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By Lichao Ding, Chunhua Liu, Yunnen Chen

"In this paper the simulated acid magenta dye discoloring the reaction process was researched. The results showed that it attained highest decolorization efficiency for acidic magenta simulation dye wastewater when pH 9 and reaction time 10 min. With the initial dye wastewater concentration increased, the decolored rate decreased. The decolored rate in general kept a tendency to increase with the temperature increased. Kinetics researches showed that when pH 9, reaction temperature 20 and 35 ?, the decoloring reaction process for the dyes accorded with the First-order dynamic equation. The decoloring reaction rate constant was influenced by initial concentration of dye wastewater and temperature.1. IntroductionIn China, textile printing and dyeing industry is one of industrial departments which using more water and discharging more wastewater. There is about 7 billion tons of waste water discharge each year, of which 80% from the process of printing and dyeing. Being complex ingredients, high chroma, more toxic substances and severe environment pollution, the treatment of printing and dyeing wastewater becomes problem urgent to be resolved. The traditional treatment methods such as adsorption [1], coagulation [2], biochemical method [3,4], which has advantages of simple equipment, simple operation and mature process, but they can cause waste accumulation and secondary pollution [5,6].Magenta is a kind of organic compounds, which classified into acid and alkaline magenta. Considering the advantages of simple operation, low cost, simple experiment equipment and friendly to environment, acid magenta dyes wastewater was chose as object in this paper. Some parameters such as pH, contact time, temperature and the initial concentration on of simulative acid magenta dyes wastewater were studied."

Jan 1, 2012

By Nozomu Uchida, Uematsu Keizo, Daisuke Shouji

"Grain orientated microstructure was developed for the improvement of ceramic characteristics. Novel polarized light microscopy was developed to examine the grain orientation quantitatively. The degree of grain orientation was estimated from the retardation determined with a Berek compensator. The method was essential to determine a minor grain orientation, which could not be analyzed by means of conventional X-ray measurements. The data were favorably related to ceramics characteristics. The comparis of the ceramics with various degree of orientation was very important to explain the change of ceramic characteristics with processing.IntroductionMicrostructure with grain orientation has a high potential for greatly improving characteristics of ceramic. However, there has been strong restriction on processing and material for developing this structure. It has been crucial to apply forming methods involving high shear such as injection molding1). Grains must have an elongated shape.In recent years, much attention has been paid on the effect of high magnetic field on diamagnetic materials2)3)4), Many ceramic materials are known to be diamagnetic. High magnetic field has a high potential to orient grains. The principal driving force for grain orientation is the magnetic anisotropy of material, which is generated by non-cubic crystal symmetr5). This method of grain orientation is not restricted by grain shape, and can be applied to all materials having non-cubic crystal structure.This study uses alumina as raw materials, and produces alumina ceramics with orientated grain in high magnetic field (10T). Alumina has a magnetic anisotropy due to hexagonal crystal structure. The degree of grain orientation in the green and sintered bodies will be examined and their relevance to magnetic field will be discussed."

Jan 1, 2000

By Ray Y. Lin, Sunil G. Warrier

"Low cost processing of metal matrix composites is an essential requirement for this class of materials to be acceptable in commercial application. In an effort to reduce the cost of processing of metal matrix composites, an infrared pressureless liquid infiltration technique has been developed. The salient features of infrared infiltration are that it is rapid, simple and a low cost process. The rapid processing capability causes very little oxide formation on the alloy resulting in both improved wetting and flow characteristics and reduced oxygen contamination in the composite. Thus, vacuum is normally not required. Using infrared inflltration, aluminum and titanium matrix composites have been prepared under an ambient argon atmosphere. Reinforcements in these composites include carbon fibers, silicon carbide Nicalon fibers and Textron's SCS fibers. Microstructural and mechanical test results indicate that completely consolidated composites with good fiber distribution, limited interfacial reaction and high mechanical properties can be manufactured by this process. IntroductionAluminum and titanium matrix composites reinforced with ceramic reinforcements are strong candidates for numerous applications in the aerospace and automotive industries. Aluminum matrix composites are commonly fabricated by either solid state vacuum hot pressing, liquid state pressure infiltration or squeeze casting [1]. Although liquid state pressure infiltration and squeeze casting has significant advantages over solid state processes, the requirement for pressure makes these composites uneconomical for large scale industrial application. Titanium matrix composites are primarily fabricated by solid state diffusion bonding [2]. Pressureless liquid infiltration can significantly reduce the cost of fabrication in both the composite systems. However, during pressureless infiltration processes, several complications concerning the wetting characteristics and chemical compatibility arise."

