bluuebunny/crossref_metadata_2025 huggingface dataset:
Semiconducting YBCO Thin Films for Uncooled Terahertz Imagers
Authors: Longhin Mattia , Kreisler Alain J. , Dégardin Annick F.
Published: March 2009

The terahertz domain (500 GHz - 5 THz) has been object of unceasing research activities,
due to the wide range of conceivable applications in these fields. This study focuses on the
development of semiconducting YBa2Cu3O6+x (YBCO) thin films to be used as sensitive elements
on future uncooled terahertz imagers working on a thermal principle. YBCO thin films have been
hollow-cathode sputtered on MgO single-crystals under different conditions. Electrical and
structural characterizations have then been carried out. The resistivity of the thin films and the
temperature coefficient of resistance (TCR) have been determined. X-ray diffraction and atomic
force microscopy analyses have then been performed. If compared with materials currently used as
sensing element in commercial near-infrared imagers, electrical characterization shows values of
the TCR comparable to amorphous silicon and almost two times better than VOx-compounds.
Marine Precursors-Based Biomorphic SiC Ceramics
Authors: López-Álvarez Miriam , Rial Lourdes , Borrajo Jacinto P. , González Pio , Serra Julia , Solla Eugenio Luís , León Betty , Sánchez J.M. , Martínez-Fernández Julian , de Arellano-López A.R. , Varela-Feria Francisco M.
Published: March 2009

Biomorphic silicon carbide ceramics is very promising as a natural base material for
biomedical applications due to their excellent mechanical-biochemical properties and biocompatible
behaviour. This innovative material is produced by molten-Si infiltration of carbon templates
obtained by controlled pyrolysis of biological precursors. The final product is a light, tough and
high-strength material with predictable microstructure.
In this study the possibility to produce biomorphic silicon carbide ceramics using marine precursors
is demonstrated. Due to the great biodiversity offered by the marine medium, a previous selection
of algae (Laminaria ochroleuca Bachelot de la Pylaie, Undaria pinnatifida (Harvey) Suringar,
Saccorhiza polyschides (Lightfoot) Batters and Cystoseira baccata (Gmelin) Silva) and marine
plants (Zostera marina L. and Juncus maritimus L.) was carried out, taking into account its
microstructure, porosity and interconnectivity of each species.
The bioceramization process was evaluated in three phases: original material analysis, pyrolysis
process and reactive melt Si-infiltration. For each marine precursor, a detailed study by Scanning
Electron Microscopy (SEM) of the natural material, the carbon preform and the final SiC
biomorphic product is described. The viability to obtain biomorphic SiC ceramic material for all the
selected marine precursors is discussed.
Rare Earth Metal Doped Barium Titanates
Authors: Radoczy T. , Kovacs Kristof , Sarzo N.
Published: March 2009

High purity as well as Ce-, Pr- and Y-doped polycrystalline BaTiO3 ceramics were
prepared by wet chemical synthesis. Dielectric constant as well as dielectric loss of dry pressed and
sintered ceramics show dielectric constant above 20000 for samples containing 0.5 % Ce
accompanied by semiconducting properties. X-ray diffraction studies confirmed Ti being
substituted by Ce an Y, while Pr substitutes Ba ions.
Examine of Mechanical Load of Silicone Rubber by Optical Methods
Authors: Bojtos Attila , Valenta László
Published: March 2009

Silicone rubber is an essential construction material in food industry, medicine and in
some fields of mechanical engineering, because it has special mechanical, electrical, biological and
other special properties. Over the usage of silicone rubber as structural material, the “intelligent”
behaviour is more and more important. In this case the question arises whether its optical properties
change by the effect of mechanical load or deformation? Can it be used like sensor, utilizing these
properties?
The paper shows the newest result of our optical research in connection with silicone rubber and
shows the possibility of its usage for optical strain and force sensor, using its birefringence.
Transformation of Temperature and Time Diagrams Constructed by Different Time Intervals Applying the Newton Formula
Authors: Dudás Zoltán
Published: March 2009

This document explains and demonstrates two simple approximation methods based on
the Newton formula. The first method makes possible the transformation of whole temperature-time
interval diagrams into temperature-time diagrams to help the comparison of the diagrams. The
second shows a way how
Weldability Investigation of Temper-Grade Steels
Authors: Lengyel Gábor , Palotás Béla
Published: March 2009

The mechanical properties of temper-grade steels can be modified in a wide range by
heat treatment. The principle of heat treatment lies in the good hardenability, so when such steels
are welded it is very likely that the heat affected zone is hardened. Considering the fact that in the
case of design simplifications it may be needed to weld temper-grade steels, as well therefore it is of
crucial importance to eliminate cold cracking. There are many methods available to determine
preheat temperature. The applicability of methods for determination of preheat temperature was
checked by experimental welding for both two and three dimensional heat conduction. According to
our experience the different methods cannot be applied in general namely they are valid only under
certain conditions.
A Two-Dimensional Cellular Automaton Simulation for the Description of the Austenitization in Hypoeutectoid and Eutectoid Fe-C Steels
Authors: Karacs Gábor , Roósz András
Published: March 2009

