Preparation Of Calcium Feldspar With Magnesium Slag - Alumina Porous Thermal Insulation Material Research

Magnesium slag of a factory of Shanxi, Yangquan kaolin and industrialalumina (mass fraction94%) as the main raw material, polyvinyl alcohol (PVA)as binder, sinter anorthite-alumina porous insulation materials using the methodof the normal pressure to sintering the green molded body.This paper studied the contents:The different sintering temperatures affect the physical properties (bulkdensity, apparent porosity, linear shrinkage), the phase compositions and thecrystal morphologies of anorthite-alumina porous insulation materials.The different holding times influence in some degree the physicalproperties (bulk density, apparent porosity, linear shrinkage) and the crystalmorphologies of anorthite-alumina porous insulation materials.The different heating rates have some impacts to physical properties (bulkdensity, apparent porosity, linear shrinkage) and the crystal morphology ofanorthite-alumina porous insulation materials.The amount of the binder of PVA take some changes to the physicalproperties (bulk density, apparent porosity, linear shrinkage), thermal shockresistance, the phase composition and crystal morphology of anorthite-aluminaporous insulation materials.Experimental results show that:Sintering temperature of1350℃~1370℃is more appropriate forthematerial with the bulk density1.52g/cm3, line shrinkage about2%and theapparent porosity60%. The main crystal phases are anorthite and alumina. Asthe temperature increased, anorthite rhoptry grains grew from2μm to10μm.And the same time, the alumina grains were precipitated and grew gradually.Holding times have a certain impact on the physical properties and crystalmorphology of anorthite-alumina porous insulation materials. As the holdingtime being extended, the materials had the bulk density increased from1.50g/cm3to1.53g/cm3, linear shrinkage increased from2.7%to4.2%and apparentporosity reduced from60%to57%. The rhoptry anorthite grains grew up to5μm in2h, and then did not change with the holding time changing. The alumina grain gradually precipitated and attached to the aggregates more andmore with the time.Heating rates have little influence in the physical properties and crystalmorphology of anorthite-alumina porous insulation materials with the bulkdensity1.52g/cm~31.531g/cm3, linear shrinkage3.6%to4.2%and apparentporosity from57to61%. Grain sizes and morphologies were fewer changeswith the heating rates.With the binder PVA contents increased from0%to12%, anorthite-alumina porous insulation material had the bulk density from1.52g/cm3to1.55g/cm3, linear shrinkage rate from3.2%to4.0%and apparent porosity reducedfrom67%to59%. Main crystal phases are anorthite and alumina with the grainsizes were5μm. However the grains gradually become from point contacts toface contacts each other. The materials with the binder PVA had better thermalshock performance as the formation of pores slowing down the micro-crackspropagation.