bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Stress Distribution at the Interface Metal-Oxide: Numerical and Theoretical Considerations
Authors: Garruchet Sébastien , Hasnaoui A. , Politano Olivier , Montesin Tony , Salazar J. Marcos , Bertrand G. , Sabar H.
Published: March 2009

In this paper we give a brief presentation of the approaches we have recently developed on the oxidation of metals. Firstly, we present an analytical model based on non-equilibrium thermodynamics to describe the reaction kinetics present during the oxidation of a metal. Secondly, we present the molecular dynamics results obtained with a code specially tailored to study the oxidation and growth of an oxide film of aluminium. Our simulations present an excellent agreement with experimental results.
Kinetic Constraints in Diffusion
Authors: Danielewski Marek , Wakihara M.
Published: March 2009

In the presence of strong external fields and steep gradients the flux formulae are not linear. The relation between the flux and the diffusion coefficient must be modified. The different flux-limited theories are presented. The flux formulae for solid systems far from equilibrium are derived and different forms of phenomenological flux limiters are discussed. It is shown that in order to accurately compute diffusion flow that is generated by strong force fields and/or discontinuities, the flux-limited diffusion must be considered. The flux limiters improve the spatial accuracy and allow to avoid baseless oscillations in the solutions.
Software for Simulation of Oxidation Processes
Authors: Li Hua Long , Lin Jianlong , Szpunar Jerzy A.
Published: March 2009

A methodology for discrete simulation has been developed that incorporates many
structural characteristics of polycrystalline material properties, such as: texture, grain boundaries, microstructure, phase composition, chemical composition, stored energy, and residual stresses. The computer models that have been developed to study oxidation processes are based on a quantitative description of the oxide and substrate structure. That description allows for the simulation of the transport of metal and oxygen ions along interfaces and bulk portions of material and the formation of oxide structure. The proposed model can help researchers and engineers to understand the physical mechanism of oxidation in order to predict material behavior and optimize material processing and properties. In this paper, the results on the simulation of the oxidation process are presented on different
substrates of Zr-Nb alloys, which are used for the manufacturing the pressure tubes used in the CANDU nuclear reactors. The effects of substrate texture, microstructure, grain boundaries, and beta phase distribution on oxidation kinetics and hydrogen permeation are demonstrated.
Sedimentation of Substitutional Solute Atoms in Condensed Matter: New Type of Diffusion
Authors: Mashimo Tsutomu
Published: March 2009

Ultra-strong gravitational field (Mega-gravity field) causes the sedimentation of even atoms (diffusion), and is expected to create a nonequilibrium crystal-chemical state in multi-component condensed matter. However, the materials science research under mega-gravity field has now remained as an unexploited field, while the sedimentation of molecules or polymer had been used in biochemistory. We presented a self-consistent diffusion equation for sedimentation of atoms in condensed matter. Next, we developed an ultracentrifuge apparatus to
generate strong acceleration field of over 1 million (1x106) g at temperature range up to 〜300 °C, and, recently, succeeded in realization of the sedimentation of substitutional solute atoms in some alloys of Bi-Sb, In-Pb, Bi-Pb systems, etc. The diffusion coefficients in sedimentation on Bi-Sb alloy were estimated to be much greater than those at normal conditions by a factor of >20. It is suggested that the sedimentation of substitutional atoms in solids or liquids can be explained in a
new type of diffusion, where the diffusion mechanism for substitutional solute atoms was yet unknown. In this article, the recent progress in the investigation of sedimentation of atoms under mega-gravity field is reviewed, and the diffusion mechanism is discussed. The application of the mega-gravity field is also discussed.
Studies on Electroless Coatings
Authors: Agarwala Ramesh Chandra
Published: March 2009

Since the introduction of Electroless (EL) coating in 1946 by Brenner and Riddle, the process has been the subject of steady growth. It is one of the most elegant methods available for the production of protective coatings on surface. The technique involves the autocatalytic reduction, at the substrate/solution interface, of cations released from suitable chemical reducing agents with in the EL bath. EL coating technique is simple one, as can be manifested just by controlling pH and temperature of the coating bath. Such coatings are reported to provide excellent physical and mechanical properties. The nickel, silver and copper based alloy and composite EL coatings are being studied at Indian Institute of Technology Roorkee since 1985 and this paper deals with the gist of the same. The structural behavior of Ni-P coatings for different phosphorus contents has been extensively studied. Transmission electron microscopy (TEM) and magnetic movement studies have been used as tools for structural and kinetic studies, respectively. Submicron
size coating islands and their transformations have been deduced. The metallography studies using hot stage within TEM to follow the phase transformations occurring at various temperatures have been studied for Ni-B, EL coatings. As a forward step towards composite coatings, Ni-P-C, Ni-P-Al2O3, Ni-P-ZrO2 etc. have been developed by co-deposition techniques. Ag-graphite composite coatings produced by EL technique exhibits ~5 times higher wear
resistance and ~ 2 times better corrosion resistance apart from being a good electrical conductor. The tribological behavior of EL Ni-P-X and Ni-P coatings on steel and aluminium substrates in different conditions i.e., as-coated, heat treated at various temperatures at different extents of time with different normal loads, have been studied in terms of dry sliding friction and wear against counter face of case hardened steel. In Ni-P-X nanocoatings (X= ZrO2-Al2O3-Al3Zr), X has been produced in-situ and are composed of nano-sized particles. Such coating could be
produced uniformly on carbon fibre of 7µ diameter. Ni-P and Cu are also coated successfully on graphite/ oxide powders of ~ 120µ sizes. Micro-thickness coatings are paving ways to nanocoatings. These are the coatings in which either the thickness of the coating is in nano level or the second phase, that dispersed in the coating matrix is of nano-size. Ni-P-Ferrite nano coatings with thickness less than ~0.1mm thick, is found to exhibit about 20db of absorption of microwave in the rage of 12-18 GHz which can be exploited for radar applications. Here the nano-sized ferrite particles are co-deposited along with the Ni-P EL coatings.
Atomistic Simulation of Pipe Diffusion in AlCu Alloys
Authors: Jannot E. , Mohles Volker , Gottstein Günter , Thijsse B.
Published: March 2009

