bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass Transfer Analysis during Osmotic Dehydration of Eggplant Using Binary Solutions of Sucrose and Sodium Chloride
Authors: Moreira Ramón , Chenlo Francisco , Vallejo N. , Gerbet Lionel
Published: March 2009

Osmotic dehydration of eggplant slices in sucrose and sodium chloride solutions at
different solution concentrations, stirring levels and time of process is studied. Water loss and solids
gain kinetics were experimentally determined and modelled using a diffusional model and
equilibrium values were predicted by means of Azuara model. Modelling was satisfactory and
involved effective coefficients of diffusion useful to quantify the different mass transfer fluxes.
Theoretical Studies of Diffusion Kinetics in Austenite
Authors: Evteev Alexander V. , Levchenko Elena V. , Belova Irina V. , Murch Graeme E.
Published: March 2009

We report on the computer simulation (using molecular dynamics and lattice relaxation)
to explore tracer and chemical diffusion (carbon) kinetics in austenite at low carbon contents. It was
found by molecular dynamics simulations that the detailed balance relations are not valid for the
second nearest neighbours in the movements of the carbon interstitial atoms. The effect of a
possible split energy level at the second nearest neighbour positions is analysed from a theoretical
point of view.
Interfacial Reactions during the Dissolution of Titanium in Liquid Iron
Authors: Pandelaers Lieven , Verhaeghe Frederik , Blanpain Bart , Wollants Patrick
Published: March 2009

The interfacial reactions between a solidified Fe shell and Ti were investigated within the
framework of steel alloying. Ti cylinders were immersed into liquid Fe for various durations and
subsequently water-quenched. An Fe shell solidifies around the Ti. At the interface between Fe
and Ti a reaction zone is formed. Initially it consists of a liquid eutectic layer, though in later stages
all stable phases at elevated temperature can be found in the quenched microstructure. The larger
part of this reaction zone is fluid at high temperature and both Ti and Fe dissolve into it. Moreover,
intermetallic compound formation and mixing of Fe and Ti generate extra heat, shortening the time
required for shell melt-back. The reaction zone reaches thicknesses up to 40 % of the initial
sample’s radius and when the shell has completely remolten, a discontinuity in the thickness-time
profile is expected. The exact morphology of the reaction zone at high temperature remains to be
determined: presence of a solid layer of Fe2Ti may impede mixing in the initial stages.
Mass Transfer Kinetics in the Desulphurisation of Pig Iron with CaO and CaC2
Authors: Ochoterena Luis , Reyes Fidel , Ingalls Alberto , Gutiérrez Juliana , Plascencia Gabriel
Published: March 2009

This paper discusses the effect of the main parameters that affect the desulphurization
reaction efficiency. The study was conducted by evaluating different reaction sites within the metal,
the slag and the reducing agents. It was possible to establish a mass transfer model that determines
the amounts of the reducing agents needed to maintain adequate sulphur levels in the pig iron.
Industrial trials showed the accuracy of our model.
Kinetics Parameters of Atomic Migration and Diffuse Scattering of Radiations within the F.C.C.-Ni–Al Alloys
Authors: Leonov D.S. , Radchenko Taras M. , Tatarenko Valentin A. , Kunitsky Yu.A.
Published: March 2009

Relaxation of diffuse-scattering intensities of various kinds of waves is a phenomenon of an
especial interest since its study enables one to obtain the most detailed information on both the equilibrium
short-range order (SRO) and the non-equilibrium SRO, and therefore, it is the most convenient
instrument for investigating SRO kinetics. The SRO kinetics is studied by the use of available data of
measurements of residual electrical resistivity for substitutional f.c.c.-Ni–Al solid solutions during
their isothermal annealing. Within the framework of the first-order and (more realistic) second-order
kinetics models, the maximum characteristic relaxation times and equilibrium magnitudes of the residual
electrical resistivity for these solid solutions at different annealing (1273–1626 K) and quenching
temperatures (≥ 1723 K) are evaluated, and the hypothetical values of similar quantities appropriate
for the diffuse scattering of radiations are estimated too.
Diffusion-Evaporation Studies of Binary Mixtures in Capillary Tubes
Authors: Duursma Gail , Sefiane Khellil , Clarke Joy
Published: March 2009

Evaporation in restricted domains, e.g. in capillaries, is of industrial importance but is
poorly understood. Where the evaporating liquid is a binary mixture, preferential evaporation of the
more volatile component occurs initially and the evaporation rate is not constant, indeed it appears
to occur in stages. Experiments of evaporation from the entrance of a capillary were performed for
various binary mixtures of acetone and water and for pure liquids for comparison. Measurements of
mass were taken over time for a range of capillary diameters from 0.6 mm to 2 mm. For simplicity,
the experiments were performed with the meniscus “stationary” at the entrance of the tube, rather
than allowing the meniscus to recede. The data were analysed and showed that, for the binary
mixtures, the evaporation process had two distinct stages for the mixtures. The second stage always
had a lower slope than the first, indicating a slower evaporation (similar multistage evaporation
processes have been observed for sessile drops of binary mixtures). There are many phenomena at
work in this process: surface evaporation; diffusion (or natural convective mass transfer) in the air
beyond the capillary; diffusion in the binary mixture; circulation in the liquid; thermal effects of
evaporative cooling. These are investigated, comparisons made and further studies are proposed.
Effect of Sodium Borohydride on the Hydrogen Diffusion in MmNi3.6Mn0.4Al0.3Co0.7 Hydride Electrode
Authors: Sequeira César A.C. , Chen Yun , Santos Diogo M.F.
Published: March 2009

