Chloridation-oxidation of Fe-Cr and Ni-Cr alloys at 800 C

Book · Tue Oct 01 04:00:00 EDT 1996

OSTI ID:376070

Zheng, X; Rapp, R A ^[1]

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1. Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

The chloridation-oxidation behavior of Fe-Cr (0--25wt%Cr) and Ni-Cr (0--20wt%Cr) alloys was studied at 800 C in three different H{sub 2}-HCl-H{sub 2}O(v) environments. In a low HCl and low H{sub 2}O(v) environment, where Cr{sub 2}O{sub 3} is thermodynamically stable, the corrosion resistance of the Fe-Cr alloys increased with increasing Cr content in the alloys. In a high HCl and high H{sub 2}O(v) environment, where FeCr{sub 2}O{sub 4} is stable and CrCl{sub 2} is metastable, the corrosion resistance of the Fe-Cr alloys depended similarly on the Cr content. Low-Cr Fe-Cr alloys exhibited large weight losses, while Fe-Cr alloys with higher than 19wt%Cr showed good corrosion resistance. In an environment of high HCl in the absence of H{sub 2}O(v), the evaporative corrosion rate was fast and limited by gas phase diffusion, and independent of the Cr content in the Fe-Cr alloys. Ni and Ni-Cr alloys generally showed good corrosion resistance in the environments of high H{sub 2}O(v) because of the low NiCl{sub 2} vapor pressure and formation of a protective Cr{sub 2}O{sub 3} scale. However, in the environment of high HCl in the absence of H{sub 2}O(v), selective evaporation of CrCl{sub 2} occurs, which results in Cr depletion and even networks of voids for a high-Cr Ni-Cr alloy.

• OSTI ID: 376070
• Report Number(s): CONF-960389--
• Country of Publication: United States
• Language: English

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