bluuebunny/crossref_metadata_2025 huggingface dataset:
Sintering of High K LTCC Compatible Dielectrics
Authors: Duguey Sonia , Lebourgeois Richard , Heintz Jean Marc
Published: March 2009

This study deals with the co-sintering of copper oxide added ANT with alumina tapes
and silver ink. AgNb1/2Ta1/2O3 (refered ANT 22) was synthesized using niobium oxide with fine
and large grain size to examine the effect of the granulometry on the tape casting. The resulting
multilayers were co-fired between 850 and 900°C. Phase identification was investigated by XRD.
Energy Dispersive Spectroscopy was performed to study the interdiffusion between the layers.
Permittivity and dielectric losses were measured at 50 kHz for both tape cast samples and bullk
material. No interdiffusion was observed between ANT/silver and ANT/alumina and this is a very
promising result for LTCC applications.
Development of the High Performance Thermoelectric Modules for High Temperature Heat Sources
Authors: Jinushi Takahiro , Okahara Masahiro , Ishijima Zenzo , Shikata Hideo , Kambe Mitsuru
Published: March 2009

In recent years, power generating systems using thermoelectric elements have become attractive as an effective method of using industrial waste heat, at a temperature of around 773K, to produce energy. However, in order to develop a module usable under such a high temperature, certain concerns have to be overcome, e.g. thermal stress, diffusion of the connecting interfaces, etc. In this research, using an FeSi2 with diffusion barrier layers and a SiGe element produced by a powder metallurgy process, the module structure and installation method were optimized for application in PM sintering furnaces. As a result, from a viewpoint of heat stress at high temperatures and contact thermal resistance, it is confirmed that the optimal structure is the skeleton structure using Cu substrate on the cooling side, which has excellent heat conductivity and the optimal installation method is to adopt a carbon sheet and a mica sheet to the high temperature side, where Si grease is applied to the low temperature side, under pressurized condition. The power of the developed modules indicated 0.5W in an FeSi2 module and 3.8 W with a SiGe module at 827K, respectively. Moreover, neither breakage nor deterioration were observed after 30 heat cycles test simulating sintering furnace.
Thermoelectric Properties of Ni-Doped CoSb3 Prepared by Encapsulated Induction Melting and Hot Pressing
Authors: Kim Mi Jung , Lee Jung Il , Ur Soon Chul , Kim Il Ho
Published: March 2009

Ni-doped CoSb3 was prepared by the encapsulated induction melting and hot pressing, and its doping effects on the thermoelectric properties were investigated. Single phase δ-CoSb3 was successfully obtained by the subsequent heat treatment at 773K for 24 hours. Nickel atoms acted as electron donors by substituting cobalt atoms. Thermoelectric properties were remarkably improved by the appropriate doping.
Biocompatibility and Mechanical Performance of Ni-Ti
Authors: Kim J. , Choi Y.C. , Kim Hyoung Seop , Hong Sun Ig
Published: March 2009

Biomimetic apatite deposition behaviors and mechanical performance for as-rolled and
annealed Ni-Ti plates were investigated. Apatite nucleation and growth on Ni-Ti in SBF (simulated
body fluid) was not appreciably influenced by heat treatment. But, the apatite deposition rate
increased slightly by NaOH surface treatment. The nodular apatite on the deposited layer is favored
on a macro-scale since the surface energy of polycrystalline apatite particles can be reduced by
forming nodules. The weight gain after apatite deposition for Ni-Ti (0.004 g/cm2) after 10 days
were found to be smaller that that of NaOH treated Ti-6Al-4V, but it was comparable to that of non-
NaOH-treated Ti-6Al-4V (0.004 g/cm2). The stress-strain responses of annealed Ni-Ti displayed the
pseudoelastic behavior associated with stress-induced martensite formation with the transition stress
for the martensite formation equal to 320 MPa. On the other hand the cold worked Ni-Ti displayed
no appreciable pseudoelastic region and the yield stress was ~500MPa. A good biomimetic apatite
formation and excellent mechanical performance of Ni-Ti suggests that Ni-Ti can be an excellent
candidate material for orthopedic implants.
Prediction of Packing Density of Milled Powder Based on Packing Simulation and Particle Shape Analysis
Authors: Amano Yuto , Itoh Takashi , Terao Hoshiaki , Kanetake Naoyuki
Published: March 2009

For precise property control of sintered products, it is important to know the powder
characteristics, especially the packing density of the powder. In a previous work, we developed a
packing simulation program that could make a packed bed of spherical particles having particle size
distribution. In order to predict the packing density of the actual powder that consisted of nonspherical
particles, we combined the packing simulation with a particle shape analysis. We
investigated the influence of the particle size distribution of the powder on the packing density by
executing the packing simulation based on particle size distributions of the actual milled chromium
powders. In addition, the influence of the particle shape of the actual powder on the packing density
was quantitatively analyzed. A prediction of the packing density of the milled powder was
attempted with an analytical expression between the particle shape of the powder and the packing
simulation. The predicted packing densities were in good agreement with the actual data.
Thermal Stability of Amorphous Ti- Cu- Ni- Sn Prepared by Mechanical Alloying
Authors: Oanh N.T.H. , Choi Pyuck Pa , Kim Ji Soon , Kwon Dae Hwan , Kwon Young Soon
Published: March 2009

