Extractive Metallurgy of Nonferrous Metals
Vol’khin A.I. Refining of copper with increased nickel content with the help of silicon-containing reagents
In refining copper from nickel it is expedient to convert it to electrochemically inert silicides, which are concentrated in electrolyte slime, at the stage of fire refining of blister copper. Cu-melt processing by Si-containing reagents is accompanied by reducing its surface tension and deoxidation as well as selective siliconizing of Ni in Cu-melt and formation of the products having fluxing properties. The silicon-containing reagents favorably affect the results of fire and electrolytic refining of copper and its dispersion under the industrial conditions.
Galkova L.I., Naboichenko S.S., Skopov S.V.Kinetics of sulfuric leaching of manganese dioxide
The kinetic regularities of sulfuric acid reducing leaching of uniform manganese dioxide have been studied. The effect of the process variables (temperature, mixing rate, duration, initial acid concentration, consumption of reducer) on the process rate was determined. A generalized kinetic equation of manganese dioxide leaching was proposed. The process was shown to proceed within the pore-diffusion range and be obeyed the regularities of the diffusion mechanism with participation of two reagents.
Extractive Metallurgy of Less-Common and Precious Metals
Naumov A.V.A review of the world market of gallium (Economy of gallium)
Based on the publications of the last years, a review of the present state of the world and Russian markets of gallium and compounds on its base after the 1999- 2001 crisis is given.
Volodin V.N., Khrapunov V.E., Kenzhaliev B.K., Isakova R.A., Moldabaev M. Thermodynamic investigation of the silver-cadmium system with determination of the upper boundary of existence of liquid alloys
Cadmium vapor pressure over binary alloys with silver in a concentration range of 16,97–85,27 at.% at T = 823¸ 1148 K was determined by the boiling point method. Partial and integral thermodynamic characteristics of vapor and condensation phases represented in the form of temperature-concentration dependences were estimated. The system is characterized by the negative deviation from the law of ideal solutions. The boundaries of the liquid-vapor phase transition are determined by extrapolation of pressure dependencies of vapor components onto the area of high temperatures, and the phase diagram of the silver-cadmium system is supplemented. The alloy and vapor interaction area was found to be restricted from above by a relatively small area of existence of liquid Ag- Cd alloys.
Kozin V.F., Bliznyuk A.V. A study of electrochemical behavior of indium in the In0- In2(SO4)3 system by thin-layer electrolytic method
The mechanism and kinetics of indium ionization-discharge process in a cell at small (0,1- 0,2 mm) interelectrode spacing in sulfuric electrolytes have been investigated using cyclic voltammetry. Based on the results obtained, it was suggested that the reduction of In3+ ions proceeds by one-electron mechanism. It has been found that when the potential sweep rate increases up to 5- 10 mV/s the voltammograms exhibit three indium ion reduction peaks. It was shown that a cell of small interelectrode spacing can be used for identifying compounds in intermediate oxidation states.
Ostanina O.I., Bodnar N.M., Buslaeva T.M., Kravchenko V.V., Fyodorova G.A. Chemical condition of osmium in sulfite-sulfate solutions modeling the processing media
It was established that the process of OsO4 reduction by sulfur dioxide in sulfuric solutions is accompanied by formation of some forms of osmium the compositions of which are dependent of component interaction time, concentration of sulfuric acid and existence of Cl– ion in the media studied. The compositions of osmium complexes obtained were determined by elemental chemical analysis, electron, X-ray electron and IR spectroscopy, and thermography.
Troshkina I.D., Ushanova O.N., Shve Khla Piyu, Mukhin V.M., Zubova I.D., Girda T.V. Rhenium sorption from sulfuric solutions by active carbons
Equilibrium and kinetic rhenium characteristics of new active carbon obtained from waste of wood- and corn-working industry compared with PHAS coal have been investigated. The rhenium sorption isotherms from sulfuric solutions (pH = 2) by active carbon SN-G, SU and PHAS are described by Henry’s equation and those by carbon SN-P do by the Langmuir equation. The effective coefficients of rhenium diffusion in active coals were calculated.
Casting Production
Korchmit A.V., Еgorov Yu.P. Defects of castings during centrifugal casting of tin bronzes
Versions of the gas defects arising in centrifugal casts from tin bronzes have been investigated, and the reasons of their occurrence are discussed. A probable mechanism of gas hole formation in a ring made of bronze 7-12-2-3 cast-in in a mold with horizontal rotation axis is considered. Possible measures to prevent gas defect formation are described.
