On the High-Temperature Oxidation and Area Specific Resistance of New Commercial Ferritic Stainless Steels

• Main Authors: Valeria Bongiorno, Roberto Spotorno, Daniele Paravidino, Paolo Piccardo
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Metals
• Subjects: FSSs; IT-SOFCs stacks; high-temperature oxidation; ASR; interconnects
• Online Access: https://www.mdpi.com/2075-4701/11/3/405

Two commercial ferritic stainless steels (FSSs), referred to as Steel A and Steel B, designed for specific high-temperature applications, were tested in static air for 2000 h at 750 °C to evaluate their potential as base materials for interconnects (ICs) in Intermediate Temperature Solid Oxide Fuel Cell stacks (IT-SOFCs). Their oxidation behavior was studied through weight gain and Area Specific Resistance (ASR) measurements. Additionally, the oxide scales developed on their surfaces were characterized by X-Ray Diffraction (XRD), Micro-Raman Spectroscopy (μ-RS), Scanning Electron Microscopy, and Energy Dispersive X-Ray Fluorescence Spectroscopy (SEM-EDS). The evolution of oxide composition, structure, and electrical conductivity in response to aging was determined. Comparing the results with those on AISI 441 FSS, steels A and B showed a comparable weight gain but higher ASR values that are required by the application. According to the authors, Steel A and B compositions need an adjustment (i.e., a plain substitution of the elements which form insulant oxides or a marginal modification in their content) to form a thermally grown oxide (TGO) with the acceptable ASR level.