Showing papers on "Molten salt published in 2008"
TL;DR: In this paper, a short overview of silicate glass strengthening by exchange of alkali ions in a molten salt, below the glass transition temperature (chemical tempering), is presented, along with the simplified modelling of the stress build-up.
Abstract: This paper presents a short overview of silicate glass strengthening by exchange of alkali ions in a molten salt, below the glass transition temperature (chemical tempering). The physics of alkali inter-diffusion is briefly explained and the main parameters of the process, which control the glass reinforcement, are reviewed. Methods for characterizing the obtained residual stress state and the strengthening are described, along with the simplified modelling of the stress build-up. The fragmentation of chemically tempered glass is discussed. The concept of engineered stress profile glass is presented, and finally, the effect of glass and salt compositions is overviewed.
300 citations
TL;DR: In this article, an overview of the important properties and design characteristics of electrolyte used in thermally activated (thermal) batteries is given. But, the authors do not discuss the physical properties of the electrolytes used in thermal batteries.
217 citations
01 Jan 2008
TL;DR: In this article, the authors report the development of multi-component molten salt formulations consisting of common alkali nitrate and alkaline earth nitrate salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems.
Abstract: Thermal energy storage can enhance the utility of parabolic trough solar power plants by providing the ability to match electrical output to peak demand periods. An important component of thermal energy storage system optimization is selecting the working fluid used as the storage media and/or heat transfer fluid. Large quantities of the working fluid are required for power plants at the scale of 100-MW, so maximizing heat transfer fluid performance while minimizing material cost is important. This paper reports recent developments of multi-component molten salt formulations consisting of common alkali nitrate and alkaline earth nitrate salts that have advantageous properties for applications as heat transfer fluids in parabolic trough systems. A primary disadvantage of molten salt heat transfer fluids is relatively high freeze-onset temperature compared to organic heat transfer oil. Experimental results are reported for formulations of inorganic molten salt mixtures that display freeze-onset temperatures below 100°C. In addition to phase-change behavior, several properties of these molten salts that significantly affect their suitability as thermal energy storage fluids were evaluated, including chemical stability and viscosity. These alternative molten salts have demonstrated chemical stability in the presence of air up to approximately 500°C in laboratory testing and display chemical equilibrium behavior similar to Solar Salt. The capability to operate at temperatures up to 500°C may allow an increase in maximum temperature operating capability vs. organic fluids in existing trough systems and will enable increased power cycle efficiency. Experimental measurements of viscosity were performed from near the freeze-onset temperature to about 200°C. Viscosities can exceed 100 cP at the lowest temperature but are less than 10 cP in the primary temperature range at which the mixtures would be used in a thermal energy storage system. Quantitative cost figures of constituent salts and blends are not currently available, although, these molten salt mixtures are expected to be inexpensive compared to synthetic organic heat transfer fluids. Experiments are in progress to confirm that the corrosion behavior of readily available alloys is satisfactory for long-term use.
181 citations
TL;DR: In this article, the synthesis of a novel nanostructure of LiCoO{sub 2, and its performance as a cathode for a high-rate lithium ion battery, is described.
Abstract: The synthesis of a novel nanostructure of LiCoO{sub 2}, and its performance as a cathode for a high-rate lithium ion battery, is described. The LiCoO{sub 2} nanostructure resembles the morphology of a known natural mineral: 'desert rose' gypsum. A range of measurement techniques are used to investigate the growth mechanism of this structure and the origin of its high rate charge/discharge properties.
153 citations
TL;DR: In this article, a flake-like nanoscale γ-bismuth molybdate (Bi2MoO6) powders as a novel photocatalyst was prepared using a simple low-temperature molten salt method at 350°C for 1, 4 and 8h, respectively.
101 citations
TL;DR: In this paper, phase diagrams of binary mixtures of bis(trifluoromethylsulfonyl) amides have been constructed, and their eutectic compositions and temperatures have been determined.
