This study aims to demonstrate a general process for the fabrication of macroporous oxide/metal composite foams through aqueous gelcasting of Pickering emulsions. Composite of yttria-stabilized zirconia/titanium (ZrO2/Ti) was selected as the model material. The process involves tuning of wettability of the ZrO2 particles through selective adsorption of organic sodium bis(2-ethylhexyl) sulfosuccinate on the particle surface so that the hydrophobic ZrO2 particles were able to reside preferentially at the air–water interface during mechanical foaming. The hydrophilic Ti particles, on the other hand, were designed to ‘‘stay” between the ZrO2-stabilized bubbles to form struts of the foam together with the ZrO2 particles not attached at the interface. Composite foams of binary particulate mixtures were then shaped into desired geometries by freeze gelcasting in which addition of agar was used as the shape-setting agent to avoid phase segregation due to the density and wettability difference. Porous ZrO2/Ti composite foams of various ZrO2:Ti ratios were prepared. Typically, the sintered ZrO2/Ti compacts with a porosity ranging from 78% to 82% and a bimodal pore-size distribution (0.01–0.3 and 20–90 lm, respectively) were obtained. Their pore structure, phase distribution, and mechanical strength were determined by mercury porosimetry, electron microscopy, electron probe micro-analyzer, and three-point bend test, respectively.
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