Anodic polarisation curves of treated and untreated MmNi3.6Mn0.4Al0.3Co0.7
(Mm = mischmetal) electrodes were measured under the conditions of various initial concentrations
of absorbed hydrogen (H/M), rates of potential sweep and temperatures. The alloy powders of the
electrodes were treated with 6 M NaOH solution containing y M NaBH4 (y = 0.0, 0.005, 0.01, 0.02,
0.03 and 0.05). The initial concentration of absorbed hydrogen in the electrodes varied between 0
and 0.06 H/M, and the working temperature range was 15 °C to 50 °C. Anodic peak current (Ip) at
the MmNi3.6Mn0.4Al0.3Co0.7 electrodes increased with an increase in the y value. In addition, the Ip
value depended linearly on initial hydrogen concentration and square root of potential rate
irrespective of y value. Furthermore, the activation energy for hydrogen diffusion decreased with an
increase in y value. From these results, it is considered that the hydrogen diffusion in the
MmNi3.6Mn0.4Al0.3Co0.7 alloys and the electrocatalytic activity at their surfaces influence the Ip
value and that they are important factors for improving the charge-discharge performance of the
negative hydride electrode. Its low temperature (15-30 °C) performances are also improved by the
simple powder treatment with the 6 M NaOH solution containing NaBH4 as reducing agent.
Wagnerian Scaling Diffusion Kinetics
Authors: Sequeira César A.C.
Published: March 2009

The reaction of a metal or alloy with an oxidising environment to form a scale often
involves a diffusion process as the rate limiting step. The most protective oxide scales are slow
growing, adherent to the substrate, and free of cracks or pores. The growth of these scales is
typically by solid state diffusion of metal or oxygen ions that move via point defects in the oxide
lattice. In 1933, C. Wagner established a scientific basis for oxidation processes controlled by solid
state diffusion, with his celebrated derivation of the parabolic rate constant, which connects scaling
rates, diffusion coefficients, point defect concentrations, point defect types, and effect of external
parameters, e.g. pO2. These aspects are discussed in this paper. The importance of the Wagnerian
theory is to provide a relatively simple model upon which more comprehensive models may be built.
For many applications, the rate of degradation of the metal or alloy, owing to oxidation by lattice
diffusion would be quite acceptable. Several examples of oxidation processes controlled by vacancy
and/or interstitial diffusion will be discussed.
Isothermes of Surface and Grain Boundary Tension of Cu-Based Alloys with Sb, Sn, In
Authors: Gershman Evgeny I. , Zhevnenko Sergei
Published: March 2009

Grain boundary and surface tension for pure copper and copper-based alloys with Sb, Sn
and In are measured by zero creep method. On the base of these and literature data, using the
Shyshkovsky equation for a dilute solution, the isothermes of surface tension and grain boundary
tension are constructed in Cu-based alloys with Sb, Sn, In and also Bi and Au. It is shown that all
solutes are active on the surface tension of copper. The free energies of adsorption are negative and
decrease in a following consequence: Bi, Sb, Sn, In, and Au.
Production of Electrical Steel by Hot Dipping in Aluminium
Authors: Rodriguez-Calvillo Pablo , Bernárdez P. , Houbaert Yvan
Published: March 2009

The addition of aluminium (and of silicon) to steel increases its electrical resistivity
and reduces therefore the power losses in electrical devices. There is also a favourable effect on
magnetostriction. Nevertheless, these additions make the steel extremely brittle and very difficult to
process through a conventional thermomechanical route.
The authors developed an innovative processing route, avoiding the rolling of a brittle steel
sheet. The used process consists of the hot dipping of a steel substrate in a pure aluminium bath,
followed by a diffusion annealing treatment.
In order to study the reaction of the aluminium with the substrates and the diffusion process
during further annealing, two substrates (ultra low carbon steel (ULC) and a Fe + 3.4 m.-% Si steel)
were used for immersion in a pure aluminium bath. Dipping times and temperatures were varied in
the range of 700 to 750 °C and 5 to 1000 sec., respectively. The different surface layers formed
during dipping and after annealing were characterised with an Elcometer, by Scanning Electron
Microscopy (SEM) and by Energy Dispersive Spectroscopy (EDS).
The results show that the chemical composition of the layers obtained is strongly dependant on
the initial substrate composition. Diffusion gradients of Al and Si in the steel after hot dipping and
diffusion annealing are shown and discussed. Samples with a concentration gradient of Si and Al
over the thickness have been produced. There is only a light reduction of the power losses for the
substrate with 3.4 m.-% Si. The ultra low carbon substrate presents worse power losses after the
processing. Further improvement of the processing is still required.
Effect of the SiO2/Si Interface on Self-Diffusion in SiO2 Upon Oxidation
Authors: Uematsu Masashi , Ibano Kenzo , Itoh Kohei M.
Published: March 2009

