bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparing MIM Feedstocks for Bio-Applications Using an Agar-Based Binder
Authors: Barreiros Fatima M. , Martins A.G. , Matos Mariana , Mascarenhas João M.G. , Vieira Maria-Teresa Freire
Published: March 2009

The present study aims to prepare feedstocks for MIM (Metal Injection Molding) where
the metal powders are 316L stainless steel powders (SS). The master objective is to compare the
performance of a biodegradable binder with a commercial one based on polyolefins. Different
challenges must be overcome in SS injection molding, as follows: to decrease binder/carbon content
in feedstocks; to decrease carbon contamination during debinding and sintering; to avoid the
formation of chromium carbide and presence of precipitation-free zones; to avoid the grain growth
during sintering and to reduce the feedstock price. The optimization of the feedstocks was
performed using a torque rheometry technique. Feedstocks of coated and uncoated SS powders
mixed with an agar-based binder were used to produce sound parts. A feedstock constituted by SS
powders mixed with a high quality commercial binder was the standard. SS with agar-based on
feedstocks can admit solids content similar to those based on the commercial binder (62 vol.%). For
similar powder content, the sinters resulting from feedstocks with the agar-based binder shows a
lower quantity of solid solution of carbon and chromium carbides, absence of precipitation-free
zones than commercial feedstocks and good sinter soundness. Coating powders with nanocrystalline
stainless steel contribute to control grain growth during debinding and sintering.
Study of the Corrosion Mechanism and Corrosion Inhibition of 2024 Aluminum Alloy by SKPFM Technique
Authors: Yasakau K.A. , Zheludkevich Mikhail L. , Ferreira Mário G.S.
Published: March 2009

Aluminum alloys have found many applications in different branches of industry. In spite
of the valuable properties, there is a significant drawback because of the strong corrosion
susceptibility, especially in chloride-containing medium. The present work is focused on study of
the 2024 aluminum alloy corrosion mechanism on early stages using Scanning Kelvin Probe Force
Microscopy (SKPFM). The corrosion impact was studied measuring the Volta potential (VP) and
topography of alloy matrix and S-phase intermetallics after immersion in different electrolytes and
pH. It is shown that presence of the chloride anions in the electrolyte leads to increase of aluminum
matrix potential for about 100 mV. This can be resulted from the adsorption of chloride ions and
their incorporation into the native oxide layer changing semiconductive properties of the oxide. The
zones surrounding the S-phase intermetallics are changed more significantly demonstrating higher
increase of VP close to the inclusion. These regions are correlated with the increased oxygen
content suggesting formation of thicker oxide layer due to local polarization. Addition of an
inhibitor to electrolyte also leads to change in Volta potential that is reflected on lower corrosion
impact of aggressive environment.
Ball Milling of the β-FeSi2 Phase
Authors: Costa Benilde F.O. , Le Caër Gerard , Ramos Silva M.
Published: March 2009

A β-FeSi2 sample was ball-milled for different periods in a vibratory ball-mill and studied
by X-ray diffraction and Mössbauer spectroscopy. It transforms gradually with milling time into an
α-FeSi2 phase.
Diffusion Brazing of a γ-TiAl Alloy Using Tini 67: Microstructural Evolution of the Interface
Authors: Guedes Anibal , Viana Filomena , Pinto Ana Maria Pires , Vieira Manuel F.
Published: March 2009

A detail study focussing the microstructural evolution of the interfacial zone in the course
of the processing of Ti-47Al-2Cr-2Nb joints using Tini 67 as filler alloy was carried out in this
investigation. Experiments, aiming the understanding of the mechanisms that promote the melting
of the braze alloy, were performed below the solidus temperature of the filler, at 750 and 900°C.
Diffusion brazed samples were joined at 1000 and 1100°C, with no dwelling stage and subsequently
quenched in water in order to frozen the microstructure formed at the bonding temperature. The
interfaces were analysed by scanning electron microscopy (SEM) and by energy dispersive X-ray
spectroscopy (EDS), respectively. In the course of the heating stage, several single phase layers
were formed within the filler alloy due to the solid state interdiffusion of Ti and Ni atoms. At
900°C, the microstructure of the filler evolved form the initial Ti (α)/(Ni)/Ti/ (α) layers to a
Ti (β)/Ti2Ni/TiNi/TiNi3/TiNi/Ti2Ni/Ti (β) layered microstructure. The filler alloy begun to melt due
to the eutectic reaction between the contiguous layers composed of Ti (β) and Ti2Ni. After joining,
the main phases detected at the interfaces were α2-Ti3Al, Ti-Ni-Al and Ti-Ni intermetallics. For
joining at 1000°C, a substantial amount of residual filler (Ti2Ni and Ti (α) particles) was also
detected at the central zone of the interface. No marked evidences of residual filler zones were
noticed for joining at 1100°C; instead, a mixture α2-Ti3Al with Ti-Ni-Al or Ti2Ni intermetallics was
detected at the centre of the interface.
Mechanical Characterization of Friction Stir Welds of Two Dissimilar Aluminium Alloys of the 6xxx Series
Authors: Moreira Pedro Miguel Guimarães Pires , Santos T. , Tavares Sérgio M.O. , Richter-Trummer Valentin , Vilaça Pedro , de Castro Paulo Manuel Salgado Tavares
Published: March 2009

