bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Behavior and Thickness of Aluminium Oxide Films Studied by EIS: Laboratory and Field Studies
Authors: Habib Khaled , Al-Muhanna K. , Al-Sabti F. , Al-Arbeed A.
Published: May 2012

The technique of electrochemical impedance spectroscopy (EIS) is widely used in laboratories and industries for materials evaluation. The aim of this investigation is to monitor the thickness of the anodized (oxide) aluminium sheets (samples) by using the EIS in a laboratory and a field study at a predetermined exposure duration in the field, i.e., 0, 1, 3, 6, 9, 12 months, in 0-10 % sulphuric acid. Four experimental stations were built out of KISR in order to monitor the thickness of the anodized (oxide) layer and the electrochemical parameters of anodized aluminium sheets by using the EIS. The zero state results at 0 exposure duration, indicating that as the concentration of the sulphuric acid increased from 0-10% H2SO4, the polarization resistance was observed to decrease from 3.15E+05 to 9.80E+03 Ohms, except at a concentration of 4% H2SO4, where the polarization resistance was observed to increase from 5.20E+03 to 2.90E+04 Ohms. On the contrary, the value of the solution resistance was observed to vary several times between 1.33E+04 to 1.53E+00 Ohms as a function of the increase of the sulphuric acid concentration from 0-10% H2SO4. In similar fashion to the polarization resistance, as the concentration of the sulphuric acid increased from 0-10% H2SO4, values of the alternating current impedance were found to vary several times between 1.94E+09 to 3.95E+05 Ohms, in a non-linear fashion. A similar behavior was observed on the values of the double layer capacitance as a function of the sulphuric acid increased, from 0-10% H2SO4, in which the values of the double layer capacitance was observed to change several times from 2.24E-09 to 2.53E-06 μF. The optimum thickness of the oxide film was detected (26.5 nm) at 8% H2SO4 of the sulphuric acid concentration. In order to determine the performance of the anodized aluminium-sheet in surrounding areas of Kuwait, a plan was arranged for such a field study. The field study consists of setting up four racks of sample panels in different locations in Kuwait. The racks were installed in the main field of Kuwait Institute for Scientific Research (KISR) in Shuwaikh area, in a residential area of South Sura area, in the main field of the Petroleum Research Department and Studies Center (PRSC) of Kuwait Institute for Scientific Research (KISR), in an industrial area of Ahmadi city, and in the main field of the fishery department of Kuwait Institute for Scientific Research (KISR) in a marine area of Salmia. The investigation planned to take a sheet each three months, for a 12 months duration, in order to determine the electrochemical parameters and the oxide film thickness of the sheets by the EIS technique in the field and to compare the data with those obtained in this report, at zero state.
CuO Nanoparticles: A Mild and Efficient Reusable Catalyst for the One-Pot Synthesis of 4-amino-5-pyrimidinecarbonitriles under Aqueous Conditions
Authors: Ahmadi Seyed Javad , Sadjadi Sodeh , Hosseinpour Morteza
Published: May 2012

An efficient method for the synthesis of 4-amino-5-pyrimidinecarbonitriles by three-component reaction of malononitrile, aldehydes and N-unsubstituted amidines, under aqueous conditions, using CuO nanoparticles as catalyst is reported. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst.
Effect of Salt Bath Composition on the Chromium Diffusion on Plain Carbon Steels by TRD Process
Authors: Ghadi A. , Soltanieh Mansour , Karimi Zarchi H.R.
Published: May 2012

The thermo-reactive diffusion (TRD) process is used for diffusing an element to the metallic steel substrate. TRD is carried out by using either salt bath or fluidized bed methods. In this research, the molten salt bath method is used. Ferro chromium was dissolved in the molten borax as the source of chromium in the salt. Samples of cylindrical shape of plain carbon steel with 10 mm diameter and 20 mm height were treated at 1000°C for 14 hours in different baths including either low carbon ferro chromium (LCFC) or high carbon ferro chromium (HCFC) powder. The purpose of this research is to investigate the effect of the salt bath composition on the diffusion of chromium and formation of chromium compound layer on plain carbon steel by using the salt bath method. The coating thickness layers were measured by SEM. The different phases formed on the samples, due to different amounts of carbon in treating salt bath, were determined by X-ray diffraction. It was found that in molten borax salt with high carbon content (high carbon ferro chromium) very few amount of chromium diffused into the plain carbon steel. The thickness of the diffused chromium layer in low and high carbon content ferro chromium in molten borax, is around 32±8 µm and 6.8±1.2 µm, respectively. A number of tests were conducted to address this effect.
Characterization of Pt-Doped WO3 Nanoparticles Synthesized by Flame Spray Pyrolysis
Authors: Samerjai Thanittha , Tamaekong Nittaya , Phanichphant Sukon
Published: May 2012

