GRAIN-GROWTH CONTROL IN NANOCRYSTALLINE OXIDE CERAMICS

Amorphous to nanocrystalline ZrO2-CeO2 alloy powders were prepared by chemical precipitation, and uniaxially pressed at 4 GPa. Sintering at 1300 degrees C (maximal shrinkage temperature) for 2.5 hrs in air was followed by grain growth between 1000 degrees C to 1600 degrees C, and for 2 to 20 hrs. The evolution of the final density and grain size to gether with the measured activation energies are in agreement with the structural model of nanocrystalline grain clusters. According to this model, densification proceeds with negligible grain growth below the maximal shrinkage temperature.