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By Munyaradzi Kwatara, Ron Schonewille, Edgar Peek, Juzer Tayabally

"The potential recovery of nickel from a South-American saprolitic laterite ore using the segregation roasting technique was investigated. The ore was heated to temperatures that ranged between 900 and 1 000°C in a rotary kiln. In all the tests, the laterite ore was first mixed with a predetermined amount of calcium chloride and either coal or coke. By varying the temperature, calcium chloride and reductant in the different tests, a preliminary set of optimal conditions was established for the specific laterite ore that was tested. A combination of chemical analysis and electron-probe-micro-analysis (EPMA) were used to determine and evaluate the effectiveness of segregation roasting on the recovery of nickel. The present paper describes the test procedure and the results that were obtained.IntroductionIt is known that laterite ore resources account for an estimated 72% of the world's nickel resources, with sulfide sources accounting for the remaining 28%. Yet sulfide resources account for 58% of the world's primary nickel production while laterite resources account for the remaining 42% [I]. There are numerous reasons for this discrepancy, but the most important one is the mineralogical and compositional complexity that is associated with laterite ore deposits. For example, this complexity currently offers only limited opportunities for upgrading, thereby creating capital intensive whole ore processing facilities. It then follows logically that the identification and application of a low-cost processing option for the treatment of laterites could potentially open up an opportunity for exploiting these vast untapped laterite resources.To this end, a preliminary screening investigation was initiated by Xstrata Process Support to evaluate the potential application of the so-called (nickel) segregation process as a unit operation that could potentially be integrated into a laterite processing flow sheet. Laboratory bench tests were performed on this segregation process and this paper details some of the findings from this preliminary investigation."

Jan 1, 2011

By Laurentiu Nastac, Ruslan Mudryy

"This paper investigates the solidification of cast energetic materials. An active cooling and heating (ACH) technology and a mechanical vibration (MV) technology were applied to achieve unidirectional solidification during casting and to reduce cracks, gas pores, and shrinkage defects. The design parameters of these technologies were developed via Computational Fluid Dynamics (CFD) modeling and thermal stress analysis. Concerning the ACH technology, the number of cooling/heating sections and their temperature profiles and time sequences were optimized based on the thermo-physical properties of the energetic material as well as the riser and mold diameter, thickness and type. The ACH technology will also decrease the thermal stresses during casting of energetic materials and therefore minimize the formation of potential cracks that may form during the casting process. The MV technology will help to remove air entrapped during pouring process and decrease the detrimental gap size between the projectile and the solidified energetic material.IntroductionCasting processes are widely employed in the manufacture of products with intricate shapes and, in particular, in applications where the material of the final product is sensitive to machining. It is especially useful in processing of energetic materials. The cooling conditions applied in the casting process can affect the quality of the final cast in terms of void formation, residual stress distributions, and mold separation. Substantial shrinkage is also observed due to the density change upon solidification [1-3]. Residual stresses are known to be closely related to the formation of cold cracks and hot tears during casting. The formation of a gap between the mold and the cast material is of critical importance due to its deleterious effect on heat removal and on crack formation. In the casting of energetic materials all these defects can significantly impair the detonation velocity, Gurney energy, and insensitive munitions characteristics of the formulation, and lead to catastrophic accidents in explosives handling [ 4-5]. Imposition of carefully controlled cooling condition is thus critical in optimizing the cast quality that could help avoid such destructive effects."

Jan 1, 2013

By S. S. Ryu, J. C. Kim, H. Lee, Y. D. Kim, I. H. Moon

"Recently, W-Cu alloy becomes one of the very important candidate materials for heat sink and packaging in the field of microelectronics due to its good thermal properties. The metal injection molding of W-Cu powder can satisfy the requirement for mass production of complex shaped parts in microelectronic devices. In the present study, the application of MIM process to the nanostructured W-Cu powder prepared by mechanical alloying was investigated. The multi-component binder system of 45PW+ l 5BW+ 30PE+ I OSA was proven to be suitable one for the MIM of the W-Cu composite powders by adopting the debinding cycles of multi-stage in N2 and H2 atmospheres. Other process conditions for the MIM of the nanostructured W-Cu composite powder were also studied. The MIM debinding part of W-30wt.%Cu was sintered to the relative density of more than 96% by sintering at 1200 °C for !hour in H2 atmosphere. Such an improvement of sinterability was attributed to the intrinsic homogenous and fine mixing state of W-Cu phases in nanostructured W-Cu composite powders, and also partly to the effect of the activated sintering by the presence of impurity introduced during the extensive milling.IntroductionW-Cu alloys have been widely used for heavy duty electrical contacts and arcing resistance electrode(1-2). Recently there has been a growing interest in this W-Cu alloy because of its superior thermal managing properties and its high micro wave absorption capacity(3). Such W-Cu alloy parts are conventionally fabricated either by the Cu infiltration sintering technique or by hot pressing of W-Cu powder mixtures. However, these conventional PM techniques are hardly applicable for mass production of small size parts with a complicated shape such as the parts required for microelectronic devices. The metal injection molding(MIM) technique is potentially applicable for the mass production of small and complicatedly shaped parts compared with other PIM forming techniques."

