Sintering, Grain Growth, and Phase Composition of Gd₂O₃-Stabilized ZrO₂ Powders

The influence of Gd 2O 3 concentration on the sintering, grain growth, and phase composition of ZrO 2 solid solutions was investigated. Powders of ZrO 2 containing 4-20 mol% Gd 2O 3 were synthesized by a co-precipitation method and calcined at 900 °C to produce a solid solution. Sintering studies on powder compacts performed at a constant heating rate of 5 °C/min to 1450 °C indicate that the tendency for sintering exhibits a maximum at a Gd 2O 3 concentration of 8 mol% but decreases for the lower and higher Gd 2O 3 concentrations. Grain growth data obtained after annealing dense samples for 1 h at 1400 °C show a similar trend in which the maximum grain size occurs at a concentration of 8 mol%. Except for the composition containing 12 mol% Gd 2O 3, the measured densities of hot-pressed samples are in good agreement with a rule of mixtures. Inadequate densification and a tendency towards microcracking during cool-down from the hot pressing temperature are responsible for the lower density of the ZrO 2-12 mol% Gd 2O 3 sample. The sintering, grain growth, and phase composition data are compared with those for a baseline ZrO 2 composition containing 4 mol% Y 2O 3