bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Aging Behavior of Al-0.2wt%Zr Alloy Heavily Deformed by ARB Process
Authors: Sato Takatoshi , Terada Daisuke , Tsuji Nobuhiro
Published: March 2009

An Al-0.2wt%Zr alloy was severely deformed up to a strain of 8.0 by accumulative roll
bonding (ARB) process, started from the solution-treated state. The microstructural evolution during
ARB and its aging behavior were investigated. With increasing the number of ARB cycles, Vickers
hardness of the specimens increased and reached to a constant value. The microstructural evolution
during the ARB could be understood in terms of grain subdivision. The ultrafine grained (UFG)
materials whose mean grain size was 0.4 -m were obtained by 10-cycle ARB process. In aging of the
ARB processed specimens at high temperatures above 673K, the UFG microstructures quickly
coarsened. On the other hand, it was suggested that the precipitation behaviors of the ARB specimen
at 623K were quite unique and completely different from those of the conventionally solution-treated
material with coarse grain size.
Study of a Fine-Grained AZ31 Magnesium Alloy Prepared by Equal Channel Angular Pressing
Authors: Yang Su Yuan , Liu Jian Ming , Wang Lu , Cai Hong Nian , Wang Fu Chi , Yu Yue Guang
Published: March 2009

A fine-grained magnesium alloy AZ31was obtained through equal channel angular
pressing (ECAP).Mechanical properties and the microstructures after deformation under tension
and compression were investigated. The tensile strength, compressive strength and the elongation to
failure of the fine-grained AZ31 are enhanced due to the reduction of grain size. The compressive
ultimate strain (CUS) of the fine-grained AZ31 magnesium alloy is lower than that of the initial
state due to the formation of shear bands during compression. The ECAP processed AZ31
magnesium alloy exhibited no tension/compression asymmetry in yielding.
Crystallographic Texture Development in CP Ti Subjected to ECAP
Authors: Alexandrov Igor V. , Sitdikov Vil D.
Published: March 2009

In this article we present the results of the experimental research and those of the
processes developing the crystallographic texture of computer modeling in CP Ti in the process of
1-4 equal channel angular pressing (ECAP) passes along the route ВС. The goal of the research was
to determine the active deformation mechanisms, depending on the strain degree, accumulated in
the ECAP process. The research was carried out by the method of X-ray analysis and by computer
modeling. Computer modeling was carried out on the example of visco-plastic self-consistent
model. Thereby, the basal, the prismatic and the pyramidal (of the 1st and of the 2nd order) slip
systems were considered as possible active slip systems. Besides, the possibility of activating the
tensile and the compressive twinning systems were taken into consideration. As the result of the
carried out experimental research, the objective laws of forming preferred orientations were
determined. For the first time, with the help of computer modeling, made up to the 4th ECAP pass, it
was shown that the crystallographic texture development processes in CP Ti in ECAP, realized at
temperature of 723 K, can be explained by activation of the basal, prismatic and pyramidal (of the
1st order) slip systems and compressive twinning systems. Therefore, the increase of the ECAP
passes can lead to amplification of contribution of the basal and prismatic slip systems, as well as
the insignificant weakening of the contribution of pyramidal slip systems (of the 1st order).
Moreover, the compressive twinning can become obvious only in the 1st ECAP pass.
Susceptibility to Stress Corrosion Cracking in Ammonia of Nanostructured Cu-10wt%Zn Alloy Produced by Severe Plastic Deformation
Authors: Miyamoto Hiroyuki , Vinogradov Alexei , Hashimoto Satoshi
Published: March 2009

In this study, susceptibility to SCC of nanostructured Cu-10wt%Zn alloys, produced by
equal-channel angular pressing (ECAP) was investigated under the constant stress test in ammonia
vapour, which has been well-known typical environment for IGSCC of Cu-Zn alloy. Billets having
diameter of 20 mm and length of 100 mm were subjected to ECAP for eight passes at room
temperature to obtain structure with grain size of about 100 nm. After ECAP, some of the billets were
flush-annealed in 473 K for 60 seconds to decrease excessive unequilibrium dislocations at grain
boundaries. Coarse grained specimens without ECAP and one-pass specimens were also tested for
comparison. The specimens for SCC were tensioned by a constant load in ammonia vapour inside a
glass chamber for 24 hours at room temperature. After the SCC tests, maximum length of cracks was
evaluated by SEM. Specimen having UFG structure by 8-passes exhibited cracks in lower applied
stress ratio, (=σa/σys) compared with 0- and 1-pass samples, where σa is applied stress and σys is yield
stress, respectively. Most importantly, the specimen with annealed at 473K for 60s after ECAP
cracked in higher applied stress. It became less sensitive to SCC after flush annealing although
mechanical properties were not changed considerably. In our previous studies, we reported that the
SCC of UFG copper produced by ECAP, and the sensitivity to SCC becomes lower by flush annealing.
Results are discussed in terms of grain boundary state with or without extrinsic grain boundary
dislocations
Characteristic Features and Thermal Stability of Molybdenum Processed by Different Ways of Severe Plastic Deformation
Authors: Ivanov Konstantin V.
Published: March 2009

Characteristic features and thermal stability of the structure of molybdenum processed by
high pressure torsion, equal-channel angular pressing or multy-step forging have been investigated
using transmission electron microscopy, X-ray diffraction analysis and orientation imaging
microscopy. The structural factors responsible for the strengthening and thermal stability of
molybdenum processed have been obtained. It has been demonstrated that only high pressure
torsion is an effective method to refine molybdenum structure (down to 0.2 µm). Recrystallization
occurs during the others investigated processing disabling significant grain size reduction.
Tailoring the Magnetic Properties of Ferritic Alloys by HPT
Authors: Scheriau Stephan , Rumpf K. , Kleber Siegfried , Pippan Reinhard
Published: March 2009

