Showing papers in "Russian Journal of Non-ferrous Metals in 2007"
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TL;DR: In this paper, the contemporary state of the world market for rhenium and the economics of production and trends of development of Rhenium-containing products are reviewed on the basis of publications of recent years.
Abstract: On the basis of publications of recent years, the contemporary state of the world market for rhenium and the economics of production and trends of development of rhenium-containing products are reviewed
58 citations
TL;DR: In this paper, the effects of the temperature and duration of the process and of the catalyst-layer height on the sublimation reprocessing of spent catalysts based on molybdenum and cobalt oxides that have been employed for hydrorefining of oil products from sulfur were studied.
Abstract: Effects have been studied of the temperature and duration of the process and of the catalyst-layer height on the sublimation reprocessing of spent catalysts based on molybdenum and cobalt oxides that have been employed for hydrorefining of oil products from sulfur. Some difficulties arising during the reprocessing of such man-caused waste products are discussed and ways for the elimination of these difficulties are suggested.
22 citations
TL;DR: A review of the modern state of the world and Russian markets of bismuth is made and an attempt of prognosing the further development and perspectives in this field is given.
Abstract: Based on the publications of recent years, a review of the modern state of the world and Russian markets of bismuth is made and an attempt of prognosing the further development and perspectives in this field is given.
19 citations
TL;DR: In this article, the authors investigated the thermal oxidation resistance of nanopowders of vanadium, titanium, chromium, and zirconium, as well as silicon carbide, and found that at the temperature of onset of oxidation in air, they are arranged into the following series: carbides TiC (548 K), VC and Cr3(C 0.80N0.20)2 (553 K), ZrC (560 K), and SiC (905-913 K).
Abstract: Thermal oxidation resistance in air of nanopowders of carbides and borides of vanadium, titanium, chromium, and zirconium, as well as silicon carbide, is investigated. It is found that, at the temperature of onset of oxidation in air, they are arranged into the following series: carbides TiC (548 K), VC and Cr3(C0.80N0.20)2 (553 K), ZrC (560 K), and SiC (905–913 K), and borides VB2 (620 K), TiB2 (643 K), CrB2 (763 K), and ZrB2 (823 K). The results of investigation allow one to recommend nanopowders of carbides and borides for use as strengthening phases of composition coatings that operate in oxidizing media at temperatures no higher than the onset of oxidation. Nanopowders of chromium and zirconium borides and silicon carbide can be considered as equivalent substitutes for diamond nanopowders in composition coatings.
16 citations
TL;DR: In this paper, a correlation between the processes of the production (using vacuum-arc evaporation or a special combined method) of nanodimensional coatings on the basis of the Ti-Zr-N system and the processes proceeding in the near-surface layers of the material of the sputtered and evaporated targets was established.
Abstract: The stabilization and interpretation of properties of ion-plasma-produced multicomponent nanostructured coatings (MNCs) is a fairly complicated problem because of a great variety of factors which influence their characteristics. This work is aimed at the establishment of a correlation between the processes of the production (using vacuum-arc evaporation or a special combined method) of nanodimensional coatings on the basis of the Ti-Zr-N system and the processes proceeding in the near-surface layers of the material of the sputtered and evaporated targets. The coatings were obtained using a modernized URMZ.279.048 setup equipped with two electric-arc vaporizers and four dc magnetrons. The structure, properties, and morphological features of MNCs and the relief of the target surfaces were investigated using a Nanoskan atomic-force microscope, a CARL ZEISS LEO 1430 VP scanning electron microscope, and an Umka scanning tunneling microscope. A difference in the processes that take place on the surface of the evaporated and sputtered targets has been established and their analogy with the processes of MNC formation was revealed for the first time.
15 citations
TL;DR: Based on publications of recent years, the modern state of the world market of germanium and germium-containing products after the depression of 1999–2000 years is reviewed.
Abstract: Based on publications of recent years, the modern state of the world market of germanium and germanium-containing products after the depression of 1999–2000 years is reviewed.
