This study reports the tailoring of the microstructure of porous ceramics from particle stabilized colloidal suspension with the addition of starch by direct foaming. The initial colloidal suspension of Al2O3-SiO2 was partially hydrophobized by surfactant, propyl gallate (2 wt.%) to stabilize wet foam with the addition of SiO2 as stabilizer. The influence of the starch consolidation and solid content on the bubble size, pore size and pore distribution in terms of the contact angle, surface tension, adsorption free energy and Laplace pressure are discussed in this paper. The results show the wet foam stability of more than 85% corresponds to a particles free energy of 2.6 × 10−12 J and pressure difference of 6.0 mPa for colloidal particles with 1.25 wt. % of starch content. The uniform distribution of tri-modal micro pores were controlled by increasing starch contents and thick struts (films in wet foams), which led via higher stability wet foams to porous ceramics.

Keywords: Colloidal suspension, Starch, Wet foam stability, Tailoring microstructure, Porous ceramics