关键词: 高岭土;莫来石;轻量;微孔;铝硅摩尔比

Abstract: Lightweight microporous mullite aggregates (LMMA) were prepared via an in-situ decomposition pore-forming route using kaolin powder and α-Al2O3 powder as the raw materials.The effect of Al2O3/SiO2 molar ratio and firing temperature on their structure and properties was investigated.The results showed that strong diffraction peaks of mullite were found in the alumina-rich sample together with corundum after firing at 1400-1600 ℃,whereas only mullite phase was found in the other samples;Microporous structures of as-prepared LMMA and pore sizes in the range of 0.1 to 4 μm were detected in all samples;With increasing the firing temperature,both of bulk density and compressive strength increased,whereas apparent porosities showed an opposite tendency.The bulk density of alumina-rich sample was 2.49 g/cm3,its apparent porosity and compressive strength were 25.6％ and 146 MPa,respectively,after firing at 1500 ℃.The silica-rich sample and the one which had a Al2O3/SiO2 molar ratio of 3∶2 possessed bulk densities lower than 1.95 g/cm3,apparent porosities higher than 38％,their thermal conductivities at 1000 ℃ were 0.76 W/(m · K).

Key words: kaolin;mullite;lightweight;microporous;Al2O3/SiO2 molar ratio