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Chlorination of zirconium compounds Filatov A.A. This paper examines the main methods of chlorination of natural zirconium com- pounds, evaluates the efficiency of existing technologies and considers the most prom- ising methods for the development of the industry. Currently, research and develop- ment of new, energy-efficient methods for processing zirconium-containing natural compounds and man-made waste are being actively carried out throughout the world. The existing hydrometallurgical methods for processing zirconium-containing materials have a number of significant disadvantages, such as: multi-stage nature, low degree and intensity of zirconium extraction, high consumption of reagents, or the need for long-term disposal in the case of processing nuclear waste. The most promising from a technical and economic point of view are pyrochemical methods of processing zirconium in molten salts due to the greater intensity of the process and the possibility of utilizing a wider range of compounds. Chlorine metallurgy methods are the basis for the production of most rare earth elements, and for elements such as titanium, zirconium, and hafnium, there are no acceptable alternatives and are the only way to obtain high-purity metal. Most often, chlorination is carried out in melts based on chlorides of alkali and alkaline earth metals, within 1000 °C. Chlorination of oxides with pure chlorine, without the use of a reducing agent, is impossible up to a temperature of 827 °C and higher, due to the positive values of the Gibbs energy of the reaction, therefore, reducing agents are used to carry out the process, in particular various forms of carbon, however, this method makes it difficult to maintain the stoichiometry of the loaded reagents, which leads to the accumulation of carbon in the reaction zone. The main obstacles to the development of the idea of using carbon tetrachloride were its high cost, toxicity, and limited solubility in salt melts, which makes it more suitable for direct chlorination of oxides in CCl4 vapors. Chlorination using elemental sulfur as a reducing agent seems more promising in terms of energy costs, technological effectiveness, and overall process efficiency. To increase the efficiency of chlorination, it is possible to use a combined method using a chlorine-carbon-sulfur system. The proposed method allows to reduce the process temperature and synthesize the necessary compounds directly in the reactor, which will reduce the number of technological operations and increase the profitability of the process.
Keywords: zirconium, oxide, chlorides, chlorination, processing, recovery, melt DOI: 10.31857/S0235010625020019
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2025;(2):89-99 | |
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Selection of the optimal composition of plasma coating of the Ni-B-Si system by the CALPHAD methods Bakhteev I.S., Oleinik K.I., Litvinyuk K.S., Furman E.L., Valiev R.M. Copper and alloys are widely used in parts of metallurgical equipment. Due to high heat capacity and reflectivity of IR radiation, copper parts have found application in water- cooled blast furnace elements, such as tuyeres, which are subject to active gas-abrasive, erosive and other types of wear and gas corrosion. Copper and its alloys have low resistance to wear and corrosion. To increase the resistance of copper parts, thermal barrier coatings of the Ni–B–Si, Ni–Cr–Al–Y and ZrO2 systems are offered. However, the first layers of the coating have low adhesion, and consequently, low strength of the first and subsequent layers. Laser remelting solves the problem of adhesion of the first layer to copper and the remaining layers to the fused layer. Using the CALPHAD methods in the TermoCalc software package (software version number 2024.1.132110-55), the effect of reflow on the properties of the protective coating of the Ni-B-Si system was simulated. The following composition was chosen as the base: Ni – 86.97 at.%, B – 6.93 at.%, Si – 6.1 at.%. When laser radiation is applied to a coating applied by the gas-thermal method, active interac- tion of the coating components with copper is observed, forming a continuous coating containing new phases and chemical elements. The appearance of some of these phases occasionally leads to cracking due to the formation of a stable compound of copper-nickel alloy (monel metal), which has relatively low plasticity. Using X-ray phase analysis data, it was confirmed that during the melting process, active mixing of the coating components (Ni–B–Si) with the substrate components (Cu) occurs, forming a stable compound of Cu with Ni. In this regard, using mathematical modeling, the density changes were predicted and the crystallization rates were determined using the Sheil method, as well as the phases formed during cooling in the coating, namely: Ni86.97-B6.93-Si6.1, Ni84.47-Cu2.5-B6.93-Si6.1, Ni81.97Cu5B6.93Si6.1, Ni76.97Cu10B6.93Si6.1, Ni71.97Cu15B6.93Si6.1, Ni66.97Cu20B6.93Si6.1. Using calculation methods, based on the provisions of thermodynamics, the process of laser melting is described during heating from 1750 K to 3000 K and subsequent cooling from 1750 K to 500 K. When studying the melting process, for all compositions it was deter- mined that a copper content in the coating of about 15-20 at.