A study on the mechanical characterization of friction stir welds between aluminium
alloys 6061-T6 and 6082-T6 was carried out. For comparison, single alloy joints made from each
one of the two alloys were also performed. The work included microstructure examination,
microhardness tests, tensile tests and bending tests of all joint types. An approximate finite element
model of the joint, taking into account the spatial dependence of the tensile strength properties, was
made, modelling a bending test of the weldments.
Phase Transitions in the Cu-Sb-S System
Authors: Braga M. Helena , Ferreira Jorge A. , Lopes C. , Malheiros Luis Filipe
Published: March 2009

The aim of this study is to determine the thermodynamic influence of the presence of
Cu3SbS3, Cu2S and Sb2S3 in the formation of Cu12Sb4S13 - equivalent to mineral tetrahedrite. Thus,
the Cu-Sb-S system is studied. Twenty three samples, with compositions that essentially lay along
the vertical section Cu2S-Sb2S3, were prepared. The samples were analyzed by Electron Microprobe
(EPMA) in order to determine the room temperature phases' composition. Samples were also
analyzed by Differential Thermal Analysis (DTA/DSC) in order to establish thermal transitions, and
by X-Ray Diffraction (XRD), at room and high temperatures, so as to determine the phases that are
present in the equilibria at certain temperatures. The experimental phase diagram was established
and the results were compared with those available in the literature.
Immobilisation of Ferricinium Cation into ETS-10 by Ion Exchange under Microwave Irradiation
Authors: Coelho Ana C. , Brandão P. , dos Santos António M. , Rocha João , Gonçalves Isabel S.
Published: March 2009

The microporous titanosilicate ETS-10 was subjected to three cycles of ferricinium ion
([(η5-C5H5)2Fe]+, Fc+) exchange by using aqueous solutions of ferricinium hexafluorophosphate and
microwave-assisted heating. The resultant hybrid inorganic-organometallic (ETS-10/Fc+) materials
were characterised by elemental analysis, ICP-AES, FTIR and Raman spectroscopy, powder X-ray
diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance (DR) UV-Vis, 29Si and
23Na solid-state NMR. The results support the successful inclusion of Fc+ in the pores of the
inorganic host by ion exchange of extra-framework sodium and potassium ions.
Functionalisation and Characterization of SBA-15 Nanostructured Silica Modified with 2-Benzothiazolethiol
Authors: Cesarino Ivana , Cavalheiro Éder T.G. , Marino Glimaldo , Matos Jivaldo R.
Published: March 2009

Mesoporous silica can be modified and functionalised by immobilisation of organic
substances covalently bonded to the silanol groups on the silica surface. This paper describes the
modification of a SBA-15 nanostructured silica with 2-benzothiazolethiol. After derivatization the
modified silica was chacacterized by elemental analysis, IR spectroscopy, thermal analysis (TG and
DSC), NMR in solid phase and scanning electron microscopy.
Effect of Annealing Conditions on the Grain Size of Nanocrystalline Copper Thin Films
Authors: Simões Sonia , Calinas Rosa , Ferreira P.J. , Vieira Maria-Teresa Freire , Viana Filomena , Vieira Manuel F.
Published: March 2009

Nanocrystalline metals demonstrate a broad range of fascinating mechanical properties at
the nanoscale, namely a significant increase in hardness and superior yield stress. In this regard,
understanding grain growth in nanocrystalline metals is crucial, particularly because nano size
grains are characterized by a high curvature, which results in a high driving force for grain growth.
In this work, the effect of annealing conditions on grain size of copper nanocrystalline thin films
was investigated. The nanocrystalline copper thin films were first deposited by d.c. magnetron
sputtering on a copper substrate. The specimens were then annealed in vacuum at 100, 300 and
500°C from 10 minutes to 5 hours. Transmission electron microscopy observations revealed that the
as-deposited thin films have a bimodal grain size distribution; an average grain size of 43±2nm and
the presence of nanotwins. Abnormal grain growth was observed for some samples annealed.
Increasing the annealing time induced significant grain growth and promoted twin formation in the
larger grains. Finally, the hardness of these nanocrystalline Cu thin films was determined using
atomic force microscope. The relation between mechanical properties, annealing conditions and
grain size was analyzed.
Bonding γ-TiAl Alloys Using Ti/Al Nanolayers Doped with Ag
Authors: Duarte Liliana I. , Viana Filomena , Vieira Manuel F. , Ramos Ana Sofia , Vieira Maria-Teresa Freire , Klotz U.E.
Published: March 2009

Successful solid state bonding of titanium aluminides requires the use of high
temperature and pressure. In previous works, authors have demonstrated that the use of Ti/Al
multilayer thin film as an interlayer, deposited by d.c. magnetron sputtering onto the joining
surfaces, can effectively lower the bonding temperature. The enhanced diffusivity of these
nanometric layers and the heat evolved by the formation of γ-TiAl improves the joinability of
titanium aluminide by solid-state diffusion bonding. In the present work, further improvement of the
process was pursued by doping the interlayer with 2.8 at.% of Ag; previous studies have confirmed
that silver favours the transformation Ti+Al→γ-TiAl. The solid-state diffusion bonding experiments
were performed in vacuum by applying 50 MPa at 900°C for 1 h. The effect of the third element on
the microstructure and chemical composition along the bonding interface has been analyzed.
Microstructural characterisation of the interface was performed by scanning and transmission
electron microscopy. Chemical compositions were analysed by energy dispersive X-ray
spectroscopy. No defects were observed at the interface and sound bonding was achieved between
the interlayers and base γ-TiAl. The bonding interface shows a fine-grained microstructure, slightly
coarser than the one formed at the same temperature with the undoped Ti/Al multilayer.
Preparation and Properties of Novel In Situ Composite Materials Based on Polyethylene-Polyamide Oriented Blends
Authors: Dencheva Nadya , Oliveira Maria Jovita , Carneiro Olga S. , Nunes Teresa G. , Denchev Zlatan Z.
Published: March 2009

