Fused zirconia corundum bricks-commonly known as AZS brick-is the most critical refractory material used in the glass industry today. Its exceptional resistance to molten glass corrosion makes it indispensable for glass melting tanks, working ends, throat blocks, doghouse crowns, and feed channels. However, choosing the right fused zirconia corundum brick grade and supplier is a highly technical decision that directly impacts furnace lifetime, production efficiency, and glass quality.
This article explains why AZS bricks have become the industry standard, how they are produced, where they perform best, and what global buyers should look for when sourcing AZS bricks for high-temperature furnaces.
1. What Exactly Is a Fused AZS Brick?
Fused zirconia corundum brick is made by electro-fusing alumina and zirconia in an arc furnace at temperatures above 1900°C, followed by casting, annealing, and precise machining. The brick's microstructure consists mainly of:Dense corundum (Al₂O₃) crystals,Zirconia-enriched glassy phase,interlocking crystal network
The result is a refractory with extremely low porosity, high chemical stability, and outstanding resistance to molten glass erosion.
2. Why Glass Furnaces Rely on Fused Zirconia Corundum Bricks
Molten glass is extremely aggressive, especially in contact with refractories for long periods. AZS bricks are uniquely suited for these conditions for several reasons.
(1) Exceptional Corrosion Resistance
The dense microstructure prevents molten glass from penetrating the brick. AZS 41# shows:Minimal reaction with alkalis,High resistance to erosion from molten glass streams,Lower bubble generation risk
These bricks maintain stability even after months of continuous high-temperature operation.
(2) Low Glass Pollution and Stable Melting Quality
One major challenge for glass producers is avoiding refractory pollution. AZS bricks provide: Low exudation,Minimal blister formation, No "stone defect",Stable glass color and clarity
This is critical for producing high-value products such as solar glass, LCD glass, pharmaceutical bottles, and high-end tableware.
(3) High Thermal Shock Resistance
Although glass furnaces typically operate continuously, they still experience temperature gradients. AZS bricks:Maintain structural integrity,Resist cracking during thermal cycling,Reduce early furnace wear
This contributes directly to longer furnace service life.
(4) Strong Mechanical Strength
The fused structure gives AZS bricks:High load-bearing capability
,Resistance to creep and deformation,High flexural strength
These properties are particularly important in throat blocks and sidewall areas where mechanical stress is severe.
3. Where Fused Zirconia Corundum Bricks Are Used
Glass furnaces contain multiple zones, each with different refractory requirements. AZS bricks are strategically placed in high-aggression areas, including:
Key Furnace Positions
Throat blocks,Electrode blocks,Working-end sidewalls,Doghouse walls,Glass contact blocks,Riser walls and flow zones,Channel blocks,Superstructure sections exposed to alkali vapors
These areas suffer the highest corrosion rates. Using the correct AZS grade reduces failure risk and improves furnace efficiency.
4. AZS Brick Defects and How Quality Suppliers Avoid Them
Poor-quality fused zirconia corundum bricks can cause serious production issues. Common defects include:Exudation ("weeping") of glassy phase,Bubbles or blisters in molten glass,Cracking during thermal cycling,Poor corrosion resistance,Unstable ZrO₂ distribution
A reliable manufacturer minimizes these problems through:
High-purity raw materials
Fully sealed electric arc fusion furnaces
Strict casting temperature control
Slow, uniform annealing
CNC machining for dimensional accuracy
This ensures AZS bricks perform consistently under severe furnace conditions.
5. How to Choose the Right AZS Grade?
The choice depends on your furnace design, melting capacity, and operating conditions:
AZS 33#:Best for non-critical corrosion zones,Economical option,Suitable for wine bottles, lighting glass, float glass
AZS 36#:Stronger corrosion resistance,Used for sidewalls, furnace corners,Ideal for soda-lime and daily-use glass
AZS 41#:Highest corrosion resistance,Best for throat, doghouse, and melter bottoms,Essential for electronic glass, borosilicate, and high-transparency glass
If your furnace has rapid wear in hot-contact areas, AZS 41# is the recommended choice despite the higher cost.
Fused zirconia corundum bricks are not just another refractory-they are the critical structural foundation that determines furnace efficiency, corrosion resistance, and glass quality. Their unmatched performance in high-temperature glass contact zones makes them irreplaceable.
For glass producers aiming to reduce maintenance downtime and extend furnace life, selecting high-quality AZS bricks-and working with a technically competent supplier-should be a top priority.
