Light Metals Research Papers - Academia.edu (original) (raw)

The solidification behavior of liquid metal in a container under rapid cooling process is one of the major concerns to be analyzed. In order to analyze its fundamental behavior, a three- dimensional (3D) fluid dynamics simulation was... more

The solidification behavior of liquid metal in a container under rapid cooling process is one of the major concerns to be analyzed. In order to analyze its fundamental behavior, a three- dimensional (3D) fluid dynamics simulation was developed using a particle-based method, known as the smoothed particle hydrodynamics (SPH) method. Governing equations that determine the fluid motion and heat transfer involving phase change process are solved by discretizing their gradient and Laplacian term with the moving particles and calculating the interaction with its neighboring particles. The results demonstrate that the SPH mehod can successfully reproduce the behavior and defect prediction of liquid metal solidification process.

In the present work Al-12.4Si Alloy with and without Zirconium(Zr) Addition has been synthesized though Gravity die-casting process. The microstructure evolution and mechanical properties of eutectic Al-12.4Si alloy with various... more

In the present work Al-12.4Si Alloy with and without Zirconium(Zr) Addition has been synthesized though Gravity die-casting process. The microstructure evolution and mechanical properties of eutectic Al-12.4Si alloy with various proportion Zr additions were investigated. The cast sample was characterized by optical microscopy(OM), and X-ray diffraction(XRD).The microstructal observation shows that the primary Si crystal was significantly modified from coarse polygonal shape to fine blocky shape with smooth edges and corners, and eutectic Si phases are modified from coarse platelet-like/ needle-like structure to fine fibrous structure. The mechanical properties were investigated by tensile and hardness test with various concentration (0.1,0.3,and 0.5wt%) of Zirconium. It was found that the ultimate tensile strength (UTS) and % elongation is increased with increasing the modifying and refining element as compare to base alloy, due to decreasing the size and changing the overall morphology on primary and eutectic Si crystal. Bulk hardness was also improved for modified structure as compare to base structure.

In this paper, we applied an improved Smoothing Particle Hydrodynamics (SPH) method by using gradient kernel renormalization in three-dimensional cases. The purpose of gradient kernel renormalization is to improve the accuracy of... more

In this paper, we applied an improved Smoothing Particle Hydrodynamics (SPH) method by using gradient kernel renormalization in three-dimensional cases. The purpose of gradient kernel renormalization is to improve the accuracy of numerical simulation by improving gradient kernel approximation. This method is implemented for simulating free surface flows, in particular dam break case with rigid ball structures and the propagation of waves towards a slope in a rectangular tank.

The paper combines the experience of foundry men with research of the theory and prediction of porosity formation. The influence of flux treatment was determined and also the influence of strontium and antimony refining of AlSi7Mg0.3... more

The paper combines the experience of foundry men with research of the theory and prediction of porosity formation. The influence of flux treatment was determined and also the influence of strontium and antimony refining of AlSi7Mg0.3 alloy on the porosity formation was ...

Dissolution of alumina in industrial aluminium cells is a complicated process, not least because it involves formation of agglomerates, and it involves mass- and heat transfer phenomena taking place simultaneously. In the present study,... more

Dissolution of alumina in industrial aluminium cells is a complicated process, not least because it involves formation of agglomerates, and it involves mass- and heat transfer phenomena taking place simultaneously. In the present study, the diffusion coefficient of alumina in cryolitic melts was measured using a rotating alumina disc. It was found that the temperature dependence of the diffusion coefficient is relatively large. The enthalpies for heating of alumina, conversion, and dissolution are summarised. The addition of 1 wt% alumina causes adiabatic cooling of typically 10–12 °C in a normal industrial bath. The dissolution can be regarded as being purely mass transfer controlled, since the heat required for dissolution only brings about 1 °C temperature drop from the bath bulk to the alumina surface. The bath at the alumina surface is saturated in alumina and has a lower liquidus temperature than the bulk. Alumina dissolution can, therefore, take place in a supercooled bath.