The objective of this study is to manufacture and investigate novel nanostructured polymer
composites (NPC) based on oriented blends of high-density polyethylene (HDPE) and polyamide 6
(PA6). Conventional polymer processing techniques are used for this purpose including extrusion
blending, cold drawing and compression molding. Thus, various polymer blends are prepared
comprising 10 and 20 wt% of PA6 and 0-10 wt% of a copolymeric compatibilizer. These blends are
cold-drawn to high draw ratios and the oriented strands so produced are further compression molded
at various temperatures between the melting points of HDPE and PA6. All NPC obtained are
characterized by microscopy techniques, solid state NMR, mechanical tests and wide- and
small-angle X-ray scattering from synchrotron. The mechanical and structural data of NPCs are
discussed with relation with the polyamide fibrils’ orientation, as well as with the effect of
compatibilizer at the matrix-fibrils interface.
Preparation of Biodegradable Materials by Reactive Extrusion
Authors: Moura Isabel , Machado Ana Vera , Duarte Fernando M. , Botelho Gabriela , Nogueira Regina
Published: March 2009

This work aimed to prepare biodegradable polymeric materials based on blends of a
synthetic high density polyethylene (HDPE) and biodegradable polymers such as polylactic acid
(PCL) and poly(caprolactone) (PLA), in a co-rotating twin-screw extruder. A polyethylene
modified with maleic anhydride was used as compatibiliser. The mechanical results showed that the
addition of PLA improves the blends stiffness while the addition of PCL leads to materials with a
greater elongation at break and a lower Young modulus. This feature is related with the mechanical
properties of each material as well as the adhesion between them. Concerning the biodegradability
tests, it was found that HDPE/PCL blend presents the highest degree of biodegradability.
Catalytic Performance of Copper-Substituted Polyoxotungstate Materials and X-Ray Structure of a New Sandwich-Type Compound
Authors: Balula Salete S. , Cunha-Silva Luís , Santos Isabel C.M.S. , Paz Filipe A. Almeida , Rocha João , Nogueira Helena I.S. , Cavaleiro Ana M.V.
Published: March 2009

Mono-substituted and sandwich-type copper substituted polyoxoanions ([PW11CuO39]5−
and [Cu4(H2O)2(PW9O34)2]10−) were studied as catalysts for the epoxidation of cyclooctene and
geraniol, using the green oxidant H2O2, with the results suggesting good efficiency at room
temperature. High selectivity and reasonable conversion data were found after the first minutes of
reaction. The copper centre may be responsible for this performance and our on-going research
focuses in the preparation of new materials incorporating copper into polyoxometalates (POMs). In
this context, we have also isolated a new crystalline dimeric sandwich-type polyoxocoppertungstate
{H7.05[Cu3WO(H2O)(CuW9O34)(Cu0.6W9O34)]}7.75−. This compound was isolated as potassium salt
and structurally characterized by FTIR and single-crystal X-ray diffraction (XRD). The
polyoxoanion is composed by the [CuW9O34]12− and [Cu0.6W9O34]12.8− anionic fragments, joined
together by a rhomb-like arrangement of three Cu2+ and one W6+
metallic centres, all exhibiting
octahedral coordination geometries.
The Thermomechanical Processing Conditions and the Mechanical Properties of Injection Molded PP/PC Blends
Authors: Krol Mariusz , Bilewicz Marcin , Viana Julio , Dobrzański Leszek Adam
Published: March 2009

This investigation aims at establishing the relationships between the thermomechanical
conditions and the mechanical properties of a direct injection moulded polypropylene/polycarbonate
blend (70/30wt composition). Rectangular plates (2 mm thick) were injection moulded by
systematic variations of the processing conditions. The moulding programme was based on a design
of experiments (DOE) approach, being considered variations in two levels of the melt (240 and
280°C) and the mould (5 and 80°C) temperatures and the injection flow rate (3.8 and 38 cm3/s). For
comparison purposes, neat polypropylene was also moulded under the same set of processing
conditions. In both cases the thermomechanical environment was characterised by computer
simulations of the mould filling phase using commercially available codes (Moldflow). Tensile
specimens were cut from the injected plates. The microstructure of the mouldings was characterized
by polarized light microscopy, PLM. The mechanical characterization encompass the assessment of
the tensile (at 5 mm/min at 23 °C) and impact toughness (unnotched Charpy test). The results are
analysed by ANOVA. The presence of PC particles affects the crystallization of PP, this being
revealed on the mouldings microstructures observed by PLM that are distinct for the neat and
PP/PC blends. The mechanical properties are determined differently by the processing variables.
The Effect of Thermo-Mechanical Environment on the Shrinkage and Warpage in Thermoplastic Parts
Authors: Alves P.S. , Pontes A.J.
Published: March 2009

