Fused Cast AZS Blocks

AZS stands for Alumina-Zirconia-Silica, the three main oxides in the block. Fused cast AZS is produced by melting the oxide blend above 1800°C and casting it into dense, near-zero-porosity blocks. The zirconia content (33–41% ZrO₂) is what gives the exceptional resistance to molten glass corrosion that makes AZS the standard for glass furnace contact zones.

The number is the ZrO₂ percentage: AZS-33 has about 33% zirconia, AZS-36 about 36%, and AZS-41 about 41%. Higher zirconia means greater resistance to glass corrosion and higher density (3.4 to 4.0 g/cc), and higher cost. AZS-33 is used in superstructure, AZS-36 in sidewalls, and AZS-41 in the most aggressive throat and paving zones.

Void-free (VF) is a casting method that minimises the internal shrinkage cavity left when molten AZS solidifies. VF blocks release fewer defects (stones and blisters) into the glass, so they are specified for high-quality glass such as display, optical and tableware. Standard-cast types are used where glass quality tolerance is wider.

AZS blocks line the glass-contact zones of glass melting furnaces: tank sidewalls, bottom paving, throat, doghouse, superstructure and forehearth. They are chosen because they resist the aggressive corrosion of molten glass far better than bonded refractories, giving long campaign life between rebuilds.

Yes. Shanker Agencies supplies fused cast AZS blocks for glass furnaces. We advise on grade (33/36/41) and cast type (VF vs regular) based on your glass type, pull rate and the specific tank zone, and support furnace rebuild scheduling.