bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Corrosion Behavior of the Laser Gas Nitrided Ti-6Al-4V
Authors: Razavi R. Sh. , Gordani G.R. , Salehi M. , Man Hau Chung
Published: April 2010

Laser gas nitriding of Ti-6Al-4V alloy was carried out using a Nd:YAG pulsed laser under pure nitrogen environment at a flow rate of 30 l/min. The microstructure and corrosion behavior of the nitrided samples were examined using scanning electron microscopy, XRD, XPS, and anodic polarization tests in 2M HCl solution. For comparison, untreated samples were tested under the same conditions. After laser treatment, samples showed a relative flat surface with no problems of cracks or delamination of the alloyed tracks. Laser nitriding produced dendritic structures. The microstructure of the laser melted zone consisted of a thin continuous layer followed by a nearly perpendicular growth of dendrites. Below this a mixture of small dendrites and large needles with random orientation was produced. X-ray spectrum and XPS analyses from the surface of the laser nitrided specimen at different depth, confirmed that the thin top layer and large dendrites close to the surface corresponded to TiN. It can be also seen that the strong TiN peaks on the top surface gradually decrease with depth which suggests that the structure beneath the top surface is likely TiN0.3 and ά-Ti mixtures. In general, the corrosion potential of laser gas nitrided specimens was relatively nobler than the untreated sample. Furthermore, the proper laser nitrided specimen exhibited less corrosion current density, passivated more readily and also maintained a lower current density over the duration of the experiment. This was correlated with the formation of very thin, continuous TiNxOy film in an oxidation state that was confirmed by XPS analyses of the passive layers.
Characterization of Thermal Contact Resistance in Metal Micro-Textured Thermal Interface Materials Using Electrical Contact Resistance Measurements
Authors: Kempers R. , Robinson A.J. , Lyons A.
Published: April 2010

A novel Metal Micro-Textured Thermal Interface Material (MMT-TIM) has been developed to address a number of shortcomings in conventional TIMs. This material consists of a thin metal foil with raised micro-scale features that plastically deform under an applied pressure thereby creating a continuous, thermally conductive, path between the mating surfaces. One of the difficulties in experimentally characterizing MMT-TIMs however, is distinguishing the bulk thermal resistance of the MMT-TIM from the thermal contact resistance that exists where it contacts the test apparatus. Since these materials are highly electrically conductive, this study attempts to employ electrical contact resistance measurements to estimate their thermal contact resistance. Tests using flat silver and gold specimens of known bulk thermal conductivity were used to develop a correlation between electrical and thermal contact resistance. This relationship was then employed to estimate the thermal contact resistance of a prototype silver MMT-TIM and indicates the thermal contact resistance accounts for approximately 10% of the measured thermal contact resistance. A number of issues related to this technique are discussed as well as its future outlook.
The Nature of the Vacancy-Wind Effect Occurring in Diffusion via Six-Jump-Cycles in B2 Intermetallics
Authors: Belova Irina V. , Murch Graeme E.
Published: April 2010

First discovered by the late Dr John Manning, the vacancy-wind effect is a subtle phenomenon that occurs when two or more atomic species compete for vacancies in a net vacancy flux. The vacancy-wind effect is incorporated in (for example) the vacancy-wind or Manning factor that appears in the Darken-Manning Equation relating the interdiffusivity, the tracer diffusivities and the thermodynamic factor. The mechanism of the vacancy-wind phenomenon has long been very poorly understood. Recently, a moving reference frame Monte Carlo method was used to illustrate graphically how the vacancy-wind effect operates in both ionic conductivity in an ionic solid with a dilute solute and chemical interdiffusion in concentrated alloys and ionic compounds. That strategy is extended in this paper to show graphically how the vacancy-wind effect operates in interdiffusion in a stoichiometric intermetallic taking the B2 structure. A simple 4-frequency vacancy diffusion model is used. In previous work, it was shown that depending on composition and temperature, this model can exhibit the six-jump-cycle mechanism. It is shown that in the limit of perfect order that there is no vacancy-wind effect associated with this mechanism when both types of cycle operate equally (zero net vacancy flux). The non-unity value of the vacancy-wind factor found for this mechanism under zero vacancy flux conditions is purely a consequence of a particular geometric mix of tracer and collective atom displacements. The concept that a non-zero off-diagonal phenomenological coefficient provides the vacancy-wind effect is verified.
Properties and Characterization of Hard Coatings Obtained by Boriding: An Overview
Authors: Campos-Silva Ivan , Ortíz-Domínguez M. , Martínez-Trinidad José , López-Perrusquia N. , Hernández-Sánchez E. , Ramírez-Sandoval Giselle , Escobar-Galindo Ramon
Published: April 2010

Some physicochemical and mechanical properties of surface hard coatings obtained by the paste-boriding process are summarized in this work. Different grades of borided ferrous alloys were used to develop the formation of surface layers type Fe2B or FeB/Fe2B. Furthermore, in order to characterize the nature of boride layers, some classical techniques are presented and discussed such as Glow Discharge Optical Emission Spectrometry (GDOES), Atomic Force Microscopy (AFM) and estimation of residual stresses by X-Ray Diffraction method. Also, the morphology of borided interfaces was evaluated by concepts of fractal theory.
Structural Phase Transitions in Mechanoactivated Manganese Oxides
Authors: Fishman Anatoly Yakovlevich , Ivanov M.A. , Petrova S.A. , Zakharov Robert Grigorievich
Published: April 2010

