The Complete Guide to Selecting AZS Electrofused Bricks and Evaluating Suppliers: From Grade and Quality Control to Kiln Lifespan

Electrofused AZS bricks (fused zirconia-alumina bricks, also known in the industry as electrofused bricks) are the core refractory materials that come into direct contact with high-temperature molten glass in glass melting furnaces. Whether for float glass, container glass, or photovoltaic rolled glass, the service life of critical components such as tank walls, flow channels, and furnace hearths depends largely on the correct selection of electrofused bricks and the supplier’s ability to deliver high-quality products.

This article addresses seven key questions that frequently arise during actual product selection and supplier evaluation, from the perspective of glass manufacturers’ procurement and technical decision-making.

I. How to Choose Between AZS-33, 36, and 41? A Zone Comparison Chart

Many users search for “AZS brick selection guide” or “AZS 33 vs 36 vs 41,” essentially seeking a clear zoning plan. Fused brick grades are classified by ZrO₂ content, but selection should not be based solely on chemical composition; rather, it should be tied to the specific furnace location and glass type:

AZS-33 (approx. 32–34% ZrO₂): Suitable for upper structures—the arch, breast wall, small furnace opening, and upper part of the regenerator. Moderate corrosion resistance is required, with a focus on cost-effectiveness.

AZS-36 (ZrO₂ approx. 35–37%): Main tank walls, furnace benches, and charging port corners. Balances erosion resistance and thermal shock resistance; this is the most widely used grade in bottle and float glass furnaces.

AZS-41 (ZrO₂ approx. 40–42%): Side walls of the melt channel, liquid level line, electrode hole bricks, bubbling bricks, and borosilicate glass melting sections. Offers the highest level of corrosion resistance and is used in critical areas that determine furnace lifespan.

The selection framework can be summarized by three questions: What type of glass is being produced? What is the operating temperature? What is the target kiln lifespan? The intersection of the answers to these three questions determines the recommended grade and zoning plan.

II. What are the key quality indicators for fused bricks?

Chemical composition is merely the entry ticket. The true differences in quality stem from the following five factors:

Bulk Density: Typically required to be ≥3.85 g/cm³ (Grade 36) or ≥3.95 g/cm³ (Grade 41). Higher density indicates lower porosity and greater resistance to erosion.

Glass Phase Content and Leaching Temperature: Excessive leaching contaminates the glass melt, while insufficient leaching results in inadequate thermal shock resistance. High-quality products should have a stable leaching temperature range.

Oxidation Level (Fe²⁺/Total Iron Ratio): The lower the better. This reflects the control of the oxidation atmosphere during melting and is directly related to the proportion of black heart defects within the brick.

Residual Shrinkage Control: The “No Shrinkage” (WS) grade employs directional solidification technology, resulting in a much higher proportion of dense zones compared to conventional casting.

Ultrasonic Testing Pass Rate: This provides a direct indication of the distribution of internal cracks and porosity. Most high-end projects require this report.

III. Which Bricks Are Used in Different Parts of a Glass Kiln? Examples of Zonal Configuration

Taking a 400-ton-per-day bottle and jar glass kiln as an example, a typical zoning scheme is as follows:

Liquid flow channel: AZS-41 shrinkage-free (WS), pre-assembled and shipped from the factory

Liquid Level Line: AZS-41

Main Tank Walls: AZS-36

Kiln Sill: AZS-36 or AZS-41

Chute Corner: AZS-36 Special-Shaped Bricks

Large Arch and Breast Wall: AZS-33 or High-Quality Sintered AZS

Central part of the regenerator: Low-porosity clay bricks combined with AZS-33

Pool bottom lining: AZS-33 or 36 (depending on glass type)

IV. How Long Do Electric-Fused Bricks Last? Key Factors Affecting Service Life

The design service life of a furnace is typically 8–15 years. The actual performance of electric-fused bricks depends on:

Glass type (High-alkali glass causes more severe erosion)

Liquid level temperature and fluctuation range

Proportion of cullet and degree of contamination

Whether the preheating ramp-up regimen is standardized (see dedicated article on preheating)

Whether there is localized overheating caused by electric fusing

For the same grade of electric fusing bricks, the annual erosion rate can vary by a factor of 2–3 between different suppliers, which underscores the necessity of establishing a supplier evaluation system.

V. How to Evaluate Chinese AZS Suppliers?

When overseas buyers search for “AZS refractory supplier China,” they often face information asymmetry. The recommended evaluation framework is as follows:

Does the factory possess full-chain production capabilities from raw materials to cold processing?

Does it have directional solidification casting lines and in-line flaw detection equipment?

Can it provide independent third-party erosion rate test reports?

Does it offer pre-assembly services and maintain video records?

Export experience and available overseas application case studies

Located in the Zhengzhou Refractory Materials Industrial Cluster in Henan Province, Chaoyu possesses end-to-end production capabilities and online full-inspection capabilities. The company has supplied electric fusion bricks and supporting solutions for glass kilns to markets in Southeast Asia, South Asia, and the Middle East.

VI. Why Can’t Pre-assembly and Preheating Be Skipped?

For irregular assemblies such as flow channels and feed ports, achieving a joint flatness of ±1 mm is difficult if they are manually ground and fitted on-site. Factory pre-assembly allows for simulation of hot-state alignment and marking of alignment lines, significantly reducing the risk of glass melt penetration. Similarly, the heating of AZS bricks must follow a step-by-step preheating protocol (ambient to 150°C → 600°C → 1100°C → operating temperature, with holding periods at each stage). Failure to do so may result in premature spalling due to improper release of residual stresses.

VII. How to Obtain Selection Support and Technical Documentation?

Chuangyu provides the following support to glass manufacturers: issuing zone-specific selection recommendations based on furnace drawings and glass types; providing product data sheets and third-party test reports; factory pre-assembly services for custom-shaped bricks in critical areas; and technical team participation in early-stage refractory material selection discussions.

To obtain the “Electric-Fused AZS Brick Grade Quick Reference Table” or selection recommendations for specific projects, please submit your request via the “Contact Us” page on this website.