The mostly applied type of refractory in the glass industry, in direct contact with the glass melt, is fused cast AZS block.
Zirconia is a very insoluble oxide in most glass melts and therefore has great corrosion resistance. However, in addition to being very expensive, zirconia has a tendency to crack during manufacture and use, and is very difficult to make in large shapes. Zirconia is therefore combined with oxides, usually alumina and silica, to descrease the solubility of the composite refractory.
The fused cast AZS block is produced by melting the raw materials in an electric arc furnace at about 2200-2400 ℃. The melt is treated with oxygen to oxidize zirconium oxy-carbo-nitride or other reduced constituents, produced by the reaction with the graphite electrodes during melting. The molten material is then cast into molds to, or very near to, the final shape of the block desired. The mold with the fused cast ceramic is cooled down very slowly in order to anneal (free of thermal stresses) the fused cast product.
The fused cast AZS block is available in a number of grades, principally distinguished by zircon content: 33#, 36# and 41#. Among the three, 33# and 41# are most widely used. For the most severe applications, the 41# is recommeded. For less severe applications, 33# is used.
The AZS fused cast 33# block contains 33% ZrO2. It is unlikely to cause defections of stones, blisters and cords. Therefore, it is most suitable for superstructures of melters, side walls of refiners, paving blocks, and forehearth channel blocks.
The AZS fused cast 36# block contains 36% ZrO2. It is corrosion resistant and shows minimal contamination against molten glass. It is most suitable for glass contact parts of melters, and has shown considerable results in side walls and paving blocks.
The AZS fused cast 41# block contains 41% ZrO2. It is highly corrosion resistant against molten glass, and by strengthening matrix glass, it shows minimal contamination to molten glass. It is most suitable for glass melting furnaces; on throats of parts that demand high corrosion resistance, dog house corner blocks, electrode blocks, bubbler blocks and electric furnaces.
The AZS fused cast block from Sunrise Refractory has passed the ISO international certified. High purity raw material, scientific formula, advanced technology and professional guide all contribute to our qualified azs blocks production.