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By Matthias Merzkirch, Volker Schulze, Kay Andre Weidenmann

"Unidirectionally reinforced light weight compounds based on light metals such as the aluminium alloy EN A W-6082 are adequate materials for the future use in transportation means like automobiles and airplanes. Due to the occurring cyclic loads knowledge about the crack growth behaviour of such composites is needed. The investigations at a load ratio of R = 0.18 show that the crack growth rate of the aluminium matrix is reduced if reinforced by spring steel wire with a reinforcing ratio of only about 1 Vol.-%. Additionally, the acoustic emission analysis allows detecting crack growth within the matrix material, crack propagation along the interface wire/matrix and crack closure which could also be determined with the help of a self designed capacitive displacement measuring gauge. The damage behaviour could be verified by metallographic and SEM investigations.IntroductionIn the field of lightweight structures for transportation means the need for light, strong and stiff materials, in particular composite materials, is increasing in order to save resources and costs. Lightweight materials such as aluminium and magnesium alloys are highly efficient candidates to be used in the composite extrusion process [1] which allows for a simple production of unidirectionally reinforced profiles with a large diversity of geometries at low costs. Figure 1 depicts the principle of the composite extrusion process; within the first part of the tool the billet material is split into several strands whereas the middle part of the tool allows the supply of the reinforcing elements. The third part of the tool rejoins the matrix material and the reinforcing elements and defines the final shape of the profile."

Jan 1, 2011

By Bo Jiang, Jiusan Xiao, Hongmin Zhu, Kai Huang, Shuqiang Jiao

Carbothermal selective reduction of simulative titanium slag and various titanium raw materials were presented and SiO2 was found to be partially reduced, forming a series of Fe-Si alloys during the process. Thermodynamic analysis of the selective reduction between TiO2 and SiO2 was performed using HSC 6.0 software, then a series of equilibrium experiments were designed and presented. The activity of Si reduced from SiO2 was affected by the presence of Fe reduced from FeOx and the generation of Fe-Si alloys, promoting the reduction of SiO2 in the whole process. The results of experiment are in great accordance with the calculated data obtained from thermodynamic analysis.

Jan 1, 2016

By G. K. Ruhlandt, C. W. Kim

"A 3-D Finite Element Method program called ""SOLCAST"" has been developed to simulate the casting solidification process. Using the temperature recovery method to evaluate the latent heat of fusion and applying a new combination of the time integration scheme, SOLCAST reduces the computational time significantly compared to an existing commercial FEM program, and produces accurate results comparable to experimental casting results. Prediction of casting shrinkage porosity for A390 aluminum alloy will also be discussed. To make this FEM program useful for foundry engineers, this program was connected to a commercial pre- and post-processor.IntroductionBecause of recently increased competition, foundrymen must produce high quality castings more economically. Therefore, casting solidification analysis prior to casting production is an attractive way to reduce costs and development time.Although the actual casting solidification process is a very complicated phenomena, foundrymen could predict where shrinkage defects would occur based on a transient conduction heat transfer analysis that includes the liberation of latent heat. A numerical analysis is generally required to solve the heat diffusion equation with the latent heat diffusion term, because casting shapes are very complicated and pure materials are rarely used.Different numerical methods have been applied to the casting solidification analysis 1. Among them, a finite difference method 2 and a finite element method (FEM)3 are most commonly used.Each simulation method has one or more basic difficulties which are different for each method. These difficulties are:(1) Modeling casting shapes on a computer.(2) Time consuming computation.(3) Uncertain material properties."

Jan 1, 1986

By J. R. Bhamidipati, Nagy EI-Kaddah

"Over the years, mathematical modeling has been established as a viable tool for design and analysis of melting and solidification processes. Modeling of electromagnetic casting and melting systems involves three coupled problems -- determination of the containment field, the shape of the meniscus, and the temperature field -- which have to be solved simultaneously. One of the difficulties in numerical simulation of these systems is in defining and gridding the solution domain as the meniscus shape of the liquid region is not known a priori. This paper describes a methodology for solving these coupled problems in a two-dimensional electromagnetic containment field. This method is based on the solution of the electromagnetic, free surface dynamic, and heat transfer equations in a fixed domain in computational space by mapping the physical space into an invariant computational space during the search for the equilibrium shape using a variable non-orthogonal coordinate transformation. This approach, also, eliminates the need for regridding the liquid and solid regions during phase change. This methodology is demonstrated for two electromagnetic confinement systems -- the Magnetic Suspension Melting process and the electromagnetic casting of aluminum. The model predictions are in good agreement with available data for these systems. It is suggested that the methodology presented here is likely to provide a useful tool in the design, analysis, and optimization of electromagnetic confinement systems. IntroductionDuring the past decade, mathematical modeling has emerged as a viable tool for the design, analysis, and optimization of casting and melting processes /1-2/. It is generally recognized that the usefulness of modeling to study the interplay between the various process parameters without resorting to extensive experimentation relies heavily on accurate representation of the physical phenomena in these systems. In modeling electromagnetic confinement casting and melting systems, it is important that the model address all aspects of electromagnetic field interaction with the metal, if accurate predictions are to be obtained /3/. The electromagnetic field affects the heat transfer phenomena primarily through joule heating. In addition, the electromagnetic forces play a key role in heat redistribution in the molten pool via melt stirring, and, in confinement systems, support the molten metal pool."

