Fabrication of gradient pore TiO2 sheets by a novel freeze-tape-casting process

Gradient pore structure TiO2 sheets were fabricated by a novel freeze-tape-casting process. Aqueous TiO2 ceramic slurries were prepared by the traditional tape-casting processing and were then cast onto an aluminum foil carrier. The slurries were immediately frozen on the substrate, whose temperature was about -18 degrees C. After freezing completely, the green sheets were then dried in a lyophilizer. Freeze-tape casting led to formation of a gradient pore microstructure of the TiO2 sheet. The results showed that the solid loading of slurry considerably affected the pore microstructure, pore morphology, and the porosity. Solid loadings of 10, 20, 30, 40, and 50 wt% slurries were used, respectively, and the gradient pore structure TiO2 sheets with different porosities of 75%-88% were obtained.