Industrial available FeSi, FeCo and FeNi alloys with an initial grain size of 20-50 m were
subjected to Severe Plastic Deformation (SPD) up to strain levels where a saturation of the
microstructural refinement is observed. For both SPD conditions, ambient temperature (293 K) and
liquid nitrogen temperature (77 K), the microstructure of the severely deformed state is analysed by
Back Scattered Electrons (BSE) micrographs captured in a SEM. Additionally, samples that were
deformed at 77 K are examined in a Transmission Electron Microscope (TEM). The magnetic
properties were characterised by means of SQUID-magnetography providing information about the
magnetization behaviour of the material in the as-processed state. Depending on the SPD conditions
the mean microstructural sizes in the steady state are about 100-150 nm and 30-80 nm at 293 K and
77 K, respectively. The small microstructural sizes influence significantly the magnetic properties
of these ferritic alloys. The initial soft-magnetic behaviour of the coarse grained state shifts towards
a hard-magnetic with decreasing crystallite size. For crystallite sizes smaller than ~80 nm the
magnetic properties become again more soft-magnetic. The experiments show that very low
coercitivity can be obtained by SPD if the grain size is smaller than ~50 nm.
High Strength Bulk Nanostructured 2219 Al Alloy Produced by High Energy Ball Milling and Hot Pressing
Authors: Shanmugasundaram T. , Subramanya Sarma V. , Murty B.S. , Heilmaier Martin
Published: March 2009

The microstructure and mechanical properties of nano-crystalline 2219 Al alloy (Al-6.4Cu-0.29Mn,
all in wt %) was studied. Nanocrystalline powders were produced from gas atomized 2219 Al alloy
powders by high energy ball milling at room temperature. Powders were collected at different
milling times and X-ray diffraction (XRD) analysis was used to evaluate grain size. High Vickers
hardness (250HV), high compressive strength (920 MPa) and low ductility (2%) were observed in
unimodal bulk nanostructured 2219 Al alloys consolidated to 99% density by hot pressing (HP). In
addition, these nanocrystalline powders were blended with 15, 30 and 50% of (gas atomized)
coarse-grained powders to obtain balanced mechanical properties of enhanced yield and ultimate
strength and reasonable ductility and toughness as compared to either conventional or
nanocrystalline 2219 alloys.
Effect of La2O3-Rich Glass Addition on Sintering of Zirconia Based Ceramics
Authors: dos Santos Claudinei , Souza R.C. , Fernandes Maria Helena F.V. , Almeida Nuno A.F. , Almeida Flávia A. , Silva Rui F.
Published: March 2009

In this study, the influence of La-rich glass addition and sintering conditions on the
densification and mechanical properties of 3 mol.%Y2O3-stabilized tetragonal zirconia polycrystals
(3Y-TZP) ceramics were evaluated. High-purity tetragonal ZrO2 powder stabilized with 3 mol.%
Y2O3 and La2O3-Rich glass were used as starting powders. Two compositions, ZrO2 containing 5
and 10 wt.% of a La2O3-rich glass were studied in this work. The starting powders were
mixed/milled by planetary milling, dried at 90°C for 24 hours, sieved through a 60 mesh screen and
uniaxially cold pressed under 80 MPa. The samples were sintered in air at 1200, 1300 and 1400°C
for 60min, and at 1450°C for 120min, with heating and cooling rates of 10°C/min. Sintered samples
were characterized by relative density, X-ray diffraction (XRD) and Scanning Electron Microscopy
(SEM). The mechanical properties, hardness and fracture toughness, were obtained by Vickers
indentation method. Dense sintered samples were obtained for all conditions. Samples sintered at
1300°C for 60 min presented the optimal mechanical properties with hardness of 1170 kgf.mm-2 and
fracture toughness of 8.3 MPam1/2.
Study of Inelastic Light Scattering in LaxSr(1-1.5x)TiO3
Authors: Almeida A. , Correia Tatiana M. , Chaves M.R. , Vilarinho Paula M. , Kholkin Andréi L.
Published: March 2009

In an attempt to gain a better understanding of the lattice dynamics in lanthanum doped
SrTiO3 (STO) ceramics, with general formulae LaxSr(1-1.5x)TiO3, we have carried out a detailed
Raman study of the x=0.0133 ceramic in the temperatures ranging from 10K to room temperature.
Our results show that lanthanum substitution gives rise to new features in the Raman spectra. The
Rayleigh band and the extra Raman-forbidden infrared active modes observed provide evidence for
the existence of disorder in the system, apparently associated with grain structure, and lattice
defects. Moreover, the absence of a TO1 polar soft mode supports the non-existence of a
ferroelectric phase at low temperatures. The shift of the para-antiferrodistorsive transition
temperature towards higher temperatures clearly evidences that the replacement of Strontium by
Lanthanum occurs at the lattice A-site.
Elastic Behaviour of Spherical Particles Reinforced Metal-Matrix Composites
Authors: Botas José D. , Velhinho Alexandre , Silva Rui Jorge C.
Published: March 2009

