scholarly journals Electrochemical behavior of lanthanum and yttrium ions in two molten chlorides with different oxoacidic properties: The eutectic LiCl-KCl and the equimolar mixture CaCl2-NaCl

2003 ◽  
Vol 39 (1-2) ◽  
pp. 109-135 ◽  
Author(s):  
Y. Castrillejo ◽  
M.R. Bermejo ◽  
A.M. Martínez ◽  
Arocas Díaz
Keyword(s):  
Electrochemical Behavior ◽  
Electrochemical Techniques ◽  
Three Dimensional ◽  
Earth Metal ◽  
Active Species ◽  
Chloride Ions ◽  
Equimolar Mixture ◽  
Transport Parameters ◽  
Tungsten Electrode ◽  
Simple Diffusion

The electrochemical behavior of LaCl3 and YCl3 was studied in two molten chloride mixtures with different oxoacidic properties, the eutectic LiCl-KCl and the equimolar CaCl2-NaCl melt at different temperatures. The stable oxidation states of both elements have been found to be (III) and (0) in both melts, and it was found that both La(III) and Y(III) cations were less solvated by the chloride ions in the calcium-based melt, which was explained by the stability of CaCl4 2- ions in that melt. Transient electrochemical techniques, such as cyclic voltammetry, chronopotentiometry and chronoamperometry were used in order to study the reaction mechanism and the transport parameters of electro active species at a tungsten electrode. The results showed that in the eutectic LiCl-KCl, the electro crystallization of lanthanum and yttrium seems to be the controlling electrochemical step while in CaCl2-NaCl this phenomenon has not been observed. That was explained in terms of the differences in the physicochemical properties of the systems, especially interfacial tensions. In the eutectic LiCl-KCl chronoamperometric studies indicated instantaneous and three dimensional nucleation and crystal growth of lanthanum and yttrium whatever the applied over potential of the rare earth metal is, whereas in the equimolar mixture CaCl2-NaCl, the corresponding electrochemical exchanges were found to be quasi-reversible, and the values of the kinetic parameters, K0 and ?,were obtained for both reactions. Mass transport towards the electrode is a simple diffusion process, and the diffusion coefficients have been calculated. The validity of the Arrhenius law was also verified by plotting the variation of the logarithm of the diffusion coefficient versus 1/T.

Comparison of Electrochemical Behavior of Cu-10Ni-10Zn Alloy and Cu in Aqueous Solutions

2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Waheed A. Badawy ◽  
Mohamed M. El-Rabiei ◽  
Hashem M. Nady ◽  
Mohammed A. Samy
Keyword(s):  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
Pure Copper ◽  
Open Circuit ◽  
Chloride Ions ◽  
Alloy Surface ◽  
Metallic Surface ◽  
Copper Dissolution ◽  
Basic Solutions

AbstractThe electrochemical behavior of Cu-10Ni-10Zn alloy and Cu was investigated in acidic, neutral and basic solutions. The effect of chloride ions in neutral solutions was also studied. Conventional electrochemical techniques and electrochemical impedance spectroscopy were used. The corrosion rate of these materials in acidic solutions is relatively high compared to that in neutral or basic solutions. The open-circuit potential of the alloy is nearly the same as that of pure copper in the different media, indicating that the processes which occur on the alloy surface are mainly governed by copper dissolution. In chloride solutions the rate of Cu corrosion is remarkably high. In the alloy, the copper dissolution was suppressed by the presence of nickel and zinc, due to the formation of complex oxide layers. The impedance data were fitted to equivalent circuit models that explain the different electrochemical processes occurring at the electrode/electrolyte interface. SEM and EDAX have shown that the alloy surface is enriched with Ni. In neutral solutions the chloride ions are penetrating the metallic surface.

The influence of various LiF concentrations on the cathodic electrochemical behavior at the tungsten electrode in Na3AlF6–Al2O3 molten salt

RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23915-23921
Author(s):  
Shaohu Tao ◽  
Yuezhong Di ◽  
Kejia Liu ◽  
Kun Zhao ◽  
Naixiang Feng ◽  
...  
Keyword(s):  
Molten Salt ◽  
Electrochemical Deposition ◽  
Electrochemical Behavior ◽  
Electrochemical Techniques ◽  
Deposition Process ◽  
Tungsten Electrode

The electrochemical deposition process of Al metal at the tungsten electrode in the melts of Na3AlF6–Al2O3 with various LiF concentrations was investigated at 1253 K by various electrochemical techniques.

scholarly journals Electrochemical Behavior and Electrodeposition of Sn Coating from Choline Chloride–Urea Deep Eutectic Solvents

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1154
Author(s):  
Xiaozhou Cao ◽  
Lulu Xu ◽  
Chao Wang ◽  
Siyi Li ◽  
Dong Wu ◽  
...  
Keyword(s):  
Electrochemical Behavior ◽  
Choline Chloride ◽  
Three Dimensional ◽  
Deep Eutectic Solvents ◽  
Xrd Analysis ◽  
Single Step ◽  
Tungsten Electrode ◽  
Diffusion Controlled ◽  
Nucleation Overpotential ◽  
And Diffusion

The electrochemical behavior and electrodeposition of Sn were investigated in choline chloride (ChCl)–urea deep eutectic solvents (DESs) containing SnCl2 by cyclic voltammetry (CV) and chronoamperometry techniques. The electrodeposition of Sn(II) was a quasi-reversible, single-step two-electron-transfer process. The average transfer coefficient and diffusion coefficient of 0.2 M Sn(II) in ChCl–urea at 323 K were 0.29 and 1.35 × 10−9 cm2∙s−1. The nucleation overpotential decreased with the increase in temperature and SnCl2 concentration. The results of the chronoamperometry indicated that the Sn deposition on tungsten electrode occurred by three-dimensional instantaneous nucleation and diffusion controlled growth using the Scharifker–Hills model. Scanning electron microscopy (SEM) showed that the morphology of the deposits is uniform, as a dense and compact film prepared by potentiostatic electrolysis on Cu substrate. X-ray diffraction (XRD) analysis revealed that the deposits were pure metallic Sn.

