Electrochemical synthesis of hafnium silicides

Кузнецова, С. В.; Kuznetsov, S. A.

doi:10.1134/s1023193509070064

Cited by 27 publications

(57 citation statements)

References 8 publications

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“…However, this can be done using the LFER principle and a combination of adsorption and corrosion-electrochemical measurements. As early as in 1980, we identified a linear dependence of the logarithm of protective concentrations of substituted benzimidazoles [4,15], and later of thiazoles [16], on copper and zinc in a phosphate solution at pH 11.7, on induction constants (σ I ) of R in the inhibitor molecules. 3 Protection of copper becomes more efficient when R is an electron acceptor (σ I >0), whereas protection of zinc is favored by electron-donor R's (σ I <0).…”

Section: Adsorption Of Corrosion Inhibitors On Metals and Passivationmentioning

confidence: 95%

Progress in the science of corrosion inhibitors

Kuznetsov

pr.²,

Moscow³

et al. 2015

Int. J. Corros. Scale Inhib.

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The physicochemical features of corrosion inhibition of metals (alloys) strongly depend on the composition of the corrosive environment, its pH, temperature t, hydrodynamic conditions, the chemical nature of the metal to be protected, and the state of its surface, the presence of oxides, dirt, or corrosion products on it. This "multifactor" nature of corrosion seriously complicates the theoretical choice of an efficient corrosion inhibitor (CI), often requiring careful experimental studies and creating unjustified skepticism about the fundamental character of the physical chemistry area related to the study and development of CIs. Meanwhile, this skepticism can be proved wrong by the progress made over the past quarter century in various subareas. Key words: corrosion inhibitors, adsorption, metal passivation, volatile corrosion inhibitors, migrating inhibitors, local depassivation of metals, protecting coatings. Adsorption of corrosion inhibitors on metals and passivationAdsorption on a protected surface is the first event that often determines CI efficiency. Difficulties of its measurement in situ are caused by dissolution and/or oxidation of the metal substrate with time. The uncertainty in separating the effects of adsorption and changes of the state of the metal surface often does not permit to unambiguously interpret the results obtained, for example, by electrochemical impedance spectroscopy (EIS) or using radioactive tracers. In his first "Inhibitors of corrosion of metals in neutral media" (1953), I.L. Rozenfel'd considered only inorganic CIs. He remained interested in these inhibitors throughout his whole life, so it is not surprising that in his latest book "Corrosion Inhibitors" (1977) he reexamined the interaction of some inorganic CIs, primarily chromate, with the metal at a more modern level, including a quantum-chemical approach. However, studies on the

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Section: Adsorption Of Corrosion Inhibitors On Metals and Passivationmentioning

confidence: 95%

Progress in the science of corrosion inhibitors

Kuznetsov

pr.²,

Moscow³

et al. 2015

Int. J. Corros. Scale Inhib.

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“…Researchers have studied electrodeposition of elemental boron from various boron containing melts [10][11][12][13][14][15][16][17][18][19][20][21][22]. In this context fluoroborate containing melts have been extensively studied [23][24][25][26][27][28][29][30]. The reduction of B(III) in NaCl-KCl-MBF 4 (M = Na and K) melts was studied by Taranenko et al [25].…”

Section: Introductionmentioning

confidence: 99%

Insights into the Electrochemistry of Deposition of Boron from KCl-KF-NaBF4 Melt

Pal¹,

Anthonysamy²

2015

Port. Electrochim. Acta

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Electrochemical reduction of boron from boron containing fluoroborate species present in KCl (81.54 mol%)-KF (18.45 mol%)-NaBF 4 (1.67x10 -4 mol cm -4 ) melt on a platinum electrode was studied by cyclic voltammetry and chronoamperometry. These studies were carried out over the temperature range 1073 -1123 K. Boron-containing electroactive species is shown to reduce quasi-reversibly at low scan rates (ν < 0.1 Vs -1 ) and irreversibly at higher scan rates (> 0.1 V s -1 ) through a single-step three-electron process (B(III) + 3e → B). The transfer and diffusion coefficients of the electroactive species was measured for sodium fluoroborate in KCl-KF melt over the temperature range 1073-1123 K.