Jan 1, 1994

By Edmundo Manilla, Merete Tangstad, Daniel Davila, Eli Ringdalen

FeMn alloys are typically produced with lumpy ore or sinters. Minara Autlan, the Mexican FeMn producer, is however making Mn-nodules as a raw material for Mn-alloy production. The Mn nodules have been characterized by XRF, XRD, by wet chemical methods and by EPMA. The Mn/Fe ratio is somewhat lower compared to commercial Mn ore on the marked. The basicity of the ore is however close to 1, and additional fluxes may not be used. The Mn-nodules will be in a state of manganosite (MnO), tephroite ((Mn, Ca)2SiO4) and galaxite ((Mn,Mg)Al2O4). This leads to a low melting temperature area. A low porosity and low amount of higher Mn-oxides gives a high thermal strength to the nodules.

Jan 1, 2016

By John J. Dunkley

Recent years have seen the increased use of hydrometallurgy in the smelting and refining of metals. However this is often used as a final refining step, following an initial pyrometallurgical smelting process. Huge amounts of material are produced as melts which have to be cast, comminuted, and taken up into solution or leached. A common method is to granulate the melt and then grind it. In the case of metallic melts this can be difficult or unfeasible due to the ductility of the granulated particles. Water atomisation is capable of replacing the granulation and grinding stages with a single process step that can process in excess of 30tlhour of melt into particles as fine as 50 microns. Applications in operation in Co, Cu, Ni, Ag, Au, Pt and Rh refining are discussed together with potential applications in copper smelting.

Jan 1, 2003

By Selim Coskun

In this study, tungsten matrix composites reinforced with 2 wt% TiC particles were mechanically alloyed (MA?d) for 3h, 6h, 12h and 24h. 1 wt% Ni is used as sintering aid which is added before and after mechanical alloying. Microstructural and phase characterizations of composite powders and sintered samples were carried out via SEM and XRD analyses. Furthermore, density and hardness measurements of as-consolidated and sintered samples were carried out. Additionally, DSC experiments were conducted to investigate the sintering behavior of the MA?d powders.

Jan 1, 2009

By I. Perus, M. Fazarinc, G. Kugler, M. Tercelj

"Ledeburitic tool steels are highly alloyed steels used for specific highly loaded applications but are characterized by low and variable hot workability. In this contribution the importance of selecting the right choice of some essential process parameters, i.e. casting temperature, solidification rate and soaking temperature, needed for improving the intrinsic hot deformability of ledeburitic tool steels, is studied. An inappropriate selection of casting temperature and cooling rate results in precipitation of unusual eutectic carbides that decreases the hot workability, whereas with the selection of appropriate soaking temperature the temperature range of safe hot working can be broadened. For each initial as-cast microstructure individually determined soaking temperature should be selected.IntroductionThe surface cracking during hot deformation of ledeburitic tool steels reduces mechanical properties and their industrial yield. These tool steels have high hardness, wear resistance and high tempering resistance on one hand, and high flow stresses and low hot deformability on the other. Decreased hot deformability of the tool steels is attributed to the type, size, shape, distribution, fraction of eutectic carbides and/or other phases, grain growth, etc. at upper limit while precipitation of secondary carbides and decreased recrystallization rate at lower limit of the safe hot deformation temperature range, [1-6].The occurrence of cracks on most exposed areas of workpiece are related to the areas where similar conditions related to upper and/or lower limit of temperature working range prevail, i.e. areas with accelerated cooling, areas with higher value of accumulated strains where also decreased recrystallization rate with simultaneously presence of higher tensile stresses takes place, furthermore areas of workpiece which are due to combustion conditions in furnace heated to higher temperatures, etc. Thus the areas, where combination of previously mentioned conditions prevails, are more exposed to cracking. This additionally requires that hot deformability of ledeburitic tool steel should be considered as a complex problem. Publications in the literature with regards to hot deformability of tool steels are predominately of a partial nature thus all reasons for unexpected occurrence of cracks are not sufficiently explained in available literature so far. Furthermore modern practice proves that previous processing parameters significantly influence the hot deformability and thus this cannot be considered as a constant value. During heating, soaking and hot deformation various processes take place: decay (decomposition) of carbides, formation of new carbides, dissolution of carbides and of alloying elements, etc. Thus depending on variation of process parameters and chemical composition, that consequently influences the processes related to carbides, shifting of decreased deformability at both limits of temperature working range to higher and/or to lower temperatures can occur, [1-14]."