Jan 1, 1998

By Fabiola Alvarez, Ana E. Bote, Daniel Pasquevich

"The oxidation of aluminum and its alloys was extensively studied for improving the corrosion resistance in structural materials having high specific strengths. But this reaction involves the formation of a very thin barrier layer on the metallic pieces. Furthermore, the ·recent development of the directed melt oxidation process for producing metal-ceramic; composites has renewed the interest in the study of interaction between gases and metals. Oxidation experiments in the presence of different chlorine partial pressures and at different temperatures were performed in ·a thermogravimetric balance, and microstructures were analyzed by electronic microscopy and X-ray diffraction. The oxy-chlorination kinetics was determined and the oxide formed W(IS amorphous at temperatures below 600 °C and crystalline .at higher temperatures. The appropriate experimental conditions for the fastest completed oxidation was further determined.IntroductionThe use of fine powders for the manufacture of ceramic components has significant advantages. They include excellent sinterability; low sintering temperature and better microstructure leading to improved mechanical properties. The conventional method of producing fine oxide powders involves controlled precipitation and pirolysis of suitable salts. The main limitation of the high temperature decomposition route is the evolution of environmentally unacceptable and corrosive gases. Controlled precipitation of hydroxides from solutions of salts, followed by thermal treatment involves large volumes of solutions and the calcination step that can induce grain growth (1).Direct oxidation of aluminum metal for producing alumina powder requires high temperatures for the direct oxidation of molten Al alloys by a vapor phase oxidant process (2, 3) or high technological process like thermal plasma reactor ( 4).Oxidation of high purity aluminum (5, 6) below the melting temperature· is initially characterized by a nearly linear reaction rate, followed by a rate which decreases rapidly with further weight gain. However, the oxidation rate of an aluminummagnesium alloy is much faster and it does not conform to any common oxidation law, but it is nearly parabolic at temperatures between 200 and 400 °C, an nearly linear· above 400 °C."

Jan 1, 2000

By H. Sieber

Multilayer samples of tantalum and aluminum with the composition of Al-25Ta were prepared by cold rolling of elemental foils. The microstructure and phases were characterized by XRD, SEM and TEMISAED and the reactive phase formation was examined by DSC and DTA measurements in multilayer foils rolled for different deformation levels. The rolling procedure yields a decrease of the Ta particle size in the Al matrix and also results in the formation of a multilayer structure with a thickness of the elemental foils down to 200 nm in average. No phase formation is observed during the cold rolling procedure. While XRD and DSC measurements show no phase formation up to the melting of aluminum for samples rolled up to 40 F&R (fold and rolling) passes, in samples rolled for 50 or more F&R passes a first phase formation reaction yield an interfacial layer of TaAl3. Contrary to former studies in the investigated cold rolled Al- 25Ta multilayers the reaction starts at temperatures as low as about 340°C. The first stages of the reaction are associated with two exothermic maxima, that increase in amplitude and shift to lower temperatures with increasing number of F&R passes. At higher temperature the TaA13 reaction layer thickens very sluggishly and yields a third exothermic maxima at about 600°C. Isothermal DSC scans show the reaction is not finished for samples containing elemental particles larger than 1 pm after annealing at 550°C for 5h. In all the investigated samples no Al- Ta phase other than Tad3 was observed to grow for heat treatments up to 800°C. Multilayer samples heated up to 1400°C show a morphology consisting of small AITa2 particles embedded in a single phase TaA13 matrix. The multilayer microstructure and reaction product morphology are characterized by SEM and TEM investigations in cross-section and plan view geometry.

