bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Work on Possibilities to Predict Casting Defects in LPDC Brass Castings
Authors: Muikku Arto , Hartikainen Jari , Vapalahti Sami , Tiainen Tuomo
Published: March 2009

In water tap production 0.5 mm of material needs to be ground off from the surface of
LPDC (Low Pressure Die Casting) brass castings in order to remove the defects deteriorating the quality of later applied coating. In order to minimize the amount of removed material the causes of these defects need to be discovered and properly connected with the process parameter window. At Oras Oy foundry in Finland, nearly 100 castings were produced under actual process conditions. To
monitor the process seven thermocouples were inserted into the die. Thermal camera was also used for monitoring the die conditions during the open time of the die. Castings were divided into sets of ten pieces for statistical reasons. A few key process parameters were selected based on the basis of earlier knowledge and they were systematically varied during casting experiments. Each cast piece
was marked and later analysed in order to find the dependencies between detected defects and process parameters. Computer simulations of the process were conducted to study the possibility to use numerical simulations for defect prediction. It was found that shrinkage defects could be reasonably well predicted and the influence of the process parameters on their formation was also
apparent. The predictability of surface defects, however, was poor and only indirect conclusions could be made. Observations were made using as cast, ground and polished and cut surfaces from certain sections of the castings. It is very difficult to make any conclusions on surface defect formation based on parameter variation. One reason probably is the too narrow process window, but several promising ideas on the influence of e.g. mould shape, temperature and composition of the graphite coating on the defect formation was discovered.
Compressive Mechanical Properties of Nanostructured Intermetallic Alloys Al3Ti-X (X = Mn or Fe)
Authors: Aguilar-Virgen J.C. , Cabrera A.F. , Umemoto Minoru , Calderón H.A.
Published: March 2009

The mechanical behavior of the sintered nanostructured intermetallic alloys, Al67Ti25Mn8 and Al67Ti25Fe8 has been investigated by means of compression tests as a function of temperature. These intermetallic materials are produced by mechanical alloying and spark plasma sintering. The sintered alloys have been characterized by X-Ray Diffraction and Transmission Electron Microscopy. Their nanostructure consists of a single-phase with an L12 (cubic) structure and an average grain size in the nanoscale (lower than 30 nm). These nanostructured intermetallics show considerably high ductility in compression at high temperature but are brittle at temperatures below 400 °C. In such cases the compressive fracture strength can reach values as high as 1.8 GPa (Al67Ti25Fe8). At 500 °C, some ductility is found together with a relatively high flow stress (around 1 GPa), the corresponding deformation curve shows strain hardening and in some cases stress serrations (strain aging). At 600 °C, a low flow stress is measured (~300 MPa) with high ductility. At 700 and 800 °C, a quasi-superplastic behavior is found with a total deformation of around 45 and very low flow stresses. No evidence of dislocation motion is found at temperatures above 700 °C suggesting a deformation mechanism based on grain boundary sliding.
Micro and Macromechanical Study of Stress-Induced Martensitic Transformation in a Cu-Al-Be Polycrystalline Shape Memory Alloy
Authors: Sánchez F.M. , Pulos G.
Published: March 2009

An experimental investigation of the micro and macromechanical stress-induced
martensitic transformation in a Cu-Al-Be polycrystalline shape memory alloy is undertaken using a uniaxial tension test. Digital images are acquired at different stress states. The image sequences are analyzed to estimate the optical flow to get displacement vector fields. The experiments are carried out on a miniature hydraulic loading device mounted under an optical microscope. The stress-strain
curves and associated images show stress-induced martensitic transformation in specific grains. Displacement vector fields for the polycrystalline shape memory alloy are obtained. They are inhomogeneous due to the martensitic transformation and inter-granular interactions.
Thermal Stability, Structure and Mechanical Properties of TiSiN Coatings Prepared by Reactive DC Magnetron Co-Sputtering
Authors: García-González L. , Morales-Hernández J. , Espinoza-Beltrán F.J. , Muñoz-Saldaña J. , Scholz T. , Schneider Gerold A.
Published: March 2009

TiSiN coatings have been prepared by reactive DC magnetron co-sputtering on Corning glass and carbon steel substrates, using Ti-Si targets, with a constant Si:Ti area ratio of 0.2. The flow rate of nitrogen has been varied from 1.6 to 7.0 sccm, for a fixed argon flow rate of 25.0 sccm. We present a study of structure (texture, crystallite size and microstrain), chemical composition, and mechanical properties of the coatings and their dependence on the argon/nitrogen ratio. Moreover, a study of the thermal stability of the coatings has been performed by means of thermal annealing under oxidizing conditions (air atmosphere) at 500 and 600 °C. Coatings with the smallest crystallite size (∼2 nm) present the highest hardness (26 GPa) and the best thermal stability.
Stabilization Behavior of Heavy Metals Derived from Wastes on Cementitious Minerals and Hydrates
Authors: Ahn Ji Whan , You Kwang Suk , Han Gi Chun , Cho Kye Hong
Published: March 2009

In this paper, the application of wastes as raw materials to cementitious mineral was
investigated. A rolling slag, which contains plenty of heavy metals, was used as a raw material to synthesize calcium sulfoaluminate. It was found that the suitable burning temperature of CSA clinker is between 1,250°C and 1,300°C, and the residual content of heavy metals in the CSA clinker turned out sequentially as Cu, Zn, Cr, and Pb. According to the results of the investigation, it is believed that a large amount of the Cu, Zn and Cr present in the raw materials were fixed in the
CSA clinker formed during the sintering process. It was further found that the distortion of the crystal morphology of hydrate, which was ettringite, took place according to the substitution of heavy metals during the hydration process.
A Comparison of Different Preparation Methods of Fe-Mo-Mg-O Catalyst for the Large-Scale Synthesis of Carbon Nanotubes
Authors: Chen Yan Fang , Lim Yun Soo
Published: March 2009