Undoped WO3 and WO3 nanoparticles doped with 0.251.0 wt.% Pt were successfully produced in a single step by flame spray pyrolysis (FSP) [. Tungsten (VI) ethoxide 5% w/v in ethanol 99.8% and platinum (II) acetylacetonate were used as W and Pt precursors respectively dissolved in ethanol. The undoped WO3 and Pt-doped WO3 nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The BET surface area (SSABET) of the nanoparticles was measured by nitrogen adsorption. From BET measurement, SSABET increased and dBET decreased with increasing Pt concentration from 0 to 1.0 wt.%. The morphology and accurate size of the primary particles were further investigated by high-resolution transmission electron microscopy (HRTEM). The crystallite size of undoped WO3 spherical was found to be ranging from 520 nm and the crystallite sizes of 0.251.0 wt.% Pt-doped WO3 spherical particles were found to be in the range of 520 nm.
Prediction of Weld Bead Parameters, Transient Temperature Distribution & HAZ Width of Submerged Arc Welded Structural Steel Plates
Authors: Ghosh Aniruddha , Chattopadhyaya Somnath , Singh N.K.
Published: May 2012

In submerged arc welding process, concept on temperature distribution is essential in order to control HAZ dimensions and get the required bead size and quality. In this paper, an analytical solution for moving heat source with Gaussian distribution of inside volume of central conicoidal shape is derived. Heat transfer in welded plates during welding is assumed to be conductive heat transfer of a semi infinite body. With the help of this analytical solution, transient temperature distribution, HAZ width, weld bead dimensions are estimated. Good agreements between predicted and experimental values are achieved.
CFD Simulation of Coaxial Jet Mixer Using RANS Turbulent Models
Authors: Ku Shaari Ku Zilati , Laziz Afiq Mohd , Heinen Kerstin , Awang Mokhtar , Sufian Suriati , Shuhaimi Mahadzir
Published: May 2012

The Reynolds Averaged Navier Stokes Equation (RANS) model was used to describe the turbulent flow in a coaxial jet mixer. The effects of turbulent models on the turbulent flow is investigated to help the engineers and researchers in deciding the selection of turbulent model need to be used in order to save the simulation time and to predict the best suitable model to be used. Good agreement of the CFD prediction with the experimental data in certain locations was obtained with species transport and velocity profiled, where dependence of turbulent models and grid sizes were discussed in detail. The results show that, the need of grid study is crucial to obtain reliable results with optimum consumption of computer power. SST and Launder Gibson RSTM models give results superior to the other models, each of which has its own area of capability. Launder Gibson RSTM is good in predicting the flow with recirculation and vortices, while SST is good for the flow with less recirculation and high velocity. The overall results show that RANS model is capable in predicting the area of mixing and the velocity profile correctly in certain locations but not in reproducing the vortices structure in the pipe and nozzle.
Rheology Assessment of PSf/ NMP Solution and its Influence on Membrane Structure
Authors: Anadão Priscila , Montes Rafael Rezende , de Santis Henrique Souza , Wiebeck Hélio
Published: May 2012

Asymmetric polysulfone membranes were prepared by wet-phase inversion method from casting solutions consisting of PSf/NMP and water as non-solvent. The effects of polymer concentration and molar mass were investigated by rheological studies. Moreover, membranes were characterized by scanning electron microscope (SEM). It was found that polymer solutions containing between 22 and 25 wt% PSf/NMP originated microfiltration membranes. The use of a higher mass molar polysulfone has been shown to reduce diameter pore and to maintain morphology. All the results were interrelated into a discussion of the skin formation of asymmetric membranes.
Solid Skin Characterization of PMMA/MAM Foams Fabricated by Gas Dissolution Foaming over a Range of Pressures
Authors: Pinto Javier , Pardo Samuel , Solórzano E. , Rodríguez-Pérez Miguel A. , Dumon M. , de Saja Jose A.
Published: May 2012

A new model for solid skin formation on submicrocellular foams based on PMMA is presented. Structural foams has been produced by the solid state foaming technique using as precursor material a blend of poly (methyl methacrylate) PMMA and a triblock copolymer [poly (methyl methacrylate)-block poly (butyl acrylate)-block poly (methyl methacrylate), MA.
An analysis on the skin thickness and densification has been carried based on x-ray high resolution radiography. The obtained results have been related to the fabrication parameters, i.e. MAM content of the blend and foaming pressure, and provide us a new vision about the processes that control the formation of a solid unfoamed, or partially unfoamed, skin in these materials.
Measurement of the Molecular Mass Dependence of the Mass Diffusion Coefficient in Protein Aqueous Solutions
Authors: Torres Juan F. , Komiya Atsuki , Okajima Junnosuke , Maruyama Shigenao
Published: May 2012

This paper reports the measurement of the binary mass diffusion coefficient for proteins with a wide range of molecular size. The diffusion coefficient is obtained by conducting diffusion experiments in the dilute region. Transient concentration profiles were measured by a phase shifting interferometer and subsequently compared with a numerical calculation based on Ficks law to determine the diffusion coefficient. Distilled water was used as solvent in free diffusion experiments conducted at T = (25 ± 1.0)°C. The method was validated by measuring the diffusion coefficient of aqueous NaCl, Sucrose, and BSA, which values have been extensively reported in the literature. The values of the diffusion coefficient for seven proteins: aprotinin (6.5 kDa), α-lactalbumin (14.2 kDa), lysozyme (14.3 kDa), trypsin inhibitor (20.1 kDa), ovalbumin (44.2 kDa), bovine serum albumin (66.7 kDa), and phosphorylase b (97.2 kDa), were determined in the dilute region of 0-3 mg/ml. The results are compared with the Stokes-Einstein equation. The influence of the molecular structure and pH on the diffusion coefficient is discussed.
Diffusivity of Hydrogen in ZnO Single Crystal
Authors: Čížek Jakub , Lukáč František , Vlček Marián , Procházka Ivan , Traeger Franziska , Rogalla Detlef , Becker Hans Werner
Published: May 2012