Abstract: Phase diagrams of binary mixtures of alkali bis(trifluoromethylsulfonyl)amides have been constructed, and their eutectic compositions and temperatures have been determined. It has been revealed that the molten salt electrolytes having the melting points in the intermediate temperature range (373 to 473) K are easily formed by simple mixing of two kinds of single alkali bis(trifluoromethylsulfonyl)amide salts. The 1:1 or 3:1 double salt is occasionally formed for some binary systems.
100 citations
TL;DR: The ability to calculate activity coefficient ratios using molecular dynamics simulations with sufficient precision to guide the choice of suitable solvent systems in practical applications is demonstrated.
Abstract: The ability to separate fission products by electrodeposition from molten salts depends, in part, on differences between the interactions of the different fission product cations with the ions present in the molten salt "solvent". These differences may be expressed as ratios of activity coefficients, which depend on the identity of the solvent and other factors. Here, we demonstrate the ability to calculate these activity coefficient ratios using molecular dynamics simulations with sufficient precision to guide the choice of suitable solvent systems in practical applications. We use polarizable ion interaction potentials which have previously been shown to give excellent agreement with structural, transport, and spectroscopic information of the molten salts, and the activity coefficients calculated in this work agree well with experimental data. The activity coefficients are shown to vary systematically with cation size for a set of trivalent cations.
96 citations
TL;DR: In this paper, a method for preparing protective titanium carbide (TiC) coatings on carbon fibres has been developed using a molten salt synthesis method using a mixture of molten LiCl−KClCl-KF salts under an argon atmosphere at 900 and 950 degrees C. The coating thickness was closely related to the composition of the molten salts and to the molar ratio between the carbon fibre and titanium.
92 citations
TL;DR: In this article, a numerical tool for thermal-fluid-dynamic simulation of circuits, with such a mixture as the primary heat transfer fluid, was pursued and the RELAP5 code was modified accordingly.
88 citations
TL;DR: In this article, Binary phase diagrams of LiFSI and NaFSI-KFSI systems have been constructed, and the electrochemical window of the eutectic Li FSI KFSI is as wide as 6.0 V at 348 K with the cathode limit being lithium metal deposition.
88 citations
TL;DR: In this article, the authors focused on thermal stability of multi-component molten salt consisting of potassium nitrate, sodium nitrite, sodium ammonium, and sodium nitrate and one kind of additives such as A, B and C at a high temperature.
Abstract: This paper focuses on thermal stability of molten salts consisting of potassium nitrate, sodium nitrite, sodium nitrate and one kind of additives such as A, B and C at a high temperature. The multi-component molten salts were prepared by mixing the pure salts, heating statically to the melting state and then cooling to room temperature to form the mixed molten salts. The stability experiments were carried out at 500 and 550°C, and the experiment found that the molten salt with 5% additive A performed better high-temperature thermal stability and its optimum operating temperature was increased to 550 from 500°C. XRD and DSC analyses indicated that the molten salt with 5% additive A had a lower freezing point and a higher phase change latent heat. Besides, the concentration of NO 2 anion in the molten salt was analyzed and the results showed that the main reaction for the molten salts in air was nitrite thermal oxidation at 500 and 550°C. In addition, the energy used for the oxidation of nitrite would be increased with an increase in additives and the prolonging of reaction time at the same time.
TL;DR: In this paper, the surface tension of a ternary carbonate mixture can be predicted from known surface tension for binary carbonates, and the mixing of two molten carbonate mixtures of the same surface tension makes a mixture of almost equal surface tension before mixing in this ternsary system.
Abstract: The density, surface tension, and electrical conductivity of the ternary molten salt mixtures of Li 2 CO 3 -Na 2 CO 3 -K 2 CO 3 system have been measured. The molar volumes of the ternary mixtures agreed well with those estimated by additivity arguments within 0.7%. It was found that the surface tension of a ternary carbonate mixture can be predicted from known surface tension of binary carbonates, and the mixing of two molten carbonate mixtures of the same surface tension makes a mixture of almost equal surface tension before mixing in this ternary system. We have succeeded in predicting the equivalent conductivity of the ternary carbonate mixtures using the cationic radii and the equivalent conductivities of the pure carbonates.
