加水分解 : 均一沈殿法によるZrO_2-Sc_2O_3系正方晶ジルコニア焼結体の調製と相安定性

概要

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Fine zirconia powders doped with 3 to 6 mol% Sc_2O_3 have been prepared by the urea-based homogeneous precipitation method using monoclinic zirconia sols previously formed by the hydrolysis of ZrOCl_2 solution. Highly dense Sc_2O_3-doped tetragonal zirconia ceramics, Sc-TZP ( >99% ) with a homogeneous microstructure were obtained by sintering these powders at 1300℃ or 1400℃ for 1h and their phase stability was investigated. The average grain size and the crystal phase of ZrO_2 ( + Sc_2O_3) materials were observed to depend on the Sc_2O_3 contents. Addition of 3.5 mol% Sc_2O_3 was necessary to fabricate zirconia bodies consisting of fully tetragonal phase by sintering at 1300℃. This value corresponds to nealy 1.5 times the content of Y_2O_3 in the ZrO_2-Y_2O_3 system. The average grain size of the 4 mol% Sc-TZP sintered at 1400℃ was < 0.5μm. Although the grain size is depending on the sintering temperature, it increased gradually with increases in Sc_2O_3 content from 3 to 6 mol% and in the content of the cubic phase. The monoclinic zirconia contents transformed from the tetragonal phase in the surface of the 4 to 6 mol% Sc-TZP under hydrothermal conditions at 180℃ for 50h were about 93 to 70%.
社団法人日本セラミックス協会の論文
1997-01-01