Proposal of a Modified Four-Point Bending Method for Determining Interfacial Fracture Energy at Electrode/Electrolyte Interfaces in SOFCs

摘要

This study proposes the use of all-ceramic modified four-point bending specimens consisting of a thin porous electrode layer sandwiched between two dense electrolyte beams to determine the fracture energy of the electrolyte/electrode interface. The sandwich arrangement was effective to prevent the premature vertical cracking of the electrode and to eliminate the use of polymeric adhesives for metallic stiffeners which restricted the testing temperature range. The experiments conducted at room temperature using the all-ceramic layered specimens demonstrated that the proposed four-point bending method successfully induced delamination between the electrode and electrolyte producing the characteristic plateau behavior in the load-displacement records and enabled the interfacial fracture energy to be evaluated based on the load level at the plateau. The interfacial fracture energies were determined to be 5.6 J/m~2 for the interface of NiO-8YSZ/3YSZ and 0.8 J/m~2 for LSCF6428/8YSZ using the identical testing method and specimen configuration.