White fused alumina: high hardness and transparence

White fused alumina is an industrial product. It is melted of high quality aluminium oxide in an electric arc. White fused alumina consists of about 99 % α-aluminium oxide. The outstanding property of white fused alumina is a high hardness and transparency. Only diamonds are tougher. This high hardness is a challenge for every grinding technology. Our micronized white fused alumina flours SEPASIL are characterized by a narrow grain size distribution. Another refining step is the surface-treatment with silanes or silane-based substances which can be adjusted to the respective application.


  • depending on processing: the grain shape is round or splintered

  • high hardness of 9 (Mohs)

  • density of 3.95 g/cm³

  • chemically inert

  • high chemical resistance

  • narrow grain size distribution

  • transparent performance in many binding systems

Key applications:

  • abrasion-resistant wood and decorative coatings

  • laminates

  • casting resin systems and high voltage isolators

High Performance Fillers based on white fused alumina: