Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells

Jun Woo Kim; Kiho Bae; Hyun Joong Kim; Ji won Son; Namkeun Kim; Stefan Stenfelt; Fritz B. Prinz; Joon Hyung Shim

doi:10.1016/j.jallcom.2018.04.176

Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells

Jun Woo Kim
, Kiho Bae
, Hyun Joong Kim
, Ji won Son
, Namkeun Kim
, Stefan Stenfelt
, Fritz B. Prinz
, Joon Hyung Shim^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

32 Citations (Scopus)

Abstract

Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500–900 °C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol% YSZ appears primarily at 800 °C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation.

Original language	English
Pages (from-to)	148-154
Number of pages	7
Journal	Journal of Alloys and Compounds
Volume	752
DOIs	https://doi.org/10.1016/j.jallcom.2018.04.176
Publication status	Published - 2018 Jul 5

Bibliographical note

Funding Information:
This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0 ). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377 ). Appendix A

Funding Information:
This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377).

Publisher Copyright:
© 2018 Elsevier B.V.

Keywords

3D reconstruction
Finite element analysis
Focused ion beam-scanning electron microscope
NiO-YSZ anode functional layer
Thermal stress

ASJC Scopus subject areas

Mechanics of Materials
Mechanical Engineering
Metals and Alloys
Materials Chemistry

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10.1016/j.jallcom.2018.04.176

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@article{6e6ecf7202204984beec4103d4645efd,

title = "Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells",

abstract = "Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500–900 °C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol\% YSZ appears primarily at 800 °C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation.",

keywords = "3D reconstruction, Finite element analysis, Focused ion beam-scanning electron microscope, NiO-YSZ anode functional layer, Thermal stress",

author = "Kim, \{Jun Woo\} and Kiho Bae and Kim, \{Hyun Joong\} and Son, \{Ji won\} and Namkeun Kim and Stefan Stenfelt and Prinz, \{Fritz B.\} and Shim, \{Joon Hyung\}",

note = "Funding Information: This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0 ). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377 ). Appendix A Funding Information: This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377). Publisher Copyright: {\textcopyright} 2018 Elsevier B.V.",

year = "2018",

month = jul,

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doi = "10.1016/j.jallcom.2018.04.176",

language = "English",

volume = "752",

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journal = "Journal of Alloys and Compounds",

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T1 - Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells

AU - Kim, Jun Woo

AU - Bae, Kiho

AU - Kim, Hyun Joong

AU - Son, Ji won

AU - Kim, Namkeun

AU - Stenfelt, Stefan

AU - Prinz, Fritz B.

AU - Shim, Joon Hyung

N1 - Funding Information: This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0 ). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377 ). Appendix A Funding Information: This research was supported by the Korean Ministry of Environment (MOE) as a “Public Technology Program based on Environmental Policy” (No. E416-00070-0604-0). This work was also supported by the National Research Foundation of Korea grant funded by the Korean government (MSIP) (No. NRF-2016R1D1A1B03932377). Publisher Copyright: © 2018 Elsevier B.V.

PY - 2018/7/5

Y1 - 2018/7/5

N2 - Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500–900 °C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol% YSZ appears primarily at 800 °C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation.

AB - Nickel-yttria-stabilized zirconia (Ni-YSZ) cermet is widely used as an anode material in solid oxide fuel cells (SOFCs); however, Ni re-oxidation causes critical problems due to volume expansion, which causes high thermal stress. We fabricated a Ni-YSZ anode functional layer (AFL), which is an essential component in high-performance SOFCs, and re-oxidized it to investigate the related three-dimensional (3D) microstructural and thermo-mechanical effects. A 3D model of the re-oxidized AFL was generated using focused ion beam-scanning electron microscope (FIB-SEM) tomography. Re-oxidation of the Ni phase caused significant volumetric expansion, which was confirmed via image analysis and calculation of the volume fraction, connectivity, and two-phase boundary density. Finite element analysis (FEA) with simulated heating to 500–900 °C confirmed that the thermal stress in re-oxidized Ni-YSZ is concentrated at the boundaries between YSZ and re-oxidized NiO (nickel oxide). NiO is subjected to more stress than YSZ. Stress exceeding the fracture stress of 8 mol% YSZ appears primarily at 800 °C or higher. The stress is also more severe near the electrolyte-anode boundary than in the Ni-YSZ cermet and the YSZ regions. This may be responsible for the electrolyte membrane delamination and fracture that are observed during high-temperature operation.

KW - 3D reconstruction

KW - Finite element analysis

KW - Focused ion beam-scanning electron microscope

KW - NiO-YSZ anode functional layer

KW - Thermal stress

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DO - 10.1016/j.jallcom.2018.04.176

M3 - Article

AN - SCOPUS:85045713450

SN - 0925-8388

VL - 752

SP - 148

EP - 154

JO - Journal of Alloys and Compounds

JF - Journal of Alloys and Compounds

ER -

Three-dimensional thermal stress analysis of the re-oxidized Ni-YSZ anode functional layer in solid oxide fuel cells

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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