% is favorable for the for- mation of a good quality coating, since at these concentrations the most complete release of copper atoms from the grain boundaries occurs, their transition to the surface layers of the coating and their binding with nickel into stable compounds of the monel-metal type. Keywords: thermal spray coating, CALPHAD, TermoCalc, Cu, Ni-B-Si, laser surface melting, monel-metal, X-ray phase analysis DOI: 10.31857/S0235010625020021 |
2025;(2):100-113 | |
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Effect of oxygen on the morphology of silicon deposits Gevel T.A., Suzdaltsev A.V. DOI: 10.31857/S0235010625020038
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2025;(2):114-124 | |
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Application of the modified mixing rule components and consideration of their data for calculation of thermophysical properties of lead-potassium alloys Terekhov S.V. Alloys based on the potassium-lead system are used as liquid-metal coolants in heat-dissipating elements of fast neutron nuclear power plants. Due to the practical importance of this alloy, a semi-empirical calculation of thermophysical characteristics (heat capacity, coefficient of thermal linear expansion, density, thermal conductivity, thermal diffusivity and specific electrical resistance) of potassium, lead and melt of lead with potassium was carried out. For calculations we used the arrays of experimental data coordinated with each other, relations of the author’s model of two-phase local-equilibrium region and the modified rule of mixing of components. In the formation of thermal properties of components and their alloys give as phenomena in any small neighborhood of the sample point (local level), and collective phenomena of reac- tions of all points of the alloy (substantive level) to temperature changes. The existence of features in the temperature dependences of potassium and lead in the form of peaks, pits and jumps, as well as the inheritance of some graphical features of the temperature curves of components in the formation of thermal properties of the melt are indicated. By means of approximation of the experimental data of the melt, the disappearance of some features during the formation of the alloy was established. On experimentally unexplored temperature intervals the behavior of thermophysical characteristics of components is demonstrated, and thermal properties of the melt are displayed in the form of tables. It is pointed out the necessity of additional experimental work to verify the calculations performed and to clarify the behavior of thermophysical characteristics of the components and their alloy at unexplored temperature intervals. Keywords: potassium, lead, alloy, heat capacity, coefficient of thermal linear expansion, density, thermal conductivity, thermal diffusivity DOI: 10.31857/S0235010625020048 |
2025;(2):125-142 | |
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Study of the ternary system Cs2MoO4-MoV2O2-MoO3 and its triangulation Gasanaliev A.M. The main task of physicochemical analysis is the study of multicomponent systems. Knowledge of phase levels and their regularities in multicomponent systems is necessary for the development of optimal conditions for the search for compositions with given conditions. For this purpose, we studied the ternary system Cs2O–V2O5–MoO3. Based on the results of experimental studies, the first promising areas of the phase diagram for the synthesis of vanadium-molybdenum bronzes of cesium were obtained. Compositions obtained on the basis of the system are promising in the development of new materials, in particular: anti-corrosion coatings, ion-electronic conductors with high activity. Theoretically, based on the results of the data obtained, it was proved that the synthesis of new materials from complex oxide phases by crystallization methods from a solid-phase fusion melt can be used to break down a three-component oxide system Cs2O–V2O5–MoO3, to identify topology patterns and phase formation in them. The topological image of the phase diagram constructed by a combination of data from its faceting elements