Search Results (30)

Molten salt electrodeposition is a promising technique to prepare high-performance tungsten coatings for fusion reactor first-wall components. However, the ultra-high temperature during deposition causes severe grain coarsening and precipitate dissolution in CuCrZr alloy substrates, resulting in dramatic mechanical property degradation. In this study, a thermal cycle at 1223.15 K for 100 h was employed to simulate the thermal impact of molten salt tungsten electrodeposition (MSE) on CuCrZr alloys, and an aging treatment (703.15 K for 12 h) was adopted to restore the degraded mechanical properties. After aging, the tensile strength and yield strength recovered to 378.35 ± 7.40 MPa and 261.02 ± 3.40 MPa, meeting the minimum tensile property requirements of ITER for CuCrZr alloys. The recovery is attributed to nano-sized Cr-rich phase precipitation and high-density dislocations, providing effective Orowan precipitation strengthening. This work provides the first simple, engineering-friendly post-treatment to repair performance degradation of CuCrZr under the extreme thermal exposure of molten salt electrodeposition, which is critical for large-scale fabrication of high-performance plasma-facing components (PFCs) for fusion reactors. Full article

The pyrometallurgical reprocessing of spent fuel developed by the United States is currently one of the most promising nuclear fuel reprocessing methods. The electroreduction, electrolytic refining, and electrodeposition processes involve electrochemical research in high-temperature molten chloride systems. In recent years, much progress has been made in simulating and studying molten-salt systems from a microscopic perspective using the first-principles molecular dynamics (FPMD) simulation technique. Using this method for simulation calculations is more conducive to analyzing the microscopic action mechanism and microscopic mechanism in the system from the atomic level and explaining the internal reasons for various electrochemical behaviors and phenomena. This opens up a new path for the study of molten-salt electrochemical systems. However, there are still a few systematic reviews of simulating work in first-principles computation. Therefore, this work summarizes the theoretical calculation work on molten-salt electrochemical systems of recent years, focusing on the research progress in computational aspects such as coordination properties, physical properties, and electrode behavior, which has good guiding value for the application of FPMD in molten-salt electrochemistry. Full article

Samarium, a rare earth element, is crucial for advanced technological applications, particularly due to the exceptional magnetic properties of Sm_xCo_y intermetallics, discovered over 50 years ago. However, its growing significance and demand have highlighted concerns about scarce, commercially viable natural sources and the complex separation processes needed to isolate it from other lanthanides. In this context, electrodeposition has emerged as a versatile method for both synthesizing samarium materials and recovering the element. A major obstacle in applying electrolysis lies in the complex electrochemical behavior of samarium species, stemming from their highly negative electrochemical potential. While this limits the use of aqueous solutions, it also opens up possibilities for alternative solvents, such as molecular liquids, ionic liquids, deep eutectic solvents, and molten salts. The electrochemical properties of samarium have prompted exploration into electrodeposition techniques for material synthesis and recycling. This review discusses various aqueous and non-aqueous electrolyte compositions, different electrolysis modes, and the role of cathode substrates. It also shows the potential of electrolysis in the fabrication of various cathode products (metal, alloys/intermetallics, inorganic compounds), highlighting both challenges and opportunities in its practical implementation. Full article

To address the issue in the pure oxide molten salt system Na₂WO₄-WO₃, where the relatively high melting temperature often causes thermal corrosion of the base material and reduces electrodeposition efficiency. A new molten salt system for electrodeposition tungsten coatings on CuCrZr substrates at relatively low temperatures was investigated. The crystal structure and microstructure of the tungsten coatings were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The results indicate that the power supply mode, current density, and duty cycle significantly affect the microstructure, crystalline characteristics, and overall performance of the tungsten coating. Pure tungsten coatings were successfully fabricated on CuCrZr substrates at 943 K. The best electrodeposition parameters were determined to be a current density of 40 mA/cm² and a duty cycle of 40%. Moreover, after prolonged electrodeposition (60 h), the tungsten coatings retained fine grains, with sizes ranging from 2 μm to 6 μm. Full article

