Influence of microstructure on nano-mechanical properties of single planar solid oxide fuel cell in pre- and post-reduced conditions

The present work investigates, both the macro- and nano-mechanical properties of all the three component layers e.g., anode, cathode and electrolyte of a planar single solid oxide fuel cell (SOFC). The flexural fracture strength experiments in three point bending mode are employed in both pre- and post-reduced conditions to study the macro-mechanical failure behavior of the single cell. Further, the nanoindentation technique is utilized in both pre- and post-reduced conditions to evaluate the nanomechanical properties e.g. nanohardness, Young’s modulus, mean contact pressure, relative stiffness and relative spring back at scale in both pre- and post-reduced conditions. The nanohardness and Young’s modulus of the pre-reduced anode are considerably degraded after reduction as NiO gets converted to Ni. However, as expected; those of the pre-reduced electrolyte and cathode are only slightly decreased after reduction because there are no chemical conversions involved. Further, the experimentally obtained data of nanomechanical properties, is explained with the application of the well established Weibull statistics as the microstructures with characteristically present pores and defects are highly heterogeneous in nature. The characteristic values of the various nanomechanical properties are analyzed using Weibull distribution for the anode, electrolyte and cathode layers of the SOFC in both pre- and post-reduced conditions.