•TiC reinforced Ni based composite has been prepared in molten salt.•The composite comprises aggregated Ni-TiC particles and dissociative TiC particles.•The composite particles present a multicore-rim structure.•Ni acts a catalyst to accelerate the formation of TiC.•Formation of CaTiO3 is evaluated in terms of thermodynamics.Ni-TiC composite powder was synthesized from a NiO/TiO2/C mixture by a joint process of chemical reduction in argon atmosphere, electrochemical reduction of TiO2 and subsequent carbonization of the reduced Ti in molten salt. The reduction was investigated by terminating the electrochemical experiments for various durations, as well as comparing with the results for direct electro-deoxidation of NiTi alloys from a NiO/TiO2 mixture. The results showed that the product consisted of aggregated Ni-TiC composite particles about 1 μm and dissociative TiC particles about 100 nm. The composite particles owned a multicore-rim structure composed of approximately dispersed TiC particles in the Ni matrix. The formation of intermediates, such as CaTiO3, Ni3Ti and NiTi, was evaluated from the viewpoint of thermodynamics. Ni acted as a catalyst via generation and subsequent decomposition of Ni-Ti alloys. Carbon powder undertook a reducing agent for NiO in the sintering process as well as a reactant during carbonization of Ni-Ti alloys in molten salt. The introduction of Ni and C into the precursor accelerated the reduction by the chemical driving force derived from reactions between Ni, Ti and carbon.

•The redox mechanism of zirconium in a fluoride salt system was investigated.•A multi-step redox process of Zr was found with various electrochemical methods.•Perspectives on zirconium electro-refining process were proposed.In the present paper, a detailed study of the redox behavior of zirconium in the eutectic LiF-NaF system was carried out on an inert molybdenum electrode at 750 °C. Several transient electrochemical methods were used such as cyclic voltammetry, square wave voltammetry, chronopotentiometry, and open circuit voltammetry. The reduction of Zr (IV) was found to follow a two-step mechanism of Zr (IV)/Zr (II) and Zr (II)/Zr at the potentials of about −1.10 and −1.50 V versus Pt, respectively. The theoretical evaluations of the number of transferred electrons according to both cyclic voltammetry and square wave voltammetry further confirmed the Zr reduction mechanism. The estimations of Zr (IV) diffusion coefficient in the LiF-NaF eutectic melt at 750 °C through cyclic voltammetry and chronopotentiometry are in fair agreement, as to be approximately 1.13E-5 and 2.42E-5 cm2/s, respectively.

ZrC/ZrSi nanocomposite powders are in situ synthesized from ZrSiO4 and carbon through a one-pot electrochemical process. The pathway from the precursor of ZrSiO4/carbon to ZrC/ZrSi composites is investigated by time-dependent electrochemical reduction experiments. The results show that the composite powder involving nano-sized ZrC particles dispersed inside the ZrSi matrix is fabricated through an electrochemical route. The ratio of ceramic phases to metallic phases in the final products can be controlled by adjusting the amount of carbon in the original materials. The electrochemical route in molten salt provides a feasible method for in situ preparation of nano-sized ZrC/ZrSi composite powders at relatively lower temperature.

NbC–Sn composite powder was successfully prepared from SnO2, Nb2O5 and carbon by electrochemical reduction and carbonization in CaCl2–NaCl molten salt at 900 °C. The reaction pathway was investigated by terminating electrochemical experiments for various durations. The influence of carbon on the final products was considered. NbC particles were obtained by leaching the composite with acid. The results showed that the aggregated NbC–Sn composite powdev contained NbC particles about 50–100 nm and Sn particles about 200 nm. SnO2 was reduced to Sn in the sintering process. Nb2O5 was electrochemically reduced to Nb in molten salt, experiencing some intermediate products of calcium niobates and niobium suboxides. Nb metal obtained was converted to NbC with assistance of carbon. The reduction of Nb oxides may be incomplete and Nb3Sn would be formed if carbon is insufficient in the cathodic pellet. NbC with good dispersity is produced by leaching NbC–Sn with HCl.