Current technology provides means of fabrication of spherical micro-particles, either
hollow or compact, for all engineering materials. Such spherical particles can be further embedded
into another material to build-up either random dispersions or close-packed arrays, according to the
production route and the degree of anisotropy intended for the ultimate composite material. In this
study, a simple analytical formula for the composite stiffness is derived from an early
micromechanics model, to describe the actual reinforcement of ductile matrices by a random
dispersion of uniform spherical ceramic particles. Predictions from this model are checked against
some other relevant models, and specific features arising from its theoretical derivation are pointed
out.
Production of Bioactive Nano-Hydroxyapatite/Polysaccharide Composites for Bone Tissue Engineering
Authors: Daniel-da-Silva Ana L. , Gil A.M. , Correia Rui N.
Published: March 2009

Porous κ-carrageenan based composites with potential application in bone tissue
engineering have been prepared by in situ co-precipitation of nanoparticles of calcium phosphates,
followed by thermally induced gelification and freeze-drying. The scaffolds showed macroporous
structure with interconnected porosity. The variation of the biopolymer concentration affected the
microstructure and compressive mechanical performance of the composites. The in vitro bioactivity
was assessed by soaking the composites in simulated body fluid (SBF) and the formation of an
apatite layer on their surface was found.
Study of Inhomogeneities in Non-Magnetic Tubes by Means of a Contactless Inductive Technique
Authors: Íñiguez J. , Raposo V. , Hernández-Gómez Pablo
Published: March 2009

An accurate technique for contact-less measurement of resistivity in non-magnetic
conductive tubes has been developed. It is intended for application in non-destructive testing (NDT)
in tube manufacturing by simple study of the induced currents. Inhomogeneities or minimal
imperfections in the tube thickness are immediately detected. This measuring technique is also
suitable for determining the thickness of very thin metal coatings on non-conductive tubes. The
experimental setup corresponds to an electrical transformer, the tube being the core. A first coil is
placed around the tube under test, whereas the detecting coil is placed inside it. The study of the
magnetic screening caused by the currents induced in the tube, allows its conductivity to be
determined. The use of low frequency guarantees the almost complete absence of the skin effect in
such a way that the results are obtained in a very simple manner. The method is based on the
determination of the phase angle of the complex mutual inductance between the two coils working
under low frequency conditions.
Rheology of Chitosan and Genipin Solutions
Authors: Moura M.J. , Figueiredo M.M. , Gil M. Helena
Published: March 2009

This paper investigates the rheological behaviour of chitosan solutions crosslinked with
different concentrations of genipin at body temperature and physiological pH. The effect of the
crosslinker concentration on the rheological properties of hydrogels was evaluated. The oscillatory
time sweep was used to analyze the dynamics of G’ during in situ gelation experiments enabling the
determination of the gelation time. Additionally, the stress and frequency sweeps were employed to
measure G’ of cured hydrogels. The solutions of chitosan crosslinked with genipin at physiological
conditions were found to form relatively strong elastic gels for all the concentrations, when
compared to pure chitosan. A significant reduction on gelation time was achieved. This behaviour
shows that these formulations are able to be produced in situ and thus constitute promising matrices
for cells and bioactive molecules encapsulation.
Influence of Si-Al-Ge-Sb Matricies on Tm3+ Excitation Levels
Authors: Pospíšilová M. , Adámek P. , Peterka P. , Kubeček V. , Kašík I. , Matějec V.
Published: March 2009

Absorption and fluorescence spectra in the range from 350 to 1750 nm of several Tm3+-
doped optical performs (rods) for optical fiber drawing were measured. Silica-based matrices of
Al2O3-GeO2-P2O5-Sb2O3-SiO2 composition doped with several thousands ppm of Tm3+ were
characterized. The preforms were fabricated by the Modified Chemical Vapor Deposition and by
the solution doping methods. A new method, Genetic Algorithm SPEctra Decomposition was
adopted for processing of the measured absorption spectra. This decomposition made it possible to
calculate the oscillator strengths of Tm3+ absorption levels. Fluorescence bands of Tm3+ at 800 nm
or 1640 nm were found in fluorescence spectra measured on the preform samples when excited at
1064 nm only.
Magnetic Field Enhancement with Soft Magnetic Flux Guides
Authors: Leitão D.C. , Trindade I.G. , Fermento R. , Araújo João P. , Cardoso S. , Freitas P.P. , Sousa João Bessa
Published: March 2009

In this work, a study of the sensitivity enhancement of spin valve sensors, when located
in close proximity to magnetic flux guides, is presented. The magnetoresistance (MR) of spin-valve
sensors, lithographically patterned into stripes with lateral dimensions, (length) l = 500 µm, (width)
wsensor = 1, 2, 6 µm and placed near one/two Co93.5Zr2.8Nb3.7 (CZN) magnetic flux guide, is
characterized at room temperature. CZN has a high permeability that together with a defined
microstructured shape, is able to concentrate the magnetic flux in a small area, leading to an
increase in sensor's sensitivity. The magnetic field amplification is estimated by comparison of
sensor sensitivity with/without magnetic flux guides, in the linear operation range, and studied as a
function of different parameters. Besides an enhancement in sensitivity, sensors also exhibit an
important increase in the hard axis coercivity and a shift from MR(H=0) = 0.5, both attributed to the
magnetic flux guides. Amplification factors of the order of 20 are observed..
Transport Properties in All Oxide Magnetic Multilayers
Authors: Sobreiro H. , Berini B. , Keller N. , Schmool David S.
Published: March 2009

