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By Adrian C. Deneys, David G. C. Robertson

"Fluid flow phenomena on the surface of a molten slag have been documented using video photography in a laboratory scale D.C. arc furnace. The flow on the surface of the slag appeared to be electromagnetically influenced. This was confirmed by varying the position of the anode, which changed the direction of flow on the surface of the slag. Temperature measurements in the bath also confirmed the change in the directional nature of the fluid flow induced by the arc.During some periods, solids were fed into the arc attachment zone (AAZ) down the center of the hollow graphite electrode. Significant movement of the arc around the basal annular surface of the hollow electrode takes place. The point of attachment of an arc on a hollow electrode was more variable than an arc attached to a solid graphite electrode. Video images showed that the solids were rapidly incorporated into the bulk of the slag. Temperature measurements confirmed the existence of a superheated slag layer at the slag-gas interface, which allowed the solids to be rapidly incorporated into the melt.This work has been conducted to study fluid flow, temperatures, and solid behavior during feeding, in the arc attachment zone of a D.C. arc furnace. The work also has relevance to optimizing furnace design for pyrometallurgical slag cleaning processes."

Jan 1, 1999

By T. T. Chen

Hydrometallurgical products are difficult to characterize because of their fine grain sizes, heterogeneity, often amorphous structures and water soluble or hydrated constituents. Such products are advantageously studied using complementary mineralogical techniques including >50, ore microscopy, SEM-EDX, electron microprobe analysis, selective leaching and wet chemical analysis to determine the phases and their morphologies, to identify specific element carriers, and to elucidate the chemical reactions occurring during the metallurgical process. Sample preparation is an important consideration for these materials. For extremely fine-grained particles, or soft and brittle products such as elemental sulphur, the study of loose powder mounts provides information not available from the examination of polished sections. To demonstrate the application of the various mineralogical techniques, commercial zinc roaster calcines and leach residues, copper refinery anodes and anode slimes, and laboratory bornite leach residues were examined in detail. The various sample preparation and mineralogical methods are presented, and the use of these complementary and practical mineralogical techniques to improve the understanding of a particular hydrometallurgical system is discussed.

Jan 1, 1989

By T. T. Chen

Kidd Creek continuously-cast copper anodes are characterized by high levels of Se, Pb and Ag; the anode slimes constituents and their morphologies are controlled by both the anode composition and the casting process. Hollow Cu2Se spheroids and tube-like structures, enveloping Cu-Pb-As oxide and/or Cu2O, are present in the as-cast copper. During electrolysis, the selenides are liberated from the copper and accumulate in the slimes layer; the Cu2O and Cu-Pb-As oxide react rapidly with the electrolyte to form soluble species and PbSO4. Silver, which is present mostly as a solid solution in the anode copper, is also liberated during electrolysis and reacts with the Cu2Se to form (Cu,Ag)2Se. The ultimate composition of the selenides in the slimes layer depends mostly on the Ag and Se contents, but various other elements, including Au and Te, are also structurally incorporated. Although the selenides are the major Ag carrier, metallic silver also is present. A thin layer of Cu2O crystals sometimes forms at the copper surface, and may affect anode passivation. Copper sulphate is a common constituent and serves to agglomerate the slimes. Copper sulphate is present on both passivated and non-passivated anodes, but that observed on the passivated metal is present as a thick compact layer. Copper powder is associated with CuSO4.5H2O only on passivated surfaces.

Jan 1, 1987

By James C. Barker

Near Rainbow Mountain in the east-central Alaska Range an ultramafic complex forms a sill-like intrusion composed of dismembered bodies exposed along the south side of the Denali Fault and Broxson Gulch Thrust. The complex comprises dunite and peridotite with lesser gabbro, which together exhibit poorly defined, steeply-dipping compositional layering. The complex hosts four types of copper-nickel occurrences which have characteristic platinum-group elements (PGE), gold, and cobalt distributions. Three of the occurrence-types are considered to have formed as a result of primary mineral segregations which developed during intrusion of the complex. The fourth type of copper-nickel occurrence formed as a result of post-magmatic hydrothermal fluids at intrusive contacts. Scanning electron microscope examination indicates that PGE occur as micron-size telluride and arsenide minerals.

