bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot Compressive Deformation of Rheocast AZ31 Magnesium Alloy
Authors: Yang Bi Cheng , Zhang Shao Ming , Xu Jun , Shi Li Kai , Fan Z.
Published: March 2009

The billet of magnesium AZ31B was made by twin-screw rheo-cast, and the specimen
cut from the rheo-cast billet and normal cast billet were compressed in Gleeble-3000 hot simulator.
The deformation temperature was 300, 350, and the strain rates were 0.001~1s-1. The relationship
among flow stress, deformation temperature and strain rates were analyzed. The variation of the
microstructure was observed and compared after the specimen was hot compressed. The results
show that the surface of the rheo-cast specimen is much more smooth than the normal cast
specimen after the compression. The dynamic recrystallization had taken place during the
compression and the recrystallized grain of rheo-cast sample is more tiny than normal cast
specimen.
Semisolid Forging of 7000 Series Aluminum Alloys
Authors: Azpilgain Zigor , Hurtado Inaki , Ortubay R. , Landa I. , Atxa J.
Published: March 2009

The achievement of lighter automotive components is an important driving force in the
development and optimization of casting techniques. In this sense, semisolid forming is an emerging
technology that has allowed the production of security components using aluminum alloys. The
foundry alloys A356 and A357 remain, up to the present, the most used alloys for the semisolid
processing of components. Nevertheless, several authors have pointed out the gain in properties that
other alloy families could provide.
In the present work, thixoformability of 7000 series aluminum alloys is studied. Thermodynamic
calculations (CALPHAD method) and calorimetric experiments have been performed to determine
the composition of alloys with an optimum process window. A modification of the 7075 alloy is
proposed in order to improve its thixoformability parameters and optimize the process control. A
simple component has been produced by semisolid forging and mechanical properties have been
measured from tensile samples.
Grain Size Control of Wrought Aluminum Alloy for Rheology Forging by Electromagnetic Stirring and Its Mechanical Properties
Authors: Oh S.W. , Kang C.G. , Kim Byung Min
Published: March 2009

This paper focuses on fabricated slurry by electromagnetic stirring (EMS) with A6061 and
A7075 wrought aluminum alloys. For this EMS process, it is important to find the optimal
electromagnetic stirring conditions such as pouring temperature, stirring current and stirring time.
After electromagnetic stirring according to each condition, the billets fabricated by EMS were
investigated, as was the microstructure and cooling temperature of molten alloy which was directly
cooled from liquid state to the semi-solid state during EMS. In use of cooling time and temperature
data, it is possible to determine the forming time and stirring time required, respectively.
Microstructural Changes of Fe-22Mn-12Cr-4Co-0.3Ti-xSi Alloys During Solution Nitriding
Authors: Sung Jee Hyun , Jung Yun Chul , Kim Yung Hee , Sung Jang Hyun , Kang Chang Yong
Published: March 2009

The microstructural changes of Fe-22%Mn-12%Cr-4%Co-0.3%Ti-x%Si (mass %)
damping steels have been studied during solution nitriding at 1100°C. In the solution nitriding
free specimens, austenite, ferrite and ε-martensite were formed all over the specimens. However,
the original microstructures to form in the solution nitriding free specimens were changed into
single austenite phase by the solution nitriding and fine nitride with coherent relation with matrix
precipitated in the austenite. With increasing Si contents, the amounts of coherent precipitates and
stacking faults decreased and increased, respectively. It has been confirmed that Si hinders the
permeation of nitrogen from the surface to the interior of specimen, suppresses the precipitation
of nitrides such as TiN and AlN, and reduces the energy for the formation of stacking fault and
that solution nitriding is a useful method to improve the surface properties of damping steels.
The Characteristics of Surface Layers Produced on SKD 61 Steel by Plasma Radical Nitriding Compared with Conventional Plasma Ion Nitriding
Authors: Lee Insup , Park Yong Ho , Park Ik Min
Published: March 2009

