Ferritic stainless steels are the most commonly used materials for solid oxide fuel cell interconnect application. Although these alloys may meet the criteria for interconnect application for short periods of service, their application is limited for long-term use (i.e., 40,000 h) due to poor oxidation behaviour that results in a rapid increase in contact resistance. In addition, volatile Cr species migrating from the chromia scale can poison the cathode resulting in a considerable drop in performance of the cell. Coatings and surface modifications have been developed in order to mitigate the abovementioned problems.
In this study, composite electrodeposition of reactive element containing particles in a metal matrix was considered as a solution to the interconnect problems. Nickel and Co were used as the metal matrix and LaCrO3 particles as the reactive element containing particles. The role of the particles was to improve the oxidation resistance and oxide scale adhesion, while the role of Ni or Co was to provide a matrix for embedding of the particles. Also, oxidation of the Ni or Co matrix led to the formation of conductive oxides. Moreover, as another part of this study, the effect of substrate composition on performance of steel interconnects was investigated.
Numerous experimental techniques were used to study and characterise the oxidation behaviour of the composite coatings, as well as the metal-oxide scale interface properties. Scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX), as well as surface analysis techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS), were used for the purpose of characterization. The substrate used for coating was AISI-SAE 430 stainless steel that is considered as a typical, formerly used interconnect material. Also, for the purpose of the metal-oxide scale interfacial study, ZMG232 stainless steel that is a specially designed interconnect alloy was used.
It is shown that the composite coatings greatly reduce the contact resistance and effectively inhibit Cr outward migration. In addition, it was determined that the presence of impurities in the steel, especially Si, and the absence of reactive elements drastically contribute to interconnect degradation. / Materials Science and Engineering
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/402 |
| Date | 11 1900 |
| Creators | Shaigan, Nima |
| Contributors | Dr. Douglas G. Ivey, ( Department of Chemical and Materials Engineering), Dr. Weixing Chen, (Department of Chemical and Materials Engineering), Dr. Qi Liu, (Department of Chemical and Materials Engineering), Dr. John Nychka, (Department of Chemical and Materials Engineering), Dr. Andre McDonald, (Department of Mechanical Engineering), Dr. Anthony Petric, (McMaster University) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 9848519 bytes, application/pdf |
| Relation | Nima Shaigan (2008). doi:10.1016/j.jpowsour.2008.06.065, Nima Shaigan (2008). doi:10.1016/j.jpowsour.2008.05.024, Nima Shaigan (2008). http://dx.doi.org.login.ezproxy.library.ualberta.ca/10.1149/1.2835204, Nima shaigan (2009). http://dx.doi.org.login.ezproxy.library.ualberta.ca/10.1149/1.3116252 |
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