bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Characterization of Hydroxyapatite-Based, Organic-Inorganic Composites
Authors: Rivera-Muñoz Eric M. , Velázquez-Castillo Rodrigo , Muñoz-Alvarez P.
Published: March 2009

Hydroxyapatite-based materials have been used for dental and biomedical applications.
Newly developed synthesis techniques give cause to a broad field in the study of these materials and
industry demands products with better properties day by day. The purpose of the present work was
to evaluate the mechanical properties of hydroxyapatite-based (HAp-based), organic-inorganic
composites.
HAp-based, organic-inorganic composites were obtained by modified gel casting process and
organic molecules in a gelatin solution.
HAp samples of different sizes and shapes were obtained with controlled micro and macro porosity
and then were immersed into several gelatin solutions with different concentrations.
X-ray powder Diffraction (XRD), Infra Red (IR) Spectroscopy and Scanning Electron Microscopy
(SEM) techniques were used to analyze samples before and after gel casting process in order to
assure that chemical and physical properties remains the same after this process. IR Spectroscopy
and SEM techniques were used to characterize samples after the introduction of organic phase in
order to analyze the final morphology of samples. Mechanical characterization was made in
compression mode to samples without and with different concentrations of organic phase in order to
establish the optimum conditions in which the highest compressive strength and Young’s modulus
is reached.
Spontaneous and Biomimetic Apatite Formation on Pure Magnesium
Authors: Cortés-Hernández Dora A. , López Haydée Y. , Mantovani Diego
Published: March 2009

In order to decrease its degradation rate, pure magnesium was subjected to the following
treatments: (1) heat treatment at 345oC for 15 min and (2) heat treatment at 380°C for 30 min
followed by hot rolling at 350°C. The treated samples and non-treated controls were immersed in
simulated body fluid (SBF) at 37oC for different periods of time. In all cases, the magnesium
released into the SBF, the weight loss of the specimens and the pH of SBF increased with time of
immersion. The hot-rolled samples showed a lower degradation rate and lower pH values. A lower
increase of magnesium concentration in the SBF corresponding to the hot-rolled samples was also
observed. The main and unexpected positive finding of this work was that in all cases, a layer of Ca,
P-rich was formed on the substrates after only 3 days of immersion in SBF. This indicates that
metallic magnesium is a potential bioactive material. In the aim to promote the formation of a
thicker bioactive layer than the one observed on the samples immersed in single SBF, hot-rolled
magnesium was biomimetically-treated using wollastonite ceramics, SBF and a more concentrated
solution (1.5 SBF). A homogeneous and dense bone-like apatite layer was observed on the
biomimetically-treated samples.
Microstructures and Mechanical Properties of Biologically-Inspired Ti-Nb Based Alloys with Ternary Element Additions
Authors: Kim Han Sol , Kim Won Yong
Published: March 2009

Microstructures and mechanical properties including elastic modulus were investigated in
terms of ternary alloying elements Si addition, Nb content variations and tensile test. Martensite
structure with α'(hcp) or α"(orthorhombic) was observed in Ti-xNb-1.5at.%Si, where x=10-20at.%.
The crystal structure of martensite formed from water quenching process was largely dependent upon
Nb content but does not on Si content. On the basis of experimental results obtained, it is suggested
that Si has an effective role to suppress the precipitation of ω phase leading to reduction in elastic
modulus in the metastable β phase region. Metastable β phase region was superior to reduce the
elastic modulus than stable β phase region in the present alloy system. The minimum value of elastic
modulus was measured to 48GPa. We have found that stress-induced martensitic transformation
takes place during the deformation in the present alloys. Within the alloys having β(bcc) phase
studied Nb-poor region appeared to exhibit a dominant behavior for stress-induced martensitic
transformation than Nb-rich region. This result suggests that metastable β phase is superior to stable β
phase for the occurrence of stress-induced martensitic transformation in the present alloy system.
Fretting Fatigue Studies of Surface Modified Biomedical Titanium Alloys
Authors: Vadiraj Aravind , Muthuswamy Kamaraj
Published: March 2009

Fretting fatigue is a form of adhesive wear damage caused due to tangential micro motion of
two contact bodies under normal pressure and cyclic load. Biomedical implants such as hip joints
and bone plates undergo fretting fatigue damage leading to premature in-vivo failure and revision
surgeries. Surface modification of implants delays the process of fretting and thereby improves the
life of these medical devices. This work involves investigation of fretting fatigue damage of surface
treated titanium alloys couple. The surface treatment involves PVD TiN coating, Plasma nitriding,
Ion Implantation, Laser nitriding and thermal oxidation. Fretting of all surface treated alloys have
shown both adhesive and abrasive mode of contact damage. Friction coefficient of all the surface
treated pairs is less compared to uncoated alloys. Plasma nitrided pairs have shown the best
performance in terms of fretting fatigue life and friction coefficient compared to all other coatings.
Ion implanted pairs have shown little improvement in fretting fatigue lives due to shallow modified
layer. PVD TiN coated pairs have irregular friction pattern due to abrasive particles at contact.
Thermal oxidation and Laser nitriding have shown poor fretting fatigue performance due to high
case thickness.
Low Pressure Infiltration of Molten Aluminum Alloy to Metal Fiber Preform
Authors: Sasaki Gen , Choi Yong Bum , Matsugi Kazuhiro , Sorita Naoki , Kondoh Shunsaku , Yanagisawa Osamu
Published: March 2009

