bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure and Optical Properties of Fe-Doped SnO2 Nanoparticles Synthesized by Hydrothermal Method
Authors: Fang L.M. , Zu Xiao Tao
Published: March 2009

Fe-doped SnO2 nanoparticles have been synthesized by a simple hydrothermal method.
After Fe doping, the as-prepared SnO2 samples were calcined at different temperature from 350-800
°C in air for 1 h. The effects of Fe dopant and calcination on the microstructure and optical properties
are investigated using X-ray diffraction (XRD), High resolution transmission electron microscopy
(HRTEM) , UV-VIS diffuse reflectance spectra (DRS). Results show that the Fe-doped SnO2
crystallites with the rutile phase was directly synthesized during hydrothermal process without
calcination. A dramatically red shift in the absorbing band edge was observed with the decreasing
crystallite size result from the increasing Fe content.
Fabrication of Homogeneous Bulk Nanocrystalline Ni-W Alloys by an Electroforming Process
Authors: Fujii Akari , Kimoto Yoshihisa , Wakayama Shin , Takigawa Yorinobu , Uesugi Tokuteru , Higashi Kenji
Published: March 2009

Many studies have been conducted on mechanical properties in nanocrystalline Ni-W
alloys. However, since these results are obtained in the specimens whose thickness is less than 100
μm and whose homogeneity is not strictly controlled, an inherent potential of the nanocrystalline
Ni-W alloy may be hidden. Therefore, it is necessary to fabricate the bulk Ni-W alloy with
sufficient thickness and homogeneity. In the present study, we develop novel electroforming process
and fabricate the homogeneous nanocrystalline Ni-W alloys. The homogeneities of W-concentration
in micrometer scale are confirmed by the W-concentration profiles obtained by the linear analyses
of the energy dispersed spectroscopy (EDS). The single-phase nanocrystalline bulk Ni-W alloy with
the thickness above 2 mm and minimized W-concentration gradient and fluctuation is featured for
the first time.
Bulk Mechanical Alloying of Al/Fe Multilayer by Accumulative Roll-Bonding Process
Authors: Nakamura Takuro , Kitahara Hiromoto , Lee Jung Goo , Tsuji Nobuhiro
Published: March 2009

Pure Al (99%) and pure Fe (99.5%) sheets were mutually stacked and severely deformed up
to equivalent strain of 16 by the accumulative roll bonding (ARB) process in an attempt to achieve
bulk mechanical alloying. The deformation was carried out at RT. The Al/Fe sheets ARB processed
by 1 cycle showed a number of shear bands penetrating the stacked layers. The Fe layers, which were
harder than the Al layers, were subdivided by the shear bands into diamond-shaped regions.
Dissolution of Fe into Al was observed and a supersaturated solid solution was formed in the
specimen ARB processed by 10 cycles. It was also found that local amorphization occurred at
interface regions via formation of Al5Fe2 intermetallic compound.
Upsetting of Ultrafine-Grained Bulk Al-Mg Alloy Consolidated by Hydrostatic Extrusion
Authors: Kim E.Z. , Oh Soo Ik , Lee Sang Mok , Yoon C.Y. , Park Hoon Jae , Kim Seung Soo , Choi Tae Hoon , Na Kyoung Hoan
Published: March 2009

Deformation characteristics and forming limit of ultrafine-grained bulk Al-Mg alloy were
examined with upsetting process. The Al-7.5%Mg alloy produced by cryogenic milling and HIP was
subjected to hot hydrostatic extrusion as a final consolidation in fabricating the ultrafine-grained bulk
material. Upsetting was performed to study their mechanical characteristics in a practical forming
process. The extruded specimen showed that the pores remained in spite of the HIP had been
collapsed and almost eliminated. The effective removal of the distributed pores resulted in significant
increase of formability by preventing early cracking. Metallographic investigations showed that the
size of grain remained below a few hundred nanometer scale in the processes.
Glass Transition within the Cluster Variation Approximation
Authors: Mohri Tetsuo
Published: March 2009

The detailed behavior of the free energy of Cluster Variation Method in the vicinity of
spinodal ordering transition is examined. The generalized phase diagram proposed in the previous
study is modified and spinodal ordering transition is reinterpreted as a limiting case of the ideal glass
transition.
Synthesis of Zr-Based Glassy Alloy Foams
Authors: Prasada Rao A.K. , Oh Yoon S. , Kim Nack
Published: March 2009

The present basically concerns with the synthesis of foamy structured amorphous Zrbased
alloy, Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit-1), by liquid state processing. In this method, melt was
injected in to the evacuated interstitial voids of the NaCl crystals placed in a copper mould. The
casting has been subsequently washed with a jet of water to ensure the removal of NaCl entrapped
in the casting, thus resulting in a porous structured casting. It shows the possibility of synthesizing
amorphous metal foams with large dimensions using salt infiltration technique.
Fine Crystalline Phase Dispersion in Zr-Based Bulk Metallic Glass by Laser Irradiation
Authors: Ikutomo R. , Tsujikawa Masato , Hino Makoto , Kimura Hisamichi , Yubuta Kunio , Inoue Akihisa
Published: March 2009

Bulk metallic glass (BMG) exhibits remarkable properties such as high strength, good
stiffness and good corrosion resistance. However, the wear resistance of amorphous metals is not
excellent as expected their high strength. It is thought that large local shear bands easily change into
cracks for debris formation. The effective obstruction of shear band formation might be applied to
improve the wear resistance of BMG. In this study, we tried to suppress shear band deformation by
fine crystalline phase dispersion formed by semi-conductor laser irradiation. The microstructures of
irradiated Zr-based BMG specimens were characterized by X-ray diffraction (XRD) and scanning
electron microscope (SEM). The fine dispersions of crystalline phases are observed in the amorphous
matrix. The optimum condition for laser irradiation was discussed.
Microstructure and Mechanical Properties of Hot-Pressed Co-Cr-Mo Alloy Compacts
Authors: Sato Yoshimi , Nomura Naoyuki , Fujinuma S. , Chiba Akihiko
Published: March 2009

