Deposition of Chromium Species at Sr-Doped LaMnO[sub 3] Electrodes in Solid Oxide Fuel Cells: III. Effect of Air Flow

Deposition processes of chromium (Cr) species for the system chromia-forming alloy metallic interconnect/Sr-doped (LSM) electrode/3 mol % (TZ3Y) electrolyte have been investigated at 900°C with no air flow ( i.e. , the electrode was exposed to open air). With air flow, the deposition of Cr species took place preferentially at the TZ3Y electrolyte surface with the formation of and [S. P. Jiang, J. P. Zhang, L. Apateanu, and K. Foger, J. Electrochem. Soc. , 147 , 4013 (2000)]. Without air flow, Cr deposition processes at the LSM electrode are very different. Deposition of Cr species occurred on the TZ3Y electrolyte surface but also on the LSM electrode surface. Cr deposits were significantly higher on areas under the rib of the interconnect, compared to that under the channel of the interconnect. Elemental analysis shows that the composition of Cr deposits is most likely on the TZ3Y electrolyte surface and (La, Sr)(Cr, or (Cr, on the LSM electrode surface. The results demonstrate that the mechanism of Cr deposition at the LSM electrode is not affected by the air flow. However, the kinetics of the deposition process strongly depend on the flux of gaseous Cr species, which in turn are affected by the air flow and the cell configuration ( i.e. , the stack design).