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The electrochemical behavior of Nd fluoride complexes for Nd electrowinning has been investigated according to the electrolyte composition in the LiF-NdF3 system. The electrochemical characteristics of the LiF-NdF3 electrolyte at low oxygen potential under acidic conditions and the LiF-NdF3-Nd2O3 electrolyte at high oxygen potential under basic conditions were also studied. The Nd fluoride complex behavior in the electrolyte was investigated by cyclic voltammetry for a concentration change of NdF3 with LiF at 1100 °C from 10 wt% to 64.6 wt%. The experimental results indicated that NdF3 is reduced to Nd(0) via a multi-step process. NdF2 could be produced by the comproportionation reaction between NdF3 and Nd metal. Additionally, the rate equation for NdF2 generation was derived through a reactivity test between the metal and the Nd2O3-free electrolyte. However, NdF2 production was suppressed in LiF-NdF3-Nd2O3 electrolyte.

A novel on-board hydrogen generation concept using Al coil with NaOH was investigated. The reaction rate was successfully controlled by introducing a pumping system for the NaOH solution. The time for the flow to develop fully was mainly dependent on the solution temperature, and the fastest start time recorded was 60 sec at a solution temperature of 70°C. The maximum H2 generation rate was 200 L min–1 with a prototype design of the on-board hydrogen generation system 1/8 times the size of a full-size reactor. The H2 generation process coupled with the solution pumping system was simulated with three-dimensional fluid dynamic software, and the calculated H2 flow and temperature rise of the system were validated with experimental data.

Amorphous boron nanoparticles were synthesized by heating a B 2 O 3 + 3 Mg + k NaCl ( k is the number of moles of NaCl) exothermic mixture in a laboratory oven at 800 °C under argon flow. NaCl was used as inert material to decrease the maximum combustion temperature of the reaction mixture when it was self-ignited after the melting of Mg at 650 °C. The size of the boron nanoparticles extracted from the final product by acid leaching ranged between 30 and 300 nm for k values ranging from 1 to 5. Moreover, increasing the value of k from 1 to 5 resulted in an increase in the specific surface area of the nanoparticles from 40 to 74 m 2 g −1 . However, at k = 10, a decrease in the specific surface area to 47.56 m 2 g −1 was recorded due to incomplete reduction of B 2 O 3 . The ignition point of boron nanoparticles in air as estimated using a thermocouple was approximately 300 °C. Digital camera recording of the combustion process of boron nanoparticles in air revealed that the burning speed of the nanoparticles increased significantly from 0.3 to 15 cm/s when k increased from 1 to 5.

Pyroprocessing, which results in proliferation resistance, shows promise as an alternative to wet processing in the recycling of transuranics. However, the ceramic crucible used in the electrowinning process poses an issue during pyroprocessing. The crucible is chemically unstable and prone to thermal fatigue. In this study, the thermodynamic simulation software HSC (enthalpy, entropy and heat capacity) Chemistry was employed to evaluate the chemical stabilities of different ceramic crucibles containing liquid cadmium as well as liquid bismuth cathodes, which also contained rare earth elements and lithium. The chemical stabilities were experimentally validated by measuring the contact angles between the liquid cathode (LC) materials and four ceramic materials (Al2O3, MgO, Y2O3, and BeO) in situ. The infiltration depths of the liquid bismuth cathode elements were measured using X-ray photoelectron spectroscopy. To determine the Weibull distributions of the investigated ceramics, thermal fatigue tests were ...

High-purity Nd metal was recovered from waste Nd–Fe–B magnet by the molten salt electrowinning process with chemical pretreatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), cyclic voltammetry (CV), chronopotentiometry (CP), and inductively coupled plasma-atomic emission spectrometer (ICP/AES) were used to characterize the deposit and electrochemical behaviors. The results show that NdF3 is effectively synthesized from the Nd–Fe–B magnet using HCl solution and NH4F. During the chemical treatment of the waste magnet, iron impurity is eliminated as a soluble [NH4]3[FeF6] complex. Electrowinning using NdF3 in LiF molten salt shows that Nd metal is deposited from the electrolyte on the cathode at the reduction potentials ranging from −1.48 to −1.35 V (vs. W) with the concentration change of NdF3. The final purity of Nd metal deposit is higher than 99.78 %.

