Growth Mechanisms and Electrical Conductivity of Oxide Scales on Ferritic Steels Proposed as Interconnect Materials for SOFC's
✍ Scribed by P. Huczkowski; N. Christiansen; V. Shemet; L. Niewolak; J. Piron-Abellan; L. Singheiser; W. J. Quadakkers
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 672 KB
- Volume
- 6
- Category
- Article
- ISSN
- 1615-6846
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✦ Synopsis
Abstract
The oxidation behaviour of two ferritic steel variants was studied at 800 °C in air and the results were compared with data obtained for two Cr‐based materials. The mechanisms of scale formation were investigated for oxidation times ranging from a few minutes up to 6,000 hours. A number of conventional analysis techniques such as optical metallography, scanning electron microscopy, and X‐ray diffraction were used for scale characterization, in combination with two‐stage oxidation studies using an ^18^O‐tracer. It was found that the growth rates of the scales on the two steels were not only governed by the main scale forming alloying elements, Cr and Mn, but to a substantial extent by minor additions of Si and Al. At the test temperature of 800 °C these latter elements affect scale formation, although they are not directly incorporated in the surface scales. Independent of a detailed alloy composition, the conductivities of the scales on the ferritic steels were found to be higher than those of the surface scales formed on the Cr‐based materials studied.