Hydrogen diffusivity in ZnO (0001) single crystal was investigated using electrical resistometry and nuclear reaction analysis (NRA). ZnO crystals were covered with a thin Pd over-layer and electrochemically charged with hydrogen. The net concentration of hydrogen determined by NRA was found to be in a reasonable agreement with the value estimated from the transported charge using the Faradays law. The hydrogen diffusion coefficient in ZnO was estimated from in-situ electrical resistivity measurements. Moreover, NRA investigations revealed existence of a subsurface layer with very high concentration of hydrogen (up to 40 at.%). Typical surface modification observed on hydrogen loaded crystal by light microscope indicates hydrogen-induced plastic deformation realized by a slip in the c-direction. Open-volume defects introduced by hydrogen-induced plastic deformation trap diffusing hydrogen and cause an enhancement of hydrogen concentration in the deformed subsurface layer.
Crystallisation of Silicon on Reinforcement Fibres as a Consequence of Overheating of Matrix Metal during Saturation in MMC
Authors: Gawdzińska Katarzyna , Nagolska Dorota , Grabian Janusz
Published: May 2012

Metal-matrix composites for many years have been widely used as engineering material all over the world, also in Poland. It is due to good construction properties, small specific gravity, ease of product formation, also large size items, diversity of manufacturing methods, and great possibilities of changing their properties depending on the output products used [.
The authors of this study deal with metal-matrix composites made by casting. One of the methods they use in their research includes the saturation of the reinforcement structure (short disordered fibres pressed like felt, forming a profile, called preform) with metal liquid matrix under pressure.
Phenomena occurring in the production of a composite material are similar to those taking place during making casts from traditional materials (cast steel, cast iron, non-ferrous metal alloys).
This article is an overview of a problem encountered while detecting and describing defects of metal-matrix composite materials produced by saturation. It focuses on phenomena that take place during casting solidificationespecially the influence of the matrix (with different temperatures of liquid metal) on the reinforcement during its saturation and crystallisation of silicon plates on it.
Microstructure and Thermal Analysis of Mg-Al-Ca-Sr Alloys
Authors: Rzychoń Tomasz
Published: May 2012

The paper presents results of DSC and microstructural investigations of Mg-6Al-1Ca-1Sr-0.3Mn (ACJ611) and Mg-8Al-3Ca-1Sr-0.2Mn (ACJ831) magnesium alloy in as cast condition. The microstructure of this alloy consists of aluminum in magnesium solid solution and two types of eutectic: α-Mg+Al2Ca and α-Mg+Al3Mg13Sr. The liquidus temperature of ACJ611 magnesium alloy is 613°C. The eutectic reactions L α-Mg+Al2Ca and Lα-Mg+Al3Mg13Sr occurs at 510°C and 502°C temperatures, respectively. The increase of aluminum and calcium content increases the volume fraction of Al2Ca phase, decreases the liquidus temperature and slightly increases the temperature of eutectic reactions.
Effect of Thermal Contact Resistance on Alumina Molten Particle Impacting onto a Metal Substrate
Authors: Oukach S. , Pateyron Bernard , Hamdi H. , El Ganaoui M.
Published: May 2012

In this paper, a Finite Element Analysis is carried out in order to simulate the process of spreading and solidification of a micrometric molten droplet impinging onto a cold substrate. This process is a crucial key to have a good understanding of coatings obtained by means of thermal spraying. The effect of thermal contact resistance (TCR) on the droplet spreading and solidification was investigated using different values of TCR and different droplet sizes. The solidification time was found to be a linear function of the droplet diameter square. Viscous dissipation, wettability and surface tension effects are taken into account. The Level Set method was employed to explicitly track the free surface of molten droplets.
An Attempt to Apply Darcy′s Flow Law in MMC Recycling Process Analysis
Authors: Nagolska Dorota , Gawdzińska Katarzyna
Published: May 2012

To determine the possibility of carrying out the recycling process of metal-matrix composite castings with saturated reinforcement, only Dupre equation was used until now. Basing on this equation, one can determine superficial conditions in the system: liquid metal (matrix) solid reinforcement medium, favouring the process of autogenous outflow of liquid matrix from the porous reinforcement. It is however very difficult to determine the influence of the structure parameters of reinforcement preforms on examined process. Hence the need to preform analysis of process of liquid metal matrix outflow using Darcys law of flow. Application of this law allows replacing difficult to determine parameters of capillaries occurring in performs with one, quite simple to calculate parameter of permeability. It also makes possible defining the influence of temperature and time of recycling process on yield of matrix metal. To verify stated theses, study of permeability of selected reinforcement preforms and recycling of selected metal-matrix composites with saturated reinforcement was conducted. Furthermore, analysis of liquid metal matrix outflow process from studied preforms was performed, in aspect of application of Darcys law.
Characteristics and Wear Performance of Nitrided Ti6Al4V
Authors: Seahjani Fared , Çimenoğlu H.
Published: May 2012