Jan 1, 1994

By S. Yokoya

With increasing requirement of steel productivity and quality in continuous casting in the conventional casting system using an immersion nozzle, it is very difficult to establish a reasonable molten flow pattern. In order to overcome this difficulty, we propose a new method of imparting swirling motion onto the flow in the immersion nozzle and to control the flow pattern in the mold. Following results have been obtained during the studies. For the case of slab continuous casting mold: High amplitudes of oscillation with a period of 10 to 15 seconds are observed in the outlet flow of the immersion nozzle and meniscus flow in the conventional casting system, while these phenomena are remarkably suppressed using swirling motion in the immersion nozzle, which leads to very calm and uniform flow pattern at the outlets of the immersion nozzle, in the mold and on the meniscus in the mold; For the case of billet continuous casting mold: (1) heat and mass transfer near the meniscus can be remarkably activated compared with a conventional straight type immersion nozzle without swirl, and (2) Quite different mold flow patterns are observed between the divergent and straight immersion nozzles. Heat and mass transport in the mold using the divergent nozzle is much more reasonable compared to that of straight nozzle. The findings, mentioned above, are very useful to control the flow pattern in the slab, and billet continuous casters. Such effectiveness of swirling flow in the SEN on the mold flow has been put into practical use. As a result, remarkable progress on the quality and production of continuous casting products has been observed in practical application.

Jan 1, 2006

By Ibrahim Yusufoglu, Cem Kahruman, Sedat Ilhan, Ahmet Orkun Kalpakhi

"Scheelite is the main raw material in tungsten production. In hydrometallurgical processes, extraction of tungstate ions into solution is very important. During the leaching of scheelite in oxalic acid solutions, tungsten dissolves as a chelate complex. Scheelite includes impurities along with calcium tungstate. Determination of the dissolution of these impurities is important in the subsequent tungsten production stages. In this study, scheelite was dissolved in oxalic acid solutions and the dissolution of impurities was investigated. The quantities of dissolved impurities were determined by ICP - OES and characterization of the undissolved impurities in the leach residues was carried out by SEM - EDS analysisIntroductionScheelite and wolframite ores are used for the industrial production of tungsten. Both ores are dissolved in acidic or basic solutions, and ammonium paratungstate is obtained as an intermediate product. Prior to crystallisation of ammonium paratungstate, all the impurities must be removed. Among these, Fe, Si, P, Mn, Mg and Mo are classified as ""harmful"" elements and different methods are used for their removal [1]. During purification, solvent extraction, ion exchange, etc. methods are used.Potashnikov et al. [2] studied the dissolution of scheelite in acidic solutions and the effects of stirring speed, temperature and oxalic acid concentration on the dissolution kinetics.There are no works in the literature about the removal of impurities from scheelite ores in oxalic acid solutions. Therefore, the aim of this work was to investigate the dissolution mechanisms of impurities during the leaching of scheelite in oxalic acid solutions. The effects of temperature and oxalic acid concentration on the dissolution were also investigated. In addition, the characterization of the impurities which were not dissolved was studied."

Jan 1, 2012

By Guozhu Ye, Eric’ Burstrom

"Despite of numerous solutions for recovery of zinc from EAF dust have been suggested and tested in laboratory scale over the last three decades, Waelz kiln process is still the most dominating process for treatment of EAF dust. Few of the proposed alternative methods have gone beyond the laboratory tests. This paper will give you insights to some of the concepts that have been pilot tested at MEFOS. The innovative aspects of these concepts will be shown and the major results will be highlighted. These include the following concepts: - Production of a crude zinc oxide product with low halide content for zinc electrowinning using a DC furnace with hollow electrode- Production of a bypass filter dust containing more than 50%ZnO by injection of EAF dust to the electric arc furnace during refining combined with a bypass filter system- Elimination of zinc ferrite by CaO treatment for electrowinning with EZINEX process - Selective reduction of iron oxide in zinc ferrite for simultaneous recovery of ZnO andmetallic ironIntroductionRecovery of zinc from EAF dust is dominated by the Waelz process since EAF dust has been classified as hazardous waste by EPA in the early 1980´s. A large number of alternative processes have been suggested and tested without commercial success due to two major reasons [1]:- High content of chlorine and fluorine for the pyrometallurgical alternatives- High content of ZnOFe2O3 for the hydrometallurgical processesMany innovative concepts for treatment of EAF dust for zinc recovery have been pilot tested at MEFOS in the past 20 years. This paper will review some of the concepts focusing on the two problems mentioned above."