Jan 1, 1998

By Helvio P. G. Santafé Jr., Ruben J. S. Rodriguez, Sergio N. Monteiro, Teresa E. Castillo

"The coir fiber extracted from the husk of the coconut fruits are worldwide available in tropical regions as a low cost lignocellulosic by-product for many applications including composite filler in automobile parts. Possible uses above room temperature require information on the thermal behavior of these coir fiber composites. Therefore, the objective of this work was to perform thermogravimetric, TGA and DTG, analysis on polyester matrix composites incorporated with different volume fractions of coir fiber. In general, it was found that thermal degradation associated with weight loss occurred in three stages. Changes were also observed in the DTG peaks that could be attributed to the coir fiber participation through the decomposition of its lignocellulosic structure.IntroductionThe development of new materials has always been motivated by the need of improved properties. This was the case of modem composites with combination of properties that surpass those of conventional monolithic metallic alloys, ceramic or polymers, from which composites are made. A typical example is the synthetic fiber reinforced composite with specific strength i. e, ultimate stress divided by density, higher than any other monolithic material. Today, however, our global society is concerned with serious environmental problems and thus demanding that new materials be developed with distinct characteristics. They are known as environmentally correct and are expected to be sustainable, which corresponds to the condition of being biodegradable, renewable, recyclable and neutral with respect to C02 emission, considered the main responsible for global warning [1]. Synthetic fiber composites cannot meet these requirements. Consequently, new composite reinforced with cellulose-based natural fiber are being developed [2-8] and are already replacing the synthetic ones in several engineering fields including the automobile industry [9-11]. These composites have additional advantages owing to the lignocellulosic fiber benefits of being diversified, abundant, less expensive, lighter and of societal interest [8]. In some cases even technical advantages such as non-abrasive effect to processing equipments and more flexibility exist in comparison to synthetic fibers."

Jan 1, 2011

By Kerri-Ann Hue, Kerry Hasapidis, Ken Babcock, Patrick O'Hagan

"Metallic nanoparticles exhibit properties that are significantly different from individual atoms or bulk materials. Their applications are diverse and have varying uses in areas such as cancer treatment, biochemical sensors, nanoelectronics, and drug delivery. For each application extensive characterization must be performed in order to probe the unique properties of these nanoparticles. In this study, ultra-high resolution mass sensors consisting of MEMs-fabricated, suspended microchannel resonators (SMRs) were used to determine the size and concentration of metallic nanoparticles. With femtogram (10- 15 g) mass resolution, ultra-high resolution mass sensors can weigh individual particles suspended in fluid, and so measure their mass, density, and size. Particle size analysis with these sensors provides excellent accuracy and resolution compared to mature technologies such as light scattering. This technique also provides quantitative information via the ability count particles.IntroductionThe unique electronic, chemical, and optical properties associated with nanoparticles vary with their size, shape, and composition[ 1-4]. These properties are attributed to increased surface area and nanosized mean free path of electrons to the particle surface. Nanoparticle colloidal solutions have been prepared and are commercially available. In recent years, noble metals such as gold, copper, and silver have been extensively researched[5-7]. In order to tailor the optical, electronic, and electrical properties of nanoparticles, size and shape must be controlled. For many applications a monodisperse colloidal solution is ideal. Methods of size characterization include Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), and Electrophoretic Mobility Measurements to name a few[6, 8]. Although TEM can provide shape and size distributions, sample preparation requires that samples be dried on a metal grid and cannot be analyzed in solution. DLS uses curve fitting algorithms that while useful for determining mean particle diameters are not ideal for polydisperse colloidal solutions. New technologies are therefore needed to accurately determine the particle size distributions of metallic nanoparticles."

