Effects of alloy heat treatment on oxidation kinetics and scale morphology for Crofer 22 APU

Magdefrau, Neal J.; Chen, Lei; Sun, Ellen Y.; Aindow, Mark

doi:10.1016/j.jpowsour.2013.03.181

Cited by 53 publications

(32 citation statements)

References 33 publications

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“…The microstructure of this reduced coating has been investigated using FIB and electron microscopy as in our previous studies. 11,12 It is shown that the interfacial microstructure in this sample is somewhat different from that anticipated, with thin chromia and spinel layers forming even during the reduction step. The consequences of these observations for the mechanisms of microstructural development in MCO coatings are discussed.…”

Section: Introductionmentioning

confidence: 63%

“…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%

“…11,12 It was found that the uncoated Crofer formed a two-layer chromiazMnCr 2 O 4 scale, whereas the MCO coated Crofer exhibited a (Mn,Co,Cr,Fe) 3 O 4 spinel RL between the coating and the chromia subscale on the Crofer substrate surface. The development of the RL was studied by comparing data from coated samples oxidised for different times at 800uC in air.…”

Section: Introductionmentioning

confidence: 99%

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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

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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.

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Section: Introductionmentioning

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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

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“…The grain boundary is highlighted by the presence of larger crystals oxide; this peculiarity is due to the fact that diffusion rate of ions along with the grain boundary is orders of magnitude faster than that of bulk diffusion being this a known short-circuit of diffusion [27,28].…”

Section: Subgroupsmentioning

confidence: 99%

K44M ferritic stainless steel as possible interconnect material for SOFC stack operating at 600 °C: Characterization of the oxidation behaviour at early working stages

Piccardo

Anelli

Bongiorno

et al. 2015

International Journal of Hydrogen Energy

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“…According to the literature, Cr 2 O 3 tends to form easily on the surface of the Crofer 22 APU due to the outward diffusion of Cr at the brazing temperatures. 25,26) In addition, MnCr 2 O 4 , CuCr 2 O 4 and FeCr 2 O 4 spinel oxides are then formed by a reaction between Cr 2 O 3 and Mn 3 O 4 , CuO and Fe 2 O 3 , respectively. Moreover, separation of oxide layers also takes place.…”

Section: Resultsmentioning

confidence: 99%

Effects of Reactive Air Brazing Parameters on the Interfacial Microstructure and Shear Strength of GDC–LSM/Crofer 22 APU Joints

Raju¹,

Kim²,

Seong³

et al. 2019

J. Korean Ceram. Soc

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In this paper, the joining characteristics of GDC-LSM ceramics with Crofer 22 APU metal alloys was investigated at different brazing temperatures and holding times by reactive air brazing. Brazing was performed using Ag-10 wt% CuO filler, at three different temperatures (1000, 1050, and 1100°C for 30 minutes) as well as for three different holding times (10, 30, and 60 minutes at 1050°C). The interfacial microstructures were examined by scanning electron microscopy and the joining strengths were assessed by measuring shear strengths at room temperature. The results show that with increasing brazing temperature and holding time, joint microstructure changed obviously and shear strength was decreased. Shear strength varied from a maximum of 100±6 MPa to a minimum of 18±5 MPa, depending on the brazing conditions. These changes were attributed to an increase in the thickness of the oxide layer at the filler/metal alloy interface.

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Effects of alloy heat treatment on oxidation kinetics and scale morphology for Crofer 22 APU

Cited by 53 publications

References 33 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

K44M ferritic stainless steel as possible interconnect material for SOFC stack operating at 600 °C: Characterization of the oxidation behaviour at early working stages

Effects of Reactive Air Brazing Parameters on the Interfacial Microstructure and Shear Strength of GDC–LSM/Crofer 22 APU Joints

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