An investigation has been undertaken of the structural characteristics of the manganese oxides to understand these characteristics affected by mechanochemical treatment conditions. Chemically pure manganese (II, III) oxides and their mixtures were used as the initial components.
Site Preference and Diffusion in Ni3Al Alloyed with Ir, Ta or Re at 1200°C
Authors: Garimella N. , Choi H.J. , Sohn Yong Ho
Published: April 2010

Diffusion in L12-Ni3Al with ternary alloying additions of Ir, Ta and Re was investigated at 1200°C using solid-to-solid diffusion couples, and examined with respect to site preference in ordered intermetallic compound. In addition to determination of average ternary interdiffusion coefficients [1-3], average effective interdiffusion coefficients were determined directly from the experimental concentration profiles. Ni has the largest magnitude of average effective interdiffusion coefficient, followed by Al, Ir, Re and Ta. The average effective interdiffusion coefficients for Ir, Re and Ta are much smaller than those for Ni and Al. Tracer diffusion coefficients determined by extrapolation technique, and available literature also followed the same trend. The relative tendency of Ni, Al, Ir, Re and Ta to occupy the -Ni and -Al sites are correlated to these diffusion coefficients, with due consideration for diffusion mechanisms and coordination of atoms.
Molecular Dynamics Calculations of InSb Thermal Conductivity
Authors: de Oliveira Cardozo Giovano , Rino José Pedro
Published: April 2010

Equilibrium and non-equilibrium molecular dynamics calculations of thermal conductivity coefficient are presented for bulk systems of InSb, using an effective two- and three-body inter atomic potential which demonstrated to be very transferable. In the calculations, the obtained coefficients were comparable to the experimental data. In the case of equilibrium simulations a Green-Kubo approach was used and the thermal conductivity was calculated for five temperatures between 300 K and 900 K. For the non equilibrium, or direct method, which is based on the Fourier’s law, the thermal conductivity coefficient was determined at a mean temperature of 300K. In this case it was used a pair of reservoirs, placed at a distance L from each other, and with internal temperatures fixed in 250 K, for the cold reservoir, and 350 K for the hot one. In order to obtain an approach to an infinite system coefficient, four different values of L were used, and the data was extrapolated to L→∞.
Anisotropy of Boride Layers: Effect on the Mechanical Properties of AISI 4140 Borided Steels
Authors: Campos-Silva Ivan , López-Perrusquia N. , Hernández-Sánchez E. , Ortíz-Domínguez M. , Bravo-Bárcenas D. , Martínez-Trinidad José
Published: April 2010

The growth of iron borides over the surface of different steels is of high anisotropy. It was determined that the anisotropy of borided phases reveals a significant instability of properties in service. One of the techniques to determine the effect of anisotropy on the mechanical properties of boride layers is the induced-fracture by Vickers microindentation. During the present work, the fracture toughness (KC) of the Fe2B hard coatings has been estimated at the surface of AISI 4140 borided steels. The force criterion of fracture toughness was determined from the extent of brittle cracks originating at the tips of an indenter impression. The indentation loads were established between 1.9 to 9.8 N at three different distances from the borided surface. The KC values were expressed as a function of temperature, treatment time and the indentation distances from the surface. Likewise, the adherence of the coated system was evaluated by Rockwell-C indentation, where the borided steel showed sufficient adhesion.
Effect of Solid Thickness on Transient Heat Conduction in Workpieces Irradiated by a Moving Heat Source
Authors: Bianco Nicola , Manca Oronzio , Nardini Sergio , Tamburrino Salvatore
Published: April 2010

In this paper a three dimensional conductive field is analyzed and solved by means of the COMSOL Multiphysics code. The investigated work-pieces are made up of a simple brick-type solid. A laser source with combined donut-Gaussian distributions is considered moving with a constant velocity along motion direction. The solid dimension along the motion direction is assumed to be infinite or semi-infinite, while finite width (2ly) and thickness (s) are considered. Thermal properties are considered temperature dependent and the materials are considered isotropic. Surface heat losses toward the ambient are taken into account. Results are presented in terms of profile temperature to evaluate the effect of solid thickness.
Proposed Model of Water Adsorption/Desorption in a PEM Membrane
Authors: Tosto Sebastiano , Knauth Philippe , Di Vona Maria Luisa
Published: April 2010

This paper describes the processes of water adsorption and desorption in PE membranes for fuel cells. A simple equation is inferred assuming that the surface of the membrane is uniformly covered by adsorbed molecules to an average depth of some monolayers. The adsorption depth is only controlled by diffusion of adsorbate from the surface towards the bulk through a two-layer or multi-layer mechanisms; so the empty sites formed at the surface can accept further molecules of water. If the diffusion rate is fast enough, cumulative water uptake occurs. The uptake kinetics is described considering the average penetration depth, i.e. neglecting the local concentration spikes below a random number and position of empty sites statistically formed at the surface of the membrane. The model also describes the desorption process, assumed to start at a prefixed time.
Surface Roughness and Initial Pressure Effect on Superplastically Carburized Duplex Stainless Steel
Authors: Azis Sharidah Azuar Abdul , Jauhari Iswadi , Masdek Nik Rozlin Nik , Ahamad Nor Wahida , Ogiyama Hiroyuki
Published: April 2010

