Microstructure and properties of the inter-locked corundum/mullite structure

Inter-locked corundum/mullite (ICM) structure was prepared by the TBA (tert butyl alcohol)-based gel-casting method. The ICM structure was constructed by inter-locked corundum platelets and tiny amount of mullite. In the structure formation process, inter-locked topaz structure first formed in the fluorine-catalyzed gas-phase reaction at lower temperature. The topaz rods transformed into hexagonal corundum platelets at 900–1100 °C. The corundum platelets were inter-locked with each other in a stable way. Tiny amount of mullite formed in the structure at 1300–1500 °C. The volume density, apparent porosity, thermal conductivity and compression strength of the ICM structure (prepared at 1500 °C) were 0.561 g/cm3, 79.8%, 0.2530 W/m k and 0.56 MPa, respectively, making it promising candidate for heat-insulation.