Densification of 8 mol% yttria-stabilized zirconia at low temperature by flash sintering technique for solid oxide fuel cells

Flash sintering is novel, innovative, and promising technique for achieving highly dense ceramic materials at low furnace temperature and short sintering time. Herein, flash sintering process was studied by reducing furnace temperature while the electric field applied to samples was kept constant. Further, 8 mol% yttria-stabilized zirconia (8YSZ) samples were sintered by current-limiting flash sintering mode during the occurrence of this flash sintering process. Results showed that the lower the furnace temperature, the longer the time for the onset of flash sintering. However, temperature threshold was observed under certain electric field. Resulting flash sintered 8YSZ samples were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). SEM images exhibited well-dense microstructures with small grain size. EIS results indicated that the values of conductivity of all 8YSZ samples flash sintered at different furnace temperatures were almost similar, and the conductivity of 8YSZ flash sintered at 565 °C reached 0.056 S cm⁻¹ at 850 °C under the electric field of 300 V cm⁻¹, which is adequate for solid oxide fuel cells application.