Jan 1, 2012

By Kazuyuki Kikuta

MMAJ, a govemmental organization in Japan, has carried out a 4 year project for the development of the decontamination and metals recovering technology for the fly ashes from municipal waste incineration. Heavy metals (zinc, lead and copper) are recovered as raw materials for the non-ferrous metals production, without formation of any waste materials to be disposed. More than 500 thousands tonnes a year of fly ashes generation from the municipal waste incineration has been one of the main social issues in Japan, because most of them need to be disposed to the registered areas after decontamination, and occupy 5% of the municipal wastes disposed. The segregation, flotation and chemical process are applied to the treatment of the primary fly ash from municipal waste incineration, and MF (Mitsui-type blast furnace) Process after the chlorine removal to the secondary fly ash. The main results of experiments are -About 90% of heavy metals, zinc, lead and copper, can be recovered from the primary and the secondary fly ashes to the products for the non-ferrous metals production. -Both of the leaching residue from the primary fly ash treatment and the slag from the secondary fly ash treatment can be used as a raw material for the cement production, meaning that the decontamination technology for the ashes without the landfill has been established. -Dioxins in the primary ash can be decomposed satisfactorily, and the dioxins content in the segregation furnace gas is less than O.lng-TEQ/Nm3 without any gas cleaning system

Jan 1, 2003

By Liyuan Chai

The corrosion mechanism of A3 steel induced by chloride ions in the purified water had been investigated with the A C Impedance technique. The results showed that there were another two factors which determined its electrochemical corrosive rate: the electrode potential and coverage ratio of chloride ions on the surface of A3 Steel. The corrosion mechanism of A3 steel in the solution with chloride ions emendation was two steps of electrode process with the rate-determining step of 0,32kFeClFeCle+--¾¾®++.

Jan 1, 2009

By H. Itou, J. M. Toguri, T. Takasu

"Marangoni convection has a large effect on materials processing since it remarkably enhances heat and mass transport near a free interface. To have a better understanding of the behavior of Marangoni convection in molten salts, observation and calculation of the thermal convection in a column held between a pair of Pt disks (2mm in diameter) fixed to hot thermocouples, were carried out.Calculated flow patterns and absolute values of fluid velocity agreed well with the observed results. When the temperatures of both disks were set equal and the height of liquid column was 2.4mm, four vortexes were generated on the longitudinal plane with a typical velocity of 15mm/s . From the calculated isothermal lines, the behavior of the enhanced heat transport was obvious; fluid heated at the disks was conveyed to the free surface and the cooled fluid at the surface was conveyed to the inner region. Increase in the height of column and/or increase in the absolute value of applied temperature difference lead to increase in fluid velocity lineally in this calculation range.IntroductionIn the processing of many materials, fluid flow of melts has a large effect on refining capabilities and on the characteristics of the produced material. Marangoni convection is generated when a spatial gradient of interfacial tension exists on the free interface due to differences in temperature and/or concentration. This promotes heat and mass transfer locally near the interface.For example, Marangoni convection which are created following the dissolution of interfacially active materials, increases the local corrosion rate of refractories (1-3). In absorption and discharge of oxygen and/or nitrogen in a molten metal, the effective reaction rate of the gas components through the gas-liquid interface increases (4-7). Also in crystal growth, the distribution of defects and impurities in the crystal is affected and this can alter its quality (8-11 ). The temperature distribution is also affected and can greatly change the productivity. For these reasons, the effectiveness of Marangoni convection in refining should be quantitatively clarified and its control should be better understood."