During the injection moulding process, the material is subjected to successive
transformations, being submitted to a thermo-mechanical environment that determines the final
dimensions of the part. This environment is characterized by several parameters which are related to
material properties, the mould design, equipment and process variables. As a result, deviations of
the dimensions of the moulded parts from the dimensions of the cavity cannot be avoided. If
differences on shrinkage occur, caused for example by anisotropies of the material or non-uniform
cooling, distortions will happen. In order to predict this two effects on the injection cycles is require
one strategy to monitoring and control the process variables. The aim is to achieve highest quality
control of all manufacture parts. This paper presents the effect of different holding pressures and
mould temperatures on shrinkage and warpage in two different materials, one amorphous (PC) and
another semi crystalline (PP). An instrumented mould was manufactured. During the injection
moulding process sensors signals were continuously monitored by a Data Acquisition System. The
experimental results were compared with predictions made by commercial software.
Cure and Rheological Analysis of Reinforced Resins for Stereolithography
Authors: Gaspar J. , Bártolo P.J. , Duarte Fernando M.
Published: March 2009

The rising of consumers’ demands and an ever increasing pressure of international
markets imposed a deep change in the product development process to respond to an increasing
product complexity and higher quality, as well to the need to promptly introduce products into the
market. Stereolithography plays an important role on this new product development context. This
technology produces models for thermosetting resins through a polymerisation process that
transforms liquid resins into solid materials. In this work, a new route to produce metallic parts
through stereolithography is explored. The curing analysis of hybrid reinforced polymeric systems,
polymerised through radicalar or/and cationic mechanisms, is investigated. The rheological
behaviour of these polymeric systems is also evaluated due to its importance for recoating. The
influence of other processing and material characteristics like light intensity, initiator concentration,
low powder size of metallic powders, degree of dilution, etc. is also investigated.
The Comparison of the Thermal Behaviour of Leisure and Sports Clothing Using Conventional and New Textile Materials
Authors: Geraldes Maria José , Hes Lubos , de Araújo Mário , Belino Nuno , Nunes Mário
Published: March 2009

This work reports on research being carried out in the area of functional knitted fabrics
with a special structure incorporating hydrophobic fibres near to the skin and suction channels of
hydrophilic fibres to suck moisture from the skin on the hydrophilic layer away from the skin; in
this way, comfort is maximised in active wear as the fabric does not feel wet near to the skin.
Mode II Fracture Characterization of Pinus Pinaster Wood
Authors: de Moura Marcelo F.S.F. , Silva M.A.L. , Morais J.J.L. , de Morais A.B. , Oliveira J.M.Q.
Published: March 2009

This paper describes experimental and numerical studies on the application of the End
Notched Flexure (ENF) and End Loaded Split (ELS) tests to mode II wood fracture characterization.
In this context, ENF and ELS specimens were used to determine GIIc of a clear Pinus pinaster wood
in the RL system, which is the most relevant for structural design. In mode II fracture tests the crack
faces are in contact, thus hindering a rigorous visualization of the crack tip. This makes classic
methodologies based on crack length measurement during experimental tests inadequate, since they
induce significant errors on the mode II fracture properties. To overcome this experimental problem
a Compliance Based Beam Method (CBBM) is used. This new data reduction scheme does not
require crack length monitoring and includes the effect of the Fracture Process Zone (FPZ) ahead of
crack tip. Furthermore, the clamped cross-section rotation of the ELS specimen is also taken into
account. In the present work a numerical analysis considering a cohesive damage model was
performed with a cohesive damage model in order to validate the application of the CBBM to the
experimental results. The results confirmed the adequacy of the CBBM and the applicability of the
ENF and ELS tests for mode II wood fracture characterization.
Cellulose-Based Anisotropic Composites
Authors: Borges João Paulo , Godinho M.H.
Published: March 2009

In an attempt to improve the mechanical properties of an all-cellulose based composite
we made solid flexible films containing microcrystalline cellulose fibres produced by a shearing
casting technique. To an anisotropic (liquid crystalline) solution of 2-hydroxypropylcellulose (HPC)
in N,N – dimethylacetamide (60 w/w %) were added AVICEL fibres (0, 2, 4, 6, 10, 12 w/wHPC
%). After homogenization these solutions were poured into a Teflon plate and sheared at a constant
rate of 5 mm/s. The cellulosic microfibres in the liquid crystalline polymer medium were partially
aligned by shear flow. Mechanical and morphological properties of the films were investigated
using tensile tests, polarized optical microscopy and scanning electron microscopy. The mechanical
properties of these films, as expected, are higher than those of the films produced from an isotropic
solution of HPC. The results show that the orientation of the microfibres, and the mesoscopic
properties, can be tuned by adjusting the topography of the nematic matrix in the micro-nano scale.
Theoretical Study on the Influence of Iron Mordant in the Optical Properties of Natural Dyes
Authors: Carreira M. , Candeias António Estevao , Manhita A. , Costa C.T. , Mendes P.J. , Palace Carvalho A.J. , Prates Ramalho J.P.
Published: March 2009

