Category Archives: metallurgy

Influence of niobium and tantalum on peculiarities of phase formation at metallothermic interaction between aluminium and titanium dioxide

T. V. Osinkina, S. A. Krasikov, E. M. Zhilina, S. N. Agafonov,

L. B. Vedmid, S. V. Zhidovinova

ABSTRACT

Thermodynamic modeling of joint aluminothermic reduction of titan, niobium and tantalum from oxides have been carried out. The results were coordinated with research of this process by a method of the combined scanning calorimetry and indicators of metal-thermic obtaining alloy Al–Ti–Nb in the laboratory electric furnace.

KEYWORDS

thermodynamic modeling, aluminothermic reduction, alloy, intermetallic compounds, oxides

Stratification of liquid Pb–Bi alloys of different composition in glass capillaries

N. P. Ouglev, N. S. Boosov

ABSTRACT

The process of stratification of binary melts in the entire concentration range of the lead-bismuth system is studied. The correlation of results of stratification with the type of the state diagram, as well as with other physicochemical properties of melts of the system is shown. The results of the experiment confirm the absence of a stratification mechanism based on the Marangoni–Gibbs effect. The absence of stratification of gallium isotopes in the liquid metal under conditions corresponding to the experiment with lead-bismuth melts is shown experimentally. This clearly confirms not only the absence of a three-dimensional mechanism of stratification associated with the movement of individual atoms, but also indicates the mechanism associated with the formation of structures of atoms of components having different density and different chemical potential in the gravitational field. The comparison with the dynamics of melt stratification of lead-tin indicates the absence of mechanical resistance in this process, which confirms the previously proposed mechanism of transfer of components over the interphase space between the melt and the capillary wall by atoms in the state of two-dimensional super fluidity gas.

KEYWORDS

metal melt, the stratification in the capillary, cluster, barometric distribution, molten Pb–Bi, the correlation of the stratification, the stratification of the isotopes

Experimental estimation of peculiarities of interaction of titanium oxides and gadolinium with aluminum

L. B. Vedmid, E. M. Zhilina, S. A. Krasikov, A. G. Merkushev

ABSTRACT

Theoretical and experimental evaluation of the aluminothermic reduction processes of titanium and gadolinium from oxides allowed us to establish the sequence of compounds formation in the Al–TiO2–Gd2O3 system. It was noted that the reduction is a two-stage process, proceeds through the stage of titanium monoxide formation, followed by formation of intermetallides Al3Ti and GdAl2.

KEYWORDS:

titanium alloy, aluminothermic reduction, phase formation, gadolinium, intermetallic compounds

Modifiing effect of zarconium oxide nanoparticles in electric arc welding

A. B. Finkelstein, V. V. Kartashev, M. V. Fominykh, E. I. Denisova, A. V. Berezovsky

ABSTRACT

The structure of weld metal, made by flux-cored wire with the addition of 0.3% of zirconium oxide at the beginning of scaly morphology, was investigated. The structure of the seam represents needle ferrite. This can be said that the dissociation of zirconium oxide in an electric arc is not an obstacle to the modifying effect that manifests itself both in the course of the interaction of zirconium with oxygen and in the surface activity of zirconium in a crystallizing melt based on iron. Zirconium oxide, thus, is a modifier of both the first and second kind for the crystallizing weld metal. Excess oxygen, presumably, forms seam pores with a diameter of less than 1 m, which, however, does not significantly affect the mechanical properties of the welded seam. The bottom line: the obtained data will be used in the development of electrode materials for the welding of tubular steels.

KEYWORDS:

electric arc welding, nanoparticles, zirconium oxide, modification, needle ferrite

On the motion nature of the atoms in metallic melt

N. P. Uglev, S. N. Uglev

ABSTRACT

The paper analyzes the experiments on metal melt stratification in inclined zigzag capillaries with a mechanical potential barrier preventing the through movement of clusters or microcrystals of metals, in comparison with similar processes in the direct inclined capillary. It is shown that in the transition to a complex capillary with a potential barrier of greater height, the penetration of individual atoms through the barrier almost completely stops. The comparative analysis of the velocities of the processes of capillary stratification and diffusion, as well as the influence of temperature on them, performed within the framework of the previously proposed model of liquid metal in the form of an ultra-colloidal system of solid particles separated by a monoatomic layer of super-fluid atoms, in conjunction with the results of other experiments, allows us to conclude that there are no continuous mechanical oscillations of atoms in the field of interaction potentials. The particle system, in both solid and liquid States, is a degenerate Bose condensate. The mechanisms of energy storage and melting in such a system, as well as diffusion and capillary stratification processes in metal melts are proposed.

KEYWORDS: stratification, inclined capillary, zig-zag capillary, coiled capillary, a metal melt, barometric distribution, diffusion, super fluidity in the melts

Analysis of kinetics of germany and mass crystallization of reduced melt in accordance with thermo-graphics of fleecibility

V. D. Aleksandrov, A. P. Zozulya, A. Yu. Sobolev

ABSTRACT

Based on the information obtained during the decoding of the thermograms of heating and cooling of simple substances, the cluster-coagulation model of supercooled melts crystallization has been further developed. Three successive stages of solidification are described in detail: nucleation, coagulation of nucleus and isothermal crystallization. Equations are proposed for calculating the various kinetic and thermodynamic parameters of crystallization (temperature and melting enthalpy and crystallization, incubation period of a new phase nucleation, degree of pre-crystallization supercooling, time and velocity of explosive crystallization, time and velocities of phase transformations etc.). Using the characteristics of the crystallization process found using thermograms, the critical dimensions of the crystal nuclei and the work of their formation, the degree of crystallinity, the nucleation constants and the Avrami parameters, the energy of coagulation of the nucleus, the isothermal precrystallization constants etc.