The effect of the SiO2/Si interface on Si self-diffusion in SiO2 during thermal oxidation
was investigated using silicon isotopes. Samples with natSiO2/28Si heterostructures were oxidized at
1150 ~ 1250 °C and the 30Si diffusion in 28SiO2 during the thermal oxidation was investigated by
secondary ion mass spectrometry (SIMS) measurements. Near the SiO2/Si interface, a significant
profile broadening of the 30Si isotope from natSiO2 toward the newly grown 28SiO2 was observed.
This 30Si self-diffusivity sharply decreases with oxidation time and hence with increasing distance
between 30Si diffusion region and the interface. This distance-dependent 30Si self-diffusion was
simulated taking into account the effect of Si species generated at the interface upon oxidation and
diffusing into SiO2 to enhance Si self-diffusion. The simulation fits the SIMS profiles and these
results indicate that Si species, most likely SiO, are emitted from the SiO2/Si interface upon Si
thermal oxidation to release the oxidation-induced stress, as has been predicted by recent theoretical
studies. Furthermore, combined with our recent results on O self-diffusion, the diffusion behavior of
the emitted SiO near the SiO2/Si interface is discussed.
Modelling of Stable Fission Gases Diffusion in UO2 Nuclear Fuel
Authors: Vallejo Isabel , Herranz Luisen E.
Published: March 2009

The current trend in nuclear industry to extend the burnup limits up to high burnup
requires the analysis of the phenomenology related to the nuclear fuel, specifically the diffusion and
fission gas release (FGR) related to this phenomenon plays an important role. In this paper, the
diffusion of stable fission gases (xenon and krypton) in nuclear fuel UO2 is addressed through the
predictions for FGR to rod void volumes obtained with FRAPCON-3 fuel performance code. The
theoretical base of diffusion model in FRAPCON-3 code is shown and some modifications are
proposed, such as the removing of empirical correlations not related to diffusion phenomenon and
fitting parameters included in the model. Besides, the resolution process in the proximities of grain
boundaries is considered in a different way, and the grain growth mechanism from a specific
temperature threshold is implemented into the code. The database applied for evaluation is
presented and the results with the original and modified model are shown.
Study of Distribution of Impurity Atoms in Metallurgical Macrodefects
Authors: Vykhodets V.B. , Kurennykh Tatiana Eugenievna , Tarenkova N.U.
Published: March 2009

Using nuclear microanalysis (NRA) and electron probe microanalysis (EPMA),
concentrations of carbon, oxygen, nitrogen, aluminum, and vanadium were measured on a large
group of macrodefects formed in the course of smelting titanium alloys. A remarkable enrichment
of the defect material in oxygen and nitrogen atoms was detected; histograms of defect distribution
over the concentrations of oxygen, nitrogen, aluminum, and vanadium were obtained. The above
results agree with the concepts according to which the defects are formed from the particles that
have the melting temperature higher then the temperature of smelting.
Dependence of Diffusion Paths on Thermodynamic Factors in Ternary Systems
Authors: Ugaste Ü. , Priimets J. , Laas Tony
Published: March 2009

The impact of thermodynamic factors on deviation from linearity of diffusion path in the
ternary system Cu-Fe-Ni is analyzed. For that the slope function of the diffusion path for the
diffusion couples 65Ni30Cu5Fe –29.5Ni16.5Cu54Fe, 49.5Ni50.5Fe – 51Ni49Cu and 84Cu16Ni –
50Ni50Fe, annealed at 1000°C for 196h, were calculated by an approximate equation using only
thermodynamic data. Results of the calculation were compared with the values of the slope function
obtained directly from experimental data. It is shown that despite of the fact that the tracer diffusion
coefficients of the components in the system Cu-Fe-Ni are not equal the coincidence between the
calculated and experimental values of the slope function is remarkable. This allows us to conclude
that at least in this case the deviation of the diffusion path from linearity depends mainly on the
thermodynamic properties of the system.
Numerical Simulation of Precipitates Evolution in Iron-Based Alloys
Authors: Popov Vladimir V.
Published: March 2009

Approaches used for simulation of precipitates evolution in multicomponent systems are
analyzed in brief. Simulation of precipitates growth and dissolution in such systems, simulation of a
polydisperse particle ensemble evolution at different stages and possibilities of taking into account
nucleation during precipitates growth from a supersaturated solid solution are considered by an
example of iron-carbon alloys. The problems to be solved are formulated.
Complex Phase Behavior of Systems with Negative Curvature Potentials
Authors: Fomin Yu.D. , Gribova N.V. , Ryzhov V.N.
Published: March 2009

The comprehensive computer simulation study of the phase diagram of the repulsive step
potential system in three dimensions is represented. We show that the system with a simple purely
repulsive isotropic potential demonstrates a number of unusual features. The maxima and minima
on the melting curve are found for some regions of potential parameters. It is shown that the phase
diagram in ρ-T plane includes two isostructural crystalline parts separated by the disordered phase
which is amorphous at low enough temperatures. Phase diagram in the (P-T) plane shows that the
transition to the amorphous state occurs approximately along the extrapolated spinodals. Structural
FCC-BCC phase transition is found at high densities.
3D Monte Carlo Simulation of Phase Separation Kinetics in a Binary Metallic Alloy with Vacancy Mediated Diffusion: Effect of Initial Supersaturation
Authors: Shirinyan A.S. , Bilogorodskyy Yu. S.
Published: March 2009

