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Corrosion behaviour of Nimonic–75 and Ni–19.4 Cr–1.25 Al in NaCl and Na 2 SO 4
Author(s) -
Kameswari S.,
Misra R. D. K.
Publication year - 1987
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19870380104
Subject(s) - nimonic , corrosion , alloy , materials science , metallurgy , high temperature corrosion , volume fraction , recrystallization (geology) , superalloy , composite material , paleontology , biology
The corrosion behaviour of Nimonic‐75 and Ni‐Cr‐Al alloys has been investigated in NaCl and Na 2 SO 4 by employing the half‐immersion crucible test. Weight loss results obtained as a function of temperature (700–800°C) and concentration of NaCl in the mixture (1–30 wt%) show that the highest attack occurs in Na 2 SO 4 ‐3% NaCl mixture around 750°C, for Nimonic‐75 and 800°C for Ni‐Cr‐Al, resulting in blister formation for both the alloys. The results also show that the addition of Al to Ni‐Cr alloy drastically enhances corrosion. Pre‐heating the Ni‐Cr‐Al alloy to recrystallization temperature for 2 to 4 h fails to indicate any inhibiting effect on catastrophic corrosion. The results strongly suggest that it is not only the concentration of NaCl in the mixture and the temperature of the salt mixture but also the volume fraction of liquid which plays a predominant role in the enhancement of corrosion attack.