Ti-Cu-Ni-Sn quaternary amorphous alloys of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and
Ti50Cu23Ni20Sn7 composition were prepared by mechanical alloying in a planetary high-energy ballmill
(AGO-2). The amorphization of all three alloys was found to set in after milling at 300rpm speed
for 2h. A complete amorphization was observed for Ti50Cu32Ni15Sn3 and Ti50Cu25Ni20Sn5 after 30h and
20h of milling, respectively. Differential scanning calorimetry analyses revealed that the thermal
stability increased in the order of Ti50Cu32Ni15Sn3, Ti50Cu25Ni20Sn5, and Ti50Cu23Ni20Sn7.
Densification and Conolidation of Powders by Equal Channel Angular Pressing
Authors: Yoon Seung Chae , Hong Sun Ig , Hong Soon Hyung , Kim Hyoung Seop
Published: March 2009

In this study, bottom-up type powder processing and top-down type SPD (severe plastic
deformation) approaches were combined in order to achieve both full density and grain refinement of
metallic powders with least grain growth, which is considered as a bottle neck of the bottom-up
method that uses the conventional powder metallurgy of compaction and sintering. ECAP (Equal
channel angular pressing), one of the most promising method in SPD, was used for the powder
consolidation. In the ECAP process of not only solid but also powder metals, it is important to get a
good understanding of the density as well as internal stress, strain and strain rate distribution. We
investigated the consolidation, plastic deformation and microstructure evolution behavior of the
metallic powders during ECAP using an experimental method. It was found that high mechanical
strength could be achieved effectively due to the well bonded powder contact surface during ECAP
process of gas atomized Al-Si powders. The experimental results show that SPD processing of
powders is a viable method to achieve both fully density and nanostructured materials.
Effect of Polymer Compatibility on the Binder Migration during Spray Drying and Compaction Behavior
Authors: Kim Ungsoo , Kim Duck Kyeom , Carty William , Pee Jae Hwan , Choi Eui Seok
Published: March 2009

Granular feedstock for dry pressing is prepared by spray drying oxide powders with polymeric additives. The interactions between polymeric additives in suspension or during drying are usually considered negligible. However, recent studies demonstrate that interactions between polymers usually do occur and can adversely affect product performance. Flory-Huggins calculations predict phase separation of Na-PMAA and Na-PAA with PVA and homogeneous mixing of Na-silicate with PVA. These predictions were confirmed by the light scattering studies on polymer solutions and morphology studies on dried polymer solutions. This reveals that the interaction between polymers can lead to either a homogeneous or phase-separated solution, depending on the functional groups and chain length of polymers. PVA binder in spray-dried granules is stained and its location within the spray dried granule is observed verifying the effect of other polymers on binder migration and case-hardening of spray dried granules. The results indicate polymeric additives that prevent binder migration, potentially eliminating case-hardening in spray dried granules and the subsequent problems observed during compaction.
Numerical Simulation of Cold Compaction of 3D Granular Packings
Authors: Chen Yuan , Imbault Didier , Dorémus Pierre
Published: March 2009

During cold compaction processes loose powder is pressed under tooling action in order
to produce complex shaped engineering components. Here, the analysis of the plastic deformation
of granular packings is of fundamental importance to the development of computer simulation
models for industrial forming processes. Powders can be idealized by packing discrete particles,
where each particle is a sphere meshed with finite elements. During pressing, particles are deformed
by elastic-plastic hardening where friction is present at each contact. The pressing of an isolated
particle followed by a body centered cubic packing was compared with numerical prediction and
experimental data. The analysis was focused on the interaction between particles and the global
response expressed in force-displacement curve during compaction. The accuracy of the numerical
models was also analyzed for high relative densities up to 0.95.
Development of Dental Scaler Tip Mold with Powder Injection Molding Process
Authors: Hwang Chul Jin , Ko Y.B. , Park Hyung Pil , Chung S.T. , Rhee Byung Ohk
Published: March 2009

With the capability of net shaping for complex 3D geometry, powder injection molding
(PIM) is widely used for automotive parts, electronics and medical industry. In this study, an
ultrasonic dental scaler tip produced by machining process was redesigned for the PIM process. An
injection mold was designed and machined to produce the dental scaler tip by the PIM process. The
mold design was aided by CAE analysis. A PIM feedstock was made of SUS316L powder and a
wax based binder. The filling balance in the mold was checked by a short shot test with LDPE and
the PIM feedstock. Production capability of the PIM process for the dental scaler tip was examined
with the mold. Although there were minor problems such as a discoloration around the gate and a
flashing at the air vent, the PIM process turned out to be an excellent substitute for machining
process to manufacture the ultrasonic dental scaler tip.
Three-Dimensional Printing of Shape Memory Alloys
Authors: Carreño-Morelli Efrain , Martinerie Sebastien , Bidaux J. Eric
Published: March 2009

A novel variant of the three-dimensional printing technique has been developed and used
to manufacture NiTi parts. Instead of metal powder the process uses granules, which consist of a
mixture of metal powder and organic binder. These granules are spread on a working table. Then a
solvent is dispensed with a printer head to consolidate a selected area of the granule bed and the
table is moved down. The "solvent on granule" printing process is repeated until a threedimensional
green body is obtained. The green part is finally debinded and sintered to obtain a
dense and fully metallic part. NiTi parts have been successfully produced by this technique with
densities of about 95% of the theoretical density. Detailed information on the microstructure has
been obtained by X ray diffraction. Sintered parts exhibit shape memory effect, which has been
measured during thermal cycling under tensile stress.
Comprehensive Wear Study on Powder Metallurgical Steels for the Plastics Industry, Especially Injection Moulding Machines
Authors: Gornik Christian , Perko Jochen
Published: March 2009