In order to fabricate the metal matrix composites by low-pressure infiltration by gravity
casting machine, the preform made from FeCrSi fiber with 40μm and matrix of A336.0 aluminum
alloy was used. The volume fraction of fiber in preform was about 20%. The temperatures of die,
preform and molten alloy were 200 oC, 400 oC and 750 oC, respectively. By controlling the
infiltration of molten aluminum alloy to one direction by using barrier plate, the quantity of pores
caused by curling of air degrades dramatically. Molten aluminum alloy was able to infiltrate at low
pressure of 0.2MPa. As increasing the pressure, porosity in composites decreased. The composite
with no pores was obtained by barrier plate and 0.8 MPa of molten alloy pressure. This composite
had high strength at high temperature of 200-400oC.
Reducing Threshold Pressure for Infiltration of Al-12Si Alloys into Carbon Particle Compacts by Placing a Thin Layer of Sn at the Infiltration Front
Authors: Rodríguez-Guerrero Alejandro , Narciso Javier , Louis Enrique , Rodríguez-Reinoso F.
Published: March 2009

The oxide layer that usually covers the surface of liquid aluminum and its alloys, is one
of the main factors that hinders infiltration of these alloys into graphite particle compacts. The
oxide film increases the threshold pressure for infiltration and the porosity of the resulting
composites is large because the wetting at the metal/carbon interface is reduced. Infiltrating
graphite compacts with tin requires, however, a much lower pressure, less than half of that required
to infiltrate the eutectic Al-12Si alloy. As the surface tension of tin is half that of the Al-12Si alloy,
this result indicates that wetting at the Sn/C interface is slightly better. As a result, porosity in the
infiltrated samples is reduced. In order to reduce the threshold pressure and improve the properties
of Al-Si/graphite composites, a novel method has been used in this work that consists in placing a
thin film of tin at the compact end through which infiltration takes place. During the infiltration
process the graphite particles are firstly infiltrated by tin, which is pushed by the aluminum alloy,
thus avoiding the oxidation of the latter. The method proved to be very effective in reducing the
threshold pressure, while keeping almost constant the infiltration rate.
Microstructural Evolution in the Processing of Bulk Samples Using High-Pressure Torsion
Authors: Horita Z. , Langdon Terence G.
Published: March 2009

Although high-pressure torsion (HPT) is now a well-established technique for imposing
severe plastic deformation on metallic materials, the technique is generally restricted to use with
thin disk samples. This paper describes experiments which were conducted to evaluate the
potential for making use of HPT with bulk samples in the form of small cylinders. The
experiments were performed using an Al-Mg-Sc alloy and the samples were strained under a
pressure of 1 GPa at room temperature. The results demonstrate excellent microstructural
refinement in the vicinity of the central zone around the periphery of the cylinders.
Development of High Strength Mo2NiB2 Ternary Boride Base Cermets Produced by Reaction Boronizing Sintering
Authors: Takagi Kenichi , Yamasaki Yuji , Hirata Koro
Published: March 2009

The effects of V substitution for Cr to the sintering behavior of Cr containing Mo2NiB2
ternary boride base cermets and Mn addition to the mechanical properties and microstructure of the
Cr and V containing cermets were investigated by using Ni-5.0B-51.0Mo-(17.5-x)Cr-xV (mass%)
and Ni-5.0B-51.0Mo-12.5Cr-5.0V-(0-1.5)Mn (mass%) model cermets.
10mass%V substitution for Cr in the Cr containing cermets markedly improved transverse
rupture strength and hardness from 2.27 to 2.94GPa and from 85.3 to 87.2RA respectively and
refined the microstructure by retarding the progress of sintering especially at liquid phase sintering
stage. Small amount of Mn addition to the Cr and V containing Mo2NiB2 base cermets
significantly improved the sinterability and increased the mechanical properties of the cermets.
Microstructure and Texture of Zirconium and Titanium Grain Refined by Equal Channel Angular Pressing
Authors: Yu Seng Ho , Shin Dong Hyuk , Hwang Sun Keun
Published: March 2009

Zr702 and commercial purity Ti were grain refined through severe plastic deformation
and their microstructure and texture characteristics were studied by optical microscopy,
transmission electron microscopy, X-ray diffraction and electron back-scattered diffraction. The
equal channel angular pressing was conducted at 350°C using a 90°/20° die. Up to 8 passes of
pressing were performed via three different routes, A, C and BC, which resulted in reduction of the
grain size down to 0.2-0.5.m. The two materials showed similar evolution characteristics of
microstructure and texture. While the specimens pressed via route A showed lamellar grain shapes
those via route C or BC exhibited equiaxed grains. A split basal texture was developed in the
microstructure obtained by the route A pressing, which was similar to the cold rolling texture,
whereas an asymmetric texture was produced in the specimens pressed via route BC. In the case of
route C pressing, the texture characteristics were closer to those of the route BC case.
Fabrication and Corrosion Properties of Iron Aluminum Alloy/Steel Laminated Composite Prepared by Clad Rolling
Authors: Masahashi Naoya , Oku M. , Watanabe Sadao , Hanada Shuji
Published: March 2009

The laminated composite of Fe–Al alloy and CrMo steel was fabricated by clad rolling to
provide additional properties to the steel such as corrosion resistance, strength, and light weight.
Three layered composite consisting of alloy/steel/alloy was succesfully fabricated using the process
condition to satisfy the criteria for simultaneous deformation of different materials. The fabricated
composite could be cold rolled to 120 μm thickness (99.8 % reduction), and wound to a coil without
damage. The corrosion resistance of the composite in a sulfuric acid solution was comparable to
that of monolithic CrMo steel, and it depends on the aluminium content of the Fe–Al alloy. The
aluminium content dependence of the corrosion behavior is explained by the corrosion potential
(Ecorr) of the Fe–Al alloy derived from the polarization curves in the solution. In order to improve
the corrosion resistance of the composite, pre-oxidation treatment was conducted to form Al2O3
layer to protect the substrate. Analyses by XPS and SIMS show that the Al2O3 oxide fraction
increases with the oxidization temperature and Al content of the alloy. The pre-oxidation treatment
improved the corrosion resistance of the composite in a sulfuric acid solution. It is concluded that
the effect of oxidation on the corrosion resistance is due to the formation of Al2O3 oxide and the
Al2O3 fraction in the oxides.
Wettability of Basal and Prismatic Plane of Graphite by Molten Aluminum-Magnesium Alloy
Authors: Yoshida M. , Matsunaga T. , Ogata K. , Hatayama T. , Shinozaki K.
Published: March 2009