Superplastic carburizing (SPC) is a carburizing process that combines carburizing with superplastic deformation. Since SPC involves direct interaction between the superplastically deformed surface and the solid carbon medium, the effect of surface roughness on the process cannot be disregarded. This paper presents the study of surface roughness and initial pressure effects on superplastic carburizing of duplex stainless steel (DSS). SPC was conducted under four different surface roughness (Ra) conditions of 0.9, 0.3, 0.1 and 0.03 μm. The microstructure, surface hardness, and carburized layer thickness were studied. Comparisons were also done on non-superplastic material which has a coarse microstructure. The results showed that the surface roughness strongly affected the properties of the superplastically carburized duplex stainless steel while its effects on the non-superplastic material were not that obvious.
Numerical Study of a Vertical Solidification Process under Magnetic Field in Unsteady State
Authors: Nouri Sabrina , Benzeghiba Mouhamed , Benzaoui Ahmed
Published: April 2010

Numerical computation is achieved in an axisymmetric configuration to analyze the magnetic field effect on thermosolutal convection during vertical solidification of a binary alloy. The bath is exposed to a uniform temperature profile in unsteady state. During the growth three regions appear: liquid, mushy and solid zones. The mushy zone is assimilated to porous medium. A mathematical model of heat, momentum and solute transfer has been developed in primitive variables (pressure-velocity). A single domain approach (enthalpy method) is used to build the equations system. In this context, a computer code has been developed and validated with previous studies. The results in term of stream function and solute concentration show the strong effect of the magnetic field on the fluid flow and on the solutal stratification. The effects of magnetic field and melt convection intensity were demonstrated. The main results show that the quality of highly doped binary alloy crystals can be improved when the growth process occurs at low pulling rates and under a magnetic field.
An Approach for Analyzing the Growth Kinetics of Fe2B Phase on AISI 1018 Steel
Authors: Keddam Mourad
Published: April 2010

A simulation of the growth kinetics of iron boride forming on AISI 1018 carbon steel was done on the basis of a kinetic model. This model including the effect of the incubation time during the formation of iron boride, was applied in order to evaluate the kinetic constant at the ( ) interface, the layer thickness and the mass gain depending on the paste-boriding parameters such as time, temperature and boron potential reflected by the corresponding value of the surface boron content. The simulation results were found to be in a good agreement with the experimental data derived from the literature.
Diffusion of Ti, V and Nb in Ni3Al at Elevated Temperatures
Authors: Fukaya Haruhiko , Moniruzzaman Md. , Murata Yoshinori , Morinaga Masahiko , Koyama Toshiyuki , Hashimoto Wataro , Tanaka Katsushi , Inui Haruyuki
Published: April 2010

Interdiffusion coefficients of Al replacing elements in Ni-Al-X (X=Ti, V and Nb) were estimated by a series of experiments using diffusion couples of Al rich pseudo-binary systems at three different temperatures of 1423, 1473 and 1523K. In order to obtain interdiffusion coefficients of the pseudo-binary systems, the experimental data was analyzed by the Sauer and Freise method, and also impurity diffusion coefficients of Ti, V and Nb in Ni3Al were estimated by applying the Darken-Manning equation. The magnitude of interdiffusion coefficient decreased in order of V, Ti and Nb at all three temperatures. Impurity diffusion coefficients were described by the expressions: , , . The activation enthalpies obtained from the experimental data confirmed the retardation of Ti, V and Nb diffusion in Ni3Al by the anti-site diffusion mechanism. These results are consistent with our previous work on diffusion of Re and Ru in Ni3Al .
Glycolic Acid Ethoxylate 4-Tert-Butylphenyl Ether as Drag Reducing Agent in Aqueous Media Flow
Authors: Bari Hayder A. Abdul , Suali Emma , Bin Hassan Zulkafli
Published: April 2010

Glycolic acid ethoxylate 4-tert-butylphenyl ether was used as investigated anionic surfactants in this experimental work. A built up rig with ratio of pipe length to diameter (L/D) is equal to 59 was used to achieve the purpose of this work which is to investigate the drag reduction in turbulent flow with different flow rates and concentration of additive. In the present study, the concentrations (ppm) of additive were analyzed starting from 200, 300, 400, 500 and 600, respectively. The flow rates (Re) of the solution were from 11235, 22470, 33705, 44940, 56175, 67410 and 78645, respectively. It was found that glycolic acid ethoxylate 4-tert-butylphenyl ether is capable to reduce the drag less than 10 %. The highest drag reduction is 8 % was achieved in 600 ppm of solution for turbulent flow with Re within the range 44940 to 56175. The results of experimental work shows that this anionic surfactant perform as a poor drag reducing agent due to its drag reduction values increases only 1 to 3 % even though the concentration of solution was added about 100 ppm. This occurred probably because of the formation of micelle in the solution which is not in a fully threadlike forms and the micelle networks are not fully established in solution to surpassed the degree of turbulent flow.
Heat Diffusion in Solidifying Alumina Splat Deposited on Solid Substrate under Plasma Sprayed Conditions: Application to Coating Formation
Authors: Lahmar-Mebdoua Y. , Vardelle A. , Fauchais Pierre , Gobin D.
Published: April 2010

A plasma-sprayed coating is built up by the layering of individual splats. The latter are formed by spreading and solidification of molten particles sprayed onto a solid substrate. The coating properties depend on its microstructure and the quality of contact between the splats and the underlying layer and between the piled-up splats. This work deals with a 1D model of heat transfer between plasma-sprayed alumina splat and smooth substrate. The model is based on heat diffusion in the solidifying splat and substrate and includes undercooling phenomenon, heterogeneous nucleation and crystal growth kinetics. It assumes that splat spreading and solidification are two independent processes. The model predicts splat cooling and solidification taking into account, as far as possible, the in-flight particle properties drawn from the literature in order to study their effect on splat thermal history. The effect of the quality of contact between the splats as well as the already-deposited and solidified layer thickness on the grain size distribution and front solidification velocity is investigated.
Study on the Growth of Nb3Sn Superconductor in Cu(Sn)/Nb Diffusion Couple
Authors: Kumar A.K. , Laurila T. , Vuorinen V. , Paul Aloke
Published: April 2010

Nb3Sn growth following the bronze technique, (i.e. by interdiffusion between Cu(Sn) alloy (bronze) and Nb) is one of the important methodologies to produce this superconductor. In this study, we have addressed the confusion over the growth rate of the Nb3Sn phase. Furthermore, a possible explanation for the corrugated layer in the multifilamentary structure is discussed. Kirkendall marker experiments were conducted to study the relative mobilities of the species, which also explained the reason for finding pores in the product phase layer. Based on the parabolic growth constant at different temperatures, the activation energy for the growth is determined. We have further explained the dramatic increase in the growth rate of the product phase by changing just one atomic percentage of Sn in the Cu-Sn bronze alloy.
Evaluations of Hydrogen Permeation on Al2O3-CuO-ZnO-Based Cobalt Composite Membrane
Authors: Park Ji Hee , Hong Tae Whan , Jung Mie Won
Published: April 2010

Hydrogen has attracted clean energy media as a high-quality and renewable energy source in recent years. On the one hand, a ceramic catalyst and/or catalyst support such as Al2O3 has often been a preferred choice due to their specific properties such as thermal stability and high surface area. Al2O3-CuO-ZnO was synthesized by using the sol-gel process with aluminum isopropoxide and primary distilled water as the precursor and solvent. In this synthesized process, metal oxides caused to precursors such as copper and zinc nitrate were added. To prepare membranes, cobalt metal powder was used to increase the strength and durability. The Al2O3-CuO-ZnO/Co composite membranes were produced using hot press sintering for consolidation of powders following reactively mechanical alloying process. The characterizations of membrane were measured XRD, FE-SEM and EDS. Hydrogen permeation evaluations were examined at a room temperature to 773 K under increasing pressure. Hydrogen permeation rate was obtained with 0.18 mol m-2 s-1 at 773 K result from complex diffusion mechanism such as Sievert’s type, Knudsen diffusion and/or molecular sieving.
New Photothermal Deflection Method to Determine Thermal Properties of Bulk Semiconductors
Authors: Gaied Imen , Lassoued Salima , Genty Fredéric , Yacoubi Noureddine
Published: April 2010

In this paper, we present a new Photothermal Deflection Technique (PTD) to determine thermal properties of bulk doped or undoped semiconductor such as GaAs, GaSb, InAs, etc. The method proposed here consists in covering the sample with a thin graphite layer in order to increase the photothermal signal and to ovoid any reflection on the sample surface. This method deals with the analysis of the logarithm of amplitude and phase variation of the photothermal signal versus square root modulation frequency where the sample placed in air is heated by a modulated light beam coming from a halogen lamp. So the best coincidence between experimental curves and corresponding theoretical ones gives simultaneously the best values of thermal conductivity and thermal diffusivity of the sample. These obtained values are in good agreement with those found in literature. The advantage of applying this method in this way lies in its simplicity and its sensibility to both thermal conductivity and thermal diffusivity.
Microstructural Study of a High Bainite Dual Phase (HBDP) Steel Austempered at Different Temperatures
Authors: Bakhtiari R. , Ekrami A.
Published: April 2010

