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

Viscosity of liquid alumentric composite Al–7% Si + 5% Al2O3

A. B. Finkelstein, O. A. Chikova, M. Makhmudzoda, V. V. Viukhin

ABSTRACT

The kinematic viscosity of a liquid aluminum matrix composite (Al–7% Si + Al2O3) obtained by the method of purging a pre-hydrogenated melt with oxygen was studied using the method of torsional vibrations in comparison with the initial alloy. The photometric method revealed the proportion of oxide particles in the aluminum matrix. The absence of branching of polytherm melt composite material, which is associated with its inherent microheterogeneity. The possibility of predicting the viscosity of a composite material from known dependencies is shown, taking into account the fragmentation shape of the particles of the dispersed phase. The obtained data can be used to calculate the gating systems.

KEYWORDS

composite material, particles, dispersion medium, kinematic viscosity, Einstein equation, microheterogeneity

DOI: 10.1134/S0235010619040042

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

Corrosion-electrochemical behavior of nickel in the LiCl–KCl melt, containing lantan trichloride

E. A. Karfidov, E. V. Nikitina

ABSTRACT

The effect of temperature in the range from 500 to 800°C on nickel (N1) corrosion was studied during testing in a salt melt of a eutectic mixture of lithium and potassium chlorides, with the addition of lanthanum trichloride from 0.5 to 2 mol. %. The corrosion rate of nickel increases with increasing temperature, the addition of lanthanum chloride reduces the corrosion rate at 500–650°C (inhibition of the shielding type due to the subsequent chemical reaction). The corrosion potential of nickel is approximately –0.5 V relative to the silver chloride electrode at a temperature of 500°C and decreases slightly with increasing temperature, and does not depend on the concentration of lanthanum chloride. To concretize the mechanism of corrosion damage, the current-voltage curves were taken with the content of lanthanum chloride 0.5 and 2 mol. % at sweep speeds of 10 and 20 mV/s. X-ray phase and micro X-ray spectral analysis methods were used. The sweep speed does not affect the course of the irreversible electrochemical oxidation process, and the addition of lanthanum chloride increases the current density in the anode region tenfold. Comparison of corrosion rates obtained by gravimetric and chemical-analytical methods, allows us to speak about the electrochemical mechanism of corrosion.

KEYWORDS nickel, chloride melt, corrosion, lanthanum trichloride, temperature, surface morphology

DOI: 10.1134/S0235010619040078

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