TY  - JOUR
AU  - Grünwald, Nikolas
AU  - Sebold, Doris
AU  - Sohn, Yoo Jung
AU  - Menzler, Norbert H.
AU  - Vaßen, Robert
TI  - Self-healing atmospheric plasma sprayed Mn 1.0 Co 1.9 Fe 0.1 O 4 protective interconnector coatings for solid oxide fuel cells
JO  - Journal of power sources
VL  - 363
SN  - 0378-7753
CY  - New York, NY [u.a.]
PB  - Elsevier
M1  - FZJ-2017-06486
SP  - 185 - 192
PY  - 2017
AB  - Dense coatings on metallic interconnectors are necessary to suppress chromium poisoning of SOFC cathodes. Atmospherically plasma sprayed (APS) Mn1.0Co1.9Fe0.1O4 (MCF) protective layers demonstrated reduced chromium related degradation in laboratory and stack tests. Previous analyses revealed strong microstructural changes comparing the coating's as-sprayed and operated condition. This work concentrates on the layer-densification and crack-healing observed by annealing APS-MCF in air, which simulates the cathode operation conditions. The effect is described by a volume expansion induced by a phase transformation. Reducing conditions during the spray process lead to a deposition of the MCF in a metastable rock salt configuration. Annealing in air activates diffusion processes for a phase transformation to the low temperature stable spinel phase (T < 1050 °C). This transformation is connected to an oxygen incorporation which occurs at regions facing high oxygen partial pressures, as there are the sample surface, cracks and pore surfaces. Calculations reveal a volume expansion induced by the oxygen uptake which seals the cracks and densifies the coating. The process decelerates when the cracks are closed, as the gas route is blocked and further oxidation continues over solid state diffusion. The self-healing abilities of metastable APS coatings could be interesting for other applications.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000411544300023
DO  - DOI:10.1016/j.jpowsour.2017.07.072
UR  - https://juser.fz-juelich.de/record/837607
ER  -