Plasma radical nitriding has been performed to harden the surface of SKD 61 steel for 1-
10 hours at temperature range of 450-550°C. A NH radical, which has played a key role to produce
a nitrogen diffusion layer without the formation of the brittle compound layer, has been generated in
a gas mixture of NH3 and H2 . One of the main advantages of the plasma radical nitriding is to
improve the surface hardness by maintaining the roughness of the initial polished surface. The
microstructures and material properties of the radical nitrided layer have been characterized in order
to investigate the effects of various radical nitriding processing parameters. The hardness and
surface roughness of the hardened layer were compared between two processes. In addition, PVD
CrN coating has been deposited on both the radical nitrided substrates and conventional nitrided
substrates by an arc ion plating (AIP) technique. The effect of two different of plasma nitriding
treatments on the adhesive strength of the coating layer on the substrates was also investigated.
Influence of Direct Current Field on Powder-Pack Boriding
Authors: Xie Fei , Zhu Qiu Hua , Lu Jin Jun
Published: March 2009

The influence of direct current field (DCF) on powder-pack boriding has been investigated by applying DCF between boriding agent and specimen during the soaking. Experimental results show that DCF has the function of heating the agent and the specimen and thus enhancing boriding. It is shown that the specimen’s side facing anode has the deepest boride case when the specimen is taken as cathode. It is proposed that DCF forces active boron-containing species to diffuse toward the specimen at the cathode. This makes boron concentration around the specimen as cathode higher than that at the anode or other position and that in the conventional powder-pack boriding (CPB), which relatively decreases boron’s absorption by inner wall surface of the pack box and the non-working surface of the specimen. DCF’s physical effect of enhancing chemical reaction in the agent increases the activity and concentration of active boron atoms and boron-containing species, which overcomes the shortcoming that CPB can not produce enough boron-containing species by conventional way of heating.
The Effects of Surface Treatments on Solid Particle Erosion of 12Cr Steels for USC Power Plants
Authors: Urm Kee Won , Lee Sun Ho , Lee J.W. , Lee E.Y.
Published: March 2009

12Cr steels have been applied on the turbine bucket and nozzle partition materials for the ultra super critical (USC) coal-fired power plant. Turbine bucket and nozzle materials are damaged by the solid particles within USC steam conditions. Therefore, they have been protected by the surface treatments such as ion nitriding, boriding and chrome carbide high velocity oxygen fuel (HVOF) spray coating. In this study, the surface treatment effects on the solid particle erosion (SPE) characteristic of 12Cr steels were examined in the temperature range of 540 to 620°C and the mechanisms of surface damage are investigated. The SPE of 12Cr steel originated from micro cutting, whereas, that of boriding and chrome carbide HVOF spray originated from the repeated collision, crack initiation and propagation. In case of 12Cr bare steel, the erosion of soft materials occurred in the impact angle range of 30° to 60° at test temperatures. The SPE resistances of boride and HVOF treated steels in the impact angle range of 30° to 60° at 593°C and 621°C were much higher than those of 12Cr bare steel.
Study on Characteristics of ADI Coated DLC/ TiN /TiAlN Coatings by Cathodic Arc Evaporation
Authors: Hsu Cheng Hsun , Lu Jung Kai , Chen Ming Li
Published: March 2009

In this study, austempered ductile iron (ADI) substrate containing acicular ferrite and
high-carbon austenite in the microstructure is made by austempering treatment at 360. Cathodic
arc evaporation (CAE) coating technique was used to coat DLC, TiN and TiAlN films on ADI for
surface modification. The results showed that the three coatings could be successfully coated onto
ADI through CAE process without altering the unique microstructure of ADI. The structures of the
coatings were identified by XRD, Raman and TEM, respectively. After HRC indentation testing, it
was found that nodular graphite was the initial site of cracking for the coatings and then peeled.
Surface roughness of all coated specimens was increased because the droplets generated on the
substrate surface during the CAE process. Coated ADI had better wearability performance than
uncoated ADI due to higher surface hardness. Coated specimens exhibited higher corrosion
resistance than uncoated ones when they were immersed in separate solutions of both 3.5 wt. %
NaCl and 10 vol. % HCl. In particular, TiAlN had the best corrosion resistance among the coated
specimens.
Dissolution of Cementite Plates by Drawing, Re-Precipitation with Annealing and Corresponding Changes in Tensile Behavior in a Pearlite Steel
Authors: Shiota Y. , Kanie A. , Tomota Yo , Harjo Stefanus , Moriai Atsushi , Kamiyama Takashi
Published: March 2009

