Yttria doped zirconia has been widely employed as electrolyte materials for solid oxide fuel cells (SOFCs). Plasma spraying is a cost-effective process to deposit YSZ electrolyte. In this study, the 8 mol % Y 2 O 3 stabilized ZrO 2 (YSZ) layer was deposited by low pressure plasma spraying (LPPS) and atmospheric plasma spraying (APS) with fused-crushed and agglomerated powders to examine the effect of spray method and particle size on the electrical conductivity and gas permeability of YSZ coating. The microstructure of YSZ coating was characterized by scanning electron microscopy and X-ray diffraction analysis. The results showed that the gas permeability was significantly influenced by powder structure. The gas permeability of YSZ coating deposited by fused-crushed powder is one order lower in magnitude than that by agglomerated powder. Moreover, the gas permeability of YSZ deposited by LPPS is lower than that of APS YSZ. The electrical conductivity of the deposits through thickness direction was measured by potentiostat/galvanostat based on three-electrode assembly approach. The electrical conductivity of YSZ coating deposited by LPPS with fused-crushed powder of small particle size was 0.043 S × cm-1 at 1000°C, which is about 20% higher than that of APS YSZ with the same powder.

Y 2 O 3 stabilized ZrO 2 (YSZ) coating is widely applied to the electrolyte layer in solid oxide fuel cell. With regard to the application of YSZ coating to solid oxide fuel cell, the electrical conductivity of YSZ coating is of essential importance. In this study, YSZ coating was deposited by plasma spraying using a sinter-crushed powders containing 4.5mol% Y 2 O 3 . The electrical conductivity of the coating at both directions parallel and perpendicular to the coating surfaces was measured by a direct current approach. The measurement was carried out at a temperature range from 600 °C to 1000 °C. The effect of spray distance on the electrical conductivity was also examined. The test showed that 4.5YSZ layer yielded the electrical conductivities of 2.2 s·m-1 and 4.3 s·m-1 at a temperature of 1000 °C in both direction perpendicular and parallel to the coating surface, respectively. It is clear that the electrical conductivity of the coating was lower than the identical sintered bulk material. The electrical conductivity of YSZ coatings in this study was of one-fifth to one-fourth in perpendicular direction and about one-half in parallel direction compared with the sintered YSZ bulk. It was considered that the lower electrical conductivity of the coating compared with the identical sintered bulk results from the lamellar structure with the limited interface bonding.