Activation energies for solute diffusion along dislocations are difficult to measure experimentally. The aim of this work is to provide insight into pipe diffusion with the help of atomistic simulations. The distribution of vacancy formation energy and the activation energy for copper migration are determined in the core of an edge dislocation in aluminum. The Dimer method is used to find activation energies for vacancy migration. The activated region around the dislocation where a very high diffusivity is observed and the activation energy for copper diffusion associated with this region are interpreted with regard to the contribution of the dislocation and the contribution of the alloying.
Pioneers and Landmarks of Diffusion
Authors: Mehrer Helmut
Published: March 2009

The science of diffusion had its beginnings in the 19th century, although the blacksmiths and metal artisans of antiquity already used diffusion phenomena to make such objects as iron swords and gilded bronze wares. Diffusion as a scientific discipline is based on several corner stones. The most important ones are: (i) The continuum theory of diffusion originated from the work of the German physiologist Adolf Fick, who was inspired by elegant experiments on diffusion in gases and of salt in water performed by the Scotsman Thomas Graham. (ii) The Brownian motion, observed for the first time by the British botanist Robert Brown, was interpreted decades later by Albert Einstein and almost at the same time by the Polish physicist Marian Smoluchowski. Their theory related the mean square displacement of atoms to the diffusion coefficient. This provided the statistical cornerstone of diffusion and bridged the gap between mechanics and thermodynamics. The Einstein-Smoluchowski relation was verified in tedious experiments by the French Nobel laureate Jean Baptiste Perrin and his coworkers. (iii) The atomistics of solid-state diffusion had to wait for the birthday of solid-state physics heralded by the experiments of the German Nobel laureate Max von Laue. Equally important was the perception of the Russian and German scientists Jakov Frenkel and Walter Schottky, reinforced by the experiments of the American metallurgist Ernest Kirkendall, that point defects play an important role for properties of crystalline substances, most notably for those controlling diffusion and the many properties that stem from it. This paper is not meant as systematic history of diffusion. It is devoted to some major landmarks and eminent pioneers of diffusion including also people from recent decades until today.
Diffusion of I Group Metals in Porous Silicon
Authors: Dzhafarov T.D , Aydin S. , Oren D.
Published: March 2009

Porous silicon (PS) layers with porosity of 60% on n-type (111) Si substrates were
prepared by anodic etching under the white illumination. Metal (Cu, Ag or Au)/PS/Si and metal
(Cu, Ag or Au)/Si structures have been fabricated by evaporation of thin metal film onto the PS or
Si surface, respectively. The diffusion annealing of structures was carried out in air at 100-250oC.
Examination of Cu, Ag and Au concentration distribution in PS layer and monocrystalline Si
substrate was performed by successive removal of thin layers from sample and measuring the
energy dispersive X-ray fluorescence (EDXRF) intensity of CuKα1, AgKα1 and AuLβ1 peak. The
effective diffusion coefficients for investigated metals along PS surfaces decrease in series Cu, Ag
and Au and temperature dependences are described as D(Cu)=7.8 exp(-0.62eV/kT),
D(Ag)=4.2x10 exp(-0.72eV/kT) and D(Au)=1.2x102 exp(-0.81eV/kT). Diffusion coefficients of Cu,
Ag and Au along PS surfaces are larger (by a factor of 104-105) than those into monocrystalline Si.
The diffusion mechanism of Cu, Ag and Au along PS surfaces is discussed and data on influence of
diffusion of these metals on humidity-sensitive characteristics of metal(Cu, Ag or Au)/PS Schottky
type gas sensors is also presented. Diffusion of metals of I group in PS is accompanied by increase
of humidity-sensitivity of metal/PS structures by a factor of 1.2-1.4.
Interdiffusion in Fe/Pt Multilayer Thin Films
Authors: O Se Young , Nguyen Dan Phuong , Lee Chan Gyu , Koo Bon Heun , Lee Byeong Seon , Shimozaki Toshitada , Okino Takahisa
Published: March 2009

Interdiffusion in Fe/Pt multilayer thin films has been studied. [Fe(1nm)/Pt(1.5nm)]20
multilayers were prepared by DC magnetron sputtering technique and subsequently annealed at
temperatures of 543 - 633K in vacuum lower than 10-6 torr. X-ray diffraction (XRD) studies on
these multilayer systems revealed the interdiffusion coefficients from slope of the best straight line
fit of first peak intensity versus annealing time. The temperature dependence of interdiffusion in the
range of 543 - 633K can be described by D=4.98×10-24 exp (0.88eV/kT) m2S-1. The coercivity,
measured by Vibrating Sample Magnetometer, of the multilayer with annealing time at 603K
increased, which is believed to the increase of surface roughness by interdiffusion at the interfaces
of Fe and Pt multilayers, enhancement of composition gradient; and/or formation of Fe-Pt reaction
phase at the interface of Fe and Pt.
Mass Transfer Analysis during Osmotic Dehydration of Pumpkin Fruits Using Binary and Ternary Aqueous Solutions of Sucrose and Sodium Chloride
Authors: Mayor Luis , Moreira Ramón , Chenlo Francisco , Sereno Alberto M.
Published: March 2009