The all oxide magnetic multilayer system [LaNiO3/SmFeO3]n (for n = 1 and 2), grown on
single crystal SrTiO3(100) substrates, has been produced using the laser MBE (Molecular Beam
Epitaxy) technique. We have made a systematic study of the electrical transport properties in the
temperature range from 15–300K. As part of this work, we have made a detailed study of the
metallic properties of the LaNiO3 layer as a function of the oxygen partial pressure (pO2) and
substrate temperature (TS). We have measured magnetic layers of SmFeO3 with LaNiO3 electrodes
as a function of the magnetic layer thickness (10 – 470 nm). A non-metallic behaviour is observed
with evidence of a “hopping” mechanism at low temperatures. For the n = 2 multilayers, we have
measured the temperature dependence of resistance for the sample series with varying LaNiO3
interlayer thickness (t = 2 – 30 nm). We observe an appreciable increase of the low temperature
resistance for the interlayer thicknesses between 3.75 – 7.5 nm. This could indicate a change in
coupling from ferromagnetic to antiferromagnetic between the magnetic layers.
Contrasting Morphology of Calcium Phosphate Powders Prepared by the Wet Method Using Poly (Ethylene Glycol)
Authors: Dias Susana , Lourenço Vera , Nogueira Carlos A. , Oliveira Fernando A. Costa
Published: March 2009

When preparing β-tricalcium phosphate (β-TCP), it is difficult to industrialise traditional
methods because of the problem of particle aggregation. In this paper, β-TCP was prepared by
calcining calcium-deficient hydroxyapatite (CDHA) powders obtained by the wet precipitation
method at pH=6 and 40 °C, together with additions of poly (ethylene glycol) (PEG), in order to
prevent powder agglomeration. The effect of the Ca/PEG mass ratio on the particle size distribution
and the morphology of the resulting powders was evaluated. For comparison purposes, one powder
without PEG addition was also synthesized. All synthesized powders were characterized by means
of X-ray diffraction analysis, particle size analysis and scanning electron microscopy prior and after
calcination in static air at 1000 °C for 15 h. Single-phase β-TCP powders have been obtained by
calcining CDHA powders in the temperature range of 850°C-1150°C. It was also found that
increasing the PEG content in solution decreased the particle size distribution of the agglomerated
particles and the β→α-TCP transition temperature. A plausible explanation consistent with these
experimental findings is proposed.
Corrosion Resistances of As-Cast and Quenched Samples of a Zn-22Al Eutectoid Alloy
Authors: Osório Wislei R.R. , Cheung Noé , Garcia Leonardo R. , Garcia Amauri
Published: March 2009

To address the increasing demand for high performance and high quality die castings,
Zn-Al casting alloys have been developed, in particular for applications in the automotive industry.
This family of alloys has good physical, mechanical and tribological properties and is commonly
used as foundry alloys in a variety of applications. Particularly, the Zn-22 wt% Al eutectoid alloy is
a classic commercial material and a fine-grained structure can be obtained by using a suitable heat
treatment which can induce a superplastic behavior. On the other hand, this heat treatment can
affect the corrosion behavior of such alloy. The present work focuses on the influence of as-cast and
quenched microstructures of the Zn-22wt%Al eutectoid alloy on its electrochemical corrosion
behavior. The typical microstructural patterns were examined by using optical microscopy
techniques. In order to evaluate the corrosion behavior of such alloy, corrosion tests were performed
in a 0.5 M NaCl solution at 25°C by using an electrochemical impedance spectroscopy (EIS)
technique and potentiodynamic polarization curves. An equivalent circuit by using the ZView
software was also used to provide quantitative support for the discussions and understanding of the
electrochemical corrosion behavior. It was found that the heat-treated samples are more susceptible
to the corrosion action than the as-cast alloy sample.
Effect of Intermetallics on the Corrosion of Al 2024-T3 Alloy in Solutions with Different Chloride Concentration
Authors: Queiroz F.M. , De Melo Hercílio G. , Costa Isolda
Published: March 2009

Al 2024-T3 is an important alloy very prone to localized corrosion. In this investigation
the effect of chloride concentration on the corrosion resistance of the Al 2024-T3 alloy has been
studied, focusing on the dissolution of the intermetallics (IMCs). Sodium chloride solutions of two
concentrations, 0.6 M and 0.01mM, were used as test electrolytes. During the investigation selected
regions of polished samples had their IMCs analyzed by Scanning Electron Microscopy (SEM) and
X-ray Energy Analysis (EDX) prior and after different immersion times in the two test electrolytes.
The results showed that even in the lowest chloride concentration the electrolyte was highly
corrosive to the Al-Cu-Mg IMCs leading to their partial dissolution and to the attack of the
surrounding matrix after only one hour of immersion. On the other hand, the corrosion behavior of
the Al-Cu-Mn-Fe IMCs was random, and no correlation could be established between corrosive
attack and chloride concentration or time of immersion for this type of particle. Atomic Force
Microscopy (AFM) analyses have indicated a stronger dissolution of the matrix in the more
concentrated electrolyte. This seems to lead to a milder attack of the IMCs in this solution when
compared to the less concentrated one, as indicated in the SEM images.
Hardness and Young´s Modulus Determination of Nanostructured Alumina-Titania Coatings
Authors: Rico Álvaro , Garrido-Maneiro Miguel Ángel , Salazar Alicia , Otero Enrique , Rodríguez J.
Published: March 2009

It has been generally accepted that a nanostructured material exhibits better properties
than conventional ones. Nanostructured ceramic coatings fabricated by plasma spray have been
developed for a wide variety of applications where a surface protection is required. Alumina -
titania coatings are usually used as protective layers in many industrial applications requiring a high
wear resistance during dry sliding contact. In this work, nanostructured and conventional Al2O3 –
13% TiO2 coatings deposited via atmospheric plasma spray were compared. Mechanical
characterization was carried out using depth sensing indentation to determine hardness and Young´s
modulus of the coatings. Size independent properties can be determined after considering
geometrical factors such as tip rounding and indenter deformation. Nanostructured coatings show
slightly better mechanical properties than conventional coatings.
Design and Optimisation of a Blow Moulded Container
Authors: Faria R.P. , Carneiro Olga S. , Nóbrega João M. , Ritto M.K.
Published: March 2009

