Kinds Of Molten Salts Research Articles

Formation and Structural Characterization of Spinel‐Phase Zn2TiO4 Synthesized in a High‐Temperature Solution Approach

AbstractSpinel phase Zn2TiO4 powders were prepared by high‐temperature solution, which is a kind of molten salt (such as KCl melt). The effect of Zn2TiO4 synthesis was explored under different holding time, preparation temperature and the mass ratio of salt to raw material in KCl melt. Through experimental analysis, the synthesis temperature range of Zn2TiO4 phase in KCl molten salt system was from 800 to 1000 °C. Compared with the traditional solid‐state reaction, the stable temperature range of Zn2TiO4 phase in KCl molten salt system was wider. The HRTEM image analysis of calcined product was consistent with the XRD result. The TEM analysis showed that the average particle size of Zn2TiO4 powder was 200 nm. The crystallinity of Zn2TiO4 increased with increasing sintering time and Zn/Ti molar ratio. Compared with LiCl+KCl and LiCl melts, the crystallinity of Zn2TiO4 powder synthesized in KCl molten salt system was better. It is determined that the high‐temperature solution (KCl melt) can be successfully applied for large‐scale synthesis of spinel phase Zn2TiO4.

A brief review of liquid heat transfer materials used in concentrated solar power systems and thermal energy storage devices of concentrated solar power systems

AbstractSolar power generation is an effective approach to promote the achievement of carbon neutrality. Heat transfer materials (HTMs) are important for concentrated solar power (CSP) systems and their accessary thermal energy storage (TES) devices. The performances of HTMs can influence the operation behaviors of CSP systems and TES devices. On the whole, the HTMs can be divided into three categories according to their physical states, which are the liquid, gaseous, and solid HTMs, respectively. This article presents a brief review of research works on liquid HTMs used in CSP systems and TES devices of CSP systems, mainly including different kinds of molten salts, heat transfer oils, nanofluids, liquid metals, and water. Some typical practical applications, experimental and simulation studies on different kinds of liquid HTMs used in CSP and TES systems are introduced, and the advantages, disadvantages, and further research and development work prospects of different kinds of HTMs are briefly summarized. This article aims to providing a reference for researchers in solar thermal power field.

J2220106 凝着力計測によるイオン液体硬化過程の評価

Ionic liquid (IL) is a kind of molten salt, which has negligible vapor pressure. Therefore IL can be utilized as a support for soft materials for observation under vacuum by electron microscopy. However, it has been concerned that IL may harden by electron irradiation during the electron microscopy observation. The purpose of this study is to reveal the relations between process of IL hardening, irradiation conditions of electron beam (acceleration voltage, irradiation density) and parameter of IL such as volume of IL. Adhesion force generally has strong correlation with surface tension, which is proportional to the adhesion force. To estimate the degree of hardening, adhesion force of an individual droplet of IL was measured in scanning electron microscope (SEM) equipped with nanomanipulator. Experimental data show that the adhesion force increases for several tens minutes, and then rapidly decreases. Correlating this result with SEM images taken simultaneously, we constructed a model. At the process of a model, Surface region of IL droplet hardens rapidly and forms solid film due to high energy electron irradiation. Film gradually increases its thickness by hardening of IL near the solid/liquid interface. Simutaeously, liquid phase of IL at inner region of the droplet also hardened slowly due to electrons penetrating to inside of droplet.

