TY  - JOUR
AU  - Garcia-Fresnillo, L.
AU  - Patel, R.
AU  - Niewolak, Leszek
AU  - Quadakkers, W. J.
AU  - Hua, M.
AU  - Wang, Q.
AU  - Meier, G. H.
TI  - Oxidation Behaviour and Phase Transformations of an Interconnect Material in Simulated Anode Environment of Intermediate Temperature Solid Oxide Fuel Cells
JO  - Materials at high temperatures
VL  - 34
IS  - 1
SN  - 1878-6413
CY  - Amsterdam [u.a.]
PB  - Elsevier Science
M1  - FZJ-2016-07238
SP  - 61 - 77
PY  - 2016
AB  - The oxidation behaviour and the phase transformations associated with high temperature exposure of a commercial ferritic interconnect steel, Crofer 22 H, was studied in a simulated solid oxide fuel cell (SOFC) anode atmosphere at 700 °C. Special emphasis was placed on the formation of the intermetallic sigma phase. No sigma phase was detected in the bulk alloy after 500 h of exposure of bare specimens. However, specimens which were pre-coated with a layer of nickel showed formation of an interdiffusion zone after as little as 2 h of exposure and sigma phase formation occurred after 10 h. The presence of the nickel layer, which simulates the contact between ferritic steel interconnects and a nickel mesh in a SOFC results in the formation of an austenitic zone and accelerated formation of a σ-phase rich layer at the ferrite/austenite interface. The ferritic steel is transformed into austenite due to the inward diffusion of nickel, σ-phase started to nucleate at the transformed austenite grain boundaries. The nucleation is enhanced by an increased Cr/Fe-ratio at that interface due to more pronounced diffusion of Fe, compared to Cr, in the direction of the Ni-layer. Different possible mechanisms for the nucleation and growth of σ-phase were identified. The experimental results led to the conclusion that sigma nucleates in the austenite and grows following an isothermal eutectoid-like decomposition.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000389473300008
DO  - DOI:10.1080/09603409.2016.1244373
UR  - https://juser.fz-juelich.de/record/824680
ER  -