Analysis of residual stress for thin-layered electrolyte co-sintered with porous electrodes applied in solid oxide cells

Abstract

In this study, a trans-scale modeling approach, non-contact high-temperature deformation measurement and flattening compression testing technique are developed and applied for co-sintered thin-layered electrolyte with thick porous electrodes, aiming to comprehensively analyze residual stress and sintering deformation with/without flattening force during/after manufacturing process (including the sintering and flattening process). Coefficient of thermal expansion (CTE) and elastic modulus (E) are first predicted by the Molecular Dynamics method, which together with predicted microscopic volume changes along cell length direction are applied in the finite element modeling for macroscale deformation and residual stress prediction. The results show that the current prediction by the varied CTE and E for sintering deformation is improved by 14 % compared to that using constant ones. The application of a flattening force (31 N, determined from the displacement-compressive force curve) can be effective in reducing cambered deformation (a reduction of 20.14 %), but can also lead to a redistribution of the flattening residual stress within the cell. The stress concentration at the corners of the anode and electrolyte layers is heightened, whereas the flattened residual stress in the electrolyte layer region adjacent to the anode side is diminished. Further identification and optimization of the key parameters relating to the sintering process are conducted which reveals that the sintering temperature has the most significant impact on the sintering displacement, while the larger sintered cambered displacement requires a bigger flattening force to achieve the targeted displacement.