The following two-dimensional model describes the process of isothermal austenitization
in the hypoeutectoid and eutectoid unalloyed steels. The initial lamellar structure of simulations is
similar to the real structures. The interlamellar spacing – and at the same time the thickness of
lamellas – can be changed arbitrarily and some lamellas can be cracked. The process of nucleus
formation is described by a model of free enthalpy basis that makes a difference between the
locations of nucleus formation in accordance with their free enthalpy. The nucleus growth is
described by the numerical solution calculated by the Fick II. diffusion equation by using the
Cellular Automaton method in the course of the simulations.
Analysis of Mechanical Behaviour of Tendon Implant by Using Numerical Method
Authors: Molnár László , Paróczi Annamária
Published: March 2009

The structural improvement of tendon implant is running in frame of a research project at
our department for 3 years. The main goal is to improve a tendon implant construction which has a
tensile stiffness similar to the sound tendon. The tendon implant developed on such way that
implant should be able to take over the functions of a sound tendon. To reach this goal firstly the
measurement results of tensile stiffness of cadaver tendons were evaluated. The tensile tests of
cadaver tendons happened in earlier phase of this research. Beside the aim of enhance the tensile
stiffness of the implant was a second request that we need to change the place of maximal
mechanical stress from end of implant to inside of the implant. To enhance the mechanical
behaviour (tensile stiffness) of implant the type of matrix material along longitudinal and radial
directions as well as the length of the fibre in the silicone implant were modified.
Improvement of construction was performed by numerical simulation using ANSYS. At first we
prepared 2D and 3D geometry models on which the tensile analysis was evaluated. Improvement of
the construction was supported by a concentrated spring model also which helped us to check the
resultant stiffness of the construction. It was successful to increase the stiffness of the original
implant with fibre reinforcing. We reached with the new construction (with one reinforcing fibre)
almost half of an average cadaver tendon’s tensile stiffness.
Electropolishing of Coronary Stents
Authors: Gellér Zsuzsa Edina , Albrecht Katalin , Dobránszky János
Published: March 2009

Produce of coronary stents demands advanced precision. In the present study, electropolishing
was performed on stainless steel slotted tube coronary stents made by laser cutting. The
surface quality of stents has a significant influence on biocompatibility, therefore the optimal
method for electropolishing were explored. Additionally, acid pickling as the pretreatment of electropolishing
was also conducted. Pickling was necessary prior to electropolishing for decreasing
roughness of the cutting zone and for removing the oxide films covering the stent surface. An optimal
condition for electropolishing could also be established and it caused a smooth stent surface.
Material removal (weight loss and strut width change) in the process of both pickling and electropolishing
was investigated. Furthermore, material characterization of the stents was determined by
means of composition analysis, metallographic characterization and microstructural analysis.
Surface Analysis after Shot Peening Processing of ENAW 7075 Aluminium
Authors: Grum Janez , Zupanc Uros
Published: March 2009

Shot peening has been a very important and well-known surface cold-hardening process applicable to various machine parts and tool surfaces for quite a long time since it improves fatigue strength and corrosion resistance of stressed surfaces. Hardening by shot peening provides, because of plastic deformation, an increase in hardness and induces compressive residual stresses in the thin surface layer, which reduces material fatigue and prevents the generation and propagation of cracks. The present paper reports of results of shot peening hardening of specimens made of 7075-T651 aluminium. They were surface-hardened by steel shots M170 with Almen hardening intensity of 8A and 12A respectively and by glass beads GP165 with Almen hardening intensity of 12A. The steel shots and glass beads had the same diameter but differed considerably in hardness and density. The surface condition after shot peening processing was assessed in terms of surface integrity, which establishes a relation between processing conditions and roughness state and hardened-layer depth supported by an analysis of residual-stress variations.
The Investigation of Thin Protecting Layers on Roughened Galvanized Steel Surfaces Produced by Different Coating Methods
Authors: Németh Péter , Csanády Ágnes , Papp Katalin , Pintér Anna C. , Szabó László , Pászti Zoltán , Tóth Attila Lajos , Kálmán Erika
Published: March 2009

Protective, chromate substitute thin layers on roughened galvanized surfaces produced at OCAS
(Arcelor, Belgium) were characterized and compared using Scanning Electron Microscopy
(SEM+EDS), Atomic Force Microscopy (AFM), Nanoindentation and X-ray Photoemission
Spectroscopy (XPS). EDX maps, line scans and point analyses obtained at various places of the
surfaces have shown differences between the CVD and silane nanolayers in the matter of thickness
distribution and composition. At cross-section specimens the thickness of the layers could be
shown. The hardness differences caused by layer thickness variations are hard to follow by
nanoindentation as the penetration depth of the indenter is much larger than the thickness of the
coatings. XPS measurements can distinguish between the chemical states of silicon in CVD and
silane coatings.
Investigation of Plasticizing Admixtures Used in Hungarian Building Industry
Authors: Takács Márton
Published: March 2009

There is no doubt that concrete makes a massive contribution to sustaining the quality of
life. Properties of concrete can be expediently modified by adding special chemical materials called
admixtures. Admixtures for concrete are now widely accepted as materials that contribute to the
production of durable and cost-effective concrete structures [1]. Plasticizing admixtures reduce
water needed to achieve a given workability of the fresh mix. This main effect can be utilized in
three ways: increased strength, increased workability, or economies in mix design [2].
In this research work effect of type and dosage of different plasticizing admixtures available in
Hungary were investigated in detail. Standard test methods such as flow table test, compressive test,
and shrinkage test were applied to obtain effectiveness of the admixtures. Results were compared
with the requirements of the harmonized admixture standard MSZ EN 934-2:2002.
Biopolymer-Hydroxyapatite Nanocomposite from Eggshell for Prospective Surgical Applications
Authors: Balázsi Csaba , Bishop Aisha , Yang Jason , Sedlácková Katarína , Wéber Ferenc , Gouma Pelagia Irene
Published: March 2009

