Electrodeposition of Tungsten from Molten KF–KCl–WO<sub>3</sub> and CsF–CsCl–WO<sub>3</sub>

Ide, Tatsuya; Meng, Xianduo; Norikawa, Yutaro; Yasuda, Kouji

doi:10.1149/1945-7111/abf266

Cited by 13 publications

(12 citation statements)

References 18 publications

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“…From the cyclic voltammogram in KF–KCl–WO 3 shown in Figure b, the cathodic current due to W deposition is observed at approximately 1.6 V vs K + /K. Galvanostatic electrolysis was then conducted at the Cu electrode Figure c shows the Cu electrode before and after electrodeposition.…”

Section: Electrodeposition Of Tungstenmentioning

confidence: 99%

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Norikawa

2023

Acc. Chem. Res.

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Conspectus This Account describes the results of the electrodeposition of film-like Si, Ti, and W by utilizing molten salts selected based on a new concept. The proposed molten salt systems, KF–KCl and CsF–CsCl, have high fluoride ion concentrations, relatively low operating temperatures, and high solubility in water. First, KF–KCl molten salt was used for the electrodeposition of crystalline Si films to establish a new fabrication method for Si solar cell substrates. The electrodeposition of Si films from the molten salt at 923 and 1023 K was successfully achieved using K2SiF6 or SiCl4 as the Si ion source. The crystal grain size of Si was larger at higher temperatures, indicating that higher temperatures are advantageous for the application of Si solar cell substrates. The resulting Si films underwent photoelectrochemical reactions. Second, the electrodeposition of Ti films using the KF–KCl molten salt was investigated to easily impart the properties of Ti, such as high corrosion resistance and biocompatibility, to various substrates. Ti films with a smooth surface were obtained from the molten salt containing Ti(III) ions at 923 K. Electrochemical tests in artificial seawater revealed that the electrodeposited Ti films had no voids and cracks and that the obtained Ti-coated Ni plate had a high corrosion resistance against seawater. Finally, the molten salts were used for the electrodeposition of W films, which are expected to be used as diverter materials for nuclear fusion. Although the electrodeposition of W films was successful in the KF–KCl–WO3 molten salt at 923 K, the surface of the films was rough. Therefore, we used the CsF–CsCl–WO3 molten salt, which can be employed at lower temperatures than KF–KCl–WO3. We then successfully electrodeposited W films with a mirror-like surface at 773 K. Such a mirror-like metal film deposition has not been reported before using high-temperature molten salts. Further, the temperature dependence of the crystal phase of W was revealed by the electrodeposition of W films at 773–923 K. β-W was obtained at 773 and 823 K, α-W was obtained at 923 K, and a mixed phase of α- and β-W was obtained at 873 K. In addition, single-phase β-W films with a thickness of approximately 30 μm were electrodeposited, which has not been reported before. The results show that our proposed molten salt systems are advantageous for electroplating Si, Ti, and W. Our approach is also expected to be applicable for the electrodeposition of other metals such as Zr, Nb, Mo, Hf, and Ta.

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Section: Electrodeposition Of Tungstenmentioning

confidence: 99%

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Norikawa

2023

Acc. Chem. Res.

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“…[1][2][3] The Na 2 WO 4 -WO 3 molten salt system is predominantly utilized for tungsten coating since WO 3 is stable and relatively easy to prepare. [4][5][6] Electrodeposition of tungsten with molten salts as a medium is an effective approach in the production of tungsten coatings [7][8][9][10][11][12] and has garnered considerable attention. [13][14][15][16][17][18] In terms of electrode selection, studies have suggested that copper electrodes in Na 2 WO 4 -WO 3 molten salt can produce dense tungsten coatings.…”

Section: Introductionmentioning

confidence: 99%

Effect of electric fields on tungsten distribution in Na₂WO₄–WO₃ molten salt

Guo,

Sun,

Jiao

et al. 2024

Phys. Chem. Chem. Phys.

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“…For example, according to research, 16 tungsten trioxide cannot be electrochemically reduced to tungsten metal in the eutectic melt of sodium and calcium chlorides without large losses, while the worksproof that this process can be implemented in molten mixtures of LiCl-KCl and KF-KCl, CsF-CsCl. 17,18 There is no information on large losses of tungsten due to the formation and sublimation of volatile tungsten compounds. Given the above, the study of the processes that occur during the electrochemical reduction of tungsten oxide is an important not only applied but also scientific task.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical reduction of tungsten (VI) oxide from a eutectic melt CaCl2-NaCl under potentiostatic conditions

Medvezhynska

Kuleshov

Bykov

et al. 2022

JSCS

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The paper presents results of a study of the electrochemical reduction of tungsten (VI) oxide in a melt of the eutectic composition 52 mol.% CaCl2 and 48 mol.% NaCl at a liquid gallium electrode. Scanning electron microscopy and X-ray diffraction methods were used to study the microstructures of the obtained powders. The Rietveld method which is based on diffraction patterns were used to calculate the quantitative content of phases in WO3 reduction products. The thermodynamic properties of the electrolysis process were investigated by voltammetry. It is shown that a necessary condition for the electrochemical reduction of WO3 is electrolysis at potentials higher than the standard electrode potential of decomposition of calcium tungstate, which is formed by the interaction of tungsten oxide with calcium chloride. The reduction can take place by both electrochemical and metallothermic mechanisms depending on the conditions of electrolysis. The reduction product is fine tungsten with a particle crystallite size of up to 1 ?m.

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Electrodeposition of Tungsten from Molten KF–KCl–WO₃ and CsF–CsCl–WO₃

Cited by 13 publications

References 18 publications

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Effect of electric fields on tungsten distribution in Na₂WO₄–WO₃ molten salt

Electrochemical reduction of tungsten (VI) oxide from a eutectic melt CaCl2-NaCl under potentiostatic conditions

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Electrodeposition of Tungsten from Molten KF–KCl–WO3 and CsF–CsCl–WO3

Cited by 13 publications

References 18 publications

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

A New Concept of Molten Salt Systems for the Electrodeposition of Si, Ti, and W

Effect of electric fields on tungsten distribution in Na2WO4–WO3 molten salt

Electrochemical reduction of tungsten (VI) oxide from a eutectic melt CaCl2-NaCl under potentiostatic conditions

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Product

Resources

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Electrodeposition of Tungsten from Molten KF–KCl–WO₃ and CsF–CsCl–WO₃

Effect of electric fields on tungsten distribution in Na₂WO₄–WO₃ molten salt