11–23% Cr steels for solid oxide fuel cell interconnect applications at 800 °C – How the coating determines oxidation kinetics

Reddy, Mareddy Jayanth; Chausson, T.E.; Svensson, Jan‐Erik; Froitzheim, Jan

doi:10.1016/j.ijhydene.2022.11.326

Cited by 30 publications

(14 citation statements)

References 77 publications

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“…This will be compared with a rather stack-like contacting with different MICs and the application of a cerium cobalt (CeCo) protective coating (6,28,29) by IV-characteristics and electrochemical impedance measurements (EIS). Based on a method by Kornely et al (30) the contact loss is experimentally and individually determined at fuel and air side by targeted measurements of potential probes.…”

Section: Introductionmentioning

confidence: 99%

From Ideal to Stack-like Contacting of an SOC

et al. 2023

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The performance of an SOC depends on the testing environment. Regarding single cell tests with ideal contacting (gold and nickel meshes) and inert flow fields (Al2O3), the performance is limited by the intrinsic losses in the cell as contact losses and any poisoning effects are minimized. In an SOC-stack exhibiting metallic interconnectors, the performance is furthermore affected by contact resistances and limitations in gas supply. In this contribution single cell testing is extended to a stack-like contacting applying three different metallic interconnectors (Crofer 22 APU, ASTM 441 and UNS S44330) with and without a cerium-cobalt PVD-coating. Cell performance and losses are analyzed by IV-characteristics, impedance spectroscopy and DRT analysis. For all uncoated interconnectors, significant performance losses due to increased contact losses and air electrode polarization were observed. With the CeCo-coating losses could be drastically reduced leading to a cell performance close to the ideal case for all three steel grades.

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Section: Introductionmentioning

confidence: 99%

From Ideal to Stack-like Contacting of an SOC

et al. 2023

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“…Ce/Co coatings have been highly effective and stable for over 35000 hours (13). In our previous paper (10), we have shown that the various steels, such as AISI 441, AISI 444, AISI 409, AISI 430 and Crofer 22 APU, showed dissimilar oxidation kinetics when uncoated. However, when coated with Ce/Co, they showed similar oxidation kinetics at 800°C.…”

Section: Introductionmentioning

confidence: 93%

“…The metallic Co coating transforms to Co3O4 upon oxidation, which further transforms to MCO by Mn diffusion from the steel. Co coatings have been shown to reduce the Cr evaporation of FSS by 60 times at 800°C (10).…”

Section: Introductionmentioning

confidence: 99%

Strategies to Improve the Effectiveness of the Thin Film Coated Interconnects

Reddy,

Almyren,

Svensson

et al. 2023

ECS Trans.

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Ferritic stainless steels are used as interconnect materials in solid oxide cells (SOFC/SOEC). To enhance their performance and extend the lifespan of SOC’s, FSS interconnects are typically coated with protective coatings. MCO coatings deposited through physical vapor deposition have been extensively studied for this purpose. However, most studies have been conducted on in isothermal conditions which do not reflect the conditions experienced in stacks. Stacks are typically conditioned at high temperatures, usually 100-250°C above the operating temperatures, to ensure gas tightness. Thus, it is important to understand the influence of pre-oxidation on behaviour of the interconnect. The influence of pre-oxidation on Ce/Co-coated Crofer 22 APU and AISI 441 is studied at 850°C in air. The samples are characterised using scanning electron microscopy. The oxidation behaviour of Ce/Co-coated Crofer 22 APU improved significantly upon pre-oxidation whereas only minimal effect was observed for Ce/Co-coated AISI 441.

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“…[15][16][17] Numerous further steel grades such as AISI 441, 444, 430, 409 and others were investigated in literature. [18][19][20][21][22][23] In order to minimize Cr-evaporation and corrosion from the MIC, protective coatings need to be applied especially on the air side. 14,24,25 This decreases chromium poisoning of the air electrode and the contact resistance between electrode and MIC.…”

mentioning

confidence: 99%

“…In a previous study by Reddy et al 18 different steel grades (AISI 441, 444, 430, 409) were investigated in the uncoated and coated (CeCo) state by time-resolved mass gains, chromium evaporation (denuder technique 47 ) and measurements of the area-specific resistance (ASR). A different oxidation rate as well as Cr-evaporation was found between the uncoated steels.…”

mentioning

confidence: 99%

Impact of CeCo-Coated Metallic Interconnectors on SOCs Towards Performance, Cr-Oxide-Scale, and Cr-Evaporation

Grosselindemann,

Reddy,

Störmer

et al. 2024

J. Electrochem. Soc.

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Performance of a solid oxide cell (SOC) depends on the operating environment. Regarding single cell tests with ideal contacting (gold, platinum, nickel meshes) and inert flow fields (Al2O3), performance is limited by intrinsic losses in the cell. Contact losses and poisoning effects are minimized. In a SOC-stack with metallic interconnectors, performance is affected by contact resistances, chromium (Cr) evaporation, and limitations in gas supply. Here, 1 cm² single cells were tested with a stack-like contact applying metallic flow fields made from three different steel grades (Crofer 22 APU, AISI 441, UNS S44330) with and without a cerium-cobalt PVD-coating. Cell performance and losses were analyzed by IV-characteristics, impedance spectroscopy, and DRT analysis. For all uncoated interconnectors, significant performance losses due to increased contact losses and air electrode polarization were observed, which is attributed to Cr-oxide scale formation on the metallic interconnectors and Cr-poisoning of the air electrode as revealed by scanning electron microscopy-energy-dispersive X-ray spectroscopy. A CeCo-coating leads to similar oxide scales irrespective of the substrate material. Moreover, with the coating the electrochemical performance drastically improved due to decreased contact losses and an effective blocking of Cr-evaporation leading to a cell performance close to the ideal case for all three steel grades

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11–23% Cr steels for solid oxide fuel cell interconnect applications at 800 °C – How the coating determines oxidation kinetics

Cited by 30 publications

References 77 publications

From Ideal to Stack-like Contacting of an SOC

From Ideal to Stack-like Contacting of an SOC

Strategies to Improve the Effectiveness of the Thin Film Coated Interconnects

Impact of CeCo-Coated Metallic Interconnectors on SOCs Towards Performance, Cr-Oxide-Scale, and Cr-Evaporation

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