This work is focused on the first step of the extrusion blow moulding process as part of a
global optimisation process encompassing several steps: optimisation of the part thickness,
optimisation of the parison thickness that will guarantee the specified thickness profile and
optimisation of the extrusion conditions (namely, the sequence of the die mandrel movements)
required to obtain the optimal parison thickness distribution. A high density polyethylene (HDPE)
extrusion blow moulded tamper evident container was studied using a finite element based analysis
(FEA) in order to determine the optimized thickness distribution required for the blown part,
considering its mechanical specifications. Several tests corresponding to the requirements for UN
homologation for dangerous substances transportation were performed using a commercial
software. Non-linear models were used to better describe the mechanical part behaviour. The results
obtained at this stage were used to redesign the blown part. In future work this optimised design
will be used as an input for optimising the subsequent stages.
In Situ X-Ray Characterization of Isotactic Polypropylene: Dependence of the Crystalline Properties on the Draw Down Ratio
Authors: Lopes Paulo E. , Pennington William T. , Ellison Michael S.
Published: March 2009

Polymer crystalline regions can be characterized by wide-angle X-ray scattering (WAXS)
and small-angle X-ray scattering (SAXS). The in-situ study of isotactic polypropylene with
measurement of wide angle and small angle X-ray scattering (WAXS and SAXS), at varying
distances from the exit of the extruder have been successfully completed using an X-ray system
with a standard X-ray source. The processing conditions, used were: 50, 100, 200 and 400m.min-1
for the take up speed, 0.3, 0.6, and 1.2 cm3min-1hole-1 for the melt flow rates, and a spinning
temperature of 220°C. These experimental conditions produced draw down ratios ranging from 33
up to 1058. The X-ray characterization was carried in-situ at 15, 30, 45 and 60 cm from the exit of
the spinneret and also ex-situ. The results obtained show the crystallinity index and the crystalline
orientation to increase for the higher draw down rates, as expected under draw induced
crystallization conditions, and a logarithmic relationship was observed within the experimental
conditions used in this work. This communication reports the relationship between the crystallinity,
crystalline orientation and lamellar long period and draw down ratio along the spin line.
Dynamic Mechanical Behaviour of Innovative Structures Incorporating Cork
Authors: Gameiro C.P. , Cirne José
Published: March 2009

Cork is a natural cellular material which has been used for centuries, in natural and
agglomerate forms, mainly for applications related to the wine, the automotive and the construction
industries. It is a very durable and ecological material, used for thermal, acoustic and vibrating
insulation as well as packaging, among others. This paper highlights some of the aspects of a topic
of great interest, not much explored yet, which consists of the study of the dynamic mechanical
behaviour of innovative structures incorporating cork, dedicated to energy-absorption. Experimental
and numerical tests, using the finite element method software LS-DYNA™, were performed in
order to evaluate the effects of filling agglomerate cork inside thin-walled metallic tubes, with
variable geometries and thicknesses, impacted uniaxially at quasi-static and high strain rates. Some
relevant comparisons were carried out and the results obtained allowed concluding that cork might
be a viable energy-absorbing material for application in some metallic structures subjected to
impact loadings.
Determination of the Optical Constants of VO2 and Nb-Doped VO2 Thin Films
Authors: Pinto H.M. , Correia Joao , Binions Russell , Piccirillo Clara , Parkin Ivan P. , Teixeira Vasco
Published: March 2009

A numerical model was developed which enables the calculation of the optical constants
(refractive index, n and extinction coefficient, k) of thermochromic coatings based in undoped and
doped vanadium dioxide thin coatings deposited on glass for use as an intelligent window - a
window that can change the optical properties in response to the temperature. From experimental
results it can be seen that the vanadium dioxide coating prepared by Atmospheric Chemical Vapour
Deposition shows a switching efficiency of about 30% at 2500 nm. In the visible range the
transmittance and the reflectance does not change with the temperature both for the undoped and Nb
doped VO2. For the Nb doped vanadium dioxide coating the switching efficiency is about 20% at
2500 nm. From the numerical simulations a n=2.89 and k=1.33 above Tc and n=2.39 and k=0.52
below Tc (at wavelength of 2500 nm) were determined for the undoped vanadium dioxide coating.
The Nb doped vanadium dioxide coating calculations results on n= 2.45 and k=1.56 above Tc and
n=1.92 and k=0.88 below Tc.
The Use of Flory-Huggins Parameters in Characterization of Polymer-Filler Compositions
Authors: Milczewska Kasylda , Voelkel Adam
Published: March 2009

Inverse gas chromatography (IGC) has been applied to observe the interactions in filled
polymer/organic solvent as well as modified filler/polymer systems under conditions approaching
infinite dilution of the volatile component. In our study we will show that the Flory-Huggins theory
is useful in the characterization of the interaction in polymer-filler systems. Authors propose to
express the magnitude of modified filler/polymer interactions by Flory–Huggins '
23 χ parameter. We
examined the series of compositions of polyethylene (M= 35000) with different amount of modified
silica filler (5, 10, 20 % wt).
Characterization of Ni-Ti (Shape Memory Alloy) Thin Film by In Situ XRD and Complementary Ex Situ Techniques
Authors: Martins Rui M.S. , Schell Norbert , Reuther H. , Pereira Luís , Silva Rui Jorge C. , Mahesh Karimbi Koosappa , Braz Fernandes Francisco Manuel
Published: March 2009

