TY - GEN
T1 - Mechanical properties of ceria based oxygen ionic conductors for SOFC
AU - Yugami, Hiroo
AU - Iguchi, Fumitada
AU - Sato, Kazuhisa
AU - Hashida, Toshiyuki
PY - 2008/12/1
Y1 - 2008/12/1
N2 - The fracture strength and creep rate of rear earth (Y and Gd) doped ceria are systematically studied from the viewpoints of dopant concentration, oxygen partial pressure and temperature dependences. Fracture strength and creep rate are measured by modified small punch test and four point bending method, respectively. From results of fracture test, the highest fracture strength is obtained on the samples sintered at 1600 °C for Y and Gd-doped CeO 2. The unique temperature dependence of fracture strength on doped CeO2 is observed. It shows the local minimal value at around 600 °C and the fracture strength increases with increasing temperature. The fracture surface structure drastically changes with changing temperature observed by SEM. Since we observed the close coincidence between the fracture strength and the ratio of transcrystalline fracture surface for all samples, it is concluded that the increase of fracture strength at high temperature in doped CeO2 can be attributed to the temperature dependence of transcrystalline fracture strength. Typical creep curves of 2, 5, 10 and 20 YDC were measured under constant load in air. The creep rate decreases with increasing the dopant concentration. From the analysis of creep properties, the creep is controlled by cerium vacancy diffusion and change of ceria vacancy concentration decreases creep rate.
AB - The fracture strength and creep rate of rear earth (Y and Gd) doped ceria are systematically studied from the viewpoints of dopant concentration, oxygen partial pressure and temperature dependences. Fracture strength and creep rate are measured by modified small punch test and four point bending method, respectively. From results of fracture test, the highest fracture strength is obtained on the samples sintered at 1600 °C for Y and Gd-doped CeO 2. The unique temperature dependence of fracture strength on doped CeO2 is observed. It shows the local minimal value at around 600 °C and the fracture strength increases with increasing temperature. The fracture surface structure drastically changes with changing temperature observed by SEM. Since we observed the close coincidence between the fracture strength and the ratio of transcrystalline fracture surface for all samples, it is concluded that the increase of fracture strength at high temperature in doped CeO2 can be attributed to the temperature dependence of transcrystalline fracture strength. Typical creep curves of 2, 5, 10 and 20 YDC were measured under constant load in air. The creep rate decreases with increasing the dopant concentration. From the analysis of creep properties, the creep is controlled by cerium vacancy diffusion and change of ceria vacancy concentration decreases creep rate.
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U2 - 10.1115/FuelCell2008-65206
DO - 10.1115/FuelCell2008-65206
M3 - Conference contribution
AN - SCOPUS:77952598195
SN - 0791843181
SN - 9780791843185
T3 - Proceedings of the 6th International Conference on Fuel Cell Science, Engineering, and Technology
SP - 85
EP - 91
BT - Proceedings of the 6th International Conference on Fuel Cell Science, Engineering, and Technology
T2 - 6th International Conference on Fuel Cell Science, Engineering, and Technology
Y2 - 16 June 2008 through 18 June 2008
ER -