Electrochemical deposition of silicon is considered a promising alternative to conventional high-temperature and high-emission methods of silicon production. This review analyzes the current state of research on electrolyte systems used for silicon electrodeposition, with a particular focus on their potential for industrial-scale application. These systems are evaluated based on key characteristics relevant to such implementation, including silicon precursor solubility, electrical conductivity, applicable current density, and behavior under process conditions. The study evaluates fluoride-based, chloride-based, mixed halide, and organic electrolyte systems based on key criteria, including conductivity, chemical stability, silicon precursor solubility, temperature range, and ease of product purification. Fluoride-based melts offer high current densities (up to 2 A/cm²) and effective SiO₂ dissolution but operate at high temperatures (550–1300 °C) and suffer from hygroscopicity. Chloride systems exhibit lower operating temperatures (300–1000 °C) and better water solubility but lack compatibility with common silicon sources. Mixed fluoride–chloride electrolytes emerge as the most promising option, combining high performance with improved practicality; they operate at 600–850 °C and current densities up to ~1.5 A/cm². Additional focus is placed on the impact of substrate materials and on unresolved questions related to reaction reversibility, kinetic mechanisms, and the influence of electrolyte composition. The review concludes that further fundamental studies are needed to optimize electrolyte design and enable the transition from laboratory-scale research to industrial implementation. Full article

Characteristics of electrodeposited tungsten coatings prepared at 1193 K and varying current density were investigated. The crystal structure and microstructure of tungsten coatings were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and photoelectron spectroscopy (XPS). The results indicated that pulsed current density significantly influence the tungsten nucleation and electro-crystallization phenomena. The average grain size of the coating becomes larger with increasing current density, which demonstrates that appropriate high cathodic current density can accelerate the growth of grains on the surface of the substrate. The micro-hardness of tungsten coatings increases with increasing thickness and then slightly decreases; the maximum micro-hardness is 589.55 HV, with the oxygen content remaining below 0.03 wt%. Full article

The pulsed current electrodeposition method was employed for the first time to achieve tungsten coating with a thickness of 433.72 μm on a CuCrZr alloy from Na₂WO₄-WO₃-KCl-NaF molten salt. The microstructure of the coating was observed and the coating density, porosity, hardness, bonding strength, residual stress and oxygen content were tested. The results revealed that the tungsten coating exhibited desirable characteristics such as high density, absence of impurities, excellent adhesion to the matrix (53.16 MPa), residual compressive stress as surface stress, and good stability and durability. Moreover, this thick tungsten coating possesses high density and hardness, low oxygen content and porosity. This offers a novel solution to solve the challenging issue of the connection between tungsten material and heat sink material. Full article

A molten salt system was prepared using an optimized method. We studied the complex structure of Ir³⁺ ions in the molten salt system and the influence their concentration had on the quality of the coatings prepared via electrodeposition. Using TG-DSC and in situ XRD experiments, we studied the high-temperature characteristics and properties of IrCl₃ alongside its thermal stability. Using in situ XRD and Raman spectroscopy, we analyzed the Ir ions’ complex structure and the variation in the molten salt system at high temperatures. Finally, the changes in the Ir ion concentration in the molten salt system and the influence of the microstructure of the coatings’ surfaces were investigated under different anode conditions. IrCl₃ easily decomposes above 400 °C, and temperature increases accelerate the rate of this decomposition. When the NaCl-KCl-CsCl system is in a high-temperature, molten state, IrCl₃ forms stable complex structures (IrCl₆)³⁻ and (IrCl₆)²⁻, and the valence state of Ir will be transformed with the increase in temperature. Generating these complex structures is conducive to improving the Ir coating quality. During the electrodeposition process, too few Ir ions in the molten salt can lead to concentration polarization, affecting the quality of the coating. Application of the molten NaCl-KCl-CsCl system is conducive to the electrodeposition of Ir coatings in a suitable temperature range. At the same time, using Ir as the anode can enhance the quality of the coatings. Full article