Carbon nanotubes (CNTs) in a high yield were synthesized by the decomposition of the methane gas with CCVD, in which two different reaction routes of sol-gel method prepared Fe-Mo- Mg-O catalyst. The two different routs influenced the wall number and defects of CNTs and the formation of CNTs. The concentration of Mo in the catalyst played a very important role in the yield of CNTs.
Preparation of Activated Carbon Fibers by Chemical Activation Method with Hydroxides
Authors: Moon Sook Young , Kim Myung Soo , Hahm Hyun Sik , Lim Yun Soo
Published: March 2009

Activated carbon fibers were prepared from stabilized PAN-based fibers by chemical
activation using hydroxides at different concentrations. The experimental data showed variations in specific surface area, microstructure, pore size distribution, and amounts of iodine adsorbed by the activated carbon fibers. Specific surface area of about 2244m2/g and iodine adsorption of 1202mg/g were obtained in the KOH 1.5M. However, the use of NaOH in the activation process rather than KOH and using the same time/ temperature profiles resulted in a carbon with a much
lower surface area. KOH is a more developed pore structure than NaOH, which means that KOH is a better activation agent in producing ACF than NaOH.
Preparation of Porous Hydroxyapatite Scaffolds for Bone Tissue Engineering
Authors: Min Sang Ho , Jin Hyeong Ho , Park Hoy Yul , Park Ik Min , Park Hong Chae , Yoon Seog Young
Published: March 2009

Porous hydroxyapatite (HAp) scaffolds were successfully prepared by using the HAp slurry based on the replication of polymer sponge substrate. The effect of HAp content in slurry on the pore morphology and size, and density, porosity, and mechanical strength of porous scaffolds was investigated. The scaffolds with average pore sizes ranging from 200 to 400 µm had an open, relatively uniform, and interconnected porous structure. As the HAp content increased, the porosity
of scaffold decreased while the density increased. These phenomena were attributed to the fact that the pores became interconnected with more dense and thicker pore walls with increasing HAp content in slurry. The results suggest that the density, porosity, and compressive strength of the porous HAp scaffold were significantly affected by the content of the HAp powder in the slurry.
Synthesis of Biodegradable β-TCP/PLGA Composites Using Microwave Energy
Authors: Jin Hyeong Ho , Min Sang Ho , Hwang Kyu Hong , Park Ik Min , Park Hong Chae , Yoon Seog Young
Published: March 2009

Biodegradable β-tricalcium phosphate (β-TCP)/poly (lactide-co-glycolide) (PLGA) composites were synthesized by in situ polymerization with microwave energy. The influence of the β-TCP content in β-TCP/PLGA composites on the molecular weight, crystallinity, microstructure, and mechanical properties was investigated. As the molecular weight of composites decreased, the
β-TCP content increased up to 10 wt%, while further raising of the β-TCP content above 10%, the molecular weight increased with increasing β-TCP content. This behavior may be ascribed to the superheating effect or nonthermal effect induced by microwave energy. It was found that the bending strength and Young’s modulus of the β-TCP/PLGA composites were proportional to the molecular weight of PLGA. The bending strength of the β-TCP/PLGA composites ranged from 18 to 38 MPa,
while Young’s modulus was in the range from 2 to 6 GPa.
Study on the Biomimetic Properties of Bone Substitute Material: Nanohydroxyapatite/Polyamide 66 Composite
Authors: Wu Lan , Li Yu Bao , Zuo Yi , Zhang Li , Yang Wei Hu , Mu Yuan Hua
Published: March 2009

To compare with the human cortical bone, the biomimetic properties of
nano-hydroxyapatite/polyamide 66 composite (n-HA/PA66) were preliminarily studied qualitatively and quantitatively with TEM, XRD in crystal morphology, phase composition and crystal structure. A series of structure parameters such as cell lattice parameters (a and c), mean crystallite size and micro-strain were calculated to characterize quantitatively the microstructure of n-HA/PA66 and
human cortical bone at the atomic level. The results show that n-HA/PA66 is a good biomimetic biomaterial. But there still are some differences between n-HA/PA66 and human cortical bone. Compared to human cortical bone, the crystal microstructure of n-HA/PA66 is denser, the crystal lattice of n-HA is more perfect and the distortion of crystal lattice decreases.
Microstructures Formed by Charge Ordering Transition in Pr0.55Ca0.45MnO3 and Nd0.5Sr0.5MnO3
Authors: Terai Tomoyuki , Tamai Nobuki , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

We have made crystallographic analysis for microstructures formed by charge ordering transitions in Pr0.55Ca0.45MnO3 and Nd0.5Sr0.5MnO3. From the results, it was found that all interfaces between crystallographic domains of Pr0.55Ca0.45MnO3 are {101}CO ( CO represents a charge ordered phase)
twinning planes and that most of interfaces between crystallographic domains of Nd0.5Sr0.5MnO3 are {112}CO twinning planes. These twinning planes correspond to {110} planes in simple cubic perovskite structure.
Advanced Eco-Materials Processing from By-Products
Authors: Tanaka Toshihiro , Maeda Soichiro , Takahira Nobuyuki , Hirai Nobumitsu , Lee Joon Ho
Published: March 2009