The microstructural change with drawing and subsequent annealing for a patented pearlite steel was investigated by means of neutron diffraction. The dissolution of cementite plates with drawing and re-precipitation of spherical cementite particles with annealing after sever drawing were observed. In situ neutron diffraction during tensile loading was performed and it is revealed that the strengthening mechanism of the specimen without cementite differs from that for a ferrite-cementite steel where the load transfer is a main mechanism. The possible strengthening mechanism for the heavily drawn specimen is proposed.
Effects of Co, Ti Interlayer, and Post-Annealing on the Adhesion Property between TiN Coatings and WC-Co Substrate
Authors: Kang Dong Shik , Ok Jung Tae , Heo Su Jeong , Choi Eun Young , Kang Myung Chang , Kim Kwang Ho
Published: March 2009

In order to improve adhesion strength between TiN coatings and WC-Co substrate, two
kinds of interlayer of Co and Ti were pre-deposited before TiN coating process. Thickness and postannealing
effects of each interlayer on the adhesion property were investigated through scratch test
in this work. Introduction of thin Ti interlayer largely enhanced the adhesion strength between TiN
coatings and WC-Co substrate in scratch test. The critical load, Lc2 increased from 64 N without Ti
interlayer up to 130N with Ti one of ~ 0.15 thickness. However, post-annealing of TiN/Ti/WCCo
system at high temperature of 600 reduced the critical load again. The Ti interlayer caused a
deficit of Co content in WC-Co substrate during annealing through diffusion of Co element into Ti
interlayer. The reduction of critical load after post-annealing was believed due to diminution in
mechanical properties of the substrate derived from the Co deficit in WC-Co substrate. On the other
hand, introduction of thin Co interlayer of ~ 0.027 thickness also increased the critical load up to
84 N and improved failure mode, but did not reduce the critical load even after annealing, rather
increased it. And, any Co deficit of the substrate was not found after annealing for TiN/Co/WC-Co
system.
Structural Refinement in High Temperature Annealing of Magnetron Sputtered Titanium Vanadium Nitride Coatings
Authors: Yeung Wing Yiu , Wuhrer Richard , Attard Darren
Published: March 2009

Development of advanced ternary nitride coatings such as titanium aluminium nitride and titanium vanadium nitride has attracted significant industrial interest in recent years. Titanium vanadium nitride is considered one of the advanced ternary nitride coatings of great commercial potential. It is believed with the additional element, the oxidation resistance of the coatings can be greatly improved at elevated temperatures. Furthermore, the type of elements selected can produce unique coating properties that can be beneficial to machining of different materials. This paper is to report a study on the structural stability of nanostructured titanium vanadium nitride coatings in high temperature annealing. Nanostructured titanium vanadium nitride coatings were produced by reactive magnetron co-sputtering on AISI H13 tool steel substrates at 240oC. Heat treatment was applied to the coatings at temperatures up to 1000oC. It was found that an unexpected grain refinement of the coatings occurred in the heat treatment process. Grain size of the coatings was found to decrease from ~200-300 nm to ~150 nm after the heat treatments. A strong TiN/TiVN (200) component was found to exist at temperatures up to 700oC but was depleted at higher annealing temperatures. With a finer and densified grain structure, the hardness of the coatings substantially increased from ~800 HV to ~1700 HV.
Mechanical Properties of TiAlN/CrN Nanolayered Coatings Synthesized by a Cathodic-Arc Deposition Process
Authors: Chang Yin Yu , Wang Da Yung , Hung Chi Yung
Published: March 2009

TiAlN, and TiAlN/CrN nanolayered coatings were synthesized by cathodic-arc
evaporation with plasma enhanced duct equipment. Chromium and TiAl (50/50 at %) alloy cathodes
were used for the deposition of TiAlN/CrN coatings. The effects of bilayer thickness and chromium
content on the microstructure and mechanical properties of TiAlN/CrN nanolayered coatings were
studied. The preferred orientation was changed from (200) in TiAlN monolayered coatings to (111)
plane in the multilayered TiAlN/CrN coatings. The multilayered TiAlN/CrN coating with periodic
thickness of 20 nm and the smallest crystallite size of 28 nm exhibited the highest hardness of 39
GPa. The multilayered TiAlN/CrN coatings also showed the best adhesion strength using scratch
tests. It has been found that the structural and mechanical properties of the films were correlated
with the addition of chromium and nanolayer thickness.
Cooperative Research to Optimize Heat Treating Process Condition by Computer Based Technology
Authors: Watanabe Youichi , Ju Dong Ying , Shichino Hayato , Okamura Kazuo , Narazaki Michiharu , Kanamori Hideo , Ichitani Katsumi , Inoue Tatsuo
Published: March 2009

