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

Refining of technical silicon melts in the electrical field in helium

A. V. Kaibichev, I. A. Kaibichev

ABSTRACT

Considered common methods for cleaning silicon melts. Substantiated removal of impurities in the electric field. The influence of the composition, temperature, helium purity, transmitted electricity and electric field strength is estimated. The removal of polyatomic and multimolecular ions in an electric field has been established. The relative contribution of the interelectrode transfer and evaporation to the purification of silicon is determined.

KEYWORDS

evaporation, interelectrode transfer, melt, polarity, atomic mass, ions, purification

DOI: 10.1134/S0235010619040066

Electrochemical behavior of the nickel/oxide tungsten bronze system during cyclic potential sweep

A. V. Kosov, O. L. Semerikova, S. V. Vakarin, Yu. P. Zaykov

ABSTRACT

The electrochemical behavior of nickel in the K2WO4–Na2WO4 (1 : 1) – WO3 (35 mol. %) and K2WO4–Na2WO4 (1 : 1) – WO3 (50 mol. %) polytungstate melts was studied by the cyclic voltammetry. Based on a comparison of the obtained cyclic voltammograms with the data of SEM, EDS and XRD conclusions were drawn about the sequence of processes proceeding on the nickel substrate. Equations of the electrolysis products formation are proposed.

KEYWORDS

electrocrystallization, cyclic voltammetry, melt, oxide tungsten bronze, nickel

DOI: 10.1134/S0235010619040091

Connection of acoustic emission with local structural change on melt in non-equilibrium aluminum

V. B. Vorontsov, V. K. Pershin

ABSTRACT

Obtained and analyzed experimental results of investigation of the dependence of energy and number of AE signals from molten metal temperature in the range 680–860°C. The connection of acoustic emission with structural changes in liquid metals on the example of Al melt is established. The models of clusters are given.

KEYWORDS

crystal structure, cluster model, temperature gradient, melt, metals, acoustics

DOI: 10.1134/S0235010619040145

Microstructure of high-strength aluminum alloy after combined surface strength

S. G. Kuptsov, A. V. Elantsev, E. A. Nikonenko, E. V. Nikitina, A. V. Shak, N. A. Kazakovtseva

ABSTRACT

Metallographic studies of carbidoboride coatings on samples of aluminum alloy V96Ts, applied from both sides by the method of electric spark alloying (ESA), were performed. On one side, the coating was further processed with a laser. It is established that the surface with ESA has significant irregularities, pores, cracks, and laser treatment leads to a decrease in roughness. Laboratory tests allowed recommending a combined (electric-spark-laser) method of hardening the surface of specimens of aluminum alloy V96Ts to increase the service life of tools and machine parts.

KEYWORDS

coatings, doping, laser processing, carbidoborides, aluminum

DOI: 10.1134/S0235010619040108

Features of technical silicon cleaning in melting in helium with impact on electric field melt on molybdenum and graphite electrode

A. V. Kaibichev, I. A. Kaibichev

ABSTRACT

The features of the purification of technical silicon in helium with molybdenum and graphite cathodes are considered. The formation of silicides and carbides in the melt is substantiated. The effect of melt polarity on the removal of impurities and gases is shown. The evaporation of technical silicon and the interelectrode transfer of elements are quantitatively determined. The efficiency of evaporation and removal of impurities in an electric field is estimated.

KEYWORDS

iron, titanium, silicon, silicides, carbides, melt, electricity

DOI: 10.1134/S023501061903006X

Relaxation time to the steady-state growth of secondary dendritic branches

E. A. Titova, D. V. Alexandrov, P. K. Galenko

ABSTRACT

In this paper, the expression for the time of reaching the stationary mode of growth of secondary branches of dendritic crystals is theoretically determined. The dependences of the time of transition to the stationary mode on the Peclet growth number and the tip growth rate for nickel and succinonitrile dendrites are plotted. It was shown that during high-speed crystallization, the secondary branches of dendrites enter the steady-state growth mode faster than in the case of low-speed crystallization. The growth of the secondary branches of dendrites can almost always be considered stationary in cases of low-speed, moderate and high-speed crystallization.

KEYWORDS:

phase transformations, dendrites, supercooled melt

DOI: 10.1134/S0235010619020051

Bond energies in the molten M–Al–Zr–O–F systems (M = Li, Na, K)

A. S. Vorobiov, A. V. Suzdaltsev, A. E. Galashev

ABSTRACT

The bond energies in complex anions formed from the components Al–F, Zr–F, Al–OF, and Zr–OF were calculated in Siesta program using first-principle molecular dynamics. These anions are formed at the dissolution of ZrO2 and Al2O3 oxides in fluoride MFEAlF3 melts (where M = Li, Na, K). An influence of anions composition as well as the cation nature in the second coordination sphere on the bond energies in the anions was determined. It was shown that the Al O F2 and Zr O F2 anions are most stable among analyzed oxygen-containing anions. At the same time anions formed by zirconium have the lowest bond energies. Replacement of the cation in the second coordination sphere of the M2Al2O2F6 and M2Zr2O2F6 anions in the range from K to Li leads to a decrease in the bond energy.

KEYWORDS:

oxide-fluoride melt, anions, zirconium, aluminum, molecular dynamics simulation, bond energy, stability

DOI: 10.1134/S0235010619020063