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@PHDTHESIS{AsensioJimenez:133849,
author = {Asensio-Jimenez, Cristina},
title = {{E}ffect of {C}omposition, {M}icrostructure and {C}omponent
{T}hickness on the {O}xidation {B}ehaviour of {L}aves
{P}hase {S}trengthened {I}nterconnect {S}teel for {S}olid
{O}xide {F}uel {C}ells ({SOFC})},
volume = {204},
school = {RWTH Aachen},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2013-02240},
isbn = {978-3-89336-935-5},
series = {Schriften des Forschungszentrums Jülich Reihe Energie $\&$
Umwelt / Energy $\&$ Environment},
pages = {210 S.},
year = {2014},
note = {RWTH Aachen, Diss., 2013},
abstract = {The high-Cr, Laves phase strengthened ferritic steel,
Crofer 22 H, has recently been proposed as construction
material for interconnects in solid oxide fuel cells (SOFC).
Aim of the present investigation was to get more insight in
the details of SOFC relevant properties, mostly oxidation
behaviour and oxide electronic conductivity, in simulated
SOFC service environments as a function of temperature, with
main emphasis on themost commonly used operating temperature
800 °C. The present studies of Crofer 22 H, showed that the
consumption of chromium from the alloy as a result of
chromia surface scale formation ends up in formation of a
subsurface layer in which the Laves phase is depleted. In
parallel, formation of a thin zone near the scale/steel
interface occurs in which the Laves phase is enriched.
Modeling revealed that this depletion/enrichment process can
be explained by the influence of chromium concentration on
the niobium activity in the alloy matrix. Moreover,
experiments with solution annealed and pre-aged materials
showed that the subsurface phasetransformation processes are
at least partially affected by preferential Laves-phase
nucleation at the scale/steel interface. Experimental
results and theoretical considerations show that the
specimen/componentthickness dependence of the oxidation rate
is related to relaxation of oxide growth stress by creep of
the metallic substrate. Due to poor intrinsic creep
resistance, thin Crofer 22 APU specimens exhibit enhanced
oxidation rates in air at 800 °C. For the more creep
resistant steel Crofer 22 H this only occurs after Laves
phase coarsening which results in a substantial decrease in
intrinsic creep strength of the alloy. The resistance of
thethinnest samples against substantial creep deformation
then becomes gradually too small to prevent substantial
relaxation of oxide growth stress, leading to enhanced
oxidation rates. However, in anode gas hardly any
specimen/component thickness dependence of the oxidation
rate was found, which is believed to be related to a
different oxide scale composition and microstructure.},
keywords = {Dissertation (GND)},
cin = {IEK-2},
cid = {I:(DE-Juel1)IEK-2-20101013},
pnm = {123 - Fuel Cells (POF2-123)},
pid = {G:(DE-HGF)POF2-123},
typ = {PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/133849},
}