Ni-Ti SMA are smart materials undergoing first order martensitic transformations driven
by temperature and/or stress. In the form of film they are very attractive candidates for microelectro-
mechanical system (MEMS) applications. Future directions include the production of
functionally graded films by changing deliberately the ratio Ti/Ni across their thickness. However,
for the successful development of this type of films, it is important to characterize, model and
control the variations in composition, crystalline structure and transformation temperatures. Our
approach is in-situ XRD study of the actual growth of the films of varying composition along the
thickness carried out using a deposition chamber installed at a synchrotron radiation beamline.
These studies were complemented with ex-situ analysis techniques. The results achieved on a Ni-Ti
film co-sputtered from Ni-Ti and Ti targets on a TiN buffer layer are presented in this paper. The
deposition started by using optimised parameters for a near equiatomic composition. After 1 h
(≈330 nm thick film), the Ti power was increased from 20 to 25 W, leading to the precipitation of
Ti2Ni. The evolution of the lattice parameter values of the B2 phase, calculated from the
corresponding XRD data, is clearly linked with the increase of the Ti power. The depth profile of
the atomic concentrations determined by Auger Electron Spectroscopy (AES) is in agreement with
the in situ XRD results. The temperature dependence of the electrical resistivity was used to monitor
phase transformations, Scanning Electron Microscopy (SEM) has shown the presence of twinned
martensite on the film’s surface at room temperature.
2H NMR Study of Deformed Natural Rubber Networks
Authors: Alexandre J. , Marvão M.R. , Feio G.
Published: March 2009

The orientational order generated in a cross-linked elastomer by uniaxial stress is probed
with deuterium NMR spectroscopy. Spectra of technical unfilled natural rubber (NR) vulcanisates
(cis-1,4-polyisoprene), locally swelled with o-dichlorobenzene-d4, exhibits quadrupolar doublets
under elongation, which have an explicit dependence on the extension ratio and cross-link density.
A new mechanical device was designed to fit into an NMR probe-head to permit the elongation of
the networks in the interior of the magnet without removal of the sample thus avoiding the effect of
the relaxation of the network chains after each step of uniaxial elongation and the observation of
always the same section of the stretched sample. A molecular model of rubber elasticity was applied
to describe the behavior of rubber network in mechanical and NMR experiments.
Aluminium Anodizing Waste as Coagulant for Domestic Wastewater
Authors: Correia Anabela , Franco Alexandra , Chambino Teresa , Bartolomeu Filomena
Published: March 2009

The use of Al mineral salts in wastewater treatment is a well known process and most
common [1]. For a long time we have been studying the feasibility of the aluminium anodizing
waste as coagulant. In previous works, we have tested anodizing sludges in the treatment of
municipal wastewaters and of paint industry wastewater in batch processes [2]. In this study we
have tested the use of the aluminium anodizing waste as coagulant for the treatment of municipal
wastewaters in continuous processes. Different muds from nine different anodizing facilities were
collected and prepared for use as coagulant. In addition, two mud mixtures were prepared to study
the influence of the combination of different muds in the efficiency of the treatment. The tests were
made, being controlled important parameters such as pH, turbidity and chemical oxygen demand
(COD). We have verified that the coagulation process was effective for all the muds and mixtures
tested. The formation of flocs that settle rapidly was visible and the Turbidity and COD reduction
obtained has demonstrated the efficiency of the anodizing mud as coagulant. Aluminium anodizing
plants generate a large quantity of wastes that are a burden to the industry. This works regards the
reuse of anodizing sludges in wastewater treatment.
Analysis of the Passive Layer Developed on Two Stainless Steels Co-Implanted with Chromium and Nitrogen
Authors: Abreu C.M. , Cristóbal M.J. , Merino P. , Nóvoa Xosé R. , Pena G. , Pérez M.C.
Published: March 2009

Surface analysis techniques (XPS and grazing incidence X-ray diffraction GIXRD) and
electrochemical techniques have been combined to elucidate the effect resulting from Cr+ and N+
co-implantation in the formation and evolution of passive layers generated on two different stainless
steels (AISI 430 and AISI 304L) in alkaline medium. The results show that the nitrides formed on
AISI 430, identified as (Cr,Fe)2N1-x, are less resistant to dissolution while the nitride phase formed in
AISI 304L, NCr with nanocrystalline structure, allows the compact growth of the oxide film.
Influence of Deposition Time on Properties of the RF Sputtered TiO2 Thin Films
Authors: Chaabouni F. , Costa Luís Cadillon , Selmi Mabrouk , Abaab Mohamed , Rezig Bahri
Published: March 2009

TiO2 films were prepared using radio frequency (RF) magnetron sputtering and were
deposited on glass and Si substrates. We varied deposition time at room temperature with RF
density of 3.7 W/cm2 and argon flow rate of 4 sccm. The morphological, structural, optical and
electrical properties were studied by Atomic Force Microscope (AFM), X ray Diffractometer
(XRD) and UV-VIS-NIR spectrophotometer. The transmittance is maintained in the range of 70-
90% in the visible and near-infrared range, high refractive index of 2.4 and large direct band gap of
about 3.5 eV are obtained. These films are annealed at 300°C during 2 hours. The annealing effect
is investigated in this work. The results of this study suggest that the variation of the deposition
time allow the control of the structural, optical and electrical properties of the films.
Structural and Mechanical Properties of AZOY Thin Films Deposited on Flexible Substrates
Authors: Oliveira C. , Costa Carlos M. , Rebouta L. , Viseu T. , de Lacerda-Arôso T. , Lanceros-Méndez Senentxu , Alves Eduardo
Published: March 2009