Jan 1, 1987

By Don Ibana

Supported by the Minerals Council of Australia (MCA) through the Minerals Tertiary Education Council (MTEC), three Australian universities–Curtin University, Murdoch University and the University of Queensland–have formed the Metallurgical Education Partnership (MEP) to jointly develop and deliver an engineering design capstone unit–Metallurgical Process and Plant Design–in their respective undergraduate programs in extractive metallurgy, in order to enhance the students’ educational experience. A unique feature of the program is the close interaction of the students in all three universities and a significant involvement of industry professionals. Now in its sixth year, it is clear that this unit is achieving its objectives

Jan 1, 2014

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

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

Jan 1, 2012

By T. R. A. Davey

The technologies of lead, zinc and tin extraction have made varying degrees of progress over the past twenty years. Producers of all metals have faced increasing demands for reduction of pollution and environmental degradation, and the level of public concern is rising rather than abating. New processing techniques must therefore be not only economically feasible, but politically acceptable, even when the demands of "conservationists" and ?environmentalists? are unreasonable. A new generation of processing techniques has come into being, which do not rely on an expensive sintering stage, nor use metallurgical coke, which is difficult to make without serious pollution. They utilise intense reactors, conveying materials from one stage to the next preferably within an enclosed space, obviating fume emissions, and avoiding heat losses as far as possible. The acceptability of the new techniques? is increased if lowgrade or complex materials can be treated, along with a variety of returns and wastes. In addition, a good selling and servicing organisation seems to be as important as good process technology in determining the spread of the new processes. In the field of pyrometallurgical refining the need is for more general application of several recently developed techniques rather than a search for alternatives to the existing process technologies. However, there is a need for fundamental work investigating the phenomenon of oxygen anode overvoltage in the electrolytic zinc process, in order to make progress in the further reduction of energy consumption. There is also scope for further development and application of vacuum distillation to up-grade thermally produced zinc. This paper presents a personal view of processes which should be developed to overcome existing problems, as we approach the turn of the century,

Jan 1, 1990

By N. D. Schupp

The Doe Run Company's Herculaneum, Missouri lead smelter has existed in continuous operation since 1892. Throughout the history of the plant extensive developments have been made to improve throughput, increase productivity, decrease operational costs and improve technology, while remaining an environmentally responsible producer of high quality primary lead in the international market. This paper provides an overview of the Herculaneum smelter, focusing on the most recent configuration of the operations. The paper includes discussion on all the aspects of primary lead production at the Herculaneum smelter.

Jan 1, 2000

By Stephen Gale, David Clarry, Edmund Smith, Jon Feldman

"In 2006, a Canadian steel maker embarked on an ambitious initiative to become “Best in Class in Energy Management”. This initiative provides the framework for this paper, with some augmentation from other energy management projects carried out by Hatch. The initiative focused on identifying energy/GHG management improvements leading to low-cost implementation of energy savings or GHG emission reduction. The key components of the approach were:• Review site energy management practices and benchmark internationally.• Review best technical practices and benchmark against public energy intensity data.• Conducted a site-wide Energy Assessment and physical review of operating areas.• Facilitation of on site-workshops with staff to prioritize savings opportunities, as well as identify and remove implementation barriers.• Development of an Energy Management Action Plan for implementation of improvements.Most organizations can produce, with relative ease, a list of ideas for saving energy, implementing them is the challenge. This paper addresses these issues as well as the profitability of the energy efficiency improvements and the consequences for GHG emissions.IntroductionWhen one of the authors was an undergraduate engineering student at the University of Cape Town in South Africa, the technical drawing instructor made a statement that was both humorous, and mildly profound. He claimed that the most successful engineer is one who is both lazy and diligent. Lazy, in the sense that the engineer is constantly on the lookout for an easier, more efficient, way to do something. Diligent, in the sense that the engineer will work tirelessly to come up with a good technical solution for the easier way. This paper, somewhat of an anomaly in a compilation of technical proceedings, hopes to break the mould a little, and to show a “lazy-diligent” way of reducing the carbon emissions from an industrial facility, using a steel plant as an example."