The three-year activities of Japanese IMS-VHT (virtual heat treatment tool for
monitoring and optimising heat treatment process) project are summarized in collaboration with
international VHT program. A brief introduction of the developed code and the results of a
simulation of the carburized-quenching process of a cylinder, ring, and helical gear are described by
using accumulated databases of material characteristics and cooling conditions. A trial to optimizing
the heat treatment (HT) process by using a database system is presented based on collected data of
practical cases. The goal of this project is to optimize the process, such as gas-carburizing followed
by quenching into oil, and to accumulate heat treatment data to create a knowledge-based database.
Modeling and Experimental Verification of Plastic Behavior of the Martensitic Transformation Plastic Behavior in a Carbon Steel
Authors: Ju Dong Ying , Zhang Wei Min , Matsumoto Y. , Mukai Ryuji
Published: March 2009

The objective of this paper is to extend the capability of analyzing the time
dependence and coupling of temperature, stress and strain effects on the macroscopic and
microscopic structures subjected to quenching, and to introduce a theory of the kinetic of the
phase transformation. Strain due to phase transformation, transformation plasticity and thermal
expansion are the dominant factors that need to be included in the simulation of a quenching
process. The evolution of the microstructure also influences the constitutive equations. In
particular, as the temperature changes from the high to phase transformation, temperature and
then room temperature, the stress-strain relationship changes from elastic-plastic strain. Therefore,
in order to obtain a high strength and ductility in carbon steels, transformation plasticity often has
a major effect in increasing of the residual stress during quenching process. In this paper, we
measured temperature change and distortion occurring during the quenching process of a carbon
steel(SCr420) by thermal simulation machine (Gleeble 1500) are used to determine the parameter of
transformation plasticity due to the generation of martensite. The modeling of martensitic
transformation plasticity is also verified by using of computational simulation of the quenching
process.
A Computational Model for Phase Transformation-Temperature-Distortion Coupling of AISI 5120 Steel
Authors: Lee Seok Jae , Lee Young Kook
Published: March 2009

A coupled model for predicting phase transformation, temperature, and distortion of AISI
5120 steel occurring during heat treatment process has been developed. The phase transformation
kinetic models were made using Johnson-Mehl-Avrami equation and the additivity rule based on
theoretical thermodynamic model and experimental dilatometric data. Especially, the
transformation strains measured during cooling were converted to the volume fraction of each phase
for the kinetic models using a relation between transformation strain and atomic volume change.
The heat transfer coefficients in quench media were calculated by inverse method of the heat
transfer equation to the measured surface temperature history. To predict the temperature and
distortion accurately, the thermal and mechanical data were used as a function of temperature and
each phase based on the experimental data. The coupled model for phase transformation,
temperature, and distortion has been implemented in the commercial finite element software
ABAQUS as user subroutines. The calculated results by the coupled model were compared with the
experimental ones.
On the Microstructure and Fracture Surface of Bainite in JIS SK5 Steel
Authors: Tu Meng Yin , Wang Wen Hsiung , Hsu Yung Fu
Published: March 2009