Transparent conducting Al doped ZnO films have been deposited by dc magnetron
sputtering on glass and polymer substrates at room temperature. Depositions have been carried out
from an AZOY (contains a small amount of Y2O3 in addition to Al2O3 and ZnO) target under
different conditions such as working pressure, substrate bias voltage and oxygen flow rate. The
crystallinity of the Al doped ZnO films has been improved by using low-energy-ion bombardment.
Likewise, the use of either the rotation or the static mode of the substrate during deposition
influences the crystallinity and therefore the optical parameters and the electrical resistance of the
films. Increasing the thickness of the films reduces the threshold strain at which the films can be
deformed without provoking significant changes on their electrical properties.
Nanocrystalline CNT-TiO2 Composites Produced by an Acid Catalyzed Sol-Gel Method
Authors: Silva Cláudia G. , Wang Wen Dong , Faria Joaquim L.
Published: March 2009

Carbon nanotube-TiO2 composites and pure TiO2 are prepared by a modified sol-gel
method. The nanoscaled materials obtained are extensively characterized by spectroscopic,
microscopic and calorimetric techniques. Their photoactivity is tested in the degradation of phenol
under visible illumination. A correlation between the CNT content and the changes in the UV–vis
absorption properties was found. The effect induced by CNT on the composite catalysts is explained
in terms of an interphase interaction between CNT and TiO2 in the composite catalysts.
Fire Behaviour Enhancement of Epoxy Polymer Mortars Modified with Flame Retardant Systems
Authors: Ribeiro M.C.S. , Rodrigues J.A. , Ferreira Antonio , Marques António Torres
Published: March 2009

In the present study, fire reaction improvement of an epoxy polymer mortar (PM)
formulation, induced by polymer modification with three different flame retardant (FR) systems,
was analyzed and quantified. For this purpose, several epoxy PM formulations, modified with
different contents and/or types of phosphate, metal hydroxide and brominated based FR systems,
were manufactured and tested for both, fire reaction and flexural strength. The results were
compared with those of plain epoxy PMs. Fire reaction of PM formulations was assessed by means
of the Oxygen Consumption Calorimeter test, also known as Cone Calorimeter test. This test allows
the determination of the main parameters that assess fire reaction behaviour of combustible
materials: heat release rate, smoke extinction area, carbon dioxide and monoxide release rates, and
ignitability. Test results revealed that all FR systems, in particular the phosphate based one, are
effective in improving fire reaction performance of epoxy PMs. Moreover, this improvement is
attained without significant losses of bearing carrying capacity of PM materials.
Properties of Gypsum-PCM Based Mortars for Interior Plastering of Construction Systems
Authors: Silva Nelson , Aguiar José B. , Bragança Luís M. , Freire Teresa , Cardoso Isabel
Published: March 2009

Incorporating phase change materials (PCM) in plasters is an effective solution both for
more efficient use of energy and its consumption reduction, because it allows the use of free energy
in the environment, by latent heat storage. As PCM has not binder properties, it is expected to
decrease mechanical properties of the final mortar. Also the density of the mortar decreases due to
PCM lighter specific weight. In order to be used as a final coat for wall plastering, it must verify the
requirements of the respective European Standard. This paper presents the results of the
composition development and mechanical properties (flexural, compressive and adhesive strengths)
testing and validation of three different gypsum mortars, in order to select the appropriate one for
thermal testing in test cells. The results show that the effective decrease in the studied
characteristics of the mortar does not inhibit the use for plastering, as requirements are achieved by
the three studied compositions.
Development of Automotive Plastic Pillars for Preventing Occupant Injuries by Finite Element Simulations: The Role of Material Properties
Authors: Ribeiro C.J. , Viana Julio , Vilaça F. , Azenha J.
Published: March 2009

Safety is nowadays an increasingly important issue for automotive manufacturers. Plastic
components, asides from its aesthetic function in the car interior, are required to act as passive
safety components. In this work, the impact of an anthropomorphic mass with a given mass and
velocity in a plastic pillar cover is simulated by a finite element code (ABAQUS/Explicit). The
pillar is modelled as a solid discretised by 3D solid elements. The material’s properties
(polypropylene) used in the pillar are obtained at high strain-rates and described by an elasto-plastic
model, being adopted a maximum allowable strain failure criterion. The contact between the mass,
the plastic component and the steel chassis are considered. A complete deceleration-time plot is
obtained, being calculated the values of the Head Injury Criteria (HIC(d)) and maximum
deceleration. The deformed geometry, resultant stress distribution and damaged zones are also
predicted. The properties of the material (elastic modulus, yield stress and allowable strain level) are
optimised, making extensive use of numerical simulations and a design of experiments approach, in
order to meet the envisaged standards requirements and thus mitigating occupant injuries.
Stereolitography, the Front Edge of Rapid Prototyping
Authors: Lino F. Jorge , Vasconcelos Pedro V. , Neto Rui J.L. , Paiva Ricardo
Published: March 2009