Jan 1, 2008

By Anupam Madhukar

The essence of an atomistic unified kinetic model of strained thin film growth and defect initiation is presented along with a comparison of its consequences obtained from computer simulations with experiments. Within the competing kinetics of a strain dependent activated incorporation of atoms and an asymmetry between upwards and downwards inter-layer migration, the model provides a consistent description of 2D versus 3D morphology evolution accompanied by the appearance of surface vacancies and steps at no energy cost. The correlated migration of these precursor defects offers an atomistic mechanism for the emergence of surface half-loops from the growth front (thus accounting for configurational and thermal entropy) governed by activation energies closer to their correlated motion under the evolving strain fields and thus substantially less than those calculated with respect to the perfect crystal as the reference state. The essential mechano-chemical nature of the problem is compared and contrasted with the historical literature of such phenomenon as precipitation hardening and sintering in metallic and ceramic composites.

Jan 1, 1994

By D. Q. Cang, G. Duan, H. X. Li, H. Bai

"Life cycle assessment (LCA) is a valid environmental evaluation method and enterprise environmental management tool used in industrial ecology areas. In this paper LCA was newly used to evaluate the environmental impact of manufacturing of alumina by Bayer process in china from two aspects of logistics and energy flow, GaBi software acted as analysis tools with evaluation model established, and several environmental impact assessment criteria were selected based on the actually typical date of Bayer alumina producing process. Evaluation results show that alumina manufacturing by the Bayer process has a great impact on the global warming and human health of respiration, even roasting process gives rise to the greatest impact of winter fog index. Scenario analysis proposed ways of reducing environmental load caused by Bayer process including: (1) the economic and efficient use of mineral processing technology; (2) optimization of energy use, saving power consumption or the use of new more economical source of energy; (3) actively promote the use of innovated technology and equipment in alumina manufacturing and waste such as red mud utilization process.1 IntroductionSince 2002, China is already the world's biggest producer of aluminium, in 2007, China aluminum production has accounted for above 1/3 all over the world, 2009 for 13 million tons and to the end of 2010, China aluminum production is expected increased to be over 15 million ton [1,2,3]. While as the raw material for producing aluminum the alumina production in china has up to 19.46 million tons of the world's total quarter in 2007, by the end of 2009 China alumina production has achieve to 23.78 million tons [4,5]. China has rich bauxite resources with proven reserves about 23 million tons, but the great majority of china bauxite is hard monohydrate diaspore type with low ratio of aluminium silicon, high impurity content and poor aluminum dissolution performance, that cause high energy consumption, long and complex process, high production costs and heavy environment load[6,7]. Before most used alumina production was sintering process rather than Bayer method in china, over the past decade Bayer method has been widely applied instead of sintering process or combination both forming joint process, premise is improving bauxite quality by mineral processing or adding imported rich bauxite mineral[6,8]. In general each ton production of alumina needs bauxite 1.6~2.20t, limestone 0.7~1.7t, soda 0.250kg, fresh water 12.30 cubic meters, in addition to consume large amounts of energy, and emission waste water over 8.0 cubic meters, dust 2.3~5.7 kg, red mud 0.8-1.5 tons. In china Red mud yield nearly 30.0 million tons every year, accumulated stock is approximately 0.2 billion tons, by 2015 accumulative total red mud is expected to reach 0.35 billion tons [9-13].We know aluminium industry and alumina production have produced large waste, make large energy consumption and its environmental impact could not be ignored. Expecting to optimize production processes and achieve resource recycling for this industrial process the proper environmental assessment is very necessary. Currently Life Cycle Assessment (LCA) is generally recognized as the approved tool to achieve the purpose. The essence of LCA tool is to examine, identify and evaluate a kind of materials, product, process, or a system of environmental impact in their whole life cycle. The life cycle of materials or products includes whole process from raw materials obtained to the final disposal, or more ideal with original or other forms of the whole process of recycling [14-17]."

