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By Felipe Perissé Duarte Lopes

The tensile properties of DGEBA/TETA epoxy matrix composites reinforced with different amounts of curaua fibers were evaluated. Tensile specimens with up to 35% in volume of long, continuous and aligned curaua fibers were room temperature tested in an Instron machine. The fracture was analyzed by SEM. The results showed significant changes in the mechanical properties with the amount of curaua fibers. This was compared to other bend-tested composites with distinct matrices. The fracture analysis revealed a weak fiber/matrix interface, which could be responsible for the comparatively low performance of some properties.

Jan 1, 2010

By Burcu Ertug, Necip Ünlü

"On average, one out of two glass bottles coming on to the market is provided by recycling processes in Europe. Glass recycling has been started by the early of 1970s in Turkey, and the recycling amount has been reached to 70 thousand tons recently, while 4.2 million tons which represents only 25 percent of total glass manufactured, is the amount of glass collected annually for recycling in the world. The glass recycle process basically involves collecting, sorting, then crushing and grinding after which glass cullet is produced as the secondary raw material. Removing of the contaminants from the glass cullet, and then melting are the next steps. In this study, recent developments of 100% recyclable without any deterioration in quality, and never decomposable glass, are discussed detailed in terms of glass production processes.1.IntroductionIn many countries, waste glass constitutes a large proportion of solid wastes, and recycling the glass is a major environmental problem all over the world [1]. Among the diverse types of waste, glass is one of the most valuable recycling materials because it can be revived and recycled completely and hardly decomposes [2]. Between 80% and 85% of the mass output from the worldwide glass industry is either in the form of containers for the food, beverage, and pharmaceutical industries, or flat glass for building construction or for motor vehicle manufacture. Other product segments, whilst only constituting about 15% of the mass output, produce high value technical and consumer products by comparison with container and flat glass [3].In the present study, the recycling of Liquid Crystal Display (LCD), Cathode Ray Tubes (CRT) and Printed Circuit Boards (PCB) were examined. The production of glasses and glass-ceramics from glass cullet, synthesis of different compounds from recycled glass were other subjects of interest. The use of recycled glass for construction industry and using glass as aggregate were emphasized. Finally the recovery of glass fibers were investigated."

Jan 1, 2012

By Qingsheng Liu

A new method of recycling aluminum dross for preparation Al-Si-Ti alloy was studied in this paper. This was carried out in two processes. first the aluminum doss was pretreated by leaching and calcining process, the fine purity and phase of the intermediate oxide powder up to electrolysis demands, then, could be obtained when aluminum dross after washing have been leached for 2h at 100? in 20% hydrochloric acid and calcined for 2h at 1200?, which was treated by cryoite-based molten salt electrolysis. Finally, the Al-Si-Ti alloy was successfully obtained through electrochemical co-deposition in the cathode shows a typical as-cast microstructure. This new recycling method can produce high quality alloy and may bring remarkable economic and social benefits.

Jan 1, 2010

By Zhuokun Cao

Manufacture of aluminum foams still suffer from nonuniformity and poor reproductively for there is lack of basic knowledge of foaming process. In this paper, carbon fibers are used as novel stabilizing additive for aluminum foams, and the structure evolution of aluminum foams with different fiber content was studied. A laser rangefinder was used to detect the expansion rate of different al foams. Al foam samples are solidified at different foaming time to determine its relative density and cell size distribution. Results indicate that the cell size of foams linearly increases with the decrease of density, and the slope of the line is influenced by fiber content. The relationship between expansion ratio, density and cell size of the foams is discussed. It is concluded that the density of resulting foam is influenced by the rate of gravity driven drainage, and its cell size is determined by expansion ratio and foaming time.