The process of phase formation at the initial stage of the reaction diffusion and growth of
a new phase particles - at the atomic level by applying the Monte-Carlo simulation of the crystalline
nanoalloy is presented. The influence of initial composition on the kinetics of phase separation in a
binary alloy with the fcc crystal lattice has been analyzed in detail. The dependences of various
parameters of tire process - the average size of new-phase particles, volume of new-phase clusters,
size distribution function, dispersion and supersaturation - on time have been calculated. The
obtained results demonstrate the opportunity of a three-stage separation process at low initial
supersaturation values and a two-stage separation at large initial supersaturation values.
Composition Fluctuations in the Ostwald Ripening
Authors: Lutsenko G.V. , Gusak Andriy
Published: March 2009

The Ostwald ripening of a two-phase binary alloy has been considered for case of “large”
volume fraction of precipitating phase. The approach is proposed in which the composition
fluctuations into the vicinity of particles are considered. In this approach the evolution of particle
size distributions is analyzed using the computer simulation.
Modelling of the Formation of Pd-Ni Alloy Nanoparticles by Interdiffusion
Authors: Evteev Alexander V. , Levchenko Elena V. , Belova Irina V. , Murch Graeme E.
Published: March 2009

Long–time scale molecular dynamics simulation in combination with the embedded atom
method is used to investigate the effect of surface segregation phenomena at 1000 K on the structure of
Pd alloy nanoparticles (of diameter of ∼ 4.5 nm) containing ∼ 30 at. % Ni. A core–shell f.c.c. structure
was chosen as the initial state wherein a core of Ni atoms is surrounded by shell of Pd atoms. It is found
that such nanoparticles form a surface–sandwich structure by interdiffusion. In this structure, the Ni atoms,
which mostly accumulate in a layer just below the surface and at the same time are located in the centres
of interpenetrating icosahedra to generate a subsurface shell as a Kagomé net. Meanwhile, the Pd atoms
occupy the vertices of the icosahedra and cover this Ni layer from inside and outside as well as being
located in the core of the nanoparticle forming (according to alloy composition) a Pd–rich solid solution
with the remaining Ni atoms. The total atomic fraction involved in building up the shell of the nanoparticle
in the form of the Ni Kagomé net layer covered on both side by Pd atoms can be estimated at ∼ 70 %.
Theoretical Analysis and Atomistic Modelling of Diffusion and Stability of Pure Element Hollow Nanospheres and Nanotubes
Authors: Evteev Alexander V. , Levchenko Elena V. , Belova Irina V. , Murch Graeme E.
Published: March 2009

A theoretical and atomistic study of diffusion and stability of a pure element hollow nanosphere
and nanotube is performed. The shrinkage via the vacancy mechanism of these hollow nano-objects is
described analytically. Using Gibbs-Thomson boundary conditions an exact solution of the kinetic
equation in quasi steady-state at the linear approximation is obtained. The collapse time as a function of
the geometrical sizes of the hollow nano-objects is determined. Kinetic Monte Carlo simulation of the
shrinkage of these nano-objects is performed: it confirms the predictions of the analytical analysis. Next,
molecular dynamics simulation in combination with the embedded atom method is used to investigate
diffusion by the vacancy mechanism in a Pd hollow nanosphere and nanotube. It is found that the diffusion
coefficient in a Pd hollow nanosphere and nanotube is larger near the inner and external surfaces compared
with the middle part of a nanoshell. The molecular dynamics results provide quite a strong but indirect
argument that a real pure element hollow nanosphere and nanotube may not shrink as readily via the vacancy
mechanism as compared with the predictions of the analytical analysis and kinetic Monte Carlo simulations.
Reactionary Interaction as the Basis of Occurrence Heterogeneity Diffusion Properties Grain Boundaries in Polycrystalline Silver
Authors: Koloskov Valerie M. , Gapontsev V.L.
Published: March 2009

The new way of calculation of segregation enthalpy on the basis of grain boundary
diffusion data is offered. It proceeds from the primary data on an interval "B"- regime of grain
boundary diffusion. For data processing we used the expression for coefficient of grain boundary
diffusion got by Borisov and Lubov according to Fisher model for a tail part of the concentration
curve. To approve this approach the data of tellurium diffusion in grain boundary of polycrystalline
silver are considered.
Effect of Substrate Temperature on the Different Diffuseness of Subsequent Interfaces in Binary Multilayers
Authors: Kis-Varga Miklos , Langer G.A. , Csik A. , Erdélyi Z. , Beke Dezső L.
Published: March 2009

Epitaxial, coherent Mo/V multilayers were deposited by magnetron sputtering on (001)
oriented MgO substrates at 873K (sample MoV-T), 923K (sample MoV-U) and 973K (sample
MoV-V), respectively. In order to estimate the concentration profiles in our multilayers, a
superlattice refinement modelling procedure has been used on high-angle XRD symmetric scans.
The Mo/V interfaces were always sharper than V/Mo ones (in this notation the order of element
reflects the sequence of deposition: e.g. the Mo/V interface was formed by the deposition of the V
on the Mo surface). Furthermore the interface diffuseness was only slightly different at the lowest
substrate temperature, but the difference increased with increasing temperature and an abrupt
concentration jump could be observed at the Mo/V interface in the sample, sputtered at the 973 K.
This indicates that during deposition the interfacial mixing by impact exchange events is important
and thermally activated processes (surface diffusion and/or jumps driven by segregation) are less
effective. With increasing substrate temperature the thickness of the V/Mo interfaces were
unchanged while the Mo/V interface became shaper and sharper i.e. thermally activated jumps were
more active during deposition of V atoms. Thus in forming Mo/V interfaces the segregation
tendency of V to the Mo surface results in enhanced exchanges between V atoms (buried in the near
surface layers of the Mo substrate) and surface Mo atoms, leading to more sharper interface with
increasing temperature. On the other hand during the formation of the V/Mo interfaces the chemical
thickness of the interface, provided again by impact exchanges, was practically unchanged.
Suppression Criterion of the Phase Growth Based on Extremal Principles of Nonequilibrium Thermodynamics
Authors: Lyashenko Yu.A.
Published: March 2009