M390 microclean® of Böhler Edelstahl is a powder metallurgical plastic mould steel with
a high level of corrosion and wear resistance and therefore often used in the plastics processing
industry. But as a consequence of rapidly advancing developments in the plastics processing
industry the required level of wear resistance of tool steels in this field is constantly rising. For that
reason a new PM tool steel with higher hardness values and an increased amount of primary
carbides has been developed to improve the resistance against abrasive and adhesive wear. The
wear resistance of both steels against adhesive situations for components of the plastification unit of
injection moulding machines has been tested with a novel method. In case of processing polyolefins
with an injection moulding machine it was found that there is adhesive wear between the check-ring
and the flights of the screw tip of the non-return valve under certain circumstances. The temperature
in that region was measured with an infrared temperature sensor. The existence of significant peaks
of that signal was used as an indicator for an adhesive wear situation.
Hybrid Atomization Method for Manufacturing Fine Spherical Metal Powder
Authors: Minagawa Kazumi , Kakisawa Hideki , Halada Kohmei
Published: March 2009

Hybrid atomization is a new atomization technique that combines gas atomization with centrifugal atomization. This process can produce fine, spherical powders economically with a mean size of about 10 μm diameter and a tight size distribution. Experiments on the process were carried out using a Sn-9 mass% Zn alloy to investigate the influence of processing parameters on powder characteristics in hybrid atomization. The primary atomization mechanism under normal hybrid atomization conditions is predicted to be direct drop formation mode.
Influence of Binders on the Structure and Properties of High Speed-Steel HS6-5-2 Type Fabricated Using Pressureless Forming and PIM Methods
Authors: Matula G. , Dobrzański Leszek Adam , Herranz Gemma , Várez A. , Levenfeld B. , Torralba José M.
Published: March 2009

Based on the comparison of structures and properties of the HS6-5-2 high speed steels
made with the powder injection moulding method, pressureless forming, compacting and sintering,
and commercial steels made with the ASEA-STORA method, fine carbides spread evenly in the
steel matrix were found in the structure of all tested high-speed steels in the sintered state. The use
of a nitrogen atmosphere in the sintering process, causes the formation of fine, spherical MX type
carbonitrides, stable in high sintering and austenitizing temperatures. The steels made with the
pressureless forming method are characteristic of the lowest sintering temperature and the highest
density, resulting from the high carbon concentration coming from the binding agent degradation.
Moreover, the higher carbon concentration causes an increase in the retained austenite portion and a
lower hardness after quenching and tempering. The heat-treated injection moulded steel attains
hardness comparable to the commercial ASP23 type one, demonstrating the well-founded reasons
for using the powder-injection moulding method for manufacturing the high-speed steel. The
powder-injection moulding makes manufacturing tools possible with their final shape, i.e., leaving
out the plastic forming and machining which is necessary for instance in case of the ASP 23 type
steel. Furthermore, the degradation and sintering process time of the injection moulded steels is
approximately 10h shorter than for steels made with pressureless moulding, which is due to the use
of a two-component binding agent.
Stable and Unstable Crack Growth in Chromium Pre-Alloyed Steel
Authors: Gerosa Riccardo , Rivolta Barbara , Tavasci Adriano , Silva Giuseppe , Bergmark Anders
Published: March 2009

Powder metallurgy processing of steels typically results in a material characterized by residual porosity, whose dimension and morphology, together with the microstructure, strongly affect the fatigue crack growth behaviour of the material. Prismatic specimens were pressed at 7.0 g/cm3 density from Astaloy CrM powder and sintered in different conditions, varying the sintering temperature and the cooling rate after sintering. Optical observations allowed to evaluate the dimensions and the morphology of the porosity and the microstructural characteristics for all the investigated conditions. Fatigue tests were performed at R-ratio equal to 0.1 to investigate the threshold zone and to calculate the Paris law coefficients. All the tests were carried out according with the compliance method, and the crack length has been evaluated during whole the test. Moreover KIc tests were performed in order to complete the investigation. Both on fatigue and KIc samples a fractographic analysis was carried out to investigate the crack path and the fracture surface features. The results show that the Paris law crack growth exponent is around 6.0 for 1120°C sintered and around 4.7 for 1250°C sintered materials. The same dependence to process parameters is not found for KIth. Values close to 6 MPa√m are here found for all variants.
Study of Elastic Moduli of Sintered Low Alloy Steels by Acoustic Pulse Method
Authors: Hirose Norimitsu , Oouchi Kazuya , Fujiki Akira , Asami Junichi
Published: March 2009

The influence of porosity (P) on Young’s modulus (E) and Poisson’s ratio (υ) of sintered
steels produced from four types of steel powders were investigated. The values of E and υ depends
mainly on the value of P, and those were a little affected by alloying elements. The relationship
between compacting pressure (CP) and P and the relationships between E, υ, and P were described
as following equations:
P = P1 + P2 exp(- CP / P3), E = E0 (1 - kEP)2, and υ = (υ0 - υsub)(1 - kυP)2 + υsub, where subscript 0
means P = 0, and P1 - 3, kE, kυ and υsub were empirical constants. It was clarified that if powder and
sintering temperature is defined, the elastic moduli of sintered steel can be calculated as a function
of compacting pressure.
Hydrothermal Synthesis of Rod-Like Copper Oxide Crystals
Authors: Pee Jae Hwan , Lee Dong Wook , Kim Ungsoo , Choi Eui Seok
Published: March 2009