In order to estimate work of external force per unit area to infiltrate molten aluminum
into bundle of two types of carbon fibers which were PAN (polyacrylonitrile) based and pitch based,
wettability of graphite by molten pure aluminum and aluminum – 2.0, 2.9 and 9.1 mass %
magnesium alloy was measured using sessile drop method. Basal plane and prismatic plane exist on
the surface in the case of PAN and pitch based fibers, respectively. The wettability was examined in
the atmosphere of Ar + 3 vol. % H2 at 1189 K. Both the contact angle and the surface tension were
estimated using Young-Laplace equation. The surface tension decreased form 1.0 N/m at 0 mass %
Mg to 0.7 mass % Mg at 9.1 mass % Mg. The contact angle between molten aluminum and basal
plane or prismatic plane of graphite was 127º or 148º respectively. In the case of basal plane, the
contact angle increased with increasing magnesium content. In the case of prismatic plane, whereas,
the contact angle decreased from 155º at 2.0 mass % Mg to 125º at 2.9 mass % Mg. The work of
external force for infiltration was calculated using Young’s equation. In the case of basal plane, the
work was constant at 0.6 J/m2 regardless of magnesium content. In the case of prismatic plane, the
work decreased with increasing magnesium content. It was found that the influence of magnesium
content on the work would be different between using PAN-based carbon fiber and using
pitch-based carbon fiber.
Study of Environmental Corrosion Behavior and Mechanism of the Carbon/Epoxy Composite
Authors: Li Xiao Fei , Zhang Qi , Xu Jun Hua
Published: March 2009

Polymer composite materials, as advanced materials have been widely used worldwide,
especially in the advanced technology field, due to their outstanding properties. Nowadays, a growing
attention has been paid to the environmental corrosion failure of composites. Since it is environment
related corrosion, the test parameters selected were temperature, humidity and ultraviolet. Among all
the environmental factors, the temperature, especially acts with humidity, is the most affective factor.
In order to get detailed information, the weight gains of the samples tested were measured regularly
during the test. By the comparison, it can be seen that the water absorption rate had been affected
remarkably due to the salt existence or the temperature change. The observation of the sample
microstructure showed that there were many holes on the surface, indicating that the surface of the
samples was destroyed by the test, and that there were some interactions between the surface layer
and the absorbed component. It is that only the effect of temperature and humidity was discussed in
this paper, the effect of the rest environmental factors will be discussed in following paper.
Synthesis and Characterization of Exfoliated Natural Mica/Polymer Nanocomposites
Authors: Tamura Kenji , Uno Hikaru , Yamada Hirohisa
Published: March 2009

The effect of natural mica on the morphology and properties of polyamide 6 (PA-6)
nanocomposites was examined. Natural mica (sericite) acquired from a well-known mine in
Shimane, Japan was ion-exchanged with an alkyl amine hydrochloride compound. The resulting
organomica was extruded with PA-6 using a twin-screw extruder. Quantitative analysis of TEM
photomicrographs of the nanocomposite reveal a fairly large average particle length and a higher
degree of platelet exfoliation for the natural mica-based nanocomposite compared to the clay
version, thus translating into a higher particle aspect ratio. The resulting nanomica/PA-6
composite exhibits a high degree of mica exfoliation and improved thermal mechanical properties.
In-Situ Gold Nanoparticle Generation Using a Small-Sized Ceramic Heater with a Local Heating Area
Authors: Jung Jae Hee , Oh Hyun Cheol , Ji Jun Ho , Kim Sang Soo
Published: March 2009

A generation method of in-situ gold nanoparticles using a small-sized ceramic heater
with a local heating area is presented. The heater surface temperature was maintained uniformly.
Gold nanoparticles with high concentration (> 107 particles/cm3) were produced and were stably
generated for several hours because the heater surface temperature was maintained uniformly.
Higher surface temperature yielded higher geometric mean diameter (GMD), geometric standard
deviation (GSD), and total number concentration. Using this generator particle size distribution was
easily controlled. Spherical and non-agglomerated nanoparticles were observed from TEM images,
even at high concentration and high temperature. Although air was used as a carrier gas, the
generated gold nanoparticles displayed pure crystallinity of the gold element, as determined by
XRD analysis.
Photocatalytic Activity of Doped NaTaO3 and NaNbO3 : (Y, La, Nd, Sm) Sol Gel on Degradation of Rhodamine B by UV Irradiation
Authors: Torres-Martínez Leticia M. , Garza-Tovar Lorena L. , Meza-de la Rosa M. Elena , Martínez-de la Cruz A. , Cruz-López Arquímedes
Published: March 2009