Jan 1, 2008

By José Sancho, Julia Ayala, Purificación García, Begoña Fernández

"Electrofilter dust, a residue generated in the last stage of the Bayer process in the hydroxide aluminum calcination, was characterized to evaluate the alumina that was potentially extractable with sulfuric acid. The process studied aims to produce aluminum sulfate for water coagulant uses, taking advantage of the residues that accumulate in large quantities in the proximity of plants with difficult recycling for storage. Acid leaching is carried out at different concentrations of sulfuric acid, at different temperatures, pulp densities, and times, to dissolve gibbsite and transition aluminas. The result is an aluminum sulfate solution without iron and with commercial specifications.IntroductionElectrofilter dust is a residue generated in the last stage of the Bayer Process [1] in the hydroxide aluminium calcination. The residue is a mixture of alumina and hydrates which have not completed their calcination process.Electrofilter dust, composed by alpha alumina, gibbsite and transition aluminas [2] can be leached in an acid medium by putting most of the aluminium in solution; the remaining residue should be mainly andisolved alpha alumina. In many hydrometallurgical processes, sulphuric acid has been selected as the cheapest and the most effective leachant [3,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]The aim of this study is to determine the effect of temperature, acid concentration and pulp density on the sulphuric acid leaching of electrofilter fines for aluminium dissolution, in order to produce aluminium sulphate for water coagulant uses. This will provide a commercial product and at the same time eliminate the environmental problem created as a result of the storage of large quantities of electrofilter fines in the vicinity of the Bayer plant."

Jan 1, 2008

By Jorge A. S. Tenorio, Girley F. Rodrigues, Joner O. Alves, Denise C. R. Espinosa

"Rock wools are mineral fibers composed of amorphous silicates, due to their thermo-acoustic characteristics this material has a broad consumer market in the construction, automotive, and electric-electronics industries. This work studied the recovery of wastes from ornamental rocks (granite and marble) as partial raw materials in the production of rock wools. Residues from granite and marble cuttings are industrial wastes with considerable production and limited applications. These wastes should be appropriately managed because when discharged in rivers or lakes can cause siltation, and also they can cause serious human health problems, such as silicosis. Samples of produced materials with thickness smaller than 500µm were characterized by chemical analyses, XRD, and DTA. Results showed that the rock wools produced using granite or marble wastes have important properties, especially the melting point. This process decreases the extraction of mineral resources and provides a profitable destination for the ornamental rock wastes.IntroductionThe ornamental rocks industry is a sector with large production of wastes. During the granite and marble extraction processes and specifically during the rocks cutting (see Figure 1), approximately 35 tons of powdered rock per month can be produced. These residues should be appropriately managed, because when discharged in rivers, lakes or watersheds, they can cause siltation. Also, these wastes can cause serious human health problems, such as silicosis [1].Currently, the granite and marble wastes are mainly used in civil construction to produce materials in the form of mortar, bricks and tiles. However, due the current produced volumes and the average growth of world production estimated at 6% per year, new applications for these wastes are necessary [2]."

Jan 1, 2011

By Kazuyuki Kakegawa

"Sintered body of lead zirconate titanate (PZT) was prepared through the spark plasma sintering (SPS) technique. When the mixture of raw materials was calcined at 800°C and sintered at 900°C for 10 min. with SPS technique, the sintered body had almost theoretical density but was a mixture of lead titanate (PT) and PZT. When a calcining temperature of 1100°C was employed, sintered body had a single PZT phase but a lower density. High dielectric constant was obtained for a sample calcined at 800°C, sintered with SPS tecbriique and fired again in the air at 1100°C.IntroductionSpark plasma sintering (SPS) is a recently developed technique for sintering metals and ceramics1. The scheme of SPS is shown in Fig. 1. Sample is put in a graphite die in a vacuum chamber. It is pressed and pulse voltage is applied. The electric current heats the die. It is said that the pulse causes a spark-plasma between particles in the sample. Because of the spark- plasma, sample can be sintered at temperatures lower than that in the ordinary sintering by several hundred degrees of Celsius. The sintering period is also very short2Low sintering temperature and short sintering period in SPS technique cause low reaction rate. It is both disadvantage and advantage. In some cases, the reaction cannot be completed under the SPS conditions. If a mixture of several compositions having different properties can be sintered without a compositional change by the diffusion during the sintering, combination of properties, and therefore a design of property will be possible3. The low reaction rate of SPS may enable such combination."

