Title: Model-based prediction of the ohmic resistance of metallic interconnects from oxide scale growth based on scanning electron microscopy
Authors : Linder, Markus
Hocker, Thomas
Holzer, Lorenz
Friedrich, K. Andreas
Iwanschitz, Boris
Mai, Andreas
Schuler, J. Andreas
Published in : Journal of Power Sources
Issue : 272
Pages : 595
Pages to: 605
Publisher / Ed. Institution : Elsevier BV
Issue Date: 2014
Language : Englisch / English
Subjects : Scale growth rate law; Interconnect; Map; Solid oxide fuel cell (SOFC)
Subject (DDC) : 530: Physik
621.3: Elektrotechnik, Elektronik
Abstract: The increase of ohmic losses caused by continuously growing Cr2O3 scales on metallic interconnects (MICs) is a major contribution to the degradation of SOFC stacks. Comparison of measured ohmic resistances of chromium- (CFY) and ferritic-based alloy (Crofer) MICs at 850 °C in air with the growth of mean oxide scale thicknesses, obtained from SEM cross section images, reveals a non-trivial, non-linear relationship. To understand the correlation between scale evolution and resulting ohmic losses, 2D finite element (FE) simulations of electrical current distributions have been performed for a large number of real oxide scale morphologies. It turns out that typical morphologies favor nonhomogeneous electrical current distributions, where the main current flows over rather few “bridges”, i.e. local spots with relatively thin oxide scales. These current-“bridges” are the main reason for the non-linear dependence of ohmic losses on the corresponding oxide scale morphology. Combining electrical conductivity and SEM measurements with FE simulations revealed two further advantages: it permits a more reliable extrapolation of MIC-degradation data over the whole stack lifetime and it provides a method to assess the effective electrical conductivity of thermally grown Cr2O3 scales under stack operation.
Departement: School of Engineering
Organisational Unit: Institute of Computational Physics (ICP)
Publication type: Beitrag in wissenschaftlicher Zeitschrift / Article in scientific Journal
DOI : 10.1016/j.jpowsour.2014.08.098
ISSN: 1547-5905
URI: https://digitalcollection.zhaw.ch/handle/11475/1635
Appears in Collections:Publikationen School of Engineering

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