The microstructure and mechanical properties of compacts produced from hot-pressing the
Co-29Cr-6Mo alloy powder, fabricated by gas atomization, were investigated in this study. The
average diameter of the alloy powder is 41 μm. Electron probe micro analysis revealed that the
concentration scattering of chromium and molybdenum is relatively small between the powders. The
compact hot-pressed at 1273 K in Ar with an applied pressure of 80 MPa possesses the relative
density of 97% and the fine grain (2.7 μm). The ultimate tensile strength of the compact is 1240 MPa,
which is comparable to that of the forged Co-29Cr-6Mo alloy.
Effect of Sigma Phase in Co-29Cr-6Mo Alloy on Corrosion and Mechanical Properties
Authors: Kurosu Shingo , Nomura Naoyuki , Chiba Akihiko
Published: March 2009

Effect of the sigma (σ) phase in Co-29Cr-6Mo alloy on corrosion and mechanical behavior has
been investigated. The area fraction of the σ phase varies depending on the aging time at 1023 K. The area
fraction of the sigma phase increases with increasing aging time and reaches 0.6 % after aging at 1023 K for
21.6 ks. Inductively coupled plasma atomic emission spectrometer (ICP-AES) analysis revealed the quantity
of released Co ion shows almost the same values regardless of different area fraction of the σ phase. In
addition, plastic elongation and 0.2% proof strength exhibit almost the same values, although the alloys have
different area fraction of the σ phase. These results suggest that a small amount of the σ phase (<0.6%) hardly
affect the corrosion and mechanical properties in the Co-29Cr-6Mo alloy.
Effect of Second Phase Particles on Phase Stability of Zirconia in Hot Water
Authors: Shibano T. , Takigawa Yorinobu , Uesugi Tokuteru , Higashi Kenji
Published: March 2009

The effect of second phase particles on tetragonal to monoclinic (t-m) phase
transformation of zirconia is examined, which causes the degradation of zirconia in vivo. Silica is
selected as the second phase particles and dispersed 0.1 to 10mol% into 3mol% yttria stabilized
tetragonal zirconia polycrystal (3Y-TZP). As the result, phase transformation is promoted in all the
samples examined in comparison with 3Y-TZP. Non-dispersed specimen exhibits better phase
stability than that in silica doped one. Since the thermal expansion coefficient is smaller in order of
silica and zirconia, the residual stresses induced during cooling from the sintering temperature must
be the dominant factor to determine the phase stability in these materials.
Raman Spectroscopic Characterization for Carbon Nanofibers Produced by Using Ferric Chloride of Different Concentration as Catalyst Precursor
Authors: Li Fei , Zou Xiao Ping , Cheng Jin , Zhang Hong Dan , Ren Peng Fei , Zhu Guang , Wang Mao Fa
Published: March 2009

Catalytic grown carbon nanofibers have been obtained from decomposition of ethanol over
copper plate. Ferric chloride of different concentration was employed as the catalyst precursor.
Scanning electron microscopy has shown that different morphologies of carbon nanofibers can be
obtained by using different concentration of catalyst precursor solution. The results from the Raman
spectroscopic characterization have also demonstrated that the graphitization of carbon nanofibers
can be tailored by control of the concentration of catalyst precursor solution. When the information
from these characterization are combined with that of the associated morphologies of the carbon
nanofibers, it is possible to synthesize perfect carbon nanofibers.
Electrochemical Properties of TiN and ZrN Coated Ti-Hf Alloy
Authors: Jeong Yong Hoon , Choe Han Cheol , Park Su Jung , Ko Yeong Mu
Published: March 2009

The Ti-Hf alloy system forms α-β isomorphous system and does not form any
intermetallic compounds, which is also beneficial for good mechanical properties. And in order to
avoid the release of materials, surface modifications are generally carried out to form a TiN and
ZrN layer on the surface. Electrochemical properties of TiN and ZrN coated Ti-Hf alloy by RFsputtering
has been researched using various electrochemical methods.
Ti-10wt%, 20wt%, 30wt%, and 40wt% Hf alloys manufactured by non consumable vacuum arc
melting furnace. All the specimens were heat treatment at 1000°C for 24hr in Ar atmosphere
followed by furnace cooling, respectively. The specimens were coated with TiN and ZrN
respectively, by RF-magnetron sputtering method. The microstructures were conducted by using
OM, EDX and SEM. The corrosion tests were carried out using potentiodynamic(PARSTAT 2273,
EG&G, USA) and potentiostatic test in 0.9% NaCl solution at 36.5 ±1 °C. Microstructure clearly
observed that lamellar structure translated to needle-like structure with increased Hf contents. From
the analysis of TiN and ZrN coated layer analysis, TiN and ZrN coated surface showed columlar
structure with 600nm and 100nm thickness, respectively. The corrosion resistance of TiN and ZrN
coated Ti alloys were higher than those of the non-coated Ti-alloy in 0.9%NaCl solution, indicating
better protective effect.
Effects of Multi-Layered TiN/ZrN/Tooth-Ash Composite Coatings on the Surface Characteristics of Ti-(Nb, Zr, Ta, Hf) Dental Implant Alloys with Low Elastic Modulus
Authors: Choe Han Cheol , Brantley William A.
Published: March 2009