TL;DR: The utilization of concentrated solar energy as external heat source for methane steam reforming has been investigated in this paper, where Molten salts at temperatures up to 550°C can be used as solar heat carrier and storage system, and hydrogen selective membranes can also be used to drive reforming reaction at lower temperatures than conventional (<550°C), with hydrogen purification achieved thereby.
Abstract: The utilization of concentrated solar energy as external heat source for methane steam reforming has been investigated. Molten salts at temperatures up to 550°C can be used as solar heat carrier and storage system, and hydrogen selective membranes can be used to drive reforming reaction at lower temperatures than conventional (<550°C), with hydrogen purification achieved thereby. The combination of new technologies such as membranes and membrane reactors, concentrating solar power (CSP) systems, and molten salt heat carriers, allows a partial decarbonation of the fossil fuel together with the possibility to carry solar energy in the current natural gas grid. Different plant configurations and operating conditions have been analyzed using a mathematical model and AspenPlus simulator. © 2008 American Institute of Chemical Engineers AIChE J, 2008
TL;DR: In this article, a series of spinel Li4Ti5O12 samples were synthesized via a composite molten-salt method (CMSM) using the mixtures of LiCl and KCl with different L values as the reaction media.
TL;DR: In this article, the electrochemical behavior of terbium at a tungsten electrode, in the eutectic LiCl-KCl molten was investigated by means of cyclic voltammetry, chronopotentiometry and chronoamperometry.
TL;DR: In this article, the electrodeposition of nickel and nickel-zinc alloys was investigated at polycrystalline tungsten electrode in the zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt.
TL;DR: In this paper, semi-crystalline potassium titanates, useful as precursors to produce composite materials and coatings, were synthesized by thermal treatment of powdered TiO2 in molten mixtures of KNO3 and KOH at 4501-5501C.
Abstract: Semi-crystalline potassium titanates, useful as precursors to produce composite materials and coatings, were synthesized by thermal treatment of powdered TiO2 in molten mixtures of KNO3 and KOH at 4501–5501C. The products obtained had similar structures of laminar crystals, aggregated in particles of about 3 l mo fn 5 TiO2/K2O molar ratio in the range 2.8– 6.0. The value of n could be regulated by the temperature of synthesis, the weight ratio of [KOH]/[KNO3] in the molten salt mixture, and the number of water washing operations. The reduction of the TiO2/K2O molar ratio increased the contents of H2O in the composition of potassium polytitanate, from 5.3 to 11.4 and from 0.2 to 8.6 (wt%) in the adsorbed and structural forms. The thermal treatment of the potassium polytitanate precursors obtained resulted in dehydration and chemical interaction with unreacted TiO2 at 5001–7501C, amorphization at 7501–8501C, crystallization of K2Ti4O9 (in some cases K3Ti8O17 )a t 8501–10901C, and crystallization of K2Ti6O13 at temperatures 410901C. The mechanisms of the structural transformation and phase evolution were considered as a function of the TiO2/K2O molar ratio in the potassium polytitanate.
TL;DR: In this article, samples of AZ91D magnesium alloy were dipped into AlCl 3 NaCl molten salt at different temperatures between 250°C and 400°C for 28800 s. The coating was mainly composed of Al 12 Mg 17 and Al 3 Mg 2 intermetallic compounds.
TL;DR: In this paper, the (1 − 1 − 0)-layered perovskite La2Ti2O7 photocatalyst has been synthesized in high purities and in homogeneous microstructures within a molten Na2SO4/K 2SO4 flux in short reaction times of ∼1 − 10h.