A hyrdrothermal reaction process has been developed to prepare rod-like crystals of
copper oxide using copper nitrate trihydrate as a function of synthesis temperature, stirring speed
and solution pH value. The properties of the fabricated crystals were studied using scanning
electron microscopy, X-ray diffraction and particle size analysis. The morphology of the
synthesized CuO was dependent on both the pH value of the solution and the morphology of the
seed materials. Synthesized particles have regular morphologies and a uniform size distribution.
Aluminium and Aluminium Alloy Powders for P/M Applications
Authors: Cook R. , Chang I.T.H. , Falticeanu C. Lucien
Published: March 2009

P/M aluminium components are attracting interest in an increasing variety of industries
due to the possibilities for weight saving in engineering parts. There are many processes for
manufacturing from powder feedstocks that are either in production, becoming commercialised or
still undergoing development. The nature of these processes and the required properties of the end
products mean that powders of different particle size, shape, composition and microstructure must
be produced.
The requirements of various processes requiring aluminium and aluminium alloy powders for metal
matrix composites, laser sintering, powder forging and metal injection moulding are discussed in
relation to powder particle size and structure. The key requirement of the powder manufacturer is to
supply cost effective materials for these different processes. This may require compromises to be
made by the supplier and consumer while the techniques evolve from development to large scale
production.
Gas Chromatographic Analysis of Degassing of Aluminum and Aluminum Alloy Powders
Authors: Watanabe Ryuzo , Choi Duk Sun , Kawasaki Akira
Published: March 2009

Gas release behavior from aluminum and Al 7075 alloy powders during heating in argon was investigated by in-situ gas chromatography. Water vapor, hydrogen, carbon mono-oxide were detected as individual evolution spectra against heating temperature and time. The mechanisms of water and hydrogen evolutions were studied in detail for the determination of effective degassing condition. The adsorbed water and aluminum hydrate on the particle surfaces were considered to be the sources for the released water. Hydrogen peaks were formed from released gases through the reaction of aluminum and magnesium with adsorbed and hydrated water, and from liberated hydrogen that would have been excessively occluded during atomization. For the alloy powder magnesium was found to lower the hydrogen evolution temperature to enhance overall hydrogen release.
Carbon-Nanofiber Reinforced Cu Composites Prepared by Powder Metallurgy for Thermal Management of Electronic Devices
Authors: Weidmueller Hendrik , Weissgaerber Thomas , Hutsch Thomas , Huenert R. , Schmitt T. , Mauthner K. , Schulz-Harder J.
Published: March 2009

Electronic packaging involves interconnecting, powering, protecting, and cooling of semiconductor circuits for the use in a variety of microelectronic applications. For microelectronic circuits, the main type of failure is thermal fatigue, owing to the different thermal expansion coefficients of semiconductor chips and packaging materials. Therefore, the search for matched coefficients of thermal expansion (CTE) of packaging materials in combination with a high thermal conductivity is the main task for developments of heat sink materials electronics, and good mechanical properties are also required. The aim of this work is to develop copper matrix composites reinforced with carbon nanofibers. The advantages of carbon nanofibers, especially the good thermal conductivity, are utlized to obtain a composite material having a thermal conductivity higher than 400W/mK. The main challenge is to obtain a homogeneous dispersion of carbon nanofibers in copper. In this paper, a technology for obtaining a homogeneous mixture of copper and nanofibers will be presented and the microstructure and properties of consolidated samples will be discussed. In order to improve the bonding strength between copper and nanofibers, different alloying elements were added. The microstructure and the properties will be presented and the influence of interface modification will be discussed.
Fabrication of Graded Porous Structure with Pore Size Distribution by SPS Process
Authors: Suk Myung Jin , Seo Won Sik , Kwon Young Soon
Published: March 2009

Feasibility of producing porous gradient structure by spark plasma sintering (SPS) process was examined. Adequate combination of porosity gradient and pore size distribution could be obtained by appropriately controlling the SPS parameter such as sintering temperature, sintering time, applied pressure, and stopper length. For the longitudinal porous gradient structure, pure W sample was prepared by specially shaped graphite mold. Stainless steel powder was employed for the radially layered porous structure with different pore size. The graded porous structure could be applied for the fabrication of W-Cu FGM by Cu-infiltration and high temperature filter with high filtration efficiency.
Micro-Porous Nickel Produced by Powder Metallurgy
Authors: Yamada Yasuo , Li Yun Cang , Banno Takumi , Xie Zhen Kai , Wen Cui E
Published: March 2009

Micro-porous nickel (Ni) with an open cell structure was fabricated by a special powder
metallurgical process, which includes the adding of a space-holding material. The average pore size
of the micro-porous Ni samples approximated 30 μm and 150 μm, and the porosity ranged from 60 %
to 80 %. The porous characteristics of the Ni samples were observed using scanning electron
microscopy (SEM) and the mechanical properties were evaluated using compressive tests. For
comparison, porous Ni samples with a macro-porous structure prepared by both powder metallurgy
(pore size 800 μm) and the traditional chemical vapour deposition (CVD) method (pore size 1300
μm) were also presented. Results indicated that the porous Ni samples with a micro-porous structure
exhibited different deformation behaviour and dramatically increased mechanical properties,
compared to those of the macro-porous Ni samples.
Comparison of Measured Phase Volumes with Calculated ones Created by TTT-CCT Diagram Transformation
Authors: Dudás Zoltán
Published: March 2009