Geometry optimization of free alizarin, purpurin and luteolin and coordinated Fe(II)
complexes was performed at DFT/B3LYP level. TD-DFT spectra were also calculated for free and
coordinated alizarin and luteolin. For the Fe(II) complexes several spin multiplicities have been
calculated and quintuplet spin structures were found to be the most stable. In the luteolin-Fe(II)
complex, the coordination of the chromophore with the iron leads to a decrease in the lower energy
band. In the case of luteolin complex, a new band emerges due to interactions between the
delocalized π electrons of the luteolin molecule with the d metal orbitals.
Electrical Properties Studies of a Cork/TetraPak®/Paraffin Wax Composite
Authors: Carmo Lança M. , Peuckert Stefan , Neagu Eugen R. , Gil Luís , Silva Paulo C. , Marat-Mendes José N.
Published: March 2009

Lately the electrical and dielectric properties of cork and some cork-based materials
(commercial and non-commercial) have been studied in order to understand their ability to store
electrical charge. The main problem found so far is related to the water content in cork, only of a
few % weight, but large enough to influence greatly the conductivity of cork and, consequently, the
charge storage capability. To overcome this problem cork has been combined with hydrophobic
materials. In this work a commercial wax (paraffin wax) was used to produce a cork/paraffin
composite by hot pressing. After milled and mixed natural cork, TetraPak® containers waste and
paraffin were pressed to make plaques of a new composite. Different concentrations of cork,
TetraPak® and paraffin, different granules size, different temperature and pressure were used to
produce the samples. The electrical properties of the new composite were measured by the
isothermal charging and discharging current method and the results compared to previously ones
obtained for natural cork and other derivative products. The new composite has shown to have
lower conductivity than the commercial agglomerate, which makes it a better material for charge
storage.
Hybrid Bioactive Glass-Polyvinyl Alcohol Prepared by Sol-Gel
Authors: Costa Hermes S. , Mansur Alexandra A.P. , Barbosa-Stancioli Edel Figueiredo , Pereira Marivalda , Mansur Herman S.
Published: March 2009

Bioactive glasses are materials that have been used for the repair and reconstruction of
diseased bone tissues, as they exhibit direct bonding with human bone tissues. However, bioactive
glasses have low mechanical properties compared to cortical and cancellous bone. On the other
hand, composite materials of biodegradable polymers with inorganic bioactive glasses are of
particular interest to engineered scaffolds because they often show an excellent balance between
strength and toughness and usually improved characteristics compared to their individual
components. Composite bioactive glass-polyvinyl alcohol foams for use as scaffolds in tissue
engineering were previously developed using the sol-gel route. The goal of this work was the
synthesis of composite foams modified with higher amounts of PVA. Samples were characterized
by morphological and chemical analysis. The mechanical behavior of the obtained materials was
also investigated. The degree of hydrolysis of PVA, concentration of PVA solution and different
PVA-bioactive glass composition ratios affect the synthesis procedure. Foams with up to 80 wt%
polymer content were obtained. The hybrid scaffolds obtained exhibited macroporous structure with
pore size varying from 50 to 600 µm and improved mechanical properties.
Compositional Analysis of Polychromes by Laser-Induced Breakdown Spectroscopy
Authors: López Ana J. , Mateo Mari Paz , Santaclara Ana , Yáñez Armando
Published: March 2009

This study deals with the analysis and characterization of wood polychromes by means of
Laser-Induced Breakdown Spectroscopy (LIBS). Specimens from a Baroque altarpiece have been
analyzed by using a Q-switched Nd:YAG laser source at the wavelength of 355 nm. Previously, a
library of characteristic LIBS spectra of the most commonly used pigments and other materials
involved was obtained. The knowledge of these spectra allowed us to identify the main constituents
of the different layers in polychromes and to obtain compositional depth profiles.
Behaviour of Membrane Construction Materials under Bi-Axial Tensile Loading
Authors: Chen S.H. , Ding Xin , Sousa Fangueiro Raul Manuel Esteves , Yi H.L. , Ni J.
Published: March 2009

The aim of this research is to find a feasible method for the estimation of the tensile
behaviour of woven membrane construction materials under bi-axial loading. During the model
development, the woven membrane materials are treated as orthotropic, elastic and linear. Based on
the constitutive relationships for orthotropic and elastic materials, two equations sets are deduced
for the estimation of modulus in the warp and the fill direction respectively when suffering from the
bi-axial loading. To checkout the validity of the estimation, seven groups of biaxial tensile tests
with stress ratios of 1:0, 1:1, 2:1, 5:1, 1:2, 1:5 and 0:1 have been carried out on two kinds of PVCcoated
woven membrane materials. From the comparison of the experiments and the prediction, it
can be noticed that the model can achieve ideal results when it comes to the estimation of modulus
in the leading direction, which is the direction with a higher stress than the other one. Therefore,
based on the hypothesis of orthotropic, elastic and linear materials, there is an easy way to estimate
the bi-axial tensile properties of woven membrane materials in the leading direction only through
the uni-axial tensile tests.
Drilling of Fibre Reinforced Plastic Laminates
Authors: Durão Luís Miguel P. , Magalhães A.G. , Marques António Torres , Baptista A.M. , Figueiredo M.
Published: March 2009