Studies on Cerium Electrochemistry in High Temperature Ionic Liquids

2018 ◽  
Vol 69 (1) ◽  
pp. 112-115
Author(s):  
Ana Maria Popescu ◽  
Virgil Constantin
Keyword(s):  
Molten Salts ◽  
Electrochemical Techniques ◽  
Active Species ◽  
Single Step ◽  
Cathodic Process ◽  
Molybdenum Electrode ◽  
Solute Interaction ◽  
Ohmic Drop ◽  
State Potential ◽  
Direct Discharge

The cathodic behavior of Ce3+ ions in LiF-NaF-BaF2, LiF-NaF-NaCl and NaCl-KCl molten salts at 730� C has been studied using different electrochemical techniques. The decomposition potential (Ed) and the cathodic overvoltage were determined by introducing NaCeF4 as electrochemical active species using steady-state potential-current curves recorded under galvanostatic conditions. The values of |Ed| were 1.85 V in LiF-NaF-BaF2, 2.114 V in LiF-NaF-NaCl and 2.538 V in NaCl-KCl, respectively. It was also found that the ohmic drop potential in melt is not dependent on NaCeF4 concentration and it rises as the current intensity increases. The Tafel slopes and other kinetic parameters were calculated on the assumption that the cathodic process consisted of direct discharge of Ce3+, with no solvent-solute interaction. In order to elucidate the mechanisn of cathodic process the cyclic voltammetry technique was finally used. From the evolution of the voltammograms we conclude that the electrochemical reduction of Ce3+ ion is actually a reversible process on the molybdenum electrode and cathodic reduction of Ce3+ takes place in one single step involving three electron exchange. Our study adds to the accumulating data and confirms available results of electrodeposition of metalic cerium from molten salts using NaCeF4 as solute.

Effects of Stress and Plastic Deformation on the Corrosion of Steel

CORROSION ◽  
1970 ◽  
Vol 26 (5) ◽  
pp. 189-199 ◽  
Author(s):  
W. D. FRANCE
Keyword(s):  
Plastic Deformation ◽  
Electrochemical Techniques ◽  
Chloride Ions ◽  
Localized Corrosion ◽  
Dissolution Behavior ◽  
Potential Range ◽  
Chemical Corrosion ◽  
Effects Of Ph ◽  
Current Densities ◽  
The Stability

Abstract The rate and type of corrosion exhibited by mild steel in the annealed, stressed, and plastically deformed state have been investigated. Precise electrochemical techniques provided potential and polarization data to supplement the results of chemical corrosion tests. Experiments were conducted in 0.6M NH4NO3 solutions in which steel exhibits active-passive dissolution behavior as well as localized corrosion. At active potentials, the anodic polarization curves for annealed and deformed specimens were nearly identical, with only slight increases in current densities for the deformed steel. Results at passive potentials demonstrated that increased plastic deformation can markedly decrease the passive potential range, the stability of passivity, and the ability to passivate. At certain passive potentials, the deformed steel exhibited current densities that were 400 times greater than those for annealed steel. The effects of pH, chloride ions, and crevices on the corrosion of deformed steel were examined in detail. The differences between the dissolution behavior of annealed and deformed steel were most distinctive in the approximate pH range of 3 to 6. This work is relevant to the understanding of the initiation of localized corrosion and to anodic protection.

Electrochemical Behavior of Three-Dimensional Cobalt Manganate with Flowerlike Structures for Effective Roxarsone Sensing

2021 ◽  
Author(s):  
Thangavelu Kokulnathan ◽  
Veeramanikandan Rajagopal ◽  
Tzyy-Jiann Wang ◽  
Song-Jeng Huang ◽  
Faheem Ahmed
Keyword(s):  
Electrochemical Behavior ◽  
Three Dimensional

Electrochemical and thermodynamic properties of U4+ and U3+ on Mo electrode in LiCl-KCl eutectic

2019 ◽  
Vol 107 (2) ◽  
pp. 95-104
Author(s):  
Ru-Shan Lin ◽  
You-Qun Wang ◽  
Zhao-Kai Meng ◽  
Hui Chen ◽  
Yan-Hong Jia ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Thermodynamic Functions ◽  
Electrochemical Behavior ◽  
Diffusion Coefficients ◽  
Electrochemical Techniques ◽  
Reduction Process ◽  
Standard Potential ◽  
Hcl Gas ◽  
Thermodynamic Functions Of Formation

Abstract In this study, UCl4 was prepared by the reaction of HCl gas with UO2 in the LiCl-KCl eutectic. Then, the electrochemical behavior of U4+ and U3+ on a Mo cathode was investigated by various electrochemical techniques. The reduction process of U4+ was regarded as two steps: U4++e=U3+; U3++3e=U. Diffusion coefficients of U4+ and U3+, the apparent standard potential of U4+/U3+, U3+/U as well as U4+/U in the LiCl-KCl molten salt on the Mo electrode was determined by numerous electrochemical methods. The thermodynamic functions of formation of Gibbs free energy of UCl4 and UCl3 are calculated as well.

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