Osmotic dehydration experiments of pumpkin with binary aqueous solutions of sucrose,
sodium chloride and ternary solutions with both solutes at 298 K were carried out. Weight
reduction, water loss and solute acquisition kinetics were determined. Experimental data were fitted
employing a diffusional model considering samples as spheres and the external resistance to the
mass transfer negligible. The model gave as parameter of fitting an effective diffusion coefficient
for each component transferred (water, sucrose and sodium chloride) for each experimental
condition assayed. Correlations between the effective diffusivity and solute concentration were
established for binary and ternary systems.
Diffusion and Interaction of W and Re in Fe-Cr Alloys
Authors: Murata Yoshinori , Kunieda Tomonori , Yamashita Kouji , Koyama Toshiyuki , Effendi Effendi , Morinaga Masahiko
Published: March 2009

The diffusivity of refractory elements in heat resistant steels is crucial for the basic
understanding of the microstructural stability during creep. The purposes of this study are to
estimate the diffusivity in Fe-Cr alloys as a base alloy for the bcc matrix phase in high Cr ferritic
steels and also to investigate the alloying effect of Re on the W diffusivity in them. Fe-15Cr and
Fe-20Cr binary alloys, Fe-15Cr-5Re, Fe-15Cr-5W, Fe-20Cr-5Re ternary alloys [mol%] were used in
this study. On the basis of the modified ternary Boltzmann-Matano method, the interdiffusion
coefficients were obtained in Fe-Cr-Re ternary system. The apparent interdiffusion coefficient for
the Re-doped Fe-Cr-W alloy was about one fifth of that for the Re-free alloy. It is concluded that the
existence of Re retarded significantly the W diffusion in Fe-15mol%Cr based alloy. This is probably
the main reason why a small amount of Re addition suppress the microstructural evolution of W
containing high Cr ferritic steels.
A Sulfur Diffusion Investigation in Metal and Oxide Phases
Authors: Radune Maya , Ophir D. , Lugovskoy Alex , Zinigrad Michael , Eliezer Dan
Published: March 2009

The purpose of the present work is to investigate the mutual interaction between the
melted metal and oxide phases with a small amount of sulfur. In this research, the following phases
took part: metallic phase of Fe – C – S and slag CaO–Al2O3 –MgO–S. The mathematical model of
sulfur diffusion in the metal and oxide is employed. The experiment was carried out at the
temperature of 1773K. The result of the calculation is in qualitative agreement with the experiment.
The proposed approach can be applied to the investigations of diffusion processes in molten metal
and slag phases.
Interaction between Stress and Diffusion in Polymers
Authors: Derrien Katell , Gilormini Pierre
Published: March 2009

When moisture uptake in a polymer is associated with swelling, it induces stresses
which interact with the entire diffusion process. This coupling is addressed in this paper, which
extends immediately to the diffusion of other fluids, like solvents. First, the generalized chemical
potential is used to analyze the effect of stresses on the moisture capacity of polymers, and a
relation is derived as a function of material parameters. Then, the interactions between stress
and diffusion before saturation is reached, are explored. Various effects are predicted on the
classical sorption test, such as an evolution of the boundary condition with time, and a sorptiondesorption
hysteresis.
Diffusion Study of Cerium and Gadolinium in Single- and Polycrystalline Yttria-Stabilized Zirconia
Authors: Bekale Vincent Menvie , Legros Corinne , Sattonnay Gael , Huntz Anne Marie , Lesage Bernard , Argirusis Christos , Jomard François
Published: March 2009

Yttria-stabilized zirconia (YSZ) ceramic is considered as an attractive matrix for nuclear
applications, such as inert matrix for the destruction of excess plutonium or good host material for
nuclear waste storage. Some actinide elements in high-level radioactive wastes can be simulated by
cerium as tetravalent actinide, and gadolinium as trivalent actinide or neutron absorber. The present
work is focused on the diffusion study of Ce and Gd in YSZ single crystal and high density
polycrystals. A thin film of Ce or Gd was deposited either by spin-coating method or by physical
vapour deposition on the surface of polished samples. The diffusion experiments were performed
from 1173 to 1673 K under air. The Ce or Gd diffusion profiles were determined by secondary ion
mass spectrometry. The experiments led to the determination of effective diffusion coefficient, Deff,
bulk and grain boundary diffusion coefficients, DB and DGB. The dependence of these diffusion
coefficients on temperature is described by means of Arrhenius equations and the diffusivity is
compared with literature.
Mössbauer Investigations of Grain-Boundary Diffusion and Segregation
Authors: Popov Vladimir V.
Published: March 2009

