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By A. Ohno

"A new near net shape casting process, OHNO Continuous Casting (OCC), has been recently developed. In this process, molten metal is fed into a heated mold maintained at a temperature above the solidification temperature of the metal being cast. Solidification begins from the central core of the casting rather than the wall of the mold. With the heated mold, the formation of crystals on the mold wall is prevented and solidification occurs out of contact with the mold surface. This produces near net shaped products with smooth, mirror-like surfaces and unidirectional grain structures free from cavities, porosity and segregation. Any crystals formed at the beginning of solidification decrease in number as solidification progresses and eventually a single crystal product is obtained. This process is applicable to any metal alloys, converting them into new materials with superior properties and quality.IntroductionAs a result of growing technical demands for more advanced and diversified materials, the OHNO Continuous Casting (OCC) technology has found many new applications in industry. Considerable interest in the process has been shown in Japan and other countries because of its distinct ability to:produce a single crystal, (1)produce a remarkably clean cast surface without a witness mark,provide extremely good ductility,and reduce casting defects and segregation.This paper provides an overview of the principle of the OCC process and describes the remarkable characteristics of the material produced by this method."

Jan 1, 1988

By James E. McNulty

Today's energy era is the beginning of a transition from the Petroleum Age to a future age of renewable fuel resources. Fuels for the transition era will come from unconventional sources and conversion technology. Affecting the practicability of transition technologies are attitudes of the public, capital requirements and availability, patterns of fuels utilization, producibility of fuels and the actions of governments. Primary energy sources to replace deficiencies of oil and gas and provide growth in the period of transition will be coal, oil shale, nuclear energy and peat.

Jan 1, 1981

By V. B. Chernyavsky, Ladokhin S. V.

Equipment and continuous casting technology for the production of small diameter copper rods and tubes are described. Industrial copper wastes, such as scrap and shavings, were used as the charge. An electron-beam installation for rod and tube production includes a crucible with an electromagnetic stirring system and a pouring hole in its bottom, a bottomless mold, .and a special cooling system, which includes an oil and water cooling devices. For the first time in the electron-beam technology, rods of 8 mm and 14 mm diameter mm tubes of 14 mm external diameter and 7 mm internal diameter were produced through continuous casting by pulling them out of the vacuum chamder into the atmosphere with depressurizing the vacuum chamber. The production capacity of a single strand continuous casting machine was 200 mm/tnin for rod casting and 150 mm/min for tube casting.

Jan 1, 2000

By Carlos Carnurri

A characterization of mechanical properties of fire refined copper has been done in order to link ductility with oxygen content. The results show four different copper mechanical behaviours as temperature increases, where the oxygen con- tent, as Cu20 segregated, has a deleterious effect on ductility. It is concluded that until 500 ppm oxygen content, the fire refined copper could be rolled without remelting for deoxidation. Also a subsequent cold rolling could be done without intermediate annealing.

Jan 1, 1994

By K. Morsi, S. K. Kassegne, K. S. Moon, A. Numula

"Current Activated Tip-based Sintering (CATS) is a new process for the powder-based manufacturing of macro, micro and possibly nano-scale features and shapes. CATS enables the selective sintering of powders by localizing current activation conditions through an electrically conducting small tip (either in the stationary or moving mode). This paper presents preliminary experimental results on the CATS of reactive mixtures of Ni/Al powder to form nickel aluminide intermetallics. Preliminary investigations on the effect of current on the reaction characteristics are discussed.IntroductionSpark Plasma Sintering (SPS) has been the subject of intense research over the past decade [1,2, 3,4,5,6]. The process boasts remarkable advantages which include ultra fast heating rates (hence by-passing low temperature non-densifying sintering mechanisms), considerably lower sintering temperatures and shorter sintering times than achieved in conventional sintering. The process is however limited to the generation of simple geometries on the macro-scale. Recently three of the authors conducted work on a novel process ""Current-activated tip-based sintering (CATS)"" [7], where electric current is passed through a conducting tip that is placed or allowed to travel over a powder bed/compact to locally sinter powders. lD, 2D and 3D micro-scale sintered shapes can be generated with the possibility of 3D rapid prototyping on the macro/micro or nano-scale. Although CA TS of single phase powders has been conducted, the CATS of reactive powders has not yet been investigated.The Ni-Al phase diagram contains five intermetallic compounds, AhNi, AhNh, AlNi, AhNi5 and NhAl. Out of these intermetallics, NiAl and NhAl have received the vast majority of scientific and industrial interest [8]. NhAl can be formed by reaction synthesis, where nickel and aluminum reactant powders are heated to a reaction ignition temperature at which the reactant powders are converted to the intended intermetallic product. The reaction is exothermic which gives rise to considerable compact self heating, thus instantaneously raising the compact temperature by several hundred degrees which facilitates sintering [8]. Applying and electric current locally would not only provide for a rapid local reactive sintering, but would generate a number of intriguing scientific investigations. For example, of interest would be, how would the reaction propagation and microstructural/phase evolution be affected by the temporal and spatial temperature and current distributions."

