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Fused Cast AZS Block – Professional Technical Article
1. Overview
Fused cast AZS (Alumina-Zirconia-Silica) blocks are high-performance electrofused refractory materials exclusively designed for glass melting furnaces. Manufactured by electric arc melting at ultra-high temperature and controlled annealing, AZS blocks feature dense cast structure, low permeability, and stable chemical resistance against molten glass. They are the standard lining material for long-campaign glass furnace hot zones.
2. Material Classification & Chemical Basis
AZS grades are strictly defined by ZrO₂ content, which determines corrosion resistance and application scenarios:
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AZS 33#: ZrO₂ ≈ 33%. General grade for medium-load furnace sidewalls with moderate temperature and glass flow rate.
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AZS 36#: ZrO₂ ≈ 36%. Balanced mechanical and chemical performance, widely used for most commercial glass furnace linings.
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AZS 41#: ZrO₂ ≈ 41%. High-zirconium premium grade for severe erosion zones with high temperature and fast glass convection.
The crystalline phase consists of corundum and baddeleyite uniformly distributed in a stable silicate glass matrix. Higher ZrO₂ proportion effectively reduces glass melt erosion rate and improves structural stability under continuous high temperature.
3. Core Technical Properties
3.1 Molten Glass Corrosion Resistance
The dense pore-free cast structure prevents capillary penetration of molten glass. The composite crystal system maintains structural inertia against alkaline glass melt, effectively slowing down lining recession during long-term furnace operation. This is the primary factor extending furnace campaign life.
3.2 Controlled Glass Phase Performance
Residual glass phase content and exudation temperature are strictly controlled. Low glass phase precipitation at working temperature minimizes glass defects such as stones, striae and bubbles, avoiding refractory contamination to molten glass.
3.3 Low Porosity & High Bulk Density
Precise melting and annealing eliminate internal shrinkage cavities and open pores. Low apparent porosity and high bulk density ensure structural integrity, anti-permeability and mechanical strength under sustained high-temperature load.
3.4 Thermal Stability & Thermal Shock Resistance
AZS blocks deliver stable linear thermal expansion and excellent thermal shock resistance. Reasonable expansion coordination avoids crack propagation and block dislocation during furnace heating, cooling and periodic temperature fluctuation.
4. Production & Quality Control
All AZS blocks are produced via electric arc fusion, integral casting, staged annealing and precision CNC finishing. Strict quality inspection covers chemical composition, bulk density, apparent porosity, glass phase exudation rate, thermal expansion coefficient and corrosion resistance. Full test reports and certificates are provided for each batch.
5. Typical Application Zones
Suitable for all critical hot zones of soda-lime glass, borosilicate glass and special glass melting furnaces:
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Glass melting tank sidewall
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Furnace throat and flow channel
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Bubbler block and superstructure hot areas
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Charging doghouse and furnace bottom hot spots
6. Technical Support & Customization
We provide grade selection optimization, custom-shaped casting, on-site precision machining and refractory lining technical solutions for new furnace construction and cold repair projects. All customized blocks comply with furnace assembly tolerance standards to ensure seamless installation and long-term stable operation.
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