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

Research of properties of oxide melts in model experiment

I. A. Babina, A. O. Babin

ABSTRACT

It is shown that the relative number of bridging oxygen atoms in the linkages Si–O–Si with linear decreases in the cases of all modifiers, the rapidity of the decline of the modifiers are arranged in order of MgO, Na2O, Li2O, CaO.

KEYWORDS:

melt, modifier, complexes

DOI: 10.1134/S0235010619010043

Computer simulation of multicomponent melts of metallurgical slags

E. V. Dyul’dina, B. R. Gelchinski, V. N. Selivanov

ABSTRACT

Based on the experimental data on the density, the molecular dynamics simulation of multicomponent oxide-fluoride metallurgical slag-forming systems: SiO2–CaO–Al2O3–MgO–CaF2–Na2O–K2O–FeO was carried out for the first time in the approximation of the ionic bond model. The results were discussed and compared with literary experimental and calculated data. The obtained model indicates a weak temperature dependence of the structure of the melt. An increased diffusion mobility of fluorine ions as well as ions of alkali metals in comparison with other elements has been revealed.

KEYWORDS

melt, metallurgical slag, computer simulation, structure, properties

DOI: 10.1134/S0235010618050055

Model investigation of liquid interaction metal and dispersed steel inclusions in castingon gasificable models

B. S. Vorontsov, N. V. Nesterov

ABSTRACT

A mathematical model for the interaction of liquid metal with metallic inclusions embedded in the foam polystyrene, reflecting the filling of molds, the effect of thermal decomposition of expanded polystyrene and heat exchange of the base alloy and filler material, is developed. The resulted results of the experiment on obtaining prototypes by casting on gasified models, confirming the predictions of mathematical modeling.

KEYWORDS

mathematical model, interaction of metal particles with melt, local alloying, casting for gasified models, composite materials

DOI: 10.1134/S0235010618050158

Corrosion of various types of stainless steels in chloraluminate melts

V. V. Karpov, A. V. Abramov, K. V. Dedov, A. V. Shak, A. Yu. Zhlyakov,

I. B. Polovov, S. V. Belikov, O. I. Rebrin

ABSTRACT

In the present work the corrosion behavior of 08Kh17T (analogue of AISI 439) ferritic steel, 12Kh13 (analogue of AISI 410) and 16Kh12MVSFBR ferritic-martensitic steels, and AISI 316L (analogue of 03Kh16N15M3), 12Kh18N10T (analogue of AISI 321) and 06KhN28MDT austenitic alloys was studied at 550°C in fused KCl–AlCl3 mixture with the initial AlCl3EtoEKCl ratio of 1.1. The corrosion rates of the studied materials in the KCl–AlCl3 were determined. The corrosion processes in all the studied iron-based steels were caused by the red-ox reactions resulting in dissolution of the most electronegative alloy components (Cr, Fe and Mn), that indicate the electrochemical nature of corrosion phenomena.

KEYWORDS

corrosion, stainless steel, chloraluminate melts, intergranular corrosion, molten salt reactor

DOI: 10.7868/S0235010619010067

Formation of phosphates of rare earth elements in melts based on the equimolar mixture of sodium and potassium chlorides

A. B. Ivanov, V. V. Sukhikh, V. A. Volkovich, B. D. Vasin, A. V. Chukin

ABSTRACT

Processes taking part during reaction of chlorides of 15 rare earth elements (yttrium, lanthanum and all lanthanides except for promethium) with sodium orthophosphate in the melts based on NaCl–KCl equimolar mixture under inert atmosphere at 750°C. Phase composition and particle size distribution of the phosphates of rare earth elements (REE) formed was determined. The effect of the mole ratio of phosphate to REE on the composition and particle size of the phosphates formed was studied. Conditions required for the quantitative precipitating from the melt individual REE and a mixture of REE imitating the content of rare earth fission products in the spent nuclear fuels arriving for the reprocessing.