The microstructure and fracture surface of bainite in JIS SK5 steel have been investigated
using transmission electron microscopy (TEM) and electron back-scatter diffraction (EBSD) in this
study. Specimens were austenitized at 880 for 30 min and then austempered at 300 and 400
for 1hr, as a result, lower bainite and upper bainite were formed, respectively. The lower bainite
phase consists of plate-like bainitic ferrites and embedded cementite platelets, the cementite
precipitated unidirectionally at an angle of 55 to 60 deg deviated from the long axes of the ferrites;
in addition, the upper bainite phase consists of a parallel array of ferrite laths and discrete cementite
layers sandwiched between them. Both the bainite structures have the same ferrite/cementite
orientation relationship, which is close to that of the Bagaryatskii relation. The impact fractographs
of lower and upper bainite structures exhibit brittle failure with cleavage facets, of which the size is
correlated with the width of the bainite sheaves. Moreover, the crystallographic orientation of
cleavage facets has been determined directly by EBSD. The results showed that the cleavage facet
planes of lower bainite structure are close to the {001} plane of ferrite, and they were close to the
{001}, {112} and {123} planes of ferrite for the upper bainite structure.
Effects of Annealing Treatment of Aluminum Substrate on Nanopore Arrangements in Anodic Alumina
Authors: Oh Han Jun , Jang Kyung Wook , Lee Jong Ho , Ki Beom Su , Heo Chang Hoe , Kwon So Hyun , Chi Choong Soo
Published: March 2009

Effects of annealing treatments of aluminum substrate for ordered nanopore arrays formed
by self-organized anodization have been investigated. To observe the relationship between
microstructures of aluminum substrate and nanopore regularity formed after anodization of the
aluminum substrate, aluminum specimens were annealed at 300, 400, and 500 °C. The anodic
alumina layer was prepared by two-step anodizing process in oxalic acid at 40 V. The ordered arrays
of nanopore on anodic alumina were shown to be strongly dependent on the annealing conditions, and
nanopore regularity on alumina template increased with increasing annealing temperature and time.
Phase Transition and Thermoelectric Property of Ultra-Fine Structured β-FeSi2 Compounds
Authors: Hong Soon Jik , Rhee Chang Kyu , Chun Byong Sun
Published: March 2009

FeSi2 compounds were fabricated by rapid solidification and hot pressing, which is considered to be a mass production technique for this alloy. Structural behavior of melt-spun ribbon during heat-treatment and Seebeck coefficient of the hot pressed bulk were systemically investigated and compared with conventionally fabricated alloys. The melt-spun ribbon consists of α-Fe2Si5 and ε-FeSi phase. With increasing annealing time, the phase transition to β-FeSi2 phase occurred more rapidly. 20 min of annealing is sufficient for a homogeneous formation of β-FeSi2 phase in melt-spun ribbon, while it is 100 h in as-cast alloy. In this research, the formation mechanism of β-FeSi2 phase during annealing is a transition of α+ε→β. The microstructure of sintered bulk generally consist of a randomly distributed β-FeSi2 phase with an average grain size of 0.9 μm. The increase of Seebeck coefficient in melt-spun and sintered specimen is due to fine grain size formed by rapid solidification.
The Ultra Fine Grained (UFG) Zn Produced by Ball Milling
Authors: Zhu Xin Kun , Zhao Kun Yu , Li C.J. , Zhang X. , Koch Carl C. , Sergueeva A. , Mukherjee Amiya K.
Published: March 2009

Bulk ultra fine grained (UFG) Zn was produced by in situ consolidation of Zn elemental powder with ball milling at room temperature and annealed for 1 hour at 200 after pure Zn milled. The 150 % elongation is obtained in UFG Zn during tensile test at 20 which is equal to 0.43 Tm (Tm is the melting temperature of pure Zn). The elongation of UFG Zn is higher than the 110 % elongation of nanocrystalline Zn ball milled at tensile elongation. The largest tensile elongation (150%) was observed at room temperature in UFG Zn.
Consolidation of Al2O3 Nanopowder by Magnetic Pulsed Compaction and Sintering
Authors: Hong Soon Jik , Lee Jong Keuk , Lee Min Ku , Kim Wheung Whoe , Rhee Chang Kyu
Published: March 2009

The effect of MPC pressure on the density, microstructure, mechanical properties, and
electrical property of MPCed and sintered bulk was investigated. A detail characterization of the
MPCed and sintered bulk has been performed using XRD, SEM, TEM, Vickers hardness tester, and
breakdown voltage tester. The alumina powder used in this research has a size of 50-200 nm, a
smooth surface and elliptical shape. The obtained density of MPCed and sintered bulk is increased
with increasing MPC pressure from 0.5 to 1.25 GPa. The highest density of 92% in this research is
obtained in the MPCed at 1.25 GPa and sintered bulk, while it is 90 % in the MPCed at 0.5 GPa.
The different Vickers hardness with MPC pressure is associated with the different density and grain
size of bulks. The maximum breakdown voltage of 47 kV/cm is achieved in the bulk MPCed at 1.25
GPa due to the higher density than that of others. In addition, the fracture mechanism of MPCed
and sintered bulk is discussed.
The Heat Treatment of Nanocrystalline Cu2O to Enhance the Catalytic Effect at the Surface Layer
Authors: Uhm Young Rang , Han Byung Sun , Lee Min Ku , Rhee Chang Kyu
Published: March 2009

