Extractive metallurgy of nonferrous metals
Abramov A.S., Khrapunov V.E., Isakova R.A., Zhunusova G.Zh., Trebukhov S.A., Sadvakasov D.A. Evaporation of mercury through porous layers of neutral substance at reduced pressure
Diffusion of mercury vapors was studied experimentally at 200 ° C and 13,3 kPa through the air, silicon-oxide layers of size from (–0,063+0,05) to (–0,2+0,16) mm, aluminum and iron oxides of (–0,063+0,05) mm in size and 0,442- 0,807 in porosity. Diffusion coefficient through the air was 25,9× 10–5 m2/s. The effective diffusion coefficient through the oxide layers was (5,14¸ ¸ 11,2)× 10–5 m2/s, being increased with growth of porosity and mean size of pores which was calculated on the basis of mean sizes of particles and porosity. The mechanisms of Knudsen gas flow are observed with mean pore size up to 0,1 mm, and they are also observed with greater pore sizes when the layer consists of fine-dispersed particles.
Natorkhin M.I., Volkov L.V. Cementation clearing of lead chloride solutions of silver and copper by means of structured sponges
A possibility of sedimentation of silver and copper from the solution of chloride leaching by cementation of lead was investigated. The conditions to form structured lead sponges that have extremely developed surface to ensure effective extraction of silver and copper are shown. The methods of determination of visible sponge area have been offered.
Sin’ko A.V., Belousova S.V. Investigation of the mechanism of copper cementation by reagent nickel powder
The cementation process was investigated to reveal the mechanism of electrochemical replacement of copper by reacting nickel powder. Microscopic and microprobe X-ray analysis of the cementation products extracted from the industrial apparatuses found the cementation process to proceed not all the surface of Ni-powder but only on its active centers the potential of which is higher then the nickel ionization potential (18,15 eV); as to finely ground powders, copper sedimentation takes place mainly on one crystallization center and only in single instances this does on two or three centers; there are no diffusion processes except for diffusion of copper cations out of the depth of the electrolyte to the cathode area and through double electrical layer; copper is extracted as an independent phase in the form of self-growing dendrites.
Gurevich R.A., Balmaev B.G., Lainer Yu.A., Yampurov M.L. A study of density and viscosity of aluminum sulfate solutions
The work has investigated a dependence of density and viscosity of the solutions produced by leaching of alumina-containing burnt rock by sulfuric acid within concentrations of 56,6–146,88 g/l Al2O3 and in the temperature range of 25–95 ° C. Equations were drawn to describe the temperature and concentration dependence of density. It was found that changes in the structure of aluminum sulfate solutions when rising to higher concentrations in the range of 95 g/l Al2O3. Activation energy of viscous flow has been calculated; their values are evidence of the structural changes in the solutions.
Metallurgy of less-common and precious metals
Medvedev A.S., Bogatyryova E.V. Decomposition of wolframite concentrates by NaOH solution over a part of waste cake
The additive effect of nuclei of crystallization centers in the solid reaction products of interacting wolframite concentrates with alkaline solutions for extraction of wolfram into the solution was experimentally verified. Based on the results obtained, a process flowsheet of decomposition of wolframite concentrates by alkaline solutions including low-grade ones has been proposed.
Ushakov O.S., Kalashnikov A.L., Matyukha V.A., Smagin A.A., Ushakova Т.V., Kozlova R.D. Investigation of tellurium hexafluoride hydrolysis products
Behavior and chemical forms of the products of TeF6 to water interaction were investigated during their thermal decomposition within the temperature range of 293–1173 K. Composition and properties of starting, intermediate and final products were studied by chemical analysis, IR-spectroscopy and thermogravimetric analysis during their thermal decomposition. Fluorotelluric acids were found to be formed during concentration by evaporation of the solution with hydrolysis products. For example, at T = 463 K, residuum is glassy crystals that contain pentafluorotelluric acid HOTeF5. When heating in the air to 873 K, its evaporation and partial dissociation with formation of TeO2 oxide take place. Nitric acid processing of the solution with hydrolysis products followed by their concentration by evaporation results in formation of TeO3 at 593 K and that of TeO2 at 713 K. High-pure tellurium is formed during the following reduction of TeO2 by hydrogen.
