Porous mullite/alumina layered composites with gradient porosity

Porous three-layer mullite/alumina composites with a gradient in porosity and pore size were produced by a tertiary-butyl alcohol ice template technique. The porous products sintered at 1300–1500°C showed two types of pores, i.e. interconnected, unidirectional macro-pore channels and micrometre sized pores in the walls surrounding the pore channels. The layered materials showed superior compressive strength when compared with monolithic blocks, possibly due to the development of alternating layered structure with a gradient porosity and crack deflection along interlayer.