Electrochemical Measurements for Assessing Corrosion of Metal Alloys in Molten LiF-NaF-KF and MgCl2-NaCl-KCl

A method of ranking the rate of corrosion of metals in molten fluoride or chloride salts is proposed based on a zero-resistance ammeter (ZRA). The metal of interest for the corrosion study is shorted to a relatively noble metal counter electrode. Stainless steel 316 was tested in FLiNaK (LiF-NaF-KF). Haynes 230, stainless steel 316L, and Hastelloy C-22 were tested in MgCl2-NaCl-KCl. The ZRA oxidation current from SS-316L was reduced by 89% in FLiNaK after the addition of Li metal, which is known to reduce the redox potential. Post-test examination of metal surfaces and salt samples were also consistent with the relative ZRA current response in fluoride salt. Consistency was also observed between the relative ZRA response for the different metal alloys in the chloride salt and post-test analysis of metal and salt samples.

Automated summary

This study introduces a method for ranking the rate of corrosion of metals in molten fluoride or chloride salts based on ZRA. The experiments showed that adding Li metal in fluoride salt significantly reduced the oxidation current of SS-316L, while consistency was observed between the ZRA response of different metal alloys and post-test analysis in chloride salt.