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

Bongiorno, Valeria; Spotorno, Roberto; Paravidino, Daniele; Piccardo, Paolo

doi:10.3390/met11030405

Cited by 13 publications

(10 citation statements)

References 82 publications

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“…The external layer lowers the risk of chromium evaporation, even though the usage of protective coatings is mandatory (such as the one based on Co and Mn used in the present case) to fight against the chromium poisoning [29,30]. Other stainless-steel compositions suitable for the usage as interconnects [31][32][33] are commercially available, but none can work without a coating. In this paper, the selection of the steel was made by the company according to their best-practice principles.…”

Section: Resultsmentioning

confidence: 99%

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

2022

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An in-depth investigation was performed on a metallic interconnect extracted from an SOFC stack operated for 40,000 h. The characterization was performed on the surface and the cross-section, paying attention to the evolution of the materials due to the interaction with the dual atmosphere of the stack under operating parameters. The interaction between materials (i.e., metal substrate, coatings and atmospheres) and stack components (i.e., current collectors and MIC) generated several modifications that affected the surface and, in some cases, the bulk of the interconnect. The careful metallographic preparation allowed for the performance of an intensive microscopical characterization of the cross-sections all along the interconnect profile, from the inlet to the outlet of the fuel stream. The formation of thermal grown oxides on both sides and their evolution were studied and described. The interconnect, after 40,000 h, was still suitable for operation, but the few bulk changes due to the diffusion of Ni and the TGO that formed at the fuel side suggest the introduction of fuel side coatings to increase the life expectations of the whole stack.

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Section: Resultsmentioning

confidence: 99%

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

2022

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“…(with f Z and M Z the atomic fraction and the atomic weight of element Z, respectively), ρ the density in g/cm 3 , and N A Avogadro's number (mol −1 ). The depth profiles are based on the recoil spectra except for Ti, for which also the profile based on the Cl +7 backscattering spectrum (marked as Ti (RBS)) is displayed in order to increase the information depth for this element.…”

Section: Resultsmentioning

confidence: 99%

“…The original AlTiN layer composition is well preserved underneath these oxides although some interdiffusion of oxygen could be detected. Assuming a density ρ = 3.95 g/ cm 3 (typical value for Al 2 O 3 ), the formation of an oxide scale of ~ 120 nm after annealing at 800 °C could be derived from Eq. (1).…”

Section: Resultsmentioning

confidence: 99%

“…Thin films and coatings are currently being applied as emergent materials in a wide range of high temperature applications such as thermal barrier coatings for gas-turbine engines [1], thin films gas sensors [2], energy conversion materials [3], or solar selective coatings for solar thermal energy plant receivers [4,5]. These materials have to withstand aggressive environments characterized by high temperature, large temperature gradients, cyclic stresses, or the presence of oxidizing and corroding atmosphere [6].…”

Section: Introductionmentioning

confidence: 99%

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Comprehensive microstructural and optical characterization of the thermal stability of aluminum-titanium oxynitride thin films after high temperature annealing in air

et al. 2021

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The thermal stability of two AlyTi1-y(OxN1-x) layers prepared by cathodic vacuum arc deposition with different oxygen content was studied after high temperature annealing of the samples in air. These layers were designed to be part of solar-selective coating (SSC) stacks. Compositional and microstructural characterization of the thin films was performed before and after the thermal treatment by elastic recoil detection (ERD), transmission electron microscopy, and Raman spectroscopy. AlyTi1-yN sample was stable after 2 h of annealing at 450 °C. Initial stages of the formation of a surface oxide layer after annealing at 650 °C were observed both by ERD and Raman analysis. Contrarily, no changes were found after 2 h annealing treatment either at 450 and 650 °C in the composition and microstructure of AlyTi1-y(OxN1-x) sample. In both samples, the formation of a surface anatase TiO2 film was reported after 2 h annealing at 800 °C. These compositional and microstructural changes were correlated with the optical properties determined by spectroscopic ellipsometry. A transition from metallic to dielectric behavior with increasing annealing temperature was observed. These results complete the durability studies on the designed SSC based on AlyTi1-y(OxN1-x) materials, confirming that these stacks withstand breakdown at 600 °C in air.

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“…Ferritic Stainless Steels (FSSs) are the most promising interconnect materials due to their high-temperature oxidation resistance. Such material family is characterised by the ability to form a superficial layer of passivating chromium oxide that protects alloys [17]. However, the high involved temperatures as well as the oxidanthumid cathodic environment lead to the oxide scale thickening [18].…”

Section: Of 19mentioning

confidence: 99%

Test and Modelling of Solid Oxide Fuel Cell Durability: A Focus on Interconnect Role on Global Degradation

et al. 2022

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High-temperature fuel cells are a promising technology due to their high energy efficiency and low environmental impacts compared to conventional engines. Nevertheless, they have a limited lifetime which reduces the use to a few application fields. Among them, Solid Oxide Fuel Cells (SOFCs) have had a recent development at the industrial level in two possible configurations: anode- and electrolyte-supported design. Considering the impossibility to experimentally distinguish the effects of every degradation mechanism on global cell performance, each layer should be tested singularly through ex situ tests and then assembled into a virgin cell to evaluate its role on the whole system by in situ tests. However, this procedure results as quite complex, and some further microstructural changes could occur during cell sintering. In order to overcome these constraints, the proposed approach paired ex situ experimental observations on a single element with modelling results on global SOFC. As a case study, CoMnO/Crofer22 APU and CuMnO/AISI 441 interconnect samples were tested, measuring their resistance variation for some hundreds of hours, followed by a detailed post-mortem microstructural analysis. Based on a previously validated local model, SIMFC (SIMulation of Fuel Cells), the durability of commercial anode- and electrolyte-supported cells was simulated, adding specific degradation functions only for the interconnects in order to highlight their influence on SOFC performance.

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

Cited by 13 publications

References 82 publications

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

Investigation of a Metallic Interconnect Extracted from an SOFC Stack after 40,000 h of Operation

Comprehensive microstructural and optical characterization of the thermal stability of aluminum-titanium oxynitride thin films after high temperature annealing in air

Test and Modelling of Solid Oxide Fuel Cell Durability: A Focus on Interconnect Role on Global Degradation

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