4340 steel bars were austenitized at 850oC for 1 hour followed by heating at 700oC (ferrite and austenite region) for 90 min and quenching into a salt bath with different temperatures of 300, 350, 400 and 450oC. The steel bars were held for 1 hour at these temperatures before air cooling to room temperature. Various ferrite-bainite microstructures with 34% volume fraction of ferrite and different bainite morphologies were obtained. The results of SEM studies showed that by increasing the austempering temperature, the morphology of bainite varies from lower to upper bainite. According to the T-T-T diagram of the studied steel, the bainite transformation will not complete for the holding time of 1 hour at 400 and 450oC austempering temperatures and there can be 9 and 23Vol% of martensite at these temperatures respectively. Microstructural studies of specimens austempered at these temperatures showed complex microstructures of ferrite, bainite and martensite. Mechanical testing results showed reduction in yield and ultimate tensile strengths, hardness, uniform and total elongations and impact energy with increase of the austempering temperature from 300 to 400oC. But for dual phase steel austempered at 450oC, the yield and tensile strengths and hardness increased and a severe reduction in total elongation and impact energy was obtained. This brittle behaviour was related to martensite formation during cooling from this austempering temperature.
Heat and Mass Transfers and their Mutual Effects in Membrane Processes
Authors: Min J.C. , Su M.
Published: April 2010

A mathematical model was developed to describe the coupled heat and mass transfers in membrane processes. Equations for the heat and mass transfer resistances were derived and the coupling effects of the heat and mass transfer were analyzed. With taking the membrane separation process of moist air as an example, the effects of air temperature and water vapor concentration on the heat and moisture transfer process were investigated. The results show that neither the thermal resistance nor the moisture resistance are constant, they are affected by not only the membrane parameters but also the air state. As the temperature difference between the two airstreams separated by the membrane increases, both the thermal and moisture resistances decrease, causing an improved heat and mass transfer. As the average temperature of the two airstreams increases, the thermal resistance remains almost constant while the moisture resistance decreases significantly. Further, as the water vapor concentration difference between the two airstreams increases, both the thermal and moisture resistances increase. As the average water vapor concentration of the two airstreams increases, the thermal resistance remains unchanged while the moisture resistance decreases.
An Improved Method for Evaluating the Moisture Diffusivity in a Membrane
Authors: Hu T. , Min J.C. , Song Y.Z.
Published: April 2010

A method that combines the experimental measurements and numerical simulations to determine the moisture diffusivity in a membrane has been developed. An experimental set-up was designed and constructed to measure the total moisture resistance. The test section consists of an airflow channel, a membrane, and a water tank, which form a sandwich structure. The process of moisture transport from the water surface to the airstream in the channel is numerically simulated to obtain the variation of the total moisture resistance with the moisture diffusivity in the membrane, which is then determined by comparing the experimental and numerical total moisture resistances. There are three features with the present method, i.e., simple structure of the test section, combination of the experiment and simulation, and consideration of the boundary layer resistances on both sides of the membrane. Tests were conducted on two PVDF membranes with 0.22 and 0.45 μm mean pore diameters. The results show that the moisture diffusivities in both membranes are in the order of 10-6 kgm-1s-1, with a larger pore size tending to yield a larger diffusivity. The moisture diffusivities in both membranes are insensitive to the airflow rate.
Structural Relaxation Process by Addition of B in CuHfTi Amorphous Alloys
Authors: Yamada Kazumasa , Miura N. , Yamamoto A. , Figueroa I.A. , Davies Hywel A. , Todd Iain
Published: April 2010

The aim of this research is to clarify a quantitative evaluation in the structural relaxation processes focusing on the activation energy on the addition of B to Cu-based amorphous alloys. The activation energy for structural relaxation process in a metal type amorphous CuHfTi ternary and CuHfTiB quaternary alloys, with cross sections of typically 0.03 mm x 2.0 mm, prepared by chill-block melt spinning has been investigated by Differential Scanning Calorimetry (DSC) with a cyclically heating technique. Activation energies for structural relaxation with a spatial quantity in amorphous materials have been discussed by use of a total relaxed ratio function that depends on annealing temperature and time. In the present work on CuHfTi ternary and CuHfTiB quaternary alloys, the distributions for the Activation Energy Spectrum (AES) by calculation with derivative-type relaxed ratio function were observed almost 160 kJmol-1, whereas in difference for shape only in the CuHfTi-B3% quaternary alloy. Another result has been also established that the ‘reversible’ AES model energy distribution though the cyclically structure relaxation occurs even in amorphous CuHfTiB alloy system.
Three-Dimensional Study of Heat and Mass Transfer in a Partially Porous Elongated Cavity
Authors: Mimouni N. , Chikh Salahs , Bennacer Rachid
Published: April 2010

A 3D numerical analysis is carried out to investigate heat and mass transfer in a partly porous cavity of high aspect ratio. The goal is to determine the best physical and geometrical parameters that allow optimal heat and mass transfer rate in such domain used in a solar adsorption cooling system. The computational domain consists of a tall cavity heated on the left vertical wall and cooled on the opposing wall. The SIMPLE algorithm is used to handle the velocity pressure coupling. Simulation results allow determining the optimal configuration of the used porous substrate and plain fluid position in the cavity in order to optimize the performance of such solar adsorption cooling installation.
Surface Microstructure Evolution during Phase Transformation on Mn, Al and Si Alloyed Ultra Low Carbon Steel
Authors: Gautam Jai , Petrov Roumen H. , Leunis Elke , Kestens Leo A.I.
Published: April 2010

