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Preparation and Performance Characterization of Alumina-based Light-weight Insulation Materials

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Tutor: LiYuanBing
School: Wuhan University of Science and Technology
Course: Materials Science
Keywords: light-weight insulation,foaming,alumina,corundum-spinel
Type: Master's thesis
Year:  2012
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With the continuous development of metallurgy, chemical industry and buiding materialsindustry, it is difficult for the traditional thermal insulation materials to meet the needs. Thedevelopment and application of high strength, ultra-light and low thermal conductivity insulationlining material becomes extremely important. The use of lightweight materials not only increasesthe regenerative effect of the furnace, but also reduces the weight of the furnace. In today¡¯senergy-scarce society, it has good prospects for the development and application. Currently,among a variety of insulation materials, the alumina insulation materials become importantbecause of the largest varieties, high service temperature and good energy-saving effect.In this work, alumina was used as the main raw material to prepare alumina light-weightinsulation materials by foaming, and the effect of different sintering temperature, differentcontent of foam and the starch on properties and microstructure of alumina light-weightinsulation materials was investigated; Then on the basis of the above, preparing corundum-spinellightweight insulation material by adding magnesia, The influence of the firing temperature,amount of foam, the content and particle size of fused magnesia as well as the content ofindustrial alumina corundum on the properties and microstructure of light-weight alumina-spinellightweight insulation materials was investigated, the following conclusions could be drawn:£¨1£© To alumina light-weight insulation material, with the increase of sintering temperature,the bulk density, linear shrinkage of sample increase gradually, but when the sinteringtemperature is too low, the strength of the sample is low, so the optimal sintering temperature is1550¡ãC; With the increase of foam, the bulk density decrease, but the strength of the sample willbe reduced accordingly, integrating all aspects of performance, the appropriate foam addition is1200mL/kg. The right amount of starch can cure the foam slurry to improve the strength ofgreen body, but it have no obvious effect on the improvement of the porosity, the optimumamount is6wt%.£¨2£©To corundum-spinel light-weight insulation materials, it has good physical propertiesfired at1550¡ãC; The density of the specimen can be controlled by the addition of foam, butwhen the foam is added more, it would cause the linear shrinkage of Specimen increases and theintensity decreases, the appropriate foam addition is600mL/kg; With the increase of magnesiaaddition, the bulk density of the resulting corundum-spinel light-weight insulation materialsdecreases, but the strength decrease first and increase later, due to the volume expansion effectcaused by reaction of alumina and magnesia; Meanwhile, the linear change rate change from-3.5%to0.15%, The thermal conductivity is significantly reduced by the addition of fusedmagnesia, which change from0.542W/£¨m¡¤K£© to0.29W/£¨m¡¤K£© at300¡ãC, the optimal content offused magnesia is15wt%; With the increase of fused magnesia grain size, the density and strength of the sample increase, and the linear change rate gradually decrease, when the particlesize is0.088-0.2mm, the products have better integrated performance; With the increasing ofindustrial alumina, the density of the specimen decreases first and then increases later, the linearexpansion rate has the same trend with density, when the content of industrial alumina is30wt%,the density and linear expansion rate of the sample get the minimum0.91g/cm3and0.41%g/cm3respectively.£¨3£©With the optimization of production technology and mix-proportion, alumina lightweightinsulation materials could be prepared with the properties: bulk density1.25-1.8g/cm3, coldcrush strength19-40Mpa, thermal conductivity¡Ü0.9W¡¤m-1¡¤K-1£¨900¡ãC£©; Corundum-spinellight-weight insulation materials: bulk density0.8-1.2g/cm3, cold crush strength2-12Mpa,thermal conductivity0.266-0.342W¡¤m-1¡¤K-1£¨900¡ãC£©.
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