The catalytic photodegradation of Rhodamine B with UV irradiation over NaMO3
(M= Ta and Nb) doped with Y2O3, La2O3, Nd2O3 and Sm2O3 has been studied in our
laboratories. All catalysts were characterized by different techniques such as X-ray powder
diffraction (XRD) and thermal analysis (DTA/TGA). Surface characterization of the solids was
carried out from adsorption isotherms and infrared spectroscopy (FTIR). The band gap energy
(Eg) of materials ranged from 4.1 to 2.9 eV. For comparative purpose the materials studied as
catalysts were also synthesized by classical solid state reaction.
Properties of Sol-Gel Coating Film Synthesized from Nano Boehmite and Methyltrimethoxysilane
Authors: Myung In Hye , Ahn Myeong Sang , Kang Dong Pil
Published: March 2009

Several sol solutions were synthesized by using two kinds of nanosized boehmite and
methyltrimethoxysilane (MTMS) according to the changing amount of MTMS at different reaction
time. To understand their physical and chemical properties, sol-gel coating films were fabricated on
glass. The sol solutions were prepared from boehmite of spherical shape (boehmite1)/MTMS and
mixed boehmites of spherical and fibrous shapes (boehmite2)/MTMS. The soluble stability of
boehmite1/MTMS was observed in the sol solution left for 24 h, however, that of boehmite2/MTMS
was observed in the sol solution left for 48 h. The contact angle of sol-gel coating films from
boehmite/MTMS increased with MTMS contents and reaction time. The films formed a flat surface
with the increasing MTMS contents and decreasing reaction time. The electrical resistivity of films
increased with MTMS contents. The thermal degradation of films occurred at approximately 400 oC.
Synthesis and Characterization of Multi-Sulfonated Poly(Aryl Ether Ketone)s Proton Exchange Membranes
Authors: Lee Dong Hoon , Park Hye Suk , Seo Dong Wan , Hong Tae Whan , Kim Whan Gi
Published: March 2009

A series of sulfonated poly(aryl ether ketone)s were prepared by condensation
polymerization with bisphenol A and 1,2-bis(4-fluorobenzoyl)-3,6-diphenylbenzene, and followed
by sufonation with chlorosulfonic acid. The polymers were characterized by Fourier transform
infra-red (FTIR) and ion exchange capacity (IEC) to verify sulfonation. Differential scanning
calorimetry (DSC) and thermogravimetric analysis (TGA) were carried out to investigate the
thermal stability of the prepared membranes. The membranes were found to possess all the requisite
properties; Ion exchange capacity (3.31meq./g), glass transition temperatures (207-230°C), and low
affinity towards methanol (2.04x10-6-4.15x10-7 cm2/S).
Preparation of Mesostructured Carbon (MSC) for Removal of Natural Organic Matter (NOM) in Aqueous Solution
Authors: Jung Hae Ryong , Seo Sang Deok , Choi Hee Chul
Published: March 2009

Mesostructured carbon (MSC) has been synthesized by the carbonization of assynthesized
mesocellular siliceous foam (MCF)/P123 nanocomposite followed by the dissolution of
the silica using 10 wt.% HF solution. SEM, TEM, and BET instruments were used to characterize
the mesostructured carbon. Batch experiments were performed to evaluate its ability to adsorb
natural organic matter (NOM) in various pH levels. MSC showed enhanced adsorption capacity for
NOM than the commercial activated carbons. MSC possessed approximately 3.3 and 2.2 times
greater the solid-water partitioning coefficient of NOM, Kd, at pH 7 than coal-based and coconutbased
activated carbons, respectively. This increased Kd of MSC resulted from mesoporous
structures in the range of 4-6 nm on the surface. The Kd value decreased with increasing initial pH
levels, which is considered to be due to ionization of functional groups of NOM.
Removal of Heavy Metal Ions from Aqueous Solution by Manganese Dioxide-Coated Polypropylene Granules: An Implication of Rainwater Runoff Treatment
Authors: Mavlyankariev Sardor Abdukakharovich , Rhee Dong Seok
Published: March 2009

Modified polypropylene granules (MDPG) were coated by manganese dioxide and their
surface and adsorptive characteristics were studied. Surface characteristics of the adsorbent were
investigated by B.E.T. surface area and mercury porosimetry. Coating has significantly increased
the surface area of granules from 0.12 m 2 /g B.E.T. N 2 to 15.42 m 2 /g. Gas pycnometry
measurements resulted in low density of 0.13 g/cm 3 for uncoated granules, the fact ascribed to 0.65
porosity measured. Coating increased micro pore volume of raw granules by a factor of 58.
Adsorption experiments were conducted in column flow-through reactors at pH 6.0 and 10 g/L
sorbent dosage for mixture of four metal species, each having 5 mg/L initial concentration. More
than 60 % of Pb and Cu was removed within first 20 min, whereas just over 29 and 13 % for Cd and
Zn respectively. Furthermore, more than 99, 84, 40, 16 % of Pb, Cu, Cd, and Zn was removed
within 1 h. Adsorption efficiencies for 5 ppm of initial metal concentration at pH 5.0 and 10 g/L
sorbent/solute ratio resulted in 4.9, 3.9 mg of Pb and Cu sorbed per gram of sorbent. And these
ratios for separate metal ions were substantially higher than those for the mixture of the four metal
ions. For 5 g/L of sorbent under the same parameters, removal efficiencies of Cd and Zn were
respectively 0.98, 0.75 mg/g, correlating well with Freundlich adsorption model. Adsorption
kinetics showed relatively fast removal rates within first 5 h of sorption. Desorption resulted in
eluting 57, 70, 76, 78 % of the initial feeding concentrations for Pb, Cu, Cd, Zn, respectively.
Axial Compression and Bending Characteristics of CFRP Hat Shaped Member According to Orientation Angle
Authors: Kim Ji Hoon , Lee Kil Sung , Yang In Young
Published: March 2009