14 citations
TL;DR: In this article, the authors studied the regimes of heat treatment of quenched magnesium alloys with a purpose of obtaining a fine-grained structure and showed that the best characteristics of superplasticity are manifested by the ZRE1 and QE22 alloys.
Abstract: A necessary microstructural condition for the manifestation of the effect of superplasticity in alloys is a small grain size (d 100 μm. We have studied the regimes of heat treatment of such materials in AZ91, AE42, QE22, and ZRE1 alloys with a purpose of obtaining a fine-grained structure. The optimum temperature of overaging of quenched magnesium alloys lies between 300 and 350°C. After hot pressing of heat-treated alloys, the average grain size is 6.4 (AZ91), 6.2 (AE42), 1.2 (ZRE1), and 0.7 (QE22) μm. The best characteristics of superplasticity are manifested by the ZRE1 and QE22 alloys with a relative elongation of 750% and strain-rate sensitivity m = 0.75 at T = 420°C and strain rate
$$\dot \varepsilon $$
= 3 × 10−4 s−1. Under these conditions, the AZ91 and AE42 alloys have δ ≤ 260% and m = 0.45.
14 citations
TL;DR: In this paper, the effect of nanodispersed additives of ZrO2, Al2O3, NbC, W, WC, and WC-Co into the composition of the TiC-Ti3AlC2 electrode on the kinetics of formation of coatings by electrospark doping was investigated.
Abstract: The effect of nanodispersed additives of ZrO2, Al2O3, NbC, W, WC, and WC-Co into the composition of the TiC-Ti3AlC2 electrode on the kinetics of formation of coatings by electrospark doping (ESD) on the titanium alloy of the OT4-1 grade on varying the duration of pulsed discharges in a wide range is investigated. The structure, phase composition, properties (continuity, thickness, microhardness, friction coefficient, wear resistance, and heat resistance) are investigated. The optimum energy mode of the ESD treatment of the OT4-1 titanium alloys by new electrode materials is determined. It is found that the introduction of a nanodispersed component is favorable to an increase in continuity and the microhardness of electrospark coatings and a substantial increase in wear resistance and heat resistance of titanium alloys.
12 citations
TL;DR: In this paper, the authors investigated the contact deposition of gold by a magnesium powder in a hydrodynamic mode in 0.001-0.005 M solutions of the system [Au(CN)2]−-CN−.
Abstract: Contact deposition of gold by a magnesium powder in a hydrodynamic mode in 0.001–0.005 M solutions of the system [Au(CN)2]−-CN− is investigated. It is found that the cementation rate of gold (V
c
) is directly proportional tot he concentration of the [Au(CN)2]− complex and the area of the cementing agent. As the temperature is increased in the ranges 20–30 and 30–40°C, the increase in V
c
is 20–25 and 8–10%, respectively. The time dependence of degree of gold extraction on magnesium has an extreme character due to the increasing rate of the inverse process of leaching. In an ultrasonic field, the cementation rate and degree of gold extraction increase. This phenomenon is conditioned by destruction of the hydroxide film on the magnesium surface. The deposited gold has a film nature.
8 citations
TL;DR: In this article, the partial and integral thermodynamic properties of Pb-Sb alloys containing 20-95 mol % Pb were investigated by the method of measurement of equilibrium emf values in the range T = 723-873 K in a molten mixture of potassium and lead chlorides.
Abstract: Thermodynamic properties of Pb-Sb alloys containing 20–95 mol % Pb are investigated by the method of measurement of equilibrium emf values in the range T = 723–873 K in a molten mixture of potassium and lead chlorides. The partial and integral thermodynamic characteristics of the system are calculated, and small negative deviations from ideality are revealed. The extremum of integral functions of mixing lies in the region of 0.55 mole fraction of Pb. The system could not be treated as a regular solution since the excess entropy introduces a considerable contribution to deviation from ideality, while the excess Gibbs energy differs considerably from the heat of mixing.
7 citations
TL;DR: In this paper, the phase diagram of the quasi-binary join Al-Al8CeCu4Al8 was investigated and the region of optimal compositions of alloys based on the eutectic reaction L → (Al) + CeCu 4Al8 were shown to lie in narrow limits.
