Influence on Static Grain Growth and Sinterability of BaO Addition into 8YSZ

In this study, 8 mol.% yttria stabilized cubic zirconia (8YSZ) powders as a matrix material and 045 wt% BaO powders as an additive were used in order to determine the effect of BaO addition and amount on the microstructure, sintering and static grain growth properties of the 8YSZ. For these purposes, undoped and BaO-doped 8YSZ specimens were annealed for grain growth at 1400, 1500, and 1600 degrees C for 10, 50, and 100 h, respectively. An increase of annealing temperature and holding time resulted in grain growth in all specimens. The grain size of the 8YSZ decreased with the higher level of BaO added. A limited amount of BaO dissolved in 8YSZ, and insoluble BaO reacted with ZrO2 at high sintering temperature and generated the BaZrO3 second sphase compound. Energy dispersive X-ray spectroscopy results showed that the BaZrO3 second phase segregated at the surrounding grains and grain boundaries of the 8YSZ. These BaZrO3 second phases had a pinning effect at the grain boundaries and prevented the migration of the grain boundaries of the 8YSZ. In conclusion, the grain growth results showed that the grain growth in the BaO-doped 8YSZ specimens was controlled by a solid solution drag mechanism.