Effects of TiN, ZrN and tooth-ash coatings on the surface phenomena of Ti-(Nb, Zr, Ta,
Hf) dental implant alloys with low elastic modulus has been researched by using electrochemical
methods. Ti-(Nb, Ta, Zr, and Hf) alloys were fabricated and surface-coated with TiN, ZrN and
tooth-ash (hydroxyapatite) using the RF-sputtering. The electrochemical behaviors of the TiN, ZrN
and HA-coated dental implant fixtures were investigated using techniques such as potentiodynamic
polarization analysis in 0.9% NaCl solution, as well as examine the detailed structure of these
coated alloys using SEM and XRD. From potentiodynamic test of Ti-(Nb, Zr, Ta, Hf) alloy, the
corrosion resistance of TiN/ZrN/tooth-ash composite coated Ti-(Nb, Zr, Ta, Hf) alloy were higher
than those of the non-coated Ti-(Nb, Zr, Ta, Hf) alloy.
Progress on the Composite Membranes for PEM Fuel Cells
Authors: Zhang Hua Min
Published: March 2009

In this paper, R & D on the reinforced and self-humidifying composite membranes for
proton exchange membrane fuel cells (PEMFCs) in our group is presented. It is shown that both the
reinforced and self-humidifying membrane have attained an enhanced performance.
Improvement of Electrical and Thermal Properties of Epoxy Based Graphite Bipolar Plate for PEMFC
Authors: Lee Hong Ki , Chae Soo Heun , Shim Joong Pyo , Yang Sung Won
Published: March 2009

The decrease of material cost for manufacturing fuel cell stack is strongly required for
overcoming commercial restriction. The epoxy based graphite bipolar plate (BP) for polymer
electrolyte membrane fuel cells (PEMFC) has been prepared and electrical, mechanical and thermal
properties were compared. The density of graphite composite bipolar plate showed from 1.67 to
2.54 as graphite content is increased from 60 to 80w/o and decreased as expanded graphite was
added. The contact resistance between epoxy/graphite bipolar plate and gas diffusion layer (GDL)
had lower value using carbon cloth than carbon paper for GDL. The conformation of thermal
stability, improvement of mechanical and electrical properties was accomplished by addition of
expanded graphite powder.
Effect of Ni Coating on Hydrogenation Kinetics in Pure Mg and Mg-Mg2Ni Eutectic Alloy
Authors: Kusumoto Masaaki , Saitoh Hideyuki
Published: March 2009

We have applied hybridization method to the surface modification by Ni coating on powder
specimens of pure Mg and Mg-Mg2Ni eutectic alloy, and investigated the effect of the Ni coating on
the hydrogenation kinetics in them. The hydrogenation kinetics at 350 degree C is greatly
increased by the Ni coating for both the pure Mg and Mg-Mg2Ni eutectic alloy specimens. Thus,
it is confirmed that the surface modification by the hybridization method is considerably effective to
improve the hydrogenation kinetics in them. This improvement is thought to be a catalytic effect
of the coated Ni. The hydrogenation kinetics of the Mg-Mg2Ni alloy specimen heat-treated at 470
degree C has increased compared with that of the as-cast alloy specimen. It is also confirmed that
hydrogenation kinetics improves by the heat treatment to grow the eutectic structure consisted of
Mg2Ni phase and Mg phase.
Electronic Transport Properties of Tin-Filled Cobalt Antimonides
Authors: Jung Jae Yong , Ur Soon Chul , Kim Il Ho
Published: March 2009

The encapsulated induction melting was attempted to prepare the Sn-filled CoSb3
skutterudites and their electronic transport properties were investigated. Single phase δ-CoSb3 was
successfully obtained by the subsequent isothermal heat treatment at 823K for 6 days in vacuum.
The Sn-filled CoSb3 showed p-type conductivity at 300K to 700K at it is a highly degenerate
semiconductor. Lattice contribution was dominant to thermal conductivity and it was considerably
reduced by Sn filling in the CoSb3 skutterudite.
Combustion Synthesis in Mn-Si-C-N Using Mn as a Surrogate for Am
Authors: Shen Wei Ping , Ge Chang Chun , Zhang Li Feng , Pan Tian Yong
Published: March 2009

The paper outlined here uses self-propagating high-temperature synthesis (SHS) or
combustion synthesis that employs more efficient and effective high reaction and cooling rates to
produce high quality, reproducible nitride fuels. The fundamental SHS processing parameters was
determined to produce Mn-Si-C-N ceramic compounds in which Mn is a surrogate for Am. Because
manganese nitride has a relatively low heat of formation the reaction can not be self-sustaining when
Si was blended with Mn in the Si:Mn=0.25:1 ratio. The purity of MnSiN2 increases with an increase
of the Mn content in Mn-Si-N system. Pure MnSiN2 can be synthesized when Si was blended with Mn
in the Si:Mn = 0.5:1 ratio. Volume expansion and porosity decreases, so density, strength and
hardness increase as increasing the Mn content in Mn-Si-N system. The powders and sintered cake of
MnSiN2-Si3N4 or MnSiN2-Si3N4-SiC was produced by combustion synthesis. The sintered cake of
MnSiN2-Si3N4-SiC is attacked by atmospheric moisture to fall to a powder.
A New Growth Kinetics in Simulation of Dendrite Growth by Cellular Automaton Method
Authors: Shan Bo Wei , Lin Xin , Wei Lei , Huang Wei Dong
Published: March 2009

A modified cellular automaton model was proposed to simulate the dendrite growth of
alloy. Different from previous models, this model used neither an analytical equation(such as KGT
model) nor an interface solute gradient equation to solve the velocity of solid-liquid interface, but
used the interface solute and energy conservation and thermodynamic equilibrium condition to
describe the solid/liquid interface growth kinetics process. In present model, once the temperature
field and solute field were solved by finite different method in the entire domain, the material
thermodynamic properties can be substituted into four algebraic equations to easily determine the
variation of solid fraction, interface temperature and solute concentration, instead of calculating
interface moving velocity. As a result, the complexity of the calculation can be largely reduced. The
simulated dendrite growth was in a good agreement with the Lipton–Glicksman–Kurz (LGK) model
for free dendritic growth in undercooled melts.
Electronic State Calculation of Manganese Dioxide and Manganese-Molybdenum Oxide for Dimensionally Stable Anode
Authors: Kim B.S. , Lee Dong Yoon , Lee Hee Woong , Chung Won Sub
Published: March 2009