Metal Forming
Sidelnikov S.B. Classification and fields of application of integrated and combined methods to process nonferrous metals and alloys
An analysis of the metal working schemes from the point of view of matching or combining different operations (casting, plastic working, compacting and heat treatment are main of them) is carried out. The classification, which allows us to present the known metal working processes with the help of basic processes and form new combined, matched and matched-combined processes of metal working, has been proposed. The examples of such processes are given and their advantages as compared with the initial ones are described.
Bogatov A.A., Orlov G.A., Pupyshev A.A. Investigation of periodic tube drawing by finite element method
A study of the stress-strain state of metal by the finite element method has been carried out to determine the limiting modes of periodical drawing without exhausting the plasticity resource. It was found that during a mandrel moving cycle, a particle passes three stages of alternating strain the stressed state of which is different. An algorithm and a program for PC calculation of damage of metal being deformed along the motion path of a particle were developed. The damages accumulated in the processes of periodical drawing, cold roller rolling and long mandrel drawing of tubes are compared. It is shown that damage during periodical drawing is much less due to more pronounced alternating deformation. The results of the studies allows us to recommend the above method for production of cold-deformed tubes of ductile alloys (of L96 type) with a reduction ratio less than 8 and those of less ductile alloys with a reduction ration of about 4¸ 6.
Powder Materials and Coatings
Romanov G.N., Flegontov N.R., Savitsky A.P. Volume changes of powder Ti- Ni bodies during sintering
The effect of Ti–Ni powder blending ratios within a range of 0–100 % on shrinkage of compacts during solid-state and liquid-phase sintering has been studied. According to the earlier hypothesis there exist only the S- and V-shaped curves, which describe a component concentration dependence of compaction (residual porosity) of powder compacts as a result of solid state sintering of mixtures. The article shows the concentration dependence of porosity of sintered compacts of the Ti–Ni systems can be referred to the S-sort. Such dependence can be explained on the basis of diffusion interaction of metals applying multiparticle model of a two-component powder compact.
Structural Macrokinetics. Self-Propagating High-Temperature Synthesis
Zamulaeva E.I., Levashov E.A., Kudryashov A.E., Vakaev P.V., Sviridova T.A. Production of heat-resistant metal-ceramic coatings on the basis of titanium silicide and nitride by thermoreactive electrospark surface strengthening
Coatings on the basis of Ti5Si3 titanium silicide have been produced using the Thermoreactive Electrospark Surface Strengthening (TRESS) method. Their formation took place by applying a charge exothermic layer of specified composition (Ti–Si, Ti–Si3N4) onto a substrate and the subsequent chemical conversion in it that is maintained by energy of pulsed discharges. A series of investigations of structure, composition and properties (microhardness, thickness, integrity, and wear-resistance) of TRESS-coatings on OT4-1 titanium alloy was carried out. A dependence of depth of chemical conversion in charge layers on energy processing mode was found. It was established that the coatings produced during optimal processing mode (E = 0,3 J) facilitate increase in microhardness, wear-resistance and heat-resistance of OT4-1 alloy.
Surface Engineering. Multifunctional Films. Corrosion and Metal Protection
Gulevsky S.A., Kostel’tseva N.B., Petelin A.L., Podgorny D.A., Rodin A.O., Smirnov A.N. Formation of cracks and nano-sized films along the grain boundaries during wetting in the Cu- Bi system
The study of nanosized films along grain boundaries in the Cu–Bi system by optical and Auger-electron spectroscopy showed that a film arises as a result of Bi spreading along the cracks that are formed during interaction of liquid bismuth with the grain boundaries in copper in absence of external stresses. An assessment of a portion of surface of boundaries, which are fractured in a brittle manner, is given. Bismuth is shown to be on such boundaries only.
Process Control and Automation
Rutkovsky A.L., Davidson A.M., Chursalova S.S., Starikova T.V. Calculation of the component dissociation degree of during gas fuel combustion
Adequate models were obtained by the method of group consideration of arguments with using two series of selection. The models are intended for calculation of a degree of dissociation of gas fuel combustion products (H2O and CO2) in a temperature range of 1500- 3000 ° C in changing partial pressure of the components from 0,01 to 1 atа. It was established that the processes of CO2 and H2O dissociation can be described by the models identical in mathematical structure, which differ only by numerical values of coefficients. The models obtained are adequate to the experimental data with the confidence probability of 0,99. They allow us to improve accuracy and automatize the calculations of gas fuel combustion.