Samples of a Ti6Al4V alloy were treated by thermochemical gas nitriding at 1120°C for 7 h. Gas nitriding provided formation of titanium nitride layer with a hardness over 1800 HV. The titanium nitride layer exhibited excellent wear resistance along with a lower coefficient of friction against alumina ball under dry sliding conditions when compared to the as-received state.
Creep Behavior of the Inconel 718 Superalloy
Authors: Sugahara Tarcila , Martinolli Karina , Reis Danieli A.P. , de Moura Neto Carlos , Couto Antônio Augusto , Neto F. Piorino , Barboza M.J.R.
Published: May 2012

A superalloy is an alloy developed for elevated temperature service, where relatively severe mechanical stressing is encountered, and where high surface stability is frequently required. High temperature deformation of Ni-base superalloys is very important since the blades and discs of aero engine turbine, because need to work at elevated temperature for an expected long period. The nickel-base alloy Inconel 718 has being investigated because it is one of the most widely used superalloys. The objective of this work was to evaluate the creep behavior of the Inconel 718 focusing on the determination of the experimental parameters related to the primary and secondary creep states. Constant load creep tests were conducted with at 650, 675 and 700°C and the range of stress was from 625 to 814 MPa to according to ASTM E139 standard. The relation between primary creep time and steady-state creep rate, obeyed the equation for both atmospherics conditions at 650, 675 and 700°C. The microstructural characterization employing the technique of scanning electron microscopy has been a valuable tool for understanding the mechanisms of creep.
Modeling Analyze from Titanium Alloy
Authors: Guimarães Nara Miranda , Reis Danieli A.P. , de Moura Neto Carlos , Coelho Gilberto Carvalho , Couto Antônio Augusto
Published: May 2012

Titanium and its alloys have been used a lot for its special and unique properties, and characteristics under different conditions [. When we want to use one of its alloys in aerospace industry, we have to assure that in these conditions the material will resist and keep its integrity [1,. We wanted to analyse a titanium based superalloy by modeling a routine and extracting information from it about the dependence between Gibbs free energy and the amount of weight from two components, titanium and aluminium, which is the second major element according to X-ray diffraction analysis. It was concluded that increasing Ti amount, or making the alloy richer on titanium, the system leads to a higher level of energy. The opposite behaviour happens with aluminium; increasing it, the energy of the system decreases which is great, once the equilibrium is obtained with lower levels of energy. Although the analysis had been done with a general database available in the software, its possible to predict how the material will be influenced under several situations in a quick and reliable method.
Evaluation of Inconel 718 Creep Behavior
Authors: Martinolli Karina , Sugahara Tarcila , Reis Danieli A.P. , de Moura Neto Carlos , Hirschmann Ana Cláudia , Couto Antônio Augusto
Published: May 2012

Superalloys are used primarily in aerospace applications. These applications require a material with high mechanical strength, good resistance to fatigue and creep, good corrosion resistance and ability to operate continuously at elevated temperatures. These alloys were developed for elevated temperature service, where relatively severe mechanical stressing is encountered, and where high surface stability is frequently required. Inconel 718 has being investigated because it is one of the most widely used superalloys. Constant load creep tests were conducted on a standard creep machine at 600 and 700°C and stress levels of 300 MPa. Sets of curves and experimental parameters for the primary, secondary and tertiary regions, as a function of stress and temperature applied were obtained. The ductility, the creep rate and lifetime was evaluated.
Lattice Boltzmann Analysis of the Heat Transfer in Cubical Enclosures
Authors: Ameziani Djamel Eddine , Benacer Rachid , Belmedani Mohamed , Boutraa Abdelkader
Published: May 2012

The purpose of this work is to study hydrodynamic and thermal characteristics of air contended into a differentially heated cubic cavity. Due to their importance in the characterization of heat transfer in this kind of configuration, the effect of some parameters is analyzed. It consists in the Rayleigh number and the aspect ratio. In order to resolve the governing equations, the Lattice-Boltzmann method coupled with finite difference method is used.
Characterization of a Hygro-Regulated Wall Base Ventilation System for Treatment of Rising Damp
Authors: Guimarães A.S. , Delgado João M.P.Q. , de Freitas V.P.
Published: May 2012

The treatment of rising damp in the walls of historical buildings is very complex, due to the thickness and heterogeneity of the walls. The techniques traditionally used for dealing with this problem (such as watertight barriers, injection of hydrofuge products, etc.) have sometimes proved ineffective, and that is why it is necessary to find a new approach.
In recent years, the Building Physics Laboratory at the Faculty of Engineering, University of Porto has been conducting experimental research on the effectiveness of the wall base ventilation system, using natural or mechanical higro-regulate systems to reduce the level of the damp area. This experimental research and the simulations that were performed, clearly show that wall base ventilation is a system with potential.
This paper presents the characterization of the hygro-regulated systems operation based on experimental studies developed in laboratory, which allowed the influence of the velocity of the air, condensation risk and the possibility of salt crystallization.
Influence of Casting Conditions and Alloy Additions on the Zn22Al2Cu Structure
Authors: Michalik Rafał , Tomaszewska A. , Woźnica H.
Published: May 2012