Jan 1, 2000

By S. G. Kumar, R. G. Reddy

"Niobium aluminides offer the advantage of higher high temperature capability compared to other intermetallic aluminides due to the refractory nature of niobium. However, the reaction sequence in Nb-Al system is sluggish and currently there is a great interest in the processing aspects of these materials. In the present study, a systematic investigation was undertaken to compare the effect of different powder metallurgy processing routes on the phase relations and microstructure of 66Nb-22AH2Ti (in atom percent) alloy. The three different process routes adopted were: (i) cold pressing followed by reaction sintering; (ii) cold pressing and hot pressing followed by sintering; and (iii) arc melting, hydride-dehydride process to make the alloy powder followed by cold pressing and then sintering. The samples are analyzed by XRD, Optical Microscopy, SEM-EDS and EPMA. The analysis showed that alloy pellets made from pre-alloyed powders i.e., arc melting followed by hydride-dehydride process, gave good densification and more Nb3Al formation.1. IntroductionTo improve the performance standards of turbine engines, materials scientists are challenged to develop materials that have· high thrust-to-weight ratio with high specific strength, high specific modulus and good environmental properties at elevated temperatures. The conventional high temperature materials like nickel based superalloys are high in density and hence many of the high temperature materials scientists have focussed their attention on intermetallic aluminides like Fe-AI, Nb-AI, Ni-AI and Ti-AI in recent years. The phase relations and properties of alloys based on Fe-AI, Ni-AI and Ti-AI are fairly well known whereas little is known about the alloys based on niobium aluminides."

Jan 1, 1996

By Tanm Engin, Ali Riza Tarakcilar, Derya Dispinar

"Nowadays, the casting industry is developing parallel with the information technologies (IT). Particularly the casting simulation software is being frequently used in foundry floors for casting quality control and optimisation. In this study, the filling and solidification analysis of a rolling roll manufactured by spherical graphite cast iron were carried out by Vulcan casting simulation software. The appropriate defect relieving suggestions were presented by anticipation of defects that may form during the casting process.IntroductionThe optimisation of a casting process has long been the most focused area in manufacturing plants. Many of the work involve not only the process itself but the cost as well. When it comes to the process, it is important to be able to control the defects that may form during casting.The casting process begins with the melting of a charge; followed by pouring into the mould cavity. One of the most important factors is the difference in the liquid/solid density which may lead to porosity. On the other hand, turbulence during filling is another significant factor in casting operations [1].During solidification, due to the density difference between liquid and solid, porosity might form which leads to crack-like defects. There are several other factors that may determine the quality of a casting such as segregation, inclusions, grain size and etc. However, porosity is one of the first parameters that can be easily determine and controlled by the help of simulation software. Simulation is a cost-effective tool in the optimization of process parameters and castings can be visually observed. Time loss and economic expenses could be minimized [2]."

Jan 1, 2012

By Esperidiana A. B. Moura, Mariana N. Sartori, Vijaya K. Rangari, Angel Visentim Ortiz, Francisco R. V. Diaz, Rene R. Oliveira

"This work presents the preparation and characterization of a nanocomposite based on Poly(butylene terephthalate) PBT and Brazilian smectitic clay (bentonite chocolate clay). Before being incorporated as clay nanoparticles in PBT resin, the clay was organically modified by the addition of a quaternary salt and sodium carbonate. PBT/Clay nanocomposite (96.3:3.70 wt %) was obtained by using a twin-screw extruder machine. After extrusion process, the nanocomposite was characterized by tensile, flexural and impact tests, SEM, Vicat, HDT, DSC, TGA and XRD tests. The results showed that the properties of the nanocomposite obtained were superior to those of neat PBT. Concerning the temperature of thermal distortion (HDT) an expressive gain of around 45 % was presented to PBT/Clay nanocomposite compared to PBT evidencing the interaction of nanofiller with the polymeric matrix.IntroductionPolymer-clay nanocomposites, also called as polymer layered silicates nanocomposites have attracted much attention from both industry and academia over the past decade because they frequently exhibit unexpected properties. In contrast to the traditional fillers, nanofillers, in particular, nanoclay, is found to be effective. The addition of a small amount (< 5 wt.%) can show significant improvement in mechanical, thermal and barrier properties, flammability resistance, and electrical/electronic properties of the final polymer nanocomposite without requiring special processing techniques. Also, as with other nano-size particles, the overall crystallization rate and the glass transition temperature are also affected. It is generally believed that the improvement of properties of nanoclay composites is directly related to the complete exfoliation of silicate layers in the polymer matrix. However, a processing technique that produces complete exfoliation is still a technical challenge [1,2]."

