CHENG Ziqiang, CHEN Yanxinyu, ZHAO Yongsong, SHAO Haoran, ZHOU Dayu
(School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024, Liaoning, China)

Abstract: The effects of freezing rate, slurry concentration and freezing method on microstructure and anisotropy of mechanical properties of TiO₂ porous ceramics were studied. With increasing concentration of slurry (10–25 vol.%), both porosity and average interlayer spacing of the porous ceramics were decreased. The freezing rate mainly affects the average interlayer spacing by varying the growth mode of ice crystals. In the bidirectional freezing casting process, cross-sectional orientation of the porous ceramics tends to be more consistent with increasing wedge angle. With increasing slurry concentration and freezing rate, the Vickers hardness and compressive strength of the TiO₂ porous ceramics in different directions are increased as a whole, but the increase degree in different directions is different, as the wedge angle increases (0°–20°) and the anisotropy of the compressive strength of the porous ceramics becomes more prominent, which is increased from 12.15 to 64.91 MPa in x direction. The TiO₂ porous ceramics have great application potential in the fields of biological bone tissue materials and ceramic filters.
Key words: titanium dioxide; freeze casting; microstructure; mechanical properties; anisotropy