Jan 1, 2010

By S. B. Johnson

Keywords: Spray, Aluminum, Simulation A stochastic, droplet-resolved model has been developed to describe the behavior of a binary aluminum alloy spray during the spray-rolling process. In this process, a molten aluminum alloy is atomized and the resulting spray is deposited on the rolls of a twin-roll caster to produce aluminum strip. The one-way coupled spray model allows the prediction of spray characteristics such as enthalpy and solid fraction, and their distribution between the nozzle and the deposition surface. This paper outlines the model development and compares the predicted spray dynamics to PDI measurements performed in a controlled configuration. Predicted and measured droplet velocity and size distributions are presented for two points along the spray centerline along with predicted spray averaged specific enthalpy and solid fraction curves.

Jan 1, 2005

In this study, the method of chemical co-precipitation?reduction?diffusion was developed for the preparation of magnetic SmCo5 alloy. In the chemical co-precipitation process, the effects of solution pH, the reactant concentration, the dispersant on the process were investigated. The optimum conditions of the process were determined, and the SmCo5 alloy oxide precursor particles with fine crystalline structure, narrow size distribution was obtained. Then, by reduction-diffusion treatment of the precursor particles, the SmCo5 alloy with high quality was produced. It is anticipated that the co-precipitation-reduction-diffusion is a novel method available for SmCo5 alloy production.

Jan 1, 2006

By Pinakin C. Chaubal

An industry ? university consortium was set up to develop advanced tools necessary to understanding of the various phenomena occurring in the hearth of the modern iron making blast furnace. The major driver for this work was to provide the technological support required to extend campaign life of blast furnaces, which, by current agreement is tied to the life of the furnace hearth. The hearth wear is significantly affected by the hot metal velocity, temperature distribution and refractory temperatures. Due to the difficulty in making measurements inside the hearth, novel approaches to gain a fundamental understanding of the detailed physical and chemical processes in the hearth must be developed. The approach used in this project was to develop a 3-D CFD (Computational Fluid Dynamics) model coupled with extensive validation efforts. The CFD model is being utilized (1) to understand the phenomena in the hearth, (2) to understand the impact of changes in the internal conditions of the hearth on wear patterns; and (3) to design a monitoring/controlling system for prolonging campaign. In this paper, the results will be reviewed.

Jan 1, 2006

By Hani Henein

Recent innovations in atomization of molten metals have occurred in the area of single fluid atomization. Impulse Atomization (IA), one of the single fluid techniques, provides unique capabilities to study different regimes of atomization in a controlled environment. By changing processing variables, a mono-dispersed distribution of droplets above one millimeter in diameter can be produced. This is accomplished through proper characterization of the forces influencing the process and in particular the flow of melt through the orifice. This paper will discuss the approach and illustrate results with molten aluminum and cobalt.

Jan 1, 2006

By Neil E. Ryan

Because of their chemical reactivity and affinity for oxygen, rare-earth elements are difficult to extract, and due to their close chemical similarity, it is an exacting task to separate one from the other. Nevertheless, these same characteristics can be used to benefit other metals by enhancing their resistance to high-temperture oxidation/corrosion and by inhibiting their corrosion in aqueous environments. This paper gives an overview of the use of rare-earths: [a] as alloy additions, [b] in coatings, and [c] when added to hostile environments, to retard rates of high- temperature oxidation and inhibit aqueous corrosion.

Jan 1, 1992

By P. K. Narasimharaghavan

The major threat to the sustainability of Aluminium Industry is its significant contribution to global warming by way of generation of non eco-friendly gases during its production cycle from Bauxite to the finished product. Though reduction measures are taken in control and effective recovery of values from pot room gases, efforts in use of environment friendly additives in the final products production line is warranted. In this line, the present paper describes our efforts in the use of a new generation refining flux which apart from helping in effective removal of alkali metals, reduction in inclusions and ensure a better metal cleanliness shall also aide in reduction of obnoxious gases generated during the metal refining process prior to casting. The aim of the current work was to reconcile the practical results with the old generation fluxes used. Further improvements to bring in a better metal cleanliness will also be discussed.