Jan 1, 2012

By Ibrahim Yusufoglu, Ahmet Orkun Kalpakli, Cem Kahruman, Sedat Ilhan

"The effects of oxalic acid concentration, temperature, stirring rate and particle size on the dissolution rate of synthetically prepared calcium molybdate were investigated. Dissolution of calcium molybdate in oxalic acid solutions takes place as a series - parallel type reaction. In the first reaction step, which proceeds according to the ""Langmuir - Hinshelwood Mechanism"", calcium aqua oxalato molybdate is formed as a complex chelate intermediate product. In the second reaction step, molybdic acid is formed during the slow hydrolysis of calcium aqua oxalato molybdate, and it reacts rapidly with oxalic acid to form the polymeric hydrogen oxalate dimolybdate chelate as an end product. Activation energies were calculated as 41.4 and 49.9 kJ mol-1 for the first and zero order reactions. The fractional conversion versus time relationship can be given by the following equation.IntroductionMolybdenum is used widely in electric-electronic, metal working, aerospace and aeronautic, nuclear, glass and petrochemical industries because of its high melting temperature and resistance against chemical effects. However, the largest molybdenum consumers are the iron-steel and super alloy industries where molybdenum is used as an alloying element. Industrially important molybdenum minerals are limited to molybdenite (M0S2), powellite (CaMo04) and wulfenite (PbMo04), which are considered as primary molybdenum resources. Secondary molybdenum resources are spent catalysts and scrap [1-4].Molybdenum has been produced by pyrometallurgical processes in the past. Since it is possible to process low grade molybdenum ores and industrial wastes by hydrometallurgical processes, which are more environmentally friendly than pyrometallurgical processes, the importance of the use of hydrometallurgical processes has increased in the molybdenum production industry."

Jan 1, 2012

By Kinya Atsumi, Kanjana Khunathai, Hisaya Kato, Hidetka Kawakita, Keisuke Ohto, Katsutoshi Inoue

"Crosslinked microalgae were prepared from the residue generated in the production of biofuel, by crosslinking-condensation in concentrated sulfuric acid. These microalgae were tested for adsorption of various metal ions in hydrochloric acid medium. The crosslinked microalgae exhibited high selectivity for Au(III) over other precious and base metal ions. From an isotherm experiment, the maximum adsorption capacity was evaluated to be 3.25 mol/kg of dry gel for Au(III) which was many times higher than that of the original microalgae residue. SEM and X-ray diffraction confirmed the formation of metallic gold particles, suggesting the occurrence of a redox reaction between surface functional groups on the gel surface and trivalent gold ion.IntroductionSubstantial quantities of precious metals are being used by the electronic industry because of their excellent electrical conductivity and resistance to corrosion. In recent years, recovery of precious metals from secondary sources such as electronic scrap [1,2 ], and leach liquors is being favored because of environmental concerns. Of course, recovery is only practical, if its cost is lower than the value of the metals (gold, platinum and palladium) recovered.Traditional methods of separation and refining do not fulfill this requirement. In order to overcome this problem, attempts have been made in recent years to develop new processes including total leaching in hydrochloric acid containing chlorine gas or hypochlorite, followed by solvent extraction and ion exchange [3]. In the new processes, new solvent extraction reagents or ion exchange resins with high selectivity and high loading capacity are used to simplify the process and to reduce the operating costs."

