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By A. R. Kiani-Rashid

Controlled graphitization has become known as a practical method for improvement of wear resistance and machining properties in steels. In this paper, the effect of heat treatment on microstructure of CK45 steel has been investigated. Austenitising was carried out at 920°C for 5 hours. Besides, isothermal transformation was conducted at 750°C in the time range of 1-20 hours. The microstructure of the steel considerably changes by this heat treatment process which exhibits the effects of temperature, appropriate austenitising duration and isothermal transformation. Conducted experiments show a suitable distribution of semi-spherical graphite particles especially on the surface of the steel. Also, analyses demonstrate that the amount of formed graphite in the austenitising temperature 920°C is more than graphite in single heat treatment temperature of 750°C.

Jan 1, 2010

By P. N. Anyalebechi

The effects of a cross-hatched grooved mold surface topography, casting speed, and superheat on the morphology of solidifying shells of aluminum alloy 3003 have been characterized by a series of immersion tests. The cross-hatched grooves were 0.232 mm deep with wavelength or spacing between 1 mm and 15 mm. The shells solidified at casting speed of less than 10 mm/s on the 1 mm spaced cross-hatched grooved mold surface were fairly uniform with little or no localized variations in thickness. However, the propensity for non-uniform shell growth morphology was exacerbated by an increase in casting speed, melt superheat, and the wavelength of the cross-hatched grooves. This is provisionally attributed to their effects on interfacial heat transfer and wetting of the mold surface by the molten metal.

Jan 1, 2008

By P. F. Kerr

This is not a conventional professional paper. It deals mostly with personal experiences. These concern a background in applied mineralogy. Your committee asked me to do this. I accepted with a California enthusiasm which has since diminished with the approach of a Chicago winter. Nevertheless, I wish to thank your committee and also to apologize in advance for omissions and inadequate statements, as such a paper must possess. My introduction to applied mineralogy took place in 1922 at Stanford University. Physicists had recently demonstrated that crystalline powders would reflect x-rays in a systematic manner. Professor A.F. Rogers sug¬gested that significant x-ray reflections might be obtained from powdered opaque minerals. With the aid of Professor D.L. Webster in the Physics Department, I constructed an x-ray diffraction outfit. It was a crude affair, but it worked. Starting with 1924, we secured recognizable patterns of a goodly number of ore minerals (1,2,3). Today x-ray diffraction outfits are common, and a card system of mineral identification is constantly used.

Jan 1, 1981

By Marilia S. de Magalhaes

Keywords: sinter, characterization, agglomeration, iron ore Iron ore sinters are the main burden of blast furnaces for pig iron production. The evaluation of these agglomerates is very important due to their properties affect indirectly the productivity and costs of production of the steel industry. In the sintering plants, the standard procedure of sinter assessment has been carried out by particle size control, bulk chemical analyses, tumbler and/or shatter tests and determination of reduction degradation and reducibility indexes. Microscopy techniques have just been applied to characterize sinters produced in pilot conditions, however, these techniques, the classical ones and the less traditional, allow enhancing the industrial sintering process assessment. For investigation of the phases, microstructures and fabric, reflected-light and scanning electron microscopy(backscattered electrons images) were used; for micro analytical chemical examination, energy-dispersive X-ray spectrometry; for Kikuchi patterns registers, electron backscattering diffraction. In addition to the microscopy techniques, the magnetic behavior was depicted by means of magnetic susceptibility measurements. Iron ore sinters are made up by hematite, magnetite, silicoferrite of calcium and aluminium and silicates. These phases develop either during sintering or, in some proportion, represent remnants of ores and fluxes; this is the case of some hematite and Mg-bearing silicate, respectively. From the magnetic susceptibility results, three different behaviors were determined, which are directly related to the magnetiteproportion in the samples. The phase association and proportion, the sintering conditions andthe quality assessment are some features appraised by such procedures, which reveal themagnitude of this proposal in sintering plants.

Jan 1, 2005

By Valerio Viti

In High Pressure Die Casting a molten metal is injected through a thin gate into the cast cavity. High injection pressures and high gate velocities create atomization phenomena which can negatively affect the final quality of the cast. In order to control atomization process it is essential to understand the atomization patterns and the two-phase flowfield that exist at the gate exit. In the present work, 2D numerical simulations of the flow of molten Magnesium through a high aspect-ratio rectangular gate are performed using a water analogue for an open and closed cavity. The numerical simulations made use of VOF-type (Eulerian) physical models and Lagrangian models. Further, a sub-grid scale model was implemented that, in conjunction with VOF-type equations can efficiently predict the general atomization pattern without the need for high-resolution grids. The numerical results were compared to experimental data for validation.

