Preparation And Performance Of Mullite Lightweight Materials

Lightweight ceramic materials prepared by foam method have high porosity. Poresin the material can effectively prevent heat loss, which have a good insulation effect.It’s very important to development low thermal conductivity and insulation effect goodlightweight insulation material, especially in today’s society, energy consumptionincreasing and energy crisis growing. Meanwhile the existence of large pores canreduce the use of materials, to achieve the purpose of saving material resources.The preparation of mullite insulating material by using andalusite as main rawmaterial was investigated in this paper. The effect of solid content, clay, microsilicaand cement on the rheological property of andalusite slurry were tested by rheometer.The mullitization of andalusite was characterized by X-ray diffractometer (XRD) andscanning electron microscope (SEM). In addition, the effect of volume-weight onlightweight materials performance was also studied. Through the modification ofMaxwell thermal conductivity model, new thermal conductivity model for this systemwas derived.The results show that: during the preparation of the slurry, the addition of clayincreased the slurry’s viscosity, which improved the stability of the slurry. When thesolid content was low(less than40%), the addition of microsilica will also increasedthe slurry’s viscosity and played a certain role on improving the stability of the slurry.The addition of cement had little effect on the slurry’s rheological property.The mullitization of andalusite started at1250℃, and it was severe at1350℃. Themullitization of andalusite could accomplish after sintering at1400℃×3h. With theincrease of the adding amount of foam, the samples’ volume-weight decreased. Withthe decrease of the samples’ volume-weight, samples’ total porosity and apparentporosity increased, and their closed porosity had little change, but their compressivestrength and average pore size decreased, and their sintering linear change rateincreased. Finally get the preparation techonlogy of different volume-weight gradientlightweight materials.Comprehensively considering the effect of porosity, pore shape and pore size onthermal conductivity model, thermal conductivity, which is suitable for this system,was obtained: λ1(1.402λ2+0.6λ1+(0.198λ2-0.6λ1)V)/(1.402λ2+0.6λ1-(0.33λ2-λ1)V...