Cu oxide nano powders were synthesized by the levitational gas condensation (LGC) method, and heated at temperature ranges from 150 to 450 C. The nano powders consist of mainly Cu2O with an average size of 35 nm. The analysis of the IR-spectra of the nanopowders demonstrates that the surface of the sample under an air exposure is coated by hydroxylhydride (-OH, H2O) and hydroxycarbonated [Cu2(OH)2CO3]. The change of the particle size by heat treatment below 450 °C is relatively small. The variation of the adsorption ability is mainly defined under heating at least up to 300 °C, by the surface state of the particles. The catalytic effect was increased at heat treated samples.
The Characteristic Evaluation of Hydroxyapatite Powders Synthesized from CaCO3 Refined from Oyster Shell and H3PO4
Authors: Kim Hye Sung , Ryu Su Chak
Published: March 2009

Hydroxyapatite (Ca10(PO4)6(OH)2, HAp) powders is synthesized using the mixed powders of CaCO3 refined from oyster shells and phosphoric acid (H3PO4-98%, Daejung) as starting materials. The characteristic evaluation and chemical analysis of the synthesized powders is performed by X-ray diffraction (XRD), Fourier-transformed infra-red spectroscopy (FT-IR), and inductively-coupled plasma atomic emission spectroscopy (ICPAES). XRD analysis of synthetic powder by heat treatment at 1300°C for 2hrs shows only HAp peaks corresponding to stoichiometric HAp. It is confirmed by ICP-AES test that impurities such as Zn, In, Ti, Ba, Cd, Pb, and Mn, is not detected at all, but small amounts of Ti and Be is observed (0.099ppm Ti and 0.002ppm Ba). Variation of bone density is measured by giving medication of HAp powder with drinking water into human body continuously for three month. After the medication, the bone density is higher than the medication before. This means that HAp powder made from this process can be used as improver of bone density.
Change of Microstructures of Directionally Solidified Ni Base Superalloy GTD-111 at High Temperature
Authors: Lee Bong Keun , Song Woo Young , Han Tae Kyo , Ye Chang Ho , Whang Hyong Chol , Kang Chung Yun
Published: March 2009

In the case of transient liquid phase diffusion bonding with Ni base superalloy GTD-111,
the bonding temperature was sustained at 1403K ~ 1453K. Thus, the microstructure of specimens
heated at 1403K ~ 1453K was examined. In the raw material, γ-γ' eutectic phases, platelet η phases,
MC carbide and PFZ were clearly observed in interdendritic regions or near the grain boundary and
the size of primary γ' precipitates near the interdendritic regions were larger than the core. The
primary γ' precipitated in the dendrite core dissolved early in the bonding process. γ' precipitated
near the interdendritic regions were partially solubilized and their shape was changed. The
dissolution rate increased with increasing temperature. Phases in the interdendritic regions or near
the grain boundary changed continuously with time at the bonding temperature. At a bonding
temperature of 1403K, the eutectic phases remained, but η phases were transformed from a platelet
shape to a needle morphology and the PFZ region widened with time. The interdendritic region and
near the grain boundary became partially liquid at 1423K and fully at 1453K by the reaction of η
phases and PFZ. The interdendritic region and near grain the boundary became liquid and new
phases which were mixed with η phases, PFZ and MC carbide crystallized during cooling at 1453K.
Crystalline η phases were transformed from a rod shape to a platelet shape with increasing holding
time.
Investigation of the Particle Size Effect on the Peritectic Melting of FeSn2 Particles in FeSn2-FeSn Nanocomposites
Authors: Kwon Young Soon , Choi Pyuck Pa , Kim Ji Soon , Kwon Dae Hwan , Gerasimov K.B.
Published: March 2009

