Extractive Metallurgy of Heavy Nonferrous Metals
Pashkeev I.Yu., Vlasov V.N. To the problem of phase equilibrium in PbO–SiO2 system
High-temperature phase equilibrium in the PbO–SiO2 system was studied in the concentration range from 60 to 75 % (mol.) SiO2. Available literature data on phase equilibrium in the system and component activities in the liquid melt were generalized. Compatible dependencies, which describe the thermodynamic properties of the melt and solid phases of the system, were derived. A high-temperature range of the PbO–SiO2 phase diagram in concentration range from 0 to 100 % (mol.) SiO2 was plotted.
Katkov S.G., Naboichenko S.S. On the possibility of using nickel nis matte for cementation of copper
The kinetics of copper cementation on nickel and nis matte was studied under the identical hydrodynamic conditions using the rotating disc specimen procedure. The effect of individual parameters was revealed, values of activation energy and experimental velocity constant were calculated, and generalized kinetic conditions were obtained. Retarded copper cementation on nis matte is caused by formation of sulfide films on the specimen surface. The effect of size, metallization extent, nis matte consumption was studied; the process parameters to allow deposition up to 98-99 % copper out of process solutions are suggested.
Donskikh D.K., Zaitsev V.Ya., Kirillin I.I., Fedorov A.N., Bystrov V.P., Dityatovsky L.I., Donskikh K.D. Organization and mastering of antimony production at the Sakha-Ural Antimony Plant
The Sakha-Ural Antimony Plant (Svetly settlement, Orenburg region) for gold-antimony sulfide concentrate processing with production of metal antimony of commercial grade was put into operation in 1996. The Vanyukov process that provides sublimation of volatile components, collection of precious metals in small amount of the metal alloy, and production of free-running slag with minimum content of precious elements was used as a major method of a fundamentally new process flowsheet of the antimony production. Concentrate melting is carried out at T = 250-1300 ° C for slag of the following content (%): 21—25 Fе, 36—42 SiO2, 7—12 CaO. Sublimates contain (%) 92—96 Sb2O3, 0,2—0,3 Fe2O3, 0,2—0,8 S, 0,6—1,0 As, 0,5—1,5 SiO2. Reduction melting of the sublimates with producing rough antimony and its subsequent fire refining is carried out according to the well-proven technology.
Varnek V.A., Sokolov V.V., Diakov V.E. The effect of heat treatment on the state of tin in slags
The state of tin in tin (II) silicate and tin-rich electric-furnace slags fired without air supply at temperatures up to 600—800 ° C for 1 h was studied by Mőssbauer spectroscopy in combination with X-ray analysis and IR-spectroscopy. The nature of phase transformations in the silicate and slags is shown to appear in different ways. Tin silicate disproportions and forms metal tin and tin dioxide, and tin in slags passes out of a glass-like phase into the crystalline one of supposedly pyroxene type. At higher firing temperatures (900, 1000 ° C), this phase disappears, and the heat treatment products reveal metal and silicate tin.
Katkov O.M. Mechanisms of reduction of quartzite in the crucible of an arc furnace
Mechanisms to reduce silica during melting quartzite as well as the causes of losses and the conditions to cut them are made more precise on the basis of studying the operation and structure of electric-furnace reaction crucible for melting silicon. Obtained by computer model experiment and discussed in [1], conclusions on this question are verified in full. Recommendations for commercial melting to raise low process factors when reducing quartzite in arc furnace are made more precise.
Extractive metallurgy of less-common metals
Drobot D.V., Belyaev A.V., Kutvitsky V.A., Rysev A.P. Development of unified X-ray fluorescent analysis to determine rhenium content in multicomponent oxide compositions
A procedure to prepare rhenium-containing glass-like reference specimens on the basis of bismuth and boron oxides is proposed. The glasses produced were studied by X-ray fluorescent analysis and routine spectrophotometric thiocyanate analysis. The results make it possible to determine rhenium in oxide mixtures in the range of its content 0,01-10 % with Sr = 0,03.
Kulifeev V.K., Myakisheva L.V., Derevyanko A.D. To the problem of stability of lithium orthoniobate
The thermodynamic properties of lithium orthoniobate were calculated using approximate methods and the experimental data. Thermodynamic stability of lithium orthoniobate was determined in the following acid solutions: H2SO4, HCl, HNO3, HBr, HI. The kinetic dependences during the decomposition by acids were registered. Apparent activation energies for HCl, HNO3 and H2SO4, being equal accordingly 16,3; 20,4 and 23,7 kJ/mol, were calculated.
Casting Production
Semyonov K.G., Fochenkov B.A. On the quality of BrAZh 9–4 bronze smelt when melting in induction furnace with unidirectional metal motion in the channels
Studies of gas content and nonmetallic inclusions in aluminum bronze BrAZh 9-4 were carried out in channel-type induction furnaces with unidirectional metal motion (UMM) in the channels (with units of UMM). Impurities in the metal are shown to be unchanged in comparison with the furnaces of the conventional channel geometry.
Gerasimov S.P. Practice of manufacturing a large-size artistic shell-mold casting
The paper reports the manufacture of casting sculpture describing a standing man in actual size. The sculpture is cast in parts using investment casting. The assembled parts were decoratively welded along the junction lines. The advantages of the method used are noted.
