Synthesis and Sintering of Titania-Containing Tetragonal Zirconia Powders
Hironobu KUSANAGI, Takeshi SHIONO and Yasunori OKAMOTO
Abstract:In order to synthesize t-ZrO2 containing TiO2 as a stabilizing agent, two kinds of ZrO2 precursors were prepared by coprecipitation method. One was TiO2-ZrO2 system with the compositions of 5`20mol% of TiO2 and the other was CeO2-TiO2-ZrO2 system with the compositions of total 20mol% of TiO2 and CeO2. Synthesized precursors were calcined at 800C and then sintered at 1450C for 3h. In the binary system, t-ZrO2 phase was observed in calcined powders at any content of TiO2. Formation of t-ZrO2 increased with increasing addition of TiO2, and the calcined powder with 18mol% TiO2 was composed of only tetragonal phase at room temperature. For the sintered bodies of the calcined powders, however, t-ZrO2 phase could not be retained, regardless of TiO2 content. For 5`10mol% TiO2, they are composed of only m-ZrO2 phase, and for 15`20mol% TiO2, m-ZrO2/ZrTiO4 composites were obtained. Tetragonal zirconia polycrystal (TZP) could not be obtained. In the ternary system, t-ZrO2 phase was also obtained by calcination of precursors at any content of TiO2 and CeO2. The sintered body consisted of only t-ZrO2 phase by using the powder with 10mol% TiO2 and 10mol% CeO2. The polycrystal has the relative density of approximately 98%. Key Words:Tetragonal zirconia, Sintering, Solid solution, Titania, Coprecipitation method