Jan 1, 2006

By Lijuan Chen

During the detoxification of chromium-containing slag by Achromobacter sp. CH-1, anionic surfactant Sodium Dodecyl Sulphate(SDS) and its mixed systems with different Tween surfactants(Tween 20, Tween 60 and Tween 80) were used to promote the interaction between the bacteria and the chromiumcontaining slag and the rate of acid-soluble Cr( ? ) leached from the slag. The effects were evaluated by the surface tension, the pH of the leaching solution and the leaching rate of total Cr( ? ) from the slag. The results showed that the surfactants systems improved Cr(VI) leaching and its detoxification of chromium-containing slag. The mixed surfactants of SDS combined with Tween surfactant revealed better effectiveness of detoxification than SDS only. When the mass ratio of SDS to Tween 80 was 1:1, the rate of Cr( ? ) leached from the slag increased by 12%.

Jan 1, 2009

By Jewel A. G. Gomes

Green rust (GR) are layered Fe(II)-Fe(III) double hydroxides, having a pyroaurite-type structure consisting of positively charged hydroxide layers and hydrated ions in interlayers. This special feature of GR is very efficient for wastewater treatment as the pollutants are easily taken in or exchanged with the anions in the interlayers. It can be simply and cost-effectively produced by electrocoagulation (EC). Chicken processing plant (CPP) produces large amount of wastewater containing variety of readily biodegradable organic compounds, fats, and proteins. The possible re-use of properly treated CPP wastewater would be economic and environment friendly. In this study, we present our work on treatment of CPP wastewater using EC, specifically for the removal of COD. Analysis of the EC-treated water for reuse in the same plant is discussed considering the U.S.EPA regulations. Two types of EC-reactors were used for this purpose. To better understand the treatment mechanism, EC-floc was also characterized using XRD and SEM-EDS.

Jan 1, 2010

By Changqing Su

A batch incubation experiment has been carried out to investigate the optimal condition for the microbial remediation of hexavalent chromium (Cr(VI)) in soils contaminated by chromate ore processing residue at Hunan Iron-Alloy Factory in China. The optimal condition was obtained by comparing the remediation efficiency of Cr (VI) by indigenous bacteria under different culture media, the quantity of nutrient sources, the pH and the temperature. The results indicated that glucose and yeast extract was the optimal component of culture medium and the quantities of the above components were 8 g L-1 and 13 g L-1, respectively. The optimal temperature and pH value were 30_ and 10.0, respectively. A bioreactor was operated under the optimal condition to evaluate the efficiency of Cr(VI) remediation in the contaminated soil. The result showed that water soluble Cr(VI) in soils was reduced from 320 mg kg-1 Cr(VI) of the initial concentration to below detection limit after 30 h in a bioreactor. Thus, there is a large potential to make bioremediation for the reduction of Cr(VI) to Cr(III) by the addition of optimal culture medium under aerobic condition.

Jan 1, 2010

By Tian Sugui

By means of the measurement of the enduring property and microstructure observation, an investigation has been made into the influences of the element Re and TCP phase on the enduring property of the single crystal nickel base superalloys. Results show that the needle-like TCP phase is precipitated along the <110> orientation on {111} planes in Re-containing/free superalloys during the long term aging, the TCP phase is identified as µ phase, and the precipitated µ phase in 4.5%Re alloy is gradually spheroidized during aging. Thereinto, the needle-like µ phase may obviously decrease the enduring lifetimes of the alloys due to the consumption of the refractory elements and the effect of the stress concentration. But the stress concentration is not easily generated in the regions near the spherical-like µ phase, which is a main reason of reducing the enduring lifetime of 4.5%Re alloy to a small extent.

Jan 1, 2010

By Ulises Crossa Archiopoli

We describe a technique that allows rapid imaging of the thermal diffusivity of the sample by a modified photo-thermal technique. The thermal diffusivity in hardened steels strongly correlates to the hardness. Hence in a noncontact manner and with optical microscope resolution, a 2D map exhibiting the crystallographic phases and hardness of the sample can be retrieved. Two almost collinear laser beams scan the surface, one as a modulated pump and a second as a CW probe. The deflection of the probe carries information on the thermal expansion of the sample and with it, on the thermal diffusivity. It is shown that a single determination of the time delay of the modulation of the probe beam can be used to retrieve the thermal diffusivity.

