Fracture of Porous Ceramics: Application to the Mechanical Degradation of Solid Oxide Cell During Redox Cycling
Résumé
A model based on the Phase Field approach has been developed to simulate the local fracture in porous electrode microstructures. The model capacity to predict the crack nucleation and propagation has been studied with theoretical considerations. For the model validation, micro-compression tests have been performed on porous YSZ micro-pillars. As expected, the compressive fracture strength has been found to decrease with the material porosity. Moreover, a transition in fracture mode has been detected from a brittle behavior toward a local damage when increasing the porosity. It has been shown that the model is able to reproduce correctly the experimental results. The validated model has been used to simulate the fracture of the YSZ backbone induced by the Ni re-oxidation in a typical Ni-YSZ cermet. The generation and localization of the micro-cracks have been discussed according to the degree of Ni re-oxidation and the local morphology of the electrode microstructure.
Origine : Fichiers produits par l'(les) auteur(s)