Jan 1, 2011

By Carl A. Kuehn

At Carlin, Nevada, non-indigenous hydrocarbons were introduced as a bitumen phase which was mobilized due to burial under the Roberts Mountains allochthon. similarly, some indigenous organic matter was locally mobilized. Fluid inclusion and paragenetic data of veinlets formed during this hydrocarbon stage, combined with quantitative modelling or organic maturation, indicate that host rocks had evolved past dry gas conditions of around 1550 and l.l+0.2 Kb in the presence of CH4-saturated, highly saline brine by no later than early to middle Cretaceous time. All hydrocarbons present would have been rendered immobile under these catagenic conditions. Crosscutting relationships at several scales suggest that hydrocarbon mobility may have ceased prior to the intrusion of a series of dikes in the mine which have subsequently been altered and mineralized. Apart from subsequent oxidation, the current distribution and high maturity of carbon-rich zones were established prior to gold introduction. No Evidence has been found supporting proposed hydrocarbon "remobilization" during or after gold mineralization and alteration. The high density of the CH4-bearing fluid requires formation at high pressures (near 1 Kb) and precludes their formation as a result of the "cracking-off" of CH4 from organic matter during a thermal event associated with a shallow hydrothermal system. The density and composition of the fluid inclusions restricted to the early hydrocarbon-stages of the Carlin paragenesis are not unique to the sediment-hosted gold deposit environment of north-central Nevada. Similar inclusions are found in authigenic quartz crystals from Paleozoic carbonaceous shales in central Pennsylvania which have experienced normal metagenesis of indigenous organic matter due to deep burial.

Jan 1, 1987

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"In China, hazardous e-waste—cathode ray tube (CRT) glass is usually left around, and it is likely to contact with water resources directly. To identify the real leaching characteristics and bioavailabilities of heavy metals Pb and Ba contained in CRT glass in the nature environment, experiments were carried out by simulating the nature environment. The results indicated that Pb and Ba contained in CRT glass were stable in most conditions, which only showed obvious leaching toxicities in strong acidic/alkali conditions. EDTA and DTPA extractable Pb and Ba amounts were extremely high, e.g., EDTA extractable Pb of color funnel glass was up to 1960.07 ìg/kg, indicating that the potential bioavailability of waste CRT glass is very high. IntroductionIn recent years, cathode ray tube (CRT) contained monitors or TV sets has been substituted by novel and better electronic and electric equipments such as LCD and PDP, leaving huge amounts of end-of-life CRTs. 50~85% of the total weight of a computer monitor or a TV set is glass'1-21, which was classified to three categories: black & white glass (BW), color panel glass (CP) and color funnel glass (CF), according to their chemical compositions'3' (Méar et ai, 2006). In order to provide shielding from X-rays generated during the picture projection process, lead, barium and strontium oxides were used in the glass. In general, a color CRT contains 1.6-3.2 kg of lead'4'. Concerning the high toxicity of lead, these waste glasses have posed a potential risk to the environment and human health and researches on these glasses have been attracting wide and tense attention currently."

Jan 1, 2011

By Ken-ichi Miyazawa

A Center of Excellence (COE) titled the Creation of Nature-Guided Materials Processing, called Nature COE, has been established at Nagoya University. In the Nature COE, a new field of material research is being developed through learning the laws of nature, namely, methods of attaining ?appearance of the maximum function under the minimum substance and energy consumption?, which the nature and living organisms have acquired through their evolution in long period. As one of the specific features, an ?Open Cluster Program? was originated for promoting the researches conducted by young researchers and Ph.D. students with those in and out of the university and also for fostering them, together with such educational programs for Ph.D. students as the research incentive, the oversea training and the international lodging seminar programs. The Open Cluster Program has been found to be effective for fostering of young researchers and students, for promoting their researches, for gathering researchers and knowledge from the world and for propagating the research fruits. Through conducting these programs, world-highest intelligent fruits and a gathering of young minds to lead the new field are expected. In this COE, the researches are conducted on (1) materials used for living bodies, (2) mimicking structures which nature or living bodies are forming and (3) materials processing by mimicking processes to form the structures observed in the nature or the living bodies. These researches are conducted by four groups to extend the processes observed in the natural world to a new type of processing that is thoroughly rationalized by plunging a scalpel of engineering, and to establish a new academic field of materials science and engineering.