We have tried to develop the following new material processing for the production of
value-added materials from by-products such as kish-graphite, Fe & Cu mixed scraps etc. in steelmaking processes :
1) Production of PdCl2 graphite intercalation compound (PdCl2-GIC) in hydrothermal conditions to create nano-particles encapsulated in kish-graphite.
2) Application of “unusual wetting” of liquid Cu on surface-oxidized Fe to produce composite materials between Cu and ceramics.
Effect of Cooling Rate on As-Cast Texture of Low-Carbon Steel Strips During Rapid Solidification
Authors: Xu Ping Guang , Yin Fu Xing , Nagai Kotobu
Published: March 2009

We investigated the dendrite structures and the as-cast textures of low-carbon steel strips cast at different cooling rates in order to relate the δ-ferrite dendrite structure with the ferrite phase texture. Observations revealed that the orientation intensity of the texture component {111} was stronger than the texture component {001} in the as-cast steel strips obtained at different solidification cooling rates. These two texture components show a roof-shaped variation with the
gradual decrease of the solidification cooling rate, reaching a maximum intensity at a cooling rate of about 2.0 K/s. This suggests that the solidification rate strongly influences the as-cast texture of low-carbon steel strips through changing the δ-ferrite dendrite structure.
Interfaces and Properties of Advanced Materials
Authors: Paidar Vaclav
Published: March 2009

Internal interfaces are decisive for many properties of materials. Both functional and
structural properties of interfaces are briefly reviewed on selected examples. Approaches to the grain boundary classification are discussed in the context of the complex relationship between microstructure and material properties. Implications for grain boundary engineering are mentioned.
Application of 18O2 Exposure–Based Approach to Study the Failure Mechanisms of Oxide Scales on Alumina Formers
Authors: Jedlinski Jerzy
Published: March 2009

The 18O2 exposure-based approach was used to investigate the failure mechanisms of the oxide scales growing on alumina-forming materials. The scale spallation mechanisms and cracking processes were studied at various oxidation stages of FeCrAl alloys and β-NiAl intermetallic compound. High spatial resolution SIMS was applied to determine the distribution of the oxygen isotopes and other elements in the scales. It was found that the scales spall away according to an adhesive mode. However, t is process usually occurs at temperatures high enough to cause the reoxidation of the exposed bare substrat which results in thin oxide film on the metal. The thickness of this film and its composition depend on the alloy and the region at the interface. Spallation on reactive-element free FeCrAl alloys occurs at relatively high temperatures and the film is fairly thick, while on Zr-containing material very thin oxide layer is formed because the scale is better resistant to spalling and this process occurs at quite low temperature. The thin oxide layer formed on smooth regions comprises essentially the alumina, while the sequence of iron, chromium and aluminium oxide appears on regions exhibiting 'oxide imprints'. The applied approach enabled to find that the through-scale cracking observed at early oxidation stages of β-NiAl occurs at high temperatures and not during cooling. Formation of such cracks affects the further growth of the scale in terms of its microstructure, morphology and generation of stresses. Oxygen inward penetration through cracked scales formed during thermal cycling of FeCrAl alloys occurred mainly via oxide grain boundaries.
Preparation and Characterization of Chitosan-Based Scaffolds for Biomedical Applications
Authors: Araújo José V. , Lopes da Silva J.A. , Almeida Margarida M. , Costa Maria Elisabete V.
Published: March 2009

Porous chitosan/brushite composite scaffolds were prepared by a freeze-drying
technique, starting from brushite suspensions in chitosan solutions. The obtained scaffolds showed a regular macroporous and interconnected structure with brushite particles uniformly distributed in the chitosan matrix. The variation of the brushite concentration affected the microstructure of the final freeze-dried scaffold, in particular, its porosity and its average pore size. The yield strengths of
the composite scaffolds could also be improved by the increase of the brushite content.
Effect of Glass Ceramic Crystallinity on the Formation of Simulated Apatite Layers
Authors: Almeida Nuno A.F. , Fernandes Maria Helena F.V.
Published: March 2009

In silicate glasses the kinetics of apatite layer formation is usually rapid but the adhesion to the base glass is poor. Glass ceramics promote a stronger bonding between layer and substrate but decrease the rate of the apatite layer formation. In this work a glass of composition (wt%) 54,89%C3P-24,81%SiO2-20,30%MgO has been studied. This glass was heat treated at four temperatures (840 °C, 870 °C, 890 °C and 910 °C) to obtain glass ceramics with different contents of
the same crystalline phase. A calcium magnesium phosphate phase was formed in all glass ceramics in a volume percent increasing with temperature. The apatite layer precipitated after immersion in simulated body fluid (SBF) formed faster on the glass than on the glass ceramics and a decrease in the amount of apatite formed was observed with the increase in crystallinity. It was generally concluded that heat treatment can turn a reactive glass into glass ceramics of different surface behaviors, from bioactive to quasi bio inert materials.
Mineralization of Titanium Substrates with Different Structures and Surface Finish, Pre-Incubated in Albumin
Authors: Cachinho Sandra C.P. , Marques Paula A.A.P. , Correia Rui N.
Published: March 2009

