Electrochemical Study on the Kinetic Properties of Fe2+/Fe, Ni2+/Ni, Cr2+/Cr and Cr3+/Cr2+ in Molten MgCl2-KCl-NaCl Salts

The fundamental kinetic parameters of corrosion product ions (Fe, Ni and Cr ions) are of significant importance to understand the corrosion mechanisms of the structural materials in the molten salts. In the present study, the fundamental data of Fe2+, Ni2+, Cr2+ and Cr3+ (diffusion coefficient D, exchange current density i(0), charge transfer coefficient alpha, limiting current density i(L) and standard rate constant k(0)) were measured at different concentrations (1.53 x 10(-6)-7.48 x 10(-4) mol cm(-3)) and temperatures (600 degrees C-800 degrees C). The values of D are independent of concentrations and follow Arrhenius law with temperature, which descend in the order ofD(Cr2+) > DFe2+ > DCr3+ > DNi2+, with values ranging from 0.94 x 10(-5) to 3.31 x 10(-5) cm(2) s(-1). Both i(0) and k(0) depend on the temperatures, which also follow Arrhenius law. The values of the estimated k(0) descend in the order of k(Cr2+)(0) > k(Fe2+)(0) > k(Ni2+)(0) > k(Cr3+)(0) which range from 1.88 x 10(-5) to 9.06 x 10(-4) cm s(-1). (c) 2021 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.

Automated summary

The fundamental kinetic parameters of Fe2+, Ni2+, Cr2+ and Cr3+ in molten salts, including diffusion coefficient, exchange current density, charge transfer coefficient, limiting current density, and standard rate constant, were measured at different concentrations and temperatures. Results show the importance of these parameters in understanding the corrosion mechanisms of structural materials in molten salts.