The long-term durability of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF)-coated Fe-Cr-Al alloy was investigated as a novel current collector material for SOFCs. The LSCF coating and subsequent heat-treatment at 700–900◦C changed the microstructure of the surface oxide layer to a columnar structure of nanosize γ-Al2O3 arranged in the same direction, in which a small amount of Sr3Al2O6 contributes to the electronic conduction. The LSCF coating decreased the alloy oxidation rate by 23% at 700◦C compared to the case without coating, following the parabolic growth law. Raising the temperature from 700◦C to 900◦C increased the oxidation rate of the LSCF-coated alloy by 51 times. The oxidation mechanism at 900◦C was considered to be similar to that at 700◦C, because of the similarity in microstructure, crystal structure, elemental composition and electrical conductivity. It was estimated that the Cr2O3 layer begins to grow on the inner side after roughly 6,000 h at 700◦C, when the thickness of the surface oxide layer exceeds 1 μm. The same γ-Al2O3 columnar microstructure still covered the surface after 12,000 h. However, further improvement in durability and electrical conductivity is needed to meet the requirements for practical application.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry