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By A. W. Bryson, S. P. Fox, S. A. Godorr

"This work is an extension of a previous investigation on the development of surface roughness during electrodeposition of copper. A comprehensive model based on diffusion and migration in a force field together with surface diffusion and sticking probabilities is used to generate profiles which are compared to those produced experimentally. The roughness is characterized by using the technique of fractal geometry which is shown to describe both qualitatively and 9uantitatively the development of surface morphology during electrodeposition.The work is extended to the deposition of copper in the presence of various concentrations of thiourea. The development of roughness is observed experimentally on the edge of a thin copper disc mounted between two glass plates. This enables photographs to be taken at various stages during growth. The surface outline is digitized using an image analyzer which enables the fractal dimension to be determined as growth proceeds. As expected, the presence of thiourea at low concentrations produces a fractal dimension which is closer to unity (i.e. the surface becomes smoother).IntroductionThe development of surface morphology during electrodeposition has far-reaching implications for copper plating in the electrowinning and electrorefining processes. Short circuits as the cathode surface grows unevenly require operator intervention in a dangerous environment and imply processing delays, and the inclusion of electrolyte in small gaps in the plated cathode have implications in downstream processing of the cathode. Higher current densities are obviously desirable, as they result in greater production rates, but as shown by Ettel et. al.(l), Harvey et. al.(2), Cook (3), and Harvey et. al.(4), it is not possible to operate near the projected economically optimum conditions because the electrodeposition of copper from sulphate and acid solutions is a mass transfer controlled process. It has been shown (Ettel et. al.(l), Harvey et. al.(2)) that the closer a system operates to mass transfer limiting conditions, the poorer the resulting cathode quality. One solution is to use agitation techniques to increase the limiting current density. Another is to add surface active additives to the electrolyte which has been shown by Ettel et. al.(l), Harveyet. al.(2) and Afifi et. a1.(5) to allow higher rates of production without decreasing cathode quality. The second proposed solution is of interest in this work, since there is very little knowledge of the conditions under which these additives operate effectively, and little fundamental understanding of the mechanism by which they operate. The current work seeks to contribute to this field by correlating a simulation model with experimental results to describe the development of surface morphology in the electrodeposition process."

Jan 1, 1997

By Chai Li-yuan

Anodizing behaviors of magnesium alloys AZ31 at constant applied current, based on the electrolyte solution free of chromate or fluoride, were investigated. The anodizing process was influenced by constituents of electrolyte greatly. Therein, the oxylate salts, which led to the occurrence of the two totally different processes, played a determinant role in anodizing. They were stable and sparking process respectively. The morphology of anodizing film was observed by SEM and the structure of film was analyzed by XRD. During the stable process, a brown thin film was formed, however the sparking process led to the formation of white hard thick film. The functions of some kinds of additives, such as ammonia, glyceryl alcohol and PVP etc were also studied. Some of them had great effect on surface morphology of anodic film and some of them affected stability of anodizing process significantly.

Jan 1, 2006

By W. Kasprzak

Press-fit systems are widely used to seal oil lines in the automotive engine components. In the case studied a ball plug made from the 7075 A1 alloy was inserted into a 319 Al alloy cast component. The oil lines were subjected to the required component service pressure. This paper addresses the analysis of the ball plug/casting hole press-fit performance. The tools used to investigate the plug system included: the SEMIEDS technique for the assessment of the plug and the casting hole wall surface integrity; image analysis methods for the characterization of the ball plug/casting hole interface; matrix microhardness measurements of the plug and casting components; laboratory ball plug insertion, speed and force correlation; as well as the ball shearing mechanism analysis. Laboratory tests indicated that optimization of the aluminum matrix hardness in the 319 A1 alloy cast components resulted in considerable improvement of the press-fit system sealing properties.

Jan 1, 2002

By Yunhua Gan, Xiaowen Chen, Yang Tong

Experimental studies of electro-spraying were carried out using ethanol as fuel in a microcombustor under combined electric field. And the effects of different electro-spraying modes on the combustion efficiency were analyzed. Results showed that when ring electrode potential was invariant, there were four different electro-spraying modes with the variations of nozzle potentials, which were varying with the flow of ethanol. The cone-jet mode was the stablest one during the whole experimental process. The atomized ethanol was ignited and combusted stably near the steel mesh, the combustion efficiency increased firstly and then decreased along with the increasing of the equivalent ratios, reached the maximum values when the equivalent ratio equal to 1.0. And the maximum values were the highest at the cone-jet mode, and the lowest at the pulsed-jet mode.

Jan 1, 2016

By Gunther Schimmel

Ag exudation in four different alloys (Ag-Cd, Ag-Sn, Ag-Sn-In and Ag-Zn) is characterized. The amount of exuded material is correlated with the volume increase due to oxide formation in dependence of the alloy concentration and different densities of the oxide and matrix phases. It is shown that all four alloys show similar amounts of volume increases, but different amounts of exuded material. It is concluded that internal stresses due to the volume increase cannot be the dominant driving force for Ag exudation. A gradient in the chemical potential of Ag that originates from the O concentration gradient inherent to internal oxidation is suggested as driving force. The exudation behavior is thus governed by the variation of the activity of Ag in the Ag fcc phase in the Ag-Me-O system that differs between the alloying systems.

Jan 1, 2010

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 Alan DonaldsoN

Plasma Quench production of titanium is the thermal dissociation of titanium tetrachloride into gaseous titanium and chlorine followed by rapid quenching to prevent back reactions. Titanium tetrachloride dissociates into titanium and chlorine atoms at 5000 K. Expansion through a Delaval nozzle accelerates the gas to supersonic speed cooling it very rapidly. Cooling rates are as high as 7exp 1 0 Kelvins per second. Injected hydrogen reacts with condensed titanium particles to form titanium hydride and with the chlorine to form hydrogen chloride. We have produced titanium powder at 20 kglh in a continuous reactor. Costs are projected to be lower than the Kroll Process at large enough scale. Most of the cost reduction would result from elimination of magnesium as a reducing agent and much lower capital costs.

Jan 1, 2001

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from the University of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

By Richard L. Summers

The shaped charge has proven in various military and industrial applications to be an effective penetrator of materials. Upon initiation a detonation wave traverses the explosive billet, collapsing a metallic liner and creating a jetting process. From multiple non-simultaneous flash radiographs of the jet in free flight, the observer can study the collapse, formation, and growth of a shaped charge jet. Digitization of a particulated jet's position and shape from the radiograph into electronic storage files provides the experimentalist with an efficient basis for data reduction. With the aid of a simple personal computer, one can in a matter of minutes generate a wealth of information concerning jet formation after initiation and thus gain insight into the quality of its manufacture, design, and assembly. This paper will in detail explain the methods in place for fully automated data reduction of radiographic films. Methods of computer aided digitization of particulated jets and analysis of physical jet characteristics and performance will be discussed.

Jan 1, 1992

By David J. Howard, Christine Broadbridge, David C. Paine

"High pressure vapor/solid reactions offer an opportunity for novel synthesis and processing of thin film materials and structures for electronic, optical, and magnetic applications. In this paper we review the use of two high pressure techniques that operate from 25 to 1000 atm (2.5 to 100 MPa) to fabricate thin film oxide structures from Si1-xGex deposited on Si wafers. High pressure synthesis enables temperature-independent control of reaction rates in the oxidation of this multicomponent semiconductor system and hence offers the opportunity to form thennodynamically metastable Si1-xGex<h from the alloy. The thermodynamics of the Si-Ge-0 system are reviewed and a method is described that utilizes selective chemical reduction (via H2 gas) of Si1-xGcx<h to form Ge precipitates in an SiO2 matrix. IntroductionAlloys of Si1-xGex grown epitaxially on Si substrates by chemical vapor deposition (CYD) and molecular beam epitaxy (MBE) have been used to create high performance microelectronic devices1. These devices show improved performance over conventional Si technology because they exploit the Si/Si 1-xGex band-gap discontinuity and take advantage of higher hole mobilities in the Ge containing alloys. While a range of devices based on heteroepitaxial systems have been demonstrated, the Si1_xGex alloys are of particular interest because they are most closely compatable with standard Si device processing. One disadvantage of Si-based materials systems is that they are not typically useful emitters of light. This is important since the use of light (rather than electrons) for transmitting and processing signals into, out of, and within Si-based microelectronics would represent a major technological advance in microelectronics-based communication and computer technologies. Nevertheless, through the use of innovative processing techniques it may be possible to use the Si1_xGex/Si heteroepitaxial system in integrated microelectronic/light-wave technologies."

Jan 1, 1994

By Cristián Araya L.

A dynamic agglomeration, heap leaching, solvent extraction and electrowinning software, called NICO, has been developed in order to either design or simulate copper ore recovery plants. NICO contains a library of routines, each representing a unit operation or piece of equipment, which are assembled like a meccano to match almost any wet plant configuration. Routines include agglomeration or curing either in drums or belts, belt conveyors, heap stacking and reclaiming, heap leaching of oxide, sulfide or mixed copper ores, heap irrigation, drainage, ponds, mixer-settlers, filters, columns, coalescers, tanks, electrowinning cells, pumps, and all connections and related piping. All models are semi- phenomenological, i.e., they include all physical-chemical, mass, thermal, transport equations, which are required to represent as closely as possible the equipment or unit operation. However, operating experience has been incorporated into the model in order to make it simpler, faster and reliable. This experience has been tested in several plants in Chile since 1992. Site meteorological data is simulated also; in this way the model is responsive to weather conditions (temperature, solar radiation, ambient humidity, atmospheric pressure, wind velocity, etc). NICO has been used recently for design and optimization studies in copper plants in Chile like Radomiro Tomic, Collahuasi and Zaldivar. A user-friendly interface allows fast and comprehensive simulations. The entire plant is shown in a single graphic screen, so the user can see all the relevant information, and soft-keys are provided in order to change parameters on-line and watch their effect in final copper production in cathodes. Model also calculates and reports operating parameters, as well as estimated investments and operating costs.

Jan 1, 1999

By Anil Saigal, Jr. Fuller, Said Jahanmir

"All-ceramic crowns, including glass-infiltrated spinel composites, are coming into widespread use because of their superior aesthetics and chemical inertness. This study investigates the residual stresses that are developed in these composites as a result of cool down from the glass-infiltration temperature to room temperature due to slight mismatch in the coefficients of thermal expansion and its effect on the mechanical behavior of these composites. Two-dimensional finite element simulations were performed using an object oriented finite element program OOF. The OOF program is a combination of two programs. The first program, PPM200F, is designed to read an image file such as a micrograph. The individual pixels that constitute the micrograph may be collected into groups and their material properties assigned. PPM200F is then used to create the finite element model/mesh that OOF then reads. The average residual stresses are found to be tensile in the spinel matrix and compressive in the infiltrated-glass. There is large variation in residual stresses and strains from location to location with presence of locations at which the glass is under tensile stress. The crack initiation and initial propagation in glass-spinel composites is at the glass-spinel interface in both the glass and the spinel. The presence of residual stresses can lead to lower crack initiation stresses and degrade the mechanical properties of the composites.IntroductionGlass-infiltrated spinel ceramics are in clinical use as core materials in all-ceramic crowns and as inlays and onlays (1-3). Advantages of ceramic composites include near net-shape forming with high strength in the infiltrated state. Besides, spinel is quite translucent and may potentially be used without a veneer. However, these ceramic composites are subject to damage accumulation from repeat oral contact loading and often fail after a few years of use (4). This paper examines the residual stresses that are developed in these composites, after cooldown from the glass infiltration temperature to room temperature, due to the slight mismatch in the coefficients of the thermal expansion of the two phases."

Jan 1, 2001

By Zhiqian Zhang, Chao Wu, Chao Li, Hongxu Li, Yu Chen, Xiangxin Hao

"In this paper, the life cycle assessment models for automobile lightweight materials including high-strength steel, aluminum alloy and magnesium alloy are developed by Gabi software. The evaluation models and evaluation indicators such as acidification effects, rich eutrophication effect, ozone layer depletion effects, global warming, resource consumption and formation of ozone potential were taken into account. It is shown that the effects of acidification and ozone formation are mainly derived from the run phase of high-strength steel and they have strong environmental impact load. While considering the entire life cycle with materials production phase and resource consumption, the aluminum and magnesium alloy appe art o have large r environmental load than high-strength steel. Base d on the evaluation, some optimization tips are proposed.IntroductionAs the increasing of car ownership, automobile has its two sides. One which is the convenient, efficient and fast traffic vehicle; the other is aggravating energy consumption, emissions and environmental pollution. The car industry faces heavy pressure with energy saving, safety and environmental protection. Nowadays, the main study ways for automotive energy-saving and environmental protection are power system improvement, alternative energy sources and technologies. For limitation of technique, development cycle and market share, the development of car is little progress at this stage and the application has been restricted. And another important way is the lightweight of vehicle. Usually there are three ways to get the lightweight automobile body structure, automobile body structure optimized design, using advanced body manufacturing technology, development and application of lightweight high strength body material.The life cycle assessment (LCA)[1lis commonly used to evaluate environmental factors and potential environmental impacts of products and services. As an environmental management tool of product-oriented, it becomes increasingly popular in industry. In this study, the concept of LCA and GaBi software was used to develop models for the three automotive lightweight materials, evaluate the environmental impact and make horizontal and vertical contrast by choosing variety of evaluation systems and indexes."

Jan 1, 2013

By Ian F. Hughes

"Concepts of an integrated steel plant for sheet products to be built and operating in the year 2000 will be described. The design and operating methodology of this market driven facility will integrate process uniqueness, standardization, manufacturing automation, artificial intelligence and information flow.An integrated steel plant for the year 2000 is defined for this article as one that will be built on a greenfield site and ""started up"" in the year 2000 with a capacity of three million tons per year of flat rolled products ranging from cold rolled and electrical steels to high strength formable steels and a full range of coated products.It may seem that the 21st century and the steel plant we're discussing are far into the future. The startling truth, however, is quite the opposite. As shown in Figure 1, even with accelerated development, a new process on which laboratory development work is begun today might just barely pass through the laboratory phase, pilot plant, and commercial feasibility stages such that it can be considered viable for construction and start up in the year 2000.On that basis, it is very unlikely that this 21st century steel plant will utilize any technology that isn't at least under investigation in the laboratory in 1988. As a result, we recognize that planning and selecting the facilities for this plant is, in fact, a pragmatic rather than futuristic process, and that its main value is in providing a bridge to longer-term predictions."

Jan 1, 1988

By Christian M. Sagedahl

The stringent environmental regulations for air pollution regarding emission control, along with the need of dry concentrates to feed autogenous smelting processes, are enhancing the development of cleaner technologies. Indirect drying of concentrates by a Kvaemer steam dryer is a technology with promising results, reducing dust entrainment to the exhaust gas stream and leading to smaller dust separation units. The Kvaemer dryers are designed for a very high availability, a high-energy efficiency, low amount and velocity of exhaust gases, no SO2, CO or CO, emissions combined with a wide range of satisfactory operating conditions and low total operational costs.

Jan 1, 1999

By Takayoshi Fujii, Mitsumasa Hoshi, Chikashi Suenaga, Yoshiaki Suzuki

"In a bid to renovate its Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, Nippon Mining & Metals undertook major - restructuring efforts since 1993.One of its themes was the shift from a two-flash furnaces operation to a single-flash furnace operation. The shift was successfully completed in 1996 while maintaining the production at the same level (330,000 metric tons per year of copper) by adopting such measures as improvements in pneumatic concentrate dryers, the concentrate feeding system, concentrate burners, the furnace cooling system, and a new cryogenic oxygen plant was constructed.With a view to realizing high matte grade operation (at 65%Cu) and increasing the concentrate feeding rate, further steps were taken the capacity of waste heat boiler was expanded and technical improvements were added, including optimization of the smelting reaction in the furnace shaft. As a result, the smelting capacity, as of the year 2000, has increased to 450,000 metric tons per year of copper.IntroductionThe feed rate to the flash furnace was doubled to 140 t/h from 70 t/h in 1996. Teething problems, as a result of the renovation, were almost solved by the end of 1996, and the operation of the single furnace operation has become stable.The main theme was the shift from a two-flash furnaces operation to a single-furnace operation to maintain the production capacity at the same level, namely 330,000 metric tons of copper per year. Then, in a bid to further renovate the Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, further enhancement of the flash furnace's productivity was planned.The purpose of this plan was to raise the copper production capacity to 450,000 mtpy building on the potentialities of existing plants and without installing new equipment."

Jan 1, 2000

By Yonggang Liu

Microstructure and precipitates in hot rolled low carbon steel sheet by CSP were investigated in this paper. It is pointed out the precipitates in low carbon steel sheet by CSP are different with that by traditional hot rolling. The bainites were found in CSP hot rolled steel sheet by TEM testing and these bainites could maintain in the sheets even after batch annealing. The selected area electron diffraction analyzing indicated that there were many CrB2BN and FeB4BN phases precipitated in hot rolled steel sheet and no AlN grains precipitated. The nitrides forming can limit AlN grains precipitating during the batch annealing processing, and this could do harm to the texture pipeline along orientation line forming with formed properties.

Jan 1, 2006

By João M. S. Rodrigues

The use of sandblasting as a treatment method for conditioning anodes for zinc electro-winning was investigated and compared with conventional fluoride preconditioning. The anodes were made from two different lead-based alloys (Pb-Ag-Ca and Pb-Ag). Laboratory results showed that sandblasting and preconditioning both minimize lead contamination in the zinc and sludge generation. Sandblasting was found to have no aggravating effect on the anode corrosion. The sandblasting treatment was tested on Pb- Ag-Ca anodes on an industrial scale in the celJhouse of a local zinc producer. An unexpected finding of the large-scale tests was that the sandblasting appeared to strengthen the anodes, resulting in reduced warping during handling and operation.

Jan 1, 1996

By Patrick R. Taylor

A kinetic study of the fluosilicic acid leaching of galena was performed under the presence of different oxidants. Fluosilicic acid concentration, agitation speed, concentration of solids and particle size, type and concentration of oxidant, and temperature were the variables studied. Hydrogen peroxide was found to be the most effective oxidant, its effectiveness being proportional to its concentration. As expected, an increase of leaching temperature increased the overall extraction and extraction rate. The same was found by decreasing the galena particle size. It is thought that leaching using hydrogen peroxide is controlled by fluid film mass transfer due to the calculated apparent activation energy. Reaction by-products such as sulfur and sulfur compounds retard the leaching rate. A mathematical model is proposed and compared to experimental results.

Jan 1, 2003

By Charles Zimmerman

The Genesis gold mine, owned and operated by Newmont Gold Co., is located in section 31, T36N, R50E within Eureka County, Nevada along the Carlin Trend of sediment-hosted disseminated gold deposits. Mining commenced in 1986 with present mineable and stockpiled reserves listed at 17,711,000 tons of ore averaging 0.073 opt Au, totalling 1.292 million ounces of gold. Ore is primarily hosted within Devonian calcareous siltstones that have been subjected to intensive argillization and silicification episodes. Additional mineralogic and geochemical features of the Genesis ores include enrichment in iron-oxides, kaolinite, arsenic and antimony; the ore zone is relatively depleted in carbonates and sulfides as a result of supergene and hypogene oxidation. Two major structural zones enhanced the permeability of the siltstones and served as the main hydrothermal conduits within the deposit. Prior to the main ore stage, the host rocks were subjected to metasomatic effects caused by emplacement of the Juro-Cretaceous Goldstrike granodiorite pluton and associated dikes and sills. Micron-size gold occurs in clays, micro-crystalline quartz, and in arsenical complexes. Non-oxidized carbonaceous and sulfidic ores and silica-locked ores result in variable preg-robbing and refractory responses during cyanide recovery. Selective mining and milling has resulted in the successful treatment of the Genesis orebody.

Jan 1, 1988