Abstract: Phase diagram of the Al-Cu-Ce system is investigated in the region of the quasi-binary join Al-Al8CeCu4. The parameter of the eutectic reaction L → (Al) + CeCu4Al8 are found: T = 610°C; composition 14% Cu and 7% Ce. This eutectic has a dispersed structure, and the ternary compounds, which is involved in the eutectic, is capable to fragmentation and spheroidism in the course of heating starting from 540°C. It is shown that the region of optimal compositions of alloys based on the eutectic (Al) + CeCu4Al8 lies in narrow limits. This is caused by the fact that an abrupt decrease of the solidus and, as a consequence, significant broadening of the crystallization range occurs at a relatively small deviation from the ratio Cu: Ce = 2.
TL;DR: In this article, the effect of various oxidizers used in the process of leaching on the extent of extraction of rhenium remained in the calcine as a result of incomplete sublimation upon the oxidation roasting of molybdenite concentrate in a tubular furnace.
Abstract: Consideration is given to the effect of various oxidizers used in the process of leaching on the extent of extraction of rhenium remained in the calcine as a result of incomplete sublimation upon the oxidation roasting of molybdenite concentrate in a tubular furnace. Its maximum extraction αRe = 88%) is reached when using manganese concentrate. It has been established that for the Almalyk Metallurgical Integrated Works the most suitable oxidizer is a mixture of nitric and sulfuric acids (αRe = 71–73%); in this case, a virtually complete purification of the calcine from copper takes place (≤0.05–0.07% Cu is retained in it). It is shown that molybdenum and rhenium that passed into solution can be separated by precipitation and ion-exchange methods.
TL;DR: In this article, the authors investigated the high-temperature synthesis of the Ni3Al intermetallic compound in the thermal explosion mode under the pressure of a powder mixture of nickel and aluminum of a stoichiometric composition.
Abstract: We investigate by experimental and numerical methods the high-temperature synthesis of the Ni3Al intermetallic compound in the thermal explosion mode under the pressure of a powder mixture of nickel and aluminum of a stoichiometric composition. The calculated and experimental thermograms of self-propagating high-temperature synthesis are analyzed depending on the temperature of preliminary heating of the powder mixture and the magnitude of external pressure.
TL;DR: In this article, the present-day state of nanotechnologies in the world based on use of the following criteria; quantity of registered patents, quantity of published works and invested resources is realized.
Abstract: Analytical investigation of present-day state of nanotechnologies in the world based on use of the following criteria; quantity of registered patents, quantity of published works and invested resources is realized. In accordance with given criteria world leaders in the sphere of nanotechnologies are the USA, Japan, countries of European Community and China. Leading spheres of nanoindustry and dominating tendencies of its development are specified. Useful increase of capacities production’s science intensive produce based on use of nanotechnologies is forecasted.
TL;DR: In this article, five different representations of froth flotation are considered: hysteresis, electrostatic, capillary, jointly radiographic and luminescent, and sophistic presentations.
Abstract: From the viewpoint of experimental substantiation and usefulness for the selection of reagents for froth flotation, five different representations are considered that interpret the causes of selective capture of particles by bubbles. These are the hysteresis, electrostatic, capillary, jointly radiographic and luminescent, and sophistic presentations, which were popular in the past, then rejected, and now are being developed again; they, however, contain substantial errors. Quantitative analysis has shown us that capillary presentations are preferential, with the use of which it proved possible to establish the effect that the electrical charge of the particle surface (or the ionic composition of the pulp) had on the absorption of neutral organic molecules on the surface; to determine the nature of forces that keep the particles on the bubbles; to find the interlayer of the liquid between the bubble and the substrate; to determine the properties of thin layers of the liquid, which are the “glue” keeping the particles on the bubble; to reveal the structure of the boundary layers of the liquid that are in contact with the solid and gas phases; to introduce the quantitative criterion of nonequilibrium for the characteristics of the properties of reagents, which manifest themselves in the dynamic conditions of froth flotation and, the most important, which are based on capillary physics, in order to calculate various models of froth flotation to reveal their mechanism and the causes of existence; to find the optimal conditions for solving concrete problems and the modes of conducting reagent-free, ecologically pure froth flotation. It is also important that the capillary representations allow one to easily recognize the incorrectness of not only the previously wide-spread popular (sophistic) hypotheses, but certain modern ones as well.