Zn-Al-Cu alloys are characterized by a number of beneficial properties that include good castability, good tribological properties and low energy input for forming the product. When compared to bronze, Zn-Al-Cu alloys have a lower density.
Properties of Zn-Al-Cu can be improved by the partial or total replacement of copper with silicon and rare earth element additions. In the literature there are few studies on the effect of casting conditions and modifying the chemical composition through the introduction of alloy micro-additives on the alloy structure.
The aim of this study was to determine the effect of casting conditions and silicon and rare earth element additions on the structure of Zn-22% Al-2%Cu alloy. The subjects examined were the unmodified alloy, the alloy with 1.5% Si and the alloy with 1.5% Si and rare earth elements (mich metal). Samples were cast in sand and graphite molds. The liquidus temperature for each of these examined samples was determined.
Structure examinations were carried out in samples taken from the top, center and bottom of the ingot. In order to determine the microstructure of the examined structures metallographic examinations using an optical microscope and a scanning electron microscope with energy dispersive spectroscopy (EDS) capabilities, an X-ray microscope, was performed. Quantitive analysis on specific, characteristic microzones was performed based on the EDS X-ray spectroanalysis results.
Structure and Corrosion Resistance of Cast ZnAl40Cu2 Alloy
Authors: Michalik Rafał , Woźnica H.
Published: May 2012

Zn-Al-Cu alloys are used as an alternative material for bronze, cast iron and aluminum alloys in bearings and as construction material. Advantageous results brings of their application for bearings exposed to high loads. One of the factors determining the possible applications of Zn-Al-Cu alloys is their resistance to electrochemical corrosion. In literature can be found information on the corrosion resistance of Zn-Al-Cu alloys. There have been no comprehensive studies on the influence of casting conditions and modifications of chemical composition on the structure and corrosion resistance. The purpose of the experiments was to determine the structure and corrosion resistance of cast Zn-40%Al-2%Cu alloy. The scope of the experiments included X-ray phase analysis, potentiodynamic and potentiostatic tests, surface condition examinations and alloy structure characterization both before and after corrosion. The Zn40Al2Cu alloy is characterized by a dendritic structure, consisting of solid solutions of Al, Zn-Al and Zn and the CuZn5 phase. A corrosive environment affects the structure of the subsurface zone of the Zn40Al2Cu alloy to a depth of 60 to 130 μm, where a decrease of zinc content and an increase of aluminum content are observed.
Heat-Mass Transfer and Related Microstructures in TiAl-Based Alloys Directionally Solidifying in the Earth Gravity and Microgravity
Authors: Kartavykh A.V. , Ginkin V.P. , Ganina S. , Rex S. , Hecht Ulrike , Voss D.
Published: May 2012

The first results are presented of ESA MAXUS 8 sounding rocket benchmark experiment on γ-TiAl (Nb,B) intermetallics solidification, that was a part of the IMPRESS EU FP6 project. Having the aim to investigate the columnar and equiaxed primary microstructures formation at diffusion controlled melt growth, an experiment was designed applying the power-down directional solidification technique with fixing quench in automatic spaceborne furnace module TEM03-5M. Two related alloys were tested: one inoculated with boron grain refiner Ti-44Al-7.5Nb-2.7B (at.%); and the other Ti-45.5Al-8Nb (at.%) without grain refinement. The series of terrestrial reference processes has been performed accordingly in counter-gravity solidification direction. The numerical studies of heat-mass transfer, melt hydrodynamics and temporal solidification dynamics of these alloys have been implemented under the earth-and zero-gravity approximations using the GIGAN software package (IPPE). The comparison is performed of numerical model findings with the real microstructure and composition of samples, whose analyses were carried out by backscattered scanning electron microscopy (SEM) and X-ray microprobe (EDX) techniques. The convection-induced peritectic macrosegregation effect appearance and development in ground-based reference ingots is analytically observed and numerically studied. The achieved microstructure formation in space benchmarks is discussed.
Study of Phase Transformation in Alloys of the Al-Fe System
Authors: Jabłońska Magdalena , Mikuśkiewicz Marta , Śmiglewicz Anna , Bernstock-Kopaczyńska E.
Published: May 2012

In this paper, phase transformation in alloys of the Al-Fe and Al-Fe-Cr systems was investigated. The alloys were prepared by melting and gravity casting. The studies of phase transformation were carried out on samples after casting and annealing, using the differential thermal analysis (DTA) and dilatometric method. The knowledge on the phase transformations in these alloys including the information about order-disorder transition is very important from the point of view of obtained mechanical and physical properties of alloys of the Al-Fe system. These results are an important contribution in development of knowledge on iron aluminides. In the article, temperatures of phase transformations connected with a change in order type and transition into disordered solid solution were defined. Conformity of the recorded DTA results and dilatometric analysis was achieved.
Evaluation of the System Free Energy in FG-HAZ of Mod.9Cr-1Mo Steel for Nuclear Power Plants
Authors: Iwata Mitsunao , Sugiyama Yuichi , Murata Yoshinori , Takaya Shigeru
Published: May 2012

