Oxidation of potential SOFC interconnect materials, Crofer 22 APU and Avesta 353 MA, in dry and humid air studied<i>in situ</i>by X-ray diffraction

Garcia-Vargas, Maria Jose; Lelait, L.; Kolarik, V.; Fietzek, H.; Juez‐Lorenzo, M.

doi:10.1179/mht.2005.028

Cited by 7 publications

(5 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18,24,25 In these previous works, the metallic inclusions are attributed to stresses that arise from internal oxidation of titanium or the formation of MnCr 2 O 4 subscale pockets. Issartel et al accounted for these stresses on the basis of the Pilling-Bedworth ratio for these internal oxidation reactions.…”

Section: Discussionmentioning

confidence: 98%

“…The two interfacial layers observed (Cr 2 O 3 plus MnCr 2 O 4 ) are similar to those observed by us and by other authors in the scale on bare Crofer 22 APU oxidised in air at atmospheric pressure. 12,18 It has been established for bare Crofer, and other ferritic Fe-Cr-Mn stainless steels, that the chromia scale forms first. There is limited solubility of Mn 2 O 3 in Cr 2 O 3 (12-17 wt-%), and once this value is reached, MnCr 2 O 4 spinel nucleates on the surface and grows via a reaction between Mn 2 O 3 and Cr 2 O 3 .…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructural effects of the reduction step in reactive consolidation of manganese cobaltite coatings on Crofer 22 APU

Gambino

Magdefrau

Aindow

2015

Materials at High Temperatures

View full text Add to dashboard Cite

The microstructural effects of the reduction step in the reactive consolidation of slurry processed Mn 1?5 Co 1?5 O 4 coated Crofer 22 APU were studied using cross-sectional scanning and transmission electron microscopies. Alloy samples were coated with a Mn 1?5 Co 1?5 O 4 slurry and then reduced in moist H 2 based forming gas at 850uC for 4 h. The reduced coating contained particles of MnO with the NaCl structure and Co with the face centred cubic (FCC) structure. The interface exhibited a thin dense chromia layer with a thicker porous MnCr 2 O 4 overlayer with needle-like protrusions into the reduced coating. Evidence for inter-reactions during the concurrent coating reduction and substrate oxidation include Co rich metallic inclusions in the spinel layer and an enrichment of the spinel in Mn with distance from the chromia layer. The consequences of these observations for the complex microstructural variation during subsequent reoxidation and long term thermal exposure are discussed.

show abstract

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Microstructural effects of the reduction step in reactive consolidation of manganese cobaltite coatings on Crofer 22 APU

Gambino

Magdefrau

Aindow

2015

Materials at High Temperatures

View full text Add to dashboard Cite

show abstract

“…Presently, the majority of SOFC's utilises planar designs with high‐chromium ferritic steels such as Crofer 22 APU 1–5 or Crofer 22 H 6, 7 as the state of the art construction materials for interconnects. The oxidation behavior of this type of steels in SOFC relevant environments has extensively been studied by several authors 8–10. However, the behavior of the mentioned ferritic steels in a real planar SOFC stack may be substantially altered because the interconnect on the anode side is in direct contact with the Ni/YSZ cermet anode or, in most cases, with a nickel current collector 11.…”

Section: Introductionmentioning

confidence: 99%

Behavior of Metallic Components During 4,000 h Operation of an SOFC Stack with Carbon Containing Fuel Gas

et al. 2016

View full text Add to dashboard Cite

In the present study the behavior of the ferritic interconnect steel Crofer 22 APU and the nickel contacting material during exposure in anode gas of a solid oxide fuel cell (SOFC) stack was investigated. The stack had been operating for 4,000 h and was ten times subjected to thermal cycling within this time period. A temporary high carbon activity in the fuel gas combined with temperature changes resulted in local disintegration of the nickel mesh. Additionally, nickel diffusion from the nickel mesh into the steel resulted in the formation of an austenitic zone. Diffusion of steel constituents into the nickel mesh lead to the formation of Cr,Mn‐oxides in the latter. Presence of the nickel/steel contact allows transport of carbon from the gas into the steel, resulting in local internal carburization of the steel. In areas which were not in direct contact with the nickel mesh, the Crofer 22 APU interconnect formed a protective surface oxide scale and no indications for carbon uptake were found. Mechanisms for the experimentally observed effects, including the local disintegration of the nickel mesh, are presented.

show abstract

“…A continuous MnCr 2 O 4 layer between the chromia and the steel bulk was observed in literature for Crofer22APU when oxidised in dry conditions but not in humid conditions 36 . This would confirm that in SOFC mode, no water is present in the air stream, but it does not explain the observed difference between the channel and rib locations.…”

Section: Steel Bulkmentioning

confidence: 70%

“…Mn-rich chromia was also previously observed on manganese chromium steel 35 during the early stage of oxidation, as long as manganese is available in the bulk. A regular MnCr 2 O 4 spinel layer was observed on oxidised Crofer22APU already in 2005 36 . The following year, Mn-rich oxide was also observed between the chromia and the bulk during 6000h oxidation of Cr-Mn steels at 800°C 33 .…”

Section: Mco and Oxide Layers Microstructural Evolutionmentioning

confidence: 97%

TEM Characterization of Long Term Aged Interconnect Oxide Layers from Real Stack

et al. 2021

View full text Add to dashboard Cite

Interconnects from real SOFC stacks operated for 9000h and 20000h are characterized by means of SEM and TEM. This study focuses on the air side of the interconnect, which has been coated with manganese cobalt spinel oxide (MCO) doped with iron. Differences between the zones of air channel and interconnect rib are highlighted. Iron particles are found in the thermally grown oxide (TGO) exposed to the air channel. Manganese-rich crystals are observed close to the steel bulk for the rib contact zone, and in the bottom part of the TGO for the air channel zone. Cobalt is segregating at grain boundaries in the MCO after 20000h. More investigation is necessary to fully understand all mechanisms but the additional information gathered in the present study should help in better designing accelerated testing and modelling.

show abstract

Oxidation of potential SOFC interconnect materials, Crofer 22 APU and Avesta 353 MA, in dry and humid air studiedin situby X-ray diffraction

Cited by 7 publications

References 4 publications

Microstructural effects of the reduction step in reactive consolidation of manganese cobaltite coatings on Crofer 22 APU

Microstructural effects of the reduction step in reactive consolidation of manganese cobaltite coatings on Crofer 22 APU

Behavior of Metallic Components During 4,000 h Operation of an SOFC Stack with Carbon Containing Fuel Gas

TEM Characterization of Long Term Aged Interconnect Oxide Layers from Real Stack

Contact Info

Product

Resources

About