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Durable Azs Fused Casting Alumina Zirconium Blocks for Glass Furnaces1
Refractory MaterialAzs Fused Alumina Zirconium BlocksDurable Azs Blocks
Henan Creat Lead Industrial Technology Co., Ltd
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Product Description Product DescriptionAZS Refractory Bricks & Blocks are produced from alumina powder, zirconia sand and additive. Zirconia content defines their corrosion resistance. AZS Fused Cast Refractories are the most widely used materials in glass melting furnaces, frit kilns and occasionally some foundry plants. AZS Refractory Bricks have low potential for stoning, blistering and exudation of the matrix glass. Therefore, most suitable for use in superstructures of melters, side walls of refiners, paving blocks, and forehearth channel blocks. According to the difference of Al2O3 contents, the AZS bricks usually are classified into the AZS33, AZS36 and AZS41 for your Selection.Our AZS fused alumina zirconium Corundum Brick products are made to tight dimensional tolerances and have an excellent load-bearing ability at higher temperatures. Our AZS fused alumina zirconium Corundum Brick retains most of its mechanical strength at elevated temperatures and exhibits very low levels of creep, making it the first choice for load-bearing applications in the range 1500oC to 1800oC.With the development of technology, reduction method has been replaced by oxidation method for fusing zirconium corundum refractories. Oxidation method for making AZS bricks is to use oxidizing atmosphere, it has feature that low carbon content and Variable valence oxide exist in high valence, low melting point impurities, it boost glass phase's temperature of exudation, which make baddeleyite's and glass phase's anti-erosion ability adequately work, thus improve glass furnace life. The main feature of oxidation method is to do decarburization for materials at the last fused stage. Common producing method is to blow oxygen from opening at top of furnace when furnace temperature reach to 2000 C, which can accelerate oxidizing reaction at liquid surface to assure production quality. With oxidation method using long arc heating at liquid surface, electric energy turned into thermal energy which melting solid materials, but arc light can not mix liquid or flow it, liquid inside electric furnace is in stationary state or just slight perturbance, which is not only difficult to eliminate low density impurities inside glass liquid, but also lead to zirconium sediment during melting process, which cause composition segregation and structure segregation between bricks. To conquer above disadvantages, by repeating practice, we invent Bubbling method and Bottom Oxygen Blowing method for fused refractories and obtained national patent for invention. Bottom Oxygen Blowing is to blow compressed air separated from oil and oxygen through air inlet hole between furnace shell and liner. Its advantage is: 1) Blowing oxygen into electric furnace don't need electricity, which solved the problem of furnace temperature reduction caused by power cut in existing oxygen blowing method, this method greatly reduce power consumption for producing electro-fused refractories and reduce production cost. 2) By continuously blowing oxygen to furnace, liquid flow and mix faster and completely, it makes carbon and Low-valent oxide easily react with oxygen, improve efficiency for decarburization and increase percentage of High-valent oxide. On the other hand, Bottom Oxygen Blowing make glass liquid more balance by reducing weight segregation due to volume-weight of zirconium dioxide higher than Al2O3 and SiO2. What's more, by expending oxygen blowing time, low melting point impurities and bubble floated, thus can make bricks low porosity and more solid, so that can lengthen working life. 3). Since producing process get simplified, melting process can be automatically control online. Detailed Photos Product ParametersItemUnitIndicatorAZS33-YAZS33PT-YAZS41-YAZS41PT-YChemical compositionAl2O3 %Remaining50.14 42.92ZrO232~3633.7440~4443.42Fe2O3 0.063 0.068TiO2 0.068 0.12CaO 0.064 0.06MgO 0.03 0.045K2O 0.049 SiO2 ≤ 16.5141311.98Na2O1.51.491.31.3Fe2O3+TiO2+3 2.5 CaO+MgO+Na2O+K2O+B2O3Fe2O3+TiO20.3 0.3 Volume Density (Dense Part)≥g/cm33.73.83.64.27Apparent porosity ≤%20.61.30.6Anti-Erosion speed in Static status(normal soda-lime glass 1500oC×36h)≤mm/24h1.6three phase boundary(mm/24h)1.451.3three phase boundary(mm/24h)1.12Down Surface 