Khatin G.D., Bukin V.I., Sitdikova Yu.S. Gallium extraction from alkaline solutions by N-(2-hydroxy-5-nonylbenzyl)-b ,b -dihydroxyethylamine
Extraction of gallium and aluminum from NaOH solution by N-(2-hydroxy-5-nonylbenzyl)-b ,b -dihydroxyethylamine (NBEA) has been studied. Based on the data on interphase distribution of gallium, IR spectroscopy and calculation of possible structures of extracted complex, the composition and structure of extracted gallium complex (RGa(OH)2) were determined by the methods of molecular mechanics. An equation of extraction of gallium and aluminum by NBEA from alkaline solutions was proposed. Effectiveness of NBEA was shown for extraction of gallium in a wide range of alkaline concentrations (EGa ~ 94÷99 % at CNaOH ~ 0,1¸ 5,0 mole/l). Extraction of gallium from aluminum-containing solutions has been studied. A possibility of making use of NBEA for extraction of gallium from recycle solutions of alumina production process was shown. For example, gallium can be extracted from model Bayer solutions (CGa ~ 0,3 g/l, CAl ~ 30 g/l, CNaOH ~ 3 mole/l) to the amount of 20- 58 % with its complete separation from aluminum at the re-extraction stage.
Casting production
Znamensky L.G. Activation of soluble silicate glue for investment casting by nanosecond electromagnetic impulses
Application of nanosecond electromagnetic impulses (NEMI) was considered for activation of sodium silicate glue in the precision molding. A drop in viscosity and specific electric resistance and a rise in wetting and adhesive ability of sodium silicate binder in the field of NEMI were found. Based on the results obtained, the effective process of preparation of sodium silicate binder has been developed to ensure increasing quality of manufacture of ceramic forms and decreasing the bronze and brass art investment casting rejects.
Metal Forming
Solomonov K.N., Krutov A.V. Modeling of material plastic yielding
The article reviews the last developments in the field of mathematical, computer, geometric, physical modeling of metal plastic yielding, in particular in the aluminum workpiece die forming and pressing processes. The models taken and their computer realization are described as different program complexes. A great attention is paid to consideration of program packages being based on the finite-element method. Geometric modeling allowing observing the task solution on the display is given as one of the promising trends. A comparison of different approaches is given and their advantages and disadvantages are noted.
Physical Metallurgy and Heat Treatment
Agalakov V.V., Pushkaryov S.Yu., Nigmatullina E.S. Application of magnesium alloys in the motor-car industry
The most intensive growth of consumption of cast magnesium alloys can be observed in the automobile industry (at present the branch uses about 90 % of the alloys produced). This is caused by the fact that abroad the problems of reducing car weight become more and more urgent. Application of light construction materials, especially magnesium having the least density (1,74 g/cm3), is one of the main solutions of the problem. By now magnesium parts are applied almost in all parts of a car: engine, transmission, body, passenger compartment. In the course of car operation the magnesium parts work in different conditions, therefore different demands are made to mechanical properties to each of them. These demands are deciding in the choice of the magnesium alloy grade. At present four alloy grades are used for pressure die casting in production quantities but none of the alloy compositions conform in full the requirements in creep resistance at the elevated temperatures.
Dedov N.V., Savchenko N.L., Korolyov P.V., Melnikov A.G., Kul’kov S.N. Wear resistance of ceramic materials on the basis of ZrO2
Using light and scanning electron microscopy the structures formed on the ZrO2 + 3 % mol. Y2O3 friction surface when its sliding on cast high-speed steel have been studied. The tests were carried out according to the “disc–pin” scheme. The slip velocity was 9,4 m/s and loading was 1, 5 and 10 MPa. Friction of ceramics over steel under the cited conditions is accompanied by formation of a system of cracks over the surface. Their quasiperiodic position being perpendicular to the sliding direction is the characteristic of the structures. Average distance (quasiperiod) between transverse cracks is several tens of micrometers. Under all conditions of friction, a transfer layer is formed which is as a result of transfer on it of material of steel rider and its following oxidation at the cost of high temperatures developing in the contact zone. Intensity of wear and tear of ceramic material was found to correlate with distance between transverse cracks and amount of transfer layer on its surface. Small quantity of transfer layer on the friction surface and formation of the structure with great average distance between cracks and their wide distribution in sizes conform to increased intensity of wear and tear at the average loads (5 MPa).
Belova S.B., Nosov V.K. The effect of hydrogen on ductility and strain resistance of VT30 alloy in tests for compression
Based on the results of compression tests within the temperature range of T = 20¸ 1050 ° C, the features of the effect of hydrogen on ductility and resistance to deformation of VT30 alloy have been studied. In the lower temperature range (20–600 ° C), ductility and resistance to deformation are determined by growth of a volume portion of b -phase and increasing its thermal stability with increasing the hydrogen content. Hardening of the alloy by dissolved hydrogen was noted at the b -range temperatures. At T ³ 600 ° C, polygonization and recrystallization are controlling mechanisms of dynamic softening processes.