Effects of Chlorate on the Hot Corrosion Behaviors of Cr0.82Al0.18N Coating Deposited on a Ti3Al Based Alloy

Abstract Cr 0.82 Al 0.18 N coating was deposited on the surface of a Ti 3 Al base alloy by a reactive magnetron sputtering method and the hot corrosion behaviors of this coating in Na 2 SO 4 +25 wt% K 2 SO 4 and Na 2 SO 4 +25 wt% NaCl molten salt were investigated. XRD and SEM were used to analyze the phase constituents and the morphologies of the corrosion products. The results show that the sample loses its mass when corroded in sulfate and chlorate mixture molten salts while the mass increases when corroded in sulfate molten salt and the corrosion products formed in both two kinds of molten salts are mainly composed of Cr 2 O 3 and θ-Al 2 O 3 . The mass loss of the sample tested in sulfate and chlorate mixture molten salts can be explained by the easy evaporation of the chlorate molten salt and the corrosion products. The accelerated dissolution of Cr 2 O 3 oxide scale will occur in the chlorate containing molten salt owing to the increase of the oxygen ion activity by the reaction between water vapor in the air and gas chlorine formed during the hot corrosion process. The gas chlorine will also react with the coating to form volatility metal chlorides to increase the consumption of the coating.

Fabrication of SrTiO3 exposing characteristic facets using molten salt flux and improvement of photocatalytic activity for water splitting

Flux treatment using various molten salts was performed for SrTiO3 powders. Morphology of SrTiO3 crystals obtained by the flux treatment strongly depended on the kinds of molten salts used. Large cubic crystals exposing {100} facets with a size of 5–6 μm were obtained by the flux treatment with LiCl whereas truncated cubes exposing {100} and {110} facets with a size of 200–400 nm were obtained when NaCl or SrCl2 was used as a flux reagent. In contrast, the flux treatment with KCl gave characteristic shaped crystals with a size of 300 nm. Electron microscope observation and electron diffraction analysis revealed that the crystals treated with the KCl flux expose {100}, {120}, and {121} facets. SrTiO3 treated with the KCl flux exhibited higher activity by 20 times than the non-flux-treated sample. Thus, a remarkable improvement of activity has been achieved by the fabrication of SrTiO3 crystals exposing high-index facets, {120} and {121}, using the KCl flux.

Design of new molten salt thermal energy storage material for solar thermal power plant

In order to obtain molten salt with lower melting point, higher thermal stability and reduced cost relative to previously available materials, a variety of molten salt mixtures of alkali nitrates are investigated by experimental methods. However, since measurements are generally expensive and time-consuming, it is of interest to be able to predict melting point and the component of multi-component systems by using the numerical methods. In this paper, eutectic point and component of a new kind of the quaternary reciprocal system (K, Na/NO2, Cl, NO3) are determined firstly by conformal ionic solution theory. Then thermal stability of the mixtures that show a lower melting point is measured by thermogravimetric analysis device. Experimental results show the agreement between measurements and calculations is found to be very good. This kind of molten salt has a lower melting point, 140°C. It is thermally stable at temperatures up to 500°C, and may be used up to 550°C for short periods. Besides, this molten salt has a reduced cost relative to previous low-melting nitrate mixtures due to the elimination of cesium nitrate and lithium nitrate.

Investigation on forced convective heat transfer of molten salts in circular tubes

In this paper, experiments are carried out to obtain convective heat transfer coefficients of turbulent flow and transition flow of molten Hitec salts in a circular tube. The present experimental data together with experimental data of four kinds of molten salts from the existing literature are correlated for transitional and turbulent convective flow respectively. In addition, the Prandtl number dependence of convective heat transfer with different working fluids is examined. It is shown that the present experimental data are in good agreement with existing correlations.

Electrochemical reduction of uranium oxide in molten fluoride mixture

A method of producing uranium metal from its oxide by a pyrometallurgical process was examined. The present method involves electrolytic reduction of dissolved uranium oxide in a molten fluoride mixture and has the characteristic that uranium oxide is electrolyzed at a high temperature above the melting point of the metal product. The possibilities for and efficiency of electrowinning are discussed for this reduction method. Electrolysis was performed at 1200 °C in two kinds of molten salts containing uranium oxide: one composition is 65 wt.% BaF 2-10LiF-25UF 4 as type A and the other is 45.5 wt.% BaF 2-19.5CaF 2-10LiF-25UF 4 as type B. High purity uranium metal was electrowon in molten salts of both types A and B. The metals coalescence and current efficiency for electrolysis in molten salt B were superior to those in molten salt A. In addition, it was found that current efficiency was poor for this method, because the metal product was dissolved by the reaction 3UF 4 + U → 4UF 3.

