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Alumina ( Al2O3 )

Material Information

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We stock and supply the following standard forms:
Bar Bolt Crucible Fibre Foam Granule Lump Nut Powder
Bar Bolt Crucible Fibre Foam Granule Lump Nut Powder
Rod Sheet Sphere Sputtering Target Tube Washer
Rod Sheet Sphere Sputtering Target Tube Washer

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General Description:  

Minerals containing Alumina represent some 15% of the earth's crust. It is therefore an abundant material and virtually inexhaustable, unlike raw materials for many alloys developed for special applications. The combination of high thermal conductivity, low thermal expansion and high compressive strength leads to good thermal shock resistance, so Alumina is suited to furnace use as crucibles, tubes and thermocouple sheaths. High purity Alumina can be used up to 1700C and is gas tight up to 1300C. Few chemicals attack Alumina. Alumina also shows good electrical insulation at high temperatures, good wear resistance and high hardness, making it suitable for components such as ball valves, piston pumps and deep drawing tools. Diamond tools are needed to machine or grind Alumina. Remarkably, continuous filament yarns have been made from alumina with reasonable but not complete success and two, similar, versions are available from Goodfellow. They are both much less flexible than normal continuous filament yarns and are rather "hairy" i.e. have broken filaments - especially the FP version.

   

Chemical Resistance

Acids - concentrated Good
Acids - dilute Good
Alkalis Good
Halogens Good
Metals Good

Electrical Properties

Dielectric constant 9.0-10.1
Dielectric strength ( kV mm-1 ) 10-35
Volume resistivity @25C ( Ohmcm ) >1014

Mechanical Properties

Compressive strength ( MPa ) 2200-2600
Hardness - Knoop ( kgf mm-2 ) 2100
Hardness - Vickers ( kgf mm-2 ) 1500-1650
Shear strength ( MPa ) 330
Tensile modulus ( GPa ) 300-400

Physical Properties

Apparent porosity ( % ) 0
Density ( g cm-3 ) 3.9
Water absorption - saturation ( % ) 0

Thermal Properties

Coefficient of thermal expansion @20-1000C ( x10-6 K-1 ) 8.0
Melting point ( C ) 2100
Specific heat @25C ( J K-1 kg-1 ) 850-900
Thermal conductivity @20C ( W m-1 K-1 ) 26-35
Upper continuous use temperature ( C ) 1700

Properties for Alumina Fibre

Property Value
Coefficient of thermal expansion - Longitudinal x10-6 K-1 5.7
Density g cm-3 3.9
Modulus GPa 380
Tenacity GPa 1.4

Buy Alumina on-line

We stock and supply the following standard forms:
Bar Bolt Crucible Fibre Foam Granule Lump Nut Powder
Bar Bolt Crucible Fibre Foam Granule Lump Nut Powder
Rod Sheet Sphere Sputtering Target Tube Washer
Rod Sheet Sphere Sputtering Target Tube Washer

Choose a form to search our on-line catalogue  

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