Coated Ferritic Stainless Steels as Interconnects in Solid Oxide Fuel Cells
Licentiate thesis, 2013
Solid oxide fuel cells (SOFCs) have gained increased research interest as they are
promising devices for a decentralized and clean electricity and heat production. Several
material challenges have to be solved to reach sufficient efficiencies and life times.
One important aspect are ferritic stainless steels as interconnect materials which are
corrosion resistant, mechanically stable and cost optimized. This work is aimed to
investigate economic solutions for interconnect materials and understand the underlying
degradation mechansims. Two substrates, the commercial available steel AISI 441
and the ferritic stainless steel optimized for an SOFC application Sandvik Sanergy
HT, were combined with different barrier coatings and exposed in cathode atmosphere.
The ferritic stainless steel AISI 441 coated with different reactive element and reactive
element/cobalt coatings was investigated concerning corrosion resistance and
chromium volatilization. Uncoated 441 suffered from severe corrosion, which was successfully
improved by coatings of cerium and lanthanum. Cerium/cobalt-coated AISI
441 was showing excellent and promising properties for a interconnect application.
Sandvik Sanergy HT coated with novel conversion coatings of copper with manganese
or iron was examined in a similar way. Coatings of copper and iron improved the
corrosion and chromium evaporation properties significantly and were promising for
further developments. In contrast did copper combined with manganese as coating
on Sandvik Sanergy HT not result in an improvement in corrosion properties and