The use of fibre reinforced plastics – FRP’s – in structures is under a considerable
increase. Advantages of their use are related with their low weight, high strength and stiffness. The
improvement of the dynamic characteristics has been profitable for aeronautics, automobile, railway,
naval and sporting goods industries. Drilling is a widely used machining technique as it is needed to
assemble parts in a structure. This is a unique machining process, characterized by the existence of
two different mechanisms: extrusion by the drill chisel edge and cutting by the rotating cutting lips.
Drilling raises particular problems that can reduce mechanical and fatigue strength of the parts. In
this work, quasi-isotropic hybrid laminates with 25% of carbon fibre reinforced plies and 4 mm
thickness are produced, tested and drilled. Three different drill geometries are compared. Results
considered are the interlaminar fracture toughness in Mode I – GIc –, thrust force during drilling and
delamination extent after drilling. A bearing test is performed to evaluate tool influence on the load
carrying capacity of the plate. Results consider the influence of drill geometry on delamination. A
correlation linking plate damage to bearing test results is presented.
Numeric Study of PMMA Flow on a Small Dimension Channel: A First Approach
Authors: Clemente C.M. , Martins N. , Simões J.A.
Published: March 2009

Polymethylmethacrylate has been used in orthopaedic surgery for the fixation of
prosthetic implants for forty years. Cement characteristics, namely rheological and flow properties,
greatly affect implant success. Moreover, knowing predictable and reproducible cement flow
characteristics allows the surgeon to establish more rigorous handling conditions and prosthesis
precise positioning. In contrast to the relatively large amount of work on mechanical properties of
bone cements, few data have been published oh their rheological properties. Computational fluid
dynamics (CFD) codes using VOF (volume-of-fluid) method has proven to be a useful and robust
tool method to simulate multi-material flows with immiscible interfaces. This work explores and
describes the possibility of to use a commercial available CFD package (ANSYS CFX®) in the
study of PMMA flow on a small dimension multy-channel system.
Failure Analysis of Metallic Materials in Sheet Metal Forming Using Finite Element Method
Authors: Teixeira Pedro , dos Santos Abel , de Sá J. César , Barata da Rocha Augusto
Published: March 2009

The optimisation of sheet metal processes by using numerical simulations has become a
key factor to a continuously increasing requirement for time and cost efficiency, for quality
improvement and materials saving, in many manufacturing areas such as automotive, aerospace,
building, packaging and electronic industries. The introduction of new materials brought new
challenges to sheet metal forming processes. The behaviour observed with conventional steels may
not be applied when using high-strength steels or aluminium alloys. Numerical codes need to model
correctly the material and different constitutive equations must be considered to describe with
greater accuracy its behaviour. This enhancement of material description may provide a better
prediction of the forming limits, enabling an assessment of the influence of each forming parameter
on the necking occurrence and the improvement of press performance. This paper presents two
numerical approaches for failure prediction in sheet metal forming operations: one is the
implementation of the Lemaitre’s ductile damage model in the Abaqus/Explicit code in accordance
with the theory of Continuum Damage Mechanics and the other is the traditional use of FLDs,
usually employed as an analysis of the finite element solution in which the necking phenomenon is
carried out in the framework of Marciniak-Kuczinsky (M-K) analysis coupled with the conventional
theory of plasticity. The previous strategies and corresponding results are compared with two
experimental failure cases, in order to test and validate each of these strategies.
Second-Generation Aluminium Extraction Residue Used as Devitrification Aid for Glass-Ceramics
Authors: Ferreira M.C. , Acchar Wilson , Segadães Ana M. , de Mello-Castanho Sonia Regina Homem
Published: March 2009

Brazil has one of the world’s most important Bauxite deposits, the raw material for the
aluminium extraction metallurgy. This work is focused on finding a suitable application for the
white dross residue (WDR), a second-generation waste material produced during the metal recovery
from the slag left after the primary extraction of aluminium from the ore. A commercial lime-silica
based glass frit was used, to which WDR additions were made (up to 30 wt.%), aimed at studying
the devitrification process of the glasses produced. Such mixtures were melted at temperatures
varying from 1100 to 1500°C and the resulting fritted glasses were heat treated at 900°C. The
starting materials and the mixtures thereof were characterized before and after thermal treatment by
differential thermal analysis, X-ray diffraction and fluorescence, and scanning electron microscopy.
The results obtained showed that the WDR is easily incorporated into the glass matrix and causes
easy devitrification after short heat treatment periods at low temperature.
Characterisation of the Filter Elements of End-of-Life Biological and Chemical Protection Masks Used by the Army
Authors: Cabral Marta , Bordado João C. , Diogo António Correia , Margarido Fernanda
Published: March 2009

The main purpose of the present study is to assess the usefulness of filter cartridges from
end-of-life biological and chemical protection masks, for other applications (with increased added
value) instead of landfill deposition. Filters with different ages up to fifty years, were dismantled
and divided in their components. Physico-chemical characterisation of each filter cartridge
component was performed using different techniques such as: optical microscopy, Fourier transform
infrared spectroscopy, pyrolysis, particle size distribution by laser diffraction, surface area
determination from the nitrogen adsorption isotherms at 77K, determination of open porosity by
helium pycnometry, and dynamic mechanical thermal analysis in the temperature range from -100°C
to 200°C. It is shown that the loss of resilience of the rubber sealant is the main factor that controls
the shelf life of filter cartridges. On the other hand, most of the charcoal in the activated carbon
cloth remains active and can be useful for other less severe applications such as the removal of
dissolved components from freshwater and/or marine systems.
Preparation of Photocatalytic Nanostructured TiO2 Thin Films
Authors: Di Paola A. , Addamo M. , Bellardita M. , García-López E. , Marcì G. , Palmisano L.
Published: March 2009