From biological perspectives, biopolymer - hydroxyapatite nanocomposites for tissue replacement
interact with the surrounding in vivo environment chemically, mechanically and morphologically.
Hydroxyapatite (HA) is a natural ceramic operable as a biocomposite coating to improve the
biocompatibility of implant substrates. To fulfill this requierements hydroxyapatite added
biodegradable scaffold were prepared by electrospinning method to enhance biological
functionality. In this work, firstly a novel synthesis of the hydroxyapatite nanocrystals prepared
from eggshell are presented. Polymer based composites were prepared by electrospinning
hydroxyapatite with a biocompatible polymer for the development of a structurally stable casing for
prosthetic devices.
SOI-LEDs with Carrier Confinement
Authors: Hoang Tu , Holleman Jisk , Schmitz Jurriaan
Published: March 2009

Silicon-On-Insulator (SOI) technology exhibits significant performance advantages over
conventional bulk silicon technology in both electronics and optoelectronics. In this chapter we
present an overview of recent applications on light emission from SOI materials. Particularly, in our
work we used SOI technology to fabricate light emitting diodes (LEDs), which emit around
1130 nm wavelength with an external quantum efficiency of 1.4 × 10−4 at room temperature
(corresponding to an internal quantum efficiency close to 1 %). This is almost two orders of
magnitude higher than reported earlier for SOI LEDs. This large improvement is due to three carrier
confinement mechanisms: geometrical effects, quantum-size effects, and electric field effects. Our
lateral p+/p/n+ structure is powered through two very thin silicon slabs adjacent to the p+/p and n+/p
junction. Such use of thin silicon films aims to reduce the p+ and n+ contact area and to confine the
injected carriers in the central lowly doped p-region. With this approach, we realized an efficient
compact infrared light source with high potential switching speed for on-chip integration
applications.
The Effect of the Processing Temperature on the Microstructures of Pr-Fe-Co-B-Nb HDDR Magnets
Authors: Silva S.C. , Ferreira Eliner Affonso , de Faria Jr. Rubens Nunes , Takiishi Hidetoshi
Published: March 2009

Pr14FebalCoxB6Nb0.1 magnets have been produced using the hidrogenation
disproportionation desorption recombination (HDDR) process. The effect of the Co content (x= 0,
4, 8, 10, 12, 16) and the reaction temperature (800-900 °C) on the microstructure and magnetic
properties of the HDDR material have been investigated. The processing temperature
(desorption/recombination) affected the microstructure and magnetic properties of the bonded
magnets. The alloy with low cobalt content (4 at.%) required the highest reaction temperature
(880°C) to yield anisotropic bonded magnets. The optimum temperature for alloys with 8 at.% Co
and 10 at.% Co were 840°C and 820°C, respectively. Alloys with high cobalt content (12 at.% and
16 at.%) were processed at 840°C. Each alloy required an optimum reaction temperature and
exhibited a particular microstructure according to the composition. Pr14Fe80B6Nb0.1 magnets have
been processed for comparison.
Effect of Milling Parameters on the TiB and TiB2 Formation in Ti-50at%B and Ti-66at%B Powders
Authors: Silva Gilbert , Ramos Erika Coaglia Trindade , Ramos Alfeu Saraiva
Published: March 2009

This work discusses on the effect of milling parameters on the TiB and TiB2 formation in
Ti-50at%B and Ti-66at%B powders, respectively. Both powder mixtures were processed in a
planetary ball Fritsch P-5 ball mill under Ar atmosphere, varying the milling parameters: rotary
speed (150 and 200 rpm), size of balls (10 and 19mm diameter) and ball-to-powder weight ratio
(2:1 and 10:1). In order to obtain the equilibrium structures the milled powders were heated at
1200oC for 1h. Samples were characterized by X-ray diffraction (XRD), scanning electron
microscopy (SEM), and thermal analysis (DSC). XRD results indicated that extended Ti(B) solid
solutions were formed during ball milling of Ti-50at%B and Ti-66at%B powders. After milling for
170h it was noted the TiB and TiB2 formation in Ti-50B and Ti-66B powders processed under
higher-energy condition. DSC analysis revealed that the TiB2 formation was completed during
heating of mechanically alloyed Ti-66at%B powders only. After heating at 1200oC for 1h, a large
amount of TiB and TiB2 was found in Ti-B powders milled under higher energy condition.
Binder System for Coarse Powders Processed by Metal Injection Molding (MIM)
Authors: Nogueira A.P.G. , Machado Ricardo , Wendhausen Paulo A.P. , Portaluppi Diego Fernando
Published: March 2009

Research on determined alloys produced by metal injection molding has been done for cost
reduction purposes through the use of powders with bigger particle size. However, regarding feedstock
homogeneity, certain limitations are presented when coarse particles are used. For instance, homogeneity
strongly influences rheological behavior of the feedstock and dimensional control of the sintered part.
Therefore, the purpose of this work was to evaluate effectiveness of a modified binder system with the
addition of a surfactant polymer which makes the feedstock more homogeneous. This study was carried
out on a FeNiP alloy currently processed by MIM, where 50%wt of the iron powder was replaced with
course powder having a particle size distribution of D90 less than 47 ,m. Effectiveness of binder
systems using a Melt Flow Index (MFI) and the behavior of dimensional accuracy at sintered part were
analyzed. Results showed more feedstock homogeneity and less dimensional deviation when a surfactant
agent was used.
The Study of Prototypes of Dental Implants Obtained by the Titanium Powder Injection Molding Process: In Vivo Study
Authors: Schaeffer Andreas , Schaeffer Lírio , Pereira Padilha Dalva Maria , Futterleib Alexandre , Baroni Alexandre
Published: March 2009

