Modeling Microstructure Evolution of Ni Cermet Using a Cellular Automaton Approach

Abstract

The degradation of SOFC electrodes is often determined by their microstructure changes. It is desirable that the microstructure evolution of electrodes in service can be simulated in 3-D for real materials so that the changes in their electrochemical performance can be predicted. This involves changes in important parameters such as: electronic and ionic conductivities; TPB (triple phase boundary) density and connectivity; and tortuosity of condensed phases and porosity. In this contribution a new cellular automaton (CA) approach to simulating complex microstructure evolution is presented, which is based on free energy reduction by using an interface imbalanced interaction model. The approach is validated first in 2-D examples to reproduce wetting between two solids and grain boundary grooving, which shows the new approach is fully consistent with classical theories. The approach is then applied to simulation of the evolution of a real 3 dimensional microstructure of a Ni-YSZ cermet fuel cell anode. The modeling results show that the microstructure evolution is sensitive to the wettability of Ni on YSZ and that a good wettability is helpful in maintaining a slower coarsening rate and smaller reduction of electrode performance. © 2014 The Electrochemical Society. All rights reserved.