Jan 1, 2011

By Lijun Liu, Yingwei Li, Jianhua Liu, Jinhui Peng

"As essential equipment in the metallurgical industry, current air heat exchangers cannot meet the requirements of high temperature heat transfer. In this paper, an energy efficient air heat exchanger, based on accumulation of the heat generated by microwave absorbing materials, is presented according to heat transfer theory and principles of the microwave field. A tubular shaped heat exchanger was designed and built up through temperature-rising curve, and experimental research of microwave high-temperature air heat exchangers was carried out. It was found from experiments that the tubular shaped heat exchanger fabricated using material B could be used for high temperature heat transfer system, and equilibrium temperatures could reach up to 457—485?.IntroductionHeating or cooling of air by heat exchangers is commonly practiced in a wide range of industries including construction, chemical, machinery, textile, printing, and dyeing [1-3]. Generally such heating or cooling of air is achieved in pipe heat exchangers. There are several drawbacks for such heat exchangers, namely, (i) the limitation of temperature to which the pipes can be heated, (ii) tendency to oxidize at high temperature, and (iii) poor strength of metallic pipes at high temperature. These limitations do not allow pipe heat exchangers to be operated at high temperatures [4-6].Microwave heating of inert solids, which are stable at high temperature, is a possible solution to achieve high temperature of the medium in air heat exchangers. It is well-known that microwave heating is an efficient, clean, safe, easy-to-control heating method. Microwave heating utilizes the dielectric and magnetic properties of a material. When microwaves penetrate and spread into the dielectric material, electrons, ions, etc move in the internal electromagnetic field, while the elasticity of inertia and friction impede these movements. This results in a significant thermal effect, increasing the surface temperature rapidly [7-8]. This paper studies mainly design and experimental research of microwave high-temperature air heat exchanger."

Jan 1, 2011

By Leiv Kolbeinsen, Stian Seim, In-ho Jung

"The current work presents new experimental data in the iron-unsaturated region of the FeTiO3-Ti2O3-TiO2 slag system. The samples are prepared by melting pure reactants in a high frequency induction furnace that employs a cold crucible. A similar experimental set-up has been described in literature and proven suitable to investigate high titania slags. The FeO content of the samples range from 3.7 to 21.8 wt% and the Ti2O3 content range from 3.6 to 30.1 wt%. The liquidus temperatures of the samples are measured in-situ by a spectropyrometer and range from 1450 to 1645 °C.In addition, an improved thermodynamic database for the FeO-Ti2O3-TiO2 system has been developed. Ternary parameters have been included and optimized to fit previously published experimental data. This optimization minimizes the discrepancy between experimental data and thermodynamic calculations as previously discussed in literature. New liquidus projection plots are proposed for the FeO-Ti2O3-TiO2 and the FeTiO3-Ti2O3-TiO2 systems.IntroductionIlmenite (FeTiOs) smelting is a relatively small industry world-wide. However, a reasonable focus on the process has been applied in Norway due to the location of one such smelter in Tyssedal, which is located in the western part of Norway. The process is essentially carbothermal reduction, where most of the iron in the ilmenite is reduced to its metallic state, and the titanium oxide is concentrated in the slag product. The metallic iron is sold as a high purity pig iron and finds applications in cast products. The slag concentrate is further processed for the production of TiOvpigment and/or titanium metal. This further processing can be performed through different routes according to the purity of the slag concentrate."

Jan 1, 2012

By Lev Levin, Sergei Lesokhin

"The formation of titanium carbide during hot filament assisted carburizing of NiTi alloy was investigated. Phase content and morphology of the diffusion zone were examined by X-ray diffraction, X-ray microanalysis, SEM, and Auger electron spectroscopy. The growth of stable and adherent TiC film was observed. A non-planarity of interphase boundary was noticed. The applicability of the chemical diffusion approach to the analysis of the experimentally observed interface instability is discussed. A criterion, taking into account the influence of growth stresses on the stability of the flat interface, is developed by means of linear perturbation analysis.Introduction.Equiatomic intermetallic NiTi belongs to a class of materials exhibiting the shape-memory effect. The unusual property of this compound promotes its application in many fields, from aerospace technologies to medicine. The relatively high ductility ofNiTi also permits its use as a matrix material in metal-ceramic composites. The objective of this work was to investigate the possible incorporation of a ceramic material (titanium carbide) into NiTi by gas carburizing.Free energy calculations indicate the potential to obtain TiC by carburizing Ni-Ti binary phases. The main obstacle to such a process is the high affinity of titanium to oxygen. At moderate temperatures the formation of TiC is preferable to titanium oxidation only if the partial pressure of oxygen is extremely low [1]. This problem was overcome in this work by the use of hot filament assisted gas carburizing. Due to chemical reactions occurring near the hot filament, the gas mixture, initially consisting of methane and molecular hydrogen, was enriched by atomic hydrogen [2], drastically decreasing the content of free oxygen in the carburizing atmosphere.The second part of this article concerns the theoretical analysis of reasons that lead to the development of the experimentally observed morphology of the diffusion zone. In particular, the influence of the growth stresses on the morphology of an interphase boundary is investigated."

