Mitigation corrosion in molten chloride salt NaCl-MgCl2 through oxoacidity and redox control
Year: 2026
Type: article
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 aluminum addition. 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 (316L 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 316L 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.
Source: Electrochimica Acta
Language: English
Subfield: Fluid Flow and Transfer Processes
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,790
OpenAlex ID: W7163417276