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“…6 The NaCl-KCl melt has a higher melting than the LiCl-KCl one; therefore, the niobium pentachloride electrochemical reduction is a two-stage process, with a consecutive transfer of one and four electrons according to the Equations 1 and 2. [6][7][8]13 However, there is no data on the standard rate constants of charge-transfer for the Nb(V)/Nb(IV) redox couple.…”

Section: Nbmentioning

confidence: 99%

“…The NaCl-KCl melt has a higher melting than the LiCl-KCl one; therefore, the niobium pentachloride electrochemical reduction is a two-stage process, with a consecutive transfer of one and four electrons according to the Equations 1 and 2. [6][7][8]13 However, there is no data on the standard rate constants of charge-transfer for the Nb(V)/Nb(IV) redox couple.In this work we aimed at the determining of the standard rate constants of charge transfer for the Nb(V)/Nb(IV) redox couple in the following chloride systems: NaCl-KCl (equimolar mixture)-NbCl 5 , KCl-NbCl 5 and CsCl-NbCl 5 at glassy carbon and platinum electrodes.Previously, in Refs. 14-17 quantum- complexes consistent with the change of the experimental standard rate constants of charge transfer in a series of molten salts type (Na-K)Cl eq.…”

mentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Electrochemical reduction of niobium in LiCl-KCl-NbCl 5 and NaCl-KCl-NbCl 5 melts was also studied 6 and the temperature effect on the niobium electrochemical behavior in LiCl-KCl melt was elucidated. The three cathodic waves observed in the 673-903 K temperature range were interpreted as consecutive transfer of one electron and two electrons in the two consecutive reaction stages.…”

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confidence: 99%

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Intervalence Charge Transfer of the Nb(V)/Nb(IV) Redox Couple in Alkali Chloride Melts: Experiment and Quantum-Chemical Calculations

Popova

Kremenetsky

Kuznetsov

2017

J. Electrochem. Soc.

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The standard rate constants of charge transfer (k s ) for the Nb(V)/Nb(IV) redox couple in KCl-NbCl 5 and CsCl-NbCl 5 chloride melts have been determined. The redox process in the NaCl-KCl-NbCl 5 melt was shown being reversible; hence, the determination of k s appeared impossible. Values of k s in the KCl-NbCl 5 melt are larger than in the CsCl-NbCl 5 melt. Previously, a quantum-chemical calculations of nM + · [NbCl 6 ] model systems (M = Na, K, Cs), containing a complex anion with cations outer-sphere (OS) shell (nM + ) have been done. It was found that compositions with an intermediate number of OS cations n < n lim , where n lim is the limiting number of OS cations bound to a given complex, are thermodynamically most stable. In this study a quantum-chemical calculations were performed for estimation of the temperature effect on the composition of the stable particles in the extended systems M + · [NbCl 6 ]+18MCl (M = Na, K, Cs Possible schemes of niobium reduction in chloride melts of different composition were discussed at length.1-13 Electrochemical reduction of niobium in LiCl-KCl-NbCl 5 and NaCl-KCl-NbCl 5 melts was also studied 6 and the temperature effect on the niobium electrochemical behavior in LiCl-KCl melt was elucidated. The three cathodic waves observed in the 673-903 K temperature range were interpreted as consecutive transfer of one electron and two electrons in the two consecutive reaction stages. Importantly, the electrochemical reduction in the second stage is accompanied by formation of insoluble in the melt products with the composition ranging from NbCl 2.33 to NbCl 3.13 . At temperatures from 903 to 923 K the lower chlorides become thermodynamically unstable; at 923 K a two-stage electrode process occurred:Later on, data on the niobium cluster compounds formation were confirmed; 7,8 these compounds were found decomposing at 923 K, in full agreement with the previous data. The NaCl-KCl melt has a higher melting than the LiCl-KCl one; therefore, the niobium pentachloride electrochemical reduction is a two-stage process, with a consecutive transfer of one and four electrons according to the Equations 1 and 2. [6][7][8]13 However, there is no data on the standard rate constants of charge-transfer for the Nb(V)/Nb(IV) redox couple.In this work we aimed at the determining of the standard rate constants of charge transfer for the Nb(V)/Nb(IV) redox couple in the following chloride systems: NaCl-KCl (equimolar mixture)-NbCl 5 , KCl-NbCl 5 and CsCl-NbCl 5 at glassy carbon and platinum electrodes.Previously, in Refs. 14-17 quantum- complexes consistent with the change of the experimental standard rate constants of charge transfer in a series of molten salts type (Na-K)Cl eq. -KCl-CsCl. For such systems, the second coordination sphere of the complex (the OS shell) consist of cations Na, K, and Cs, respectively. Estimated value of the E act in this row usually decreases. This is true in the case when the charge transfer mechanism is the same in all systems. In such systems, the change of the reorga...

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Electrochemical synthesis of hafnium silicides

Cited by 27 publications

References 8 publications

Progress in the science of corrosion inhibitors

Progress in the science of corrosion inhibitors

Insights into the Electrochemistry of Deposition of Boron from KCl-KF-NaBF4 Melt

Intervalence Charge Transfer of the Nb(V)/Nb(IV) Redox Couple in Alkali Chloride Melts: Experiment and Quantum-Chemical Calculations

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