The production of titanium parts from powder metallurgy is one of the tendencies of
modern metallurgy, since it allows obtaining structures with complex geometries and controlled
porosity. The purpose of this study was to produce two types of dental implant prototype, and
compare them biologically. Smooth surface prototypes were obtained, by the conventional turning
process and porous surface prototypes using Metal Injection Molding (MIM). The prototypes were
implanted in rats that were euthanized after 3 weeks, and the bone/implant interface was analyzed.
The results showed that all prototypes were clinically stable at the end of the healing period, but
those produced by the MIM process presented a significantly higher percentage of osseointegration
(bone/implant contact) than the milled prototypes in the same healing period. It is concluded that
the bone tissue grew independent of type of implant, enabling quick, rigid fixation already in the
third week of the healing process.
Sintered High Carbon Steels: Effect of Thermomechanical Treatments on their Mechanical and Wear Performance
Authors: Martinez M.A. , Calabrés R. , Abenojar J. , Velasco Francisco
Published: March 2009

In this work, ultrahigh carbon steels (UHCS) obtained by powder metallurgy with CIP
and argon sintered at 1150°C. Then, they were rolled at 850 °C with a reduction of 40 %. Finally,
steels were quenched at 850 and 1000 °C in oil. In each step, hardness, bending strength and wear
performance were evaluated. Obtained results are justified with a metallographic study by SEM.
Both mechanical properties and wear resistance are highly favoured with the thermomechanical
treatment that removes the porosity of the material. Moreover, final quenching highly hardens the
material. The obtained material could be used as matrix for tool steels.
Metallography Parameters Study of Fe-6.5wtSi Alloy Obtained by Spray Forming
Authors: Rodrigues F.L. , Soares M.A. , Silva Maria do Carmo , Bolfarini Claudemiro , Sobral M.D.C.
Published: March 2009

Silicon-iron alloys with silicon content about 6.5wt.%Si offer a great potential for
applications aiming reduction of core loss in electric parts. Deposits of the Fe-6.5wt%Si alloy
produced by spray forming were annealed at temperatures between 400 and 1300oC, during 1h in
vacuum. The grain size has a great importance to the magnetic properties. In the present work, it
was analyzed the influence of the metallography parameters in order to get the best accuracy to
determine the grain size according to ASTM 112-96. Chemical composition, time and
temperature of specific etchings were modified and tested in different conditions of observation
in light microscopy. Bright field, polarized light and dark field were used in the samples aiming
to measure the grain size. The best etchings were Nital 10% and Marshall, both at room
temperature. The results of grain measurement are presented in their relationship with the
magnetic properties.
Centrifuge Study on Influence of Particle Size, Compression and Substratum on Particle-Surface Adhesion Force
Authors: Felicetti M.A. , Coury José Renato , Aguiar M.L.
Published: March 2009

The centrifugal technique was used to investigate the influence of particle size, applied
compression and substrate materials (stainless steel, glass, Teflon® and PVC) on particle-surface
adhesion force. Phosphate rock and manioc starch particles were used in a microcentrifuge that
contained specially designed centrifuge tubes and reached a maximum rotation speed of 14,000
rpm. The profile of adhesion force followed a log-normal distribution and adhesion force increased
linearly with particle size and the increment of the compression force. The manioc starch particles
presented adhesion forces greater than those for the phosphate rock particles for all particle sizes
studied. The glass substrate showed a higher adherence than other materials, most probably due to
its hardness and polishing.
3Y-TZP/Si2N2O Composite Obtained by Pressureless Sintering
Authors: Santos Carlos A. Xavier , Hayakawa Motozo , Bressiani José Carlos
Published: March 2009

Y-TZP presents excellent properties at room temperature but these properties decrease as
the temperature increases. This paper studies the behavior 20vol%Si3N4-SiC when added in YTZP
matrix and heated under no pressure system. Al2O3 and Y2O3 were used to maintain the stability of
the matrix and as sintering aids. The addition of Si3N4 and SiC in a Y-TZP matrix leads to
formation of silicon oxynitride and it increases the mechanical properties like toughness and
hardness. The mixture was milled and molded by CIP. Samples were heated at 1500°C, 1600°C and
1700°C for 2h without pressure under atmospheric conditions in bed-powders of Si3N4. Samples
were characterized by XRD. Density, hardness, toughness, bending strength were measured. The
structure of the material was observed in SEM/EPMA to verify the distribution of the materials in
the composite. The formation of Si2N2O was observed in the sintered material and it showed an
increment of both hardness and toughness as temperature increases. The samples presented
considerable resistance of oxidation at 1000°C.
Study of Operational Conditions for the Precipitated Calcium Carbonate Production
Authors: Silva Souto Eliane Cristina , Damasceno João Jorge Ribeiro , Hori Carla Eponina
Published: March 2009