Jan 1, 1996

By Qingyu Deng, Shiwei Ma, Wang Hua, Guibao Qiu

"The flow properties of the blast furnace slag bearing high TiO2 at high temperature like the viscocity may change a lot due to the formation of the carbonitride inside, causing serious problems on the separation between the metal and the slag. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process with iron ore bearing titania. In this study, the formation of Ti(C,N) in blast furnace and the influences of various factors on the Ti(C,N) formation are investigated by FactSage. It is found that the mass of Ti(C,N) would reach the maximum at 1480 oC, and the product is mainly TiN below 1620 oC, while it is mainly TiC above 1620oC. The order of the factors by the importance from strong to weak was: temperature, the content of TiO2 in slag, basicity of slag, the content of MgO and Al2O3.IntroductionThe titanium dioxide (TiO2) in iron ore bearing titania will be partly reduced by carbon to titanium carbonitride (Ti(C,N)) in blast furnace, causing serious problems on the separation between the metal and the slag because of the change of flow property. Therefore, the critical condition of the formation of Ti(C,N) in blast furnace is vital importance for the ironmaking process, especially for the smelting of iron ore bearing titania. Extensive experimental data in regard to the formation of Ti(C,N) has been reported in numerous papers[1-6]. However, only some discrete data can be obtained by experiment, and it is difficult to detect the mass of Ti(C,N) in slag. In addition, the experiment is difficult to be proceeded when the temperature is above 1600oC. Therefore, it is very difficult to make clear the critical condition of the formation of Ti(C,N) by experiment."

Jan 1, 2012

By Lijuan Li, Zheng Lu, Xin Xia, Qijie Zhai, Qingchun Li

"Pulsed current and pulsed magnetic field have been applied to the bainite transformation of Cr5 steel. Three groups of experiments were conducted. In the first group, ordinary resistance furnace was used for heat treatment. The Cr5 specimens were rapidly heated up to austenitization temperature 940 °C, held for 20 min, air cooled to bainite transformation temperature 350 °C, held for 10, 20, or 40 min and then air cooled to room temperature. The second and the third group shared the same temperature-time curve with that of the first group, but their heat resources came from the Joule heat produced by pulsed current. 1.5 T pulsed magnetic field was exerted on the third group specimens when they were held at 350 °C, but the second group specimens did not undergo the treatment of magnetic field. It was found that both pulsed current and pulsed magnetic field obviously retarded the bainite transformation. The phenomena were discussed in terms ofliterature results.IntroductionApplying pulsed current and pulsed magnetic field technology are very pronnsmg ways to change the microstructure of materials by affecting the phase transformation process. People had found that pulsed current dramatically influences the behaviors of materials, for example, electromigration effect [l], the solidification of metals and alloys [2, 3], electroplasticity [4, 5], crystallization of amorphous alloys [6], healing of metal materials [7] and so on. As to pulsed magnetic field technology, a lot of effort had been spent on grain refinement in solidification of metals [8, 9], recrystallization of cold-worked metals and alloys [10] and Fe-based alloys solid-state phase transformation [11, 12]. Though application of pulsed current and pulsed magnetic field technology have proliferated in recent years, investigation on their effects on solid/solid phase transformation, especially bainite transformation, is lacking. The aim of this paper is to show the effects of pulsed current treatment (C-T) and the combined treatment of pulsed current and pulsed magnetic field (CM-T) on bainite transformation of commercial Cr5 steel"

Jan 1, 2014

By B. Ozturk, K. Ito, R. J. Fruehan

"A simulation model for bath smelting processes for the production of iron was developed which predicts the coal, flux, ore, and oxygen consumptions and the off gas volume, temperature and composition. The model is comprehensive in that it takes into account all of the important variables including coal composition, metal composition, ore composition, slag basicity, post combustion ratio, (PCR), prereduction degree (PRO), heat transfer coefficient (HTC) , flux, scrap charge, and heat losses. Four basic cases were considered: I. 30% PRO-50% PCR; II. 90% PRO-O% PCR; III. 60% PRO-30% PCR; and IV. 0% PRO-50% PCR. Several different coals were considered and a sensitivity analysis of the critical variables was performed. The model also estimates the sulfur content of the metal. The major conclusions included:1. Post combustion significantly reduces coal consumption but above 20% PCR little reduction of FeO to Fe can be performed with the off gas.2. Prereducing to FeO (Case I) and having as much post combustion as consistent with good heat transfer is an attractive process. This process only requires a simple pre reducer, uses less coal, and is relatively insensitive to the type of coal used.3. High off gas temperatures may pose a potential problem. The off gas temperature can be reduced by using an 02-Air mixture for post combustion, limiting post combustion or adding water to the gas.4. The use of CaC03 in place of CaO or of supplemental electricity does not appear attractive.5. The melting unit is theoretically an energy efficient scrap melter. For Case I using 200 kg of scrap as part of the charge the coal consumption decreases by about 80 kg.6. With PCR > 30% the FeO content of the slag is expected to be 2-5%, and the metal will not be saturated with carbon. These factors and the increased sulfur load since coal is the fuel indicate the sulfur content of the metal may exceed 0.25%"

