Effect of Ti Addition on Oxidation Behavior and Area Specific Resistance of Fe-20Cr Alloys for SOFC Interconnects

Abstract:

In this work, the oxidation behavior of Fe-20wt.%Cr alloys with different titanium contents: 0, 0.5, and 1 wt.% are studied as a function of time in air atmosphere. The samples were isothermally oxidized at 700°C for 24, 48, and 96 h in a box furnace. The area specific resistance of oxides formed at the alloys surface during oxidation is measured by four-point probe methods at 700°C for 24 h. For Ti containing alloys, surface morphology observation by SEM shows that a few of TiO₂ particles formed on the top of Cr₂O₃ scales. Continous TiO₂ layer was not formed at the alloys surface after oxidation. XRD analysis on the oxide scales of Fe-20Cr-Ti alloys confirms that Cr₂O₃ and TiO₂ oxide formed on the alloys. Ti addition into the alloys increases the oxidation rates of alloys at the initial stages. Oxidation behavior of Fe-20Cr-0.5Ti and Fe-20Cr-1Ti alloys showed two regimes. The parabolic rate constant, k_p (in gr²/cm⁴s) were 1.57 x 10^-13 and 3.08 x 10^-13 respectively for initial stage of oxidation then changed to-9 x 10^-15 and-3 x 10^-14 respectively for the remainder of the test. ASR measurement shows that the presence of Ti in the alloys decreases the electrical resistance up to 60%. Ti addition into Fe-Cr alloys affect the oxide growth rate and increase the conductivity of Cr₂O₃ scales.

• Periodical: Applied Mechanics and Materials (Volume 660)
• Pages: 249-253
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.660.249
• Online since: October 2014
• Authors: Zaka Ruhma, Asep Ridwan Setiawan*, Aditianto Ramelan, Rochim Suratman
• Keywords: Conductivity, Ferritic Stainless Steel, Interconnect, Oxidation, SOFC

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