Possibilities of grain-boundary diffusion and segregation studies using nuclear gammaresonance
spectroscopy (NGR) are considered. It is shown that the results of the Mössbauer
investigations testify the necessity to specify the classical Fisher’s model of grain-boundary
diffusion, and a possible way of such specification is suggested. It is demonstrated that
investigation of grain boundaries using emission Mössbauer spectroscopy appreciably supplement
the information obtained from the diffusion profiles analysis. In particular, Mössbauer
investigations make it possible to evaluate directly the grain-boundary segregation factor, to
determine the grain-boundary diffusion mechanism, to estimate the rate of the diffusant pumping
from a grain boundary core into the bulk, etc.
Effect of Air Temperature on Convective Drying Assisted by High Power Ultrasound
Authors: García-Pérez J.V. , Rosselló Carmen , Cárcel J.A. , De la Fuente Susana , Mulet A.
Published: March 2009

Drying kinetics of carrot cubes were carried out at 1 m/s air velocity at different air
drying temperatures (30, 40, 50, 60 and 70±0.1 °C) (AIR experiments), and also at the same
experimental conditions but applying high power ultrasound (US experiments). Two kind of
diffusion models were used to simulate the drying kinetics, according to external resistance to mass
transfer being considered (ER model) or neglected (NER model) for solving the diffusion equation.
Diffusion ER model was solved using a finite difference method. Drying rate increased as air
temperature was higher. Ultrasound also increased drying rate at the different temperatures, but the
improvement on drying rate decreased at high temperatures, and almost disappeared at 70 °C.
Effective moisture diffusivities only showed an Arrhenius type relationship with temperature for
AIR experiments. The NER diffusion model was not accurate to simulate the drying kinetics at any
experimental conditions tested. However, diffusion ER model provided a high closeness between
experimental and calculated drying data (VAR>99.80). Through the parameters identified of the ER
diffusion model, effective moisture diffusivity and mass transfer coefficient, the influence of the
power ultrasound application on internal and external resistance to mass transfer was shown to be
significant (p<0.05).
Grain Boundary Self-Diffusion in Nickel
Authors: Rothová Vĕra , Buršík Jiří , Svoboda Milan , Čermák Jiří
Published: March 2009

Grain boundary self-diffusion in both the cast and the cold-rolled Puratronic 4N5 nickel
was studied in the temperature range from 600 °C to 1000 °C. The experiments were carried out
with the samples pre-annealed at 1100 °C in comparison to the samples pre-annealed at intended
individual diffusion temperatures. The relative grain orientation was analyzed on the same samples
by means of electron backscatter diffraction (EBSD) and grain boundaries (GBs) were characterized
in terms of the coincidence site lattice (CSL) model. Considering the non-linear Arrhenius
temperature dependencies obtained for most specimens by using conventional method of profile
evaluation in the B-type kinetics and the appearance of two high-diffusivity paths in diffusion
profiles measured, a more suitable BB-type and AB-type diffusion models were applied for data
evaluation.
Diffusion in Transition Metal Diborides - An Overview
Authors: Schmidt Harald , Borchardt Günter , Weber S. , Scherrer Hubert
Published: March 2009

Literature data on (self-)diffusion in transition metal borides are extremely sparse due to
the low atomic mobility of the constituents and due to the fact that for B there exist no suitable
radioactive tracers and only two stable isotopes with a high natural abundance of 19 % (10B) and 81
% (11B), respectively. The present paper reviews our experiments on the tracer diffusion of
transition metals and boron in TiB2, WB2+x, and (TixWyCrz)B2 which were carried out using stable
isotopes and secondary ion mass spectrometry (SIMS). For tracer deposition, ion implantation and
magnetron sputtering were used. In order to measure boron diffusion, a specially designed
experiment was build up where a TiB2 layer was sputtered on an isotope-enriched Ti11B2 bulk
ceramic sample. In addition, first results on chemical interdiffusion in the system (TixWyCrz)B2 will
be presented. Here, a method based on magnetron sputtered layers and secondary neutral mass
spectrometry (SNMS) was used which allows to determine much lower diffusivities (down to 10-19
m2/s) than the conventional EDX line-scan method on cross-sectional samples.
The Thermodynamic Database for the Development of Modern Lead-Free Solders
Authors: Kroupa A. , Vízdal J.
Published: March 2009

The methods for the modeling of thermodynamic properties of multicomponent systems
are described here. The rules for the creation of a consistent database for multicomponent systems
are described generally and documented on the Thermodynamic Database for Lead-free Solders
developed in the scope of COST 531 Action. The reassessment of the Sb-Sn system is shown as an
example, illustrating the application of consistency rules.
Thermal and Mechanical Stability of Polycrystalline Nanowires
Authors: Klinger Leonid , Rabkin Eugen
Published: March 2009

We considered a polycrystalline cylindrical nanowire with bamboo microstructure
strained uniaxially by an external load. Our molecular dynamic computer simulations
demonstrated that grain boundary grooving plays an important role in determining the
morphological stability of nanowires. Also, an exceptionally high yield stress of nanowires
emphasizes the importance of diffusion in their plastic deformation under applied load. We
formulated a phenomenological diffusion-based model describing morphological stability and
diffusion-controlled deformation behaviour of polycrystalline nanowires. The kinetics of the
shape changes was calculated numerically.
Interdiffusion Behavior in γ-Phase U-Mo Alloy versus Al-6061 Alloy Couples Fabricated by Friction Stir Welding
Authors: Keiser Dennis D.
Published: March 2009

