Effect Of Various Amount Of A1_2O_3 Addition On The Flexural Strength, Fracture Toughness And Hardness Of c-ZrO_2/Al_2O_3 Composites Used As An Electrolyte For Solid Oxide Fuel Cell

摘要

Cubic zirconia is widely used as an electrolyte for solid oxide fuel cells (SOFCs), because the material possesses high level of oxygen-ion conductivity and exhibits desirable chemical stability in both oxidizing and reducing atmospheres. However, the mechanical properties of cubic zirconia arc not sufficient to apply to an electrolyte in SOFC. Therefore, it is necessary to improve the mechanical properties of cubic zirconia to guarantee the lifetime and the reliability of the SOFC. In the present study, the effect of Al_2O_3 additions on the hardness, flexural strength and fracture toughness of c-ZrO_2/Al_2O_3 composites was investigated using fine-grained 8 mol% yttria-stabilized cubic zirconia (c-ZrO_2) doped with 0-10 wt% Al_2O_3. The addition of Al_2O_3 enhanced the hardness, flexural strength and fracture toughness of c-ZrO_2/Al_2O_3 composites. The maximum values obtained for hardness, flexural strength and fracture toughness were 1459 kg/mm~2, 330 MPa and 2.41±0.02 MPa/m~(1/2), respectively for the specimen containing 10 wt% Al_2O_3 while these values were 1314 kg/mm~2, 275 MPa and 1.5 ± 0.03 MPa/m~(1/2) for monolithic c-ZrO_2.