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| Home > Publications database > Thermodynamic considerations concerning Chromium poisoning |
| Conference Presentation (Invited) | FZJ-2015-06184 |
2015
Abstract: One major degradation mechanism of SOFCs is the poisoning of the perovskite cathodes because of gaseous chromium species released from the metal interconnect and the tubing of the stack. Despite the major effort that has already been done in investigating the reaction mechanisms of chromium with the cathode materials in SOFCs, the connection between the cathode properties and the chromium deposition is still not completely understood.Due to its high electronic and ionic conductivity (La,Sr)(Co,Fe)O3 (LSCF) is one of the most commonly used cathodes for SOFCs in the temperature range of 700 – 800 °C. This material is favorable because of its intrinsically high electronic and ionic conductivity. One major drawback of LSCF is the segregation of SrO on the cathode particle surface. The reaction of SrO and volatile Cr-species in the gas phase lead to an insulating SrCrO4-phase. This layer decreases the electronic conductivity, hinders the gas transport through the porous cathode and blocks catalytic active sites for the oxygen reduction. The main challenge in describing the Cr-degradation of SOFCs is the amount of influencing parameters and how they are linked.As it’s one of the most important parameters, two ways to measure the Cr partial pressure and techniques to trap Cr from the gas phase will be described. Together with thermodynamic calculations, different types of model samples will be introduced as well.
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