To better understand interactions between fuel and cladding in research reactor fuels, diffusion couples between γ-phase U-7 wt% Mo and U-10 wt% Mo alloy fuels and a Si-bearing, Al alloy were fabricated using a friction stir welding technique. The advantage of such a fabrication technique is that it can potentially reduce the amount of aluminum-oxide that might be present at the diffusion couple interface. The presence of oxides at the interface can affect the interdiffusion process. These couples were annealed and characterized using a scanning electron microscope equipped with energy-dispersive and wavelength-dispersive spectrometers. Images were taken of the developed diffusion structures; x-ray maps were generated to identify partitioning behavior of the various components; and, point-to-point analysis was employed to generate composition profiles and to determine phase compositions. To try and determine how the presence of Si in an Al alloy affects the interdiffusion behavior of fuel and cladding components in research reactor nuclear fuels, the results from this study were compared to those from earlier diffusion studies using U-Mo alloys and Al. The formed diffusion zones in some samples annealed for 30 minutes are comprised of Si-rich aluminide phases that appear to be (U,Mo)0.9(Al,Si)4 and (U,Mo)(Si,Al)2, based on composition. The diffusion rates observed and the types of phases that form can be correlated to the stability of the γ-U phase, which is a metastable phase. For a sample annealed for a much longer time, large diffusion structures formed and no Si-rich phases were observed.
Influence of P/M Distaloy AE Steel Porosities and Nitriding Process Parameters in Diffusion and Configuration of Nitrided Layers Through Advanced Liquid Salt Bath Nitriding Process
Authors: Pirayesh N. , Teimouri M. , Khorsand H. , Khoie M. Mousavi
Published: March 2009

Nitriding process through a cyanate liquid salt bath is one of the advanced surface
treatment techniques that is recently employed to modify corrosion and wear resistance behaviour
of steels. Considering spreading out of P/M alloys application in various industries, especially
automotive industry, and the presence of porosities in its structure, in this research the influence of
porosities, process duration and temperature parameters in nitrogen diffusion and formation of
layers on a P/M Distaloy AE Steel through the advanced cyanate liquid salt bath nitriding process
has been investigated. Also it has been analyzed microstructure of layers by means of OEM, SEM
and microhardness deep profile investigations. Existence of ε (Fe2-3N) and γ' (Fe4N) phases was
detected by XRD analyzing. Results demonstrated that with increasing porosities, it was configured
a non-uniform diffusion regions on the surface due to nitrogen atoms dispersion.
Effect of Si on High-Temperature Oxidation of Steel during Hot Rolling
Authors: Suarez Lucia , Schneider Juergen , Houbaert Yvan
Published: March 2009

An oxide scale layer always forms at the strip surface during the hot rolling process.
As a consequence, de-scaling and pickling operations must be performed prior or after hot rolling.
Many surface defects caused by hot rolling are related to oxidation in the reheating furnace. One of
these is the melting of eutectic FeO/Fe2SiO4 during reheating over 1170°C giving as a result red
scale defects in Si-added steel. On the other hand, steel strip surface oxidation during hot rolling
causes an industrial and environmental problem: secondary oxide is removed after roughing, but
tertiary oxide scales already start to form before entering the finishing stands. Their properties affect
the final steel surface quality and its response to further processing. Furthermore, the addition of
alloying elements has an important impact on scale properties. In particular the alloying of silicon
effects the region between scale and substrate. It causes peculiar surface properties inherited from its
specific oxidation characteristics.
Conventional oxidation experiments in air of silicon steels are a valuable tool to study the
influence of Si on steel oxidation. After oxidation in air in the temperature range of 900-1250°C it
has been observed that Si enhance markedly scale adhesion, especially above 1177°C (the eutectic
temperature of FeO-Fe2SiO4 ) and also at lower temperatures. Special attention has been paid on the
investigation of the effects of alloying Si on the high-temperature oxidation of steel, for a better
understanding of the behaviour of modern steels during hot rolling.
Drying of a Low Porosity Product (Carrot) as Affected by Power Ultrasound
Authors: García-Pérez J.V. , Cárcel J.A. , Benedito J. , Riera E. , Mulet A.
Published: March 2009

The main aim of this work was to assess the influence of power ultrasound on mass
transfer process during convective drying of a low porosity product submitted to different acoustic
energy levels.
Drying kinetics of carrot cubes (side 8.5 mm) were carried out at 40 °C and 1 m/s applying
different electric power levels to the ultrasonic transducer: 0, 10, 20, 30, 40, 50, 60, 70, 80 and 90
W. Drying kinetics were modelled considering the diffusion theory.
From the results, a significant (p<0.05) influence of power ultrasound application on drying
kinetics of carrot cubes was found. Drying rate increased as the electric power applied got higher.
The influence was only observed above an acoustic energy threshold, which corresponded to an
electric power applied to the transducer of 20-30 W. From this threshold, a linear relationship was
found between the average effective moisture diffusivity or the mass transfer coefficient and the
electric power applied to the transducer.
Limits to N-Type Doping in Ge: Formation of Donor-Vacancy Complexes
Authors: Coutinho J. , Janke C. , Carvalho A. , Öberg Sven , Torres Vitor J.B. , Jones R. , Briddon Patrick R.
Published: March 2009