In this study, an experimental, metallographic method for determining strain distribution in a cold extruded aluminum gear-like element, based on the dependence of recrystallized grain size on prior deformation, was devised in order to... more

In this study, an experimental, metallographic method for determining strain distribution in a cold extruded aluminum gear-like element, based on the dependence of recrystallized grain size on prior deformation, was devised in order to overcome design problems in manufacturing of complex parts where critical values of strain and stress could cause a fracture. The method was applied on a 99.5% aluminum bar subjected to cold, radial extrusion, in order to produce complex gear-like element. To reveal the strain and stress distribution in specimens, the calibration and flow curves were first obtained by uniaxial compression (Rastegaev test). Afterwards, the grain size in different parts of the gear section was examined, the strain and stress distributions were calculated, and the results were confirmed by microhardness measurements. It was found that grain size, strain, stress, and microhardness considerably differed throughout the cross-section of the gear. The coarsest grain, and thus...

OBJECTIVES: This study assessed the source contributions to the mass concentrations of fine particles (PM2.5) in personal exposures and in residential indoor, residential outdoor, and workplace indoor microenvironments of the nonsmoking... more

OBJECTIVES: This study assessed the source contributions to the mass concentrations of fine particles (PM2.5) in personal exposures and in residential indoor, residential outdoor, and workplace indoor microenvironments of the nonsmoking adult population unexposed to environmental tobacco smoke in Helsinki, Finland.METHODS: The elemental composition of 48-hour personal exposure and residential indoor, residential outdoor, and workplace indoor PM2.5 was analyzed by energy-dispersive X-ray fluorescence spectrometry for 76 participants not exposed to environmental tobacco smoke and 102 participating residences with no smoking in Helsinki as a part of the EXPOLIS study. Subsequently, a principal component analysis was used to identify the emission sources of PM2.5-bound elements and black smoke in each microenvironment, and this information was used to identify the corresponding sources in personal exposures. Finally, source reconstruction was done to determine the relative contributions of each source type to the total PM2.5 mass concentrations.RESULTS: Inorganic secondary particles, primary combustion, and soil were the dominant source types for the PM2.5 mass concentration in all the microenvironments and personal exposures. The ratio of the residential indoor-to-outdoor PM2.5 concentration was close to unity, but the corresponding elemental ratios and source contributions varied. Resuspension of soil dust tracked indoors was a much larger contributor to residential and workplace indoor PM2.5 than soil dust to residential outdoor PM2.5. Source contributions to personal PM2.5 exposures were best approximated by data from residential and workplace indoor microenvironments.CONCLUSIONS: Population exposure assessment of PM2.5, based on outdoor fixed-site monitoring, overestimates exposures to outdoor sources like traffic and long-range transport and does not account for the contribution of significant indoor sources.

The aluminum industry is studying ways to increase the efficiency of reduction cells in new and retrofit smelters. Numerical simulation has become a very effective tool for analyzing such complex processes. This paper presents... more

The aluminum industry is studying ways to increase the efficiency of reduction cells in new and retrofit smelters. Numerical simulation has become a very effective tool for analyzing such complex processes. This paper presents magnetohydrodynamic (MHD) simulations of a cell technology case study. A three-dimensional (3-D) model was developed by coupling commercial codes ANSYS and CFX, via in-house programs and customization subroutines. A detailed electromagnetic model was built in ANSYS, which uses Finite Element Method. Steady state and transient MHD flows in the cell were calculated with CFX, which uses Finite Volume Method. Metal and bath were treated as multiphase flow. The homogeneous VOF (Volume of Fluid) model, available in CFX, was used to calculate bath-metal interface in steady state and transient regimes. The transient simulation of the bath-metal interface was used for the study of cell stability.

ABSTRACT Electromagnetic fields can influence the behavior of liquid metals in commercial Ceramic Foam Filters (CFF's). In the present study 9 inch industrial CFF's of high grade with 50 and 80 pores per inch (ppi) have... more

ABSTRACT Electromagnetic fields can influence the behavior of liquid metals in commercial Ceramic Foam Filters (CFF's). In the present study 9 inch industrial CFF's of high grade with 50 and 80 pores per inch (ppi) have been investigated. The main objective was to prime the 9 inch industrial scale CFF's with a standard aluminum casting alloy (3XXX - alloy) by the use of various magnetic field strengths (max. 0.12 T) induced by a coil. The obtained results were compared with reference gravity experiments. The influence of the electromagnetic Lorentz forces on the obtained results was calculated with 2D Finite Element Modeling (FEM) using the COMSOL® software. The fluid flow characteristics inside the CFF were considered and are part of another publication within the group.