Abstract: The (1 1 0)-layered perovskite La2Ti2O7 photocatalyst has been synthesized in high purities and in homogeneous microstructures within a molten Na2SO4/K2SO4 flux in short reaction times of ∼1–10 h. The La2Ti2O7 particle morphologies and sizes were investigated as a function of flux amounts (flux:La2Ti2O7 molar ratios of 1:1, 2:1, 5:1, and 10:1) and reaction times (1, 2, 5, and 10 h). Powder X-ray diffraction confirmed the structure type and high purity, and UV–vis diffuse reflectance measurements yielded optical bandgap sizes of ∼3.75–3.81 eV. Rectangular platelet morphologies are obtained with maximal dimensions of ∼500–5000 nm, but with thicknesses down to
TL;DR: In this article, nano and submicrometer scale titanium oxide (TiO 2 ) powders were synthesized by solid and molten salt synthesis (SSS and MSS) from amorphous titanium hydroxide precipitate.
Abstract: Nano and submicrometer scale titanium oxide (TiO 2 ) powders were synthesized by solid and molten salt synthesis (SSS and MSS) from amorphous titanium hydroxide precipitate. Sodium chloride (NaCI) and dibasic sodium phosphate (Na 2 H-PO 4 ·2H 2 O, DSP) separately or as mixture with different weight ratios were used as the salts. At the eutectic salt composition (20% DSP/80% NaCI), the microstructure and phase composition of the TiO 2 was changed from equiaxed nanoparticles of anatase with size ∼40-50 nm, to mixed microstructure of bundle and acicular particles of rutile with 0.05-0.2 μm diameter, 6-10 μm length, and aspect ratio 20-60 depending on treatment time and temperature. At high temperature (825°C) and long time (30 h), microstructural differences were significant for the powders treated with different salts. Particle morphologies ranged from equiaxed, to acicular, to bundles, to nanofibers with very high aspect ratio. At lower treatment temperature (725°C) for shorter time (3 h), the morphology of the products did not change with different salt compositions, but the crystallite sizes changed appreciably. Different starting titanium precursors influenced particle size at lower temperature and time. Titanium hydroxide heat treated without salt resulted in significant grain growth and fused secondary particles, as compared with more finely separated and lightly agglomerated powders resulting from SSS and MSS treatments.
TL;DR: Titanium carbide (TiC)-coated graphite for refractory castable applications was prepared via reacting titanium metal powder (∼45 μm) and natural graphite flakes (100-300 μm), for 5 h at 950°C in a KCl-based salt in the Ar atmosphere as mentioned in this paper.
Abstract: Titanium carbide (TiC)-coated graphite for refractory castable applications was prepared via reacting titanium metal powder (∼45 μm) and natural graphite flakes (100–300 μm) for 5 h at 950°C in a KCl-based salt in Ar atmosphere. TiC coatings formed on graphite flakes were uniform, crack-free, and composed of nanosized particles (20–40 nm). The “template-growth” mechanism played a dominant role in the coating formation process.
TL;DR: In this paper, the gas-sensing properties of spinel zinc ferrite nanoparticles were investigated for ethanol, LPG, H2, NOx, SOx, and H2S.
Abstract: Zinc ferrite (ZnFe2O4) nanoparticles have been synthesized at 700°C using sodium chloride as a growth inhibitor. Single-phase formation of spinel zinc ferrite having crystallite size in the range of 15–20 nm was observed by XRD and confirmed by TEM. In the present work, the gas-sensing properties of these zinc ferrite nanoparticles toward ethanol, LPG, H2, NOx. SOx, and H2S have been studied. It was found that they exhibit excellent selective sensitivity toward 200 ppm of H2S at the operating temperature of 250°C, and thus this nanosized ferrite is expected to be useful in an industrial application as a potential H2S gas sensor.
TL;DR: In this article, the physicochemical properties of a new rechargeable lithium battery operating at intermediate temperature (100-180°C) were studied to develop a rechargeable battery operating with a constant current rate of C/10.
TL;DR: A high-yield synthesis of SnO(2) nanoparticles via a facile, economical and easily scalable solid-state molten salt synthesis method has been demonstrated and Hydrogen sensors made from the SnO('s2') nanoparticles were found to possess high sensitivity and stability.