Jan 1, 1988

By Yongyong Gong, Qijie Zhai, Zhichen Zhang, Qixin Li, Zhishuai Xu

"Microstructure of semisolid slurry of Al-4.5wt.%Cu alloy was investigated with pulse magnetooscillation (PMO) treatment, the results showed that the PMO treatment can refine the crystal structures of Al-4.5wt.%Cu alloy significantly. The discharging frequency of PMO had a great effect on the solidified structure transformation of semisolid slurry of Al-4.5wt. %Cu alloy, and the primary a-Al particles become much finer and rounder with an increase of discharging frequency. However, over a certain discharging frequency, the grains of primary a-Al become coarse.IntroductionOver the last decade, a lot of attentions have been paid on metal rheoforming process [1-4], since it has higher mechanical properties of formed components, strength to weight ratio and age hardenablity. Nevertheless, semi-solid forming is always performed at high solid fractions (40%-60%), so it has the limitation of viscosity, a tends to be difficult to pour semisolid slurry into the hole of the shot sleeve. Therefore, a series of novel semi-solid slurry preparation methods and rheoforming techniques have been invented, such as, semisolid vibration treatment [5], rheocasting [6], pulsed magnetic field process [7], annulus electromagnetic stirring [8], via ultrasonic vibration process [9], equal channel angular extrusion (ECAE) process [l0] and straininduced melt activation (SIMA) process [11].The electromagnetic field is characterized by its effective grain refinement, green, convenient manipulation and without contamination of melt. The mechanisms of dendrite was fragmentation by electromagnetic field have also been largely proposed [12-14]. The broken dendrite arms then undergo a coarsening process to provide the globular structures and obtain much finer and rounder a-Al particles. When compared with other external electromagnetic techniques, Pulse Magneto-Oscillation (PMO) has obtained more fuvors, owing to narrower pulse width and much lower energy consumption. Furthermore, the PMO treatment can reach finer grains with shorter time treatment [16, 17]. This work aims to study the effects of different discharging frequency ofPMO treatment on the microstructure transition of the semisolid slurry of Al-4.5 wt.%Cu alloy."

Jan 1, 2014

By Rudolf Keller

"EMEC Consultants is developing a process to extract oxygen, aluminum and silicon from lunar anorthositic soil. The process will provide oxygen in space for propulsion, aluminum as a structural material, and possibly silicon for the construction of solar cells.The evolution of the process concept in the course of our present NASA-sponsored SBIR effort is discussed. A molten salt electrolysis producing aluminum and oxygen is the central step; inert anode technology is to be employed. Silicon will be produced by reducing the anorthite, CaAI2Si20S' with aluminum. In a steady-state operation, all components of the ore added have to be removed from the process, and the removal of calcium is a major topic of our experimental studies.Utilization of Lunar ResourcesUtilization of lunar resources may play an essential role in the exploration of the solar system and the conquest of space. High costs are involved in overcoming Earth's gravity to supply missions in space. Even at a low projected cost of $ 300 for transporting a pound of payload into Earth orbit -- today's costs are many times higher -- it appears attractive to use resources in space to produce needed materials. Processing of lunar resources on the lunar surface is an obvious possibility.Oxygen is a product of major interest. It is required for support of human life in space. Even greater quantities may be needed for propulsion, to conduct further missions into space. To satisfy this demand for oxygen through lunar processing requires a quite different solution than to supply oxygen on Earth, where oxygen gas is abundant and easy to extract from air or water. On the lunar surface, solid oxide materials have to be used. Hydrogen reduction of ilmenite and subsequent electrolysis of the resulting water is being studied [1]. Other suggestions include fluorination of lunar soil [2], reduction with lithium and electrolytic decomposition of the resulting lithium oxide [3], and aqueous HF leaching [4]."