Knowledge of the TTT (Time-Temperature-Transformation) or CCT (Continuous-
Cooling-Transformation) diagrams of steels is an important factor in the thermo-mechanical
processing of steels. Much experimental work has been undertaken to determine such
diagrams. Significant works have been written which can calculate TTT and CCT diagrams
for steels. The aim of the present work is to show the developed model that can provide
accurate enough TTT and CCT diagrams for steel 42 CrMo4 (where the austenitisation
temperature was 1050°C). The calculated results are compared by the experimental results.
The developed TTT phase transformation diagrams based on FEM-based phase elements and the
star-like cooling simulation make it possible to create virtual CCT diagram data.
Intercritical Interrupted Jominy Test
Authors: Réger Mihály , Verő Balázs , Csepeli Zsolt , Pinke Péter
Published: March 2009

The final microstructure of DP and TRIP assisted steels can evolve after hot working
(hot rolling) or during post heat treatment process. In the formation of the final structure a number
of different technological parameters have important role, e.g. finishing temperature of rolling,
cooling rates, temperature of intercritical annealing, etc. As a result of the individual factors and
their combinations a lot of production technology routes are feasible. The effect of the different
combinations of these technological parameters on the microstructure can be mapped by a special
Jominy end-quench test (so called intercritical Jominy end-quench test) described in this paper.
Unlike the traditional Jominy test, in this case there is a partial austenizing between A1 and A3
temperatures which results in a given amount of ferrite in the microstructure before quenching. The
amount of ferrite depends on the temperature. In some cases the quenching process was interrupted
for a given period of time in order to model the cooling process on the run-out table. During cooling
each point of the Jominy specimen has a different cooling rate, so the effect of cooling rate on the
microstructure can be evaluated along the length of the specimen.
Functionalization of Multi-Walled Carbon Nanotubes
Authors: Gergely A. , Telegdi J. , Kálmán Erika
Published: March 2009

In order to alter the physical/chemical characteristics of multi-walled carbon nanotubes (MWNTs)
we modified them by different organic reactions (Diels-Alder and Sand-Meyer reaction, oxidation)
and their d properties were characterized by thermogravimetry/mass spectrometry, photoelectron
spealterectroscopy, and nuclear magnetic resonance spectroscopy, as well as by dispersion. The
results proved that, depending on the groups built in the MWNTs, the modified carbon nanotubes
are more dispersible either in polar or apolar solvents and the suspensions are stable for long time.
The presence of the substituents in the MWNTs was proved by methods listed above, e.g. high
concentration of sulfur was detected when SO3H groups were inserted onto the MWNTs. The
enhanced thermal stability of the modified carbon nanotubes allows their further application.
Effect of Divalent Cations in Langmuir-Blodgett Films on the Protection of Copper against Corrosion
Authors: Al-Taher F. , Telegdi J. , Kálmán Erika
Published: March 2009

Langmuir-Blodgett films (LB) of hydroxamic amphiphiles were used as coating barriers on metal surface against corrosion. Two long-chain hydroxamic acids [CH3(CH2)16CONHOH] monolayers in the presence of some divalent cations (Ca2+, Mg2+, and Cu2+) have been studied at different pH of the subphase. The monolayer was characterized by surface pressure-area isotherms and visualized by Brewster angle microscope (BAM). Compact Langmuir layers were deposited on copper surface, where the modified surfaces were characterized by contact angle measurement as well as by electrochemical techniques. The morphology of LB coated copper surface was visualized by atomic force microscopy (AFM). The coated copper surfaces were tested in corrosive media at acidic and neutral pH. The results show that the multi-molecular LB films of hydroxamic acid salts form good barriers against copper corrosion. The comparison of these results with copper coated by LB layers without divalent cations shows that the presence of divalent cations in the subphase increases the copper corrosion inhibition. The octadecanoyl hydroxamic acid (C18N) results in better and more stable monolayer with cations in the subphase.
Mechanical Properties of Porous Titanium Compacts Reinforced by UHMWPE
Authors: Nomura Naoyuki , Baba Y. , Kawamura A. , Fujinuma S. , Chiba Akihiko , Masahashi Naoya , Hanada Shuji
Published: March 2009

Porous Ti compacts reinforced by ultra-high molecular weight polyethylene (UHMWPE)
were fabricated and their mechanical properties were evaluated. Ti powder atomized by plasma
rotating electrode process (PREP) was sintered at temperatures ranging from 1473 K to 1673 K for
7.2 ks in a vacuum. The porous Ti compacts contain the porosity of about 40%, irrespective of the
sintering temperature. Porous Ti/UHMWPE composites were successfully fabricated by compressing
UHMWPE powder into the porous Ti compacts. The compacts exhibit open pore structure and
enables the penetration of UHMWPE into pores in the compacts. Young’s modulus of the composites
is higher than that of the porous Ti compacts. The increment in Young’s modulus is not simply
explained by the rule of mixture because Young’s modulus of the UHMWPE is approximately 1.3
GPa. Three-point bending strength of the composites is improved, presumably due to the local stress
relief by UHMWPE in the vicinity of neck in the composites.
An Experimental Study on the Frictional Property and Long-Term Performance of GT/HDPE Composites
Authors: Seo Jung Min , Jeon Han Yong , Hwang Beong Bok , Lee Y.H. , Koo H.S.
Published: March 2009

