In Situ Monitoring of Molten Chloride Salt Chemistry and Corrosion Using a Microelectrode
November 1, 2024
The Science
In molten salt nuclear systems, corrosion and redox processes are often localized, but conventional electrochemical techniques measure only bulk behavior. Researchers developed a microelectrode approach to probe local electrochemical conditions in molten chloride salts. By combining electrochemical measurements with controlled positioning near surfaces, they observed spatial variations in redox activity and corrosion processes. These results show that local chemical environments can differ significantly from bulk conditions, linking microscale gradients to corrosion behavior.
The Impact
Accurate measurement of local chemistry is essential for understanding corrosion mechanisms in molten salts. This work provides a method to directly probe spatial variations in redox conditions. The approach enables improved interpretation of electrochemical data and supports development of diagnostic tools for molten salt systems.
Summary
This study introduced a glass-coated tungsten microelectrode for in situ electrochemical measurements in molten chloride salts.
The microelectrode enabled detection of redox reactions consistent with bulk measurements while providing enhanced spatial resolution. Corrections were applied to account for temperature-dependent current contributions from the glass coating.
Approach experiments revealed distinct behavior near different surfaces. Insulating surfaces restricted diffusion, while corroding alloy surfaces produced enhanced electrochemical signals due to local reactions and metal deposition.
Measurements of open-circuit potential showed strong local gradients near actively corroding regions, which diminished over time as diffusion homogenized the system.
Overall, the results demonstrate that molten salt electrochemistry is spatially heterogeneous, and that local measurements are essential for understanding corrosion processes.
Contact
Adrien Couet, University of Wisconsin–Madison, couet@wisc.edu
Funding
This work was supported by the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
Citation
Kim, C., and A. Couet. “In Situ Monitoring of Molten Chloride Salt Chemistry and Corrosion Using a Microelectrode.” Journal of the American Chemical Society 147, 19013–19025 (2025). https://doi.org/10.1021/jacs.5c03651
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