Abstract
Chromium poisoning is a well-known degradation mechanism
in solid oxide fuel cell (SOFC) stacks. Stainless steel
interconnects (IC) have been identified as a major source
of chromium. Additionally, depletion of chromium in very
thin IC plates can lead to destructive break-away
oxidation. This calls for protective coatings to inhibit
the evaporation of chromium from the IC plates and to
improve the SOFC stack durability. Such coatings should
have a low electric resistivity and high physical and
chemical stability in high temperatures. Much literature
has been published on the performance of coatings.
However, comparison between them is difficult due to the
wide range of testing conditions. This work contributes
to the field by comparing coating solutions from
different companies and research centres, manufactured by
different methods. The evaluated coatings include
manganese-cobalt-iron and cerium-cobalt protective
layers. The developed coatings build on previous work
within the SCoReD2.0 project. Thin steel samples of
AISI441, Sandvik Sanergy HT and Crofer 22 H were used as
substrates. These steels were chosen since they are
commercially available and widely used in SOFC
applications. Area specific resistance (ASR) and overall
stability were investigated with a measurement setup that
mimics the conditions found in SOFC stacks. The steel
samples were placed on top of thin palladium foils with a
screen-printed lanthanum-strontium-cobalt (LSC) layer.
The measurement setup replicates the interactions at an
SOFC cathode since the LSC layer is manufactured the same
way as real cathodes. In addition, the use of palladium
spacers instead of steel enables electron microscopy
analysis of chromium migration into the LSC layer as well
as of oxide scale growth. ASR measurements were carried
out in a humid air atmosphere at 700 °C for 1000 hours.
The paper compares the protective coatings in terms of
ASR, chromium retention and overall stability and
discusses their usability in SOFC stacks.
This work has been conducted within the SCoReD2.0
project, which has received funding from the European
Union's Fuel Cells and Hydrogen Joint Technology
Initiative under contract no. 325331. Additionally, the
NELLHI (grant agreement no. 621227) and INNO-Sofc (grant
agreement no. 671403) projects are acknowledged.
Original language | English |
---|---|
Number of pages | 11 |
Publication status | Published - 2016 |
Event | 12th European SOFC & SOE Forum 2016 - Lucerne, Switzerland Duration: 5 Jul 2016 → 8 Jul 2016 |
Conference
Conference | 12th European SOFC & SOE Forum 2016 |
---|---|
Country/Territory | Switzerland |
City | Lucerne |
Period | 5/07/16 → 8/07/16 |