Effect of valeric acid on the agglomeration of zirconia particles and effects of the sintering temperature on the strut wall thickness of particle-stabilized foam

Highly porous zirconia ceramics were prepared utilizing a particle-stabilized direct foaming technique in which the hydrophilic characteristic of zirconia particles was altered by the in situ adsorption of valeric acid on its surface. These surface modified zirconia particles are irreversibility adsorbed at the air/water interface and create an armor coating around the bubbles to stabilize them. In this study, the foamability and stability of zirconia foam were investigated by varying the valeric acid concentration, and zirconia foam with a foam volume of approximately four times the colloidal system volume was successfully prepared. The sintered foam has cell size ranging from 50 to 150 μm and the pore structure was characterized by mercury porosimetry. The effects of the sintering temperature on the grain size, strut wall thickness, and tetragonal phase were studied and correlated with an increase in the mechanical strength to 3.5 MPa with porosity of more than 90%.