The Electrodeposition of Coherent Deposits of Refractory Metals

Mellors, G. W.; Senderoff, S.

doi:10.1149/1.2423865

Cited by 88 publications

(35 citation statements)

References 14 publications

(16 reference statements)

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“…30 Nevertheless, one important point seems to be the potential reactivity of KF with Zr to form potassium metal. 28 Therefore, the presence of KF is undesirable from the operation point of view.…”

mentioning

confidence: 99%

Study of the Electrochemical Reduction of Zr[sup 4+] Ions in Molten Alkali Fluorides

Groult

Barhoun

Ghallali

et al. 2008

J. Electrochem. Soc.

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The electrochemical behavior of Zr 4+ in potassium-free fused alkali fluorides has been studied in the temperature range of 773-1123 K. With an inert tungsten or molybdenum electrode, a well-defined oxydo-reduction wave was observed during cyclic voltammetry experiments. The reduction of Zr 4+ is a single four-electron reversible step, and the process is diffusion controlled. Chronopotentiometry measurements give rise to the diffusion coefficient values of Zr 4+ ions. For instance, a value 2.92 ϫ 10 −5 cm 2 s −1 was found at 1010 K. The reduction of Zr 4+ ions was also studied using a nickel electrode for which Ni-Zr alloys formation was pointed out as revealed by cyclic voltammetry. The analysis of these deposits by scanning electron microscopy ͑SEM͒ and energy dispersive X-ray showed the presence of a multilayered Ni-Zr alloy with different Zr contents. On graphite electrodes, zirconium carbides have been evidenced on cyclic voltammograms and the formation of Zr metal was observed by SEM.The pyroelectrochemical route is considered as one of the most promising options in an innovative nuclear fuel cycle. 1 Indeed, this process allows the separation of actinides from lanthanides by electrorefining in fused electrolytes. 2-7 For instance, Lantelme et al. 5 have performed the extraction of lanthanum in fused alkali chlorides via the formation of La-Ni alloys using Ni and Ni-Ti alloyed electrodes. Recently, Massot et al. have reported the formation of Sm-Ni alloys in molten LiF-CaF 2 . 6 Several studies have also been devoted to the electrochemical behavior of Zr ions in fused LiClKCl due to the electrorefining of binary U-Zr Experimental Breeder Reactor II driver fuel. 8,9 In this refining process, Zr is commonly considered as a nuisance 10 due to its slightly higher potential than uranium. 9,11,12 Consequently, the current efficiency for the actinides recovering is significantly decreased by the Zr dissolution and, thus, the electrochemical behavior of Zr in such a medium was widely studied.The interest devoted to the preparation of Zr and Zr-based alloys is also because these materials can be used for various applications, such as corrosion-resistant materials or as catalysts in various processes, such as for example, for the hydrogen evolution reaction. 13 For example, when H 2 is used as a fuel in small fuel cells, it is a convenient way to store it is as a hydride because it is compact and easy to operate. A typical metal hydride uses an AB 2 -type alloy, where A is, for example, Zr or Zr-Ti alloys and B is a mixture of transition metals. 14 Another original use of stainless steel-zirconium alloys was proposed by Argonne National Laboratory 15 for the express purpose of immobilizing radioactive metal fuel components left behind following the electrometallurgical treatment of spent nuclear fuel. 16 Such materials have been proposed for the consolidation and the disposal of waste stainless steel, Zr, and noble metalfission products, such as Nb, Mo, Tc, Ru, Pd, and Ag recovered from spent nuclear fuel assemblies....

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mentioning

confidence: 99%

Study of the Electrochemical Reduction of Zr[sup 4+] Ions in Molten Alkali Fluorides

Groult

Barhoun

Ghallali

et al. 2008

J. Electrochem. Soc.

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“…Information on the formation potentials in reactions [3], [4], and [5] may be obtained by thermodynamic cycles using available Gibbs free energies for the reactions given below as From reactions [6] and [7], by addition, reaction [3] is readily obtained, for which where AGO, is the Gibbs free energy of formation of pure solid A2MC16, as in reaction [3].…”

Section: Methodsmentioning

confidence: 99%

“…From reactions [6], [7], [8], and [9], reaction [4] is readily derived for which where AG: is the Gibbs free energy of formation of pure molten A,MC16, as in reaction [4].…”

Section: Methodsmentioning

confidence: 99%

Reversible electrode potentials for formation of solid and liquid chlorozirconate and chlorohafnate compounds

Kipouros¹,

Flengas²

1993

Can. J. Chem.

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functions of the mole fractions of the alkali hexachlorocompounds. Standard potentials for the above reaction and "formal" potentials are also given. The latter are useful in predicting the electrochemical behaviour of dilute solutions of the hexachlorozirconates in alkali metal chlorides. G.J. KIPOUROS et S.N. FLENGAS. Can. J. Chern. 71, 1283 (1993). Utilisant les pressions de vapeur correspondantes i leur decomposition thermique 21 l'kquilibre ainsi que des donnees thermochimiques disponibles, on a calcule les potentiels standard d'klectrode pour la formation des composts purs solide ainsi que fondu suivants : LizZrC16, Li2HfC16, Na2ZrC16, Na2HfC16, K2ZrC16, K2HfCl6, CsaZrC16 et Cs2HfCl6. o n a calcule les potentiels reversibles pour la formation du NazZrC16 et du K,ZrC16 en solution, selon la reaction :dans laquelle A represente Na ou K; pour ce faire, on a utilisk les Cquilibres disponibles de tension de vapeur en fonction des fractions molaires des composes hexachloroalcalins. On rapporte aussi les potentiels standard et ((formels,, des reactions mentionnees ci-dessus. Les derniers sont utiles pour prtdire le comportement Clectrochimique de solutions diluees d'hexachlorozirconates dans des chlorures de metaux alcalins.[Traduit par la redaction]

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“…Raising the electrolysis temperature, for example, lowers the voltage required to maintain a g~Ven cell current density (4). Raising the electrolysis temperature, for example, lowers the voltage required to maintain a g~Ven cell current density (4).…”

Section: Vow I28 Nomentioning

confidence: 99%

High Rate Electrodeposition of Niobium from Molten Fluorides Using Periodic Reversal Steps and the Effects on Grain Size

Cohen

1981

J. Electrochem. Soc.

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Application of periodic reversal (PR) technique, in which a cathodic (depositing) step is followed by an anodic (polishing) step, was found very beneficial to the increase of electroplating rate of coherent niobium. With no mechanical agitation, the application of the PR technique facilitated an electroplating rate increase by a factor of about 10 over the direct current method. The morphology of the deposits was found to be of the columnar structure. The columns became more oriented along the [100] direction, and of smaller diameters as the rate of electrodeposition increased. Unexpectedly, beyond a certain rate and under certain conditions, the columnar grains became large once again. Under such conditions a pronounced heteroepitaxial effect of the substrate (Cu) grains on the deposit grain size and orientation was observed.

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The Electrodeposition of Coherent Deposits of Refractory Metals

Cited by 88 publications

References 14 publications

Study of the Electrochemical Reduction of Zr[sup 4+] Ions in Molten Alkali Fluorides

Study of the Electrochemical Reduction of Zr[sup 4+] Ions in Molten Alkali Fluorides

Reversible electrode potentials for formation of solid and liquid chlorozirconate and chlorohafnate compounds

High Rate Electrodeposition of Niobium from Molten Fluorides Using Periodic Reversal Steps and the Effects on Grain Size

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