Chemistry And Physical Properties Of Fused Cast AZS Block

Fused cast AZS block is made from pure alumina powder and Zircon sand (composed of 65% zirconia and 34% SiO2). Fused cast AZS block is abbreviated as AZS because it contains Al2O3－ZrO2－SiO2.
The main chemical composition of fused cast AZS includes Al2O3(45%-50%), ZrO2(33%-41%), SiO2(13%-16%) and alkali metal oxides(Na2O+K2O, 1.3%-1.4%). According to the different content of ZrO2 from 33%-41%, fused cast AZS block can be divided into three types AZS—33#,AZS—36# and AZS—41#.
ZrO2 is preferably contained in a large amount with a view to improving the corrosion resistance. Al2O3 is an important component like ZrO2. Al2O3 constitutes corundum crystals. The corundum crystals exhibit strong corrosion resistance and have a characteristic that they show no abnormal expansion or shrinkage due to a temperature change. SiO2 is the main component for forming the network of the matrix glass. Na2O constitutes a structure for modifying the network of the matrix glass and exhibits an action to control the viscosity of the matrix glass and an action to inhibit formation of mullite. K2O is not an essential component, but shows the same action as Na2O. For cost reasons, the alkali metal oxide is preferably Na2O.
The crystal phase of fused cast AZS block consists of corundum, baddeleyite, eutectic phase of corundum and baddeleyite, glass phase and a small amount of mullite. Corundum has a high melting point. It is the stablest crystal phase of Al2O3. It presents a shape of rhombohedral cylindrical skeleton in AZS. Baddeleyite has a high melting point and stable chemical property. It is a kind of particulate mineral in the AZS. It presents a shape from ovate to droplet and is often clustered into a chain, herringbone, etc. A small amount of baddeleyite is dissolved in glass phase. It has the strongest corrosion resistance to glass melt. The glass phase has a low softening point. At a high temperature, it becomes liquid and exudes to the surface of the brick and leaves pores in the brick. The glass melt diffuses into the brick through the pores and aggravate the corrosion of brick. The mullite should be avoided as it will reduce the amount of corundum and baddeleyite.
Fused cast AZS block has a dense structure with a high bulk density (about 4.00g/cm3) and low apparent Porosity(1.0%-1.2%). It has high cold crushing strength(300 Mpa), high exudation temperature of glass phase (1400℃) and high refractoriness(1700℃). Its bubble separation ratio（1300℃×10h）is 1.0-1.2. It has strong corrosion resistance to glass melt and its anti-corrosion rate of glass liquid under 1500℃X36h（mm/24h）is 1.2%-1.4%.
Due to its strong glass corrosion resistance and high thermal shock stability, fused cast AZS block is widely used in the glass contact area and superstructure of glass furnaces.
Zhengzhou Sunrise is a refractory material supplier from China, offering high quality refractory materials for glass furnaces, including fused cast AZS block, fused cast alumina block, fused cast high zirconia block, mullite brick, zircon brick, alumina bubble brick, magnesia brick, sillimanite brick, corundum brick, low porosity fireclay brick, high alumina brick, all kinds of glass furnace ramming masses, etc..