Jan 1, 2006

By Leah Penner, Thomas J. Ruth, Paul Schaffer, François Benard, Edouard Asselin, Stefan K. Zeisler, Thomas J. Morley

"This paper details the electrodeposition of metallic molybdenum from an aqueous, acetateelectrolyte containing molybdate ions. The deposition is carried out in a highly concentrated (up to I 0 M) acetate bath in the presence of a very low concentration of bone glue (60 µg/L). The molybdenum metal deposits are up to 20 µm thick and adherent. The deposits were characterized by XRD and XPS analysis. The deposition process is very inefficient, as up to 99% of the current is used to generate hydrogen during electrolysis. The effect of acetate concentration, pH, additives and current on the deposition efficiency and physical properties of the molybdenum deposit were investigated and optimized to obtain smooth, adherent coatings.IntroductionMolybdenum has increased thermal and wear resistance properties that are often utilized in material coatings [I]. These coatings are most often manufactured by sintering, pressing or spraying molybdenum powder at elevated temperatures, as a substitute method for standard metallurgical practices, such as electroplating [2, 3]. The lack of reports describing molybdenum deposition is most likely due to the highly oxophilic nature of molybdenum and the stability of its oxides, especially in water. Previous attempts to electrochemically reduce molybdenum from molybdate (Mool·) ions to molybdenum metal have reported the production of either a poorly adherent mixed oxide [4-6], or a thin(< 0.1 µm) metallic film [7-9]. Thick metallic molybdenum is capable of being co-deposited with one of the iron-group metals (Ni [10], Co [11] and Fe [12]) to produce an alloy [13, 14]. These alloys, however, may not be suitable for applications requiring pure molybdenum as they usually contain less than 50% molybdenum (often less than 30%)."

Jan 1, 2012

By M. -V. Wang

Hydrotreating and hydrorefining (HT and HDS) spent catalysts contain molybdenum, vanadium, nickel or cobalt at concentration levels that can make metals recovery economically viable. Quanzhou Jing-Tai of China has developed, through many years of operating experience in metal recovery from spent catalysts, a simple process for recovery of these metals and the production of environmentally benign residues. The process first subjects the catalysts to a low-temperature calcination step, followed by grinding of the calcine. The ground material is then leached with 10-20% v/v hydrogen peroxide to recover metals such as Mo, V and Ni or Co. This step has a selectivity that is greater than 95% for the metals. The undissovled residue, which contains mainly Ah03 and Si02, can be dewaterd and used in the production of masonry bricks. The pH of the rich liquor is then adjusted to between 0.5 and 2.5 by adding dilute sulfuric acid to co-precipitate Mo and V, with a recovery rate of greater than 99%. The lean liquor contains mostly dissolved Ni or Co, which can be recovered through precipitation at a pH of between 8.5 and 9.5 by caustic additions. The final liquor is then sent to an ion exchange step for final recovery and cleanup of residual metals. The effluent is then discharged after a simple wastewater treatment process, which has been found to meet all environmental requirements. The entire process has been found to be simple, cost-effective with minimal environmental impacts while achieving the goal of complete resource recovery from spent catalysts commercially.

Jan 1, 2000

By M. Sripathy, K. V. Sharmal

"The conventional fiber reinforced plastic does not participate in the plastic deformation or enter the large plastic deformation state during collision. On the other hand, sandwich structure allows more plastic deformation, which improves the energy absorption efficiency. The objective of this study is focused on the investigation of the crushing of sandwich structure made from sisal / coir / bamboo/ glass fabrics as reinforcement and with polyester resin to form the composites skin and with polyurethane foam as the core. Experiments were conducted, showing that the underlying crushing mechanism of sandwich structures is very different from that of solid-section thin-walled structures. When a sandwich is subjected to crushing, the core deforms in the shear mode and the face bends independently. The damage is through the width zone of crushed foam core accompanied by a residual crushing in the foam. It is shown that such damage causes a significant reduction of compressive strength. Results show that glass/polyester and bamboo/polyester skin based sandwich structures have superior compressive strength. Coir /polyester based sandwich structure come next to glass/polyester sandwich structures in this aspect which is then followed by Sisal /polyester based sandwich structures.IntroductionCellular polymeric foam sandwich structures are often employed in shock mitigating applications. The cellular polymeric foam has several favorable properties, such as, low density, relatively high strength-to weight ratio and a significant degree of crushability. This high crushability is the result of the large void ratio in such materials, which also facilitates the collapse of cell walls via bending and buckling [1]. A few feasibility studies on FRP sandwich panels show that the panels efficiently provided high mechanical performance for minimum weight [2]."

Jan 1, 2012