A study on the factors involved in collapse of macroporous α-Al2O3 structure

Collapse is the major problem in preparing macroporous ceramics by the polymeric sponge method. The contributions of slurry viscosity, slurry-solid loading and heating rate to collapse are analyzed. The viscosity of slurry should be the highest possible before this parameter prevents slurry entry to all parts of the sponge. Higher viscosity leads to more solid particles of α-Al2O3 being taken into the sponge and this is required to avoid collapse prior to and during sintering. Heating rate is another important factor controlling collapse. To maintain pore structure, a controlled slow heating at the beginning of sintering program is needed.