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Accelerated creep in solid oxide fuel cell anode supports during reduction

Frandsen, H. L.; Makowska, M.; Greco, F.; Chatzichristodoulou, C.; Ni, D. W.; Curran, D. J.; Strobl, M. LU ; Kuhn, L. T. and Hendriksen, P. V. (2016) In Journal of Power Sources 323. p.78-89
Abstract

To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. The creep of reduced Ni-YSZ anode support at operating conditions has been studied previously. In this work a newly discovered creep phenomenon taking place during the reduction is reported. This relaxes stresses at a much higher rate (∼×104) than creep during operation. The phenomenon was studied both in three-point bending and uniaxial tension. Differences between the two measurements could be explained by newly observed stress promoted reduction. Finally, samples exposed to a small tensile stress (∼0.004... (More)

To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. The creep of reduced Ni-YSZ anode support at operating conditions has been studied previously. In this work a newly discovered creep phenomenon taking place during the reduction is reported. This relaxes stresses at a much higher rate (∼×104) than creep during operation. The phenomenon was studied both in three-point bending and uniaxial tension. Differences between the two measurements could be explained by newly observed stress promoted reduction. Finally, samples exposed to a small tensile stress (∼0.004 MPa) were observed to expand during reduction, which is in contradiction to previous literature. These observations suggest that release of internal residual stresses between the NiO and the YSZ phases occurs during reduction. The accelerated creep should practically eliminate any residual stress in the anode support in an SOFC stack, as has previously been indirectly observed. This phenomenon has to be taken into account both in the production of stacks and in the simulation of the stress field in a stack based on anode supported SOFCs.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Chemo-mechanical coupling, Creep, Ni-YSZ, Reduction, SOEC, SOFC
in
Journal of Power Sources
volume
323
pages
12 pages
publisher
Elsevier
external identifiers
  • scopus:84969567686
ISSN
0378-7753
DOI
10.1016/j.jpowsour.2016.04.097
language
English
LU publication?
yes
id
7ac794f9-7a76-4d61-8758-8d85035a0a92
date added to LUP
2016-09-27 09:34:58
date last changed
2017-06-25 04:54:33
@article{7ac794f9-7a76-4d61-8758-8d85035a0a92,
  abstract     = {<p>To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation, the stress field in the stack must be known. During operation the stress field will depend on time as creep processes relax stresses. The creep of reduced Ni-YSZ anode support at operating conditions has been studied previously. In this work a newly discovered creep phenomenon taking place during the reduction is reported. This relaxes stresses at a much higher rate (∼×10<sup>4</sup>) than creep during operation. The phenomenon was studied both in three-point bending and uniaxial tension. Differences between the two measurements could be explained by newly observed stress promoted reduction. Finally, samples exposed to a small tensile stress (∼0.004 MPa) were observed to expand during reduction, which is in contradiction to previous literature. These observations suggest that release of internal residual stresses between the NiO and the YSZ phases occurs during reduction. The accelerated creep should practically eliminate any residual stress in the anode support in an SOFC stack, as has previously been indirectly observed. This phenomenon has to be taken into account both in the production of stacks and in the simulation of the stress field in a stack based on anode supported SOFCs.</p>},
  author       = {Frandsen, H. L. and Makowska, M. and Greco, F. and Chatzichristodoulou, C. and Ni, D. W. and Curran, D. J. and Strobl, M. and Kuhn, L. T. and Hendriksen, P. V.},
  issn         = {0378-7753},
  keyword      = {Chemo-mechanical coupling,Creep,Ni-YSZ,Reduction,SOEC,SOFC},
  language     = {eng},
  month        = {08},
  pages        = {78--89},
  publisher    = {Elsevier},
  series       = {Journal of Power Sources},
  title        = {Accelerated creep in solid oxide fuel cell anode supports during reduction},
  url          = {http://dx.doi.org/10.1016/j.jpowsour.2016.04.097},
  volume       = {323},
  year         = {2016},
}