Determination of Cr and O diffusion coefficients in (Co,Mn)3O4 coatings for IT-SOFC Steel Interconnects
EMSL Project ID
30403
Abstract
The long term performance and performance stability of the intermediate temperature solid oxide fuel cells (IT-SOFC) are closely connected to the corrosion resistance and thermal stability of the metal interconnect in the SOFC stack. Many steel alloys being considered as potential SOFC interconnect material form surface chromia scales that provide a source of volatile Cr-rich species that enter the SOFC gas stream and ultimately poison the cathode electrode of the cell. Surface coatings on the interconnect have been found to significantly reduce the oxidation of the bulk alloy as well as minimize the Cr transport and poisoning of the electrode. Any thermally grown surface oxide or applied coating on the interconnect surface must also retain its mechanical integrity and electrical conductivity. In the proposed work a combination of experiments and computational modeling will be performed to characterize and understand the interface chemistry and electrical performance of manganese cobaltite spinel (Mn,Co)3O4 (MCO) coating being considered as one of the most likely solutions to the long term oxidation limitations of steel interconnects. The science team consisting of investigators from EMSL and Montana State University will fabricate MCO coatings with various microstructural characteristics using several deposition methods under consideration for this SOFC application. Appropriate depth-profiling techniques will be used to determine the diffusion coefficients for O and Cr through single- and poly-crystal MCO films, and will in turn allow for predictions of the oxide growth kinetics and interconnect lifetime. FIB/TEM measurements will serve to identify any correlation in spatial distribution of Cr ions and coating microstructure, such as grain boundaries. Computational modeling work will serve to identify the diffusion mechanisms and migration pathways for bulk MCO. Once the diffusion mechanisms in bulk MCO are determined, the influence of coating microstructure on the diffusion behavior can be better understood.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2008-08-04
End Date
2010-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Finsterbusch M, A Lussier, E Negusse, Z Zhu, RJ Smith, JA Schaefer, and YU Idzerda. 2010. "Effect of Cr2O3 on the O-18 Tracer Incorporation in SOFC Materials." Solid State Ionics 181(13-14):640-645. doi:10.1016/j.ssi.2010.03.007