The effect of molybdenum substitution in electronic structures of manganese dioxide has been
calculated by the DV-Xα molecular orbital method. The molybdenum atom substituted for manganese atom
located in center-sited of (Mn15O56)-52 cluster model. By the molybdenum substitution the energy band gap
between the highest occupied molecular orbital (HOMO) of valence band and the lowest unoccupied
molecular orbital (LUMO) was decreased, also the interaction of Mn-3d and O-2p was weakened but that of
Mo-4d and O-2p was intensified. Both bonds of (Mn15O56)-52 and (Mn14MoO56)-52 was composed of not only
ionic but also partially covalent.
Application of RBF Network for Forecasting Characteristics of In-Flight Particles by Plasma Spraying
Authors: Gao Y.Q. , Fang Jian Cheng , Zhao Zhi Yu , Yang L.
Published: March 2009

The main factors that influence the deposition efficiency and forming quality are the state
of in-flight particles, which are directly effected by process parameter during plasma spray forming.
In this study, plasma spraying of ZrO2 powder was employed according to the method of orthogonal
experiments, and the relationship between spray parameters and characteristics of in-flight particles,
which were monitored by an optical monitoring system of CCD camera, were investigated. Radial
basis function (RBF) neural network model had been designed to forecast the temperature and
velocity of in-flight particles, and optimized spray parameter. The comparison of the simulations
with the experimental results shows the validity of the model.
Numerical Simulation and Experimental Research on Rolling Process of Conical Ring with Inner Steps
Authors: Han Xing Hui , Hua Lin , Lan Jian
Published: March 2009

The Conical Ring with Inner Steps (CRIS) is a typical profile ring, which is hard to be
formed by ring rolling. Less-profile-filling and shrinking-drawing are the two main defects formed in
the rolling process. Through the study of the rolling formability of CRIS with different ratio of height
to diameter with the combination of FEM simulation method and experimental method, the main
factors that affect the CRIS rolling formability are determined. The CRIS forging is designed. And
the FEM simulation and experimental results show that the design method is reasonable.
Ultrafine Grained Ti-47Al-2Cr (at%) Alloy Prepared by High Energy Mechanical Milling and Hot Isostatic Pressing
Authors: Nadakuduru Vijay , Cao Peng , Zhang De Liang , Gabbitas Brian
Published: March 2009

Gamma TiAl based alloys are important materials with potential applications in aerospace and automotive applications due to their high specific strength and creep resistance. The major barrier for their applications is their limited ductility at room temperature and limited hot workability. One way of overcoming this barrier is to reduce the grain sizes to ultrafine grained (<500μm) or nanostructured (<100nm) level. In our present study, we attempt to produce bulk ultrafine grained Ti- 47Al-2Cr (at%) alloy using a combination of high energy mechanical milling of elemental powders to produce a very fine structured Ti/Al/Cr composite powder and consolidation of the powder using hot isostatic pressing (HIPping). It was confirmed that high energy ball milling using a planetary ball mill led to the formation of extremely fine Ti and Al layered composite structure. The thermal behaviour of the powder was studied using differential thermal analysis, and it was shown that the reactions between the Ti and Al phases in the fine structured composite powder occur at fairly low temperatures, below the melting point of the Al phase (660oC). The macrostructure and phase structure of the HIPped samples were also examined using optical and scanning electron microscopy and X-ray diffractometry (XRD). This paper is to report and discuss the results of this investigation.
Effect of Composition on the Morphology and Hardness of Nanostructured Cu Based Composite and Alloy Powders/Granules Produced by High Energy Mechanical Milling
Authors: Mukhtar Aamir , Zhang De Liang , Kong C. , Munroe P. R.
Published: March 2009

Cu-(2.5 or 5.0vol.%)Al2O3 nanocomposite balls and granules and Cu-(2.5vol.% or 5.0vol.%)Pb alloy powder were prepared by high energy mechanical milling (HEMM) of mixtures of Cu and either Al2O3 or Pb powders. It was observed that with the increase of the content of Al2O3 nanoparticles from 2.5vol.% to 5vol.% in the powder mixture, the product of HEMM changed from hollow balls into granules and the average grain size and microhardness changed from approximately 130nm and 185HV to 100nm and 224HV, respectively. On the other hand, HEMM of Cu–(2.5 or 5.0vol.%) Pb powder mixtures under the same milling conditions failed to consolidate the powder in-situ. Instead, it led to formation of nanostructured fine powders with an average grain size of less than 50nm. Energy dispersive X-ray mapping showed homogenous distribution of Pb in the powder particles in Cu–5vol.%Pb alloy powder produced after 12 hours of milling. With the increase of the Pb content from 2.5 to 5.0 vol.%, the average microhardness of the Cu-Pb alloy powder particles increases from 270 to 285 HV. The mechanisms of the effects are briefly discussed.
New Ceramic Membrane Materials for Gas Purification
Authors: Brown Ian William Murray , Bowden M.E. , Kemmitt T. , Kirchner A. , MacKenzie Kenneth
Published: March 2009

This paper examines processes for the preparation and characterisation of new ceramic membrane materials with potential for gas purification, based on nanostructured anodic alumina. The ultimate research goal is to develop a membrane capable of separating hydrogen from hot synthesis gas so a key factor is the ability of the membrane to operate successfully at temperatures in excess of 800°C. Two membrane materials are compared and contrasted: a commercial Whatman product and a membrane prepared in our laboratory. We have demonstrated that the fabrication conditions, most particularly the acid environment used during membrane fabrication, controls and directs the high temperature behaviour of the membranes. Membranes prepared using sulphuric acid electrolytes have been shown to withstand 800°C without distortion and without compromising their nanostructured pore array.
Consolidation of TiAl Powder by Thermal Spray Processes
Authors: Cao Peng , Gabbitas Brian , Salman Asma , Zhang De Liang , Han Z.H.
Published: March 2009