Jan 1, 2011

By Donald R. Sadoway

The viability of treating certain forms of hazardous waste by direct electrolysis in molten oxides is under investigation. Secondary residue or waste mud produced in the course of chromate chemical production is the focus of attention in this study. The goal is to reduce the water soluble hexavalent chromium either to insoluble trivalent chromium or to chromium metal. Electrolysis tests have been conducted in a high temperature cell containing chromate sludge dissolved in an electrolyte composed of Al2O3, SiO2, CaO, and MgO. Oxygen production on a carbon-free anode has been confirmed.

Jan 1, 1992

By Richard D. Hagni

The mineralogy of dusts from the lead sinter and lead blast furnace at the Doe Run Smelter at Herculaneum, Missouri is being studied by reflected light microscopy and scanning electron microscope-energy dispersive spectroscopic analysis (SEM-EDS). Oust from the sinter plant consi5ts of abundant slag and galena particles, and lesser amounts of coke, sinter, and chalcopyrite particles. In contrast, dust from the blast furnace consist of abundant coke and sinter particles, and lesser amounts of slag, galena, chalcopyrite, metallic lead and lead-copper particles. The particles in dusts from remote sampling sites !-l mile from the sinter plant and blast furnace are fine-grained and composed principally of calcium-aluminum silicates that are locally derived, but some of the larger particles consist of sinter, slag, galena, and other minerals. Additional dust samples from the plant and remote sites are currently being studied.

Jan 1, 1991

By Gary K. Elliott

Many industrial processes generate hot waste gases which contain particulate pollutants. Conventional clean-up techniques suffer limitations either because collection efficiency is low or because the gas must be cooled before treatment. thereby increasing costs and preventing energy recovery. The application of increasingly stringent environmental legislation to the non- ferrous metallurgical industry Is presently illustrating these conventional technology limitations. Low density ceramic media allow filtration to take place at high temperatures and are now rapidly becoming accepted in many industries. This paper reviews experiences with a proprietary low density ceramic filter element, Cerafill. It includes consideration of the structure, composition. typical operating and case studies with particular reference to non-ferrous metallurgical furnace applications.

Jan 1, 1992

By Cheng Yan, Yugang Li, Qian Wang, Lizhi Zhang

In continuous casting process, mold powder has lots of metallurgical effects, such as covering the molten steel to prevent liquid steel from oxidation by air, preserving heat for top layer liquid steel, lubricating initial shell and so on. However, mold powder also can deteriorate the quality of final products obviously after the entrapment of mold powder in steel. In the present work, based on the similarity theory the effect of technological parameters on mold powder entrainment was investigated by water model. Experiment was carried out in the water mold using oil and water to simulate slag and steel, respectively. The results showed that increasing casting speed increased the water-oil interfacial fluctuation and entrainment frequency; viscosity of oil also had a great impact on the interface fluctuation and entrainment; water-oil interfacial tension effect the entrainment while not changing the interfacial fluctuation; submergence depth had little impact on entrainment and interfacial fluctuation.