Metal Forming
Parfenov D.Yu., Mochalov N.A., Galkin A.M. Study of rheological properties of Cu–Ni alloys
Results of plastometric studies of Cu–Ni alloys in the range of speeds V= 0,1-10,0 с- 1 and temperatures T = 700-900 ° C are given in the paper. Fluidity curves are treated by statistical methods and described by polynomials of 4th order. Approximation coefficients for fluidity curves are calculated, and ductility diagrams for MNZh 5-1 and MN-10 alloys are plotted. The search of the range of maximum ductility is carried out by simplex-planning method. The ranges of treating these alloys as applied to hot shaping processes are determined.
Samusev S.V., Shcherba V.N., Ovechkin V.V., Spichak M.G., Senchikhin M.S. Distinctive features of tube and shape forming in roll-bending machines
The distinctive features of tube and shape forming in roll machines are studied on the basis of contact interaction of a billet and the shaping tool. Dependencies of contacting surface change against tool parameters, billet shape and bending pathways are considered. Main defects during the forming are determined, and a mechanism of their appearance is proposed. Specimens of car wheel treads are produced.
Mochalov N.A., Orlinsky P.E. The effect of annealing and etching parameters on the quality of brass strip surface
An analysis of total causes concerning the formation of copper-plated zones on the rolled brass surface after annealing and etching is carried out. Mechanisms of dezincification of a strip of copper-zinc alloys with more than 25 % zinc during annealing with no protective atmosphere and local precipitation of cementing copper during etching in the zones with the highest extent of dezincification are considered. Methods to prevent the formation of copperization of brass articles during their production are proposed.
Physical Metallurgy and Heat Treatment
Pikunov M.V., Piletskaya E.G. To the problem of modeling of non-equilibrium crystallization
There has been investigated the dependence of interaction coefficient estimating non-equilibrium crystallization of alloys on cooling velocity and dendritic cell size. Mathematical expressions describing the relation between these parameters for Al-Zn alloys are obtained.
Marvina L.A., Marvin V.B. On the criterion of stability of grain structure in an alloy that contains particles under the conditions of secondary recrystallization
Physical conditions that determine retardation of migrating grain boundaries (GB) in dispersion-hardened alloys (DHA) during isothermal annealing were analyzed. It is noted that the interaction of migrating grain boundaries with the particles causes the existence of two situations only: combined migration of the GBs and particles at particle velocity (the greatest possible value of which is V) or separation of GB away from the particles. The physically correct condition of the DHA grain structure stability is similar to the condition of GB–particle complex migration: V ³ VGB, where VGB is the velocity of the particles-free GB zone movement. The obtained condition makes it possible to qualitatively explain the effect of particle mobility, kinetic conditions, and testing temperature, known from experiments, on the grain structure stability. It is noted that the prognosis of the grain structure stability of dispersion-hardened alloys during the secondary recrystallization under different temperature-time conditions can be made on the basis of the developed concepts.
Powder Materials and Coatings
Kanunnikova O.M., Gilmutdinov F.Z., Korolev D.A., Elsukov E.P., Bryansky V.Y. Fe1-xMx (M=Sn, Si) powders surface structure
Fe1-xSnx (x = 3,2 - 55 at. %) and Fe1-xSix (x = 15 - 50 at. %) powders were studied by X-ray photoelectron spectroscopy. Samples were mechanically reduced in the ball planetary mill. Medium size of powder particles was 4 m m for Fe1-xSnx and 2 m m for Fe1-xSix. It has been established that surface chemical composition of powders particles differs from that of bulk and posses a complex layered structure. Forming mechanism of this surface layer is discussed.
Corrosion and metal protection
Timoshenko A.V., Buldygin A.V. Microplasma oxidation of V95 alloy in pulsed operation
The effect of pulsed operation on the parameters of breakdown path and coating properties is studied during microplasma oxidation. It is shown that compared to the coatings produced at variable polar conditions, these of higher microhardness can be produced under the pulsed operation at the cost of lesser time period of the breakdown path existence and higher pulse power. On the basis of the experimental data, it is possible to speak about the mechanism of spark discharge development different from the variable polar conditions.
Heat Engineering and Environment Protection in Metallurgy
Lisienko V.G., Kazyaev M.D., Loshkarev N.B., Markin V.P., Saveliev V.A. An analysis of heat operation of electric furnaces for treatment of titanium and aluminum alloys
A balance thermotechnical study was carried out for five different types of heating and melting furnaces for titanium and aluminum alloys. Thermal efficiency, losses of heat conduction through the brickwork, by radiation through open window as well as with filtered air are determined. Major measures are recommended to improve the thermal operation of furnaces. Thermotechnical parameters of furnaces and specific cost expenditures for heating the furnaces during the conversion them to natural gas were analyzed by the rapid method suggested. The current price level for electric power and natural gas causes a high level of cost efficiency of such a conversion, and comparative disadvantages of the gas furnaces (as applied to heating of titanium alloys as well) can be mainly compensated by using the modern methods and heating networks.
Chronicle
To the 100th anniversary of Aleksandr Nikolaevich Krestovnikov
