Alumina

Almath Crucibles offer a variety of Alumina products, including  crucibles, tubes and plates. We are also able to produce alumina furnace wear. Our Alumina products have a maximum operating temperature of 1800°C, making them ideal for high temperature applications.

Our high purity alumina (Al2O3 content > 99%) ceramics are purpose built to perform across a wide range of high temperature applications. We use recrystallized alumina in the production of our crucibles as he material offers impressive thermal shock resistance, this is due to the larger grain size (up to 200mm is advantageous).

Our high purity alumina shows considerable resistance to chemical attack due to the lack of glassy phases that tend to determine corrosion resistance.

The electrical and dielectrical properties of the material generally improve with increased purity. Electrical resistance is greatest and dielectrical loss factor is lowest in materials of highest alumina content.

High purity alumina produces a dense and essentially single-phase ceramic on sintering. Grain growth during sintering can be controlled by small additions of MgO up to 0.05%. Our product usually contains a small amount of closed porosity but this can be kept below 0.5% using modern firing techniques.

View the material safety datasheet by clicking the button below.

Material Properties

Please note that the information set forth herein is offered for comparison only, and is not to be construed as absolute engineering data or constituting a warranty or representation for which we assume legal responsibility.

PropertyUnitTestAlumina 99.5%Alumina 99.6%Alumina 99.8%
Densityg.cc-1ASTM C203.83.93.9
Colour****WHITEIVORYIVORY
Elastic ModulusGPaASTM C848350370350
Flexural StrengthMPaASTM F417375379360
Compressive StrengthMPaASTM C773250026002400
Fracture Toughness RangeMpaNOTCHED BEAM4-54-54-5
HardnessGPaROCKWELL 45N828383
Thermal ConductivityW/mKASTM C40827.53030
CTE 25-10010(-6)/0CASTM C3728.28.28.2
Thermal Shockdelta TcNOTE3200200200
Dielectric Strengthac-kv/mm (6.25mm)ASTM D1168.78.78.7
Dielectric Loss250C@1MHzASTM D25200.00020.00010.001
Volume Resistivity1000C ohm-cmASTM D18292×10^62×10^65×10^7
  • DATA MEASUREMENTS – All data measurements are typical and made at room temperature unless otherwise noted.
  • THERMAL SHOCK RESISTANCE – Tests are run by quenching samples into water from various elevated temperatures. The change in temperature where a sharp decrease in flexural strength is observed is listed as ‘delta Tc’.
  • CHEMICAL RESISTANCE – Although all alumina and zirconia ceramics are highly resistant to chemical attack, it is recommended that specific applications are discussed with Almath Crucibles to ensure optimum ceramic selection.

Chemical Composition

Chemical%Value
Al2O3%99.9
MgO%0.05
Na2O%0.05
SiO2%0.04
H2O%0.11
Other%< 0.75

View our full range of Alumina products.

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