1997 Volume 105 Issue 1217 Pages 37-42
Fine zirconia powders doped with 3 to 6mol% Sc2O3 have been prepared by the urea-based homogeneous precipitation method using monoclinic zirconia sols previously formed by the hydrolysis of ZrOCl2 solution. Highly dense Sc2O3-doped tetragonal zirconia ceramics, Sc-TZP (>99%) with a homogeneous microstructure were obtained by sintering these powders at 1300°C or 1400°C for 1h and their phase stability was investigated. The average grain size and the crystal phase of ZrO2(+Sc2O3) materials were observed to depend on the Sc2O3 contents. Addition of 3.5mol% Sc2O3 was necessary to fabricate zirconia bodies consisting of fully tetragonal phase by sintering at 1300°C. This value corresponds to nealy 1.5 times the content of Y2O3 in the ZrO2-Y2O3 system. The average grain size of the 4mol%Sc-TZP sintered at 1400°C was <0.5μm. Although the grain size is depending on the sintering temperature, it increased gradually with increases in Sc2O3 content from 3 to 6mol% and in the content of the cubic phase. The monoclinic zirconia contents transformed from the tetragonal phase in the surface of the 4 to 6mol% Sc-TZP under hydrothermal conditions at 180°C for 50h were about 93 to 70%.