Thermal spray deposition has been widely used as a coating process for applying thin
protective layers to the need-to-protect materials, or substrates. Recent technological developments
in thermal spray processing, particularly cold gas spraying (CGS) and supersonic plasma spraying
(S-PS), have enabled some emerging applications for making structural components. This paper
reports on the results of our recent attempts to obtain thick TiAl coatings using three coating
techniques: atmospheric plasma spraying (APS), S-PS and CGS. We successfully achieved a 3 mm
thick coating using both APS and S-PS techniques, but failed in cold spray. A significant phase
change was observed of the powder particles experienced during both APS and S-PS processes.
Nevertheless, a considerable quantity of titanium oxides was observed in the APS coating.
Control of Shell Thickness in Silica-Coating of AgI Nanoparticles
Authors: Kobayashi Y. , Misawa K. , Takeda M. , Ohuchi N. , Kasuya A. , Konno M.
Published: March 2009

Silica-coating of AgI nanoparticles with a Stöber method was carried out to find out reaction conditions for control of the shell thickness. The AgI nanoparticles were prepared from AgClO4 and KI with the use of 3-mercaptopropyltrimethoxysilane (MPS) as a silane coupling agent and dimethylamine (DMA) catalyst for alkoxide hydrolysis. The silica-coating was performed at 4.5×10-6-4.5×10-5 M MPS, 11-20 M water, 0.002-0.1 M DMA and 0.005-0.04 M tetraethylorthosilicate at AgI concentrations of 0.1-1 mM. Consequently, AgI-silica core-shell particles could be prepared with the use of 4.5×10-5 M MPS, 20 M water, 0.01 M DMA and 1 mM AgI. Silica shell thickness could be varied from 15 to 28 nm with an increase in the TEOS concentration from 0.005 to 0.04 M.
Synthesis and Characterisation of Titania Nanotubes: Effect of Phase and Crystallite Size on Nanotube Formation
Authors: Morgan D.L. , Waclawik E.R. , Frost R.L
Published: March 2009

Nanotubes were produced from commercial and self-prepared anatase and rutile which
were treated with 7.5 M NaOH over a temperature range of 100 – 200°C in 20°C increments. The
formation of nanotubes was examined as a function of starting material type and size. Products
were characterised by X-Ray Diffraction (XRD), Transmission Electron Spectroscopy (TEM), and
Raman Spectroscopy. The results indicated that both phase and crystallite size affected the
nanotube formation. Rutile was observed to require a greater driving force than anatase to form
nanotubes, and increases in crystallite sizes appeared to impede formation slightly.
Direct Shaping of Alumina Ceramics by Electrophoretic Deposition Using Conductive Polymer-Coated Ceramic Substrates
Authors: Uchikoshi Tetsuo , Furumi Seiichi , Suzuki Tohru , Sakka Yoshio
Published: March 2009

Cathodic electrophoretic deposition of bimodal alumina suspension was performed using conductive polypyrrole (Ppy) film as an electrode. The coating of the Ppy on nonconductive ceramic substrates was performed by polymerization of pyrrole (Py) in an aqueous solution. The relative green density of the deposits measured by Archimedes’ method was 68 %. Alumina ceramics were obtained by sintering the deposits together with the Ppy coated ceramic substrates in air.
High-Frequency Induction Heating Sintering of Ultra-Fine Al2O3-(ZrO2+X%mol Y2O3) Bioceramics
Authors: Kim S.W. , Khalil Khalil Abdel-Razek , Ogi K.
Published: March 2009

Alumina–zirconia composites Al2O3–20 vol. % yttria stabilized zirconia containing two types of yttria stabilized zirconia: 3mol% yttria doped ZrO2 and 8mol% yttria doped ZrO2 were consolidated very rapidly to full density by high frequency induction heating sintering (HFIHS). A comparison between 3YSZ and 8YSZ as a second phase toughening alumina has been made. Effects of sintering temperature on the mechanical properties have been studied. The consolidated samples were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The microhardness, strength and toughness of the composites are determined. The results showed that, 3YSZ is most effective as a second phase toughening alumina then 8YSZ. Al2O3-3YSZ composites with higher mechanical properties and small grain size were successfully developed at relatively low temperatures through this technique.
The Abrasive Wear of Alumina Matrix Particulate Composites at Different Environments of Work
Authors: Pędzich Zbigniew
Published: March 2009

The paper presents the results of investigation on the wear of alumina-based composites
containing submicrometre particles of other phases in different conditions of work. Three types
of phases were used as additives: tungsten carbide, yttria stabilized zirconia and metallic tungsten.
The above mentioned phases were used separately or simultaneously as mixes. Two types of tests
were performed - the Dry Sand Test and the Miller Test in wet pulp. Coarse silicon carbide grains
were used as an abrasive medium in both cases. The results indicate that the optimal wear
susceptibility in given work environment could be achieved by the addition of different type of
additives.
Evaluation of the Mechanical Properties of Injection Moulded Hemp Fibre Reinforced Polypropylene Composites
Authors: Beckermann G.W. , Pickering K.L. , Foreman N.J.
Published: March 2009

