Effect of sintering process on the microstructures of Bi2O3-doped yttria stabilized zirconia

Variations of microstructures in Bi2O3-doped yttria stabilized zirconia (YSZ) with conventional furnace and microwave sintering were investigated in this work. The results demonstrated that a small amount of addition of Bi2O3 was effective in reducing the sintering temperature of YSZ from 1500 °C to 1200 °C and promoting the densification rate of the ceramics. It is interesting that microwave sintering is found to suppress the evaporation rate of Bi2O3 and formation of the monoclinic-ZrO2 or other amorphous phases. Compared to conventional furnace sintering, significant improvement in density of Bi2O3-doped YSZ at lower sintering temperatures with microwave sintering was observed. Rapid heating rate and short sintering time for restricting serious segregation at grain boundary were observed as well. Employing microwave sintering at the same sintered condition, the density of a specimen was evidently increased by 4.59% in comparison to the specimen sintered with a conventional furnace sintering.