The particle size effect on the peritectic melting of FeSn2 particles in FeSn-FeSn2
nanocomposites was studied using differential scanning calorimetry and X-ray diffraction. FeSn-10
wt.% FeSn2 compounds, mechanically milled for 30 min and slowly heated in a differential
scanning calorimeter, showed incongruent melting at 680 K. Although FeSn2 grains grew from 10
to 40 nm upon heating before peritectic melting set in, the melting temperature was more than 100
K lower than the equilibrium value. A small latent heat during peritectic melting and a large amount
of interfacial energy of FeSn-FeSn2 nanocomposites are held responsible for this large particle size
effect. Grain growth is hardly possible in the case of rapid local heating during mechanical milling.
Therefore, a decrease in the peritectic melting temperature is even expected to be substantially
larger.
Efficiency Improvement of Vacuum Carburizing by Using Natural Gas
Authors: Okumiya Masahiro , Hagi Satoshi , Orita Kazuya , Tsunekawa Yoshiki , Umeda Yoshito , Nagai Takayuki
Published: March 2009

Acetylene and ethylene are frequently used in vacuum carburizing in Japan. In this study
the natural gas which is available from the lifeline is applied to vacuum carburizing. The gas
composition inside the furnace was analyzed by the gas chromatography in order to examine the
carbon infiltration mechanism. Unsaturated hydrocarbon gases (such as acetylene and ethylene) are
generated from the natural gas. The effect of acetylene concentration in the furnace on the carbon
infiltration rate was investigated. The carbon amount which infiltrates into the steel increases, as
acetylene concentration in furnace increases. It is possible that carbon concentration of specimen
surface increases to the cementite precipitation concentration in the short term, when natural gas
flow rate increases in the initial carburizing stage. After that, carbon concentration of specimen
surface does not decrease, even if the natural gas flow decreases, because carbon atoms which are
consumed for diffusion to inside are sufficiently supplied. By using this method, inhibition of soot
generation, reduction of process gas and shortening of the carburizing period are possible. The
carbon concentration profile of the vacuum carburized specimen was compared with the simulation.
Decomposition and Crystallization Induced by High-Energy Ball-Milling
Authors: Kwon Young Soon , Kim Ji Soon , Kim Cheol Eeh
Published: March 2009

Phase transformation induced by ball-milling was studied in this work. It was found that
amorphous Fe90Zr10 ribbons undergo crystallization into BCC α-Fe(Zr) under milling in an AGO-2
mill. The decomposition degree of the amorphous phase increased with increasing milling time and
intensity. Analyses of samples milled at different speeds suggested that the observed crystallization
is a deformation-induced process rather than a thermally induced one. In addition, the
decomposition behavior of a FeSn intermetallic under ball-milling was carefully studied. Upon
milling a large amount of the FeSn intermetallic decomposed into Fe5Sn3 and FeSn2, where the
average grain size of the product phases stayed nearly constant with milling-time. It is suggested
that the mechanically driven decomposition of FeSn results from local melting of powder particles
due to high temperature pulses during ball collisions.
Intimate Heterojunction Structure between Titania and Polythiocyanogen and Its Photovoltaic Effect
Authors: Kim Min Hye , Kim Ji Man , Kwon Young Uk
Published: March 2009

A heterojunction structure between a cubic structured mesoporous titania thin film and polythiocyanogen inside the pores was prepared by electrodeposition technique. UV-Vis absorption and FT-IR spectra show that the electrodeposited material is polythiocyanogen and the SEM images show that polythiocyanogen is infiltrated into the pores of the mesoporous titania film. In addition, this heterojunction structure was fabricated into a photovoltaic cell and the cell performance was tested. The cell showed an overall efficiency of 0.03%.
A Study of Exchange-Coupling Effect on Nd2Fe14B / α-Fe Forming Core/Shell Shape
Authors: Kim Chang Woo , Kim Young Hwan , Lee Don Keun , Jeong In Chul , Kwon Hae Woong , Kang Young Soo
Published: March 2009