Jan 1, 2015

By Dongping Duan, Hongliang Han, Li Zhong, Siming Chen, E Zhou

In this study, physical, chemical and microscopic characteristics of Celestine were investigated firstly. Based on which, the thermodynamic analysis of Celestine reduction was discussed. And the experiments of Celestine carbon-containing pellets used in rotary hearth furnace process were studied. The results showed that it is feasible to deal with Celestine by rotary hearth furnace direct reduction process. When the temperature is 1200°C, C/O ratio is 0.8 and holding times is 20min, the conversion rate of SrSO4 in Celestine is above 95%, the utilization rate of Celestine is nearly 100%. This study can provide theoretical and technical basis on economical and rational use of Celestine.

Jan 1, 2016

By D. J. Donaldson

The PAL process for recovering nickel from laterite ore requires large volumes of thick abrasive slurry to be raised lo high temperature (245°C+) and pressure (40 atm.+). Flow diagrams of the process typically result in facilities that have serious operating and reliability problems. Most of the problems can be attributed to using multiple pump stations to raise the slurry to autoclave pressure, large amounts of flash and live injection steam to heat the slurry to autoclave temperature and several steps of flash cooling to lower the temperature and pressure of the abrasive autoclave slurry down to atmospheric conditions. It is proposed that operating and reliability problems of PAL facilities can be mitigated by using Tube-in-tube heat exchangers and "float type" positive displacement pumps. The subject paper describes an innovative application of such equipment in the facility design of the PAL process. Keywords: Nickel, Laterite, PAL, Heating, Slurry

Jan 1, 2004

By I. E. A. Aghachi

During static strain-aging of low carbon steel, when the material is pre-strained, the dislocation density increases. If totally or partially unloaded and aged for a prescribed time, interstitial solute atoms diffuse under the influence of the dislocation stress fields, thus tending to lock dislocations causing an increase in yield stress. If held for long periods at certain aging temperature, a decrease in yield stress (over-aging) is observed following the initial increase. This behaviour has been variously attributed to either recovery of cold worked dislocation structure and/or formation and coarsening of carbide precipitates. The present work demonstrates that, using a "process control" model for the competing processes of hardening and softening, dislocation recovery is responsible for over-aging of mild steel specimens under conditions tested during this investigation. Keywords: Strain-aging, Precipitation, Recovery

Jan 1, 2003

By Fan Xiao-Hui, Jiang Li-Juan, Chen Xu-Ling

"In order to solve air leakage of sintering testing cumbersome, inaccurate results, and other issues, the sinter machine air leakage characteristics were studied, and combining the mathematical modeling and the field detection. The temperature before air leakage was calculated by mathematical model, energy balance equation was established according to sintering process, using Adams prediction correction method which has stronge stability and high precision, to solve hyperbolic partial differential equation with astringency problem. The temperature after air leakage is detected by instruments, according to energy conservation calculation the sintering air leakage rate. According to the sintering continuity and periodicity, sintering air leakage location diagnosis expert system was established to judge specific air leakage locations.IntroductionStrengthening of modern blast furnace production depends on the quality of the raw material preparation to a large extent [1]. Technical and economic index of modern blast furnace production is advanced; the most important reason is the use of concentrated feed. Sintering plant is the ""kitchen"" of blast furnace’s concentrate. As we all know, sintering plant is major energy consumption of steel plant, in sinter process energy consumption, the solid fuel consumption of total energy consumption is 75%~80%, power is 13%~20%, ignition and combustion is 5%~10%. To reduce the air leakage of sintering plant is an effective measurement to save energy consumption. At present, our air leakage of sintering compared to the other developed countries is still a long way to go. Japan’s air leakage rate is about 30%, and 35%~60% air leakage of sintering machine at home, a big gap exists between the plants. At present the determination of air leakage is all for manual operation, long measuring period, considerable manpower and resources, and the results are significantly affected by operation. For air leakage of sintering control lag issues, research and development of diagnosis expert system for on-line monitoring model for air leakage and, through this research can reduce the use of detection equipment, detect sintering air leakage, improve the yield and quality of sintering production, reduce energy consumption, and extend equipment life span."