This paper investigates the surface texture evolution after a short phase transformation annealing in low vacuum on ultra low carbon steel sheets alloyed with high Mn and Al and the cold rolled steel sheets of industrial composition alloyed with silicon. The ultra low carbon steel sheets with high Mn and Al show surface monolayer which has a characteristic surface texture components <100>//ND texture and microstructure with special grain morphology. Contrastingly, the industrial composition alloyed with silicon does not show specific surface texture components inspired by surface energy anisotropy at the surface. The composition depth profiling investigations performed on the all steel sheet surface shows that oxidation characteristics of alloying elements at the metal vapour interface have played a decisive influence on surface texture evolution. Further, transformation annealing in higher vacuum reveals that surface texture can be obtained in an industrial composition alloyed with silicon.
Depth Resolved and Elemental Selective XRF and XAS in Surface Layer of Annealed Fe-Cr Alloys
Authors: Shinoda Kozo , Sato S. , Suzuki Shigeru , Toyokawa Hidenori , Tanida Hajime , Uruga Tomoya
Published: April 2010

Cr in Fe-Cr alloys often forms some different phase of oxides during annealing at high temperatures. The phases of Cr oxides are determined depending on the annealing condition such as temperature and oxygen partial pressure. In this study, depth-resolved X-ray fluorescence analysis (XRF) of Fe and Cr were carried out using a two-dimensional pixel array detector with geometrical arrangement of the grazing exit in detection of fluorescence X-ray emitted from the sample surface, in order to characterize the depth-directional distribution of the elements in the surface layers of Fe-Cr alloys annealed under low oxygen partial pressure. In addition, depth-resolved X-ray absorption spectra will also be able to be obtained by measuring the incident X-ray energetic dependencies of the fluorescence intensity. These techniques facilitate non-destructive measurement of the elemental distribution and the phase of metal or oxides in depth direction. The experiments were performed at the BL01B1 of SPring-8 synchrotron radiation facility. The results showed that Cr was enriched and covered on the surface of the alloys during annealing and formed as Cr2O3 or FeCr2O4. The phase and thickness of formed oxides depended on the alloy composition and the annealing conditions.
The Effect of TaN Interlayer on the Performance of Pt-Ir Protective Coatings in Glass Molding Process
Authors: Chien His Hsin , Ma Kung Jeng , Kuo Chien Huang , Huo Cheng Bang , Chao Choung Lii , Chen Ying Tung
Published: April 2010

The glass molding process provides great potential for mass production of precise glass optical components at low cost. The key issue for achieving a low production cost is to extend the service life of the expensive mold inserts. The precious metal based alloy is one of the coating materials for the molds which provides excellent glass anti-sticking results. However, the inter-diffusion between the WC/Co mold materials and precious metal coatings will deteriorate the coatings which needs to be resolved. It is essentially to deposit an interlayer as the diffusion barrier to improve the inter-diffusion problem. A thin layer of TaN was deposited on the WC/Co substrate as the diffusion barrier using a magnetron sputtering system, and followed by the deposition of Pt-Ir layer as the protective layer. Low Tg Glass gobs (L-BAL 42) were placed on the coated substrate to investigate inter-diffusion between the substrate and coating at high temperature. The surface interaction between the glass gobs and protective coatings was also examined. The obtained TaN and Pt-Ir multilayer had a dense nano-crystalline structure. High temperature wetting tests showed that the TaN film could effectively resist the cobalt and tungsten diffusion into the precious metal protective layer and, as a result, minimized the possibility of oxidation and interaction between glass and protective coating. The coated substrates retained a good surface finish and the glass gobs stayed fully transparent after 6 hours reaction test at 700°C.
Improvement of the Electrochemical Properties in Nano-Sized Al2O3 and AlF3-Coated LiFePO4 Cathode Materials
Authors: Ahn C.W. , Ha M.G. , Hong K.S. , Lee D.J. , Doh Chil Hoon , Doh K.Y. , Na J.M. , Song B.H. , Jeon H.M. , Cho Y.G. , Yang H.S. , Jeong E.D.
Published: April 2010

The surface conditions of LiFePO4 powder were modified by adding AlF3 and Al2O3 by using the sol-gel process to improve its electrochemical properties. The surface of LiFePO4 powders was partially covered with nano-sized AlF3 and Al2O3, which is confirmed by using a transmission electron microscope image. The states of coated Al materials were examined by using X-ray photoelectron spectrometer results. The nano-sized AlF3- and Al2O3-coated LiFePO4 powders showed no difference in the bulk structure compared with the pristine one. However, the AlF3- and Al2O3-coating on LiFePO4 powders improved the overall electrochemical properties such as the discharge capacity, the cyclability, and the rate capability compared with those of a pure LiFePO4. Such enhancements were attributed to the presence of a stable AlF3 and Al2O3 layer which acts as an interfacial stabilizer on the surface of LiFePO4 powders.
Effect of the Separating Distance of Twin Buildings on the Generated Flow Structure
Authors: Bhouri Baouab Inès , Mahjoub Said Nejla , Mhiri Hatem , Le Palec Georges , Bournot Philippe
Published: April 2010