The suppression criterion of the binary phase growth due to addition of a third component
is considered. In this case the analysis of the two possible criteria of the first phase growth are
considered: first – kinetic criterion based on the balance of components fluxes and second -
thermodynamic criterion which is based on the maximal rate of the entropy production principle.
We demonstrate that in the case of a model system the thermodynamic criterion lead to a bigger
value of the critical thickness of the phases which are suppressed by the growth of the investigated
phase.
Mechano-Chemistry; Interdiffusion in Solid Solutions
Authors: Danielewski Marek , Wierzba Bartłomiej
Published: March 2009

In this work we show that the volume velocity, ρυ , rather than the local centre of mass
velocity should be used in continua. We use the volume continuity equation to define the volume
frame of reference in the multicomponent, compressible continua. The volume velocity (material
velocity) is a unique frame of reference for all internal forces and processes, e.g., the mass diffusion.
No basic changes are required in the foundations of linear irreversible thermodynamics except
recognizing the need to add volume to the usual list of extensive physical properties undergoing
transport in every continuum. The volume fixed frame of reference allows the translation of the
Newton’s discrete mass-point molecular mechanics into continuum mechanics and the use of the
Cauchy linear momentum equation of fluid mechanics and Navier-Lamé equation of mechanics of
solids. Our proposed modifications of Navier-Lamé and energy conservation equations are selfconsistent
with the literature for solid-phase continua dating back to the classical interdiffusion
experiments of Kirkendall and their subsequent interpretation by Darken in terms of diffusive
volume transport. We do show that the local diffusion processes do not change the centre of mass of
the system and that the internal stress depends on the gradient of the local volume velocity only.
Diffusion Formation of Silicide Phases in Ni/Si(001) Nanodimensional Film System
Authors: Sidorenko Sergey I. , Makogon Yu.N. , Voloshko S.M. , Pavlova O.P. , Kotenko I.E. , Mogilatenko A.V. , Beddies G.
Published: March 2009

Thermally stimulated solid state reactions in the Ni(10 nm)/Si(001) film system that occur under the annealing in the nitrogen ambient were researched by methods of сross-sectional transmission electron microscopy and scanning electron microscope. It was established that NiSi2 formation consists of several steps: a formation of the NiSi polycrystalline silicide thickness of which twice higher initial thickness of Ni layer; prevailed diffusion of Ni atoms out of NiSi into Si substrate according with lattice mechanism and appearing of exceeding vacancies at grain boundaries; a formation of epitaxial NiSi2 nuclei at separate spots of NiSi/Si(001) interface; regular growth of NiSi2 phase inclusions at the expense of NiSi layer “diffusion dissolution”; a formation of NiSi2 spherical inclusions in the lattice of Si matrix and their coalescence.
Steam Oxidation Behaviour of Ni-Based Alloys
Authors: Fujikawa Hisao
Published: March 2009

The steam oxidation behavior and the oxide scale structure of Ni-based alloys containing 20 to 25 mass% Cr content were studied. The oxidation test was carried out from 550 to 700°C at 50°C intervals for 100 hours in steam.
All Ni-based alloys used showed good steam oxidation resistance; higher Cr containing alloys have a little better oxidation resistance than lower Cr containing alloys. The kinetics of the oxidation rate of all Ni-based alloys used was estimated as the temperature parameter in a 100 hour test and as the temperature and time parameters, respectively. These equations could be useful for industrial applications. The oxide scale of Alloy 625 was composed of two layers. The outer layer was composed of needle-like oxides and the inner layer was composed of isometric oxides. The oxide scale was composed of Cr2O3 type. The Cr/Ni ratio in the oxide scale at 700°C was by one order larger than that at 650°C. The oxidation resistance of Ni alloys is maintained by a uniform Cr2O3 layer which is composed of high Cr content.
Lattice-Based Walks and the Monte Carlo Method for Addressing Mass, Thermal and Elasticity Problems
Authors: Belova Irina V. , Murch Graeme E. , Fiedler Thomas , Öchsner Andreas
Published: March 2009

In this paper, we review the recent developed method based around lattice-based random walks and the Monte Carlo method. This method, which is now called the Lattice Monte Carlo method, permits complex phenomenological problems in diffusion, thermal conductivity and elasticity to be addressed. It is shown how the effective mass diffusivity, thermal diffusivity/thermal conductivity and the bulk modulus in composites can be calculated and also how concentration profiles and temperature profiles can be determined in situations where the diffusivity depends on position and concentration and the thermal conductivity depends on position and temperature respectively.
Short Order and Hydrogen Transport in Amorphous Palladium Materials
Authors: Pastukhov E.A. , Sidorov N.I. , Polukhin Valery A. , Chentsov V.P.
Published: March 2009