Photoactive films consisting of pure anatase, brookite or rutile were deposited on glass
slides by a dip coating process from water dispersions or solutions obtained by using TiCl4 as the
precursor. The films were characterized by X-ray diffraction, scanning electron microscopy and
atomic force microscopy. The photocatalytic activity of the various samples was evaluated by using
the photooxidation of 2-propanol in gas solid regime as probe reaction. Brookite and anatase films
showed a good photoactivity degrading the substrate and the propanone produced during the
reaction.
Selective Catalytic Reduction of NOx over Zeolite-Coated Cordierite-Based Ceramic Foams: Water Deactivation
Authors: Dias Susana , Oliveira Fernando A. Costa , Henriques C. , Ribeiro F.R. , Rangel Carmen M. , Ribeiro M. Filipa
Published: March 2009

The reactors used for Selective Catalytic Reduction (SCR) of NOx require low pressure
drop structured catalyst packing. Structured packings, such as ceramic foams, are gaining increasing
interest for application in low pressure drop reactors, membrane reactors and catalytic distillation
units. In this work, cobalt ion exchanged mordenite (Co-HMOR)-coated cordierite-based foams
produced by the replication method were evaluated for catalytic reduction of NOx with methane.
The addition of 0.3 wt.% Pd to 2 wt.% Co-HMOR leads to a material that can convert 50 % NOx to
N2 at 450 °C in a reaction mixture containing 2000 ppm CH4, 1000 ppm NOx, 5 % O2 and balance
helium, at GHSV=17000 h-1. Although in an early stage of development, an efficient coating
procedure was explored and different ways of exchange of Co and Pd cations into mordenite
(Si/Al=10) were studied. Additions of 2 wt.% fumed silica enhanced adhesion of the zeolite onto
the ceramic foam. Pd-exchanged Co-HMOR showed to be very sensitive to steam. A 50 % decrease
in NOx conversion to N2 was observed after Pd/Co-HMOR samples were exposed at 450 °C to a
reaction mixture containing 2 vol% H2O. Although further research is needed to ascertain the
mechanism of this deactivation behaviour, agglomeration of Pd forming PdO particles is envisaged.
The Interfacial Diffusion Zone in Magnetron Sputtered Ni-Ti Thin Films Deposited on Different Si Substrates Studied by HR-TEM
Authors: Martins Rui M.S. , Beckers Manfred , Mücklich A. , Schell Norbert , Silva Rui Jorge C. , Mahesh Karimbi Koosappa , Braz Fernandes Francisco Manuel
Published: March 2009

Ni-Ti Shape Memory Alloy thin films are suitable materials for microelectromechanical
devices. During the deposition of Ni-Ti thin films on Si substrates, there exist interfacial diffusion
and chemical interactions at the interface due to the high temperature processing necessary to
crystallize the film. For the present study, Ni-Ti thin films were prepared by magnetron cosputtering
from Ni-Ti and Ti targets in a specially designed chamber mounted on the 6-circle
goniometer of the ROssendorf BeamLine (ROBL-CRG) at ESRF, Grenoble (France). The objective
of this study has been to investigate the interfacial structure resulting from depositions (at a
temperature of ≈ 470°C) on different substrates: naturally oxidized Si(100), Si(111) and poly-Si
substrates. A detailed High-Resolution TEM analysis of the interfacial structure has been
performed. When Ni-Ti is deposited on Si(100) substrate, a considerable diffusion of Ni into the
substrate takes place, resulting in the growth of semi-octaeder A-NiSi2 silicide. In the case of Ni-Ti
deposited on Si(111), there appears an uniform thickness plate, due to the alignment between
substrate orientation and the [111]-growth front. For Ni-Ti deposited on poly-Si, the diffusion is
inhomogeneous. Preferential diffusion is found along the columnar grains of poly-Si, which are
favourably aligned for Ni diffusion. These results show that for the Ni-Ti/Si system, the morphology
of the diffusion interface is strongly dependent on the type of substrates.
Electrochemical and Surface Analytical Studies of Silver Deposits for Industrial Electroplating
Authors: Anastassakis Giorgios , Sequeira César A.C.
Published: March 2009

For silver plating, mainly silver cyanide solutions are used and this is extensively treated
in the literature. Yet, in view of the growing concern for environmental problems, they will have to
be replaced because of their toxic properties. In the present work, the appropriateness of thiosulphate
) O S ( 2
3 2
− , a complexing agent for silver of common use in photographic applications, as
an alternative for cyanide in electroplating baths is investigated. The kinetic characteristics of the
reduction are determined, since they fix at which rate the plating can proceed. Prior to the kinetic
study, requiring measurements in solutions of varying composition, the thermodynamic data on
complex formation between Ag+ and − 2
3 2O S ions are analysed. And finally, the composition and
the morphology of the silver deposits are examined as a function of the plating conditions.
Electrochemical and analytical physical techniques are used.
The Influence of the Substrate on the Mechanical Properties of Si-Doped DLC Thin Films
Authors: Moura e Silva Carlos W. , Branco Jose R.T. , Oliveira Marta C. , Antunes Jorge M. , Cavaleiro Albano
Published: March 2009

