Search results for " metallurgy"
showing 10 items of 97 documents
Cadmium Recovery from Spent Ni-Cd Batteries: A Brief Review
2021
The significant increase in the demand for efficient electric energy storage during the past decade has promoted an increase in the production and use of Cd-containing batteries. On the one hand, the amount of toxic Cd-containing used batteries is growing, while on the other hand, Cd is on a list of critical raw materials (for Europe). Both of these factors call for the development of effective technology for Cd recovery from spent batteries. The present paper is aimed at providing a short review of the recent progress in Cd recovery from spent batteries. Statistical data from the past decade on the source of Cd, its global production, and Ni-Cd battery recycling are given in the introducti…
Flotation with sedimentation: Steady states and numerical simulation of transient operation
2020
Abstract A spatially one-dimensional model of the hydrodynamics of a flotation column is based on one continuous phase, the fluid, and two disperse phases: the aggregates, that is, bubbles with attached hydrophobic valuable particles, and the solid particles that form the gangue. A common feed inlet for slurry mixture and gas is considered and the bubbles are assumed to be fully aggregated with hydrophobic particles as they enter the column. The conservation law of the three phases yields a model expressed as a system of partial differential equations where the nonlinear constitutive flux functions come from the drift-flux and solids-flux theories. In addition, the total flux functions are …
Influence on the macrosegregation of binary metallic alloys by thermoelectromagnetic convection and electromagnetic stirring combination
2014
International audience; Influence of a slowly rotating 0.5 T transverse magnetic field on the directionally solidified metallic alloy has been experimentally studied in this work. Main idea is to study an influence on the melt flow and material structure caused by the simultaneous electromagnetic stirring and thermoelectromagnetic convection with comparable magnitudes. Electromagnetic stirring and thermoelectromagnetic convection intensities have been estimated analytically to find optimal experimental parameters. It is experimentally demonstrated that with such an interaction it is possible to modify component macrosegregation of Sn-10 wt% Pb alloy. Helical macrosegregation within cylindri…
Mechanically Activated SHS Reaction in the Fe-Al System: In Situ Time Resolved Diffraction Using Synchrotron Radiation
1998
The Mechanical Activation Self propagating High temperature Synthesis (M.A.S.H.S.) processing is a new way to produce nanocrystalline iron aluminide intermetallic compounds. This process is maily the combination of two steps ; in the one hand, a mechanical activation where the Fe - Al powder mixture was milled during a short time at given energy and frequency of shocks and in the other hand, a Self propagating High temperature Synthesis (S.H.S.) reaction, for which the exothermicity of the Fe + Al reaction is used. This fast propagated MASHS reaction has been in -situ investigated using the Time Resolved X - Ray Diffraction (TRXRD) using a X - ray synchrotron beam and an infrared thermograp…
Experimental investigation of low-frequency pulsed Lorentz force influence on the motion of Galinstan melt
2016
Abstract The paper presents the results of the numerical and physical experiments, aimed at assessing the influence of pulsed force of electromagnetic field on the melt motion and the fluid velocities. The experiment was performed on the eutectic alloy Galinstan in the cylindrical volume, where an ultrasonic Doppler velocimeter was employed for velocity measurements under conditions of pulsed and steady EM field application. A numerical simulation of the melt flow, forced by the steady EM force, involved a 2D axisymmetric model. The k-e turbulence model was used to obtain the information about the melt velocities. The verification of the numerical model was carried out for the steady case. …
Mechanical properties and microstructural study of homogeneous and heterogeneous laser welds in α, β,and α + β titanium alloys
2018
International audience; Heterogeneous welding has been investigated for three different couples of titanium alloys: α/α + β, α/β,andα + β/β. Plates of 100 × 60 mm and 1.6 or 1.8 mm thick were welded with a Yb:YAG laser. Tensile tests show that the resistance of the heterogeneous welded specimens was generally controlled by those of the weakest material except for the α + β/β where the ultimate tensile strength was approximately equal to the average value of both materials. In every case, the elongation of the welded sample was found to be smaller than that of the base metals. The rupture generally took place outside the weld metal and was found to be most of the time located in the alloy ha…
What explains the resilience of SMEs? Ambidexterity capability and strategic consistency
2020
Abstract The ability to be resilient, to recover and bounce back when confronted with a threatening and stressful external event, such as the most recent global economic crisis, is an important issue for strategic management research, particularly for small and medium-sized enterprises (SMEs). Research studies on firm level antecedents of resilience offer contradictory propositions, some of which stress the need for experimentation, while others suggest focusing on reliability. To disentangle this controversy and face this gap, our study proposes that for SMEs to achieve resilience, it is necessary that these companies are able to efficiently respond to the changing environments through amb…
Determination of transport and kinetic properties in self-propagating high-temperature synthesis
2007
International audience; Exothermic reactions in solid powders are analyzed using the usual macroscopic modeling based on the heat transfer equation coupled to an Arrhenius type of dynamics. This problem have important applications in the synthesis of intermetallics and ceramic materials which occur when a high temperature reaction wave propagates throughout the system. Understanding the mechanism of such processes are thus crucial in mastering real laboratory experiments. We first analyze the model, both theoretically and numerically, for a set of representative parameters. We then use traditional data analyses procedures to estimate from the temperature profiles the same set of representat…
Combustion synthesis of MoSi2 and MoSi2–Mo5Si3 composites: Multilayer modeling and control of the microstructure
2010
International audience; In this work, we present a multilayer modeling for the formation of molybdenum silicides in the exothermic reaction between Mo and Si under the influence of a temperature pulse. The heating rate can either be a well-controlled ramp or be generated spontaneously by the propagation of a combustion synthesis front. The model addresses the specific situation above the melting point of silicon and describes the solid–liquid reaction taking place in a single representative particle of molybdenum surrounded by the melt of silicon. We obtain a set of kinetic equations for the propagation of the interfaces between the different layers (Mo/Mo5Si3 and Mo5Si3/MoSi2) in the solid…