Jan 1, 1997

By Young-Sool Jin, Heung Nam Han, Hong Joon Kim, Jae Kon Lee

A mathematical model was developed considering non-symmetric cooling' and stress distribution in both thickness and width direction of strip on a run-out table of hot strip mill. In order to solve a transient heat transfer equation including the heat evolved from phase transformation, a finite element method coupled with thermodynamic and kinetic analyses was applied. The heat capacity of each phase and heat evolution due to phase transformation were obtained from the thermodynamic analysis of the Fe-C-Mn-Si system based on a sub lattice model. The phase transformation kinetics of the steels was derived by using an inverse additivity technique with continuous cooling experiments. Heat transfer coefficients of strips on the run-out table were, by applying an inverse method, determined from the actual mill data under various cooling conditions. As for the stress analysis, the density change of strip due to cooling and phase transformation, and the transformation superplasticity were considered. A 90nstitutive equation for the transformation superplasticity, which is related to the phase transformation kinetics and the internal stress due to the density change of strip, was applied. A finite element method was adopted to calculate the deformation behaviour of strip on a run-out table of hot strip mill. Using the models, the temperature-phase-deformation history and distribution of a strip on the run-outtable was calculated.

Jan 1, 2001

By Toshiaki Tsuru, Takeshi Ohgai, Hisaaki Fukushima, Shigeo Kobayashi, Tetsuya Akiyama

"Electrodeposition behavior of Zn-Cr alloys from the methanol baths was investigated. In the methanol baths of low Cr3+ concentration, Cr (III) compound was incorporated in the deposits and no lusfrous Zn-Cr alloys was deposited. However, Cr was existed as metallic state in the deposits obtained from the baths of higher Cr3+ concentration. With an increase in water content in the baths, the chemical state of Cr in the deposits changed from metallic to trivalent state. Under the condition that metallic Cr can be electrodeposited, Zn deposition was significantly polarized to the potential of Cr deposition.INTRODUCTIONAn attention has been paid to Zn-Cr alloy plated steel sheet because of its excellent properties for body panels of automobile and electrical appliances [1]-[4]. This plating process can be operated using the sulfate solutions containing Cr3+ ion [1] - [6].In decorative single Cr plating, on the other hand, many attempts have been made to electroplate Cr from trivalent electrolytes, which is motived by environmental deficiencies of the presently used hexavalent process [7]. [8]. However, it has been reported that in the aqueous solutions the behavior of the electroreduction of 0 3+ is atypical due to the complicated nature of the chemistry and electrochemistry of cr3+ species [9]-[11]. Even in Zn-Cr alloy plating, it is difficult to codeposit metallic Cr with Zn in simple sulfate electrolytes [l]-[4], [12]. Therefore, it can be expected that the electrodeposition behaviors of Zn-Cr alloys as well as Cr are significantly changed when the electrodeposition is conducted in non-aqueous plating solutions.In this study, the electrodeposition of Zn-Cr alloy was conducted from methanol solutions to clarify the electroreduction mechanism of Cr3·-Cr0 in the alloy deposition process."

Jan 1, 2000

By Xin Zhang, Xu Zhang, Hao Bai, Ning Li

Organic Rankine Cycle (ORC) is an effective technology for low-grade waste heat power generation. In this paper, the thermal-dynamic performance of ORC system, in which low-temperature waste heat (from 40-140oC) is used as heat source, was evaluated with software RefProp8.0. The result indicates that in the range of low temperature, the working fluids like R601, R601a, R600a, R141b, R245fa and R245ca have better thermal performance. Furthermore, pilot-scale experiment using R245fa as working fluid was conducted, which validated the operation of the system for low-grade waste heat recovery. Finally, the economic feasibility of ORC has been analyzed for an ORC system using the waste heat from quenching water of blast furnace slag (80oC). According to the analysis, the project is reasonable in economy because the recovery period of investment is less than 4.2 years and environment-friendly since the CO2 emissions can be reduced by almost 43650.68t annually.

Jan 1, 2016

By G. B. Harris

Jaguar Nickel Inc. is developing the Sechol Nickel-Cobalt Laterite Project in Guatemala, Central America. Recognizing the potential advantages offered by chloride brine chemistry, Jaguar, at the facilities of Process Research ORTECH Inc, Mississauga, has developed an Atmospheric Chloride Leaching Process using a mixed chloride lixiviant to recover the nickel and cobalt, whilst leaving the majority of the iron and magnesium in the leach residue. Subsequent solution purification and mixed nickel/cobalt hydroxide product recovery is by standard precipitation methods, using recycled caustic magnesia, with a final stage of pyrohydrolysis of a portion of the concentrated magnesium chloride brine for recycling both the caustic magnesia and chloride lixiviant. The flowsheet that has been developed also offers opportunities for by-product recovery and efficient, environmentally clean process effluent management. The paper discusses some of the early leaching results in the context of strong chloride brine chemistry, with emphasis on how the controlling of water activity, hydrogen ion activity and chloride concentration permits the selective leaching of nickel and cobalt from an iron-magnesium matrix. Keywords: nickel, cobalt, iron, magnesium, Sechol, Guatemala, chloride, pyrohydrolysis