LCC (Liquid cadmium cathode) is used for electrowinning in pyroprocessing to recover uranium and tran-suranic elements simultaneously. It is one of the core technologies in pyroprocessing with higher prolifera-tion resistance than a wet reprocessing because LCC-cell does not separate TRU from uranium. The cru-cible which holds the LCC is technically important because it should be nonconducting material to prevent deposition of metallic elements on the crucible outer surface. The chemical stability is also crucial factor to choose crucible material due to the strong reactivities of TRU and possible incorporation of Li metal during the operation. In this study, the chemical stabilities of four kinds of representative ceramic materi-als such as Al

We studied the purification of metallurgical grade Si from solutions of K2SiF6 in fluoride melts using a molten salt electrorefining process at 700 °C. Electrorefining close to the deposition potential gave dense, coherent, and well-adherent deposits. It was shown that the deposition rate and microstructure of Si strongly depend on the process temperature. Deposited polycrystalline silicon has a well defined rod shape and crooked structure that varies with current density. The anodic dissolution rate is affected by the initial concentrations of K2SiF6 and the applied current density. The results of an inductively coupled plasma (ICP) analysis indicated that recovered silicon fiber deposits with purities greater than 99.98% can be obtained using the developed technique. The morphology of the electrodeposited silicon on silver substrates is discussed in the context of a cathodic reaction on the electrode surface, and a comprehensive explanation of the purification mechanism with salt removal is provided.

Zirconium-based ceramics and composites such as ZrC, ZrB2, ZrC–SiC, ZrB2–SiC–ZrC, and ZrB2–SiC–ZrC–ZrSi were synthesized in fine powder form via combustion synthesis (CS) using ZrSiO4, Mg, C, B, and NaCl as raw materials. Temperature distributions in the combustion wave were measured by thermocouples and used to estimate the combustion temperature and wave propagation velocity. The influence of the NaCl mole fraction on the combustion parameters, phase composition, and particle size of the composite powders was investigated. The experimental results revealed that the combustion temperature and particle size of the composites have a stable decreasing tendency with increase in the NaCl mole fraction in the starting mixture. It was found that near the combustion limit (1.5 mol NaCl), the combustion temperature drops below 1500 °C and the particle size reaches the nanometer scale.

The effect of Si content in Al–Si alloy powder with NaOH on H 2 production was investigated. The total amount of H 2 produced decreased as Si content increased, which is inconsistent with the results predicted by the chemical reaction. Si caused a delay in the rate of H 2 production. Energy dispersive spectrometry showed that a large amount of unreacted Si remained in the matrix, and the unreacted fraction increased as the Si content increased. As the evolution reaction of Al and Al–Si alloys is exothermic, the temperature of all the specimens increased. Si addition reduced the hydroxide removal rate, which decreased the average H 2 production rate. The initiation time for H 2 evolution depends on the elimination rate of the oxide film formed during production of the powder. On increasing the Si content, SiO 2 was formed, which is harder to eliminate than Al 2 O 3 ; this delayed the initiation.

This study deals with research on the reduction process of neodymium oxide by molten salt electrowinning. Neodymium fluoride and lithium fluoride electrolyte were used for feed stock of electrolyte and neodymium oxide was added as precursor. Cell current was confirmed that cell potential was applied as constant potential of 4.5V. Argon gas injection into the electrolyte was carried out to confirm convection effect on current efficiency. Applied current was gradually decreased without argon flow, but applied current was kept within a certain range with argon flow in electrolyte.

This study deals with research on the reduction process of neodymium compounds by electrochemical process. Neodymium fluoride was synthesized from neodymium oxide by chemical reaction, thus prepared neodymium fluoride was used for feed stock of electrolyte for electrowinning based on lithium fluoride electrolyte. Electrochemical properties of neodymium were measured according to the concentration of neodymium ion by cyclic voltammetry at 1050 °C . The performance of the electrowinnig cell was evaluated by chronopotentiometry. Neodymium metal is deposited from electrolyte to cathode. Composition and morphology of the deposits was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Neodymium metal was deposited by molten salt electrorwinning process.

Tellurium is one of the most important materials in thermoelectric industries such as IT, home appliances, display devices, renewable energy, and parts of an automobile. High purity tellurium is required to provide the minimum levels of impurities for better characteristics of these products. The purification method for refining of high purity tellurium using zone refining is described. Trace impurities are analyzed using inductively coupled plasma atomic emission spectrometer(ICP-AES). In the zone refining process, optimum processing parameters were determined through a series of experiments on the traveling rate of heating zone and number of the passages.

Nd-Fe-B permanent magnets have been used in a wide variety of applications because of their high magnetic flux density. So, demand for neodymium has been increasing in worldwide. In this study, an electrowinning process was performed in high temperature molten salts. However, a corrosion resistant material for use in the molten salt must be found for stable operation because of the harsh corrosion environment of the electrowinning process. Therefore, for this paper, boron nitride(BN), aluminum nitride(AlN), and silicon nitride() were selected as protective and structural materials in the high temperature electrolyte. To investigate the characteristics of BN, AlN, and , in molten salts, materials were immersed in the molten salts for 24, 72, 120, and 192 hours. Also, surface condition and stability were investigated by SEM and EDS and corrosion products were calculated by HSC chemistry. As a result, among BN, AlN, and , AlN was found to show the best protective material properties.