The strength members, such as front-end side members, are subjected to axial compressive
and bending load during collision. Therefore, it is important to consider energy absorption by the axial
compression and the bending for design of effective strength members. And at the same time, it also
should consider reducing weight of the members. In this study, CFRP (Carbon Fiber Reinforced
Plastics) side members with single-hat-section shape were manufactured. The axial compression and
the bending tests were performed for the members using universal testing machine, and the axial
compression and the bending characteristics were analyzed. Stacking condition related to the energy
absorption of composite materials is being considered as an issue for the structural efficiency. So the
energy absorption of the member under the axial compressive load and the bending load were
experimentally investigated.
Effects of Isothermal Heating Process and Rare Earth Elements Addition on the Mechanical Properties of Semi-Solid Formed Mg-5%Zn Alloys
Authors: Kim Jeong Min , Jun Joong Hwan , Kim Ki Tae , Jung Woon Jae
Published: March 2009

Two-step isothermal heating and conventional one-step heating processes were used to
produce the semi-solid slurry of Mg-5%Zn-0.5%Zr alloys with and without 1%RE. It was found
that the slurry with better semi-solid characteristics could be fabricated by the two-step heating
compared to the conventional process. Only the small amount of RE addition to the Mg-5%Zn-
0.5%Zr alloy was observed to reduce the solid particle size of slurry significantly and to improve
the tensile strength at 150oC, probably owing to Mg-Zn-RE phase with a high thermal stability.
Electromagnetic Properties of Bi System Superconductor
Authors: Lee Sang Heon
Published: March 2009

Effects of Ag2O doping on the electromagnetic properties in the BiSrCaCuO superconductors.
The electromagnetic properties of Ag2O doped and undoped BiSrCaCuO superconductor were evaluated to
investigate the contribution of the pinning centers to the magnetic effect. It was confirmed experimentally
that a large amount of magnetic flux was trapped in the Ag2O doped sample than that in the undoped one,
indicating that the pinning centers of magnetic flux are related closely to the occurrence of the magnetic
effect. It is considered that the area where normal conduction takes place increases by adding Ag2O and the
magnetic flux penetrating through the sample increases. The results suggested that Ag acts to increase
pinning centers of magnetic flux, contributing to the occurrence of the electromagnetic properties.
Evaluation of Indentation Test for Measuring Young’s Modulus of Cancellous Bone
Authors: Lee Moon Kyu , Choi Kui Won , Lee Tae Soo , Lim H.N.
Published: March 2009

The indentation test has been in the spotlight due to easy and non-destructive testing
characteristics. However, there are little studies for the indentation test of porous materials in the
evaluation aspect of methodology. The goal of this study was to evaluate a spherical indentation test
in the aspect of indenter-size and indentation depth by measuring elastic modulus of porous
materials such as a cancellous bone using a FEM. We developed a microstructure-based FE model
of cancellous bone with apparent density 0.2~0.8 g/cm3 in order to simulate uniaxial compression
test and indentation test in the light of anatomical observation with a scanning electron microscope
(SEM). We obtained a load-displacement curve through the indentation simulation and calculated
the Young’s modulus of cancellous structure based on Pharr's hypothesis. The result indicated that
indenter diameter has to be more than five times of pore size and indentation depth should be about
8% of indenter diameter at least to obtain the appropriate result of the indentation test. It is expected
that this result may guide to the design and the simulation of indentation test for porous materials
Evolution of Al Alloy Melt Foam Pore Structure in Foaming Process
Authors: Yang Dong Hui , Seo Chang Hwan , Yao Da Peng , Hur Bo Young
Published: March 2009

A study was carried out to understand the relationship between the pore structure’s evolution of
Al alloy melt foam and its preparation variables, which include decomposition properties of titanium
hydride, the stirring foaming time and the holding foaming time. The results show that the foaming process
of Al alloy melt can be inferred by the relation curves of decomposition quantity of titanium hydride and
time at a specific temperature. The porosity of Al alloy melt during stirring foaming period is kept constant
while the pore number increases and pore diameter decreases, which is a new method of fabricating Al alloy
foam with a relatively low porosity and small pore size.
Formation of Boride Eutectic with Addition of Boron in Mod. 12Cr-1Mo Steels
Authors: Choi G.S. , Kim Y.H. , Kang S.S. , Jung Yeon-Gil , Lee J.H. , Rye S.H.
Published: March 2009

The behavior of boride formation has been examined with solidification rates and boron
contents by observing the solid/liquid interface using directional solidification in Mod. 12Cr-1Mo
alloys. The phase transformation temperatures of liquidus, solidus, eutectic formation, and final
solidification were analyzed by DTA. In order to analyze the crystallographic structure of the boride,
extractive method, extracting the boride from the matrix, was used. The boride was proved as M3B2,
and this boride phase expected to be formed by eutectic reaction. It has been also found that the boride
formation depends on contents of born as well as the other alloying elements, such as C and W. As
increasing boron contents, the amount of boride eutectic increased. Also, the alloying element W was
shown to enhance the formation of the boride.
Hertzian Indentation Damage Behavior of Highly Porous Silicon Nitrides
Authors: Zeng Hong , Wang Hong Jie , Lin Dan Bo , Bai Yu , Qiao Guan Jun , Gao Ji Qiang
Published: March 2009

Highly porous Si3N4 ceramics in service are usually subjected to continuous impact of
solid particles which may give rise to localized damage and consequently to strength degradation.
Hertzian indentation and three-point bending tests were conducted to investigate the contact damage
behavior of highly porous Si3N4 ceramics in this paper. The Hertzian indentation damage
morphologies were examined by using a bonded-interface technique. As a result of intragranular
microfracture under Hertzian indentation, a distributed subsurface damage region is developed
beneath the indenter. It was shown that, with increasing indentation load, the damage region
extends progressively and a quasi-plastic stress-strain response exhibits. Failure sources were
observed to be Hertzian indentation sites in three-point bending tests, leading to a gradual strength
degradation.
High Temperature Corrosion of Ti3AlC2 in Ar-1%SO2 Atmosphere
Authors: Lee Dong Bok , Choi Jee Hoon
Published: March 2009