Jan 1, 2011

By Gerald Onyedika, Tochi Onwumere, Martin Ogwuegbu

"The kinetic study for the leaching of iron from cassiterite ore in KOH solution was studied. The effects of KOH concentration, particle size and reaction temperature on the leaching rate of iron were also examined. The results of leaching studies showed that the leaching of iron from cassiterite ore in KOH solution is significantly influenced by the reaction temperature, KOH concentration, and decrease in particle size. The study showed that 90.62% of iron ore was leached in 8M KOH solution at 80°C within 120 minutes. The experimental data were well evaluated using the shrinking model for surface chemical reaction and diffusion control through the product layer. The activation energies for the iron ore dissolution using the two models were calculated to be 32.06KJmor1 and 97.97 KJmor' respectively.IntroductionIn recent times, there has been increasing attention on the kinetic study of mineral dissolution. In most of these studies, the experimental results were analyzed with a suitable shrinking core model under the assumption that the ore is a homogeneous spherical solid phase [1-4]. A study of the dissolution kinetics of a Nigerian cassiterite ore by hydrochloric acid showed that increase in the hydrochloric acid concentration is accompanied with increase in the amount of cassiterite ore dissolved at various times [4]. The optimal concentration was found to be 4.0M HCl, after which there was a decline in the amount of the ore dissolved, which showed that the concentration of the reagent has a significant effect on the leaching rate of the ore. Also in studying the effect of stirring speed on the rate of cassiterite ore dissolution while keeping other conditions constant for 120 minutes, the result showed that the rate of cassiterite ore dissolution was dependent on the stirring speed over a range of 0 to 630 rpm. Above 360 rpm, the stirring speed no longer had any effect on the solid dissolution. The dissolution rates of cassiterite were analyzed using a suitable shrinking model. The results showed that the reaction was controlled by the diffusion of tin through the porous product layer, a reaction order with respect to hydrogen ion concentration of 0.92 M and activation energy of 50.05KJmor'. In another kinetic study on the leaching of a low grade niobium-tantalum ore with concentrated KOH solution the effect ofreaction temperature, KOH concentration, agitation speed, particle size and alkali-to-ore mass ratio on the dissolution rate of niobium were examined [5]. The result of niobium leaching from low grade niobium-tantalum ore with concentrated KOH, solution at different agitation speeds showed that the dissolution rate increased with increase in agitation rate. In the case of particle size effect, the results show that small particles require much shorter time for complete dissolution than the large ones."

Jan 1, 2013

By Sepp Härkki

The energy crisis in Finland after World War I1 together with a sharp rise in the price of energy caused Outokumpu Oy to consider replacing the electric furnace smelting of copper concentrates by some other method. The flash smelting method developed under these circumstances offered a considerable saving of fuel through the utilization of the reaction heat of sulphides and yielded a high recovery of sulphur in the form of acid. The pilot plant testing of the new process was carried out in the years 1947 - 1948. The process was adopted for the smelting of copper concentrates (1) (2) (3) on a commercial scale in 1949 and applied successfullv to the smelting of -nickel concentrates' at the Harjavalta Works in 1959 (4) (5) (6). In 1962 Outokumpu adopted another type of flash smelting where elemental sulphur is recovered from the gases after the thermal decomposition of pyrite in the flash smelting furnace (7) (8): In recent years, the copper-nickel flash smelter and pyrite process have been combined to produce elemental sulphur instead of SO2 from the smelter gases (9) (10). The basic idea of the Outokumpu flash smelting process for sulphidic ores is that the conventional methods with separate roasting and smelting operations are replaced by a combined roasting, smelting and part-converting process carried out in one unit. The heat generated from the exothermic reactions can thus be used for smelting the ore so that only a small amount of additional fuel is needed. The characteristic of the method is also that the dried, fine-grained concentrate is smelted in suspension, which offers the best conditions for rapid reactions. The recovery of waste heat from the furnace off-gases had been considered already in the original flash smelting system. A