The presented paper characterized the molten salt-modified Ni electrode with excellent catalytic activity towards alkaline urea electrooxidation reaction. The electrodes were modified by electrodeposition of Al from molten salt electrolytes containing NaCl-KCl-AlF₃ at a temperature of 750 °C and applied potential of −1.9 V. The porous surface was obtained by anodic polarization with a potential of −0.4 V until the anodic current was equal to 0 mAcm⁻². The prepared deposits’ structure, surface morphology, and composition were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Anodic polarization was applied to assess the electrocatalytic activity and elucidate the urea electrooxidation mechanism in 1 M KOH + 0.33 M urea solution. The nanocrystalline structure, fine grain size, and microcracks on the surface of the studied electrodes contributed to their notably high electrochemically active surface area (ECSA). The cyclic voltammetry in the non-Faradaic regions of the samples shows that molten salt modification can increase the double layer capacitance of bare Ni plates by around ten times, from 0.29 mFcm⁻² to 2.16 mFcm⁻². Polarization of the electrodes in urea-containing KOH solution with potential of +1.52 V shows a significant difference in catalytic performance. For the bare nickel sample, the registered current density from the urea electrooxidation reaction was around +1 mAcm⁻², and for the molten salt-modified one, it was +38 mAcm⁻², which indicates the fact that the molten salt surface treatment can be a promising tool in tailoring the electrochemical properties of materials. Full article

Molten salt electrodeposition is the process of producing impressively dense deposits of refractory metals using the electrolysis of molten salts. However, predicting which electrochemical parameters and setup will best control different kinds of deposition (density, homogeneity, etc.) is an ongoing challenge, due to our limited understanding of the properties and mechanisms that drive molten salt electrodeposition. Because these advancements have been made rapidly and in different arenas, it is worth taking the time to stop and assess the progress of the field as a whole. These advancements have increasing relevance for the energy sector, the development of space materials and engineering applications. In this review, we assess four critical facets of this field: (1) how the current understanding of process variables enhances the electrodeposition of various molten salts and the quality of the resulting product; (2) how the electrochemical setup and the process parameters (e.g., cell reactions) are known to impact the electrodeposition of different metal coatings and refractory-metal coatings; (3) the benefits and drawbacks of non-aqueous molten salt electrodeposition, and (4) promising future avenues of research. The aim of this work is to enhance our understanding of the many procedures and variables that have been developed to date. The expectation is that this review will act as a stimulant, motivating scientists to delve further into the investigation of refractory-metal alloys by utilizing molten salt electrodeposition. Full article

In this paper, electrodeposition of a molybdenum coating was conducted in Na₃AlF₆-NaF-Al₂O₃-MoO₃ molten salts at 930 °C to investigate the availability of preparation of thick molybdenum coatings. The effects of current density and electrodeposition time on the morphology of the produced molybdenum coating were studied. With the increase of current density (10~70 mA·cm⁻²), the coating thickness was increased from 10 μm to 30 μm, with all the current efficiency above 97%. Under a current density of 30 mA/cm², with the rise of electrodeposition time (10~60 min), three stages of the deposit growth were observed, including the formation of a large number of fine crystals, transformation into fibrous morphology and well-developed faceted grains. The formation of a large number of fine crystals at the initial stage of the electrodeposition could facilitate electroplating molybdenum coatings with good quality at higher current density and longer duration. Thus electrodeposition at a current density of 100 mA·cm⁻² for 3 h has been performed, resulting in the preparation of relatively flat, dense, and coherent molybdenum coatings with a thickness of 140 μm on a nickel substrate, with a current efficiency above 85%. It is anticipated that the electrodeposition of molybdenum coatings in the present molten system is suitable for electroplating thick molybdenum coatings. Full article

The hardness and wear resistance of amorphous Al–Mn alloy coatings can be improved by incorporating ceramic particles into them to extend their application. In this paper, Al–Mn/WC composite coatings have been prepared with electrodeposition in stirred AlCl₃–NaCl–KCl–MnCl₂ molten salts at 180 °C with the addition of WC particles. The effects of stirring speed (400–700 rpm) and cathode current density (15–75 mA/cm²) on the produced Al–Mn/WC composite coatings have been studied. At 600 rpm and 700 rpm, the Al–Mn/WC composite coatings exhibited the best uniform distribution of the embedded WC particles, with the tested microhardness value up to 650 HV_0.1, compared with 530 HV_0.1 of the Al–Mn alloy. Moreover, under various cathode current densities, the best quality of the Al–Mn/WC composite coating was obtained at 55 mA/cm², with a homogeneous distribution of WC particles and the highest microhardness value (670 HV_0.1). It is expected that this method could be extended to be applied for the preparation of aluminum-based and magnesium-based ceramic composite coatings. Full article