In heat resistant materials, the microstructural change occurs due to atomic diffusion and it affects directly to their mechanical properties. It is known that the state of this microstructural change can be represented by the system free energy, and therefore evaluation of this free energy is useful for the damage analysis of the materials. In this study, change in the system free energy of FG-HAZ in 9Cr heat resistant ferritic steels was estimated with creep time on the basis of a series of experiments. As a result, it was found that system free energy decreased with creep time and the decreasing rate was accelerated by applied stress. The change in the system free energy expressed as a function of applied stress makes it possible for, the microstructural state of the steel to predict an arbitrary creep condition.
Development of Nonlinear Analytical Models for the Study of Heat/Mass Transfer Properties in the Drying of Porous Type Fabric
Authors: Ip Ralph W.L. , Wan Elvis Iok Cheong
Published: May 2012

Designing a drying process for porous type fabrics using traditional linear heat transfer models may be inefficiency because the drying characteristics in the process are usually nonlinear. Using nonlinear approaches to describe the heat/mass flow could be better for many industrial application cases. The paper as presented here is a study for an analytical model using differential form nonlinear equations to describe heat transfer and moisture diffusion process using air as the processing medium. Experimental findings were used to evaluate the performance of the studied model. Relationships between the model parameters and fabric physical properties were determined for further used in the design of drying equipment.
Comparison of Two Models for Simulation of Binary Alloy Solidification
Authors: Ganina S. , Ginkin V.P. , Budenkova Olga , Saadi B. , Hachani L. , Fautrelle Yves
Published: May 2012

The results of running a quasi two-dimensional experimental benchmark for horizontal directional solidification of binary Sn-3 wt.%Pb alloy in a rectangular region are presented. The computation was performed using the GIGAN software and two models to simulate the mushy zone were compared, namely, the one based on the equilibrium approach and the non-equilibrium one.
The Effect of Hydrogen on Pitting Corrosion of Superaustenitic and Austenitic-Ferritic Stainless Steels
Authors: Michalska Joanna
Published: May 2012

Hydrogen entering into steel affects its electrochemical properties and may enhance the susceptibility to environmental degradation. The present work has been aimed at further clarifying the effect of hydrogenation on the corrosion behaviour and passivity of highly-alloyed stainless steels. The results were discussed by taking into account hydrogen charged samples and without hydrogen. The corrosion resistance to pitting was qualified with the cyclic polarization curves. The conclusion is that hydrogen may deteriorated the passive film stability and corrosion resistance to pitting of highly-alloyed stainless steel. Furthermore, the presence of hydrogen in passive films increases corrosion current density, decreasing the potential of the film breakdown and repassivation potential. It was also found that the degree of susceptibility to hydrogen-enhanced pitting corrosion was dependent on the type of steel.
Analysis of Stress Induced Voiding Using by Finite Element Analysis Coupled with Finite Difference Analysis
Authors: Shigeyama Haruhisa , Yokobori Jr. A. Toshimitsu , Ohmi Toshihito , Nemoto Takenao
Published: May 2012

In this paper, the vacancy migration in Cu interconnect of large scale integration caused by stress induced voiding was calculated using the α multiplication method. Then, the effect of weight coefficient, α, on stress induced vacancy diffusion analysis was investigated and the validity of the α multiplication method was verified. Furthermore, the method of the vacancy diffusion analysis coupled with thermal stress analysis which can consider the history of thermal stress due to temperature changes was proposed. The results of the vacancy diffusion analysis coupled with the thermal stress analysis were compared with the analytical results of the vacancy migration without the effect of history of thermal stress. As a result, the maximum site of vacancy accumulation was found to be qualitatively in good agreement between them. However, the quantitative value of maximum vacancy concentration obtained by the vacancy diffusion analysis coupled with thermal stress analysis was found to be much higher and the vacancy distribution is found to be much more localized.
Exergetic Analyses of a Particular Absorption Cooling System
Authors: Bouaziz Nahla , Lounissi D. , Kairouani Lakdar , El Ganaoui M.
Published: May 2012

The objective of this work is to present an exergy analysis of a novel absorption configuration using water-ammonia as working fluid. The proposed configuration operates at three pressure levels. The absorber is at an intermediate pressure (Pint). A thermodynamic model based on the mass energy and exergy balances is developed for this purpose. The parameters analyzed are the refrigeration systems performance (COP), the exergy efficiency, the global exergy destruction in the system, the exergy destruction and the irreversibility in different components. The effects of generator, absorber, condenser and evaporator on the performance of the system are examined. Numerical results highlight the great importance of the intermediate pressure on the performance of the system and specially on reducing the operating generator temperature. Consequently, the intermediate pressure is directly responsible on the adaptability of the proposed cooling absorption cycle to low enthalpy sources.
Effect of Frequency on Hydrocarbon (HC) Detection Using 3D Finite Integral Modeling
Authors: Daud Hanita , Niaz Akhtar Majid , Yahya Noorhana , Nasir Nadeem , Soleimani Hasan
Published: May 2012