In recent years, industrial hemp fibre reinforced thermoplastic composites have attracted
substantial interest as potential structural materials. These composites have been subject to intense
study for use in lightweight, recyclable and low cost applications. The aim of this research was to
improve and evaluate the composite tensile strength and fibre/matrix interfacial adhesion by means
of fibre treatment and addition of a coupling agent. Hemp fibre was digested in a small pressure
vessel with a solution of 5wt% NaOH / 2wt% Na2SO3. Single fibre tensile tests were performed on
treated and untreated fibres, and it was found that the alkali treatment resulted in an increase in fibre
strength and an improvement in fibre separation. Composites containing either treated or untreated
fibre, polypropylene and a maleic anhydride modified polypropylene (MAPP) coupling agent were
then compounded in a twin-screw extruder and injection moulded into tensile test specimens.
Tensile tests revealed that significant improvements in composite strength were made by using
treated fibre and MAPP. The effect of MAPP on the interface of treated hemp fibre/polypropylene
composites was assessed by means of the single fibre fragmentation test, and the interfacial shear
strength was determined thereafter.
The Effects of Residual Lignin Content on Wood Fibre Reinforced Polypropylene Composites
Authors: Beg M.D.H. , Pickering K.L.
Published: March 2009

This study investigates the effect weathering on composites made from fibre subjected to
various stages of a standard Kraft pulping process. Pre-washed, washed and bleached Kraft wood
fibre of kappa numbers 27, 17, and 1 was assessed in terms of its surface potential using the
streaming potential method and combined with polypropylene (PP) to produce composites.
Composites were prepared using a twin screw extruder followed by pelletising and injection
moulding. Tensile testing, hardness testing and impact testing were carried out to evaluate the
composite mechanical properties. It was found that fibre with higher amounts of residual lignin
content led to composites with lower tensile and impact strengths and increased degradability when
subjected to accelerated weathering testing.
Electrical Properties of Mn-Co-Ni Oxides Prepared at Low Temperatures
Authors: Yokoyama T. , Meguro Takeshi , Okazaki S. , Fujikawa H. , Ishikawa T. , Tatami Junichi , Wakihara Toru , Komeya Katsutoshi , Sasamoto T.
Published: March 2009

Changes in crystal phase and electrical properties of oxides composed of Mn, Co, and Ni
with the molar ratios of 5:2:1 and 3:3:1 were investigated. Starting oxides were fired from 250°C to
800°C, then maintained at prescribed temperatures for 3 h in air. In the 5:2:1 specimen, a monophase
consisting of a cubic spinel oxide that is important to electrical conductivity was obtained at firing
temperature of 800°C. In the 3:3:1 specimen, the monophase was obtained at temperatures ranging
from 600°C to 800°C. Electrical resistance decreased exponentially with increasing temperature for
all specimens fired at temperatures ranging from 250°C to 800°C, indicating that the oxides have
intrinsic thermistor characteristics with negative temperature coefficient (NTC). The temperature
dependence of the thermistor constant (B value) necessary for practical application was considered to
be related to the existence ratio of cubic spinel-type and ilmenite-type structures and the lattice
constant of the cubic spinel-type structure. The electrical conduction was stabilized by annealing at
prescribed temperatures for more than 720 minutes.
Characterization of Indentation Size Effect of Hardness Using a Loading Curve from Crystalline Materials
Authors: Chiu Y.L. , Ferguson W. George
Published: March 2009

Nanoindentation technique has been widely used for measuring mechanical properties
from a very small volume of material. The hardness measured using the depth sensing
nanoindentation technique often decreases with increasing indentation size, the so called
indentation size effect (ISE)[1, 2]. It has been generally acknowledged that the ISE in crystalline
materials originates from the density change of geometrically necessary dislocations (GND) needed
to accommodate a permanent indentation imprint. Conventionally, to characterize an ISE often
requires a series measurement of hardness values at different indentation size. Based on the
celebrated Oliver-Pharr scheme[3]. We propose a method to derive the ISE from the loading curve
of one single indentation test. The application and limitation of the proposed method will be
discussed.
Fabrication of High Mg Containing Al-Mg Alloy Sheets by Twin Roll Strip Casting
Authors: Kim Hyoung Wook , Lim Cha Yong , Kang Suk Bong
Published: March 2009

Al-Mg alloy sheets with high Mg contents (3~10wt%Mg) were fabricated by twin roll strip casting. The optimum process conditions to get a good surface quality of Al-Mg strip have been suggested in this experiment. Controlling the cooling rate of cast roll was important to improve the surface quality of the strip and a compositional homogeneity through the thickness. The size of intermetallic particle like Al-Fe compound was reduced down to 1~2μm due to a high cooling rate of Al melt during strip casting. In addition, the dendrite structure was fine and the segregation of Al8Mg5 phase between grains was remarkably reduced. Therefore, the strips with a thickness of 3mm have good workability during additional hot/warm rolling processes. The hot/warm rolled Al-5wt%Mg sheets show high strength and elongation. When the rolled sheets were annealed at 300 oC for 1hr., the tensile strength and total elongation of the sheets reached at 290 MPa and 30%, respectively.
Synthesis and Characterization of Nitrogen Implanted Titanium Alloys
Authors: Choi B.Y. , Jeong J.K. , Lim Y.B.
Published: March 2009

Nitrogen implanted titanium alloys with enhanced wear resistance have been synthesized
under the conditions of energy and N++N2
+ion dose in the range of 30keV to 120keV and
3×1017ions/cm2 to 1×1018ions/cm2, respectively. Auger electron spectroscopy and X-ray diffraction
show that supersaturated titanium solid solution with the gradient nitrogen concentration and
titanium nitride compounds are formed in the surface modified regions of the materials. Enhanced
wear resistance of the nitrogen implanted titanium alloy at energy of 120keV and ion dose of
1×1018ions/cm2 has been showed and explained on the basis of observed microstructure including
the formation of micropits on the wear track in the present study.
Optical and Structural Properties of Multi Deposition Film Derived SiO2-TiO2 Systems by Sol-Gel Process
Authors: Malik M.Z.A. , Zainuddin M.T. , Abdullah A.M. , Isnin A.
Published: March 2009

