Formation of spinel reaction layers in manganese cobaltite – coated Crofer22 APU for solid oxide fuel cell interconnects

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

doi:10.1016/j.jpowsour.2012.07.091

Cited by 88 publications

(46 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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: 61%

“…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%

“…An unusual variation in the composition of the spinel RL was observed wherein the Cr content decreased during the initial stages of oxidation and then increased again for longer exposures. 11 It was proposed that this effect might arise due to outward diffusion of Cr from the Crofer substrate into the metallic Co phase during the reduction stage of the reactive sintering process. To test this hypothesis, we prepared a sample for which the MCO slurry coating on Crofer has been reduced but not reoxidised.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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: Introductionmentioning

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

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

show abstract

“…3 µm thick Cr 2 O 3 + (Mn,Cr) 3 O 4 scale forms at the coating/alloy interface[30]. After a re-oxidation heat treatment, a reaction layer comprising Mn, Cr, Co and Fe is detected between the oxide scale and the re-oxidized coating[51]. The oxide scale now consists of primarily Cr 2 O 3 .…”

mentioning

confidence: 99%

Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

Talic¹,

Falk-Windisch

Venkatachalam³

et al. 2017

Journal of Power Sources

View full text Add to dashboard Cite

Manganese cobalt spinel oxides are promising materials for protective coatings for solid oxide fuel cell (SOFC) interconnects. To achieve high density such coatings are often sintered in a two-step procedure, involving heat treatment first in reducing and then in oxidizing atmospheres. Sintering the coating inside the SOFC stack during heating would reduce production costs, but may 2 result in a lower coating density. The importance of coating density is here assessed by characterization of the oxidation kinetics and Cr evaporation of Crofer 22 APU with MnCo 1.7 Fe 0.3 O 4 spinel coatings of different density. The coating density is shown to have minor influence on the longterm oxidation behavior in air at 800 °C, evaluated over 5000 h. Sintering the spinel coating in air at 900 °C, equivalent to an in-situ heat treatment, leads to an 88 % reduction of the Cr evaporation rate of Crofer 22 APU in air-3% H 2 O at 800 °C. The air sintered spinel coating is initially highly porous, however, densifies with time in interaction with the alloy. A two-step reduction and re-oxidation heat treatment results in a denser coating, which reduces Cr evaporation by 97 %.

show abstract

“…For the deposition of protective‐conducting coatings, many different methods have been developed. Starting from slurry deposition, electrophoretic deposition, to physical vapor deposition and electrodeposition . Different deposition methods result in different microstructures and often require an additional processing step for debinding or sintering.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of electrodeposited Mn‐Co protective coatings on Crofer 22 APU steel

Molin

2017

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

Interconnects used in Solid Oxide Cells stacks require protective coatings to lower their parabolic rate constant and block chromium evaporation (on the air side). In this work four different protective coatings on steel are evaluated for their high temperature corrosion resistance and electrical conductivity. A commercial electroplating process was used for the preparation of coatings with different Mn/Co ratios on Crofer 22 APU steel. Oxidation of samples was performed in air at 800°C for 1000 hours. Postmortem analysis of the coated samples was performed by scanning electron microscopy and x-ray diffractomettry. Based on the results, influence of the Co/Mn ratio on the resulting corrosion properties are discussed.Parabolic rate constant of the coated samples is the lowest for the MnCo sample, whereas electrical resistance is the lowest for the Co sample, which has a corrosion rate similar to the not-coated alloys. K E Y W O R D S coatings, microstructure, solid oxide fuel cell, spinels

show abstract

Formation of spinel reaction layers in manganese cobaltite – coated Crofer22 APU for solid oxide fuel cell interconnects

Cited by 88 publications

References 24 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

Effect of coating density on oxidation resistance and Cr vaporization from solid oxide fuel cell interconnects

Evaluation of electrodeposited Mn‐Co protective coatings on Crofer 22 APU steel

Contact Info

Product

Resources

About