A study is reported on the influence of surface morphology, chemistry and albumin
adsorption on the in vitro mineralization of titanium. Albumin is the most abundant protein in plasma and was chosen as a pre-incubation medium for titanium substrates previously conditioned by mechanical, thermal and chemical treatment.
Subsequent mineralization studies were performed in carbonated simulated inorganic plasma (CSIP) physiologically buffered with CO2/HCO3 -. The results indicate that surface morphology and albumin adsorption contribute to the development of a B-carbonated apatite deposit and, furthermore, that the buffer system may alter the role of albumin in mineralization.
Study of the Cure of a Diglycidyl-Ether of Bisphenol-a (DGEBA) / Triethylenetetramine (TETA) Epoxy System by Non-Isothermal Differential Scanning Calorimetry (DSC)
Authors: Losada Rosa , Mier José Luís , Barbadillo Fernando , Artiaga Ramón , Varela Angel , Naya Salvador
Published: March 2009

A diglycidyl-ether of bisphenol-A (DGEBA)/Triethylenetetramine (TETA) system was studied by non-isothermal differential scanning calorimetry (DSC) to establish its kinetics of cure. The DGEBA resin was Araldite GZ 601 X75 used in the marine coatings formulations. Previously, the optimum resin/hardener ratio was determined by the reaction heat measuring (.Hc) calculated from the curing exothermic peak. Tests at different heating rates (10, 15, 20, 25 and 30°C/min)
under inert atmosphere were carried out in order to study the reaction kinetics. The activation energy of the cure (Ea) was obtained from these tests data by Borchardt-Daniels, autocatalytic, Duswalt and isoconversional Ozawa methods. Once the activation energy was determined, the master curves method was applied to find the kinetic model which best describes the measured DSC data. The Sestak-Berggren model SB (m,n) was found to be the most adequate for the system studied.
Dispersion of Carbon Nanotubes in Polycarbonate and Its Effect on the Composite Properties
Authors: Leer Carla , Carneiro Olga S. , Covas José A. , Maia João M. , van Hattum Ferrie W.J. , Bernardo Carlos A. , Biró László Péter , Horváth Zsolt E. , Kiricsi Imre
Published: March 2009

The effect of the dispersion state of carbon nanotubes in polycarbonate on the
rheological, mechanical and electrical properties of melt-extruded compounds is presented. The dispersion state was monitored by means of grey values distribution histograms of optical micrographs of the composites. Increasing the processing residence time, and hence the deformation induced by the surrounding polymer, increased the level of dispersion of CNTs in the matrix. This, in turn, resulted in a large improvement of the CNTs reinforcement effect and decreased composite
electrical resistivity. Rheological behaviour is in agreement with these observations.
Photoluminescence of Di-Ureasil Hybrids Doped with Silica Coated Ag Nanoparticles
Authors: Boev Victor I. , Ferreira Rute A. Sá , Nobre Sonia S. , Silva Carlos J.R. , Gomes M.J.M. , Liz-Marzán Luís M. , Carlos Luís D.
Published: March 2009

Photoluminescence of di-ureasil hybrids containing homogeneously dispersed Ag
nanoparticles, covered with silica shells was investigated at room temperature and compared with emission of undoped hybrids. Metal-doped di-ureasils show a broad emission band in the blue spectral region similar to what has been observed in pure di-ureasils but with lower relative intensity. A broad minimum arises around 438 nm for Ag@SiO2 - containing di-ureasils which coincides with the peak of plasmon resonance band in the absorption spectrum. This behaviour can be attributed to inner filtering effect, which manifests itself as absorption by metal nanoparticles of
light emitted from the matrix. Low-temperature time-resolved spectroscopy and lifetime measurements demonstrate that changes are induced in the time-scale behind the di-ureasil host emission when the nanoparticles are incorporated. In particular, the lifetime values for Ag@SiO2- doped di-ureasils are smaller than those measured for the undoped host, suggesting that energy transfer might exist between the hybrid's emitting centres (NH groups and siliceous nanodomains)
and the nanoparticles.
Structural Characterization of Sputtered Composite Stabilized ZrO2 Thin Films
Authors: Portinha Anibal , Teixeira Vasco , Carneiro Joaquim , Newton Rachel , Fonseca H.
Published: March 2009

Zirconia (ZrO2) exhibits three different polymorphic phases as a function of the thermal and pressure conditions (cubic, tetragonal and monoclinic). The use of zirconia coatings at high temperatures requires it to be stabilized at room temperature in order to maintain the high temperature phases when subjected to thermal cycles. For this purpose, this work reports different ways to stabilize ZrO2 coatings produced by DC reactive magnetron sputtering. We have produced stabilized ZrO2 coatings by doping with other metallic and rare earth oxides
(Y2O3 and Gd2O3), depositing nanostructured ZrO2 crystallites in an amorphous Al2O3 matrix and using a ZrO2/Al2O3 nanolaminated structure.
A comparative study of the coatings produced is presented along with their structural stabilization using different approaches. For the doped coatings the tetragonal or cubic phases were obtained as a function of the dopant percentage and for the nanostructured and nanolayered structures the stabilization mechanism is related to the constraining of the zirconia nanocrystallites and the capacity to maintain its size under certain value.
ITO Thin Films on Silicon Buffer by Sol Gel Method
Authors: Hammad Talaat Moussa
Published: March 2009

