Effect of Porogenic Agents on Properties of Microporous Mullite Aggregates

Microporous mullite aggregates were prepared from bauxite by dry pressing and firing at 1 700 ℃ for 3 h with corn starch,PMMA microspheres or rice husk powder as the porogenic agent.The effects of some porogenic agents and their additions(mass fraction of 0,5％,10％,15％and 20％,respectively)on the properties of the microporous mullite aggregates were analyzed by XRD,SEM and Image-Pro Plus software.The results show that the comprehensive performance of the sample with 10％rice husk powder is the best:the closed porosity is 7.1％;the bulk density is 2.63 g·cm-3;the compressive strength is 122 MPa;the median pore size is 15.16 μm;aandtthe thermal conductivity at 500 ℃ is 2.30 W·m-1·K-1.