Due to its purity corundum (Aluminium oxide
) is subdivided into
- regular (or brown) aluminium oxide: purity approx. 94 to 98 %.
- semi-friable fused aluminium oxide: purity approx. 98 to 99 %.
- aluminium oxide high purity: purity approx. 99,5 to 100 %.
Through a slight impurity of the corundum its quality is increased. Therefore, semi-friable fused aluminium oxide is mostly used as abrasive. Corundum is wedge shaped and grounds itself round under load.