分析電気化学における洞察 オープンアクセス

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Corrosion Monitoring by Electrochemical Impedance Spectroscopy Test of Low-Cr Alloy Steel T22 and High-Ni Alloy HR224 in Nitrate Molten Salt

Angel G Fernandez* and Abdiel Mallco

High temperature corrosion is one of the most important issues for materials selection, structure design and service life prediction of engineering parts that are exposed to high-temperature environments. The prevention of high temperature corrosive attacks on materials play a critical role in aspects such as reliability, quality, safety and profitability of any industrial sector associated with high temperature process and in the study case, solar energy storage market, using inorganic molten salts. This paper proposes a corrosion monitoring technique based on Electrochemical Impedance Spectroscopy (EIS) and propose the corrosion mechanism that occurs during the test. Tests were carried out in conventional solar salt (60% NaNO3+40% KNO3) at 390°C in contact with a low Cr alloy steel (T22) and in a Ni base alloy (HR224). The corrosion monitoring technique performed in situ in contact with the salts showed a lower corrosion rate (0.0065 mm/year) in the Ni alloy compared with the low Cr alloy T22 (0.022 mm/year). Regarding the corrosion mechanism both steel formed a protective layer in the steel surface at the beginning of the corrosion test.