Fabrication of porous ceramics with controlled pore size by colloidal processing

Well-defined macroporous ceramics consisting of TiO2 and ZrO2 have been fabricated by two methods. One is via a template-assisted colloidal processing technique and the other is via a hetero-coagulation of template/ceramic particle colloidal processing. The former technique is as follows. Close-packed polymer spheres were first prepared as a template using centrifugation or gravitational sedimentation, followed by infiltration with alkoxide precursors. Then the removal of the template beads was achieved by calcination of the organic-inorganic hybrids at appropriate temperatures, yielding well-ordered macroporous ceramics. The latter technique is as follows. Core-shell composites of polymer/ceramic were obtained by mixing the oppositely charged two suspensions via electrostatic attraction following by filtration and calcination to produce macroporous ceramic materials. SEM images revealed that macroporous TiO2 and ZrO2 with ordered and uniform macropores have been obtained by both procedures.