Jan 1, 1976

By Roger Altman

The solubility of copper in primary spinel crystals encountered in reverberatory slag samples has been determined by electron microprobe analysis. These spinels, which ranged in composition from 22% A12O3 to pure magnetite, contained small quantities of dissolved copper (0-0.4%). Based on literature data it was estimated that the solubility limit of copper in solid magnetite is no greater than about 1% at 1200°C and about 2% at 1250°C. However, it was found that practically every spinel crystal examined contained significant amounts of matte inclusions. Further examination of converter slag revealed large quantities of irregularly shaped precipitated magnetite crystals which contained a large proportion of copper inclusions. Additional experimentation showed that the total copper content in reverberatory slag samples was greater than the sum of the estimated en- trained plus dissolved matte in the slag. This difference is believed to be significant and is due to the presence of matte inclusions in the spinel crystals. In the present reverberatory slag samples these inclusions accounted for about 1/2 of the amount of sulfide directly entrained in the slag.

Jan 1, 1976

By Jorge Gibson, P. Chris Pistorius, Megha Jampani

"The main reason for the significant carbon intensity of integrated steelmaking (approximately 1.8 tons of CO2 per ton of steel) is the use of carbon-based reductants in blast furnace ironmaking. Several changes to blast furnace ironmaking have been proposed as ways to reduce carbon intensity and cost. A conceptually simple two-zone blast furnace mass and energy balance can be used to quantify the expected impact of such process changes on coke rate, carbon intensity, and productivity. Examples to be discussed include top gas recycling, combining lower blast temperatures with increased coal injection to produce a rich top gas, using prereduced feed, and tuyère injection of natural gas. The use of the operating window – which illustrates how allowable flame temperatures and top-gas temperatures constrain feasible oxygen enrichment levels – is illustrated. Increased use of natural gas would lower the carbon intensity of blast furnace ironmaking.IntroductionBecause of the significant carbon intensity of steelmaking (approximately 1.8 tons of CO2 emitted per ton of steel produced) and the high production rate of steel (more than 1.4 billion tonnes per annum), steelmaking is responsible for a large percentage, approximately 6.7%, of world anthropogenic CO2 emissions [1]. By far the largest input of the carbon into conventional steelmaking is as coke, which is essential to blast furnace ironmaking. A typical fuel rate for blast furnace ironmaking is 450 kg of fuel per tonne of hot metal (THM). (""Fuel"" includes coke and injectants which partially replace coke; pulverized coal and natural gas are typical injectants.) Assuming the fuels to contain 90% carbon on average, and since nearly all of this carbon exits the steel plant as CO2, a fuel rate of 450 kg is equivalent to a CO2 intensity of 1485 kg/THM – by far the largest part of the total CO2 intensity of steelmaking.Blast furnace ironmaking is expected to remain the main source of new iron units; this paper gives some estimates of the extents to which further reductions in carbon intensity from blast furnace ironmaking is possible. A recent European assessment suggested that blast furnace process intensification options such as increased pulverized-coal injection or natural gas injection would yield only modest energy savings [2]. However, if the focus is on CO2 emissions rather than on total energy use, there would be an advantage to using fuels – such as natural gas – which have lower carbon contents relative to energy content."

