Upsetting with wall thinning for thick-walled anisotropic cylindrical blanks

The stress and strain state of the blank, the applied force, and the limiting possible shape change are investigated in upsetting with wall thinning for thick-walled anisotropic cylindrical blanks.     

Experimental study of phase equilibria in the systems PbO x -CaO and PbO x -CaO-SiO2

The reported experimental work on the systems PbO _x -CaO and PbO _x -CaO-SiO₂ in air is part of a wider research program that combines experimental and thermodynamic computer modeling techniques to characterize zinc/lead industrial slags. Extensive experimental investigation by high-temperature equilibration and quenching techniques followed by electron probe microanalysis was carried out in the temperature range 640 °C to 1500 °C (913 to 1773 K) and in the composition ranges 0 to 65 mol pct SiO₂ and 0 to 42 mol pct CaO. Liquidus and solidus data were reported for most of the primary phase fields. Liquidus surfaces in the systems CaO-Pb-O and PbO _x -CaO-SiO₂ in air were completely reconstructed. Extensive solid solutions of PbO in α′ dicalcium silicate and Ca₂Pb₃Si₃O₁₁ were measured.     

A reinvestigation of phase equilibria in the system Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>-ZnO

The phase equilibria and liquidus temperatures in the binary SiO₂-ZnO system and in the ternary Al₂O₃-SiO₂-ZnO system at low Al₂O₃ concentrations have been experimentally determined using the equilibration and quenching technique followed by electron probe X-ray microanalysis. In the SiO₂-ZnO system, two binary eutectics involving the congruently melting willemite (Zn₂SiO₄) were found at 1448±5 °C and 0.52±0.01 mole fraction ZnO and at 1502±5 °C and 0.71±0.01 mole fraction ZnO, respectively. The two ternary eutectics involving willemite previously reported in the Al₂O₃-SiO₂-ZnO system were found to be at 1315±5 °C and 1425±25 °C, respectively. The compositions of the eutectics are 0.07, 0.52, and 0.41 and 0.05, 0.28, and 0.67 mole fraction Al₂O₃, SiO₂, and ZnO, respectively. The results of the present investigation are significantly different from the results of previous studies.     

Condensation of a gas-vapor mixture in an electric field

Condensation of a gas-vapor mixture in a direct electric field is discussed in this paper. At a noncondensable gas concentration of 5%, an approximately two-fold increase in the condensed liquid amount is obtained. The condensation process enhancement is explained by the cooperative effect of the condensate film turbulization and the decrease in the diffusion resistance of the noncondensable gas layer in an electric field. The obtained results can be used for the design of electrohydrodynamic generators and compact vapor condensers.     

Experimental and thermodynamic modeling study of phase equilibria in the PbO–NiO–SiO2 system

An integrated experimental and thermodynamic modeling investigation of the phase equilibria in the PbO–NiO–SiO₂ system in air and also in equilibrium with liquid metal has been undertaken to better characterize the chemical reactions taking place in the Ni-containing Pb processing slags. New experimental phase equilibria data at 720°C–1740°C were obtained for this system using high-temperature equilibration of synthetic mixtures with predetermined compositions in sealed silica ampoules or in Au/Pt–Ir foils, a rapid quenching technique, and electron probe x-ray microanalysis of the equilibrated phase compositions. Phase equilibria and liquidus isotherms in the quartz/tridymite/cristobalite (SiO₂), olivine (Ni₂SiO₄), monoxide (NiO), Ni-barysilite (Pb₈NiSi₆O₂₁), massicot (PbO), and di-lead silicate (Pb₂SiO₄) primary phase fields were revealed and the extent of the high-SiO₂ two-liquid immiscibility gap in equilibrium with cristobalite was determined. New experimental data were used in the development of a thermodynamic database describing this ternary system. Also, modeling revision of the NiO–SiO₂ binary system was conducted, resulting in a smaller miscibility gap in ternary systems that was closer to the experimental results.     

