L’Fused alumina, also known as electro-fused corundum, is a form of aluminium oxide characterized by a high massive, angular crystal structure, obtained by solidification after a complete melting phase.
In-depth definition : Unlike sintering, the smelting process begins with the melting of bauxite (aluminum ore) or high-purity alumina in a electric arc furnace at extreme temperatures (often in excess of 2000∘C). The molten material is then poured into molds or left to cool slowly in the furnace to form large crystalline masses. After cooling, these masses are crushed, ground and sized to produce grains with sharp, hard edges.
Types, Properties and Industrial Applications
Fused alumina comes in several types, the two main ones being :
- White Fused Alumina (WFA) : Very high purity (≥99%). Properties: very high hardness, friability (grains fracture to create new sharp edges), and white color due to the absence of impurities (iron, titanium).
- Brown Fused Alumina (BFA) : Less pure, but very tenacious, thanks to the presence of small quantities of iron and titanium oxides.
| Field of application | Preferred type | Key role |
|---|---|---|
| High-Performance Abrasives | WFA and BFA | Extreme hardness for cutting, grinding, sanding and surface preparation prior to coating. |
| Refractories | BFA | Stable at very high temperatures and resistant to thermal shock, used for lining furnaces and ladles. |
| Non-slip | BFA | Angular and tenacious grains are incorporated into industrial flooring for safety. |
Fused alumina is the material of choice when you are looking for a maximum hardness for abrasion or a exceptional thermal resistance, properties that are essential to the Industrial Performance in the metalworking, construction and toolmaking sectors.
Key difference: Process and Microstructure
The distinction between the two is critical for the choice of refractory material:
- Sintered alumina : Solid-state process (no melting), producing a microstructure of fine, uniform grain, for the mechanical strength and precision components.
- Fused Alumina : Processes in the liquid state (melting and crystallization), producing angular, rough and extremely hard grains, privileged for abrasive and refractory applications.