Research of electrolysis boring products surface of instrumental steels with reverse current in borne-containing oxychloride melt based on CaCl2

E. S. Filatov, N. I. Shurov, K. R. Karimov, E. V. Nikitinа, D. O. Chukhvantsev, N. S. Semenova.

ABSTRACT

Boroning is one of the most effective and promising methods of surface hardening of steel parts of machines and tools operating at high static and dynamic loads. In order to save energy resources and eliminate expensive boron powders, to create a closed cycle for the use of raw materials and wash water, the Institute of High Temperature Electrochemistry Ural Branch of the Russian Academy of Sciences conducted research on the development of technologies for hardening machine parts and tools using electrolysis boronization (electrolysis, electrolysis, cyclic, electrolysis using reverse current) molten salts based on calcium chloride.

The kinetics of the formation of boride coatings on powder steel (GGR) Cr11Ni6Cu15, 20Cr13 in a CaCl₂ + 3–5 wt % B₂O₃ at temperatures of 800, 850 and 900°C and holding times of 1, 2 and 3 hours. The main temperature, concentration and current parameters of the boronation process are determined, which determine the receipt of a high-quality protective coating.

The products of the process of boroning the surface of tool steels in a melt based on calcium chloride with the addition of boron oxide using a reversed current are studied by X-ray phase and micro X-ray spectral analysis. The metallographic method was used to determine the phase composition of the coating from the products of electrolysis boronation. The thickness, microhardness, and phase composition of all obtained boride coatings were determined. The results of boronation of the provided experimental parts allow us to recommend the coating technology for industrial applications.

KEY WORDS:

molten salt, calcium chloride, boron oxide, reverse current, current density, coating, phase composition.

DOI: 10.31857/S0235010621040034

The coefficient of activity of cesium in melts Cs–CsI

V. V. Chebykin, V. M. Ivenko, L. A. Tsiovkina

ABSTRACT

From tensimetric data (20 compositions from 0.39 to 90.0 mol % Cs) of Cs–CsI melts, approximating equations were obtained for the coefficients of cesium activity in specific experiments. The conditions of the experiment and their influence on the error of the experimental data are discussed.

KEYWORDS

melts, solutions, activity coefficients, cesium, cesium fluoride

DOI: 10.1134/S0235010619040054

Density and moline volume of binary mixture melts GdCl3–NaCl and GdCl3–KCl

K. I. Trifonov, I. F. Zabotin, V. E. Krotov, A. F. Nikiforov

ABSTRACT

The density of salt melts of the GdCl3–NaCl and GdCl3–KCl systems was determined by the dilatometric method over the entire concentration range and a wide temperature range. The molar volumes of the systems and their deviations from additivity are calculated. It is established that all the dependences on the composition of the electrolyte are nonlinear. The results can be used in the production technology of gadolinium and its compounds and to clarify the structure of the investigated molten salt mixtures.

KEYWORDS

binary systems, gadolinium trichloride, sodium and potassium chlorides, density, molar volume, isotherms

DOI: 10.1134/S023501061904011X

Liquidus temperatures of KF–KCl–KI melts

A. O. Khudorozhkova, A. V. Isakov, A. A. Red’kin, Yu. P. Zaikov

ABSTRACT

The liquidus temperatures of KF–KCl–KI molten ternary system were investigated using thermal analysis of cooling curves method and STA method. The temperature dependences of liquidus temperature vs potassium iodide concentration for [45KF–55KCl mol %]–KI and [66KF–34KCl mol %]–KI melts were determined. Experimental data are summarized as two dependences of liquidus temperature vs. content of KI in KF–KCl. The thermal analysis data were verified by STA. It was confirmed, the KF–KCl–KI system has a eutectic 25KF–31KCl–44KI (mol %) but with a melting point about 750 K.

