Corrosion phenomena of alloys and electrode materials in Molten Carbonate Fuel Cells

Biedenkopf, P.; Bischoff, Manfred; Wochner, T.

doi:10.1002/(sici)1521-4176(200005)51:5<287::aid-maco287>3.0.co;2-8

Cited by 37 publications

(20 citation statements)

References 9 publications

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“…On the contrary, outward iron cation transport may become the controlling diffusion process in deep carbonate melts, leading thus to more porous and soluble iron oxide films as a result of lowered degree of lithiation or formal iron oxidation state. [38][39][40][41] The influence of depth of immersion on the iron oxide precursor seems to be confirmed by the fact that a spinel iron oxide mostly composed of a partially-oxidized Li 5 Fe 5 O 8 phase has been observed only if the coating process is carried out under deep melt bath conditions. Formation of this phase during corrosion of metallic iron in deep carbonate melts has been already described by Biendenkopf et al, 42 at 650…”

Section: F856mentioning

confidence: 93%

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Masi

Frangini

Seta

et al. 2017

J. Electrochem. Soc.

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In this work, a novel iron chemical conversion coating process has been applied to deposit a composite Cu-LaFeO 3 perovskite coating layer on a commercial 18Cr ferritic stainless steel for application as Intermediate-Temperature Solid Oxide Fuel Cell (IT-SOFC) interconnect. The conversion process is carried out at 600 • C under a CO 2 gas atmosphere in a binary eutectic lithium-sodium molten carbonate bath containing lanthanum, magnesium and copper additions in form of their respective oxides. Multi-layer coatings are obtained, with a surface composite layer formed by a dense perovskite polycrystalline thick film with metallic copper particles encased in the perovskite grains grown on a Fe-rich spinel sublayer. Copper oxide additions significantly promote the formation of the LaFeO 3 perovskite layer, and the experimental results suggest that galvanic coupling phenomena between the alloy elements and copper take place during the coating formation process. Chemical stability and Cr diffusion barrier properties of the composite coating have been evaluated in air exposure experiments at 700 • C for 200 h. The perovskite phase shows high stability after the high temperature exposure, with no detectable sign of Cr diffusion in the layer. Details on functional properties of these composite conversion coatings for IT-SOFC applications will be reported in a subsequent study.

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Section: F856mentioning

confidence: 93%

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Masi

Frangini

Seta

et al. 2017

J. Electrochem. Soc.

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“…Thus, for instance, it could be thought that lithiation would induce sudden changes in the electrical properties of the oxide scale in a manner similar to what happens for passive films in water. However, the corrosion scale conductivity of stainless steels in carbonate melts decreases progressively with time and it is not substantially affected by lithiation of the corrosion scale [19,25], thus excluding this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate melts

Frangini

2006

Materials & Corrosion

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Potentiodynamic polarization measurements have been employed to evaluate the anodic behavior of a type 310S stainless steel in the eutectic Li/K molten carbonate. In general, the electrochemical tests yield useful information to predict the stability of the oxide films formed on the surface at the initial period of corrosion, although some precaution is required in the testing procedure as the reproducibility of results is seen to be adversely affected by the passage of large currents. Especially when the steel is in a passive state, erratic results are easily observed if the corrosion layer is being damaged by uncontrolled large currents. This is because the acid-base properties of the melt are susceptible to deep changes by applied currents in the milli-ampere range resulting in hysteresis phenomena in the polarization plot. Hysteresis is caused, on one hand, by acidic dissolution of the passive layer at high anodic currents and, on the other hand, by increased melt basicity due to oxide ion buildup at high cathodic currents. An optimized testing procedure is therefore suggested that minimizes these effects by imposing a 2 mA/cm 2 threshold current during polarization measurements. Moreover, the conditions for the applicability of the linear polarization technique to estimate kinetic parameters have been discussed in relationship with the corrosion mechanisms analysed by impedance spectra. It is concluded that the presence of diffusional impedance terms and formation of surface resistive films in molten carbonates may result in not reliable polarization resistance values obtained with the linear polarization.

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“…LiFeO 2 , in particular, has a very low conductivity (3x10 -3 S/cm) [5]. Formation of this compound on the surface of the membrane limits the transport of electrons to the CO 2 and O 2 gas mixture on the upstream side of the membrane.…”

Section: Membrane and (C) The Opposite Side Of Dual-phase Membranementioning

confidence: 99%

“…Therefore, the reaction becomes inhibited and formation CO 3 2-decreases. Consequently, the transport of CO 2 through the membrane is governed by a decrease in conductivity at high temperatures due to the formation of these lithium iron oxides [5,6].…”

Section: Membrane and (C) The Opposite Side Of Dual-phase Membranementioning

confidence: 99%

Dual Phase Membrane for High Temperature CO2 Separation

Lin¹

2007

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This project aimed at synthesis of a new inorganic dual-phase carbonate membrane for high temperature CO 2 separation. Metal-carbonate dual-phase membranes were prepared by the direct infiltration method and the synthesis conditions were optimized. Permeation tests for CO 2 and N 2 from 450-750°C showed very low permeances of those two gases through the dual-phase membrane, which was expected due to the lack of ionization of those two particular gases.Permeance of the CO 2 and O 2 mixture was much higher, indicating that the gases do form an ionic species, CO 3 2-, enhancing transport through the membrane. However, at temperatures in excess of 650°C, the permeance of CO 3 2-decreased rapidly, while predictions showed that permeance should have continued to increase with temperature.XRD data obtained from used membrane indicated that lithium iron oxides formed on the support surface. This lithium iron oxide layer has a very low conductivity, which drastically reduces the flow of electrons to the CO 2 /O 2 gas mixture; thus limiting the formation of the ionic species required for transport through the membrane. These results indicated that the use of stainless steel supports in a high temperature oxidative environment can lead to decreased performance of the membranes. This revelation created the need for an oxidation resistant support, which could be gained by the use of a ceramic-type membrane.Work was extended to synthesize a new inorganic dual-phase carbonate membrane for high temperature CO 2 separation. Helium permeance of the support before and after infiltration of molten carbonate are on the order of 10 -6 and 10 -10 moles/m 2 ⋅Pa⋅s respectively, indicating that the molten carbonate is able to sufficiently infiltrate the membrane. It was found that It was also observed that, because LSCF is a mixed conductor (conductor of both electrons and oxygen ions), the support was able to provide its own oxygen to facilitate separation of CO 2 .Without feeding O 2 , the LSCF dual phase membrane produced a maximum CO 2 flux of 0.246 ml/min·cm 2 at 900°C.4

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Corrosion phenomena of alloys and electrode materials in Molten Carbonate Fuel Cells

Cited by 37 publications

References 9 publications

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate melts

Dual Phase Membrane for High Temperature CO2 Separation

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Corrosion phenomena of alloys and electrode materials in Molten Carbonate Fuel Cells

Cited by 37 publications

References 9 publications

Composite Cu-LaFeO3Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Composite Cu-LaFeO3Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate melts

Dual Phase Membrane for High Temperature CO2 Separation

Contact Info

Product

Resources

About

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism

Composite Cu-LaFeO₃Conversion Coatings on a 18Cr Ferritic Stainless Steel for IT-SOFC Interconnects: An Investigation on Structure and Formation Mechanism