Electrochemical study of the redox buffering behavior of Sm(III)/Sm(II) in NaF-BeF2 melt

Extensive research has investigated the redox behavior of Sm(III)/Sm(II) in the NaF-BeF2 melt for corrosion control. Results shows a quasi-reversible process with diffusion-controlled mass transfer. The concentration ratio of the couple is stable and controllable. The corrosion inhibition performance of the Sm(III)/Sm(II) couple is evaluated for 316H stainless steel and GH3535 superalloy, showing effective control when the concentration ratio remains below 69.0. Adding SmF3 at a concentration higher than 1.15wt% resulted in negligible galvanic corrosion. Overall, the stable and easily controlled Sm(III)/Sm(II) couple is an excellent corrosion inhibitor for both normal and galvanic corrosion in the NaF-BeF2 melt.