Based on the annual sales volume, stereolitography (SLA) can be considered a Rapid
Prototyping (RP) technology with a promising future. Besides being the pioneering equipment,
when RP took the first steps in 1988, this technology has been developed with interesting and fast
innovations, and a great activity in patents registration. One can assist to a strong research seeking
the enlargement of the system capacity to produce large and micro-size parts, and simultaneously
impose the technology as a mass production process that is evolving towards a true Rapid
Manufacturing (RM) technology. SLA is an excellent tool to materialize concepts and ideas due to
the high-resolution capacity, transparency and fine details of the models and prototypes that can be
produced. In this study, the state of art of SLA is analyzed and the recent innovations are presented,
and considering that the authors have a considerable experience in supervising design students,
from different universities, some of the more emblematic projects that were developed at INEGI –
Institute of Mechanical Engineering and Industrial Management, are presented. SLA and direct
conversion processes were combined to produce new products in materials such as glass, ceramics
and metals, for different industrial sectors.
Controlling the Composition of Nanosize Hexagonal WO3 for Gas Sensing
Authors: Szilágyi Imre Miklós , Saukko Sami , Mizsei János , Király Péter , Tárkányi Gábor , Tóth Attila Lajos , Szabó András , Varga-Josepovits Katalin , Madarász János , Pokol György
Published: March 2009

Hexagonal (h-) WO3 was prepared through heating hexagonal ammonium tungsten
bronze (HATB), (NH4)0.07(NH3)0.04(H2O)0.09WO2.95. By adjusting the heating temperature and
atmosphere of HATB, we could control the oxidation state of tungsten atoms and the residual
NH3/NH4
+ content in h-WO3. The as-produced h-WO3 nanoparticles with different composition
were tested as gas sensors and the effect of composition on gas sensing properties was studied. Our
results showed that oxidized h-WO3 had the best sensitivity to H2S.
Atomic Force Microscopy Studies of Alkyl-Phosphonate SAMs on Mica
Authors: Paszternák A. , Pilbáth A. , Keresztes Z. , Felhősi Ilona , Telegdi J. , Kálmán Erika
Published: March 2009

The layer formation of phosphonic acids on mica surface as a model system, from
aqueous and ethanol solutions has been investigated. The aggregation behavior (critical micelle
concentration, cmc) of molecules in the solution phase has been determined by surface tension
measurements in order to select the appropriate concentration for the layer formation experiments.
Layer formation of self-assembling molecules of alkyl-phosphonic acids has been followed by
atomic force microscopy (AFM). Nucleation, growth and coalescence of densely packed islands of
phosphonates from ethanol solution have been recorded on mica surface. The structure of islands
depends on the length of alkyl-chains. Self-assembly of phosphonates has been also observed from
aqueous solution, as presented by octyl-phosphonic acid (OcPA). The height of OcPA islands is
1.46 􀁲 0.22 nm, which is practically equal with the length of molecule (1.4 nm). This shows that
OcPA molecules form monolayer height domains on the mica surface.
Wettability of Carbon Surfaces by Molten Alkali Chloride Mixtures
Authors: Baumli P. , Kaptay György
Published: March 2009

The wettability of graphite and glassy carbon surfaces by molten alkali chlorides was
measured by the sessile drop method. Pure NaCl, KCl and CsCl, binary NaCl-CsCl and NaCl-KCl
and ternary NaCl-KCl-CsCl compositions were measured. CsCl was found to be an interfacially
active component (at the solid/liquid interface) in both binary NaCl-CsCl and ternary NaCl-KCl-
CsCl systems. From the composition dependence of the interfacial energy in the NaCl-CsCl system
the hypothesis is made on the possibility of the existence of 3[ 4 ] Cs NaCl complex.
The Influence of High-Energy Ball Milling Parameters on the Traditional W-Type Ba-Hexaferrite Properties
Authors: Kakuk Gyula , Csanády Ágnes , Sajó István E. , Papp Katalin , Németh Péter , Hargitai Hajnalka , Sztaniszláv Anna
Published: March 2009

The main task of our work was to study the influence of high energy ball milling on the process of
W-type hexaferrite material production and to compare the structural, morphological and magnetic
features of the different manufacturing ways. The products are analyzed mainly by XRD, SEM and
TEM methods. It was shown that high energy ball milling can be used to enhance the synthesis of
W-type Ba-hexaferrite due to the much smaller crystallite sizes and their larger surfaces that are
produced by the milling process and due to the activation of these surfaces.
Fabrication of U3Si2 Powder for Fuels Used in IEA-R1 Nuclear Research Reactor
Authors: Saliba-Silva Adonis M. , Durazzo Michelangelo , de Carvalho Elita F. Urano , Riella Humberto Gracher
Published: March 2009

Powdered uranium silicide (U3Si2) 20% U235 enriched is an intermetallic compound used
as nuclear fuel material dispersed in aluminum to be the meat of fuel elements. U3Si2 powder is the
state-of-the-art as nuclear fuel material mostly used in modern research reactors. Its recent
established fabrication in IPEN replaced the previous ceramic powder U3O8 used in the fuel of IEAR1
(IPEN/CNEN, São Paulo, Brazil). The U3Si2 is a compound with 92.3%wtU and 7.7%wtSi. Its
production is made by induction furnace melting using metallic uranium, produced by
magnesiothermic reaction, and pure silicon. The induction furnace melts under argon controlled
environment using zirconia crucible. Homogenization of liquid bath at 1800°C is a compromise
between crucible resistance and homogenized melting, avoiding hazardous happenings. IPEN
produced its first lot of enriched U3Si2 in September 2004, with a continuous fabrication ever since.
This research work represents the ability of having fully Brazilian supply of this strategic and high
cost nuclear material. The fuel quality meets the world quality standards required by International
Atomic Energy Agency (IAEA) and RERTR standards. Brazilian production of U3Si2 powder not
only closed the fuel cycle, from uranium mineral to fuel element, but also allowed higher
productivity of nuclear medicine radioisotopes by IEA-R1.