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Corrosion behavior of UCX, KHR35, and KHR45 alloys in molten nitrates
Author(s) -
BritoHernandez Daniel,
LopezSesenes Roy,
Haro Sergio,
PorcayoCalderon Jesus,
GonzalezRodriguez Jose G.
Publication year - 2020
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.202011579
Subject(s) - dielectric spectroscopy , materials science , corrosion , alloy , molten salt , metallurgy , polarization (electrochemistry) , electrochemistry , diffraction , analytical chemistry (journal) , chemistry , electrode , physics , chromatography , optics
The corrosion behavior of three high‐Ni, high‐Cr alloys, that is, UCX, KHR35, and KHR45 alloys, in a mixture of 60% NaNO 3 –40% KNO 3 at 600°C has been evaluated by using weight loss tests, potentiodynamic polarization curves, and electrochemical impedance spectroscopy measurements. Cr contents ranged between 23.25 and 43.2 wt.%, whereas Ni ranged between 36.6 and 50.3 wt.%. For comparison, the same studies were performed on 304‐type stainless steel (304SS). Tests were complemented with detailed scanning electronic microscope and X‐ray diffraction studies. Results showed that that the three high‐Ni, high‐Cr alloys had lower weight loss than that for 304SS. Polarization tests indicated the formation of a passive layer in all cases. Electrochemical impedance spectroscopy data have shown that the corrosion mechanism for all the alloys was charge transfer from the alloy to the molten salt. Finally, X‐ray patterns showed the presence of Cr 2 O 3 in all tested alloys, which is responsible for the observed passive behavior and their corrosion resistance.