TL;DR: In this article, the effect of the amount of additives of the tantalum-carbon mixture with respect to the weight of the starting charge is investigated and the regularities of phase formation and structural formation in synthetic products are analyzed.
Abstract: We present the results of investigations of synthesis in a burning mode of tissue-compatible compact composition materials of tantalum-containing target cathodes (Ti, Ta)Cx + Ca3(PO4)2 obtained by forced SHS compaction from a Ti + Ta + C + Ca3(PO4)2 mixture and assigned to the ion-plasma deposition of nanostructured tissue-compatible coatings. The effect of the amount of additives of the tantalum-carbon mixture with respect to the weight of the starting charge is investigated. Regularities of phase formation and structural formation in synthetic products are analyzed. A new and important feature is that there is no dependence of the burning velocity and temperature on the relative fraction of the Ta + C mixture. In the temperature profiles, two characteristic peaks of heat release were detected. These peaks indicate that parallel and sequential chemical reactions of the formation of titanium and tantalum carbides proceed. The growth of the relative fraction of the Ta + C mixture led to modification of the carbide structure, to an increase in the residual porosity, and to a considerable increase in hardness.
TL;DR: In this article, the authors considered metal sulfides as compounds of oppositely charged species formed owing to the totality of electrostatic and coordination binding in the Mez+-S2− system.
Abstract: Existing notions on reduction of metals from oxides and sulfides are based on realization of dissociative processes associated with the formation of simple substances. Metal sulfides can be considered as compounds of oppositely charged species formed owing to totality of electrostatic and coordination binding in the Mez+-S2− system. Reduction of metals from such compounds with the use of donor properties of sulfide sulfur is an electrochemical process with the participation of the electrode pair Mez+ and S2− in the mode of internal electrolysis in the system, which provides utilization of elemental sulfur that is formed through chemical reactions. As an electrochemical medium, molten caustic soda is proposed. In its presence, elemental sulfur disproportionates with the preferential accumulation of sulfide and sulfate sulfur. The reaction causes irreversibility of the reduction process.
TL;DR: In this article, the phase transition of dicalcium silicate has been investigated and it is shown that rapid cooling is accompanied by delay of structural processes, which leads to a decreasing in temperature of the phase phase transition α′====== L.............. → β-Ca2SiO4.
Abstract: Experimental results are presented showing that rapid cooling of dicalcium silicate is accompanied by delay of structural processes, which leads to a decreasing in temperature of the phase transition α′
L
→ β-Ca2SiO4. As starting materials, nepheline ore and limestone were used. In preparing the charge, the dosage of starting components was calculated for obtaining a molar ratio of CaO/SiO2 = 2.0. From the charge, the series of samples was prepared. Each of the samples was sintered to t = 1250°C with subsequent keeping of the material at this temperature for 30 min. Then the samples were subjected to rapid cooling in air to t = 750, 650, 550, 450, 350, 250, 150, and 25°C. By means of quantitative X-ray powder diffraction analysis using a DRON-3 setup, the content of α′
L
and β-Ca2SiO4 was determined in the samples. The data allow us to suppose the occurring polymorphic transformations in dicalcium silicate have a resonance character.
TL;DR: In this paper, the main areas of application of solid alloys with nanodimensional structural elements are noted, and the technologies of their obtainment and production based on their WC-Co solid-alloys are reviewed.
Abstract: Publications on ultradispersed and nanodimensional powders of tungsten and its carbide and the technologies of their obtainment and production based on their WC-Co solid alloys are reviewed. The main areas of application of solid alloys with nanodimensional structural elements are noted.