Jan 1, 2010

By Orhan Gokce Goksu

It has been shown that metallic tungsten powder can be obtained by electrochemical reduction of solid CaWO4 in molten CaCl2-NaCl eutectic mixture at 600oC. In this study, constant and pulse voltage electrolysis experiments were performed to optimize reduction kinetics and obtain information about the mechanism of above process. It was found that pulse voltage applications yield faster reduction rates when average voltage of pulse voltage application was the same as constant voltage application. In addition, analysis of the current vs. time graphs of constant and pulse voltage electrolysis studies showed that reduction occurs at potential differences higher than about 2.2 V between CaWO4 cathode and graphite rod anode.

Jan 1, 2010

By Sutham Niyomwas

Silicon-Silicon Carbide (Si-SiC) composites were synthesized by self-propagating high temperature synthesis (SHS) from a powder mixture of SiO2-C-Mg. The reaction was carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The effects of silica sources and carbon mole ratio in precursor mixture on the Si-SiC conversion were investigated using X-ray diffraction and scanning electron microscope technique. The as-synthesized products of Si-SiC-MgO powders were leached with 0.1M HCl acid solution to obtain the Si-SiC composite powders.

Jan 1, 2009

By Jilai Xue

Oxygen gas bubbles generate on anode during Pb electro-deposition process in PbSiF6-H2SiF6 aqueous solutions at room temperature. Cell voltage varies as the bubbles formed on the anodes surface. The bubble layer on the anode makes a voltage drop that consumes energy in the Pb process, which can be reduced by applying ultrasound on the anode. The effects of ultrasound frequency and anodic current density were investigated with ultrasound on and off, alternatively during the Pb electrode-position process. The removing of the gas bubbles were recorded in association with a drop in the cell voltage. The cell voltage can be lowered by 4% - 6% with ultrasound, which has potential for energy saving in Pb production.

Jan 1, 2010

By Ram Avtar

High tensile thick plates (>80mm, weight ~3000 Kg) of medium carbon low alloy steel, when heat treated, manifested higher percentage of crystalline area (>20%) in fractured surface. Such problem was not encountered in thinner plates. The genesis of higher crystallinity in fracture was examined. It was observed that the thicker plate undergone slower rate (Average 0.9oC/Sec.) from soaking temperature to Ms temperature) of cooling after austenising during oil quenching and thereby quenched microstructure had upper bainites. During tempering of as quenched bainite, additional precipitation took place at the lath boundaries of bainite. This led to weakening of grain boundaries and aided easy crack propagation during fracture and resulted in formation of higher percentage of crystalline area in fractured surface. Enhancement in cooling rate (Average 1.8oC/Sec. from soaking temperature to Ms temperature) of austenised plate by switching over from oil quenching to water quenching practice resulted in complete transformation of austenite into martensite and produced ductile fracture (zero Crystallinity). Plates conformed improvement in mechanical properties between 2-5%.

Jan 1, 2009

By Leon H. Bruner

This paper presents a case study describing how a global consumer products company with 138,000 employees that markets over 300 brands in 180 countries is building sustainability into the rhythm of its business. This strategy extends beyond social investment programs by incorporating sustainability into the fabric of product design, manufacturing operations, employee engagement and stakeholder partnerships. During the implementation of this program it has been necessary to be explicit about sustainability and its importance to the business, to broadly define sustainability, to ensure that sustainability is not added work, to eliminate trade-offs between performance, value and sustainability and to implement programs to ensure that sustainability is incorporated into the DNA of the company. Our program continually emphasizes the importance of making no tradeoffs between consumer acceptance of sustainable products and sustainability investments. We also work diligently to overcome the challenges of engaging employees around the world to implement a single coherent sustainability strategy that delivers great results.