Jan 1, 2014

By Toshiyuki Hashida, Victor M. Lopez-Hirata

"Small-punch tests and determination of fracture toughness JIC were conducted at 4 and 77 K on new cryogenic JN1, JJ1 and JK2 austenitic stainless steels, after isothermal aging. Equivalent fracture strain ?qf determined by measuring the reduction of thickness in the small-punch test specimen. A linear dependence of JIC on ?qf was found in these new materials. Regression analysis of experimental data produced the following linear relation JIC = 1304.1 ?qf + 8.09 [kJm-2]. An analysis of present work relation was pursued on the basis of material properties and evaluation method of he. Results showed that the slope value has a strong dependence on material yield strength and JIC evaluation method. This linear relation is useful for the evaluation of fracture toughness JIC, measuring the equivalent fracture strain ?qf by means of small-punch test. Thus it can be useful for assessing the degradation of fracture toughness in small areas such as, the heat-affected zone in welded components.IntroductionCryogenic structural materials for superconducting magnets of fusion nuclear reactor are required to possess a good combination of strength and toughness. The mechanical properties are required beyond the capability of conventional austenitic stainless steels [1]. New cryogenic JN1, JJ1 and JK2 austenitic stainless steels were developed by the Japan Atomic Energy Research Institute (JAERI) [1]. The structure of superconducting magnets is constructed by welding of 200 = thick plates of these steels, which are solution treated at high temperatures and then water-quenched to avoid intergranular precipitation. However, the welding process involves heating and cooling [2], which cause microstructural changes in both base metal and weld. In this heterogeneous microstructure, it is important to estimate the fracture toughness of these materials at cryogenic temperatures. Therefore, it is necessary to evaluate the effect of aging process on the fracture toughness behavior of these new steels. To determine the cryogenic fracture toughness, the elastic-plastic JIC value has been co=only used [2]; however, the specimen size is much larger than heat-affected zones in welded components. Small-punch (SP) testing method, employing miniature specimens, has permitted to evaluate the fracture toughness behavior at different temperatures in different nuclear reactor materials [3,4]. Mao et al. [5,6] and Misawa et al. [7] found a linear relation between JIC value and equivalent fracture strain ?qf, determined by SP method in non-ferrous alloys and ferritic steels at room temperature and austenitic stainless steels at 4 and 77 K, respectively. So that, this kind of correlation would be very useful to assess the fracture toughness JICe values by means of SP test in small zones of welded components."

Jan 1, 2012

By F. G. Caballero, J. L. Gonzalez-Carrasco, S. Barrius, H. Carreon, M. Lieblich

"The grit blasting is a low-cost technique successfully used to enhance mechanical fixation of the implants through increasing their roughness. As a result of the severe plastic surface deformation, it produces subsurface effects such as grain refinement, hardening and compressive residual stresses which are generally evaluated with destructive techniques. In this research work, non-contacting and contacting thermoelectric power measurements are performed in blasted 316L VM and Ti-6AI-4V specimens using Ah03 and Zr02 particles which yield a coarse and a fine rough surface, respectively. This study correlates the microstructural changes induced by the grit blasting treatment and the limitations and advantages of each of the nondestructive thermoelectric techniques based on the Seebeck effect used to evaluate these biomaterials.IntroductionIt is well known that surface properties play an important role in metallic materials used in bio-medical applications. Since the biological response is correlated directly with surface properties it is comprehensible the intense activity in superficial modification by physics or chemistry methods in this field. Grit blasting, one of the most popular surface modification of metallic biomaterials, enhances the mechanical fixation of the implant through the increase in roughness [1-3]. Roughening is developed by bombarding the surface with a high-velocity jet of ceramic particles, being the final roughness a function of the processing parameters (pressure, distance, time, ... ) and blasting particles (nature, shape, size). As the plastically deformed surface layer tries to expand relatively to the intact interior of the specimen, residual compressive stress gradients develops perpendicular to the surface at shallow depths with a maximum value at a depth in the range of 5 to 60 µm. This surface treatment also may cause subtle variations in the subsurface material properties, such as increased hardness and grain size refinement, which are consequences of the significant plastic deformation through cold work. Blasted affected zones may extend to a depth of up to about 200 µm. The subsurface hardening and the near-surface compressive stress gradient playa beneficial role by retarding fatigue crack nucleation and further growth, ultimately extending the fatigue life of the metallic part [4]. In this work, two non-destructive thermoelectric techniques (NDTT), the non-contacting and contacting thermoelectric power measurements were used to analyze the subsurface induced changes on blasted Ti-6AI-4V and 316L VM specimens using Al2O3 and Zr02 particles. Detailed information on the microstructural induced effects and subsurface mechanical properties were published elsewhere [5-8]. Here the nondestructive evaluation of the involved microstructural changes is used to assess the global subsurface damage. Advantages of using nondestructive techniques during manufacturing are envisaged."