Silicon carbide is successfully implemented in semiconductor technology; it is also used in systems operating under aggressive environmental conditions, including high temperatures and radiation exposure. In the present work, molecular dynamics modeling of the electrolytic deposition of silicon carbide films on copper, nickel, and graphite substrates in a fluoride melt is carried out. Various mechanisms of SiC film growth on graphite and metal substrates were observed. Two types of potentials (Tersoff and Morse) are used to describe the interaction between the film and the graphite substrate. In the case of the Morse potential, a 1.5 times higher adhesion energy of the SiC film to graphite and a higher crystallinity of the film was observed than is the case of the Tersoff potential. The growth rate of clusters on metal substrates has been determined. The detailed structure of the films was studied by the method of statistical geometry based on the construction of Voronoi polyhedra. The film growth based on the use of the Morse potential is compared with a heteroepitaxial electrodeposition model. The results of this work are important for the development of a technology for obtaining thin films of silicon carbide with stable chemical properties, high thermal conductivity, low thermal expansion coefficient, and good wear resistance. Full article

The results obtained from the work on a concept of a recycling process for NdFeB magnets to recover rare earth elements for remanufacturing similar magnets are presented. This paper investigates the viability of extracting rare earth metals from magnet recycling-derived oxide (MRDO) by means of molten salt electrolysis. The MRDO was produced from spent NdFeB magnets through oxidation in air and subsequently carbothermic reduction under an 80 mbar Ar gas atmosphere. This MRDO contained roughly 33 wt.% Nd and 10 wt.% Pr. The electrochemical reduction process of the MRDO on molybdenum electrodes in NdF₃ + LiF and NdF₃ + PrF₃ + LiF fused salts systems was investigated by cyclic voltammetry and chronoamperometry measurements. The resulting electrolytes and electrodes were examined after potentiostatic deposition by scanning electron microscopy (SEM), inductively coupled plasma optical emission spectroscopy (ICP-OES), and X-ray diffraction (XRD) analysis. The electrodeposited metals appeared to accumulate on the cathode and X-ray diffraction analysis confirmed the formation of metallic Nd and Pr on the working substrate. The suitability of the obtained alloy intended for the remanufacturing of NdFeB magnets was then evaluated. Full article

Ni coatings with high catalytic efficiency were synthesised in this work, obtained by increasing the active surface and modifying Pd as a noble metal. Porous Ni foam electrodes were obtained by electrodeposition of Al on a nickel substrate. Deposition of Al was carried out with potential −1.9 V for a time of 60 min in NaCl–KCl-3.5 mol%AlF₃ molten salt mixture at 900 °C, which is connected with the formation of the Al-Ni phase in the solid state. Dissolution of Al and Al-Ni phases was performed by application of the potential −0.5 V, which provided the porous layer formation. The obtained porous material was compared to flat Ni plates in terms of electrocatalytic properties for ethanol oxidation in alkaline solutions. Cyclic voltammetry measurements in the non-Faradaic region revealed the improvement in morphology development for Ni foams, with an active surface area 5.5-times more developed than flat Ni electrodes. The catalytic activity was improved by the galvanic displacement process of Pd(II) ions from dilute chloride solutions (1 mM) at different times. In cyclic voltammetry scans, the highest catalytic activity was registered for porous Ni/Pd decorated at 60 min, where the maximum oxidation peak for 1 M ethanol achieved +393 mA cm⁻² compared to the porous unmodified Ni electrode at +152 mA cm⁻² and flat Ni at +55 mA cm⁻². Chronoamperometric measurements in ethanol oxidation showed that porous electrodes were characterised by higher catalytic activity than flat electrodes. In addition, applying a thin layer of precious metal on the surface of nickel increased the recorded anode current density associated with the electrochemical oxidation process. The highest activity was recorded for porous coatings after modification in a solution containing palladium ions, obtaining a current density value of about 55 mA cm⁻², and for a flat unmodified electrode, only 5 mA cm⁻² after 1800 s. Full article