Jan 1, 2010

By Godwin Beene

During recent years, copper and acid production from Nkana Smelter has formed a significant proportion of ZCCM's total output, but a number of problems affecting the smelter over the last decade have only been recently overcome. This paper discusses recent developments in the smelting practice, highlighting some of the operational problems experienced and associated solutions. The smelter performance over the decade is discussed and the innovations in the smelting technology employed to sustain production in the wake of limited re-capitalization are dealt with in detail.

Jan 1, 1999

By Raj P. Singh Gaur

Due to high concentration of NaOH in the digested slurry after scheelite digestion, it is diluted to about 4N before filtration to separate sodium tungstate solution from the sludge (residue). However, in practice there may be deviations in the normality of NaOH present in the slurry. There may also be variations in the temperature of the slurry and filtration time. Slight variations in these parameters could cause tungsten losses in the sludge via the back reaction: Ca(OH)2 + Na2WO4? CaWO4 + 2NaOH This paper pertains to the effect of normality, temperature and time on the tungsten losses in the sludge that is separated from ?diluted-scheelite-slurry-in-NaOH? via filtration. Results indicated that tungsten losses in the filtered residue (sludge) were quite significant when the slurry temperature was kept at 70°C or higher. The effect of high temperature was less significant at the slurry normality of 3.6 or higher. Combination of low slurry normality (<3.6) and high temperature (>60°C) resulted into large W-losses in the sludge.

Jan 1, 2006

By Jewel Andrew Gomes

Arsenic is considered as one of the toxic materials being controlled by Environmental Protection Agencies in several developed and developing countries. It is found in the nature as constituents of the soil, minerals and also in various organic forms. It enters the air, water, and land from wind-blown dust and gets into water from runoff, leaching, soil erosion and anthropogenically from chemicals used for wood preservation, insecticides, medicine, military purpose, pigments, and electronic circuitries. There are several techniques available for removal of Arsenic, such as coagulation/filtration, lime softening, ion exchange, reverse osmosis, nanofiltration, wet chemical, and electrochemical. Electrocoagulation has been found as one of the most efficient techniques to remove inorganic arsenic with more than 99% efficiency. In this paper, we present our work on electrochemical treatment of both the inorganic and organic arsenic from water using various sacrificial electrode materials, i.e., iron, aluminum, copper, and combination of them. The floc produced by this method has been also characterized using XRD, SEM/EDS, FTIR, and cyclic voltammetry.

Jan 1, 2010

By Pietro Navarra

A great deal of effort has been expended on how to optimize conventional water cooling circuits in furnace cooling elements, and the results have been largely satisfactory. However, there is a general agreement that the proximity of high-pressure water passages to the flow of molten furnace products is a safety concern. Nonetheless there exists little alternative to the formula: increasing furnace integrity implies the incorporation of more extensive forced-convection water cooling systems. Recent developments in evaporative cooling technology have resulted in the development of a high-capacity heat pipe capable of operating under the thermally intense environments of a metallurgical furnace. The system functions using several kg of a working fluid (water) in total, has no moving parts, and allows for a significant reduction in cooling water requirements. Full-scale pilot tests of a copper tap hole and slag launder were done in 2003 and2005, with detailed results given in this paper.

Jan 1, 2006

By Linda Gaines

Use of vehicles with electric drive, which could reduce our oil dependence, will depend on lithium-ion batteries. But is there enough lithium? Will we need to import it from a new cartel? Are there other materials with supply constraints? We project the maximum demand for lithium and other materials if electric-drive vehicles expanded their market share rapidly, estimating material demand per vehicle for four battery chemistries. Total demand for the United States is based on market shares from an Argonne scenario that reflects high demand for electric-drive vehicles, and total demand for the rest of the world is based on a similar International Energy Agency scenario. Total material demand is then compared to estimates of production and reserves, and the quantity that could be recovered by recycling, to evaluate the adequacy of supply. We also identify producing countries to examine potential dependencies on unstable regions or future cartels.

Jan 1, 2010