The present work consists in a numerical examination of the dispersion of pollutants discharged from a bent chimney and crossing twin similar cubic obstacles placed in the lee side of the source. The resulting flow is assumed to be steady, three-dimensional and turbulent. Its modelling is based upon the resolution of the Navier Stokes equations by means of the finite volume method together with the RSM (Reynolds Stress Model) turbulent model. This examination aims essentially at detailing the wind flow perturbations, the recirculation and turbulence generated by the presence of the twin cubic obstacles placed tandem at different spacing distances (gaps): W = 4 h, W = 2 h and W = 1 h where W is the distance separating both buildings.
Numerical Simulations on the Growth of Thin Oxide Films on Aluminum Substrates
Authors: Perron Aurelien , Garruchet Sébastien , Politano Olivier , Aral G. , Vignal Vincent
Published: April 2010

We investigated the oxidation of nanocrystalline aluminum surfaces by using variable charge molecular dynamics at 600 K under three oxygen pressures: 1, 10 and 20 atm. The interaction potential was described by the electrostatic plus (Es+) model that allows dynamical charge transfer among atoms. We mainly focused on the effect of the oxygen pressure on the oxidation kinetic, the chemical composition and the microstructure of the oxide films formed. The results show that oxidation kinetics as well as chemical composition and microstructure depend on the applied oxygen pressure. The oxide film thickness tends to a limiting value equal to ~3 nm. Finally, we obtained a partially crystalline oxide films for all oxygen pressures and we observed that the degree of crystallinity increases with time.
Old and New Insights in the Treatment of Thyroid Carcinoma
Authors: Gasent Blesa Joan Manel , Grande Pulido Enrique , Provencio Pulla Mariano , Alberola Candel Vicente , Laforga Canales Juan Bautista , Grimalt Arrom Miguel , Martin Rico Patricia
Published: April 2010

Thyroid cancer is the endocrine tumor that bears the highest incidence with 33 550 new cases per year. It bears an excellent prognosis with a mortality of 1530 patients per year (Jemal et al.; 2007). We have been treating patients with thyroid carcinoma during many years without many innovations. Recently, we have assisted to the development of new agents for the treatment of this disease with unexpected good results. Here we present a review with the old and new methods for the treatment of this disease.
Evidence‐based policy: where is our theory of evidence?
Authors: Cartwright Nancy , Goldfinch Andrew , Howick Jeremy
Published: April 2010

This article critically analyses the concept of evidence in evidence‐based policy, arguing that there is a key problem: there is no existing practicable theory of evidence, one which is philosophically‐grounded and yet applicable for evidence‐based policy. The article critically considers both philosophical accounts of evidence and practical treatments of evidence in evidence‐based policy. It argues that both fail in different ways to provide a theory of evidence that is adequate for evidence‐based policy. The article contributes to the debate about how evidence can and should be used to reduce contingency in science and in policy based on science.
Technology, evidence and professional practice: reflections on the Integrated Children's System
Authors: Shaw Ian , Clayden Jasmine
Published: April 2010

Through the results from part of a formative evaluation in England and Wales of the Integrated Children's System, the authors aim to illustrate the diverse ways in which policy, technology and practice interests challenge conventional assumptions regarding the construction and use of evidence in children's services. We identify four connected consequences of the ICS for practice. The ICS actively shapes practice, brings issues into focus, renders social work visible and distances the services user. We interpret the findings in terms of the persistence and diversification of professional discretion and the interplay of standardisation and case‐based practice. We challenge some accepted academic understandings of the relationship between technology and professional practice.
Disseminators vs revisionists: attitudes to the ‘implementation gap’ in evidence‐based practice
Authors: Midgley Nick
Published: April 2010

Ambiguities in the term ‘evidence‐based practice’ (EBP) are often used to hide some of the tensions within the idea itself. This article seeks to clarify what EBP means and how evidence and knowledge can contribute to the development of children's services. It acknowledges the ‘implementation gap’ between evidence‐based practice and evidence‐based practitioners, and discusses two contrasting perspectives on the problem and its solution. For ‘disseminators’ the primary issue is better translation of findings into practice, illustrated here by the work of the National Institute of Health and Clinical Excellence (NICE). ‘Revisionists’ look beyond obstacles and drivers to implementation and instead advocate looking again at the relationship between research and practice and propose a number of radical proposals for how this relationship can be re‐envisioned.
Children Acts 1948‐2008: the drivers for legislative change in England over 60 years
Authors: Jones Ray
Published: April 2010

The article explores the drivers for legislative and policy change in children's social care in England over the past 60 years. It describes the factors that led to the major children's social care legislation and explores how these ‘drivers for change’ varied in their importance over time. Particular attention is given to the impact of research evidence as a driver for change among, for example tragedy and media scandal, political developments and changes in practice prompting legislative reform. The article also notes how research has at times provided a background for change while not explicitly promoting the change itself. The use of performance information and research in shaping and monitoring change is seen to have increased in the past 30 years, but with continuing tensions between a natural and necessary research timescale and the political wish for quick and clear answers to pressing issues.
Lessons from Columbine: effective school‐based violence prevention strategies and programmes
Authors: Elliott Delbert
Published: April 2010