We provide a basic method of Smoothed Particle Hydrodynamics (SPH) to simulate liquid droplet with surface tension in three dimensions. Liquid droplet is a simple case for surface tension modeling. Surface tension works only on fluid... more

We provide a basic method of Smoothed Particle Hydrodynamics (SPH) to simulate liquid droplet with surface tension in three dimensions. Liquid droplet is a simple case for surface tension modeling. Surface tension works only on fluid surface. In SPH method, we simply apply the surface tension on the boundary particles of liquid. The particle on the 3D boundary was detected dynamically using Free-Surface Detection algorithm. The normal vector and curvature of the boundary surface were calculated simultaneously with 3D boundary surface reconstruction using Moving Least-Squares (MLS) method. Before the reconstruction, the coordinate system was transformed into a local coordinate system. Afterwards, the surface tension force which depends on curvature of the surface, was calculated and applied on the boundary particles of the droplet. We present the simulation result of droplet motion with gravity force. By using the basic method of SPH for fluid modeling, and a combination of 3D Free-Surface Detection algorithm with MLS method, we can simulate droplet phenomena with expected result.

In this paper the update of directive 67/548/EEC published in Official Journal of the European Union on 16 January 2009 proposes about carcinogenicity of metallic elements is reported and discussed. The main change is represented by the... more

In this paper the update of directive 67/548/EEC published in Official Journal of the European Union on 16 January 2009 proposes about carcinogenicity of metallic elements is reported and discussed. The main change is represented by the classification R49 and R40 of many species of nickel, organic and inorganic, respectively for their water solubility and particles size. Titanium oxide and 3 tin species are in addition classified as R40. Sodium dichromate moved from R49 (in the 22nd update) to R45 (classified as carcinogen, without restriction on the route of exposure). The list of the 31st updates, if combined with previous list, provides detailed and more precise information on the carcinogenicity of metallic elements in relation to different species, suggesting once again the importance of metallic element speciation.

The purpose of the present study was to investigate the effect of different grain refiners’ additions on structure and electrical conductivity of commercially electrically conductive (EC) grade 1370 aluminium alloy. A series of controlled... more

The purpose of the present study was to investigate the effect of different grain refiners’ additions on structure and electrical conductivity of commercially electrically conductive (EC) grade 1370 aluminium alloy. A series of controlled lab scale experiments were carried out by addition of 0.1 wt% Al-5Ti-1B, Al-3Ti-1B, OPTIFINE, TiBloy, and Al-3Ti-0.15C, grain refiners to molten aluminium at 730 ± 5 °C. The macro structural analysis showed that 0.1 wt% of TiBloy, Al-5Ti-1B, Al-3Ti-1B, and OPTIFINE did not grain refine commercial EC grade aluminium. The Al-3Ti-0.15C master alloy showed, however, good grain refining performance, giving an equiaxed structure. Fading effect was observed in the samples grain-refined by Al-3Ti-0.15C master alloy. The electrical conductivity of all the grain-refined samples decreased between 0.02–0.75 ± 0.3% IACS, compared to the reference samples of commercial pure aluminium. However, the electrical conductivity increased slightly by holding the melt, a...

Two innovations presented by the authors recently at ICSOBA conferences allow to very significantly reducing both the cathode and the busbar voltage drop (Dupuis in A new aluminium electrolysis cell busbar network concept, 2015; Dupuis in... more

Two innovations presented by the authors recently at ICSOBA conferences allow to very significantly reducing both the cathode and the busbar voltage drop (Dupuis in A new aluminium electrolysis cell busbar network concept, 2015; Dupuis in New busbar network concepts taking advantage of copper collector bars to reduce Busbar weight and increase cell power efficiency, 2016). This paper combines the usage of those two innovations with the usage of the new anode stub hole design presented at the Aluminiun of Siberia conference (Dupuis in Presentation of a new anode stub hole design reducing the voltage drop of the connection by 50 mV, 2016) to come up with a very low energy consumption cell design.