Jan 1, 2012

By J. B. Vander Sande, I. G. Solórzano, B. S. You, P. M. Jardim, W. W. Park

"Alloys with six different compositions in the system Mg-Ca-Zn were produced by melt spinning. The aging behavior of alloys was investigated by measuring the changes in microhardness after isochronal aging and the microstructure was analyzed by means of transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDS), scanning transmission electron microscopy (STEM) and scanning electron microscopy (SEM). All six compositions in the as-solidified condition show a difference in microstructure between the wheel contact side (zone A) and the free surface side (zone B) as a result of the differences in the solidification rate across the ribbons. One of the alloys (Mg-l.5wt%Ca-6wt%Zn) was chosen to be more deeply investigated in this work as it exhibited grain boundary films and an age hardening behavior was produced in that alloy.IntroductionMagnesium is the lightest of all the commonly used metals, and very attractive for applications in transportation. It also has a number of other desirable features, including good ductility, better damping characteristics than aluminum, and excellent castability. However, there are some negative features, such as high reactivity in the molten state, inferior fatigue and creep resistance as compared to aluminum, poor corrosion resistance and high production cost.In recent years there has been a significant increase in magnesium use as a structural material. These structural applications include aerospace, automotive and nuclear industries as well as appliances and sporting goods (1 ). According to reports on Mg-Zn alloys, the addition of Zn (2) in magnesium increased strength. Also, since the maximum solubility of Zn in magnesium is 6.2wt%, a considerable amount of Zn can be retained in solid solution in magnesium alloys by rapid solidification. In addition, Ca is known (3) to be one of the most potent alloying elements for refining the microstructure and precipitates in magnesium alloys, and also to improve mechanical strength and corrosion resistance."

Jan 1, 2000

By Hideki Yamamoto, Shigeno Matsumoto, Junji Shibata

"Some fundamental studies were carried out in order to produce composite powders comprising of two or three metal oxides ~y using liquid-liquid extraction and to develop the control technology of the particle size. The combination of samarium and cobalt was selected as the two component composite powders. Both stripping and crystallization occurred at the same time by emulsifying the organic phase loading the two metals extracted with Versatic Acid 10 and the aqueous solution containing oxalic acid. The effect of aqueous pH, oxalic acid concentration and agitation speed was examined on some properties such as crystallization percent, particle size and shape of each metal oxide powders obtained in this process. The analysis by using EDX showed that the two metal oxides were distributed uniformly.IntroductionComposite metal and metal oxide powders with high purity are indispensable as industrial materials in the fields of electrical engineering, electronics and metallurgy. It is difficult to mix metal powders or metal oxide powders uniformly for the production of alloy powders. If insoluble metal salts are allowed to collect as crystallization products in the crystallization-stripping process, the conventional melting and crushing process can be avoided. After mixing of the organic phase containing metals in fixed composition, fine metal and metal oxide powders of alloy composition are produced by using a crystallization-stripping method. Versatic Acid 10 and D2EHPA, both acidic extractants, were chosen in this experiment, and the metal oxide powders were produced by using oxalic acid as a crystallization reagent. Mixed metal oxalates containing samarium and cobalt were precipitated from the mixed organic phase containing these metals. Furthermore, the physical properties of the powders, such as particle size, shape and thermal decomposition, were measured in order to evaluate them for industrial purposes."