Calcium carbonate (CaCO3) is a natural occurring mineral or it can be produced by
chemical means. This last product is often referred to as Precipitated Calcium Carbonate (PCC).
PCC has various advantanges since it exhibits higher brightness and opacity. There can be
considerable variation in the properties of the PCC depending upon the process conditions used to
prepare it. In this work, the effect of different factors on the particle size of PCC has been
investigated. The experiments were performed by bubbling CO2 in slaked lime suspensions. The pH
of the lime slurry was 12 or higher at the beginning, but it decreased, down to an equilibrium pH of
8± 1, when the reaction was considered complete.
Silicon Carbide Whiskers Interference on Silicon Nitride Based Composite
Authors: Baldacim Sandro Aparecido , dos Santos Claudinei , Silva Olivério Moreira Macedo , Silva Cosme Roberto Moreira
Published: March 2009

Silicon nitride based composite has been prepared, using a direct mixture process as
alternative route. Silicon carbide whiskers were mixed directly to silicon nitride based powders
containing yttrium and neodymium oxide as sintering aids. Uniaxial hot pressing was used to
prepare sintered samples. Crystalline phases were identified using x-ray diffractometry.
Intergranular phases were analyzed using Scanning Electron Microscopy. Some mechanical
properties (microhardness and fracture toughness) were also evaluated. The obtained high values of
fracture toughness were correlated to the activation of toughening mechanisms, such as crack
bridging and crack deflection.
Sintering of Commercial B4C with Synthesized B4C Additions
Authors: da Rocha Rosa Maria , Gutierres Jonas S. , de Melo Francisco Cristóvão Lourenço
Published: March 2009

Boron Carbide is a ceramic material of technological application due to its extreme
hardness and high chemical and thermal stability. The effect of synthesized boron carbide addition
on pressureless sintering and hot-pressing of a commercial B4C was investigated. B4C synthesized
by carbothermal reduction using carbon black as carbon source was mixtured in 10, 30 and 50 wt%
to a commercial B4C. Powder mixtures were compacted into pellets and sintered by pressureless
sintering at 2050 °C/30min Samples were compared to a pure commercial B4C and characterization
results have not showed great differences. Relative densities of as-sintered materials exceed 93% of
theoretical for all compositions and microhardness Hv of ∼ 32 GPa was obtained.
High and Room Temperature Mechanical Evaluation of SiC Ceramics with Alumina and Rare Earth Oxides Additions
Authors: Hwang M.K. , Silva Cosme Roberto Moreira , Nono Maria do Carmo de Andrade , dos Santos Claudinei , Neto Francisco Piorino
Published: March 2009

In this work, the mechanical properties of SiC samples with (5 wt%) alumina and (5
wt%) rare earth oxides (REO) additions were investigated at room and high temperatures. The
possibility of using REO instead of pure yttria could bring cost reductions to obtain sintered SiC
ceramics. The powders were mixed, milled, sieved and hot-pressed at 1800°C in argon atmosphere.
Hardness and fracture toughness were evaluated at room temperature. The compressive creep
behavior was carried out under stress range from 150 to 300MPa and temperatures of 1300, 1350
and 1400°C. After creep tests, the surface analysis of the samples by XRD and SEM showed
indications of oxidation reactions, cavity and cracking. The possible creep mechanisms activated in
this system were diffusion, grain boundary sliding and cavitation
Study of Cutting Forces on Machinability Properties of Gray Cast Iron Using New Ceramics Cutting Tools
Authors: Souza José Vitor C. , Nono Maria do Carmo de Andrade , Oliveira Rodrigo de Matos , Ribeiro M.V. , Silva Olivério Moreira Macedo
Published: March 2009

During gray cast iron cutting, the great rate of mechanical energy from cutting forces is
converted into heat. Considerable heat is generated, principally in three areas: the shear zone, rake
face and at the clearance side of the cutting edge. Excessive heat will cause undesirable high
temperature in the tool which leads to softening of the tool and its accelerated wear and breakage.
Nowadays the advanced ceramics are widely used in cutting tools. In this paper a composition
special of Si3N4 was sintering, characterized, cut and ground to make SNGN120408 and applyed in
machining gray cast iron with hardness equal 205 HB in dry cutting conditions by using digital
controlled computer lathe. The tool performance was analysed in function of cutting forces, flank
wear, temperature and roughness. Therefore metal removing process is carried out for three
different cutting speeds (300 m/min, 600 m/min, and 800 m/min), while a cutting depth of 1 mm
and a feed rate of 0.33 mm/rev are kept constant. As a result of the experiments, the lowest main
cutting force, which depends on cutting speed, is obtained as 264 N at 600 m/min while the highest
main cutting force is recorded as 294 N at 300 m/min.
Densification and Electrical Conductivity of Mn-Doped CeO2
Authors: Santos Emilene Laurentino , Muccillo R. , Muccillo E.N.S.
Published: March 2009

The influence of Mn addition (from 1 up to 10 mol%) on densification and electrical
conductivity of CeO2 was studied in detail. Bulk specimens were prepared by the conventional
technique of mixing suitable amounts of cerium dioxide and manganese carbonate, followed by
pressing and sintering. The apparent density of sintered specimens was determined by the
immersion method and electrical characterization was carried out by impedance spectroscopy
measurements in the 300 to 550 °C range. High densification (> 95% of the theoretical density) was
obtained for small addition of Mn (1 mol%) to CeO2 sintered at 1300 °C for only 0.1 h. Electrical
conductivity changes in sintered pellets depend on the sintering procedure, but not on the
manganese content.
Study of Sintering Behavior of Ba2AlSnO5.5 Ceramic Powder Compacts as Substrate for Temperature Sensing Devices
Authors: Yadava Yogendra Prasad , Ferreira Ricardo Arthur Sanguinetti
Published: March 2009