Jan 1, 2010

By Clara María Lamus Molina

The following minerals found in the residual black sands from gold mining in El Bagre Antioquia (Colombia) were identified as having major economic interest: Ilmenite (FeTiO3), with an average of 49% of TiO2, frequently altered presenting crowns; lamellaes of rutile and alteration textures; titanomagnetite with up to 25% of TiO2; magnetite (Fe3O4) in individual grains or associated with others minerals as hematite and ferromagnesian silicates rutile (TiO2) with considerable quantities of Nb2O5(0.1-3.7%Wt); zircon (ZrSiO4) with 66%Wt of ZrO2 and monazite with an average of 63.43%Wt of REE, this frequently associated to xenotime and thorite forming textures as little drops. Analysis in EPMA and SEM/EDS showed percentages of minor elements and traces, thereby clearly establishing the applications of these minerals in diverse industries. Furthermore, a detailed granumetric study of the different minerals and textural relationships among them also allowed for establishing the basis for possible processing and exploitation.

Jan 1, 2006

By Art Cooper

Granulation systems are customarily viewed as problem areas in metallurgical operations. The inherent risk of explosion when combining a high temperature melt with water creates a safety hazard. Separation of the granulated material from the quenching medium generally involves equipment that can have significant maintenance and operating costs. Granulation systems&apos; reliability and availability can negatively affect the plant production. Against this background, granulation systems have been treated by design firms and producers as an add-on and a necessary evil. The technology is becoming better understood and solutions to common problems are being found. This paper will discuss typical problems in common systems, and some of the improvements that have been made, with particular reference to non-ferrous applications.

Jan 1, 2006

By Z. Sun

Imposing a strong magnetic field is considered to be an attractive method to prepare materials with aligned or textured structures due to its intrinsic properties, e.g. non-contact and easily controllable. However, the nature of the strong magnetic field effect still remains unclear and further research is needed. In the present paper, the effect of a strong magnetic field on the solidification of a hypereutectic Al-Cu alloy was investigated. After magnetic field treatment, the primary phase was aligned parallel to the magnetic field direction. Meanwhile, the eutectic micro-structural constituent became elongated and thinner. A theoretical analysis was conducted to have a better understanding of the phenomena. During solidification, the magnetic Faraday and dipole-dipole interaction forces are considered to decrease the solute pile-up in front of the solid-liquid interface and modify the eutectic cell formation. The alignment of the phase is due to the shape magnetic anisotropy and crystal magnetic anisotropy.

Jan 1, 2010

By Yue-yuan Li

China has abundant magnesite resource, but the low-grade and powder ores have always been rejected, which influences the comprehensive utilization of resource and often causes circumstance problems. The present work investigated the preparation of magnesia whisker using magnesite tailings as starting materials by preparation magnesium carbonate whisker as precursor firstly in the route of calcination, hydration, carbonation and pyrolysis, follows by second calcination of the precursor. The influence of pyrolysis conditions and additives on morphology of magnesium carbonate crystal as well as the influence of calcination conditions on morphology of magnesia whisker was investigated. The results showed that thermal decomposition products was MgCO3?3H2O. Magnesium carbonate whisker with length of 10~60 µm and the length-to-diameter ratio of 10~20 was prepared when soluble magnesium salt was added. While temperature was elevated at 1°C?min-1, magnesia whisker with length of 10~60µm was obtained.

Jan 1, 2010

By Zhiyun Li

Room temperature infrared reflection spectra of 2 n-type homo-epitaxial epifilms have been measured in the work. The effect of the refractive index on the determination of layer thickness using traditional calculation measurement is studied and some improvements have been added to the measurement to improve the accuracy and stability of the measured results. Results of the improved method have great agreement with the results from SEM and both variance and mean relative error decrease an order of magnitude.

Jan 1, 2010

By W. K. Connor, O&apos

Thermal Treatment Technology Division Albany Research Center, U.S. Dept. of Energy Oregon. This evaluation included a characterization study and direct smelting tests conducted in a bench-scale electric arc furnace (EAF). In contrast to other thermal treatment technologies considered for these wastes (i.e., fluidized bed combustion), direct smelting in the EAF can process 100% of the wastes without prior beneficiation, and utilizes solid oxidant additions (in this case iron ore) rather than air to oxidize the carbon. This solid oxidant addition is advantageous because it results in the production of several value-added furnace products. These products include cast iron resulting from the reduction of the iron oxides, baghouse dust containing virtually all of the zinc from the residues, and a clean (nonhazardous) slag product suitable for recycle as concrete aggregate or construction fill. Offgas from the smelting furnace also holds potential as fuel gas for cogeneration. The direct smelting tests conducted thus far were successful at producing the desired furnace products, exhibiting the potential for complete recycle of the waste pile. A cast iron product of comparable quality to conventional cast irons was produced, at nearly 80% iron recovery to the metal. The slag product was determined to be nonhazardous, based on the EPA TCLP. Lead and zinc partitioning to the dust product was greater than 99%. The material balance over the furnace indicates that for every ton of feed processed, 540 lb. of cast iron, 600 lb. of slag, and 150 lb. of dust would be produced. Energy consumption was roughly 1.10 kWxh/lb of feed material. Prior experience suggests that these figures measured in the bench-scale furnace would translate to 0040 to 0.50 kWxh/lb at the industrial-scale.