1/2(mm/24h)0.03 Down Surface 1/2(mm/24h)0.03Temperature of glass phase initial separated out≥oC1400140014001410Bubble separated rate (common soda-lime glass)≥%20.711Glass phase seepage(1500oC×4h)≤%measured data availableThermal Expansivity (1000oC) measured data available Capacity >PT,QX Kg/m33400 3550 ZWS3550 3800 WS3600 3850 Remark: Fit for matters unit weight exceed 50kgsApart from chemical composition, materials feature is also hinge on inner structure, which depends on producing condition and process. Common AZS refractories has three type: AZS33#,AZS36# and AZS41#, their chemical composition is in eutectic crystal of Al2O3-ZrO2-SiO2 phase equilibrium diagram. In theory, during fused refractories cooling, by temperature declining and degree of supercooling increased, primary zirconium crystal appeared in liquid phase. With chemical composition change, corundum phase will come up and on primary zirconium crystal, which form eutectic crystal structure in stratiform, meanwhile, based on different chemical composition, redundant AL2O3 separated out in form of a-corundum or b-corundum. Hence, electrofusion AZS materials always composed by zirconium, corundum, zirconium-corundum eutectic crystal and glass phase. zirconium, corundum, zirconium-corundum eutectic crystal has high melting point and stable chemical performance in high temperature, which is important constituent element of glass anti-erosion. Glass phase has lower melting point, easily appeared in liquid phase, after spilling out, will left micro hole, which will lead to liquid glass permeation, enlarge contact area between liquid glass and refractory materials, which exacerbate erosion and destruction for furnace. But during solidification process of fused zirconium corundum refractories materials, zirconium transformed from tetragonal crystal to monoclinic crystal and corundum transformed from b lattice to a lattice, which will cause volume expansion, due to the exist of low melting point glass phase, which left big space for crystalized zirconium and corundum, the defect of cracking caused by internal stress brought by volume change will be eliminate. Based on the fact of Al2O3-ZrO2-SiO2 ternary system including three binary system and the interval of crystallization temperature of Al2O3-ZrO2 binary system, the phase structure of fused zirconium corundum refractory materials shall be zirconium-corundum eutectic crystal which run through casting in dendritic shape while glass phase fill of interspace of dendritic crystal with function of agglomerant and buffering.To keep long designing life of glass furnace, designer select Zirconium corundum refractories with different quality based on furnace position. But in practice, most of furnace can not reach expected working life, excluding factors of design and usage, the problem mainly due to material quality on some part of some bricks, so that the whole furnace's life get limited. To assure furnace life, the refractories materials must be qualified.Due to limitation of casting methods and fused technical, the structure of fused zirconium corundum products often be ingredient segregation and structure segregation. Picture shows micro structure on different position of AZS 36# made by some factory, obviously, there are huge structural difference in different position. Besides of materials feature, such phenomenon is also caused by structure segregation from different cooling condition and chemical composition.In normal working process, glass phase inside of AZS bricks will be separated out by melting when glass furnace fired to 1400oC, leave eutectic crystal of porous Zirconium clinopyroxene and porous corundum, liquid glass will permeate into AZS bricks through pore, which will cause desquamation and erosion on AZS bricks. Since zirconium has high melting point and stable chemical performance under high temperature, if Zirconium clinopyroxene exist by even and tiny crystal phase inside of bricks and form compact eutectic structure together with corundum, which will stop desquamating of refractories. Hence, whether the zirconium can be evenly distributed in fused AZS or not, it is greatly important for glass furnace on anti-erosion. Our AdvantagesNoPoint of advantageAdvantage can lead to:1Excellent thermal conductivityMake your ceramic in excellent quality2More Clean than other materialsEasy to maintain your kiln production line.3Saving more energyReduce your cost.4Competitive PriceSave your cost
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