is characterized by the presence of three congruent and four incongruently melting binary compounds on the faces, which divide it into four sub- systems (I–IV), the most interesting, in our opinion, variants of triangulation of this system, according to which it was identified in triangulating sections, which divide it into 10 subsystems, which are quasi-three-component and triple systems, hence, they can be studied independently. For the convenience of performing extreme work both on the synthesis of individual compounds (D1–D3) and thermal analysis of systems, a set of methods of physical and chemical analysis was used. In particular, visual polythermic, differential thermal analysis. Finally, the main thing in this work is the prediction, modeling and experimental confirmation of phase formation in the system Cs2O–V2O5–MoO3, its stable and metastable processes, which will make it possible to maximize the mechanism of the conditions for the formation and decay of the qualitative and quantitative composition of the phases. Keywords: compound, congruent, incongruent, diagram, phase complex, projection, liquidus, model, perithectics, segment, complex, system, prognosis, polytherm, stable complex, solid solutions, subsystem, bronzes, quasibinary, crystallization DOI: 10.31857/S0235010625020054
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2025;(2):143-151 | |
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With the development of scientific and technological progress, the requirements for reliability (increased service life) of components and structural parts have changed. Machine components made from high-carbon manganese steel are subject to wear, which can lead to increased costs. It is widely known that structures consisting of steel 76, GOST 51045-97 are significantly wearing out. By modifying the surface layer using laser surfacing and subsequent melting, it becomes possible, through active mix- ing and rapid solidification that occurs during melting, not only to homogenize the structure, but also to implement hardening processes of the near-surface layers of the most loaded (vulnerable) zones. Using the CALPHAD methods in the TermoCalc software package (software version number 2024.1.132110-55), the effect of the applied protective coating (AlTiZrVNb) with subsequent melting on the change in the phase composition and distribution of elements on the outer crystalline layer of the substrate was simulated. An alloy of the composition Al31.17Ti18.55Zr1.56V27.53Nb21.19 was selected for the calculations. When laser radiation is applied to the deposited coating, active interaction of the coating components with the base metal (iron) is observed, resulting in the formation of a modified top layer containing new phases with iron in the composition. In this regard, using mathematical modeling, the Scheil method determined the crystallization rates and phases formed upon cooling in alloys located in the upper structure of the path after the reflow process: Al31.17Ti18.55Zr1.56V27.53Nb21.19, Al29.61Ti17.62Zr1.48V26.15Nb20.13Fe5.00, Al28.05Ti16.70Zr1.40V24.78Nb19.07Fe10.00, Al26.49Ti15.77Zr1.33V23.40Nb18.01Fe15.00, Al24.94Ti14.84Zr1.25V22.02Nb16.95Fe20.00, Al23.38Ti13.91Zr1.17V20.65Nb15.89Fe25.00, Al21.82Ti12.99Zr1.09V19.27Nb14.83Fe30.00, Al20.26Ti12.06Zr1.01V17.89Nb13.77Fe35.00, Al24.94Ti14.84Zr1.25V22.02Nb16.95Fe40.00, Al15.59Ti9.28Zr0.78V13.77Nb10.60Fe50.00, Al15.59Ti9.28Zr0.78V13.77Nb10.60Fe60.00. The crystallization process from 1600 to 500 °С of the obtained compositions is described using computational methods. When studying the solidification process, it was determined for all compositions that the iron content in the coating is about 10–25 at.% favorable for the formation of a good-quality coating, since at these concentrations the material is in a single-phase region. Keywords: laser cladding, CALPHAD, TermoCalc, laser surface melting, AlTiZrVNbFe DOI: 10.31857/S0235010625020067 |
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Electrical conductivity of salt melts, containing zirconium tetrachloride Salyulev A.B., Potapov A.M. DOI: 10.31857/S0235010625020076
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2025;(2):161-175 | |
| IV All-Russian Conference «Electrochemistry in Distributed and Nuclear Energy
We invite you to take part in the Fourth All-Russian Conference “Electrochemistry in Distributed and Nuclear Energy”, which will be held in the Kabardino-Balkaria Republic (with the implementation of the online format), in the village of Elbrus from June 22 to 27, 2025. The conference is dedicated to the 100th anniversary of the birth of Doctor of Chemical Sciences, Professor, Academician of the Russian Academy of Sciences Alexey Nikolaevich Baraboshkin. |
2025;(2):176-178 |