Molecular dynamics simulation was used for investigating hydrogen migration in Pd-Si alloy at a temperature Т = 300 K. The strong affect of hydrogen dynamics and its defects creation to structure of palladium matrix is stated. The partial radial distribution function calculation for silicon specifies a preferable arrangement of silicon atoms relative to each other in the second coordination sphere. Model calculations have shown that not only silicon atoms can affect hydrogen mobility. Hydrogen itself also can significantly change the diffusion of the other components in the alloy.
An Analytical Study on the Spherical Spindle of an Ultra Precision Machine for Use in Nano Machining Technology
Authors: Vahdati Mehrdad , Shokuhfar Ali
Published: March 2009

Air spindles in ultra precision machines produce rotational movements for the cutting tool or work piece. The common combination of a simple cylindrical rotor and stator is the design for most spindles. If the length of such a spindle is longer than usual, it will deviate from its stable situation and start vibrating during operation, especially in high rotational speeds. In order to overcome the vibration problem, one of possible solutions is the application of a spherical rotor and stator. The manufacturing and assembly limitations do not allow obeying the spherical shape exactly. Thus, the design has been committed according to a quasi-sphere. This form of the rotor will be more stable. The subsequent result of stability improvement will be less air pressure and power consumption. There are some specific characterizations of the spindle which must be calculated for the spherical case. For this purpose a computer model of the object was made. Then, the model was put under finite element study to find the best air pressure and air flow velocity condition.
Surface Composition and Diffusion in Catalysts Probed by PFG NMR Techniques
Authors: Weber D. , Mantle M.D. , Sederman A.J. , Gladden L.F.
Published: March 2009

We have recently developed an experimental protocol to study surface self-diffusion using Pulsed Field Gradient (PFG) Nuclear Magnetic Resonance (NMR) techniques. While the study of diffusion phenomena with PFG NMR techniques evolved in the 1960s and is nowadays part of the standard NMR toolbox, our novel approach allows us the simultaneous quantification of diffusion coefficients of molecules in a surface layer and the bulk pore liquid of a porous medium. This is of relevance when attempting to explain solvent effects in catalysis. Solvent effects are known to have a significant impact on catalyst performance. For example, water has been reported to influence the reaction rates during carbonyl hydrogenations. In this work we have assessed the effect of two solvents – water and isopropyl alcohol (IPA) - on the bulk pore and surface diffusivity of methyl ethyl ketone (MEK) in porous Ru/SiO2 catalyst pellets. We find that when MEK is dissolved in water, it appears to interact more closely with the surface than when it is dissolved in IPA.
Early Stage of Solid State Interfacial Reaction between Copper and Tin
Authors: Maeda Masakatsu , Inoue Naoto , Sato Takaaki , Takahashi Yasuo
Published: March 2009

High-purity plates of Cu and Sn were diffusion bonded to clarify the early stage of the solid state interfacial reaction between Cu and Sn, focusing on the incubation time for the formation of intermetallic compounds. A clear incubation time for the formation of intermetallic compounds is observed at every temperature between 423 and 493 K. The incubation time changes depending on the annealing temperature. The interface annealed at 423 K for 3.60 ks maintains the direct interconnection between Cu and Sn being free of intermetallic compounds. The exposure of Cu surface to air affects the interfacial reaction. Annealing of the Cu/Sn interface at 493 K for 3600 s starts to form voids by using the Cu plates exposed for 8.64×104 s or longer to air. Furthermore, the reaction product layer formed by the same annealing condition becomes thinner when the Cu plates exposed for 8.64×105 s or longer to air are used.
A Numerical Study of Decoupled Bubble Dynamics in Nucleate Boiling
Authors: Sajid Muhammad , Bennacer Rachid
Published: March 2009

Nucleate boiling is an efficient mechanism of heat transfer. The rate of bubble growth and the subsequent bubble motion has a tremendous influence on heat transfer. The study of bubble dynamics is a coupled problem. The rate of evaporation controls the interface speed. One approach to study bubble dynamics is to decouple the problem from energy conservation equation and use an input value of rate of evaporation. The objective is to observe how irregular evaporation rate controls bubble dynamics and the shape of bubble and to study the local over-pressure. The level set method is used to track the liquid-vapor interface. The model consists of the Navier-Stokes equations which govern the momentum and mass balances and the level set equation which governs the interface motion due to phase change. The dynamics of a single bubble under different rates of evaporation and varying levels of gravity have been studied. The results of the numerical simulation show that this model adequately describes bubble dynamics in nucleate boiling, including conditions of microgravity.
Problem of the Variability of Substitute Thermo-Physical Properties for Heat Transfer Modelling in Iso- and Iso-Exo Porous Materials
Authors: Ignaszak Zenon , Popielarski Paweł
Published: March 2009

In foundry technology the modeling of heat transfer in materials containing exothermic components must take into consideration the presence of heat sources in the Fourier–Kirchhoff equation. The aim of this investigation was the identification of real and effective thermophysical parameters of the insulating and insulating –exothermic materials used as riser sleeves containing these exothermic heat sources. The experiments of liquid steel or cast iron pouring into the mould, containing different insulating and exothermic sleeves were carried out, using thermocouples meas-urement systems (thermal analysis of casting–mould system). Then the thermo-physical coefficients of these materials were calculated using inverse problem solution. The numerical system Calcosoft and its Inverse Solution procedure were applied.
Macroscopic and Microscopic Effects in Diffusion and Reaction in Catalyst Porous Particles
Authors: Martins António , Braga Carlos H. , Mata Teresa M.
Published: March 2009