KEYWORDS

rare earth elements, chloride melts, phosphates, precipitation, spent nuclear fuels

DOI: 10.7868/S0235010619010055

Activity of lanthanum in zinc-containing alloys: study of La–Zn, La–U–Zn and La–U–Ga–Zn systems

V. A. Volkovich, D. S. Maltsev, E. V. Raguzina, A. S. Dedyukhin, A. V. Shchetinskiy, L. F. Yamshchikov

ABSTRACT

The effect of alloy components on thermodynamic properties of f-elements was studied on the example of zinc-containing alloys. Activity of lanthanum in La–Zn, La–U–Zn and La–U–Ga–Zn systems, and activity of uranium in U–Zn system were determined at 573–1073 K. The effect of second low melting metal (gallium) and second f-element (uranium) on activity of lanthanum in zinc-containing systems was analyzed.

KEYWORDS

lanthanum, uranium, zinc, gallium, alloy, activity, thermodynamics

DOI: 10.7868/S0235010619010225

Influence of the temperature factor on the morphology of copper-zink alloys at the anode polarization in chloride melt

E. A. Karfidov, E. V. Nikitina, N. A. Kazakovtsevа, V. B. Malkov, N. G. Molchanovа.

ABSTRACT:

The effect of temperature in the range from 350 to 650°С on the morphology of brass grade L63 (37 wt % Zn) was studied during selective anodic dissolution in the eutectic salt melt of lithium, cesium and potassium chlorides. Anodic polarization is accompanied by a change in the state of the surface of the electrodes in connection with the release into the corrosive medium of the electronegative component of the alloy–zinc, as well as the vacancy-induced rearrangement of the electropositive component, copper. The methods of investigation used in this work: microscopy, gravimetry, chemical analysis, and hydrostatic weighing-allowed us to evaluate the patterns of formation of a developed anodic surface under the galvanostatic regime of electrochemical dissolution of a bimetallic alloy. The increase in temperature led to a decrease in the selectivity of dissolution of the alloy, porosity and development of the surface of the resulting materials.

KEYWORDS:

copper alloys, brass, selective dissolution, temperature, porosity, selectivity, developed anodic surface, chloride melt

DOI: 10.1134/S0235010618060026

Phase diagram of the LiCl– MnCl2 binary system

I. V. Korzun, V. N. Dokutovich, E. V. Stepanova, N. K. Tkachev.

ABSTRACT:

Phase diagram of the LiCl–MnCl2 binary system was studied by the method of synchronous thermal analysis. It is established that this system is characterized by the presence of a congruently melting compound Li2MnCl4 (Tm = 855 K) and two eutectics with coordinates Te1 = 829 K; x(MnCl2) = 0.525 and Te2 = 851 K; x(MnCl2) = 0.255. It was found that in the solid state the Li2MnCl4 compound undergoes a secondEorder phase transition at T = 733 K with a jump in the heat capacity Δcp = 117 J/(mol К).

KEYWORDS:

lithium chloride-manganese dichloride, phase diagram, DSC, lithium tetra-chloromanganite

DOI: 10.7868/S0235010618050067

Activity of oxygen in nickel melts containing aluminum, lanthanum and cerium at PAr = 0.1 MPa

V. T. Burtsev.

ABSTRACT:

The deoxidation of nickelEbase superalloys upon vacuum melting was carried out in the presence of Al with strong deoxidizers such as La and Ce. The oxygen activity (a[O]) in the Ni–O–Al (0.001–5%), Ni–O–La/Ce (0.001–0.1%) and Ni–O–Al (5%)–La/Ce (0.001–0.1%) melts at 1560°C and PAr = 0.1 MPa has been studied by the method of instantaneous EMF recording by certified sensors. For the former two melting systems, the a[O] = f[Al/La/Ce%] dependences are described by logarithmic functions. The deoxidizing ability of Ce in the second system is higher by a factor of 4.7 than that of La. For the melts of the third system, the a[O] = f[Al (5%)–La/Ce] dependences constructed in the “spline” regime showed that the introduction of La (0.02–0.05%) decreases a[O] by a factor of 6–8 relative to the data on the second system of melts, and the introduction of Ce (0.02–0.05%) decreases a[O] by a factor of 3–3.4 relative to the data on the second system of melts, and the deoxidizing capacity of Ce remains higher than that of La in the presence of aluminum. Therefore, Ce is preferable as the final oxidizer in the practice of deoxidation.

KEYWORDS:

Nickel-oxygen-aluminum melts, lanthanum, cerium, EMF method, deoxidation

DOI: 10.7868/S0235010618050043