TL;DR: In this article, the effects of a preliminary mechanochemical activation of a cordierite charge prepared from of natural raw materials on the strength of high-porosity articles obtained by the method of polymeric-matrix duplication have been studied.
Abstract: Effects of a preliminary mechanochemical activation of a cordierite charge prepared from of natural raw materials on the strength of high-porosity articles obtained by the method of polymeric-matrix duplication have been studied. It has been shown by the methods of differential thermal analysis, electron-microprobe analysis, and infrared spectroscopy that in an aqueous medium with additives of Trilon B the beginning of the synthesis of cordierite can be fixed already in the course of mechanical activation and that during dry processing using titanium carbide the first to be formed is rutile, which reacts with the kaolinite. It is shown that the introduction of Trilon B upon the activation of the charge in an aqueous medium ensures a steady increase in strength with a satisfactory quality of the cordierite produced and that the addition of titanium carbide intensifies the process of the cordierite synthesis and ensures a considerable growth of the strength of the highly porous permeable cordierite ceramics.
TL;DR: In this article, a simple quantitative method of estimating the transformation of ferrous phases during homogenizing annealing by varying the shape of particles is suggested, which is used to analyze the degree of the procession of homogenization in the low-doped alloy 6060 (6063) and select the optimal mode of isothermal keeping.
Abstract: A simple quantitative method of estimating the transformation of ferrous phases during homogenizing annealing by varying the shape of particles is suggested. This method was used to analyze the degree of the procession of homogenizing annealing in the low-doped alloy 6060 (6063) and to select the optimal mode of isothermal keeping. By the results of analysis, the expedience of increasing the annealing temperature to 600°C is demonstrated.
TL;DR: In this paper, a method for investigation of liquid-metal etching grooves that form owing to wetting and penetration of the liquid phase along the triple grain-boundary junctions (triple junction) and grain boundaries in the Al-Sn system is described.
Abstract: A new procedure for investigation of liquid-metal etching grooves that form owing to wetting and penetration of the liquid phase along the triple grain-boundary junctions (triple junction) and grain boundaries in the Al-Sn system is described. The investigations were carried out by the method of layer-by-layer polishing of the end surface of the wetted sample. The obtained slices were investigated by methods of optical and electron scanning microscopy. It was shown that the groove depth is virtually invariable along a single grain boundary and increases as the groove approaches the triple junction. The penetration depth of Sn along the triple junctions is much larger than along the grain boundaries. It is shown that, owing to wetting processes in the triple junction, as in the grain boundaries, the Sn-based alloy is formed.
TL;DR: In this article, the authors investigated the kinetic regularities of Sn-Ag liquid alloys at T = 1273 K in air and found that the limiting wetting angle of liquid silver on tin dioxide is invariable and amounts to 72.4° ± 4.3°.
Abstract: Kinetic regularities of oxidation of Sn-Ag liquid alloys at T = 1273 K in air are investigated. The so-called catastrophic oxidation of melts containing 70 and 80 at % Ag is found. X-ray powder diffraction analysis of the scale forming on all Sn-Ag alloys, including such oxidation, showed that it consists of SnO2 and silver metal. It is found that, in the range T = 1234–1303 K, the limiting wetting angle of liquid silver on tin dioxide is invariable and amounts to 72.4° ± 4.3°.
TL;DR: In this paper, the fabrication and properties of the surface layer on copper are investigated after deposition and thermal treatment of the aluminum gas-thermal coating, which leads to the formation of a protective diffusion layer having high physical, mechanical, and performance characteristics.
Abstract: The fabrication and properties of the surface layer on copper are investigated after deposition and thermal treatment of the aluminum gas-thermal coating. This process leads to the formation of a protective diffusion layer having high physical, mechanical, and performance characteristics.
TL;DR: In this article, the physicochemical properties of aluminum hydroxychlorides (AHOCs) of various basicity (1/3, 2/3 and 5/6) have been considered.