SiO2-TiO2 systems were extensively investigated in sol-gel process to fabricate passive optical planar waveguides, channel waveguides, interference filters and weather resistant optical memory discs. A high quality, crack free optical thick layer and low processing cost are key success factor for optical applications. Two formulated SiO2-TiO2 systems with 1% and 10% TiO2 were deposited on 20mm x 20mm Si-wafer using multi-spin coating process was investigated on refractive index (n), build-up layer until crack appeared on film. The structure analysis of multi spin was investigated using FTIR. The value of refractive index (n) and thickness of thin films (d) were taken every deposited layer using spectroscopic reflectance and surface morphology of crack thick film by FESEM. SiO2-TiO2 thin film appeared peak ~950cm-1 associated with the Si-O stretching vibrations of Si-OH and Si-O-Ti groups by multi spin coating processes. SiO2-TiO2 system with 10% TiO2 in siloxane structure was found capable on building thick layer up to 2.4 μm at 17 time cycles spins and heat treatments at 680 oC. The value of n was reduced with increasing of number of cycles and believes to form nanoporous zones between interfacial layers during hydrolysis and condensation process of each layer by multi spin coating process.
Raman study of Epitaxial lateral Overgrowth of GaN on Patterned Sapphire Substrate
Authors: Kang D.H. , Song Jae Chul , Song H. , Kim Dong Wook , Lee I.H. , Santhakumar Kannappan , Lee Cheul Ro
Published: March 2009

Structural and optical properties of gallium nitride (GaN) epilayers grown on lens shape
patterned sapphire substrate (PSS) using metalorganic chemical vapor deposition (MOCVD) for
various growth times were evaluated. From Raman spectra, a blue shift and reduction in the FWHM
of Raman modes of GaN grown on PSS were observed when compared to GaN grown on
unpatterend sapphire substrate (UPSS). From the DCXRD spectra, full width at half maximum
(FWHM) value was decreased with increasing growth time. FWHM of the sample grown at 80 min
was 473.5 arc sec. This indicates that there is an improvement in crystalline quality of the GaN
grown on PSS as the growth time increases. From photoluminescence (PL) spectra, an increase in
band edge emission intensity and a decrease in defect related yellow luminescence were observed
for GaN on PSS as the growth time increased.
In Situ Visualization of Layer Transitions during Convective Self-Assembly in a Sessile Drop
Authors: Gao Li , Yan Qing Feng , Wong C.C. , Chiang Yet Ming
Published: March 2009

Convective self-assembly of colloidal spheres provides a simple method for fabricating two and three dimensional colloidal crystals. In this work, we investigated the layer transitions phenomena during colloidal self-assembly in a sessile drop by using an in-situ videoscopic set-up. The effects of surface charge, colloidal concentration, and surfactant additions were examined. The results show that the chemical environment plays an important role in colloidal self-assembly. In the case of ordered growth, different layer transition phenomena were observed when the colloidal concentration is different.
In–Mole-Fraction and Thickness of Ultra-Thin InGaAs Insertion Layers Effects on the Structural and Optical Properties of InAs Quantum Dots
Authors: Boonpeng P. , Panyakeow S. , Ratanathammaphan S.
Published: March 2009

InAs quantum dots (QDs) have been grown by solid-source molecular beam epitaxy on
different InxGa1-xAs (0 ≤ x ≤ 0.3) to investigate the effect of In-mole-fraction and thickness of
InGaAs insertion layer (IL) on the structural and optical properties of the QDs. The density of QDs
directly grown on GaAs is 1×1010 cm-2, and increase to 1.4-1.8×1010 cm-2 on InGaAs layers which
depend on the In-mole-fraction and thickness of InGaAs layers. The effects of In-mole-fraction and
thickness of InGaAs insertion layer on optical properties of the QDs are studied by
photoluminescence (PL). The FWHM of PL spectrum corresponds to the size distribution of the
QDs.
Morphology and Crystal Quality of InAs QDs Grown by MOVPE Using Different Growth Modes
Authors: Yin Zong You , Tang Xiao Hong , Zhang Ji Xuan , Sentosa Deny , Teng Jing Hua , Du An Yan , Chin Mee Koy
Published: March 2009

Morphology and crystal-quality of InAs/In0.53Ga0.47As/InP quantum dots (QDs) grown by
metal-organic vapor phase epitaxy (MOVPE) in N2 ambient using different growth modes have
been studied. It is found that the morphology and crystal-quality of InAs QDs are dependant on the
growth modes. After optimizing the dots’ growth modes, dots’ size dispersion and crystal-quality
are both improved greatly, resulting in the enhancement factor of ∼ 2.9 in the photoluminescence
(PL) peak-intensity from single QD. When the dots are buried, the dot size decrease compared with
the free-standing dots due to the soon capping layer deposition during dots’ being buried. The
thermal activation energy measured is comparable to the valence-band offset in the QD system
calculated by 8 kp theory model. This indicates the PL quenching induced by the interface defects is
suppressed due to the defect density lowering in the QDs grown by such optimized growth mode.
Higher Crystalline Volume Yields from Excimer Laser Crystallization of Amorphous Silicon with an Asymmetrical Peak Pulse Profile
Authors: Adikaari A.A.D.T. , Mudugamuwa N.K. , Silva S.R.P.
Published: March 2009