In this work, Si-doped DLC films were deposited on stainless steel (316SS) and
polycarbonate (PC) substrates by RF-PACVD in gas mixtures of SiH4+CH4, with 2, 5 and 10 vol.%
SiH4. The increase of the Si content in the films led to a progressive drop in the hardness from 30
GPa down to 23 GPa whereas the elastic modulus increased from 124 GPa up to 146 GPa, as
measured in the SS coated substrates. In the case of coated PC samples pop-in was observed in the
loading curve which was interpreted by finite element simulation and nanoscratching techniques.
Fibrous Reinforcing System to Increase the Shear Resistance of High Strength Concrete
Authors: Santos Simão , Barros Joaquim , Lourenço Lúcio
Published: March 2009

The available research has evidenced that discrete steel fibers can increase significantly
the shear resistance of High Strength Concrete (HSC) structural elements when High Strength Fiber
Reinforced Concrete (HSFRC) is designed in such way that fiber reinforcing mechanisms are
optimized. In general, the increase of the concrete compressive strength is associated to an increase
of its compactness, resulting benefits in terms of durability, but a strong concern emerges related to
the integrity of this material, since it fails in a too brittle mode when submitted to high temperatures.
To contribute for the knowledge about the benefits provided by discrete steel fibers when added to
HSC applied to laminar structures, an experimental program composed of slab strips submitted to
shear loading configuration was carried out. Uniaxial compression tests with cylinders of 150 mm
diameter and 300 mm height, and bending tests with 600×150×150 mm3 beams were executed to
assess the compression and bending behavior of the developed HSFRC. To evaluate the influence of
the percentage of fibers in the shear resistance of laminar structures, three point loading tests with
slab strips of 800×170×150 mm3 dimensions were performed. Taking the obtained experimental
results, the applicability of the formulation proposed by RILEM TC 162-TDF was evaluated. Test
results showed that, even with relative low dosages of steel fibers, the increment in shear resistance
was significantly increased. The main obtained results in the research program are presented and
discussed in this paper.
Crack Growth Orientation in Two Structural Materials under Multiaxial Fatigue Loading
Authors: Reis Luís G. , Li Bin , de Freitas Manuel
Published: March 2009

In real engineering components and structures, many accidental failures are due to
unexpected or additional loadings, such as additional bending or torsion, etc. Therefore, it has
attracted more research attentions to study the mechanical behavior of materials under complex
loading conditions. Two typical structural materials are studied and compared in this paper: AISI
303 stainless steel and 6060-T5 Aluminum alloy. The objective is to study the effects of multiaxial
loading paths on the crack initiation and orientation of the two materials studied. Fatigue tests were
conducted in a biaxial testing machine. Fractographic analyses of the fracture surface were carried
out by optical microscope and SEM approaches. In addition to the experimental studies, theoretical
predictions of the damage plane were made using critical plane approaches. Comparisons of the
predicted orientation of the damage plane with the experimental observations are shown. The
applicability of the multiaxial fatigue criteria for the two materials is discussed. It was shown that
the two materials studied have different crack orientations under the same loading path. This
observation appears to show that the applicability of the fatigue models is dependent on the material
type and multiaxial microstructure characteristics.
Polarisation Behaviour of Calcium Phosphate Based Ceramics
Authors: Gittings J.P. , Bowen Chris R. , Turner I.G. , Baxter F.R. , Chaudhuri J.B.
Published: March 2009

This paper studies the effects of porosity, sintering atmosphere and composition on the
polarisation behaviour of calcium phosphate (CaP) ceramics. Hydroxyapatite (HA) and α-
tricalcium phosphate (α-TCP) materials were prepared as both dense discs and as porous samples
with interconnecting porosity. Materials were sintered in either air or water vapour at 1300°C and
poled at a variety of temperatures, applied electric fields and time periods to optimise the
polarisation properties of the materials. Thermally Stimulated Depolarisation Current (TSDC)
measurements were used to investigate the degree of polarisation of the HA and α-TCP ceramics.
A high depolarisation current was observed for both the porous HA and α-TCP ceramics. Sintering
in water vapour also increased the depolarisation current due to reduced dehydration reactions,
which result in a greater concentration of hydroxyl ions.
Failure Mechanisms on Exhaust Systems of Naval Gas Turbines
Authors: Martins Rui F. , Branco Carlos M. , Gonçalves-Coelho António M. , Gomes Edgar C.
Published: March 2009

Some exhaust systems of naval gas turbines have been periodically repaired due to
thermal-fatigue crack propagation after entering into service. Those structures were made of
austenitic stainless steel grade AISI 316L in thin wall plates, which were bent in rolling machines
and welded with longitudinal and circumferential joints by means of shielded metal arc, TIG or
MIG/MAG welding processes. The plate thickness is about 3.7 mm and the temperature on the
exhaust system is approximately 500°C and 350°C in the critical zones, which are located in the
lower and intermediate regions of the exhaust system.Several cracks were detected at the critical
regions, near the weld toe of butt and T-welded joints. The stress concentration factors induced by
the weld angle, toe radius and rolled surface finishing diminishes the fatigue life strength. Some
cracked material samples were taken out from the exhaust system structure and were analysed with
a Scanning Electron Microscope (SEM/EDS), in order to determine the failure mechanisms
involved in the crack propagation process. Those results are presented in the paper. Several high
temperature fatigue and creep tests were performed with CT specimens. The mechanisms of crack
propagation on the CT specimens were studied by SEM and compared with the fracture surfaces
obtained from the samples taken out from the structure. The carbide precipitation on the grain
boundaries was also studied.