This paper is concerned with the long-term performance of geo-textile (GT) composites in
terms of creep deformation and frictional properties. Composites of PVA GT and HDPE GM were
made to investigate the advanced properties of long-term performance related to waste landfill
applications. The same experiments were also performed for typical polypropylene and polyester GT
and compared to PVA GT/HDPE GM composites. The main purpose of this study is to develop high
performance GT composites with GM by using PVA GT which is capable of improving frictional
property and thus enhances long-term performance of GT composites. In the present experiments, GT
composites of PVA GT/HDPE GM, PVA GT of 600, 1000, 1500, 2000g/m2 and HDPE GM were
prepared in thermal bonding process. Polyester and polypropylene GT were also made in needle
punching process. The creep deformation of GT composites was measured and evaluated in
accordance with ASTM D5262. Frictional characteristics of GT composites tested in this study were
conducted with compact direct shear apparatus in accordance with ASTM D5321. It was concluded
from the present experimental study that friction coefficient of GT composites is relatively large
compared with those of polyester and polypropylene non-woven GT as long as the friction media has
similar size to the particles of domestic standard earth. In the event that 20% of the maximum tensile
strength was added to polypropylene and polyester non-woven geo-textiles, creep deformation
reached to 10% or higher, making it even impossible to find reduction factor.
Local Approach to Thermally-Sprayed Coating/Substrate Adhesion through LASAT (Laser Shock Adhesion Test)
Authors: Barradas Sophie , Jeandin Michel , Molins Régine , Borit F. , Berthe L. , Bolis C. , Boustie M. , Arrigoni M. , Ducos M.
Published: March 2009

Three interface factors may influence thermally-sprayed coatings adhesion: interface morphology (as usual), thermal and chemical features. It was shown that these three aspects of adhesion mechanisms are shown to be dependent and very local. It is especially true for cold spray which is one of the most promising spray processes. As this spraying technique is based on rapid deformation, cold spray coating/substrate interfaces show local morphological, thermal and chemical features, in a way that none of them can be neglected. LASAT is particularly suitable for testing these coatings because it can be applied to small areas (~1 mm²). From this, it has the outstanding advantage to be sensitive to fine-scaled phenomena responsible for coating adhesion.
Elecrochemical Performance of LiNi1/3Co1/3Mn1/3O2 with Al2O3 Nano-Particle Coating
Authors: Kim Hyun Soo , Kim Young Sik , Kim Seong Il , Martin Steve W.
Published: March 2009

Al2O3 nano-particles were coated on the surface of LiNi1/3Co1/3Mn1/3O2
powder using a sol-gel method. The as-prepared Al2O3 nano-particle was identified to
the cubic structure of Al2O3. The average size of the isolated Al2O3 nano-particles after
heat treatments was calculated to be ~ 4 nm. The XRD showed that the structure of
LiNi1/3Co1/3Mn1/3O2 was not affected by the Al2O3 coating. At 3 wt.% Al2O3 coatings
on LiNi1/3Co1/3Mn1/3O2, the cyclic-life performance and rate capability were improved.
However, heavier coatings (5 wt.%) on LiNi1/3Co1/3Mn1/3O2 dramatically decreased the
discharge capacity and rate capability.
Effect of Laser Surface Treatment on Microstructure and Properties of MRI 230D Mg Alloy
Authors: Mondal A.K. , Kumar Subodh , Blawert Carsten , Dahotre Narendra B.
Published: March 2009

A creep resistant Mg alloy MRI 230D was subjected to laser surface treatment using
Nd:YAG laser equipped with a fiber optics beam delivery system in argon atmosphere. The laser
surface treatment produced a fine dendritic microstructure and this treatment was beneficial for the
corrosion and wear resistance of the alloy. Long-term linear polarisation resistance and
Electrochemical Impedance Spectroscopy measurements confirmed that the polarisation resistance
values of laser treated material were twice as high as that for the untreated material. This improved
behaviour was due to the finer and more homogenous microstructure of the laser treated surface.
The laser treatment also increased surface hardness two times and reduced the wear rate by 25% due
to grain refinement and solid solution strengthening.
Cutting Properties of PVD and CVD Coated A2lO 3 + TiC Tool Ceramic
Authors: Sokovic Mirko , Dobrzański Leszek Adam , Kopač Janez , Kosec Ladislav
Published: March 2009

The paper presents investigation results of tribological and cutting properties of the
coatings deposited with the PVD and CVD techniques on cutting inserts made from the Al2O3 +
TiC tool ceramics. Tests were carried out on the inserts made from ceramics, uncoated and PVD or
CVD-coated with gradient, mono-, multilayer and multicomponent hard wear resistant coatings
composed of TiN, TiCN, TiAlN, TiAlSiN and Al2O3 layers. Substrate hardness tests and micro
hardness tests of the deposited coatings were made on the ultra-micro-hardness tester. It was
demonstrated, basing on the technological cutting tests of grey cast iron (260 HB), that putting
down onto the tool ceramics the thin anti-wear PVD and CVD coatings increases their abrasion
wear resistance, which has a direct effect on extending tool life of the cutting edge.
Numerical Simulation of Thermal History in a Novel Spray Forming Process
Authors: Liu Yun Zhong , Li Yuan Yuan
Published: March 2009

