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Title: Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions

Abstract

The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1052527
Report Number(s):
PNNL-15304
AA2530000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Yang, Z Gary, Xia, Gordon, Stevenson, Jeffry W, and Singh, Prabhakar. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions. United States: N. p., 2005. Web. doi:10.2172/1052527.
Yang, Z Gary, Xia, Gordon, Stevenson, Jeffry W, & Singh, Prabhakar. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions. United States. doi:10.2172/1052527.
Yang, Z Gary, Xia, Gordon, Stevenson, Jeffry W, and Singh, Prabhakar. Fri . "Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions". United States. doi:10.2172/1052527. https://www.osti.gov/servlets/purl/1052527.
@article{osti_1052527,
title = {Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions},
author = {Yang, Z Gary and Xia, Gordon and Stevenson, Jeffry W and Singh, Prabhakar},
abstractNote = {The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.},
doi = {10.2172/1052527},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2005},
month = {7}
}

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