Vacancies and interstitials in semiconductors play a fundamental role in both high
temperature diffusion and low temperature radiation and implantation damage. In Ge, a seri-
ous contender material for high-speed electronics applications, vacancies have historically been
believed to dominate most diffusion related phenomena such as self-diffusivity or impurity mi-
gration. This is to be contrasted with silicon, where self-interstitials also play decisive roles,
despite the similarities in the chemical nature of both materials. We report on density func-
tional calculations of the formation and properties of vacancy-donor complexes in germanium.
We predict that most vacancy-donor aggregates are deep acceptors, and together with their high
solubilities, we conclude that they strongly contribute for inhibiting donor activation levels in
germanium.
Simulation of Pressure Effects on Self-Diffusion in BCC Metals
Authors: Valikova Irina , Nazarov Andrei V.
Published: March 2009

This work is devoted to the study of the point defect diffusion features in metals. In
particular, we propose the model, which allows calculating activation volumes that describe the
influence of pressure on the diffusion processes in solids. Our model realizes a new approach that
makes it possible to self-consistently determine atomic structure near defect and constants
characterizing the displacement of atoms in an elastic matrix around computational cell. Also we take
into consideration that the energy of perfect system and system with a defect differently depends on
the outer pressure, and this gives an addition to the values of migration and formation volumes. This
addition can comprise a considerable part of activation volume. Moreover, we take into account that
the atomic jump is a momentary process and so we carry out only partial relaxation of the atomic
structure in the vicinity of a defect. The formation and migration energies and formation and
migration volumes have been calculated for vacancies, di-vacancies and interstitials in bcc iron and
tungsten using pair and many-body potentials.
Kinetic and Thermodynamic Precipitation Parameters of the Pb-Sn Solid Solutions
Authors: Bondarenko Yu.O. , Voronina N.F. , Shmatko O.A.
Published: March 2009

Stages of cellular precipitation for the supersaturated Pb-Sn solid solutions were
analyzed. This was done for almost the whole homogeneity interval. Literary heritage as well as the
data of the present authors concerning kinetic and thermodynamic parameters of cellular
precipitation for these solid solutions were compared and summarized. It was shown that the
segregation factor, which characterizes the impurity atoms behavior at the grain boundary, decreases
with solid solution supersaturation increase.
Synthesis and Characterization of Ba Defective ZnO Nano-Particle
Authors: El-Hofy M. , Salama A.
Published: March 2009

ZnO-BaO particles (4-10) nm have been synthesized by applying 40 KHz ultrasonic wave simultaneously with the co-precipitation process of Zn and Ba oxalate at 50 0C. DTA curves of the co-precipitate were carried out and the decomposition temperature was determined. Mixed oxide obtained from thermal decomposition of Zn2 Ba (C2O4)2.2H2O in air has been investigated by TEM, XRD, IR and UV-Vis measurements. The results revealed that the obtained particle consists of a core of highly deformed Ba contaminated ZnO nano-crystals. The ZnO crystalline core is coated by Ba rich amorphous layer which prevents its growth. Decreasing concentration of ZnCl2 in the precipitation solution from 0.1M to .05 M leads to decrease the size of the particle from (10-20) nm to(4-10) nm, in average, increases UV cut-off, the cut-off tail and rounded of the shape of the particle.
Towards a Correlation between High-Temperature Creep and Volume Diffusion for Equiatomic NiTi Alloys
Authors: Taillebot Virginie , Divinsky S. , Lexcellent Christian , Bernardini Jean , Beke Dezső L.
Published: March 2009

Classically a master curve as Dorn's equation is applied for elucidating stationary creep behaviour within high temperature range (T > 0.6 Tm). As the diffusion of both 63Ni and 44Ti have been measured in an equiatomic NiTi, an effective choice of creep-relevant diffusion coefficient D may be possible. Moreover, creep measurements in the same temperature range performed can be found in the literature. The correlation does not permit to establish precisely what D coefficient to integrate in the Dorn's equation.
Lattice Boltzmann Simulations for Thermal Conductivity Estimation in Heterogeneous Materials
Authors: Arab M.R. , Pateyron Bernard , El Ganaoui Mohammed , Calvé Nicolas
Published: March 2009

For simulating flows in a porous medium, a numerical tool based on the Lattice Boltzmann Method (LBM) is developed with regards to the classical D2Q9 model. A short description of this model is presented. This technique, applied to two-dimensional configurations, indicates its ability to simulate phenomena of heat and mass transfer. The numerical study is extended to estimate physical parameters that characterize porous materials, like the so-called Effective Thermal Conductivity (ETC) which is of our interest in this paper. Obtained results are compared with those which could be found analytically and by theoretical models. Finally, a porous medium is considered to find its ETC.
Treatment of Surface Properties of Titanium with Plasma (Ion) Nitriding
Authors: Yilmazer H. , Yilmaz S. , Acma M.E.
Published: March 2009

In order to improve the poor surface hardness and the wear resistance, titanium has been nitrided with plasma (ion) nitriding which is one of the methods to treat surface properties of titanium alloys. The increment at surface hardness and so the wear resistance of nitrided titanium alloys has been provided by means of compound layer (ε-Ti2N+δ-TiN) and diffusion zone (α-Ti) occurred by plasma ion nitriding. The goal of the present paper is to investigate effects of nitriding temperature and nitriding time on the microstructure and hardness value of nitrided surface layers. A systematic study was undertaken with specimens of commercial pure Ti and Ti-6Al-4V alloy. As treatment parameters, we have used; nitriding time (from 2 to 9 hour), nitriding atmosphere (H2-80%N2), total pressure (1 kPa) and cathode temperature (from 600 to 800 oC). The Vickers indenter was used for analysis of the micro hardness measurements. The thin hardened layer at the nitrided surface was characterized by glancing-angle X-ray difractometer. X-ray diffraction analysis has confirmed the formation of ε-Ti2N and δ-TiN phases on the nitrided specimens. Experimental details and characterization of plasma (ion) nitrided titanium have reported and discussed.
Development of Al-Mg Based Composites Containing Nanometric Alumina Using the Technique of Disintegrated Melt Deposition
Authors: Ho K.F. , Gupta Manoj
Published: March 2009