On 20 April 1999, at Columbine High School in Colorado, two students, Eric Harris (aged 18) and Dylan Klebold (17), embarked on a massacre, killing 12 students and one teacher. The pair then committed suicide. The event provoked vigorous debate around topics such as the gun culture, bullying, violent video games, goth culture and teenage use of the internet and anti‐depressants. In nearby Boulder is the Center for the Study and Prevention of Violence, part of the University of Colorado. Del Elliott, a world‐renowned criminologist and sociologist, has been director there since 1993. Columbine was the catalyst for Del and a team of researchers, policy‐makers and practitioners to develop the Blueprints for Violence Prevention database of evidence‐based programmes. On 2 July 2009, Del gave the annual Social Research Unit, Dartington, lecture at the Commonwealth Club in London. This article is based on his talk.
Standards, Equity, and Advocacy: Employment Conditions of ESOL Teachers in Adult Basic Education and Literacy Systems
Authors: SUN YILIN
Published: April 2010

In 2005, TESOL sponsored a survey to respond to the growing concerns of the organization's Adult Education Interest Section (AEIS). The results showed that interest section members were deeply concerned with inequitable workloads, less‐than‐desirable working conditions, heavy reliance on part‐time teachers, and much‐needed professional development opportunities and support in programs that serve adult English language learners. Previous studies in adult education have shown that such precarious employment patterns undermine the professionalism of the field because many educators have to contend with juggling several jobs, receiving low pay, and being prevented from improving their instructional practices or keeping abreast of current research (Gonzalez, 2009; Smith, Hofer, & Gillespie, 2001; Sun, Carosella, Carscadden, Stevens, & Lamb, 1996; Sun & Maum, 2006). This article reports on these working conditions in the hopes of gaining a better understanding of the issues and concerns that seem to be most pervasive in the field of adult English to speakers of other languages (ESOL). The study's findings will help to plan future directions for the AEIS membership and offer TESOL data to support its advocacy efforts in the field of adult ESOL.
Determination of Electronic Structure of Oxide–Oxide Interfaces by Photoemission Spectroscopy
Authors: Wang Hui‐Qiong , Altman Eric , Broadbridge Christine , Zhu Yimei , Henrich Victor
Published: April 2010

A method has been developed to use the finite escape depth of the photoelectrons emitted in ultraviolet photoemission spectroscopy (UPS) to determine the electronic density‐of‐states at the interface between two dissimilar metal oxides. Ultrathin films of one oxide are grown heteroepitaxially, one monolayer at a time, on a single‐crystal substrate of the other oxide, and UPS spectra are taken after each complete monolayer. By comparing experimental UPS spectra with calculated spectra based on specific models of the interfacial structure, the interfacial density‐of‐states can be extracted. The two oxide systems studied here are NiO–Fe3O4 and CoO–Fe3O4. The former system is found to have an atomically abrupt interface, with no significant density of interface states. For CoO, however, an interfacial electronic spectrum, different from that of either the substrate or the overlayer, is found. The spatial extent and possible origin of those interfacial states is discussed.
Enhanced process comprehension and quality analysis based on subspace separation for multiphase batch processes
Authors: Zhao Chunhui , Gao Furong , Niu Dapeng , Wang Fuli
Published: April 2010

Phase‐based subpartial least squares (subPLS) modeling algorithm has been used for online quality prediction in multiphase batches. It strictly assumes that the X–Y correlations are identical within the same phase so that they can be defined by a uniform regression model. However, the accuracy of this precondition has not been theoretically checked when put into practical application. Actually it does not always agree well with the real case and may have to be rejected for some practical processes. In the present work, it corrects the “absolute similarity” of subPLS modeling by a more general recognition that only one part of the underlying correlations are time‐wise common within the same phase while the other part are time‐specific, which is referred to as “partial similarity” here. Correspondingly, a two‐step phase division strategy is developed, which separates the original phase measurement space into two different parts, the common subspace and uncommon subspace. It is only in the common subspace where the underlying X–Y correlations are similar, a phase‐unified regression model can be extracted for online quality prediction. Moreover, based on the subspace separation, offline quality analyses are conducted in both subspaces to explore their respective cumulative manner and contribution in quality prediction. The strength and efficiency of the proposed algorithm are verified on a typical multiphase batch process, injection molding. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Global superstructure optimization for the design of integrated process water networks
Authors: Ahmetović Elvis , Grossmann Ignacio E.
Published: April 2010

We propose a general superstructure and a model for the global optimization for integrated process water networks. The superstructure consists of multiple sources of water, water‐using processes, wastewater treatment, and pre‐treatment operations. Unique features are that all feasible interconnections are considered between them and multiple sources of water can be used. The proposed model is formulated as a nonlinear programing (NLP) and as a mixed integer nonlinear programing (MINLP) problem for the case when 0–1 variables are included for the cost of piping and to establish optimal trade‐offs between cost and network complexity. To effectively solve the NLP and MINLP models to global optimality we propose tight bounds on the variables, which are expressed as general equations. We also incorporate the cut proposed by Karuppiah and Grossmann to significantly improve the strength of the lower bound for the global optimum. The proposed model is tested on several examples. © 2010 American Institute of Chemical Engineers AIChE J, 2011