is a high-purity corundum material produced by electric melting of premium bauxite under a controlled reducing atmosphere. It serves as a cost-effective alternative to white fused alumina in refractory and abrasive industries.  

Definition & Nomenclature  

- Named for its grayish appearance between brown fused alumina (dark) and white fused alumina (pure white).  

- Mineralogical name: *Bauxite-based dense fused corundum*.  

Production Process

Raw Materials: High-grade bauxite mixed with carbon (reductant), iron scraps (settling agent), and iron scale (decarburizer).  

Key Stages： 

Reduction phase: Excess carbon removes TiO₂;  

Decarburization phase: Oxygen blowing eliminates residual carbon.  

Efficiency: 30% lower cost and 67% less energy consumption vs. industrial alumina melting.  

Performance Advantages  

Dual Properties: High hardness of white alumina + toughness of brown alumina.  

Economic Value: Replaces 25%-50% of dense or white corundum in refractories, reducing costs.  

Primary Applications  

Refractories: Slide gates, castables for iron troughs, wear-resistant bricks.  

Precision Casting: Abrasive media and ceramic reinforcement.  

Limitations: Carbon content must be ≤0.14% to prevent explosive spalling; iron impurities controlled to avoid surface blackening.