Jan 1, 2012

By Shadia J. Ikhmayies

"Cadmium telluride (CdTe) is a very interesting material that has many applications. Thin films of p-type CdTe can be used as the absorber layer in the heterojunction CdS/CdTe thin film solar cells in which n-type cadmium sulfide (CdS) works as the window layer. A review of the photoluminescence (PL) spectra ofp-type CdTe thin films prepared by different techniques was performed. The presence of defects and impurities such as oxygen and chlorine influence the PL spectrum. Copper and other dopants change the PL spectra and enhance the defects band. Chemical-heat treatment especially with CdCh is known to improve the quality of CdTe thin films because it decreases the Cd vacancies and quenches deep traps, so it enhances the PL signal. A discussion of chemical-heat treatment especially with CdCh, the effect of the ambient atmosphere, and that of the measuring temperature is performed.IntroductionCadmium telluride (CdTe) is a II-VI compound semiconductor that has a cubic zincblende (sphalerite) structure with a lattice constant of 0 A4~11]. Other than all of II -VI semiconductors, CdTe can be made both n- and p-type. But due to self compensation it is not easy to get p-type CdTe films [2]. Polycrystalline CdTe thin films are interesting because they have a lot of applications. Most of the problems associated with the use of these films are attributed to inhomogeneity, self-compensation, and the difficulty of forming a stable and lowresistivity ohmic contact [3]. CdTe technology has been established for a large number of applications, including solar cells, optical and nuclear detectors, and thermal- and radiationimaging devices [3]. At present, the highest demonstrated conversion efficiency for a CdTe based heterojunction (ID), with CdS as a window layer, is 16.5% [4, 5]. CdTe thin films can be prepared by different experimental techniques, such as thermal evaporation [l], electrochemical deposition (ED) [3], close-spaced sublimation (CSS) [3, 4, 6], physical vapor deposition (PVD) [3], chemical molecular beam deposition (CMBD) [7], and close space vapor transport (CSVT) [8].The objective of this paper is to make a review of the photoluminescence (PL) spectra ofp-type CdTe thin films prepared by different techniques and discuss the factors that influence the PL spectra. The composition of the film is very interesting in determining its PL spectrum. Different kinds of defects, impurities and dopants have their finger prints in the PL spectrum. Deposition techniques and deposition parameters such as the deposition temperature and ambient atmosphere also have their influence. Heat and chemical treatments which are known to improve crystallization and reduce the defects change the PL spectrum."

Jan 1, 2013

By Jie Li, Shu Yang, Zhongliang Tian, Xun Hu, Yanqing Lai, Shaolong Ye

The electrolyte with high solubility for Sc2O3 is very important to realize the preparation of Al-Sc master alloy by the molten salt electrolysis. The solubility of Sc2O3 in K3AlF6- Na3AlF6-AlF3 melts is determined with an isothermal saturation method. The effects of KR (ratio of K3AlF6 to K3AlF6+Na3AlF6), the concentration of Al2O3 and the temperature on the solubility of Sc2O3 are also investigated. The results indicate that the solubility of Sc2O3 in K3AlF6-Na3AlF6-AlF3 melts increases and then decreases with KR increasing. The solubility of Sc2O3 is 8.698 wt.% in (K3AlF6-Na3AlF6)(KR25%)-18 wt.%AlF3 melts at 940℃. The effect of temperature on the solubility is little, and the values are 8.575 wt.% and 8.762 wt.% respectively when the temperatures are 930℃ and 960℃. The solubility decreases from 8.809 wt.% to 7.058 wt.% as the concentration of Al2O3 increases from 1.5 wt.% to 5.0 wt.% at 950℃.

Jan 1, 2015

By S. L. Pohlman

Physical characteristics of possible importance in the acid leaching of Chrysocolla have been evaluated. Surface area studies and pore size distribution indicate: 1) a large surface area (350 m /gm); 2) an average pore size of 13 or 16 Å , depending upon use of the adsorption, or desorption, branch of the Type IV isotherm in the evaluation; ) the presence of a significant fraction of pores of size less than 15 Å determined by the accumulation surface area method. The initial structure is micro- crystalline on the basis of x-ray powder patterns; the silica leach residue is amorphous and has only 24 m2 /gm surface area, and loses integrity when dry. However, readsorption of copper onto the wet leach residue gives a product with integrity and 100 m2 /gm surface area. Visual observation of the leach residues supports evidence of a non-protective diffusion mechanism of leaching which is well correlated by the shrinking core model previously presented.

Jan 1, 1976