Detection of hydrocarbon in sea bed logging (SBL) is still a very challenging task for deep target reservoirs. The response of electromagnetic (EM) field from marine environment is very low and it is very difficult to predict deep target reservoirs below 2500 m from the sea floor. Straight antennas at 0.125 Hz and 0.0625 Hz are used for the detection of deep target hydrocarbon reservoirs below the seafloor. The finite integration method (FIM) is applied on 3D geological seabed models. The proposed area of the seabed model (16 km ×16 km) was simulated by using CST (computer simulation technology) EM studio. The comparison of different frequencies for different target depths was done in our proposed model. Total electric and magnetic fields were applied instead of scattered electric and magnetic fields, due to its accurate and precise measurements of resistivity contrast at the target depth up to 3000 m. From the results, it was observed that straight antenna at 0.0625 Hz shows 50.11% resistivity contrast at target depth of 1000 m whereas straight antenna at 0.125 Hz showed 42.30% resistivity contrast at the same target depth for the E-field. It was found that the E-field response decreased as the target depth increased gradually by 500 m from 1000 m to 3000 m at different values of frequencies with constant current (1250 A). It was also investigated that at frequency of 0.0625 Hz, straight antenna gave 7.10% better delineation of hydrocarbon at 3000 m target depth. It was speculated that an antenna at 0.0625 Hz may be able to detect hydrocarbon reservoirs at 4000 m target depth below the seafloor. This EM antenna may open a new frontier for oil and gas industry for the detection of deep target hydrocarbon reservoirs below the seafloor.
Drying Kinetics of External Thermal Insulation Composite Systems (ETICS)
Authors: Barreira E. , Delgado João M.P.Q. , Ramos N.M.M. , de Freitas V.P.
Published: May 2012

Moisture is one of the most deteriorating factors of buildings. The moisture content depends on hygroscopic equilibrium between buildings materials and environment, which is determined by the drying and wetting rate of masonry. So, the moisture content is not only determined by the water that is absorbed by the material, but also by the amount of water that is evaporated under favourable conditions, which is described by the drying process.
In this work we analyse the drying kinetics of External Thermal Insulation Composite Systems (ETICS) using a first-order and a second-order drying kinetic models to describe mass transfer phenomenon. The results show that the second-order kinetic models described well the drying process studied. The application of kinetics models to the experimental results was explored and several parameters were retrieved. A proposal for the use of these parameters is presented and its practical use is discussed.
Structure, Thermal Stability and Properties of Grain Boundaries of Submicrocrystalline Mo Obtained by Severe Plastic Deformation
Authors: Popov Vladimir V. , Grabovetskaya Galina P. , Sergeev A.V. , Mishin I.P.
Published: May 2012

The structure of submicrocrystalline Mo, obtained by high pressure torsion, its thermal stability and the state of grain boundaries have been studied by transmission electron microscopy and emission Mössbauer spectroscopy.
Isotopic Exchange of Gaseous Oxygen with Mechanoactivated Manganese Oxides
Authors: Fishman Anatoly Yakovlevich , Kurennykh Tatiana Eugenievna , Vykhodets Vladimir Borisovich , Vykhodets V.B.
Published: May 2012

sotope exchange of oxygen 18О2 with oxides Mn2O3 and Mn3O4 was investigated in the temperature range of 300700°C. It was established that the content of the isotope O18 in mechanically activated powders was noticeably higher than in the initial ones. Already at relatively low annealing temperatures isotope exchange leads to nearly the maximum possible under the given conditions replacement of atoms 16O to 18O. The isotope exchange parameters connected with the processes at the boundaries of the particles of mechanoactivated powder and within their volume were determined.
Hydrogen Mobility in the Non-Martensitically Transforming Shape Memory Alloy Ni52Ti48
Authors: Mazzolai Giovanni
Published: May 2012

Hydrogen mobility has been studied at high temperature by absorption experiments in the Ni52Ti48 alloy, which does not transform martensitically but rather behaves like a so-called strain glass. The results obtained have been compared with those deduced from an anelastic relaxation occurring in this alloy below the strain-glass transition temperatures. An accurate analysis of the anelastic data has confirmed the conclusion that the relaxation is related to H rather than to the glass transition. Its relaxation time obeyed a Voogel-Fulcher type of temperature dependence. Combining absorption and anelastic results, the H diffusion coefficient in the B2 lattice structure of this alloy could be studied from 1200 K down to 170 K. The agreement between the absorption and mechanical spectroscopy data was satisfactory. The activation energy (0.33 eV) deduced from a Vogel-Fulcher representation of the H diffusion coefficient D was sensibly lower than earlier determinations (0.44-0.50 eV) from Arrhenius plots. The high temperature data of Ni52Ti48 alloy, compared with the ones available in the literature for other NiTi SMA in their B2 structure, show a substantial independence of D on the alloy composition.
Slow Crystallization of Al-Sc Alloys: Growth of Spherical Intermetallic Particles
Authors: Shubin A.B. , Popova E. A. , Shunyaev K. Y. , Pastukhov E.A.
Published: May 2012

The solidification of binary Al-Sc melts containing small amounts of scandium (< 2 wt.%) have been investigated. We studied concentration profiles in long Al-Sc as cast ingots formed by slow cooling of the liquid alloys. It was found that minor addition of transition metals like Ti can lead to the formation of large (about 10-20 μm) spherical intermetallic particles (Al3Sc containing some amount of isomorphic Ti). These sphere-like particles are forming during the crystallization of liquid solution of Sc in Al (before the precipitation on nanosize spherical particles from the solid solutions). The results of SEM and EDX investigations of these alloys are also presented in this paper.
Estimation of Li-Ion Diffusion Coefficients in C60 Coated Si Thin Film Anodes Using Electrochemical Techniques
Authors: Arie Arenst Andreas , Lee Joong Kee
Published: May 2012