Jan 1, 2000

By Hongbo Zhu, Kun Yang, Jingyan Jia, Jinhui Peng, Libo Zhang, Yi Xia

"Titanium dioxide is broadly considered as the most potential useful photocatalytic material. In this work, titanium dioxide was synthetized by microwave solid-state method and characterized by thermogravimetry-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The result demonstrates that through microwave solid-state synthesis, we can obtain uniform size and anatase TiO2 photocatalyst, with the precursor being Ti(C2O4)2·2H2O. And its degradation kinetic parameter of MO can reach to 0.21232.IntroductionSince Fujishima and Honda found the photovoltaic property of titanium dioxide TiO2 [l], it has been widely used in the field of pollutant degradation, virus killer and environment protection [2-5]. Compared to other semiconductors, TiO2 has the advantage of low toxicity/cost, chemical stability, excellent photocatalytic activity, and long lifetime of electron/hole pairs, thus it is considered to be a most potential useful photocatalyst material [ 6]. Solid-state synthesis of oxide nanoparticle is a new method developed in recent years, which not only overcomes the shortcomings of easily aggregation existing in traditional hydrometallurgical process, but also fully demonstrates the unique technologic advantages of without solvents, high yield, easy control, less environmental pollution in solid-state reaction [7-11]. Researches show that the new method of microwave synthesis shows a lot of advantages such as fast reaction rate, efficient, high purity of product, uniform morphology, energy-efficient, and nonpolluting [12-15].In this work, we associated microwave heating and solid-state synthesis to prepare TiO2 photocatalyst material. Its photocatalytic activity was studied in the degradation of MO queous solution. Meanwhile, the formation process as well as the crystal structure and morphology of the synthesized powders were characterized by means of chermogravimetrydifferential scanning calorimetry (TG-DSC), X-ray diffractometry (XRD) and scanning electron microscopy (SEM) techniques."

Jan 1, 2014

By Mei Song, Qingyu Deng, Xuewei Lv, Lu Liu, Chenguang Bai, Meilong Hu

"The carbochlorination of several silica materials was carried out in the temperature range from 900 °C to 1200 °C. In this study, silica oxides and gaseous chlorine with carbon as reductant were used. The optimal carbon silica mole ratio in different temperature was calculated by Factsage software and the results showed that the optimal values are 1.2, 1.4, 1.6, 1.8 at 900 °C, 1000 °C, 1100 °C, 1200 °C, respectively. According to the experiments, the chlorination ratios of several silica materials were increased with temperature increasing. In the same temperature, the chlorination ratio of diatomite is the maximum and the chlorination ratio reaches 79%% when C/SiO2 reaches 3 at 1100 °C.1, IntroductionPolycrystalline silicon is the main material to manufacture the silicon polished section, solar battery[1] and high purity silicon wafers[2], also which is the most basic function material of semi-conductor industry, electronic information industry and solar photovoltaic battery industry[3]. The conventional manufacturing process of polycrystalline silicon would be divided into three parts: the improved Siemens method, which was introduced and became the main process to produce the polysilicon products in China. Silane method and fluidized bed method. Silicon tetrachloride and chlorosilans have been employed as by-products in several fields like electronic, telecounications and metallurgy[4-6]• At present, the main applications of silicon tetrachloride include production of trichlorosilane by catalytic hydrogenation, synthesis of fumed silica and ethyl orthosilicate, production of optical fiber grade silicon tetrachloride.The conventional routes for the silicon tetrachloride production have been reported, including the direct chlorination and the chlorination process of ferrosilicon, abandon catalyst and silica[7]."

Jan 1, 2013

By K. Morsi, S. K. Kassegne, A. El-Desouky, K. S. Moon

"Current Activated Tip-based Sintering (CATS) is a new process for the powder-based fabrication of macro, micro and possibly nano-scale features and shapes. This new and unique process enables selective sintering of powders by localizing electrically activated sintering conditions through a stationary or moving electrically conducting tip. We present preliminary experimental results on the effect of tip size in the CA TS process as well as the effect of initial powder particle size on the sintering behavior of nickel powder.IntroductionSpark Plasma Sintering (SPS) has been the center of attention of numerous researchers due its noticeable advantages over conventional sintering techniques such as rapid heating rates, lower sintering temperature and shorter holding times. Research on SPS has been applied on a wide variety of materials such as pure metals [ 1], ceramics [2], composites [3], nano-materials [ 4], biomaterials [ 5], shape memory alloys [ 6] and many other material systems. However, it has been mostly limited to bulk materials with simple shapes with a few exceptions ofresearch efforts where the effect of electric current was combined with metal forming processes such as spark plasma extrusion [7,8] and electric rolling of powders[9]. In this paper a novel process (Current-Activated Tip-Based Sintering (CATS)) is discussed where electric current and pressure are applied simultaneously through a small conducting tip (stationary or moving) over a conducting powder compact. This process has the potential advantages of sintering complex geometries with minimum energy requirements as unconventionally high current densities can be achieved due to the small contact area between the tip and the powder compact. Furthermore, by controlling the tip size, it can be possible to sinter features on the macro-, micro- and even nanoscales."

