


40

Thermal shock resistance (°C)


200
Electrical Properties

Property


Value

Resistivity at 20°C (ohm.cm)


>1014

Dielectric constant at 20°C and 1GHz


9.5

Dielectric rigidity at 50Hz (KV/mm)


30
Chemical Properties

Chemicals


Concentration


Temperature


Time


Rating

HCl


35%


Boiling


30 min


A

HNO3


70%


Boiling


30 min


A

H2SO4


98%


Boiling


30 min


A

H3PO4


90%


Boiling


30 min


B

HF


60%


20


24 hr


C

KOH solution


10%


80


7 day


A

KOH boiling





500


24 hr


C

NaOH boiling





500


24 hr


B

Na2CO3 boiling





900


24 hr


B

Na2SO4 boiling





1000


24 hr


A

KF boiling





90


4 hr


D