Ceramic components are frequently used as substrates for the production of temperature
sensing devices in petroleum industries, in view of their high thermal and electrical resistance and
inertness in hostile ambient conditions. Complex cubic perovskite oxide ceramics have a great
advantage in terms of their varied physico-chemical characteristics with the substitution of
structural elements in the respective formula units. In this context, we have produced Ba2AlSnO5.5
ceramics by solid state reaction process. Structural characteristics, studied by powder x-diffraction,
reveal that Ba2AlSnO5.5 ceramic has an ordered complex cubic perovskite structure. Ba2AlSnO5;5
ceramics were sintered in the form of circular discs of 10 and 15 mm diameters and 2 mm
thickness, in the temperature 1200 to 14000C by normal sintering process. The microstrutural
characteristics were studied by scanning electron microscopy on both polished and fracture
surfaces. The SEM micrographs show homogenous surface morphology and particle size
distribution. Mechanical hardness of the sintered Ba2AlSnO5.5 ceramics were studied by Vicker´s
hardness tests. The results of these studies have been presented and discussed in this work
Technological Aspects Concerning the Production Procedures of UO2-Gd2O3 Nuclear Fuel
Authors: Durazzo Michelangelo , Riella Humberto Gracher
Published: March 2009

The direct incorporation of Gd2O3 powder into UO2 powder by dry mechanical blending
is the most attractive process for producing UO2-Gd2O3 nuclear fuel. However, previous
experimental results by our group indicated that pore formation due to the Kirkendall effect delays
densification and, consequently, diminishes the final density of this type of nuclear fuel.
Considering this mechanism as responsible for the poor sintering behavior of UO2-Gd2O3 fuel
prepared by the mechanical blending method, it was possible to propose, discuss and, in certain
cases, preliminarily test feasible adjustments in fabrication procedures that would minimize, or even
totally compensate, the negative effects of pore formation due to the Kirkendall effect. This work
presents these considerations.
Synthesis of Potassium Titanate Fibers for Friction Materials
Authors: Yoshimura H.N. , Molisani André Luiz , Fredericci Cátia , de Oliveira K.S. , Weber A.C.L. , Martins A.L.M.
Published: March 2009

Potassium hexa and octatitanate fibers have been proposed as reinforcement for friction
materials. The aim of this work was to establish a calcination route to produce these fibers, using
commercial anatase and potassium carbonate powders. These powders were dry mixed with
TiO2/K2O molar ratio, n, of 3.0, 3.5, and 4.0, and then calcined at 950, 1050, and 1150°C for 3 h.
Calcined powders were milled, washed in warm water with different pHs, and heat treated to
crystallize the fibers. The best conditions to growth long fibers were n=3.0 and 1050°C, in the twofase
field (liquid + K2Ti4O9). Controlled ion-exchange with water removed K+ ions from K2Ti4O9
fibers resulting in potassium hexa or octatitanate fibers after the second heat-treatment. Fibers with
sub-micrometer thickness (~0.6 μm) and average length of ~20 μm could be prepared.
Brazilian Bentonites for Geosynthetic Clay Liners (GCL)
Authors: Monteiro M.A.F. , Ribeiro A.P. , Machado A.T. , Toffoli S.M. , Martín-Cortés Guillermo Ruperto , Wiebeck Helio , Valenzuela-Díaz Francisco Rolando
Published: March 2009

Bentonites have been used for several purposes, due to their excellent physical, chemical,
and structural properties. The main applications of bentonites in Brazil are, among others, as
agglomerants for foundry molds, in iron ore pelletizing, as drilling mud in oil and water wells, as
wine clarifiers, in catalysis, at the chemical and pharmaceutical industries, for pollutants removal in
water treatment plants, and in cosmetics. Since the 1980’s, bentonites have been used as barriers in
landfills, thanks to the attractive characteristics of the montmorillonite, the principal clay mineral in
the smectitic clays (popularly called bentonites). The inadequate accumulation of residues in soils
and waters is identified as one of the most serious current problems. Nowadays, geosynthetic clay
liners, or GCL’s, have been used as a geo-synthetic hydraulic barrier. They are constituted by a
sodium or calcium bentonite layer encapsulated in geo-textiles or attached to geo-membranes,
which are secured together by physical or chemical methods. This paper discusses GCL’s, their
uses, the influences of the type of clay, the working principles, the related aspects to landfills
projects, and also the main Brazil’s bentonite exploitation areas.
Microstructural Evaluation of the Zirconia Plasma Sprayed Coating on Ti-6Al-4V Alloy after Creep Test
Authors: Reis Danieli A.P. , Silva Cosme Roberto Moreira , dos Santos Claudinei , de Moura Neto Carlos , Barboza M.J.R. , Neto Francisco Piorino
Published: March 2009