KEYWORDS:

crystallization, melting, nucleation, thermal analysis, thermogram, supercooling, tin.

Thermodynamic analysis of oxidation of radioactive graphite in the melt Na2CO3–K2CO3–Sb2O3 in the carbon dioxide atmosphere

N. М. Barbin, I. A. Sidash, D. I. Terentyev, S. G. Alekseev

ABSTRACT

Currently in the world there are power reactors, reactors for plutonium production and research reactors whose number is more than 100 pieces of Graphite in the above mentioned reactors is used as the reflector, moderator, and also as Fuel cladding. Flameless combustion is a promising method of reducing the amount of solid radioactive waste. Method of flameless combustion is based on the oxidation of TRO in the oxide-carbonate melts and significantly reduces the volume of radioactive graphite. Thermodynamic modeling of oxidation of radioactive graphite in molten Na2CO3–K2CO3–Sb2O3 in an atmosphere of carbon dioxide. To conduct thermodynamic analysis was used the program complex TERRA. Thermodynamic modeling was carried out with initial pressure of one atmosphere, at an initial temperature of 273 K and the final temperature 3273 К. The step change in temperature is 100 K. Based on these data, the analysis of the distribution of elements between the condensed and gas phases. The modelling shows that the carbon disappears at a temperature of 873 K.

The heating of the system up to 1073 K leads to the evaporation of condensed compounds of antimony. The heating system up to 1673 K leads to the evaporation of condensed compounds of potassium, sodium, chlorine, uranium and cesium. The heating system up to 2273 K, leads to evaporation of condensed compounds of nickel. The heating system up to 2573 K leads to the evaporation of condensed calcium compounds, plutonium, beryllium, strontium, americium and europium. At temperatures above 2573 K, there is only a steam and gas phase.

 

KEYWORDS:

thermodynamic modeling, radioactive graphite, radionuclides, heating, oxidation, melt, carbonates.

Processing of Zn–Pb–Ag alloys vacuum distillation

A. A. Korolev, S. A. Krayukhin, G. I. Maltsev,

V. G. Lobanov, E. S. Filatov, V. M. Ivenko.

ABSTRACT:

In the processing of lead is formed of silver foam (SP), which requires complex processing, with commercial production of single products. One of the possible ways of SP recovery is vacuum distillation, which is considered one of the most effective and environmentally friendly methods for the separation and purification, processing and refining of various metals. The aim of this work is to determine quantitative and qualitative composition of the products of vacuum distillation are different in composition of polymetallic alloys Zn–Pb–Ag depending on the temperature, pressure and gas environment and in assessing the possible use of calculated equilibrium phase diagrams “gas–liquid” VLE (vapor liquid equilibrium) for predicting technological parameters of the refining joint ventures. It is established that the zinc in the source content in the alloy is 0.4 to 16.7 wt.% speeds of more than 95% within 3 hours at a temperature of 1473 K and a pressure of 1 · 105 Pa. When sublimation of the zinc in the air and the contact of the condensate with water vapor at elevated temperatures oxidizes ~14% of the metal that recommends carrying out the process in inert gas argon. At a temperature of 1323 K and the duration of the distillation 14 hours reducing the pressure in the system from 133 to 7 Pa increases the content of silver 0.046–of 3.48% in the condensate of lead up 98.61–95.94%. At step heating to 1373 K and P = 13 Pa with an exposure of 0.4 hour at 873 K and 1173 K, and the duration of the sublimation 1 hour lead content of the distillation residue amounted to 3.61%, and silver in the sublimates of lead – 0.046%. Deficiencies identified during use of dust products – mechanical ablation or under vacuum, or in the case of allocating a large volume of vapor of volatile components when heated.

KEY WORDS:

zinc, lead, silver, component, vacuum distillation, temperature, pressure, argon, equilibrium phase diagram.

The thermostability and deformation mechanics in reinforced with graphene and silicene layered and matrix nanocomposites

V. A. Polukhin, N. A. Vatolin.

ABSTRACT:

In the present article there are under the consideration the possibilities of improving the structural and thermodynamic stabilities of metal/2D-crystal interface state, that are determined the fundamental characteristics of the layered and matrix metal/graphene and silicene nanocomposites (Me/2D-G и Me/2D-Si; Me: Al, Mg, Ir, Pd, Ru, Ni, Ti, Ag) produced by pre-operational graphene (silicene) nanoparticle dispersion or in the frame of the additive 3D typing technology (vapor-gas synthesis or CVD) with layered metal atom deposition (or as the crystalline/amorphous nanofilms) on graphene or silicene planes (1 or few lays) as substrates. The systematical analysis of the experimental available data and the original theoretical results received with combined DFT and molecular dynamics methods and concerning with nanocomposites displayed the specific structures, mechanical strength and unique electronic properties.

KEY WORDS:

2D-crystal, graphene, silicone, metallic nanofilm substrates, transition metals interatomic and electronic interaction, electronic charge doping, hybridization, sorption, interface, layered composite, reinforcing, thermostability, tensile strength, strength modulus, scanning tunneling microscopy.