Jan 1, 2000

By Jian Li

Developing the Generation IV nuclear reactor is an international collaborative effort. One of the most promising Gen IV nuclear reactor designs is the supercritical water (SCW) concept, in which the water coolant runs at about 625 oC at the outlet. Under this temperature and high pressure condition, the cooling water is at supercritical state, which poses significant demand for both in-core and out of core materials. High-temperature mechanical properties, corrosion resistance and radiation damage are some of the key challenges. At present, no single commercial material can meet all the requirements of the severe SCWR conditions. Corrosion experiments per-formed under SCW condition yield various kind of corrosion modes, some are very challenging to characterize using conventional techniques. A combination of various advanced characterization techniques proofed to be essential to understand the root cause of materials? degradation.

Jan 1, 2010

By Petr Stehlík

"This paper is aimed at showing and demonstrating progress in technologies and improvements in units for the thermal processing of various types of waste. The following areas are covered: units for the thermal treatment of hazardous industrial waste and common MSW, technologies for the thermal treatment of industrial and sewage sludge, utilizing waste in cement production (material and energy recovery), up-to-date off-gas cleaning systems, original and unique units for the thermal processing of polluted gases, low-NOx burners. The paper represents a review based on industrial applications, papers published in reputable international journals and a monograph under preparation.IntroductionThe present contribution is an overview of the activities and achievements of the Institute of process and environmental engineering (UPEI) of the Brno University of Technology (VUT). The Institute belongs to European leading teams in the field of the thermal processing of various types of waste. The research in the institute currently revolves mainly around a strategic project “Waste and Biomass Utilization focused on Environment Protection and Energy Generation” that is supported by the national government. Due to the limited space this paper is conceived as a review of papers published especially in reputable international journals.Main (strategic) target of the research is development of new, efficient processes (eventually modernized processes with novel original elements) for effective and highly efficient treatment of waste and biomass, including their maximum utilization as renewable energy sources while minimizing harmful emissions. To this purpose, highly advanced know-how for the design and construction of the related technology lines is being developed, supported by mathematical modeling (see e.g. [1]), experimental validation and optimization.Municipal and Industrial Solid Waste – Concept of Waste-to-Energy CentersThermal processing of various types of wastes is not only waste disposal and/or treatment at present. It has to be regarded as waste to energy process wherever and whenever possible and feasible. This observation was at the origin of the concept of new regional Waste-to-Energy Centers (WTEC), outlined in the following paragraphs. The proposal of the centers is based on a combination of experience, know-how and sophisticated approach. The main fact influencing the concept of WTEC is the necessity to treat different types of wastes. Typical types of wastes as well as main products of the processes in a WTEC are shown in Figure 1."

Jan 1, 2008

By Tiezheng Li

Keywords: Laminate Composites; Mechanical Behavior; Damage Evolution The mechanical performance of Ti-6-4-Al3Ti metal-intermetallic laminate (MIL) composites synthesized by a reactive foil sintering technique was evaluated. Crack morphology of untested Ti-6-4-Al3Ti MIL composites has been characterized by optical microscopy. Mechanical tests were performed on Ti-Al3Ti metal-intermetallic laminate (MIL) composites and pure Al3Ti, and the principal mechanisms of damage initiation and accumulation were identified experimentally. The elastic properties and anisotropy of the laminates were calculated and successfully compared with Resonant Ultrasonic Spectroscopy (RUS) measurements. The effect of residual stress on the fracture toughness of the Ti-6-4-Al3Ti MIL composites was analyzed.

Jan 1, 2005

By Xuemei Zheng, Aiyuan Ma, Chao Liu, Guojiang Li, Chenyu Sun, Jinhui Peng, Libo Zhang, Yongguang Luo

In this paper, the removal of fluorides and chlorides from blast furnace dusts by water vapor enhanced microwave roasting was investigated, combined with the advantages of microwave selective heating and based on a thermodynamic analysis of zinc and lead halides. According to proposed reactions in the process, detailed experiments were systematically conducted to study the effect of roasting temperature, holding time, air flow, water vapor flow rates, and stirring speed on the efficiency of the removal of F and Cl. The results show that 97.26% of F and 64.23% of Cl could be separated when the condition of the roasting temperature of 650°C, stirring speed of 80 rpm, holding time at 60 min, air flow of 350 L/h and water vapor flow rate of 8 mL/min was optimized.

Jan 1, 2016