The grain growth in silica-doped 3-mol%-yttria-stabilized tetragonal zirconia polycrystals (SiO2-doped 3Y-TZP) and undoped 3Y-TZP has been examined in the temperature range of 1400°-1800°C. The presence of a SiO2 phase inhibits rather than promotes the grain growth in 3Y-TZP, particularly at high temperatures. During the grain growth in 3Y-TZP, yttrium ions are partitioned between grains, and the grain growth mechanism can be understood from Ostwald ripening dominated by lattice diffusion of cations. In SiO2-doped 3Y-TZP, an amorphous SiO2-rich phase exists only in the grain-boundary corners or junctions, not in the grain-boundary faces. The grain growth in SiO2-doped 3Y-TZP is controlled by using different mechanisms below and above the eutectic temperature of the zirconia-silica (ZrO2-SiO2) system. The glass phase does not have a major role in grain growth below the eutectic temperature, and the grain growth is dominated by a similar mechanism in undoped 3Y-TZP. The grain growth is more effectively retarded by the presence of a SiO2 phase above the eutectic temperature and is likely to be controlled by a solution-reprecipitation process in the amorphous phase at the grain-boundary corners or junctions.
|ジャーナル||Journal of the American Ceramic Society|
|出版ステータス||Published - 1998 8|
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