Powder Materials and Coatings
Oglezneva S.A. Diamond instrument with the matrix of the “iron-nickel” system
Binder for diamond instrument on the basis of mechanically alloyed steel containing 1 % P and 12 % Ni has been developed. Liquid-phase sintering of the power-saturated binder at T = 850 ° C allows hot pressing or pressure sintering to be eliminated. Using metallography, X-ray and microprobe X-ray analysis, formation of metastable austenite was found in the binder structure. Strain austenite-martensite transformation facilitating solid phase strengthening is observed in the course of friction of diamond instrument with nickel-alloyed iron based concentration-heterogeneous matrix over the abrasive. Specific consumption of diamond determined in the laboratory and working conditions is dependent of the volume of austenite-martensite transformation: the greater it is the lesser the specific consumption of diamonds is.
Maly E.N., Dedov N.V., Solovyov A.I., Kul’kov S.N., Savchenko N.L., Sablina T.Yu., Mel’nikov A.G., Korolyov P.V. Sintering of Y-TZP ceramics using plasma-chemical powders
The articles represents the results of studying microstructure, phase composition, and mechanical properties of ceramics on the basis of Y-TZP produced by vacuum sintering in a wide range of temperatures and holding time periods of powders of ZrO2 + 3 mol. % Y2O3 produced by decomposition of water solution of Zr, Y nitrates in the plasma of HF-discharge. The data produced and the properties of ceramics sintered in the air are compared. It was found that sintering in vacuum allows denser and stronger ceramics to be produced, it having density close to theoretical one at the sintering temperature of 1750 ° C. There are no traces of spontaneous transformation from tetragonal phase into monoclinic one when cooling from the sintering temperature, despite the fact that its average grain size runs up to 4,6 m m. Such material has high strength (up to 1000 MPa) and fracture toughness (up to 15 MPa× m1/2).
Structural Macrokinetics. Self-Propagating High-Temperature Synthesis
Kamynina O.K., Rogachyov A.S., Sychyov A.E., Umarov L.M. Mechanism and dynamics of formation of porous product in wave of self-propagating high-temperature synthesis
Application of rapid video shooting (500 frames/s) allowed one to follow the dynamics of substance transfer in the combustion wave with spatial resolution of ~ 10 m m with the 5 Ti + 3 Si and Ti + C on the basis of titanium powder of PTOM, PTM, and PTS with particles of 80- 200 m m in size taken as an example. The experiments were carried out in argon environment under a pressure of 1 at. It was shown that firstly expansion of the environment then its compression takes place directly behind the front of combustion wave. Dimensions of these zones were determined and dependence of the width of strain range on titanium particle sizes was found. Making use of a dilatometer plant allowed us to estimate the forces arising in the front of combustion wave and resulting in elongating the specimens.
Process control and automation
Lisienko V.G., Tashkinov A.Yu., Nasyirov Ya.A., Klimov M.I., Al’tman P.S., Goncharov A.E. A study of ionization for voltage drop and frequency of drop closings in the course of vacuum arc re-melting of heat-resistant steels
An experiment on vacuum arc remelting of alloyed steel electrode of 380 mm in diameter into an ingot of 465 mm in diameter was carried out at Verkhnaya Salda Metallurgical Production Association. A statistical model of arc voltage drop change has been developed depending on duration of ionization relaxation process. The model proposed can be used for optimal control of the vacuum arc remelting.
Khilay V.V., Karelov S.V., Mamyachenkov S.V., Kirpikov A.S. The convenient mode of calculation of the composite mass balances of ramified flow diagrams is presented in view of reverse materials
Mode of calculation of the mass balances of composite flow diagrams in view of reverse materials. The possibility of fast count of balance is taken into account at a modification of makeup of a feed stock, indexes of extraction on elements, parameters of operations. The advantages in comparison with usually used computer programs are shown.
Economics and Management
Kel’chevskaya N.R., Srogovich M.I. New ways of interaction between the Higher School and metallurgical industry in XXI century
Under the modern conditions of severe competition, it is insufficient for any organization to use standard managerial set of instruments in order to hold leadership – so named innovative approach and a new concept of management process: “intellectualization of management” should be taken for adding to their arsenal. Its substance is in making use of intellectual instruments of management for comprehensive development of its intellectual potential. In addition it is necessary to pay a special attention to the human component of the intellectual capital. The developed procedure on interaction of the metallurgical industry and the Higher School in specialist training facilitates this taking the trends of development of the branch into account. Its aim is to bring the requirements of enterprises to conformity with the human resources and quality of their training in the institutes of higher education. Metallurgical enterprises of Sverdlovsk District and Russia were a subject of this investigation.