In this study, composites based on Al-Mg/Al2O3 formulation were fabricated using an innovative solidification route followed by hot extrusion. The studies clearly indicate an increase in retention of nanometric alumina with an increase in magnesium content. Microstructural characterization studies of the extruded composite samples displayed fairly uniform distribution of reinforcement phases and minimal porosity. Results of mechanical properties characterization showed that a cumulative increase in magnesium and nanometric alumina content led to an increase in elastic modulus, 0.2% YS and UTS while the ductility of the composite was adversely affected. A comparison between monolithic Al-3.8Mg and Al-3.4Mg/1.4Al2O3 revealed that the presence of nanometric alumina play a dominant role in realizing a significant increase in elastic modulus, 0.2%YS and UTS of the composites.
The Carbon Nanotubes with Different Chemical Treatments and Their Electrochemical Voltammetric Reponses
Authors: Hu C.G. , Wang W.L. , Feng Bo , Liu G.B.
Published: March 2009

The carbon nanotubes with carboxyl groups were obtained by using different
chemical treatment methods. The electrical properties of the carbon nanotube films were investigated and voltammetric responses for Fe3+ / Fe2+ were measured at the carbon nanotube film electrodes.
Computational Issues in Biomedical Nanometrics and Nano-Materials
Authors: Huang Heng , Shen Li , Ford James , Wang Yu Hang , Xu Yu Rong
Published: March 2009

Biomedical Nanotechnology is an emerging area of great scientific and technological opportunity. It is widely recognized as one of the most potentially beneficial applications of nanotechnology to industry and society to date. Work in this area has a number of computational aspects: information technology based tools and measurement techniques are used to study biosystems with micro- and nano-scale physics and chemistry, and computational methods are helping to generate remarkable new insights into how biological systems function, how metabolic processes interrelate, and how new molecular scale machines can operate. This paper reviews current advances in computational algorithms and tools applied to biomedical nanometrics and nano-materials. We categorize algorithms into three general areas, describe representative methods, and conclude with several promising directions of future investigation.
Oxygen/Carbon Ratio Effects on Surface-Modified Carbon Nanotubes
Authors: Chen U.S. , Su Heng Yi , Wang Chung Hao , Shih Han Chang , Hsieh Chien Te , Chen Jin Ming
Published: March 2009

Carbon nanotubes (CNTs) were functionalized using a simple method of heat treatment
under oxygen atmosphere followed by an immersion in a tin nitrate aqueous solution. And
well-dispersed SnOx nanodots were decorated on the surface of CNTs. X-ray photoelectron
spectroscopy (XPS) analysis showed that the O/C ratio increases with oxygen-treated time. The
distribution of carbon-containing functional groups on the CNTs surface, i.e., C−C, C−O, C=O,
O−C=O, and π−π* shake up bonds can be identified and deconvoluted by a symmetrical Gauss
function. The contact angle of H2O and CNTs is dependent on O/C ration. The relationships between
the fraction of carbon-containing functional groups and various oxygen treatment times are also
discussed.
X-Ray Diffraction Studies of Nanostructured Metallic Alloys
Authors: Bedboudi H. , Bourbia A. , Draissia M. , Debili M.Y.
Published: March 2009

X-ray tools are being powerful methods for qualitative and quantitative analyses of nanocrystalline materials This work is an overview of detailed X-ray investigations relative to microstructural studies applied for a refined binary Al-based alloys thin films system as samples deposited on glass substrates. Energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods were used to determine the chemical composition, the microstructure parameters and the solubility of copper in aluminum.
Solid State NMR Evaluation of Natural Resin/Clay Nanocomposites
Authors: O. da Silva Emerson , Tavares Maria I.B. , Nogueira José S.
Published: March 2009

NMR nuclear relaxation times have been used by Tavares et al as a methodology to characterize the nano materials, especially nanocomposites, because NMR offers a great variety of relaxation parameters. The spin-lattice relaxation time, with a time constant T1, have been explored to get as much information as possible from the measurements of the spin-lattice proton relaxation (T1H), which can measure the fraction of available polymer/clay interface as well as the dispersion homogeneity of those interfaces actually formed. The spin-lattice has been evaluated since this relaxation time confirms the T1 and can give additional information to nanocomposite clay dispersion. The NMR relaxation times are sensitive to the chemical environmental, changes in the polymer matrix; chemical structure and interaction process, because they depend on the domain distribution and sample homogeneity, since they are measured in the solid state via intermolecular chains interaction and/or spin diffusion. The T1 relaxation time of the nanocomposite decreased very much in relation to the natural resin, according to the increase in the exfoliation clay process, forming a nanocomposite with polymer matrix around the clay lamella.
Adsorption of Molecular Hydrogen in a Graphene-Carbon Nanotube System
Authors: Arellano J.S.
Published: March 2009

