Chromium Deposition And Poisoning Between Metallic Interconnects And Cathode For Solid Oxide Fuel Cells

The Cr poisoning mechanism has been investigated by the interaction between theLa_0.9Sr_0.1MnO₃（LSM） cathode and Fe-Cr alloy interconnect. The poison effect on cathodeis observed by a group of orthogonal experiments at the presence of Fe-Cr alloy involvingwith air flow of100mL min^-1and current passages of400mA cm^-2at750°C. After thecurrent polarization, the cathode layer has been delaminated from the electrolyte （YSZ）,and the Cr deposition reaction is accelerated with adding air partial pressure. The resultssuggest that the deposition of Cr species would preferentially occur at the three phaseboundary region because of the CrO₃react with O ion. And the deposit sediments maygrow to be agglomeration in long time operation. The results of the EDS indicate the maincomposition of Cr₂O₃. In comparison, the deposit sediment in800°C with air flow of100mL min^-1and current passages of400mA cm^-2comprise by （Cr,Mn）₃O₄spinel grainbecause of the high electrochemical activity of the LSM cathode. The Cr poisoning isrelatively weaker between the Ni-Cr-Mo alloy with the Cr content of12.24%and thecathode as the polarization resistance of the half-cell remains stable in most time of thetest. The test by the Fe-Cr alloy with the Cr content of14%act strongly in the initial stageand the value of polarization resistance increases sharply, but as the time continued, theparameters of the electrochemistry polarization steady reduces in the rest time. And theFe-Cr alloy with the Cr content of16.65%has a weak influence on the cathode until thecathode delamination happened when the electrode potential became unstable. After thecathode delamination completed, the electrochemistry polarization steady reduces. Thedifferent action by these alloy is caused by the different element constitute.