This article presents and discusses a network model to describe and predict the behaviour and performance of catalyst particles. The differences and advantages of this approach when compared to the continuous models currently used in practice are highlighted and critically assessed. The local structure of the catalyst particle is modelled using a three dimensional network model made up of cylindrical pores and nodes of negligible volume. In the pores a homogenous first-order reaction takes place, coupled with the diffusion. For steady state conditions the concentration field can be obtained solving a sparse linear system of equations, obtained by solving the mass balance equations written for the network nodes and using the concentration profile in the network pores. The influence of the boundary conditions and the network sizes was investigated, showing the results in particular that the nature of the boundary conditions can have a profound impact in the predictions of the model.
Numerical Analysis for the Behavior of Multiple Markers in Multiple Phase Diffusion Couples
Authors: Shimozaki Toshitada , Okino Takahisa , Lee C.G.
Published: March 2009

The movement of multiple markers (M-M) embedded in a multiple phases diffusion couple (M-couple) has been numerically analyzed for binary two phases models taking the molar volume change effect to the diffusion direction into account. From the results obtained by this analysis the places where vacancies are annihilated or generated can be visualized. It has been clarified that a part of M-M is necessarily shown by a linear line due to parabolic movement of the inter-phase interface. Some other interesting results obtained in this study will be reported.
Characterisation by EBSD of Cold Rolled High-Silicon Steel
Authors: Rodriguez-Calvillo Pablo , Schneider Juergen , Houbaert Yvan
Published: March 2009

Steel containing a high Si-content is mainly used as electrical steel in flux carrying electrical machines. These materials are divided in the categories: grain oriented and non oriented electrical steels, mainly used in transformers and electrical motors, respectively. Their industrial production is normally limited to silicon contents lower than 3.5 m.-%, due to the generation of brittle ordered structures if the Si content is increased beyond this value.
The paper reports on microstructure and texture evolution during processing by rolling of electrical steel in the high Si-range. The materials studied are two industrial electrical steels with a silicon content of 2.4 and 3.2 m.-%, their situation was as-received after hot rolling and industrial annealing. The different processing parameters, as rolling temperatures and cooling conditions have a strong influence on the final microstructures and textures. The importance of hot rolling and intermediate annealing processes is enhanced since above 2 m.-% Si these steels do not experience the usual α-γ-α phase transformation, because they present a bcc crystal structure over the entire solidus domain. Consequently, their microstructures and textures are strongly inherited from the earlier processing steps into the final product.
The as-received materials were cold rolled with a nominal reduction of 75%. Their microstructures and textures were analysed by EBSD. The results obtained were compared with those of the industrial hot band. The textures were studied by the interpretation of the most important crystallographic fibre textures, extracted from the ODF’s of φ2 = 45o section of the Euler space. Special attention was given to the evolution of the most important magnetic textural components. Although in terms of grain shape, IQ, texture and normalised thickness position or ‘s’-parameter the microstructures obtained before and after cold rolling are totally different, the overall crystallographic textures seem not to differ very much.
Reduction Kinetics of Iron Ore Materials by Gases
Authors: Dmitriev A.N. , Chesnokov Yu.A.
Published: March 2009

The proposed balance logic-statistical model of the blast furnace process is based on the use of material and thermal balances along with calculations of heat- and mass exchange taking into account the non-uniformity of gas and burden distribution on the radius of the furnace and influence of the basic metallurgical characteristics of iron ore raw materials and coke on the indices of blast furnace operation. As a check of the applicability of the model, calculations on the most critical parameters of the blast furnace process – the smelting of ferromanganese and iron nickel with a graphical representation of heat- and mass exchange processes, dynamics of oxides reduction on the height and radius of the blast furnace have been carried out.
The Influence of Milling Time and Impact Force on the Mutual Diffusion of Al and Cu during Synthesis of Al-4.5wt%Cu Alloy via Mechanical Alloying
Authors: Mostaed Ali , Mostaed Ehsan , Shokuhfar Ali , Saghafian H. , Rezaie Hamid Reza
Published: March 2009

The study of mechanical alloying (MA) process on the immiscible Al–Cu systems having positive heats of mixing has been investigated by the earlier researchers. However, a comprehensive understanding of the diffusion phenomenon during the mechanical alloying process is still far from complete. The effects of milling time and impact force, defined as the ball-to-powder weight ratio (BPR), on the elemental diffusion during mechanical alloying process of Al-4.5wt%Cu were evaluated in the current work. X-ray diffraction results showed that increasing the milling time and impact force led to increasing the dislocation as because of increasing the micro-strain, lattice parameter and decreasing the crystallite size. As a result of this, the diffusion rate was enhanced. The interpretation of data resulted have been discussed in details.
Thermo-Mechanical Coupled Problems at Finite Strains
Authors: Vaz M. , Muñoz-Rojas Pablo A. , Lange M.R. , Stahlschmidt J.
Published: March 2009