In this theoretical study, the H2 adsorption is considered in a novel system formed by a (6,6) carbon nanotube fragment and a planar graphene layer portion, when they are separated 4.72 a.u., with both subsystems inside a cubic supercell box of 25 a.u. side. There is greater H2 adsorption inside the carbon nanotube than in the interstitial space between the graphene layer and the carbon nanotube. The results are compared with the way the H2 molecule is adsorbed upon a lonely graphene layer and inside or outside the (6,6) carbon nanotube. It is studied if in the interstitial space close to the middle point between the wall and the graphene layer the hydrogen molecule could be adsorbed with a greater binding energy that in any other case. This was not possible for the selected supercell, but there are given some suggestions to be explored (using a nanotube with smaller radii or increasing the size of the supercell), that perhaps can optimize the binding energy for H2 adsorption. A general result is that the size of the cubic supercell can be selected to confine not only hydrogen inside the carbon nanotube but also in the interstitial space between the carbon nanotube wall and the graphene layer. It is believed that the studied system or a modification of this could sooner or later be used in a competitive way in comparison with other H2 storage materials respect to the hydrogen adsorption and desorption process.
Optical Properties of Non-Periodic Dielectric Systems Made of Nanostructured Porous Silicon
Authors: Alvarado Tenorio B. , Escorcia-Garcia J. , Mora-Ramos Miguel Eduardo , Agarwal V.
Published: March 2009

To investigate the optical properties in non-periodic dielectric systems, we study here the reflection of light from nanostructured porous-silicon-based period doubling heterostructures. The multilayered systems are fabricated in such a way that the optical thickness of each layer is one quarter of 650nm. The results for the optical reflectance are presented and compared with that of Fibonacci, Thue-Morse, and random structures fabricated under the same conditions. Numerical simulation for the reflectance along the lines of the transfer matrix approach is performed. In addition, optical reflection from Gaussian porous silicon multilayers is also briefly discussed. We find that porous silicon Period Doubling dielectric multilayers could demonstrate the optical properties similar to the classical periodic Febry-Perot interference filters with one or multiple resonant peaks, but with an advantage of having total optical thickness much lesser than that of the periodic structures.
Effect of Chromium Doping on Visible Light Absorption of Nanosized Titania Sol-Gel
Authors: Pedraza-Avella J.A. , López R. , Martínez-Ortega F. , Páez-Mozo E.A. , Gómez Ricardo
Published: March 2009

Visible light absorption of TiO2 can be induced by the addition of transition metal impurities. However, many dissimilar results have been reported about this subject and there are various interpretations about the origin of these absorption features. In this work, samples of chromium-doped titania (TiO2-Cr) with different dopant contents (0.1, 0.5, 1.0 and 5.0 wt. %) were prepared by a sol-gel method. Their particle size was determined by dynamic light scattering and it was on the nanometer scale (18 nm). X-ray powder diffraction and Raman spectroscopy showed only the presence of anatase phase in all samples. X-ray photoelectron spectroscopy reveals that the oxidation state of chromium in the prepared materials is different than in the dopant precursor. This change can be associated to the oxidative gelling conditions used in the materials preparation. UV VIS diffuse reflectance spectroscopy showed that the chromium doping, until 1.0 wt. %, did not effectively narrow the TiO2 band-gap but it induces the visible light absorption probably through the formation of color centers.
Calculation of Magnetization and Phase Equilibrium in Fe-C Binary System under a Magnetic Field
Authors: Zhang Yu Dong , He Chang Shu , Zhao X. , Wang Yan Dong , Zuo Liang , Esling Claude
Published: March 2009

The Weiss model is extended by substituting the molecular field coefficient lwith a short-range-ordering coefficient g valid around and above Tc. The temperature variations of susceptibility of fcc Fe are calculated with a band model. Based on the above models, the phase equilibrium diagram of Fe-C binary system under a magnetic field is calculated.
Microstructure and Texture of Shear Bands in Cold Rolled Silicon Steel Single Crystals of Goss Orientation
Authors: Dorner Dorothée , Zaefferer Stefan
Published: March 2009

An initially Goss-oriented ({110}<001> preferred crystal orientation) FeSi single crystal was cold rolled up to 89 % reduction in thickness. The microstructure and texture of shear bands, which develop at strains higher than 70 %, were investigated by the EBSD (electron backscatter diffraction) technique. The texture components within and ouside of the shear bands are the two symmetrical {111}<112> orientations and the {110}<001> orientation. We conclude that crystallographic slip is the deformation mechanism that is active both within and outside of the shear bands.
Correlation of Texture and Plastic Anisotropy in the Al-Mg Alloy AA 5005
Authors: Engler Olaf , An Yuguo
Published: March 2009

The control of the plastic anisotropy during forming of a metallic sheet requires detailed knowledge on its microstructure and, especially, crystallographic texture. In the present paper the correlation of texture and plastic anisotropy in the Al-Mg Alloy AA 5005 is studied. Two different material states with different textures are compared, namely 1.7 mm thick soft-annealed material (O-temper) and 1.0 mm cold rolled strip (state H14). Tensile tests were carried out at 0°, 45° and 90° with respect to the sheet rolling direction and the resulting in-plane anisotropy in yield strength, work hardening and strain rate ratios (r-values) was determined. On a more general approach, texture-derived yield loci are compared with both phenomenological yield functions and experimental data.