Use of SOFC metallic interconnect coated with spinel protective layers using the APS technology (Englisch)

The use of metallic interconnects for SOFC (solid oxide fuel cell) application leads to the problem of Cr migration. In order to avoid the cathode poisoning, spinel type coatings were developed and deposited using APS (atmospheric plasma spraying) on the cathode contact side of a ferritic interconnect. A second porous contact layer was deposited on the top of the dense protective one to favour the contact with the cathode and re-heal the possible stress caused by the difference in TEC (thermal expansion coefficients) between cell and interconnect. The deposition method selected to get a porous contact layer was the WPS (wet powder spraying). This study shows the behaviour of a single repeated unit, i.e. cell and interconnect, tested under a current density of 0.42 A/cm² at 800 deg C during 600 h. The interconnect ASR (area specific resistance) measured showed a decrease during the first hours, due to a conditioning process, reaching a low stable value after some hours. Post mortem analysis of both the cell and the interconnect confirmed the effectiveness of this coating against Cr poisoning.