KEYWORDS

potassium fluoride, potassium chloride, potassium iodide, liquidus temperature, phase diagram

DOI: 10.1134/S023501061904008X

Dynamics of cluster structure change in melts that forms a continuous series of solid solutions during equilibrium and nonequilibrium crystallization

V. D. Aleksandrov, S. A. Frolova, A. P. Zozulya

ABSTRACT

The scheme of a cluster structure of melts that forms a continuous series of solid solutions in the overheated and overcooled states concerning liquidus temperatures is developed. Structure change dynamics of clusterized liquid during cooling and further equilibrium and nonequilibrium crystallization is analyzed. Coexistence areas of liquid solution with clusters, nucleus and a solid phase are designated. Borders of a clustering and a way of their transformation to nucleus and crystals of solid solutions are defined. The thermograms of cooling characterizing different types of crystallization of alloys are considered. On their basis the analysis of ways of crystallization according to state diagram is given.

KEYWORDS

melts, binary system, alloys, solid solutions, state diagram, solubility, entropy, clusters, clustering, nucleus, equilibrium and nonequilibrium crystallization, thermograms

DOI: 10.1134/S0235010619030034

On the theory of nonstationary growth of spherical crystals from supercooled melts and supersaturated solution

D. V. Alexandrov, I. V. Alexandrova, A. A. Ivanov, A. P. Malygin, I. O. Starodumov, L. V. Toropova

ABSTRACT

The paper presents a theory of the unsteady growth of spherical crystals in supercooled melts and supersaturated solutions. Using the methods of differential series, expansion of unknown functions in a small parameter, and the application of the integral Laplace–Carson transform, the first two corrections to the fundamental contribution to the law for the crystal growth rate were determined. It is shown that the corrections found substantially change the growth rates of spherical crystals in metastable liquids.

KEYWORDS

phase transitions, crystal growth, metastable liquid

DOI: 10.1134/S0235010619030022

Thermodynamics of rare earth chlorides in LiCl–KCl–CsCl eutectic based melts

E. A. Kharina, R. Yu. Kaychenkova, A. S. Dedyukhin,

A. V. Shchetinskiy, L. F. Yamshchikov, V. A. Volkovich

ABSTRACT

In this paper, the temperature dependences of formal standard potentials of some rare earth metals such as lanthanum, neodymium, praseodymium, gadolinium, holmium and erbium and the thermodynamic characteristics of the formation of their chlorides in molten eutectic mixture of lithium, potassium and cesium chlorides were calculated using the experimental data on determination of their equilibrium potentials.

KEYWORDS:

rare earth metals, melts, chlorides, quasi-standard potentiafls, emf method

DOI: 10.1134/S0235010619010079

Thermodynamic parameters anomalies of the heterogeneous system Li2CO3–Na2CO3–K2CO3–nanopowder MgO

I. D. Zakiryanova, I. V. Korzun

ABSTRACT

The method of the differential scanning calorimetry (DSC) has received data on thermodynamic parameters of the heterogeneous system Li2CO3–Na2CO3–K2CO3–nanopowder MgO. Abnormal reduction of temperature and the relative enthalpy of melting of a salt phase at increase in contents in a magnesium oxide composite is established.

KEYWORDS

heterogeneous systems, nanopowder MgO, carbonates of alkaline metals, composite

DOI: 10.7868/S0235010619010249

On the separation of uranium and zirconium: electrochemical properties of zirconium in 3LiCl–2KCl melt

D. S. Maltsev, V. A. Volkovich, E. V. Raguzina, K. E. Strepetov, A. A. Kozlova, M. N. Soldatova

ABSTRACT

Electrochemical properties of zirconium in lithium and potassium chlorides eutectic melt was studied employing solid (tungsten) and liquid (gallium, indium, zinc) cathodes in temperature range 550–750°С.

KEYWORDS

uranium, zirconium, separation, cyclic voltammetry, chloride melts, deposition potentials

DOI: 10.7868/S0235010619010109

Electrochemical properties of tungsten in melts of alkali chloride metals

A. A. Ryzhov, A. B. Ivanov, V. A. Volkovich

ABSTRACT

Anodic dissolution of tungsten in the melts of 3LiCl–2KCl (723–1023 K) and NaCl– 2CsCl (823–1023 K) eutectic mixtures was studied employing high temperature electrochemistry and spectroscopy methods. It was shown that W(IV) ions are transferred to the melt. Formal standard electrode potentials of tungsten were determined.

KEYWORDS

tungsten, chloride melt, electrode potential

DOI: 10.7868/S0235010619010171