The layered, machinable ternary compound, Ti3AlC2, was corrosion-tested at
800, 900, and 1000oC under an Ar-1% SO2 gas atmosphere. The scale formed consisted
primarily of TiO2 and α-Al2O3. As the corrosion progressed, the scale became thicker
and developed into an outer TiO2 layer and an inner (TiO2,Al2O3)-mixed layer.
Hollow Amorphous Formation via Oxidation of Al Nanoparticles at Low Temperatures
Authors: Nakamura Ryusuke , Lee Jung Goo , Tokozakura Daisuke , Mori Hirotaro , Nakajima Hideo
Published: March 2009

Formation of hollow structure through oxidation of Al nanoparticles was studied by
applying transmission electron microscopy. Al nanoparticles 6~8 nm in diameter were observed to
become hollow particles after having been exposed to air at 295 K for a few minutes. An analysis of
the Debye-Sherrer rings in the selected area diffraction patterns before and after oxidation showed
that hollow oxide nanoparticles are amorphous. The formation mechanisms of hollow oxide are
discussed based on the low-temperature oxidation mechanism of Al and on the comparison with our
previous results of hollow ZnO formation via oxidation of Zn nanoparticles.
Influence of Particles on Cell Structure of Al-Mg Alloys Foamed by Melt Foaming Method
Authors: Park Soo Han , Seong Hwan Goo , Song Yeong Hwan , Seo Chang Hwan , Zulkifli Zulkifli , Hur Bo Young
Published: March 2009

Al-Mg alloy foams containing different Mg contents were synthesized via a conventional
melt foaming method. The surface structures of pores formed in resultant foamed alloys was
characterized by scanning electron microscopy and x-ray diffractometer. It was found that the pore
structures were deteriorated with increasing Mg contents, while the percent porosities did not vary
with increasing Mg contents, about 90% and 3~5 mm in pore size. The detailed microstructural
examination conducted on increasing Mg containing alloy foams revealed presence of various oxide
particles on the surface of individual cells, including MgAl2O4 particles in a form of fine spinel; its
small amount for Al-1wt%Mg alloy foam but relative high amount of Al-4wt%Mg one. This
suggested the negative effect of MgAl2O4 on the stable pore and thus cell structures in corresponding
alloy foams. The possible mechanism associated with MgAl2O4 formation was discussed in the
present study.
Influence of Process Parameters on the Adhesive Strength of CrN Coatings
Authors: Jeong G.C. , Kim Il Ho , Kwun S.I.
Published: March 2009

In order to enhance the corrosion and wear resistance of the STVAX alloy, the CrN film
has been deposited by UBM(unbalanced magnetron) sputtering. In this study, the influence of
process parameters, such as N2 gas concentration and Cr interlayer insertion, on the adhesive
strength was investigated. By increasing the concentration of N2 gas from 30% to 33%, the
microstructure of the coating layer was changed from hexagonal Cr2N to cubic CrN. By increasing
N2 gas concentration to 38%, a CrN coating layer with a preferred orientation of <111> plane was
formed. Nanoindentation testing showed that the mechanical properties of coatings varied according
to the coating type and crystallographic orientation. Superior adhesive strength was obtained at the
of N2 gas concentration of 38%, and higher hardness at 33% concentration. The adhesive strength
of the coating film was higher with a Cr interlayer than that without. These findings showed that the
Cr interlayer between the CrN coating and the STAVAX substrate significantly improved the
adhesive strength of coating to the substrate.
Influence of Reheating Profile on Microstructural Evolution of 2024 Al Wrought Alloy for Thixoextrusion
Authors: Jang Dong In , Yoon Young Ok , Jo Hyung Ho , Kim Shae K.
Published: March 2009

Thixoextrusion, one of the thixoforming processes, has advantages of high productivity,
reduction of the extrusion pressure and cost saving because of the low energy consumption
compared with the conventional extrusion processes. For the thixoextrusion, the low liquid fraction
(fL<0.3) should be achieved and also the liquid fraction and average grain size should be uniform
according to the reheating profile at the desired low liquid fraction. The main emphasis of this study
is to investigate the feasibility of thixoextrusion for 2024 Al wrought alloy without additional
pretreatment. The results show that the liquid fraction and average grain size were almost uniform
with respect to isothermal holding temperature and time. It was very useful for thixoextrusion in
terms of process control such as billet temperature control and actual extrusion time.
Microstructure Analysis and Characterization of Li(Ni1-xCox)O2 Thin Film Prepared by Li Diffusion on Ni-Co Alloy Substrates for Cathode Application
Authors: Tak Jin Sung , Chung Jun Ki , Kim Sang Suk , Lee Sung Gap , Kim Cheol Jin
Published: March 2009