Evaporation of a liquid drop dropped onto a hot liquid surface. 3rd report Evaporation behavior on molten salts.

A drop of low temperature liquids such as water, methyl alcohol, etc. is dropped onto several kinds of molten salts, molten tin and glycerine over a wide range of temperature differences. The evaporation mode of the drop is roughly classified into four types. The evaporation time curve is generally of the from of an S laid sideways, similar to the curve for a solid surface, that is, the existence of maximum and minimum evaporation time points are observed. With respect to the Leidenfrost temperature, the interface temperature at the Leidenfrost point shown to be nearly equal to the limit of superheat, independent of the critical temperature. A series of precise observation shows that the splash phenomenon does not occur on molten salts, but does occur on molten tin.

Hydrocracking of coal extracts over ZnCl2-containing molten salts.

The hydrocracking of coal extracts was performed using as catalysts (in the same weight as the extract used) three kinds of molten salts, ZnCl2, ZnCl2-CuCl (3:2mol), and ZnCl2-KCl (3:2mol) at 350°C under the initial hydrogen pressure of 100kg/cm2 for 3hr. The ZnCl2-KCl system was found to be the most satisfactory for achieving the highest yields of hexanesoluble fractions and suppressing the production of undesirable gases and benzene-insoluble fractions. The maximum yield of hexane soluble was obtained when the mol per cent of KCl was 20-40. Analyses of the resulting hexane solubles indicated that the oxygen percentage, fa, and the molecular weight decreased in the order: ZnCl2-KCl (4:6mol>5:5>6:4> 7:3>8:2)>ZnCl2>ZnCl2-CuCl. These findings could be rationalized in terms of the acid strengths of the molten salts. Further characterization of hexane solubles was made by using adsorption chromatography on Floridil which gives the oil and resin fractions. The elemental analyses of resin fractions coupled with their i.r. measurements showed that the increasing amount of ZnCl2 in the ZnCl2-KCl system could bring about the progressive deoxygenation reactions of hexane solubles. The hydrocracking of each extract from Big Ben coal and Indian Ridge coal was also undertaken; these results were compared with those of Taiheiyo coal extracts based on the average molecular structure of each extract deduced by using a computer-assisted method.

粗バナジウム，V<SUB>2</SUB>C，およびVCを陽極材とするバナジウムの電解製造について

The cathodic deposition of vanadium was investigated using the V-C-O alloys (crude vanadium, V2C and VC) produced by carbothermic reduction as the anode materials, and two kinds of molten salts, KCl(44)-NaCl(44)-NaF(7)-K2NaVF6 (5 mol%) and KF(62)-NaF(33)-K2NaVF6 (5 mol%), as the electrolytes. The cathode current efficiency depended strongly on the anode current density and little on the cathode current density. Initial anode current densities more than 200 A/m2 was necessary to obtain high cathode current efficiencies. It was found that crude vanadium (C: 0.45∼1.27, O: 0.66∼3.66 wt%) is more suitable for the anode material than V2C and VC, and the KCl-NaCl-NaF-K2NaVF6 molten salt is more appropriate for the electrolyte than the KF-NaF-K2NaVF6 molten salt. Without special purification of the bath, pure vanadium which contained oxygen ranging from 1600 to 3000 ppm and carbon ranging from 90 to 270 ppm was easily obtained from the crude vanadium (C: 0.45∼1.27, O: 0.66∼3.66 wt%) in the KCl-NaCl-NaF-K2NaVF6 bath under the electrolytic conditions of the initial anode current densities of 210 to 290 A/m2, the initial cathode current density of 10000 A/m2, and the bath temperature of 725°C. The microvickers hardness number of vanadium obtained ranged from 159 to 220 (1 kg-load). Eighty-five percent of vanadium in the crude vanadium was recovered at the cathode.