Phase Field Modeling of Cubic to Tetragonal Transformation in YSZ and its Effect on Ionic Conductivity Degradation and Mechanical Damages

Abstract

During the high-temperature operation of solid oxide fuel cells (SOFCs), the degradations of electrolyte material yttria-stabilized zirconia (YSZ) in both ionic conductivity and mechanical strength can be caused by the cubic to tetragonal phase transformation. In this work, microelasticity phase field model is built to simulate the YSZ phase transformation considering the effects of grain boundary and solid morphology. The YSZ skeleton in real SOFC anode is reconstructed using focused ion beam-scanning electron microscopy (FIB-SEM) dual-beam technique. The ionic conductivity degradation and the mechanical damages under external mechanical loads of brittle YSZ phase in anode are investigated based on the phase field simulation results. The simulation results may provide theoretical guidelines for improving the SOFC anode during fabrication.