The currently commercialized cathode material for Li ion batteries such as LiCoO2
exhibited limit to further improve the performance of the batteries, since the employed screen printing
method for cathode fabrication is difficult to reduce the thickness and control the microstructure of
the oxide layer. In this studies, we have synthesized Li(Ni1-xCox)O2 thin film by utilizing Li-diffusion
reaction on the surface of Ni-Co alloy substrates. For the preparation of Ni-Co alloy rod, Ni and
20at.%Co powder were mixed for 24hrs by ball milling, and then pressed into rod-shape by
cold-isostatic pressing. The Ni-Co rods were sintered at 1100°C for 6hrs in the reducing atmosphere
of Ar 96% and H2 4%. The sintered Ni-20at%Co rod was cold-rolled into tape at 5% reduction ratio
with the final thickness of 100㎛, and the recrystallization heat treatment for the development of the
cube texture of the rolled Ni alloy tape was carried out at 1000°C in Ar 96% and H2 4%. After thin
layer of metallic Li was deposited on the surface of Ni-Co template using thermal evaporation method
in the glove box, the Li/Ni-Co composite tape were heat-treated at 700~850°C for 1~2hrs in oxidizing
atmosphere to induce Li-diffusion into Ni-Co substrate and Li(Ni0.8Co0.2)O2 phase formation. The
phase evolution of Li(Ni0.8Co0.2)O2 was confirmed by X-ray diffraction and the grain size and
morphology of the surface were analyzed by scanning electron microscopy and atomic force
microscopy. Also the charge and discharge test were conducted to confirm the electrical
characteristics of Li(Ni1-xCox)O2/Ni-Co thin film for the cathode application.
Noncombustible Magnesium Alloy Processed by Rotary-Die Equal Channel Angular Pressing Method
Authors: Watazu Akira , Shigematsu Ichinori , Huang Xin Sheng , Suzuki Kazutaka , Saito Naobumi
Published: March 2009

Noncombustible Mg-8Al-2Ca rods were processed by RD-ECAP. The magnesium alloy
rod had Mg matrix and Al2Ca second phase. Grains with about 20 μm in diameter were observed in
the matrix of the raw materials. The grains in matrix had no anisotropy. On the other hand, positions
of second phase particles had anisotropy and the second phase particles formed lines. The samples
processed by RD-ECAP had no crack and the samples had 20mm diameter. Grains in matrix of the 4
pass RD-ECAP sample had no anisotropy and the grains had under about 5 μm in diameter. The
second phase particles had round shapes and were uniformly distributed as compared with the raw
material rod. Therefore, the RD-ECAP is useful for forming noncombustible Mg-8Al-2Ca alloy with
fine-grains.
Design of Rotational Particle Structure with Negative Poisson’s Ratio Using Numerical Method
Authors: Lee Moon Kyu , Choi Jae Bong , Choi Kui Won , Lim H.N.
Published: March 2009

In the area of biomaterials, the structures with negative Poisson’s ratio are able to be
applied to the polymer component of prosthesis, artificial blood-vessel and catheter. To induce its
characteristic, previous studies postulated many structural shapes such as non-convex shape with reentrant
corners and re-entrant honeycomb. In this study, we proposed the rotational particle
structures and investigated the Poisson’s ratio and the ratio (Ee/E) of the elastic modulus of these
structures based on structural design variables using finite element method.
The auto-meshing preprocessor was coded using MATLAB in order to construct numerical
models as design variables and perform finite element analysis (FEA) effectively. Three selected
design variables were the ratio of fibril’s length to particle’s diameter (0.2~2.0), the ratio of fibril’s
length to its width (0.02~0.2) and the angle of fibril about horizontal axis (0 degree ~ tangential
angle). Finite element model has 2D plain stress quadratic element and composed of 515 particles
and 6-linked fibrils per each particle. For all of 213 cases, one side of each model is applied a
tension, 0.1% strain and analyze Poisson’s ratio and the ratio (Ee/E) of the elastic modulus.
As the ratio of fibril’s length to particle’s diameter increased and the ratio of fibril’s diameter to
fibril’s length decreased fixing the fibril’s angle with 45 degree, the negative Poisson effect of
rotational particle structures increased. The ratio of elastic modulus of these structures decreased
with Poisson’s ratio. The results show the reasonable values as compared with the previous
analytical results.
Processing, Microstructure and Mechanical Properties of Hybrid Materials with Al-Mg Alloy and its Composites
Authors: Cho Han Gyoung , Chang Si Young
Published: March 2009

The hybrid materials with Al-Mg alloy and its composites reinforced with SiC and Al2O3
particles were prepared by conventional powder metallurgy method. The Al-5wt%Mg and
composite mixtures were compacted under a pressure of 400MPa and sintered at 873K for 5h. The
obtained hybrid materials with Al-Mg/SiCp composite showed the higher relative density than those
with Al-Mg/Al2O3 composite after compaction and sintering. In the composite side of hybrid
materials, the SiC particles were densely distributed compared to the Al2O3 particles. The hybrid
materials with Al-Mg/SiC composite showed higher micro-hardness than those with Al-Mg/Al2O3
composite. The mechanical properties were evaluated by the compressive test. The hybrid materials
revealed almost the same value of 0.2% proof stress with Al-Mg alloy. However, their compressive
strength was lower than that of Al-Mg alloy, resulting from the fracture occurring along the microinterface
between matrix and reinforcements in the macro-interface.
Study on the Application of Infrared Thermovision Camera for Efficiency Analysis of Solar Cell
Authors: Choi Choul Jun , Kim Jae Yeol , Yang Dong Jo , Song Kyung Seok , Kwac Lee Ku
Published: March 2009