Jan 1, 1988

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Kellie Provazi

"The purpose of this paper is to study metal separation and recovery from a sample composed of a mixture of the spent household batteries main types, using liquid-liquid extraction and metals electroplating. The electrolytes preparation consisted: grinding the waste of mixed batteries, reduction and volatile metals elimination using electric furnace and acid leaching. From this solution were studied the liquid-liquid extraction using Cyanex 272 [bis(2,4,4-trimethylpentyl) phosphoric acid] with tributyl phosphate as extracting agent. After study of solvent extraction and stripping has been recover and separate the metallic ions and with electroplating was recovered the manganese, copper, nickel and cobalt in their metallic forms.IntroductionCurrently has increased the consumption of electronics devices such as mobile phones, laptops, wireless phones, comcorders, etc., especially portable devices that use batteries as a power source, and consequently has increased the disposal of such material.Increased consumption of this devices is caused by several factors including increased popularity of consumer electronics devices, has become essential of modem life. Therefore, recycling of batteries is important because its reduces the waste of raw materias and nonrenewable resouces used in manufacturing these materias and help prevent potential environmental risks associated with improper disposal of these products together with household garbage.The batteries have a very diverse composition, containing metals such as zinc, lithium, nickel, lead, mercury, cobalt, cadmium, iron, copper, manganese and rare earths. Some components may contain hazardous materials such as cadmium, mercury and lead, and can contain acids or bases.This research line is a pioneer in dealing with a single process for recycling a mixture with all batteries types, for only processes that exist in the world are based on the recycling a mixture with all types of batteries, for only processes that exist in the world are based on the recycling of one or two types of batteries [1-4]. This process necessitates the previous separation of the batteries by type."

Jan 1, 2012

By J. D. Sunderkötter, M. F. Stroosnijder, V. A. C. Haanappel

"TiAI-based intermetallic compounds have attracted considerable interest as structural materials for high-temperature applications due to their low density and substantial mechanical strength at high temperatures. However, one major drawback hindering industrial application arises from the insufficient oxidation resistance at temperatures beyond 700 °C. In the present contribution some general aspects of high temperature oxidation of TiAI-based intermetallics will be presented. This will be followed by a discussion of the influence of alloying elements, in particular niobium, and of the effect of nitrogen in the oxidizing environment on the high temperature oxidation behaviour of such materials.Extended AbstractIntroductionTiAI-based intermetallics are being considered as construction materials for high temperature components, e.g. in aircraft and car engines, due to their low density and substantial mechanical strength at high temperatures, see e.g. [1,2]. The best ductility can be attained with alloys consisting of y-TiAI with around 5-15 vol.% Q2-Ti3AI. However, one major hindrance to industrial application arises from the insufficient oxidation resistance at temperatures beyond 700 aG. In spite of their high aluminium content, TiAI-based intermetallics do not generally form long-lasting protective alumina scales. After longer exposure times the scales, which are initially rich in alumina, deteriorate and scales consisting of mixed alumina and titania predominate, with high growth rates similar to pure titania.It is not the intention of the present paper to present a general overview of the high temperature oxidation behaviour of TiAI based intermetallics, for which the reader is referred to the literature [3,4]. In the present contribution some general aspects of high temperature oxidation of TiAI-based intermetallics will be presented. This will be followed by a discussion of the influence of alloying elements, in particular niobium. The effect of nitrogen in the oxidizing environment on the high temperature oxidation behaviour of these intermetallics will also be considered."