Abstract: A high-yield synthesis of SnO2 nanoparticles via a facile, economical and easily scalable solid-state molten salt synthesis method has been demonstrated. The inorganic additive, molar ratios of chemicals and annealing temperature were found to control the size and porosity of the SnO2 nanoparticles. The synthesized SnO2 nanostructures were uniform, well dispersed and exhibited high crystallinity. Hydrogen sensors made from the SnO2 nanoparticles were found to possess high sensitivity and stability. Other than tailoring the material's structure in terms of size and porosity, another potential method of enhancing the gas sensitivity is functionalization with noble Pd metal.
TL;DR: It was shown that NaCl reacted with BaO (PbO) resulting in loss of volatile BaCl2 (P bCl2) and formation and preferential growth of titanium oxide-rich nanorods instead of the target phase BaTiO3 (or Pb TiO3).
Abstract: A molten salt synthesis route, previously reported to yield BaTiO3, PbTiO3, and Na2Ti6O13 nanorods, has been re-examined to elucidate the role of volatile chlorides. A precursor mixture containing barium (or lead) and titanium was annealed in the presence of NaCl at 760 or 820 °C. The main products were respectively isometric nanocrystalline BaTiO3 and PbTiO3. Nanorods were also detected, but electron diffraction revealed that the composition of the nanorods was respectively BaTi2O5/BaTi5O11 and Na2Ti6O13 for the two different systems, in contradiction to the previous studies. It was shown that NaCl reacted with BaO (PbO) resulting in loss of volatile BaCl2 (PbCl2) and formation and preferential growth of titanium oxide-rich nanorods instead of the target phase BaTiO3 (or PbTiO3). The molten salt synthesis route may therefore not necessarily yield nanorods of the target ternary oxide as reported previously. In addition, the importance of NaCl(g) for the growth of nanorods below the melting point of NaCl w...
TL;DR: In this paper, yttria-stabilized zirconia coatings of 300μm were applied over type 316L stainless steel with a metallic bond coating of 50μm by an optimized plasma spray process, and were assessed for the corrosion behaviour in molten LiCl-KCl medium at 873 K for periods of 5h, 100h, 250h and 500h.
TL;DR: In this paper, the authors measured the solubility of equimolar molten salt CaCl2-x (x = 0, NaCl, KCl, SrCl2, BaCl2 and LiCl) at 873-1223 K and activity coefficient calculated.
TL;DR: In this article, the authors examined selected design issues associated with reactor scale-up in the thermochemical copper-chlorine (Cu-Cl) cycle of hydrogen production, focusing on the hydrogen, oxygen and hydrolysis reactors.
TL;DR: In this article, the electrochemical study of Yb(III) ions in molten alkali metal chlorides in the temperature range 723 −1073 K was presented, and it was shown that the reduction reaction YbCl 2 ǫ+1/2Cl 2ǫ=YbCl 3 is reversible being controlled by the rate of the mass transfer.
TL;DR: The system investigated was modeled by the restricted primitive model of electrolyte being in contact with the charged hard wall and showed a multilayer structure of the electrolyte in the vicinity of the electrode surface, which depended on the electrode charge, but not much on temperature.
Abstract: Results of the Monte Carlo simulation of the electrode/molten salt interface are reported. The system investigated was modeled by the restricted primitive model of electrolyte being in contact with the charged hard wall (hard spheres of diameter d=400pm and relative permittivity er=10). The temperature analysis of the mean activity coefficient γ±, heat capacity Cv and radial distribution function, g, indicated the range of temperatures of the study. Calculations for the electrode/electrolyte interface were carried out for temperatures 1300, 1400, and 1500K and in the range of the electrode charge densities σ from 0.025to0.5Cm−2. Singlet distribution functions showed a multilayer structure of the electrolyte in the vicinity of the electrode surface. The structure depended on the electrode charge, but not much on temperature. The capacitance curves had a parabolalike shape with the maximum located at σ=0. This result is not consistent with the Gouy–Chapman theory, but has been confirmed by the modified Pois...