Sol gel indium tin oxide thin films (In: Sn = 90:10) were prepared by the sol-gel dipcoating process on silicon buffer substrate. The precursor solution was prepared by mixing SnCl2.2H2O and InCl3 dissolved in ethanol and acetic acid. The crystalline structure and grain orientation of ITO films were determined by X-ray diffraction. The surface morphology of the films was characterized by scanning electron microscope (SEM). Optical transmission and reflectance
spectra of the films were analyzed by using a UV-visible spectrophotometer. The transport properties of majority charge carriers for these films were studied by Hall measurement. ITO thin film with electrical resistivity of 7.6 ×10-3 3.cm, Hall mobility of approximately 2 cm2(Vs)-1 and free carrier concentration of approximately 4.2 ×1020 cm-3 are obtained for films 100 nm thick films. The I-V curve measurement showed typical I-V characteristic behavior of sol gel ITO thin films.
Electrolytical Obtaining of Ni-Mo Coatings with Polypyrrole
Authors: Niedbała Jolanta , Budniok Antoni , Łągiewka Eugeniusz
Published: March 2009

Electrolytic coatings Ni-Mo with PPy were obtained by electrodeposition and
electropolymerization from a galvanic bath containing Ni2+, MoO4
2–, ClO4 – ions and pyrrole (Py). The cyclic chronovoltamperommetric curve was used to determine the potential and current density of electrodeposition process. As the electropolymerization is anodic process while the
electrodeposition is cathodic one, the electrode was working alternately as anode and cathode. The process was conducted under alternating potentiostatic or galvanostatic conditions. Comparative tests were carried out for Ni-Mo alloy. The results of structural investigation of the obtained coatings by the X-ray diffraction method show, the Ni-Mo layers are nanocrystalline solid solution of
molybdenum in nickel (α phase), whereas the Ni-Mo+PPy coatings are characterized by decreased peaks coming from Ni-Mo base. Surface morphology of obtained Ni-Mo+PPy and Ni-Mo coatings was investigated by scanning microscope. It was stated, that the coatings obtained by alternating potentiostatic method exhibit multilayer character, whereas the coatings obtained under alternating
galvanostatic conditions are characterized by the presence of Ni-Mo nanoagglomerates plated on polymer surface.
Characterization of Porous Nanostructures
Authors: Sinko Katalin , Torma Viktoria , Pàszli I.
Published: March 2009

Fractal and aggregate structures of porous materials were studied by a variety of the
structure characterization techniques (TEM, small angle X-ray scattering, nitrogen sorption). Scattering data (SAXS, USAXS) for porous materials measured with laboratory equipment and synchrotron technique were interpreted in terms of Guinier, Emmerling, Freltoft, modified Freltoft theories, and simple power law expressions. The evaluation of scattering measurements resulted in
fractal dimensions, sizes of the elementary units, the fractal domains or the aggregates. TEM images confirmed the sizes of the elementary building units, while the pore size distributions could be obtained by nitrogen adsorption. The specific surface area was calculated with respect to the possibility of multilayer formation during nitrogen absorption.
Controlled Synthesis of Morphological Well-Defined BiVO4 Pigment Particles Supported on Glass Substrates
Authors: Cruz Sandra G. , Girginova Penka I. , Neves Márcia C. , Smolka Petr , Kusak Robert , Caldeira Madalena , Teixeira-Dias José , Pedrosa Julio , Trindade Tito
Published: March 2009

An overview of the chemical strategies developed in our laboratories to obtain welldefined
BiVO4 particles is presented. The methods rely on the thermal treatment (including
hydrothermal conditions) of aqueous solutions containing bismuth(III) cations, vanadium(V)
species and organic ligands. The use of distinct polyaminocarboxylates and cyclodextrins as
possible morphological modifiers was investigated. NMR spectroscopic techniques were applied to
the distinct chemical baths in order to have a better insight on the nature of the solute precursors.
Preparation of Photoluminescent Materials from a Lanthanide-Doped Microporous Titanosilicate Precursor
Authors: Lin Zhi , Rainho José P. , Rocha João , Carlos Luís D.
Published: March 2009

The thermal transformation of Eu3+-doped and undoped microporous titanosilicate AM-3 has been reported. AM-3 is stable up to 600 °C and transforms into the analogue of the mineral narsarsukite at 800 °C. The narsarsukite obtained from AM-3 is purer than that prepared from the titanosilicates ETS-10, ETS-4 and AM-1, and is suitable for hosting optically-active Ln3+ ions. The materials have been studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), solid-state magic-angle spinning nuclear
magnetic resonance (MAS NMR), Raman and photoluminescence pectroscopies.
Luminescence and FTIR Spectroscopy of ZnO Nanocrystals
Authors: Grigorjeva Larisa , Millers Donats , Łojkowski Witold , Strachowski Tomas
Published: March 2009

Time-resolved luminescence and Furje Transformation Infrared (FTIR) absorption
spectroscopy for ZnO nanocrystals prepared under different chemical reactions using microwave
driven hydrothermal process was studied. OH- group stretching vibration frequency is considerably
different in nanocrystals studied and in single ZnO crystal. It is shown that fractions of chemicals
used in synthesis process could be found in nanopowders. Luminescence at ~2.0 eV (due to defect
states in ZnO crystals and nanopowders) was suppressed in nanopowders obtained by urea method.
Stable Dispersions of Aromatic Hydrocarbon Colloidal Particles by Laser Ablation
Authors: Köstler Stefan , Rudorfer Andreas , Berghauser Roswitha , Ribitsch Volker , Jakopic Georg
Published: March 2009

Dispersions of colloidal particles of polycyclic aromatic hydrocarbons were obtained by
nanosecond laser ablation. Aqueous suspensions of micron-sized crystals were irradiated with the
second harmonic output of a Nd:YAG laser and converted into colloidal particles. Ionic and nonionic
surfactants were used in the ablation process to stabilise the particles. Dispersions with good
long term stability were obtained. A strong dependence of particle formation rate on laser fluence
was found and the particle formation process is discussed on the basis of UV-Vis spectra and
microscopic examination of the crystals.
Co-Containing LDHs Synthesized by the Microwave-Hydrothermal Method
Authors: Benito Patricia , Herrero Maria , Labajos Francisco Martin , Rives Vicente
Published: March 2009