Jan 1, 1996

By ChuanJie Cai, Zemin Zhuang, Jing Chen, Xuebin Hao, Shaobo Zheng

"Carbon which was used as heating and reducing agent in traditional iron and steel making process at present brought us large amounts of greenhouse gas harmful gases and dust seriously leading to the fog and haze condition. As one of ideal global new energies, Hydrogen has good features such as rich resource, high heat efficiency, cleanness, renewable and transportation. With the commercialization of hydrogen energy, the world energy structure will be changed greatly. Although many scholars have done a lot of researches and long-term exploration on hydrogen metallurgy, researches on the formation of metal iron phase in the process of hydrogen reduction of iron oxides in slag was rarely reported, which had important theoretical significance on the development of hydrogen smelting reduction process. Based on the thermodynamics and kinetics calculation, A laboratory experiment has been designed to research the iron phase formation during hydrogen reduction of iron oxides in the molten slag in this paper. SEM and EDS techniques were also used to observe and analyze the iron morphology. According to detection results, the influence of temperature, reaction time and surface tension on the morphology of the iron phase reduced were showed.IntroductionWith the increasingly severe global warming greenhouse effect, governments are paying more attention to no-carbon and low-carbon energy development and utilization. Hydrogen has received widespread attention around the world, which has rich resources, high thermal efficiency, large energy density, use clean, transportation, storage, renewable etc [1].The development of the hydrogen economy is new competition areas of the world economy for the 21st century. China should assess the situation, and achieve the important strategy of peaceful development as the realization of new industrialization, by establishing a ""hydrogen economy"" industry revolution which replaces fossil energy. The current hydrogen metallurgy process includes hydrogen direct reduction, smelting reduction and direct steelmaking process. Hydrogen plasma hydrogen metallurgy is the use of hydrogen as a reducing agent to replace carbon reductant, to reduce carbon dioxide emissions, and to ensure the sustainable development of ironmaking industry."

Jan 1, 2014

By Xiangru Chen, Honggang Zhong, Qijie Zhai, Qingqing Sun

"A horizontal directional solidification equipment, with an in-situ pouring system, was employed to physically simulate the solidification behavior of continuous casting. In this paper, the 2304 duplex stainless steel (DSS 2304) was investigated using this equipment due to its microstructure produced by continuous casting process was usually not satisfied. The grain size combined with the position of columnar to equiaxed transition (CET) of DSS 2304 were observed and the results showed these microstructure characteristics were very close to those of the continuous casting slabs. In addition, the influences of pouring temperatures and cooling conditions on the CET behavior were investigated. The results revealed that the length of the columnar grains decreased with decreasing the pouring temperatures and flow rates of the cooling water. Besides, the content of austenite decreases with increasing the distance from the chilled sidewall.IntroductionDuplex Stainless Steels (DSSs) have been widely used in industry for their excellent mechanical strength and superior corrosion resistance in Cl- environments when compared with other stainless steels [1,2]. Their good performances are mostly on account of the duplex phase structure-ferrite (d) and austenite (?) and the high proportion of alloying elements. Although, DSSs have good ductility, but worse formability compared to the austenitics, and this is the key to restrict DSSs application [3]. This is due to the differences properties between the two phases. The hot workability of ferrite (d) is better than austenite (?) and exhibits a lower flow stress during hot rolling processing [4]. The early workers had revealed that coalescent force of phase interface, microstructure, difference of mechanical property between two phases and the precipitations are the main factors affecting the formability of DSSs [5,6]. Another important reason that affects the alloy’s mechanical properties is columnar to equiaxed transition (CET) [7]. It often occurs during continuous casting solidification process and induces inhomogeneous mechanical properties and the microstructure varies with different processing parameters, such as pouring temperatures, cooling conditions (water flow rates in the cooling zones) and casting speed [8]."

Jan 1, 2012

By Manfred K. Walther

"Tests were conducted on instrumented plates cast in the Abex Experimental Foundry to compare recorded solidification histories with results computed for corresponding models simulated with the C.A.S.T. program. The first plate was cast of low alloy steel and the second of carbon steel with a graphite chill at one end. Both were cast in molds of bonded silica sand. Temperature histories were recorded in the castings, molds and chill. Exceptionally good agreement was achieved between computed and experimental data. Other investigators will find the results useful as a benchmark against which they can compare the results of their own calculations.IntroductionSince the early 1970's our foundry engineers have used both two- and three-dimensional versions of the G.A.S.T. program to gain knowledge of the solidification process [1,2,3]. Study of the computed data gave insight as to how the rigging and risering of specific castings might be changed or adjusted to improve quality and yield. New schemes based on such analyses were then recommended for implementation on the foundry floor. The degree of success of the new practice was subsequently evaluated after the part had been poured, shaken out and examined. Similar conditions were noted in the sectioned castings whenever porosity and voids had been predicted by the computations. Appropriate modifications, when found successful in the model, were applied to the process. This led to a reduction, if not complete elimination, of the defects. Such results gave credence to the use of these programs as an aid in the production of better castings.Earlier investigations on simple shapes revealed excellent correlation between output derived with the G.A.S.T. program and exact solutions. Results also compared favorably with data calculated using other codes as reported in the literature [4] and summarized in the Appendix. However, since the computer program had not been verified by direct experiment, it was decided to run instrumented tests to check the theoretical predictions with actual measurements."

Jan 1, 1986