Hollow alumina spheres for high-temperature kiln refractory materials
Hollow alumina spheres are premium lightweight aggregates specifically designed for high-temperature kiln refractory applications. Produced from industrial alumina through an electric fusion and blowing process, these spheres feature dense spherical shells, uniform particle size distribution, and exceptional thermal and mechanical properties. They are widely used in working linings and backup layers of various high-temperature furnaces, including petrochemical crackers, gasifiers, steel reheating furnaces, and ceramic kilns.
Key Advantages
Superior High-Temperature Resistance
Composed primarily of α-Al₂O₃ phase, hollow alumina spheres offer a refractoriness exceeding 1800°C. They maintain structural integrity under both oxidizing and reducing atmospheres without melting or deforming, making them suitable for direct exposure to flames and hot gases in the hottest zones of industrial kilns.Excellent Thermal Insulation
The unique hollow internal structure creates a highly porous aggregate with a closed-cell configuration. This results in an extremely low thermal conductivity of 0.3–0.8 W/(m·K) at 800°C. When incorporated into lightweight refractory bricks or castables, it significantly reduces heat loss through furnace walls, leading to 10–20% energy savings in fuel consumption.Lightweight and Energy-Efficient
With a bulk density of 0.6–0.9 g/cm³, hollow alumina spheres enable the production of refractory bricks with a bulk density of only 1.2–1.6 g/cm³. This represents a 40–50% weight reduction compared to conventional dense refractory bricks. Lighter furnace linings reduce the load on steel structures, lower transportation costs, and simplify installation.High Purity and Chemical Stability
Featuring Al₂O₃ content of ≥99% and minimal impurities (Fe₂O₃ ≤0.15%, SiO₂ ≤0.2%), hollow alumina spheres exhibit excellent resistance to acidic and alkaline slags as well as molten metals. They do not contaminate kiln charges or react with process materials, ensuring product purity in demanding applications such as high-temperature gasifiers and specialty glass furnaces.
Typical Applications
Hollow Alumina Sphere Bricks – Used as working linings or backup linings in kilns operating up to 1750°C continuously (1800°C for short periods).
Lightweight Castables and Plastics – Mixed with high-alumina cement or other binders for cast-in-place linings, offering ease of installation and repair.
Prefabricated Shapes – Manufactured into burner blocks, kiln doors, arch crowns, and other complex profiles.
Technical Specifications (Typical)
| Property | Typical Value |
|---|---|
| Al₂O₃ content | ≥99% |
| Refractoriness | ≥1800°C |
| Bulk density | 0.6–0.9 g/cm³ |
| Particle size range | 0.2–5.0 mm (customizable) |
| Thermal conductivity (800°C) | 0.3–0.8 W/(m·K) |
| Maximum service temperature | 1750°C (long term), 1800°C (short term) |
Conclusion
By selecting hollow alumina spheres as the aggregate for high-temperature kiln refractories, you achieve an optimal balance of lightweight construction, superior thermal insulation, and exceptional heat resistance. This translates directly into lower energy costs, extended campaign life, and reduced structural load. Please contact us for samples, technical data sheets, or customized solutions for your specific kiln requirements.