Jan 1, 2004

By G. L. Watt

Fine sized titanium diboride (TiB2) powders have been synthesized in a thermal plasma reactor. Precursor for the synthesis were rutile, boron oxide, and methane. The effect of plasma gas type, precursor ratio, and input power on the synthesis was studied. The produced powders were characterized by X-ray diffraction and chemical analysis. The purified powders were CIP'd, HIP'd, sintered and characterized for porosity, hardness, and microstructure and the results compared with a commercially available TiB2 powder sample.

Jan 1, 1995

By Sun Ying, Zhang Jing, Li Qiuju

A new process of enrichment Cu in molten copper slag under electric field is presented in this article. The experiments were carried out in the laboratory on a kilogram scale. The mobility of copper slag was improved by the technique of carbon reduction. The effects of temperature, electric field strength and intermittent feeding speed were investigated on Cu migration. The results showed that the best experimental conditions were the temperature at 1523K, electric field strength was 1.5V•cm-1 and feeding rates was 15 g•(10min)-1. The copper content of the slag decreased below 0.6wt%. The process was compared to the traditional electric furnace process of slag cleaning, there was reduced the energy consumption and heat loss, and also harmful gas emissions such as SO2 and CO2, accompanied by improved the efficiency of slag cleaning.

Jan 1, 2016

By Akira Yazawa

Experimental results for the distribution ratios of various elements between the slag, matte and/or copper in the silica-saturated copper smelting system were summarized. The experiments were carried out under an oxidative smelting condition with S02 gas flow, and also a reductive smelting condition equilibrating with metallic copper or iron. To evaluate the results thermodynamically, the availability of one atom cation base expression for the constituent compounds is emphasized from both of theoretical and practical standpoints. Both of oxidic and sulfidic dissolutions in slag are postulated for some elements such as copper, nickel and lead., and the experimental results are reasonably explained thermo-dynamically. The results for the mutual solubility between matte and ferrite slag and the distribution of minor elements between liquid copper and ferrite slag are also discussed.

Jan 1, 1983

By R. Hurman Eric

The electrode in a slag-resistance electric furnace is the central factor in the design and operation of the furnace by its role of conveying the smelting power, i.e. heat needed for the operation. The control parameters are the size and positioning in the slag bath which are defined by slag resistivity, furnace resistance, cell constant and power input sequence all of which are closely interrelated. The flow of heat generated by the electrode current determines the energy distributions and thus the furnace dimensions. Heat flow models concerning vertical, horizontal and combined two-dimensional flows are discussed. All these considerations are based on the experimentally determined slag properties such as its resistivity.

Jan 1, 1995

By M. Ide, K. Takemura, S. Taenaka, K. Shinzawa

"The laser characteristic is strongry dependent upon the stoichometry of forsterite (Mg2Si04) and YSO (Y2Si05) single crystals, because of change in the valency and occupied sites of doped Cr in the lattice so that mole ratios of Mg0/Si02 and Y203/Si02 in the above single crystals must be precisely analyzed. In this study ICP-AES was applied for analyzing the mole ratios. Emission intensities corresponding to Si and Mg or Si and Y were measured at the same time with internal standard method. Preparation of sample solutions, measurement conditions of ICP-AES and interferences by coexisting components were discussed, resulting in excellently precise detennination of stoichometry of the above single crystals.IntroductionIn conventional stoichiometric analysis of single crystals, the stoichiometry is detennined by analyzing each component separately with titrimetry and gravimetry techniques. On the other hand, by stoichiometric analyses using ICP-AES, emission intensities corresponding to components are measured at the same time with internal standard method. Consequently erros caused by variation of analytical condition are canceled out.Cr-doped Mg2Si04 and Y2Si05 syngle crystals are known as laser materials. The change of valency and occupied sites of doped Cr affect the characteristic of single crystal as aleser materials. The change of state of doped Cr.Stoichometric composition of Mg2Si04 is constructed by 2mole of MgO and 1mole of Si02, and Y2Si05 is constructed by 1mole of Y203 and 1mole of Si02. In this study, required analytical precision in component mole ratio is within an error of 0.0010 for Mg2Si04 (CV=0.05wt%), and within an error of 0.0030 for Y2Si05 (CV=0.05wt%) (Table I )."

Jan 1, 1998