Corrosion Products Electrochemical Behaviour into Molten LiF-NaF: Investigation of Cr(II) System

Abstract

In this work, a detailed electrochemical study of the molten LiF-NaF-CrF2 system is provided on Ag electrode in the 750 °C–900 °C temperature range. The first part was dedicated to the electrochemical study, by cyclic and square wave voltammetries, allowing the determination of thermodynamic and physico-chemical data such as CrF2/Cr standard potential, diffusion coefficient, activity coefficient, transfer energy and nucleation overvoltage. The influence of Li2O addition on the electrochemical reduction pathway of dissolved CrF2 on a silver electrode was investigated. The results showed that an increase of Li2O activity in the solution causes CrF2 disproportionation into solid chromium oxide and metallic Cr.

Corrosion Electrochemistry of Chromium in Molten FLiNaK Salt at 600 °C

“…Prior to each experiment, a CV analysis was performed on a Pt electrode to identify possible impurities that can act as redox couples. 4,17,18,73 Apparatus.-Figure 1 shows the electrochemical cell developed to carry out electrochemical tests in molten salts. The experiment was performed in a N 2 -filled glove box.…”

“…These values support not only the thermodynamic phase stability maps (based on the n transferred for corrosion in each regime) but also imply that the total anodic reaction may involve some combination of half-cell reactions 10 and 12. While the literature has demonstrated that Cr(III) is more prevalent in molten fluorides, electrochemical studies of FLiNaK salts containing CrF 2 or CrF 3 species on a Pt wire have shown that 88-92% of Cr(II) can be oxidized to Cr(III) 16,17,29,[42][43][44][45] when a sufficient driving force is present, either controlled by applied potential or varying the concentration of oxidizers.…”

Potentiodynamic Polarization of Pure Metals and Alloys in Molten LiF-NaF-KF (FLiNaK) Using the K/K+ Dynamic Reference Electrode

“…25 A DRE produced with CV has been used to measure the voltammetric behavior of dissolved CrF 2 with respect to the Na/Na + redox couple in LiF-NaF. 28 In the authors' previous work, 26 a Be/Be 2+ DRE was created using a linear sweep voltammogram to form the Be/Be 2+ electrode. Its potential was determined with a subsequent open circuit potential (OCP) measurement.…”

Impact of NaCl impurity on corrosion of 316 L steel in molten nitrate salts for thermal energy storage: An electrochemical study

“…Furthermore, electrochemical techniques have been widely used in the study of molten salt corrosion, [ 16–22 ] and have been proved to be effective in understanding corrosion mechanisms, kinetics, and corrosion process. Fernández et al [ 23 ] investigated the positive effect of alumina‐forming on corrosion behavior of austenitic stainless steel using EIS method in molten nitrate salts.…”

“…Apart from this, the evaluation of the corrosion behavior of SS in molten nitrate salts containing high-content chloride impurity is limited. There are few investigations on the corrosion behavior of austenitic SS in molten nitrate salts containing chloride higher than 1 wt% by electrochemical measurements, especially electrochemical impedance spectroscopy (EIS), which is regarded as the effective and reliable technique for corrosion monitoring in CSP plants according to Encinas-Sánchez et al [16] Furthermore, electrochemical techniques have been widely used in the study of molten salt corrosion, [16][17][18][19][20][21][22] and have been proved to be effective in understanding corrosion mechanisms, kinetics, and corrosion process. Fernández et al [23] investigated the positive effect of alumina-forming on corrosion behavior of austenitic stainless steel using EIS method in molten nitrate salts.…”