NAME: Sumako TSUJI

Title:Effects of Microstructure on The Fracture Toughness and Electrical Resistivity of Sintered Samaria-Doped Ceria


Supervisor: Kazunori SATO �@


SDC (Ce0.8Sm0.2O1.9) is the most promising electrolyte for solid oxide fuel cells due to its high oxide-ion conductivity. This research has mainly focused on
the fracture toughness of sintered SDC bodies, which is affected by the microstructure formed during the sintering process. SDC disks sintered above approximately 1400 degrees Celsius showed an almost constant relative density of 98%. However, their microstructures were significantly affected by the sintering temperature and time. The fracture toughness of dense SDC disks whose relative density is higher than 98% showed a decrease with decreasing the average grain size and increasing the number of closed pores. The grain-boundary resistivitiy of dense SDC showed the maximum at the average grain size of approximately 2.5 ��m, although the bulk resistivity showed the constant value regardless of the average grainsize. This phenomenon is probably related to the microstructure of the grain-boundary region.