•Carbon film was prepared by anodic deposition in molten salt.•A mixture of sp3 and sp2 with graphite and amorphous carbon phases was obtained.•Two-stage potentiostatic deposition enables to form solid solution.•This method can be extended to other metal substrate which can dissolve carbon.The electrochemical deposition of carbon films on a nickel substrate was carried out through anodic oxidation of calcium acetylide dissolved in a LiCl–KCl–CaCl2 melt at 823 K. Continuous and tenacious carbon films were prepared by a two-stage anodically potentiostatic deposition at a fast rate, and characterized by SEM, Raman spectroscopy, XRD and XPS. The results show the carbon films composed of micron-sized particles with graphitized and amorphous phases containing a mixture of sp3 and sp2 carbon. The cyclic voltammetry behavior of acetylide anion on graphite and nickel electrodes indicated that C22 − ions are oxidized more favorably on the nickel substrate due to the anodic depolarization from nickel carburization.

The solubility of 1,3,5-benzenetricarboxylic acid in pure water, isopropyl alcohol, isobutyl alcohol, methanol, ethanol, and ethylene glycol were measured at the temperature range from 298 to 360 K. The order of solubility of 1,3,5-benzenetricarboxylic acid was ethanol > methanol > ethylene glycol > isobutanol > isopropyl alcohol > water. In addition, the Apelblat equation was used to correlate the solubility with temperature in different solvents.

We report Seebeck coefficients of electrochemical cells with molten carbonate mixtures as electrolytes and carbon dioxide|oxygen electrodes. The system is relevant for use of waste heat and off-gases with concentration of carbon dioxide different from air, as for example in the metallurgical industry. The coefficient is −1.25 mV K−1 for a nearly equimolar mixture of lithium and sodium carbonate with dispersed magnesium oxide at 750 °C, one bar total pressure and a pressure ratio of carbon dioxide to oxygen of 2:1. The value is slightly lower when sodium is replaced by potassium. The theoretical expression of the Seebeck coefficient was established using the theory of non-equilibrium thermodynamics. We used this expression to predict an increase to −1.4 mV K−1 when lowering the gas partial pressures to 0.015 and 0.2 bar, respectively, for carbon dioxide and oxygen, a gas composition that can represent that of the off-gases from a silicon furnace which we are concerned with. The absolute value of the Seebeck coefficient increases by 0.2 mV K−1 when the cell average temperature increases from 550 to 850 °C. The presence of a second component in the electrolyte increases the coefficient significantly above the values obtained with one component, compatible with a lowering of the transported entropy of the carbonate ion. A concentration cell, using the off-gas from the silicon furnace as anode gas and air as cathode gas, will add 0.14 V at 550°C to the absolute value of the potential. The series construction has the potential to offer a power density at matched load conditions in the order of 0.5 kW m−2.

The Seebeck coefficient is reported for thermoelectric cells with gas electrodes and a molten electrolyte of one salt, lithium carbonate, at an average temperature of 750 °C. We show that the coefficient, which is 0.88 mV K−1, can be further increased by adding an inorganic oxide powder to the electrolyte. We interpret the measurements using the theory of irreversible thermodynamics and find that the increase in the Seebeck coefficient is due to a reduction in the transported entropy of the carbonate ion when adding solid particles to the alkali carbonate. Oxides of magnesium, cerium and lithium aluminate lead to a reduction in the transported entropy from 232 ± 12 to around 200 ± 4 J K−1 mol−1. This is of importance for design of thermoelectric converters.

TiC reinforced Fe based composite powder was electrochemically prepared directly from titanium-rich slag and carbon in molten CaCl2–NaCl at 800 °C. The reaction pathway from the slag and carbon to TiC–Fe based composite powder was investigated by examination of partially and fully reduced samples using XRD and SEM with EDS analyses. The process of reduction and the carbiding process can be divided into the two main stages. The first stage of the process is electrochemical reduction, while the second stage is a synergetic reaction of electrochemical de-oxidation and carbiding. During the second stage, TiC forms from TiCxO1−x, in which the carbon atoms substitute for oxygen atoms successively to give stoichiometric TiC. The TiC grains initiate the heterogeneous nucleation of the TiC–Fe based alloy particles with a multi-core microstructure.