Abstract: Physicochemical properties of aluminum hydroxychlorides (AHOCs) of various basicity (1/3, 2/3, 5/6) have been considered. Dependences of their density and viscosity on the concentration and temperature of solutions have been plotted. Data on the pH and crystallization temperatures of AHOC solutions of various basicity are given depending on the Al2O3 concentration and Al: Cl ratio in the solution. The quality of AHOC has been established to depend on the presence of different forms of aluminum compounds, i.e., monomers, oligomers, and polymers. The degree of polymerization of various hydroxycomplexes present in the AHOC solution has been estimated. The effect of the polymeric component on the density, viscosity, and crystallization temperature of AHOC solutions of various basicity has been revealed.
TL;DR: In this paper, the influence of Nb2O5 on viscosity of oxide-fluoride melts was investigated using a vibration viscosimetry method in the range 1523-1873 K.
Abstract: Influence of Nb2O5 on viscosity of the CaF2-based and CaF2-30% Al2O3-based melts was investigated using a vibration viscosimetry method in the range 1523–1873 K. It is found that viscosity of the melts rise and the crystallization range shifts to lower temperatures as the Nb2O5 concentration increases from 0 to 25 wt %. The activation energy of viscous flow increases from 34 to 110 kJ mol−1 and from 56 to 148 kJ mol−1 for the CaF2-based and CaF2-30% Al2O3-based melts, respectively. The obtained data indicate the complexing behavior of niobium in the oxide-fluoride melts.
TL;DR: Based on an analysis of gravity-centrifuge methods of mineral concentration and ways of the enhancement of their performance, a high-efficiency environmentally appropriate and resource-saving technology of separation of loose mixtures of minerals has been developed as mentioned in this paper.
Abstract: Based on an analysis of gravity-centrifuge methods of mineral concentration and ways of the enhancement of their performance, a high-efficiency environmentally appropriate and resource-saving technology of separation of loose mixtures of minerals has been developed. The method suggested can be used in the building, metallurgical, and mining industries.
TL;DR: In this article, the authors investigated the regularities of interaction of zinc sulfide with the arsenate ion in a sulfuric acid medium and concluded that the limiting stage of interaction is the diffusion of reagents and reaction products through a gas veil consisting of hydrogen sulfide bubbles.
Abstract: Regularities of interaction of zinc sulfide with the arsenate ion in a sulfuric acid medium are investigated. The rates of dissolution of zinc sulfide and precipitation of arsenic increase proportionally to an increase in the concentration of sulfuric acid. However, on attaining the critical value (∼0.1 mol), they vary insignificantly. The experimental activation energies of dissolution of zinc sulfide and precipitation of arsenic are 9.7 and 16.5 kJ/mol, respectively. Based on the investigations carried out, it is concluded that the limiting stage of interaction is the diffusion of reagents and reaction products through a gas veil consisting of hydrogen sulfide bubbles that is formed on the surface of zinc sulfide particles.
TL;DR: In this paper, the corrosion resistance of nanopowders of vanadium, titanium, chromium, and zirconium borides and carbides and of silicon carbide has been investigated in standard electrolytes used for nickel plating.
Abstract: Solubility of nanopowders of vanadium, titanium, chromium, and zirconium borides and carbides and of silicon carbide has been studied in standard electrolytes used for nickel plating. As the objects of the investigation, nanopowders with the contents of the main phase of 92.6–95.3% and an average particle size of 35–62 nm have been used. Their corrosion resistance was estimated depending on the electrolyte acidity, temperature, and duration of the interaction. It has been established that within each group of compounds the nanopowders are close in terms of their corrosion resistance in the electrolytic solutions and are characterized by an unlimited induction period in alkaline media, except for the silicon-carbide nanopowder, which is stable in solutions of any acidity.
TL;DR: In this paper, a foundry-forging module allowing one to obtain a deformed profile of a specified cross section from molten metal in a continuous mode is developed and fabricated.
Abstract: A foundry-forging module allowing one to obtain a deformed profile of a specified cross section from molten metal in a continuous mode is developed and fabricated. The data of metallography investigations of continuously cast deformed blanks (CCDB) from technical copper and their comparison with structures of cast test samples are given. The results of estimation of the dimensional geometric accuracy of the CCDB samples are presented.