The synthesis and characterization of Co,Al Layered Double Hydroxides (LDHs)
containing carbonate is reported. The solids have been submitted to several thermal treatments,
hydrothermal and microwave-hydrothermal, modifying both the treatment time and temperature,
with the main aim of studying their influence on the crystallinity of the solids and on the
stabilization of divalent cobalt oxidation state. The results show that whichever the temperature and
time used the only phase detected was the hydrotalcite, and that the cobalt cations keep the divalent
oxidation state.
Encapsulation of Cu(II) Purine Derivative Complexes in NaY Zeolite
Authors: Nunes Natércia , Costa Filomena , Fonseca António Maurício C. , Neves Isabel , Carvalho M.Alice , Ribeiro Cristina
Published: March 2009

The encapsulation of Cu(II) purine derivative complex was carried out by ion exchange
of the complex from aqueous solutions into zeolite NaY. The entrapped complex was characterized
by spectroscopic methods (FTIR and ICP-AES) and surface analysis (XRD). The various
techniques of characterization used show that the Cu(II) complex was effectively encapsulated in
the zeolite and this process does not modify the morphology and structure of the NaY zeolite. These
materials have potential applications in heterogeneous catalysis in mild reaction conditions.
Low Cost Microstructures for Preconcentration of Polar and Non-Polar Organic Compounds
Authors: Silva Lilian Marques , Lima Roberto R. , Carvalho Alexsander T. , Silva Maria Lucia Pereira , Madaleno Joana Catarina , Pereira Luiz
Published: March 2009

Films produced by plasma polymerization of ethyl ether and methyl or ethyl acetate show
good adsorption characteristic for polar and non-polar organic compounds. These films when used
in microchannels machined in a 3D-structure present some preconcentration of organic compounds.
Therefore, the aim of this work is to investigate the physical-chemical preconcentration
mechanisms on this structure. The test molecules used were n-hexane and 2-propanol. Quartz
crystal microbalance and mass spectrometry were used to measure preconcentration. Two different
procedures for reactant injection on the structure were used: a continuous flow during several
minutes or a small amount injected on a single pulse and in a few seconds. The microchannels were
also modified by the introduction of small ceramic particles for enhancement of the flow dispersion.
It was possible to notice for all films a similar kinetic of retention. The main removal mechanism is
adsorption. Although all films can provide the removal of the adsorbents molecules, the most
important characteristic for the adsorption and/or retention is the surface condition. Thus, the
retention of polar compound can be troubled if a non-polar compound was used previously. The
most promising films for retention are ethyl ether and ethyl acetate when n-hexane and 2-propanol
are used as test molecules. The results using n-hexane or 2-propanol point out the use of low-cost
microchannels for preconcentration development.
Application of Volatility Diagrams in the Microstructured Surfacing of Oxide Ceramics
Authors: Souto Alejandro , Rey Pilar , Franco Jaime , Guitián Francisco
Published: March 2009

Thermal treatment of ceramics composed of two or more oxides under controlled
reducing conditions selectively volatilizes the less stable components, leaving microstructured
surfaces consisting of the most stable of the original oxides. Volatility diagrams showing
equilibrium partial pressures allow interpretation of this process and the calculation of equilibrium
conditions for the different reactions involved. In this communication we present results for
ceramics composed of mullite (3Al2O3·2SiO2), zircon (SiO2·ZrO2) and cordierite
(2Al2O3·2MgO·5SiO2).
Structural, Electrical and Dielectric Properties of Uranium Doped Barium Titanate
Authors: Miclea Cornel , Tanasoiu Constantin , Miclea Corneliu Florin , Gheorghiu Anca
Published: March 2009

The influence of uranium doping up to 2 at. % on grain size, electrical resistivity and dielectric constant of barium titanate ceramics has been investigated. The samples were prepared by the conventional ceramic technique using pure raw materials. The mixed oxides were calcined at 1100 oC. The pressed pellets were sintered at temperatures between 13001500 oC in controlled atmosphere of argon and oxygen. The electrical resistivity drastically decreased, from 109 to 103 cm, with increasing uranium content up to 1.5 at. % and increased thereafter to about 107 cm, for 2 at. % U. The dielectric constant slightly increased with increasing U-content, up to about 1 at. % U and then shows a sudden increase with about two orders of magnitude, having a sharp maximum at 1.5 at. % U, when sintered in argon atmosphere compared to only half an order of magnitude when sintered in oxygen atmosphere. The results are discussed in terms of the possible A and B sites occupied by uranium as well as the boundary layer enriched with vacancies.
Polynuclear Molybdenum and Tungsten Complexes containing 3-Hydroxypicolinic Acid and Europium (III)
Authors: Rodrigues Manuela J.E. , Paz Filipe A. Almeida , Ferreira Rute A. Sá , Carlos Luís D. , Nogueira Helena I.S.
Published: March 2009

Novel polynuclear tungsten and molybdenum (VI) complexes with 3-hydroxypicolinic
acid (HpicOH) and europium(III) [M4O12Eu(picOH)3] (M(VI) = W, Mo) were prepared by
hydrothermal methods. The solid compounds were characterized by FT-IR and FT-Raman
spectroscopy and elemental analysis. The photoluminescent properties of the materials were
investigated, showing sensitization of the europium(III) luminescence by both the 3-
hydroxypicolinate ligand and the polyoxometalate moiety
Stabilisation of CuO Aqueous Suspensions
Authors: Guedes Mafalda , Ferro Alberto C. , Ferreira José Maria F.
Published: March 2009