The titanium affinity by oxygen is one of main factors that limit the application of
their alloys as structural materials at high temperatures. The objective of this work was evaluating
the microstructure of the of the zirconia plasma sprayed coating Ti-6Al-4V alloy in creep test.
Yttria (8 wt.%) stabilized zirconia (YSZ) (Metco 204B-NS) with a CoNiCrAlY bond coat
(AMDRY 995C) was atmospherically plasma sprayed on Ti-6Al-4V substrates by Sulzer Metco.
Constant load creep tests were conducted with Ti-6Al-4V alloy in air and in nitrogen atmospheres
in uncoated samples and in air in coated samples at stress level of 56 MPa at 700°C. The
microstructural analyze show that the predominant mechanism in the test conditions was
characterized by formation and coalescence of micro cavities with shape and size varieties. The
cavities are corrugated in discontinue regions, like inclusions and points involving dislocation. The
size and shape of dimples are governed by number and distribution of nucleated micro cavities and
by stress internal level present in the material.
Research on Piezoelectric Actuator Driving Method of Creep Resistance
Authors: Fan Wei , Yu Xiao Fen , Li De Bao
Published: March 2009

The piezoelectric actuator demonstrates superior characteristics of high displacement
resolution, miniature size, high-frequency response, strong power, no generate heat etc, So it is used in
nano systems widely. But its inherent hysteresis, creep and non-linearity affect positioning accuracy
seriously. In this paper, through the investigative experiment of a large travel piezoelectric actuator
worktable’s creep characteristics, creep characteristic curve and the rules of the piezoelectric actuator
creep were found. Based on the rules of the piezoelectric actuator creep characteristics, the piezoelectric
actuator creep resistance driving method of two-level reversely applied voltage could remarkably reduce
the creep error of system, namely, applying stepped voltage reversely according to two stages. The
experiments show that the creep error of the system has been reduced from 3.80% to 0.26%, the period of
creep tends to be stable, and also has been shortened within 10 seconds. This driving method make the
quick and precise piezoelectric actuator positioning control with large displacement become possible. It
also provides further scientific method to amend and reduce the creep effect of piezoelectric actuator, and
improves the positioning accuracy of the system.
Effects of Substrate Geometry on Performance of Twin-Fluid Atomizer in Metal Powder Production
Authors: Wang Muh Ron , Yang Che Jui , Huang Jian Duen , Lin Tien Chu , Sheu Ming Shen
Published: March 2009

Uniform and spherical metal powders have been widely used in many industrial
applications. This paper investigates the control of particle size and size distribution by the
impingement of the molten spray on the substrate with different geometries. The idea is to combine
the atomization process with the classification process. Result shows that a significant reduction of
the particle size occurred when the substrate was placed in the spray jet. The mean particle size was
lowered to 8.0μm with a low transmission ratio of the spray jet in the existence of the ring type
substrate. The particle size increased from 8.78μm to 12.67μm as the transmission ratio was
increased from 13.92% to 75.80%. The reduction in particle size was due to the effect of the
blockage of the substrate on the spray. The particle size increased from 6.72μm to 6.98μm when the
disk-type substrate was placed at Z = 150mm and 200mm, respectively. The particle size of this
case was smaller than the case with ring type substrate because the transmission ratio of the disk
type substrate was lower. The percentage of small particles (i.e., V15-) were higher than 60% and the
percentages of V25-45 were 4.19% and 0.37% when the disk-type substrate was placed at Z=150mm
and Z=200mm, respectively, indicating that almost all of the particles were below 25μm under these
conditions. Hence this technique is very effective in controlling the particle size in the metal powder
production.
Macro-Micro Modeling Analysis of Melting and Re-Solidification of Thin Si Films by Excimer Laser Annealing
Authors: Chao Long Sun , Chang Chien Hung
Published: March 2009

In this work, an macro-micro model has been developed for the melting and resolidification
of thin Si films induced by excimer-laser annealing. The macro-micro model, considering the
formation of microstructures: nucleation and growth, can obtain the better results than macro-models.
Except temperature distributions, the macro-micro models can offer more information about
solidification process, such as undercooling, grain size, grain density etc. These data could help to
predict the physical properties of materials. In this study, the finite difference method is utilized to
solve the heat transfer problem. The specific heat/enthalpy method and the source term scheme are
employed to handle the absorbed and released latent heat. The algorithm that allows for nucleation is
based on classical nucleation theory. Accordingly, the model enables the prediction of grain size, as
well as the calculation of other critical responses of the a-Si film, such as undercooling. From the
computational results, it can be found that when the laser fluence is higher, the cooling rate after laser
irradiation is lower, the maximum undercooling is smaller and the grain size is larger or the grain
density is lower. The average grain sizes, obtained from the simulation results of the proposed model,
agree fairly well with those from the experimental data reported in the literature. It can also be found
that the reflectivity of the surface gives a good way to observe the phase changes and the melting
duration.
A Forging Simulation by Using the Point Collocation Method with a Boundary Layer of Finite Element
Authors: Guo Yong Ming
Published: March 2009

Point collocation methods have no mesh, no integration. While, the robustness of the
point collocation methods is an issue especially when scattered and random points are used. To
improve the robustness, some studies suggest that the positivity conditions can be important when
using the point collocation methods. For boundary points, however, the positivity conditions cannot
be satisfied, so that it is possible to get large numerical errors from the boundary points when using
the point collocation methods. The author has proposed a point collocation method with a boundary
layer of finite element. In this method, by introducing a boundary layer of finite element in
boundary domain of workpiece, unsatisfactory issue of the positivity conditions of boundary points
can be avoided, and the complicated boundary conditions can be easily imposed with the boundary
layer of finite element. A forging process is analyzed by using the point collocation method with a
boundary layer of finite element.
Evaluation of UHMWPE Component under Various Positions for UKA
Authors: Liu Chien Wei , Li Wen Lung , Yu Chen Tung , Lo Chia Chi
Published: March 2009