This paper discusses some thermodynamic aspects in association with a large strain/large displacement elastic-plastic formulation aiming at application to metal forming problems. The mechanical solution adopts the multiplicative decomposition of the gradient of deformation into elastic, plastic and thermal components. The approach is illustrated by analysing the thermal effects in the plastic deformation of low-carbon steel specimens subject to tensile loading.
Gas Diffusion and Re-Diffusion in Polyethylene Foams
Authors: Escudero J. , Lázaro J. , Solórzano E. , Rodríguez-Pérez Miguel A. , de Saja Jose A.
Published: March 2009

In this work, the effective diffusion coefficient of the gas contained in closed cell polyethylene foams under static loading is measured. To do this, compressive creep experiments were performed on low density polyethylene foams produced under a gas diffusion process. Density dependence of this coefficient has been analysed as well as the variation of pressure with time inside the cells. Finally, immediately after compressive creep, the recovery behaviour of the foams was also characterised. Different abilities for recovering were observed depending on the density of the foam and the absolute recovery resulted independent of the initial stress applied.
Experimental Studies of Kiwi and Pear Fruit in Ice-Temperature Storage
Authors: Liu Bin , Jiang Shen , Guo Ya Li , Bennacer Rachid
Published: March 2009

The ice-temperature storage is one of the most important methods in the preservation of fresh fruits and vegetables, while the theory about ice-temperature storage is still not mature at present. In order to study the effect of the pre-thermal processes and the post-thermal processes on the ice-temperature storage, some experiments were carried out. The experimental conditions included two different cooling rates (5°C/day and 3.5°C /day) and two different heating rates (3.2°C /day and 5.1°C/day). After the cooling, the cooled Kiwi and Pear had been stored in the ice-temperature storage for one month. During the storing time, the total sugar, the acidity and the soluble solid were measured by the national standards each two weeks. The present obtained results show that a lower cooling rate would be beneficial for sustaining hydrocarbons and increasing the acidity in fruits after ice-temperature storage; while a quicker cooling rate would increase the soluble solid in fruits after ice-temperature storage.
Structure and Properties of Grain Boundaries in Submicrocrystalline W Obtained by Severe Plastic Deformation
Authors: Popov Vladimir V. , Valiev Ruslan , Popova E.N. , Sergeev A.V. , Stolbovsky A.V. , Kazihanov V.U.
Published: March 2009

Submicrocrystalline structure of W obtained by severe plastic deformation (SPD) by high pressure torsion (5 revolutions of anvils at 4000C) and its thermal stability have been examined by TEM. Grain boundaries of submicrocrystalline W have been studied by the method of the emission Mössbauer spectroscopy in the initial state and after annealing at 400-6000С.
Grain Boundary Diffusion and Segregation of Co and Cr in Zr-Based Alloys
Authors: Corvalán Moya C. , Iribarren Manuel J. , Di Lalla Nicolás , Dyment Fanny
Published: March 2009

51Cr and 60Co diffusion along grain boundary (GB) in polycrystalline Zr and -Zr-20%Nb were measured by means of the radiotracer technique in an overall temperature range [380-1000] K. The use of Harrison´s C and B kinetics resulted in direct data of the GB diffusivity (Dgb) and the apparent GB diffusivity (Pgb). The analyzed temperatures involved those of power reactors service. The GB segregation factors s were determined or evaluated in the limit of very dilute solute concentration.
Measurement of Fracture Toughness in AISI 1018 Borided Steels by Vickers Indentation
Authors: Campos-Silva Ivan , López-Perrusquia N. , Ortíz-Domínguez M. , Figueroa-López U. , Hernández-Sánchez E.
Published: March 2009

This study evaluates the fracture toughness of Fe2B boride layers formed by the paste boriding thermochemical process on an AISI 1018 steel surface. The samples were placed in acrylic molds for the impregnation of boron carbide paste with thickness of 4mm over the sample surfaces to produce the diffusion into the steel. The aforementioned treatment considered one temperature, T= 1273 K, and three exposure times t=5, 6 and 8 h. Later, the borided samples were prepared metallographically to determine the mean values of the layer thicknesses and to produce Vickers microindentations at 45 m from the surface, applying four loads (1.9, 2.9, 4.9 and 9.8 N). The microcracks generated at the corners of the Vickers microindentation were considered as experimental parameters, which are introduced into two Palmqvist cracks models to determine their corresponding fracture toughness KC. As a result, the experimental parameters, such as exposure time and applied load are compared with the resulting fracture toughness of the borided phase.
Selective Laser Sintering of Poly(L-Lactide) Porous Scaffolds for Bone Tissue Engineering
Authors: Lee S.H. , Zhou Wen You , Wang Min , Cheung W.L. , Ip W.Y.
Published: March 2009

The aim of this study was to investigate the feasibility of utilizing selective laser sintering
(SLS) to build 3D porous tissue engineering scaffolds from small quantities of poly(L-lactide)
(PLLA). PLLA microspheres with suitable particle sizes for the SLS process were produced by the
oil-in-water emulsion solvent evaporation technique. A miniature build platform was designed,
fabricated and incorporated in an existing Sinterstation® 2000 system to enable small quantities of
polymer powder to be used for the production of 3D porous scaffolds. Trial runs were first performed
using the DuraForm™ polyamide powder and interfacing problems between the miniature build
platform and the existing machine were solved. Then 3D porous scaffolds were successfully built
from the PLLA microspheres using the modified SLS machine. This study paved the way for further
comprehensive studies on selective laser sintering of tissue engineering scaffolds using expensive
biopolymers and their composites.