Excimer lasers have been utilized for the crystallization of hydrogenated amorphous silicon for electronic applications. These lasers typically operate in the ultraviolet and hence photons are absorbed by the silicon thin films within a few nanometres of the surface, melting and solidifying the silicon on a nanosecond timescale, often without affecting the underlying substrate. This technique enables the use of inexpensive substrates, such as glass, which are highly preferable for low cost, large-area electronic devices. The depth of crystallization becomes important for applications such as photovoltaics, which depends on a number of factors; with laser beam shape one of the most significant. A Gaussian beam profile has been reported to be best suited for controlled evolution of hydrogen during crystallization with minimum surface damage. Previous reports show the typical energy densities of crystallization, comparing the crystalline volume and surface roughness of the resultant films for different film thicknesses. We report significant reductions of laser energy densities for crystallization by modifying the Gaussian pulse profile, while retaining the controlled evolution of hydrogen from hydrogenated amorphous silicon films. An asymmetrical, shorter pulse profile retains the desirable gradual leading edge of the Gaussian pulse for controlled evaporation of hydrogen, while increasing the peak energy. The resultant films show increased surface roughness along with higher crystalline volumes, which may be beneficial for photovoltaics.
Electrical Properties and UV Response of Single ZnO Nanorod
Authors: Le Hong Quang , Chua Soo Jin
Published: March 2009

Single ZnO nanorods with diameters of 100nm were directly grown on GaN surface by using low-temperature hydrothermal synthesis. Individual nanorods were removed from the substrate and placed between the Au contact pads and the current voltage measurement was proceeded to characterize the electrical properties of the ZnO nanorods. By using thermionic field emission model of Padovani and Stratton , the resistivity, carrier concentration, electron mobility can be extracted with the values of 0.14 Ωcm, 9.2x1016/cm3,33.82cm2V-1s-1, respectively. The single ZnO nanorods also showed high sensitivity to the UV light (325nm). Under the UV illumination, the UV induced current increase nearly 10 times than the dark current. In addition, the nanorods also exhibited a slow UV response due to the effects of the oxygen ions on the surface of the nanorods.
Dicing Laminated Wafer for QFN 3D Stacked Die Packaging
Authors: Abdullah Shahrum , Endut Z. , Ahmad I. , Jalar Azman , Yusof Suhaila M.
Published: March 2009

Nowadays, die attach film (DAF) gaining popularity in microelectronic packaging as
integral part in facilitating the growth of wafer level packaging and stacked die packaging. DAF
applied to the backside of wafers prior to saw have many advantages, such as the elimination of the
epoxy dispensed process step and the reduction of epoxy related failure mode. However, the dicing
process for DAF wafer usually associated with sidewall chipping, DAF whiskering and crack that
will affect reliability of Quad Flat Non-Leaded (QFN) stacked die. Blade properties and
characteristics are the crucial factor in analyzing the DAF dicing results. In this paper, we evaluate
the blade characteristics before and after DAF wafer dicing process for our stacked die packaging.
The qualitative measure by means of the Scanning Electron Microscope (SEM) and Energy
Dispersive X-Ray (EDX) analysis were performed in order to understand the lamination and dulling
effect on blade surface. The obtained results showed that sawing polymeric material such as wafer
laminated with DAF induces lamination of polymeric material onto the blade surface and reduce
blade cutting edge. As a result, reduce the quality of DAF dicing process.
Nano Size Lanthanum Doped Semiconductors: Synthesis, Characterization and their Photocatalytic Activity
Authors: Anandan S. , Ikuma Y. , Kudoh T. , Ogita Y. , Murugesan V.
Published: March 2009

In the present study, La-doped TiO2 and ZnO nano particles were synthesized and
extensively characterized by various sophisticated techniques such as XRD, nitrogen adsorption,
UV-Vis, AFM and XPS. Rough and highly porous surface of La-doped photocatalysts was
observed by AFM, which is critical for enhancing the photocatalytic activity. Degradation and
mineralization studies of monocrotophos (MCP) revealed that 1 wt% La-doped TiO2/ZnO exhibits
high activity compared to that of pure TiO2/ZnO.
MOVPE Growth Window for High-Nitrogen GaAsN Alloy Films for Long Wavelength Emission
Authors: Sanorpim S. , Nakajima F. , Katayama R. , Onabe Kentaro
Published: March 2009

The high quality GaAsN epitaxial films with the typical thickness of 150-200 nm and the N
contents up to 5.5% were grown by MOVPE. The maximum N content of 2.75% at the growth
temperature of 550 oC was enhanced to 5.1% at 500 oC and 5.5% at 450 oC. The lower growth
temperature may efficiently suppress desorption of N atoms from the growing surface. The narrow
high-resolution X-ray diffraction peaks and the clear Pendellösung fringes indicate that the GaAsN
films with high uniformity and fairly flat interface were obtained. The 6K-photoluminescence (PL)
peak energy of the GaAsN films was varied from 1.38 eV to 1.01 eV with increasing N content up to
2.75%, but no near-band-edge emission was observed in the higher-N-content films, indicating the
increase of nonradiative recombination centers caused by the N-related lattice imperfections. Besides,
after post growth thermal annealing at 650 oC for 2 min, PL spectrum shows that the near-band-edge
emission as low as 0.97 eV (1.3 μm) have been achieved with the film of 5.1% N.
Optical Transitions in InGaPN/GaP Single Quantum Wells on GaP(100) Substrates by MOVPE
Authors: Sanorpim S. , Kaewket D. , Tungasmita Sukkaneste , Katayama R. , Onabe Kentaro
Published: March 2009

Optical transitions in the In0.050Ga0.950P0.975N0.025/GaP lattice-matched single quantum
wells (SQWs) with different well widths (LZ = 1.6 - 6.4 nm) have been investigated by
low-temperature photoluminescence (PL) and PL-excitation (PLE). PL spectra showed the strong
visible emission from the samples which attracted to a variety of optoelectronic device applications
such as light emitting and laser diodes. Comparing to the bulk film, the PL peak position and the
fundamental absorption edge of PLE spectra exhibit blue-shift, which is corresponded to the quantum
confinement effect by the well. Comparison between the absorption edge of PLE spectra and the finite
square well calculation demonstrate that the effective bandgap energy of the InGaPN/GaP system is
might be originated mainly from the N-related localized states.