C60 coated Si thin films were prepared sequentially by a plasma enhanced chemical vapor deposition and a plasma assisted thermal evaporation technique. The films were then utilized as anode materials for lithium ion batteries. The diffusion coefficients of Li-ions in the film electrodes were then estimated by typical electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. The diffusion coefficients determined by both methods were found to be consistent each other. The diffusion coefficient of coated samples was obviously higher than that of bare silicon thin films, indicated that the kinetic properties of lithium ion transport in silicon film electrodes were enhanced by the C60 film coating on its surface.
Synthesis and Characterization of the Gold-SiO2 Core-Shell Nanoparticle on the X-Nanozeoliate Used for Immobilization of the Alkaline Protease Enzyme
Authors: Farhadyar Nazanin , Seyed Sadjadi Mirabdullah
Published: May 2012

Immobilized enzymes enhance process robustness, allow longer duration of activity of enzymes, and re-use of the same enzymes in multiple cycles. Enzymes can be operated in the liquid form or immobilized on various supports. In this work, we prepared gold nanoparticle core-shell structure by assembling of the gold nanoparticles on the surface of amine-functionalized x-type zeolite and then used them for immobilization of the alkaline protease. Characterization of these assembled systems were carried out by UVvisible, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive analysis of X-ray (EDAX). Biocatalytic activity of the alkaline protease in this bioconjugate system was examined and showed an increase in comparing with the free enzyme in solution.
The Kinetic Monte Carlo Simulations of the Self-Diffusivity in Zeolites
Authors: Tarasenko Alexander , Jastrabik Lubomir
Published: May 2012

The diffusion of guest molecules in zeolites is investigated in the framework of a onedimensionallattice-gas model with two non-equivalent sites. The concentration dependenciesof the tracer and center-of-mass diffusion coefficients are calculated for some representative valuesof the lateral interaction between the guest molecules. Using simple ideas about moleculesdiffusion we propose analytical expressions for the diffusion coefficients. We compare the theoreticaldependencies with the numerical data obtained by the kinetic Monte Carlo simulations.A very good coincidence of the data obtained by the two quite independent different methodscorroborates strongly the validity of the proposed approach.
A Hierarchical Approach to Purify and Functionalize Pristine Carbon Nanotubes
Authors: Mansoor Muhammad
Published: May 2012

A step-by-step, hierarchical approach is explored in the present work to purify and functionalize carbon nanotubes synthesized by chemical vapor deposition. Attempts are made to purify and functionalize CNTs without extinguishing their aspect ratios. The carbon impurities are removed by thermal oxidation, whilst the unprotected metallic catalyst particles are eliminated by wet oxidation, subsequently; CNT bundles are de-roped by surfactant assisted sonication. Finally, protected metallic catalyst particles are removed and functional groups (hydroxyl and carboxyl) are attached by acid treatment and wet oxidation, respectively. The derivate CNTs are characterized using zeta potential measurements, TGA, XRD, FTIR and SEM. The characterization showed that in optimum experimental conditions the catalytic particles are removed upto 80%, the carbon impurities are eliminated upto 95% and chemical functionalities of hydroxyl and carboxyl is occurred with noticeable de-roping of the CNT bundles.
Synthesis of Single and Multi Walled Carbon Nanotubes by Improved Arc Discharge Method
Authors: Sami-Ullah S. , Waqar S.M.H. , Hussain F. , Ali A.
Published: May 2012

This paper presents the development of a laboratory scale setup for the production of CNTs by arc discharge process in an argon gas environment. The main problem with the existing lab scale production setups is the cleaning of the chamber and this problem is resolved in presented work by placing a circular metal sheet inside the chamber, which is removed after the synthesis, thus allowing easy cleaning and recovery of the produced CNTs. The most noteworthy feature of the presented setup is its low cost, hence offering for the first time the synthesis of economical CNTs on small scale. In addition to offering better control over operating conditions and hence the quality of CNTs, another unique feature of the developed setup is its capability to synthesize SWCNTs and MWCNTs with versatile range of diameters. Significant quantity of CNTs using the developed setup were produced and characterized by using Scanning Electron microscope (SEM) and few results are reported.
Effect of Substrate Temperature on the Structural and Electrical Properties of MBE Grown ZnO
Authors: Asghar M. , Mahmood Khalid , Hasan M.A.
Published: May 2012

We have grown a plenty of samples to investigate the effect of substrate temperature on the structural and electrical properties of grown films. X-ray diffraction analysis confirmed the hexagonal structure of ZnO with preferred c-orientation. As we increased the substrate temperature from 74 °C to 500 °C, the microstructure of films improved. The position of (002) peak remained constant but its intensity increased remarkably with increasing substrate temperature. The FWHM of films decreased and crystalline size increased with substrate temperature. We also observed strong dependence of electrical properties on the substrate temperature. The thickness, resistivity and growth rate are directly proportional to the substrate temperature. The possible reason of higher resistivity of thick films is that with improved microstructure, ZnO films have low density of interstitials defects, which acted as free carriers and therefore results in the increased of resistivity.