A novel spray forming process was developed to produce large billets, wide plates or
thick tubes with excellent microstructures and high cooling rates. Its uniqueness lies in a
combination of the wide-range reciprocating movement and the swing scan of a gas atomizer, and
the externally forced cooling of substrate during this spray deposition procedure. Its basic concept is
that both good sticking and rapid solidification can be achieved if droplets with high liquid fractions
impact a cold substrate, spread fully and then deposit on the surface. In order to control and
optimize this new process, the thermal histories of droplets and deposits for spray forming of
aluminum alloy billets were simulated with a set of new numerical models. Through shortening
spray distance and raising melt superheat properly, the liquid fraction of droplets before deposition
will increase and their spread on the deposit surface can improve for good sticking. Simulation
results show that the optimal liquid fraction of droplets for deposition is about 0.2 higher than that
in the conventional Osprey process. Its optimum spray distance is about 0.25m, which is nearly half
as that in the Osprey process. In addition, this new process increases the mushy layer area and the
specific surface area of heat extraction during deposition. Together with the forced cooling of
substrate, it results in higher cooling rates. A high-quality large billet can be obtained by controlling
the atomizer movement, the droplet liquid fraction and the deposit surface temperature properly in
this new process.
Novel High Temperature-Oxidation-Resistant Nanocomposites Developed by Nanocomposite Electrodeposition
Authors: Peng X. , Yang X. , Zhang Y. , Zhou Y. , Wang F.
Published: March 2009

Formation of a protective scale such as chromia or alumina is a prerequisite for an excellent
oxidation performance of high-temperature materials. Based on this principle, a novel concept of designing
chromia- or alumina-forming nanocomposites by means of nanocomposite electrodeposition of Ni with Cr
or/and Al nanoparticles were proposed. A brief review on the high temperature oxidation performance of
such novel electrodeposited nanocomposites like Ni-Cr, Ni-Al and Ni-Cr-Al is presented.
Comparison with Physics and Chemical Property of SBS/AA Copolymer Using Thermal Polymerization and UV Graft-Polymerization Methods
Authors: Chen Ko Shao , Chen Su Chen , Yeh Yi Chun , Lin Hong Ru , Lee Wen Fu , Lee Heng Hsien
Published: March 2009

This study was compare of physics and chemical property of Styrene-butadiene-styrene (SBS)/
Acrylic acid (AA) copolymer after thermal polymerization and UV graft-polymerization. The result
of this study shows: when the thermal polymerization was used, the grafting percentage of SBS-g-AA
rose along with the increase of the AA monomer concentration. The maximum occurred when
SBS=0.5g and AA=2.5 x 0.0065mol, then it decreased along with the increase of the AA
concentration. The transition ratio and grafting percentage decreased as the concentration of SBS
increased; while AA was fixed on 0.0065mol, the maximum grafting percentage occurred by using 1g
SBS. The grafting percentage increase along with the increase of reacting time, and it reached the
maximum after reacting 3 hours. The water contact angle was lowered from 82o to 58o. Using the UV
graft-polymerization, when AA monomer concentration increased, the grafting percentage increased
as well; the maximum occurred when AA concentration was 2.88M. Moreover, the grafting
percentage was increasing along with the increase of reacting time, but it stopped increasing around
40 minutes reacting time. The grafting percentage of thermal polymerization was higher than UV
graft-polymerization. It shows that the swelling ratio of membranes grafted using the UV light was
higher than those grafted by thermal polymerization.
Proton Exchange Membrane Development and Processing for Fuel Cell Application
Authors: Bébin Philippe , Galiano Hervé
Published: March 2009

The development of new proton exchange membranes for PEMFC has to be related to the
membrane processing as it can change drastically the final properties of the material. Indeed, for the
same material, a membrane prepared by a solvent-casting process has a lower lifetime than an
extruded one. The proton conduction of the membrane can also be dependent on the membrane
processing, especially when some removable plasticizers are used to perform the membrane
extrusion. Some residual porosity, left in the material after removing the plasticizer, is suspected to
enhance the proton conduction of the film. Fuel cell experiments have shown that extruded
sulfonated polysulfone membrane can give the same performance as a Nafion® reference
membrane whereas the proton conductivity of PSUs is twenty times lower than the Nafion® one.
Additional improvements of the membrane properties can also be expected by adding some proton
conductive fillers to the organic polymer. This approach enhances the proton conductivity of
sulfonated polysulfone to values similar to Nafion®. On the other hand, when Nafion® is used as a
matrix for the proton conductive fillers, a very significant improvement of fuel cell performance is
obtained.
Manufacturing and Oxidation Behavior of Silicide-Based Nanocomposite Coatings on Refractory Metals by Displacement Reaction
Authors: Yoon Jin Kook , Kum Dong Wha , Hong Kyung Tae
Published: March 2009

The microstructure and oxidation resistance of MSi2-SiC or MSi2-Si3N4
nanocomposite coatings (M = Mo, W, Nb, Ta) on M substrates formed by displacement
reactions between M-carbides or M–nitrides and silicon, respectively, was investigated. Present
study demonstrated that the crack density formed in the MSi2-base nanocomposite coatings due
to mismatch in the coefficient of thermal expansion between nanocomposite coatings and M
substrates could be controlled by adjusting the volume fraction of the SiC or Si3N4 reinforcing
particles with the low CTE values. The high- and low-temperature oxidation resistance of
nanocomposite coatings was superior to that of monolithic MSi2 coatings.
Ni-Fe Bimetallic Anode for Intermediate Temperature Solid Oxide Fuel Cells Using LaGaO3 Based Oxide Electrolyte
Authors: Ishihara Tatsumi , Shinagawa Masashi , Kawakami Akira , Matsumoto Hiroshige
Published: March 2009

