Cr Vaporisation and Oxidation Behaviour of SUS430 Stainless Steel in the Simulated Cathodic Environment of Solid Oxide Fuel Cells
Joelle Chia Wen Mah, Muhamad Isyraf Aznam, Andanastuti Muchtar, Mahendra Rao Somalu, Mariyam Jameelah Ghazali
The migration of volatile Cr species from the metallic interconnects to the cathode material affects the long-term performance, stability, and durability of solid oxide fuel cells (SOFCs). This study aimed to elucidate the formation of oxide scale layer on a commercially available SUS430 stainless steel in a simulated cathodic environment of SOFCs. In addition, the effects of Cr vaporisation on the electrical properties of pelletised La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode were determined. A dual-layer oxide scale consisting of Cr2O3 (inner layer) and (Mn,Cr)3O4 (outer layer) formed on the steel substrates subjected to 200 h of oxidation showed insignificant effects on electrical properties. The trace of SrCrO4 and Cr2O3 species detected on the pelletised LSCF cathode confirmed Cr vaporisation from the steel substrates. An increment of approximately 38.8% in activation energy of the LSCF cathode was related to the formation of SrCrO4 and Cr3O4 species that reduced the concentration of oxygen vacancies and catalytic activities in the LSCF. Therefore, SUS430 stainless steel can only be used as SOFC interconnect material after the Cr vaporisation phenomena are effectively suppressed.