Alumina

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

High purity alumina (Al2O3 content > 99%) ceramics are ideal for high temperature applications. Re-crystallised alumina is used in crucibles as it offers the best thermal shock resistance due to the larger grain size (up to 200m m is advantageous).

Such 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 generally improve with increasing 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%. The product usually contains a small amount of closed porosity but this can be kept below 0.5% using modern firing techniques.