Effects of various additives to Ni anode on SOFC using La0.9Sr0.1Ga0.8Mg0.2O3 based
oxide were investigated in this study. Among the examined additives, it was found that the
addition of small amount of Fe is highly effective for increasing the anodic activity. When 5 wt%
Fe was added to Ni anode, the anodic overpotential was as small as 34 mV at 873 K, 0.1A/cm2,
which is almost half of pure Ni anode. Since the estimated activation energy for anodic reaction
decreased, addition of Fe to Ni seems to be effective for increasing the activity of Ni for anodic
reaction. XRD measurement after power generating property suggests that added Fe was formed
alloy with Ni. SEM observation shows the high dispersion of Ni metal was sustained by addition of
small amount of Fe. Consequently, this study reveals that Ni-Fe bimetal is highly active for
anodic reaction of SOFCs at decreased temperature.
Synthesis and Sintering Behavior of Nano Crystalline Gd-Doped Ceria
Authors: Jo Seung Hwan , Kim Jong Ho , Kim Do Kyung
Published: March 2009

Two kinds of nano crystalline Gd-doped CeO2 particles were successfully synthesized via
glycine-nitrate combustion and neutral precipitation with subsequent hydrothermal crystallization. It
was revealed that the surface modification of nano particles significantly affected sintering
behaviors and resulting physical properties. Glycine/nitrate ratio was a key parameter to control the
surface state of nano particles in the glycine-nitrate process, but, in the neutral precipitation process,
the solvent was important. To obtain the GDC nano particles with chemically and physically
favorable properties, the effect of the surface state of nano particles on the sintering behavior was
discussed with consideration of aggregation property and surface-adsorbed substances on nano
particles.
Development and Demonstration of Membrane Reformer System for Highly-Efficient Hydrogen Production from Natural Gas
Authors: Yasuda Isamu , Shirasaki Yoshinori
Published: March 2009

A membrane reformer is composed of a steam reformer equipped with palladium-based
alloy modules in its catalyst bed, and can perform steam reforming reaction and hydrogen
separation processes simultaneously, without shift converters and purification systems. It thus can
be configured much more compactly and can provide much higher efficiency than the conventional
technologies. We have manufactured and tested a world-largest scale membrane reformer with a
rated hydrogen production capacity of 40 Nm3/h. The operation test has successfully been
proceeding for over 3,000 hours in one of the hydrogen refueling stations in Tokyo, which has
demonstrated the potential advantages of the membrane reformer: simple system configuration as
benefited by single-step production of high-purity (99.999% level) hydrogen from natural gas,
compactness and energy efficiency as high as 70 to 76% under both the rated and partial-load
operating conditions. The system has thus been proved to give the highest efficiency in producing
hydrogen from natural gas among various competing technologies. The paper will present the latest
achievements and the future plan of the membrane reformer technology development.
Mechanical Properties of a Spray-Cast Aluminum Alloy Processed by Severe Plastic Deformation
Authors: Xu Cheng , Kawasaki Megumi , Furukawa Minoru , Horita Z. , Langdon Terence G.
Published: March 2009

Experiments were conducted to evaluate the mechanical properties of a spray-cast Al-
7034 alloy processed by severe plastic deformation. The alloy was received with an average grain
size of ~2.1 μm and processed by equal-channel angular pressing (ECAP) at a temperature of 473 K
to give a grain size of ~0.3 μm after 6 or 8 passes. Following ECAP, the mechanical properties
were evaluated at room temperature (298 K) and at an elevated temperature of 673 K. In tensile
testing at ambient temperature, the stress-strain curves show very short regions of strain hardening
after ECAP and low values for the ultimate tensile strength by comparison with the unpressed alloy.
This lack of strength is due to the high pressures imposed by ECAP and the consequent
fragmentation and dissolution of the rod-like MgZn2 precipitates. It is shown that the strength may
be restored by performing an appropriate ageing treatment after ECAP. Superplastic ductilities
were recorded at a temperature of 673 K with tensile elongations exceeding 1000%. Careful
inspection of the polished surfaces of samples pulled to fracture in the superplastic condition
revealed the occurrence of extensive internal cavitation. Quantitative measurements showed the
development of these internal cavities is consistent with conventional superplastic alloys.
The Development of the Composite Materials for the Bipolar Plate of the Fuel Cell
Authors: Luo S.Y. , Chen Y.C. , Wen W.H.
Published: March 2009

The paper was to investigate the development of the graphite/phenolic resin composite
materials that were fabricated by compression molding for the bipolar plate of the fuel cell. Effect
of the different amounts of resin and the graphite powder size on the porosity, density, bending
strength, and electrical resistance of the composites would be analyzed. In addition, the composites
of the bipolar plates would be machined into the groove channel using high speed milling, which
then assembles into single fuel cell. The I-V performance of the single fuel cell would be also
discussed.
The experimental results showed that when the larger amount of resin was employed, the
resulting composites had a lower porosity, a larger electrical resistance, and a higher bending
strength. The graphite/resin composites showed a good machinability during the high-speed milling.
Finally, the graphite/resin composites of bipolar plates containing 25-30 vol. % phenolic resins were
fabricated into a single fuel cell, which displays a relatively better I-V performance.