Obtaining ceramic bodies with enhanced mechanical properties via colloidal processing
requires efficient dispersion of the ceramic powders. In this work, the dispersive effect of three low
molecular weight quaternary ammonium hydroxides with different alkyl groups upon stabilisation
of CuO aqueous suspensions is studied and compared with that of Tiron, a compound based on the
benzene molecule. The purpose is to illustrate the effect of molecular structure, size and charge
location upon dispersing effectiveness. To access these parameters, rheological and electrophoretic
measurements using both bare and surface charge modified CuO were made. Tiron® revealed to be
the most efficient dispersant for CuO in water, rendering viscosity values below 1 Pa⋅s and the
highest variation in zeta potential amplitude.
Iron Oxide and Oxide-Hydroxide Nanoparticles in Organic-Inorganic Matrices
Authors: Silva Nuno João O. , Millan Angel , Amaral Vitor S. , Palacio Fernando , Fu Lianshe , Carlos Luís D. , de Zea Bermudez V.
Published: March 2009

Nanometric ferrihydrite, maghemite and magnetite particles formed within an organicinorganic hybrid matrix were obtained by the sol-gel process. In contrast to precipitation techniques, sol-gel process appears as suitable way to achieve size-controlled nanoscopic magnetic particles anchored in a hybrid structure. The hybrid matrix here reported, named di-ureasil, is composed of poly(oxyethylene) chains grafted to siloxane groups by means of urea cross-linkages. The formation of ferrihydrite particles was achieved incorporating iron nitrate during the sol-gel
process, at low pH. The formation of maghemite takes place after the incorporation of a mixture of Fe3+ and Fe2+ ions and treatment with an ammonia solution, after the sol-gel process. Magnetite nanoparticles are formed after the incorporation of Fe2+ ions and treatment with ammonia at 80°C. The AC magnetic susceptibility shows thermal irreversibility with a blocking temperature TB≈13K and ≈25K depending on frequency for the ferrihydrite and maghemite particles, respectively. The
magnetite nanoparticles are blocked at room temperature. Above the irreversibility the magnetization of ferrihydrite and maghemite follows a Langevin function modified with a linear term, as found in antiferromagnetic and ferrimagnetic particles.
Evolutional Friction Law in the Numerical Simulation of the Deep Drawing of a Rail
Authors: Oliveira Marta C. , Alves José Luis , Menezes Luis Filipe
Published: March 2009

One of the most relevant technological parameters for the accurate numerical simulation
of the deep drawing process is friction, since the contact between the blank sheet and tools develops
friction forces that act as supplementary boundary conditions that determine the final part shape.
Most applications reported in literature are still restricted to Coulomb’s law with a constant friction
coefficient over the entire process. Although it is consensual that state conditions of contact surfaces
and consequently the friction behaviour are influenced by a large number of parameters, there is no
agreement about a wide-ranging law to accurately describe the friction evolution. One possibility is
to use phenomenological laws that accurately fit experimental data. A Voce type law is used in this
work to describe the evolution of the friction coefficient over the entire process as function of the
contact pressure. This type of law guarantees a good correlation with experimental data and also
numerical stability. The Voce type law was implemented in the static implicit code DD3IMP. The
analysis of the relevance of considering the evolutional friction law in the numerical simulation is
performed for a U-rail. This shape was selected for this study due to the simple deformation
mechanisms that are involved, but also because it is a rail specially conceived to emphasize 2-D
springback defects. The blank sheet material selected is a 6016-T4 aluminium alloy. The plastic
behaviour is modelled using the 1948 Hill’s criterion with isotropic and kinematic hardening. The
numerical results obtained considering the evolutional friction law are compared with two other
results obtained with: (i) a constant friction value of 0.10, normally used for this material in
industrial practice and (ii) three constant friction coefficients for each contact zone (flat, die radius
and punch radius).
New Method for Material Classification from TGA Data by Nonparametric Regression
Authors: Naya Salvador , Cao Ricardo , Artiaga Ramón , García Ana
Published: March 2009

The application of nonparametric method of functional regression for the classification of
different types of materials studied by thermo-gravimetric analysis is proposed in this work. The
method is illustrated with two case studies for classifying different materials. Some simulation
study shows the performance of the method when the correlation between groups parameters and
the error variance change.
On the Possibility to Observe a Compensation Effect around the Glass Transition Temperature
Authors: Neagu Rodica M. , Marat-Mendes José N. , Neagu Eugen R.
Published: March 2009

Compensation has been reported for the relaxation parameters: the activation energy W
and the pre-exponential factor τ0, determined from the Thermal Sampling of Thermally Stimulated
Depolarization Current technique. Below the glass transition it is assumed that the relaxation time
follows an Arrhenius equation. In the vicinity of glass transition temperature an experimental
thermogram may be analyzed using the Vogel-Fulcher-Tamman-Hesse (VFTH) or the Williams-
Landel -Ferry equation. In this article we use the VFTH relationship to study the compensation
effect in the range of glass transition. For an elementary peak obtained by TS there is a
relationship between the activation energy W, the temperature of the maximum current Tm, the
VFTH temperature, the compensation temperature Tc and the compensation time τ
c. We employ this
relationship for a basic analysis of the compensation effect in the temperature range around Tg. By
numerical simulations, and assuming parameters similar to those measured experimentally, we
show that it is possible to observe a compensation point in some well defined conditions
New Fluorescent Heterocyclic Materials: Synthesis, Solvatochromic and Fluorescence Properties
Authors: Costa Susana P.G. , Batista Rosa M.F. , Sousa Ana M. R. C. , Raposo M. Manuela M.
Published: March 2009

