The behavior of nickel and silver in a simulated solid oxide fuel cell environment

Nickel, silver, and a nickel-silver composite have been tested in a simulated solid oxide fuel cell interconnect environment. The susceptibility of the interconnect to mechanical degradation as a result of environmental attack has been analyzed. The experimental results of this study demonstrate that silver is unstable in the interconnect environment, while nickel remains stable. A finite difference model has been developed to analyze how the simultaneous diffusion of hydrogen and oxygen into the interconnect can result in the nucleation of water vapor bubbles. In addition, a model developed by Raj and Ashby to describe the growth of cavities under creep conditions has been employed to predict the rate at which cavity growth will occur. Finally, a Ni-Ag composite was fabricated and studied as an interconnect in an attempt to avoid the mechanical degradation that occurs in silver, while maintaining a path for electrical conduction that is not degraded by oxidation.