Jan 1, 2011

By Noboru Masuko, Sachiko Ono

"The structure and composition of anodic films formed on aluminum in a borate solution have been investigated by using TEM and SIMS with respect to the effect of current density and electrolyte temperature. The film is composed of a boron-containing outer layer and a boron-free inner layer with disc-like crystals present at the interface. The thickness of the film formed at constant current density up to an identical voltage, decreases with increasing current density. The thickness increases remarkably with elevated temperature. The transport number of Al3+ estimated from the thickness ratio .of the cuter to the inner layers is 0.4 when the film is formed at the current density of 20 Am-2 at 60°C. It increases slightly with increasing current density and decreases significantly with increasing temperature. Content of boron in the outer layer increases 1.5 times when current density .increases 10 times. These changes in film structure and composition with electrolysis conditions must have a significant role in the determination of electric properties of anodic alumina films as a capacitor material.IntroductionThe growth of anodic alumina film in ·a neutral electrolyte proceeds at both film/electrolyte and film/substrate interfaces giving a duplex structure. The oxide layer formed at the former interface includes electrolyte anions while a-pure alumina layer is formed at the latter interface. The thickness ratios of each layer respectively represent transport numbers of Al3+ and 0 2 - (1). The film thickness and the incorporated anion content as well as transport numbers of both ions must affect the dielectric properties of the film as a capacitor material. However, the correlation between film structure and electrolytic conditions is not fully understood (2). For the further clarification of anodic film growth mechanism, more detailed characterization of anodic films in relation to electrolytic conditions is advantageous. In the present paper, therefore, the effect of current density and electrolyte temperature on the microstructure and composition of anodic barrier films formed in a neutral borate solution was studied. The films were characterized by direct observation using transmission electron microscopy (TEM) and depth profiles of constituent elements obtained by secondary ion mass spectroscopy (SIMS)."

Jan 1, 2000

By Jie Li, Thomas A. Rawdanowicz, W. J. Collis, S. Venkatraman, S. Iyer

"InSb being the lowest band gap. material amongst the 111-V semiconductors with low effective mass has long attracted research interest, due to its potential application in far infrared devices and for high speed circuit elements. In this paper, we report, for the first time, Te-doping of InSb on GaAs substrate using SnTe doping source with molecular beam epitaxy (MBE) technique and its electrical characterization. The undoped epilayers are n-type in the temperature range of 10 K to 300 K investigated. The room temperature (RT) mobility as high as 64,810 cm2/V·s (1.9x1016 cm-3) have been measured on a 4.8 µm thick epilayer. Sn Te doping at different doping levels were investigated. 5. 7 µm thick doped layers with RT carrier concentrations ranging from 2x1016 cm-3 to 3.2x1018 cm-3 with corresponding full width at half maximum (FWHM) of x-ray (400) rocking curve varying from 170-200 arc-seconds have been achieved. The Hall mobility of 20,000 cm2/V·s at 1.3xl018 cm-3 carrier concentration was obtained indicating that SnTe is a good candidate as source material for n-type doping of InSb.IntroductionThe thin films of InSb and InSb-based alloys have found considerable interest because of potential applications in III-V semiconductor-based infrared optoelectronic devices1• In addition, the advantage of the small effective mass and the consequent high mobility can be utilized in high frequency and high-speed circuit devices2 InSb can also be used in magnetoresistive sensors for position sensing3. Epitaxial InSb films grown by MBE may be doped n-type with Si or Sn, or with the group VI elements, namely, S, Se, or Te. Of the group VI elements, Te may be advantageous because of its relatively low vapor pressure. However, the vapor pressure is high enough to have sufficient memory effect during MBE growth. Hence different telluride compounds such as GaTe45, PbTe6 and Sb2Te37 have been used as the dopant source for Sb-based compounds. SnTe has also been used as a successful n-type dopant in the MBE growth ofGaSb8 But, to our knowledge, there is no report on the investigation of SnTe doping of InSb. In this paper, we report the first doping characteristics of SnTe in InSb layers grown on GaAs substrate."

Jan 1, 1998