The development of artificial joints is now considered quite mature, and the main treatment
for osteoarthritis. However, in recent unicompartmental knee arthroplasty (UKA) clinical
follow-ups, complications due to wear of polyethylene (PE) tibial components still exist. Therefore,
this study focused on the possibility of avoiding and minimizing damage to the PE tibial component.
Currently, the most common problem in the application of UKA is the malresection of the tibial
plateau, often resulting in malpositioning of the tibial implant. This positioning problem may be the
main reason for advanced wear and dislocation of a PE tibial component. In this study, finite element
analysis (FEA) was used to study the stress change of malpositioned PE tibial components in order to
better understand the damaging mechanism on PE tibial components. It was found that anatomically
designed unicompartmental knee prostheses (UKP) allowed more positioning error in varus tilt than
symmetrically designed ones. And both should avoid any positional error greater than 10° valgus tilt.
Otherwise, increased wear of PE tibial components would result in shortened lifetime of the artificial
joint.
Development of a Laboratory-Scale Pilot for Studying Corrosion on MSWI Heat Exchangers
Authors: Lebel Florimonde , Rapin Christophe , Mareche Jean François , Podor Renaud , Chaucherie Xavier , Guernion Pierre Yves , Brossard Jean Michel
Published: March 2009

The efficiency of Waste-to-Energy (W-t-E) boilers is affected by fireside corrosion of the
heat exchangers that involve unexpected shutdown of facilities for repairs and limit the increase of
steam conditions used to produce electricity. The parameters governing fireside corrosion are
various and mechanisms are very complex, nevertheless, they are relatively well documented in the
literature.
In this paper, a laboratory-scale corrosion pilot, which reproduces MSWI boilers conditions, is
described. The specificity of our approach includes simultaneous simulation of the temperature
gradient at flue-gas/tube interface, the velocity of flue-gas and ashes. Corrosion rates obtained on
Tu37C carbon steel at a metal temperature equal to 400°C and a flue gas temperatures of 650°C and
850°C (1100 ppm HCl, 110 ppm SO2 and synthetic ashes free of heavy metals) are respectively
around 1.6 2m/hour and 5.6 2m/hour. Preferential metal loss, attributed to erosion-corrosion
phenomena, is also observed at low flue-gas temperature (T=650°C) on the face exposed at 90° to
the flue-gas.
The analysis of corrosion scales demonstrates the reproducibility of results and the reliability of
corrosion mechanisms determined from experiments, with degradation observed similar to
superheater tubes from EfW facilities. Thus, the corrosion pilot developed can be used as an
accurate simulator of the environment encountered in MSWI.
Imaging by Photoelectrochemical Techniques of Laves-Phases γ Zr(Fe,Cr)2  Thermally Oxidized on Zircaloy-4
Authors: Atmani F. , Wouters Yves , Galerie Alain , Petit Jean Pierre , Dali Yacoub , Tupin Marc , Bossis Philippe
Published: March 2009

The oxidation of γ-Zr(Fe,Cr)2 intermetallic particles during the thermal exposition of
Zircaloy-4 at 470°C in oxygen was investigated with PhotoElectroChemical techniques (PEC). Via
the measurement of bandgap, haematite Fe2O3 (2.2 eV), rhomboedric solid solution (FexCr1-x)2O3
(2.6 eV) and chromia Cr2O3 (3.0 eV) phases were identified as components of oxidised particles.
Evolution of size, lateral distribution and density of these particles was studied in function of
zirconia scale thickness. During the first stage of oxidation, the density of oxidised particles
increased with thickness but decreased during a second stage, highlighting in an innovative way the
phenomenon of haematite and chromia dissolution in the zirconia matrix. It is concluded that PEC
techniques represent a sensitive and powerful way to locally analyse the various semiconductor
phases in an oxide scale at the micron scale.
Metal Dusting Behaviour of Alloy800H in Laboratory Carbonaceous Environments under High Pressure
Authors: Nishiyama Yoshitaka , Kitamura Kazuyuki , Otsuka Nobuo
Published: March 2009

Metal dusting behaviour of alloy800H was investigated in a laboratory-pressurized reactor
where CO-H2-CO2-H2O gas mixtures flowed continuously, simulating the gas environments in
actual syngas production plant. Four test conditions, having a variety of gas pressures and H2O
contents, were conducted for a long rod specimen that was imposed thermal gradient of 777°C to
454°C in a longitudinal direction. After an exposure of 100h at high pressure, metal dusting has
initiated with a bell-shape distribution on the test specimens at temperatures between 600°C and
700°C. Gas pressure has accelerated metal dusting even if the gas atmospheres had the same gas
composition. On the contrary, metal dusting has been alleviated with increasing the H2O content in
the test gas. Oxide scale characterisations were analyzed by using Raman spectroscopy and XPS at
the test specimen surfaces exposed at different temperature. The ratio of a protective Cr2O3 scale to
spinel oxides such as FeCr2O4 and MnCr2O4 has increased with increasing the exposure temperature,
with reducing the gas pressure, and with lowering the H2O content. These behaviours have been
interpreted from thermodynamic indices: carbon activity ac and the oxide scale integrity related to
oxygen potential Po2 as a function of temperature.