Thienyl- and bithienyl-1,3-benzothiazoles 1 and 2 were synthesised by reacting various formyl thienyl and bithienyl derivatives with o-aminobenzenethiol in moderate to excellent yields. Evaluation of the solvatochromic and fluorescence properties of these compounds was carried out. Due to their strong fluorescence and also the strong push-pull character, benzothiazole derivatives 1 and 2 can be used as potential NLO materials or as fluorescent markers.
Strain and Stress Distribution in Vickers Indentation of Coated Materials
Authors: Antunes Jorge M. , Sakharova Nataliya A. , Fernandes José Valdemar , Menezes Luis Filipe
Published: March 2009

Depth sensing indentation equipment allows the mechanical properties of thin films to be
easily determined, particularly the hardness and Young’s modulus. In order to minimize the
influence of the substrate on the measured properties, the indentation depth must be limited to a
small fraction of the film’s thickness. However, for very thin films, the determination of the
contribution of the substrate and the film to the measured mechanical properties becomes a hard
task, because both deform plastically. The numerical simulation of ultramicrohardness tests can be a
helpful tool towards better understanding of the influence of the parameters involved in the
mechanical characterization of thin films. For this purpose, a three-dimensional numerical
simulation home code, HAFILM, was used to simulate ultramicrohardness tests on coated
substrates. Materials with different Young’s modulus film/substrate ratios were tested. Analyses of
strain and stress distributions for several indentation depth values were performed, in order to
clarify the composite behaviour.
Stress Corrosion Cracking of Austenitic Stainless Steel Alloys for Reinforced Concrete
Authors: Correia Maria J. , Salta Manuela M.
Published: March 2009

The corrosion resistance under mechanical stress can be one of the most concerning types
of localized corrosion for the application of stainless steel reinforcements in concrete. This paper
will assess the stress corrosion cracking susceptibility, by the slow strain rate test method (SSRT),
of three austenitic stainless steel alloys: one conventional Fe-Cr-Ni base alloy and two new
composition Fe-Cr-Mn base alloys adequate to the manufacturing of ribbed bars for reinforcing
concrete. The SSRT results show that only one of the austenitic Fe-Cr-Mn alloys is susceptible to
stress corrosion cracking while the other shows a performance similar to that of the AISI 304
stainless steel alloy.
Developments for Rapid Tooling Application in Sheet Metal Forming
Authors: Baptista Rui , Silva M. Beatriz , Saraiva Carlos
Published: March 2009

The market is changing very quickly, demanding the companies the capability of
producing better and/or more performing products. This changing market leads the companies to be
more flexible and agile. In particular, for the tool makers and the stamping companies, they are
requested to participate in the design phase of the product and process, as well as to produce
prototypes and small series in very short time and with low costs.
To answer to these demands in the stamping steps design and consequently in the tool design,
several finite elements packages are widely used, allowing the tool designers to foresee the results
of their options/decisions without the need to manufacture and test tools, with the inherent
excessive cost of money and time. Following this methodology, CAE analysis, the final phase of
tool try out, always necessary, will be certainly shorter and less expensive, once they start with a
solution quite more worked and, for sure, closer to the final solution.
In this industrial context, appeared the great motivation for the development of competences on the
rapid manufacturing of stamping tools (active elements: punch, die and blankholder), on the
numerical simulation of the process and, on the development of the modular tool concept.
In this paper the main results of the development of these areas of research, are presented. In
particular, the use of the numerical simulation, using PAM-STAMP 2G software, for the validation
of the stamping phases, the realisation of laboratorial stamping tests using tools produced by the
several techniques available on Portugal for rapid prototyping. At the same time, it was developed
the modular tool concept, i.e., a tool in which by fast and easy change of the active elements,
different parts can be formed. The active elements of the tool have been manufactured by several
rapid tooling techniques, like DMLS - Direct Metal Laser Sintering, LOM - Laminate Object
Manufacturing, HSM – High Speed Milling and also the machining of non-traditional materials
such as nylon, ureol and aluminium. Some inserts have been produced by indirect techniques such
as reinforced resins (polyurethane, epoxy and urethane) using shells produced by SLstereolithography.
Finally some conclusions are drawn.
Effect of the Consolidation Technique on the Sintering Ability and Thermal Properties of AlN Processed from Aqueous Suspensions
Authors: Olhero Susana M.H. , Ferreira José Maria F.
Published: March 2009

In this work, two different consolidation techniques were used to obtain AlN samples:
slip casting and dry pressing of granules obtained from aqueous suspensions by freeze granulation.
The green samples were sintered at a temperature (1750°C) lower than those usually used
(>1800°C), using CaF2 and YF3 as sintering aids. The microstructural features were analysed by
scanning electron microscopy (SEM) and the crystalline phases formed were identified by X-ray
(XRD). Full dense AlN-based ceramics were obtained from both consolidation techniques; however
the thermal conductivity values were quite different. The presence of carbon in the samples derived
from the freeze granulated powder containing organic processing additives de-waxed in an inert
atmosphere revealed to be helpful in the cleaning of oxygen present at the grain boundaries and
consequently, for enhancing the thermal conductivity.