Abstract
Metallic interconnects in solid oxide fuel cell (SOFC) stacks are often in direct contact with a nickel/yttria stabilized zirconia
(Ni/YSZ) cermet anode. Interdiffusion between the two components may occur at the operating temperature of 700–850◦C. The
alteration of chemical composition can result in phase transformation of the steel and in formation of oxides with a poor electrical
conductivity in the anode. In this study, the area specific resistance (ASR) of the steel Crofer 22 APU, in contact with a Ni/YSZ anode
with and without a tape casted CeO2 barrier layer was measured in simulated SOFC anode conditions at 800◦C. The microstructure
in the contact area was characterized using scanning electron microscopy techniques. The ASR was low for the steel in direct contact
with the Ni/YSZ anode. Nickel diffusion into the steel resulted in a fine grained zone, which was identified as ferrite. The zone
is austenitic at the exposure temperature but transforms to ferrite during cooling. When a CeO2 nickel diffusion barrier layer was
used The ASR was considerably higher. These results imply that nickel diffusion is not only detrimental: It leads to microstructural
instability but also results in a low electrical resistance of the anode/interconnect contact.
Original language | English |
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Journal | Journal of The Electrochemical Society |
Volume | 162 |
Issue number | 4 |
Pages (from-to) | 387-396 |
ISSN | 0013-4651 |
DOIs | |
Publication status | Published - 2015 |