After Industrial Revolution, energy has been recognized as an important factor which
enhances the motive power for industry in the industrial society. However, recently the excessive
consumption of energy pursuant to the rapid expansion of industry created serious problems of the
exhaustion of fossil fuels as well as unusual change in the weather due to the mass discharge of
carbon dioxide. We can say that after all proposals will boil down to the development of New &
Renewable energy. The most suitable source of energy for this required change is solar energy. The
advantages of solar energy are that it is renewable, infinite supplied and environmentally safe energy
source, and the method of energy supply is in small scale and is decentralized. However, solar energy
related products have the problems such as the limitation for installation, problems in maintenance
and insufficient reliability, which have been the barrier to consumers to satisfy the purchase need for
solar heat related products. In this research will perform thermodynamic analysis through the
application of infrared ray thermal imaging camera and will discuss about the applicability of solar
energy system and other fields as well.
A Textile Waste Water Treatment System Using Photocatalytic Reactor and Catalyst Recycle Unit
Authors: Tawkaew Sittinun , Sooknoi Tawan , Jaroenworaluck Angkhana , Panyathanmaporn Thammarat , Supothina Sitthisuntorn
Published: March 2009

A photocatalytic system for wastewater treatment from textile industries was constructed
and tested for its efficiency. The system consisted of two units – a photoreactor for dye
decomposition and a catalyst recovery unit. The photoreactor was an annular plug flow photoreactor
under irradiation of 36 W Toshiba blacklight. The catalyst recovery unit was 42 L of sediment tank
for TiO2 catalyst recovery. In our study, a Cibra Cron red R-W 150% (an anionic azo dye) was used
to prepare a synthetic textile wastewater. The experimental parameters such as flow rate, pH, dye
initial concentration, catalyst loading and setteled time that affected the system performance were
investigated. The photodegradation kinetics were found to follow the Langmuire - Hinshelwood
model and also depended on the TiO2 concentration and the pH. The optimum condition for
photocatalytic decomposition was at pH 3 and at 1 g/L of TiO2 catalyst loading. The reaction rate
constant, k and the adsorption constant, K for the scale-up photoreactor were 3.345 mg/L-min and
0.0204 L/mg, respectively. For the catalyst recycle unit, the overflow and underflow concentration
of the TiO2 catalyst were 2.00 and 0.002 mg/L, respectively, at 100 ml/min of inlet flow rate, 50
ml/min of overflow and 50 ml/min of underflow.
A Study of Alternative Construction Materials for Slag Derived from Steel Making Industry
Authors: Lee Kyung Hoon , You Kwang Suk , Ahn Ji Whan , Ban Bong Chan
Published: March 2009

The present study examined the effect of the activation properties of granulated blast furnace slag
according to the type of alkaline activator, the specific surface area of blast furnace slag, and the amount of
ordinary Portland cement substituted on the compressive strength of the cement containing blast furnace
slag. For activators, Na2SiO3, Na2CO3, NaOH, and Na2SO4 were used. Na2SiO3, Na2CO3, and Na2SO4 were
converted into Na2O, to which 1 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% were added, and subjected to
experimentation, with the W/S (water/solid) ratio = 0.5. The principal hydration products were C-S-H,
C4AH13, Aft (ettringite), and Al(OH)3. Na2CO3 exhibited the largest slag hydration rate. Consequently,
the present study used Na2CO3 as the alkaline activator. The compressive strength of blast furnace slag
cement mortar was then measured according to the amount of Na2CO3 added (2.5 wt.% and 5.0 wt.%), the
specific surface area of blast furnace slag (4,000 cm2/g, 6,000 cm2/g, and 8,000 cm2/g), and the substitution
rate (30 wt.%, 50 wt.%, and 70 wt.%) of the blast furnace slag in terms of ordinary Portland cement. The
results are as follows: at the ages of 1 day and 3 days, respectively, the early strength increased as the
specific surface area of blast furnace slag and the amount of alkaline activator added increased; at the age of
7 or more days, the compressive strength increased as the amount of alkaline activator added decreased and
as the specific surface area of blast furnace slag increased.
Enhanced Photocatalytic Activities of Ta2O5 and Nitrogen Co-Doped TiO2 under Visible Light Irradiation
Authors: Shen Yan Fang , Xiong Tian Ying , Yang Ke
Published: March 2009

Tantalum dioxide and nitrogen co-doped titanium dioxide nanopowders, denoted as
(Ta2O5, N) co-doped TiO2, were fabricated by a high-energy ball miller using TiO2, Ta2O5 and urea
as raw materials. Experiments on the photocatalytic activities of the (Ta2O5, N) co-doped TiO2 were
carried out in the form of photodegradation of methylene blue (MB) in aqueous solution under
visible light irradiation. Enhanced photocatalytic activities were observed for the (Ta2O5, N)
co-doped TiO2 than commercial Degussa P25. Besides, physical, chemical and optical properties,
including XRD, DRS, and XPS were detected to analyze the origins for the enhanced photocatalytic
activities of the prepared samples.
Soft Ground Improvements Using Natural Fiber
Authors: Kim Ju Hyong , Cho Sam Deok , Jang Yeon Soo , Kim Soo Sam
Published: March 2009

In this study, natural fiber drains made with coconut coir, rice straw and jute filter were
tested to evaluate their practical applicability if used in fields properly. Firstly, the tensile strength,
and discharge capacity of the natural fiber drains were tested and verified prior to usage. Based on the
test results, natural fiber drains excelled in tensile strength, but their initial discharge capacity
obtained from composite discharge capacity tests was less than that of plastic drain board. Although
their initial discharge capacity was relatively low compared to that of plastic drain board, the surface
settlement from installation of the natural fiber drains, which is one of the most important factors to
control the construction progress, was identical to that of plastic drain board. Therefore, it was
concluded that the natural fiber drain boards satisfy the required minimum discharge capacity as a
vertical drain and have great potential as a substitute for conventional plastic drain board. Secondly,
long term changes in tensile strength of natural fiber drains embedded in sea water and clayey soil
were examined. The tensile strength of fiber drain board in clayey soils decreased with time. These
results indicated active decomposition of natural fibers embedded in sea water and clayey soils.