Experimental Investigation of Gas/Matte/Spinel Equilibria in the Cu-Fe-O-S System at 1473 K (1200 °C) and <Emphasis Type="Italic">P</Emphasis>(SO<Subscript>2</Subscript>) = 0.25 atm

The Cu-Fe-O-S system is the key system for the characterisation of the phase chemistry in high-temperature copper making processes. An experimental study was undertaken to investigate the gas/matte/spinel equilibria in the Cu-Fe-O-S system at 1473 K (1200 °C), P(SO₂) = 0.25 atm, and a range of oxygen partial pressures. The experimental methodology involved high temperature equilibration using a primary phase substrate technique in controlled gas atmospheres (CO/CO₂/SO₂/Ar), rapid quenching of the equilibrated phases, followed by direct measurement of phase compositions using electron probe x-ray microanalysis. Particular attention was given to the analysis of reactions during equilibration and confirmation of the achievement of equilibrium in the present study. The new data provide important information for understanding of the gas/matte/spinel interactions at high temperature and provide an essential foundation for the development of the multicomponent thermodynamic database for copper-containing systems.     

Condensation of a gas-vapor mixture under the conditions of a corona discharge

The experimental data on the condensation of vapor from a gas-vapor mixture in the presence of an electric field are discussed. It is assumed that a corona discharge or, to be more accurate, its accompanying phenomena such as the unipolar charging of the medium and the electric wind, which produces intense mixing both of the medium and the condensate film, is the main factor influencing the intensification of the condensation in an electric field. The criteria of the similarity of the process, among which the main attention is drawn to the “electric” Reynolds number, which characterizes the interaction of the electric field with the medium, are considered. We also discuss the parameters of vapor-air mixtures, such as their density, viscosity, and ion mobility. A simplified method of the generalization of the experimental data on condensation in the presence of an electric field based on the concepts of a corona discharge is proposed.     

Selected Phase Equilibria Studies in the Al2O3–CaO–SiO2 System

The Al₂O₃–CaO–SiO₂ system provides the basis for describing many important chemical processes. Although the system has previously been extensively studied, recent advances in experimental technique have provided the opportunity to obtain accurate liquidus measurements in the low‐silica region at fixed temperatures. The experimental procedures involve equilibration of high‐purity oxide powder mixtures at selected temperatures, rapid quenching, and accurate measurement of phase compositions using electron probe X‐ray microanalysis. The liquidus isotherms have been determined at selected temperatures between 1503 and 1873 K in the anorthite, gehlenite, pseudowollastonite, corundum, CaAl₁₂O₁₉, CaAl₂O₆, lime, Ca₃SiO₃, and Ca₂SiO₄ primary phase fields. The results are compared with currently available thermodynamic model predictions of the phase chemistry.     

A method to estimate mass dispersion in inhomogeneous convective flows

A diffusion-model-based generalizing method for estimating the dispersion of mass in inhomogeneous convective flows is considered. An admissible class of exact solutions, a comparison with which allows one to establish the dispersion coefficient and the error of application of the model in each specific case, has been determined. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 120–123, January–February, 2007.     

Liquidus Temperatures in the “Cu<Subscript>2</Subscript>O”-FeO-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>-CaO-SiO<Subscript>2</Subscript> System at Metallic Copper Saturation,at Fixed Oxygen Partial Pressures,and in Equilibrium with Spinel or Dicalcium Ferrite at 1200 °C and 1250 °C

Calcium ferrite slags, which are represented by the “Cu₂O”-FeO-Fe₂O₃-CaO system at copper saturation, have been applied successfully to existing copper-converting processes. Because of the industrial importance of this system, the characterization of the effects of oxygen partial pressure and silica on the phase equilibria is necessary to improve the control of process parameters, which include fluxing and operating temperatures. In the current study, experimental methods, which use the equilibration/quenching/electron probe X-ray microanalysis (EPMA) techniques with primary phase substrate support, were subsequently developed to incorporate fixed oxygen partial pressure experiments. Experiments were carried out at 1200 °C and 1250 °C both with and without silica additions; both liquidus and solidus data were reported for the primary phase field of spinel and dicalcium ferrite between the oxygen partial pressures of 10^?5.0 and 10^?6.5 atm. The analyzed compositions of the liquid and solid phases are used to construct the phase diagram of the pseudoternary “Cu₂O”-“Fe₂O₃”-CaO system in equilibrium with metallic copper at fixed oxygen partial pressures and with additions of silica. The maximum solubility of silica within the liquid slag phase, prior to dicalcium silicate precipitation, was measured at specific conditions. Two empirical equations used for the calculation of the copper oxide concentration in calcium ferrite slag are evaluated with the new experimental data defined in the current study.