Alumina-Zirconia-Silica Products

Fused-cast alumina-zirconia-silica products (AZS or Bacors) are the most common material for construction of glass melting furnaces (baths and critical areas of superstructure). A distinguished feature of AZS refractories is high glass-attack resistance, refractoriness, and durability. Use of fused cast refractories for constructing baths of glass melting furnaces enables application of glass melting temperatures within the range of 1500 to 1600 °C.

AZS refractories are Al₂O₃–ZrO₂–SiO₂ system products. The range of compositions of Bacor refractories containing from 33 to 41% ZrO₂ is determined by the position of ternary eutectic having melting point of 1765 °C.

Raw materials for Bacor production are zircon concentrate, alumina, and natural baddeleyite. The fused cast refractories manufacturing technology includes charge melting in an electric arc furnace, melt spouting into molds, annealing and machining of products.

The Bacor phase composition includes corundum and baddeleyite ZrO₂ crystals formed as a result of co-crystallization. When the melt solidifies, the sequence of crystalline phase hardening is as follows: baddeleyite® eutectic mixture of corundum with baddeleyite® corundum. As the content of ZrO₂ increases, individual crystals of baddeleyite are hardened. Refractory fused cast AZS products are manufactured under the following brands: BK-33, BK-37 and BK-41, which have the content of the main component (zirconium dioxide) of 33%, 37% and 41%, respectively.

AZS refractories are Al₂O₃–ZrO₂–SiO₂ system products. The range of compositions of Bacor refractories containing from 33 to 41% ZrO₂ is determined by the position of ternary eutectic having melting point of 1765 °C.

Raw materials for Bacor production are zircon concentrate, alumina, and natural baddeleyite. The fused cast refractories manufacturing technology includes charge melting in an electric arc furnace, melt spouting into molds, annealing and machining of products.

AZS refractories are characterized by the absence of permeable channel porosity: this feature excludes their impregnation with melt­. To a large extent, this fact determines high­ corrosion resistance when they come in contact with glass melts. Corrosion resistance of Bacor refractories increases with increase in ZrO₂ content. Thus, increase in the amount of ZrO₂ from 33% to 41% improves corrosion resistance at glass melting temperatures by 1.3 to 1.5 times.