Mitigation corrosion in molten chloride salt NaCl-MgCl₂ through oxoacidity and redox control
Abstract
This study focuses on mitigating corrosion in the molten chloride salt NaCl-MgCl₂ by stabilizing the salt redox potential at ≃ -2 vs (Cl₂/Cl-)/V through the use of the SmCl₃/SmCl₂ redox couple, combined with oxoacidity regulation via AlCl₃. The reversible, thermally stable and soluble/soluble SmCl₃/SmCl₂ system effectively imposes a stable potential of -2 V at 700 °C. Aluminum plays a dual role: it reduces SmCl₃ to SmCl₂ and regulates oxoacidity, preventing samarium precipitation and ensuring stability of the x(SmCl₃)/x(SmCl₂) (ratio 1:5), and consequently the redox potential. Corrosion tests were conducted on Ni-based (Alloy 625) and Fe-based (316 L stainless steel) alloys immersed in NaCl-MgCl₂ at 700 °C for 13 days. The salt chemistry was controlled by fixing both the oxoacidity and the redox potential. The results demonstrate the effectiveness of this approach by positioning metallic materials within their immunity domain. Alloy 625 exhibited no intergranular neither micrometric-scale corrosion, whereas 316 L stainless steel showed only a 1 µm corrosion layer. This is a significant improvement compared to the loss of 100 µm of material observed when the salt chemistry was not controlled. The redox potential remained stable at -1.96 vs (Cl₂/Cl-)/V, confirming the robustness of the redox potential and oxoacidity control approach<
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BibTeX
@article{carriere2026mitigation,
title = {{Mitigation corrosion in molten chloride salt NaCl-MgCl₂ through oxoacidity and redox control}},
author = {Charly Carrière and Marc Cabrières and Celine Cannes and Davide Rodrigues and Sylvie Delpech},
journal = {Electrochimica Acta},
year = {2026},
month = oct,
doi = {10.1016/j.electacta.2026.149260},
url = {https://hal.science/hal-05734317v1},
note = {CC BY-ND 4.0},
}
RIS
TY - JOUR
TI - Mitigation corrosion in molten chloride salt NaCl-MgCl₂ through oxoacidity and redox control
AU - Charly Carrière
AU - Marc Cabrières
AU - Celine Cannes
AU - Davide Rodrigues
AU - Sylvie Delpech
PY - 2026
DA - 2026/10/08
JO - Electrochimica Acta
DO - 10.1016/j.electacta.2026.149260
UR - https://hal.science/hal-05734317v1
AB - This study focuses on mitigating corrosion in the molten chloride salt NaCl-MgCl₂ by stabilizing the salt redox potential at ≃ -2 vs (Cl₂/Cl-)/V through the use of the SmCl₃/SmCl₂ redox couple, combined with oxoacidity regulation via AlCl₃. The reversible, thermally stable and soluble/soluble SmCl₃/SmCl₂ system effectively imposes a stable potential of -2 V at 700 °C. Aluminum plays a dual role: it reduces SmCl₃ to SmCl₂ and regulates oxoacidity, preventing samarium precipitation and ensuring stability of the x(SmCl₃)/x(SmCl₂) (ratio 1:5), and consequently the redox potential. Corrosion tests were conducted on Ni-based (Alloy 625) and Fe-based (316 L stainless steel) alloys immersed in NaCl-MgCl₂ at 700 °C for 13 days. The salt chemistry was controlled by fixing both the oxoacidity and the redox potential. The results demonstrate the effectiveness of this approach by positioning metallic materials within their immunity domain. Alloy 625 exhibited no intergranular neither micrometric-scale corrosion, whereas 316 L stainless steel showed only a 1 µm corrosion layer. This is a significant improvement compared to the loss of 100 µm of material observed when the salt chemistry was not controlled. The redox potential remained stable at -1.96 vs (Cl₂/Cl-)/V, confirming the robustness of the redox potential and oxoacidity control approach<
SN - 0013-4686
ER -