Definition and Production
Fused zirconia refractories are manufactured by high-temperature melting of zirconium-rich raw materials, followed by controlled solidification. The resulting product is composed mainly of monoclinic or partially stabilized zirconia (ZrO₂), depending on the process and stabilizers used.
These refractories are characterized by extremely high purity and a dense microstructure, making them ideal for severe-service environments such as glass tanks and metallurgical applications.
Types of Fused Zirconia
There are different forms of fused zirconia used in refractories:
- Monoclinic zirconia: the most common form, offering high resistance to slag and corrosion.
- Partially stabilized zirconia (PSZ): contains additives like MgO or CaO to enhance thermal shock resistance.
- Fully stabilized zirconia (FSZ): used in specific applications requiring ionic conductivity or extreme thermal stability.
Key Properties
Fused zirconia refractories are valued for their superior performance under aggressive operating conditions:
- Exceptional corrosion resistance to molten glass, slags, and chemicals
- High thermal stability exceeding 2400°C
- Low thermal conductivity, making them energy-efficient
- Good mechanical strength at both ambient and elevated temperatures
- Resistance to thermal shock, especially in stabilized grades
Main Applications
Fused zirconia is extensively used in industries where materials must withstand highly corrosive or reactive environments:
- Glass furnaces: critical parts like throat blocks, glass contact zones, and flow channels
- Steel and ferrous metallurgy: nozzles, submerged entry parts, and tundish linings
- Non-ferrous metal production: crucibles, liners, and melting vessels
- Chemical reactors and incineration units
Advantages Over Other Refractory Materials
Compared to standard refractories, fused zirconia offers unique advantages:
- Longer service life due to extreme chemical and wear resistance
- Reduced maintenance costs through durability in hostile environments
- Excellent structural integrity in both oxidizing and reducing conditions
Limitations
Despite their strengths, fused zirconia refractories have a few limitations:
- High production cost due to energy-intensive fusion and raw material quality
- Thermal expansion can be significant if not stabilized properly
- Machinability is limited; often requires precision cutting or pre-shaped designs
Market and Specifications
When selecting fused zirconia products, key parameters include:
- Zirconia content (typically >94%)
- Bulk density and porosity
- Phase composition (monoclinic, tetragonal, cubic)
- Presence of stabilizers like MgO, CaO, or Y₂O₃
These specifications impact performance, thermal behavior, and chemical compatibility with the process environment.
Why Choose Fused Zirconia?
Fused zirconia refractories are the preferred choice for operations where standard alumina or silica-based refractories would fail due to corrosion or erosion. Their reliability under the most aggressive conditions helps improve process stability, safety, and long-term cost-effectiveness.
Conclusion
Fused zirconia offers unmatched resistance to high-temperature corrosion and thermal stress, making it an essential material for critical refractory applications. Whether in glass manufacturing, metallurgy, or high-end chemical processing, these materials ensure consistent performance where other refractories cannot.