We report the core/shell type as the interesting one of the various techniques to prepare exchange-coupled permanent magnet. In this study, the exchange-coupled Nd2Fe14B/α-Fe was prepared by high energy ball mill process and chemical reduction. Nd15Fe77B8 powder prepared by high energy ball mill process was coated with α-Fe nanoparticle by chemical reduction. α-Fe nanoparticle on the ball milled Nd15Fe77B8 was synthesized by chemical reduction with borohydride as a reducing agent in aqueous solution. After annealing, Nd2Fe14B/α-Fe forming core/shell shape has exchange-coupling effect and was identified by using XRD, FE-SEM, VSM, TMA and EDX.
Fabrication of Nanoparticles Supported on Metal Oxides by PS-PVP Block Copolymer Encapsulation Method
Authors: Kim Gil Pyo , Yoon Seung Bum , Jung Young Soo , Ahn Jae Hoon , Baeck Sung Hyeon , Kleiman-Schwarsctein Alan , Mc Farland Eric W.
Published: March 2009

Nanoparticles (Au, Pt, Ru) supported on metal oxides (TiO2, Heteropoly Acid) were prepared by PS-PVP block copolymer encapsulation method. It was confirmed by XPS analysis that the oxidation state of metal is 0 after calcination, which indicates the complete removal of polymer. Synthesized catalysts were characterized by TEM, SEM-EDS, and UV-VIS spectroscopy and it was observed that synthesis and calcination conditions, and the interaction between nanoparticle and metal oxide affected significantly the particle size of metal on the surface of metal oxide. When two different metal precursors were diffused into the core of inversed micelles, nano alloy could be synthesized and the composition of nano alloy was controlled by varying the ratio between the two metal precursors.
Consolidation and Mechanical Properties of Near-Net-Shape Al-21 wt.% Si Component Fabricated by Plasma Spray Forming
Authors: Hong Soon Jik , Patil S. , Rhee Chang Kyu , Seal S.
Published: March 2009

The microstructure and mechanical properties of Al-21 wt% Si components fabricated by
plasma spray forming are analyzed. The microstructure of the plasma spry formed component
showed a homogeneous distribution of fine Si particles embedded in the Al matrix. The grain size
of α-Al varied between 200 to 500 nm and the size of the Si particles was about 50 to 100 nm in the
plasma spray formed component. The room temperature tensile strength of the plasma spray formed
component was 215 MPa with 0.5 % elongation, while for cast material, it was 130 MPa. Despite
the porosities, the ultra-fine microstructure and homogeneous distribution of Si particles embedded
in matrix are the foundation of the increased strength of the plasma spry formed component.
Characterization and Photocatalytic Properties of Transition Metal Doped TiO2 and Nanocomposite TiO2 Powders Synthesized by Mechanical Alloying
Authors: Kim Dong Hyun , Park Ha Sung , Jho Jae Han , Kim Wheung Whoe , Kim Sun Jae , Lee Kyung Sub
Published: March 2009

Transition metal doped TiO2 (Ni, Fe, Cu) and nanocomposite TiO2 powders with rutile
phase were synthesized by mechanical alloying and heat treatment, and were characterized by
XRD, TEM, UV-DRS, and PL (Photoluminescence). Photocatalytic activity was also investigated
with the degradation rate of 4-chlorophenol and measured by total organic carbon analyzer. TEMEDP
and XRD patterns showed that the transition metal doped powders (only alloyed powder) were
in the form of rutile phase with the particle size of 20-30 nm. The average grain size of transition
metal doped powders was in the range of less than 10 nm. However, after heat treatment, the
alloyed powder formed composite of the titanate and rutile phase. The UV-DRS and PL
investigation showed that Ni doped 8 wt% nanocomposite TiO2 had the higher wavelength range
(600-660 nm) (2.0-1.9 eV) than that of the commercial P-25 powder(380-400 nm) by Degussa Co.
indicating that the Ni 8 wt% doped nanocomposite TiO2 shifted the absorption into the visible light
region and thus, enhanced the photocatalytic activity. Further, these results agreed well with TOC
investigation. Formation of titanate in transition metal doped TiO2 due to heat treatment was found
to control the grain growth of nano-sized TiO2 and to enhance its thermal stability at high
temperature.
Micro Catalytic Combustor as a Heat Source for Micro Endothermic Reactors
Authors: Kim Chun Taek , Jin Jung Kun , Kwon Se Jin
Published: March 2009

A micro catalytic combustor was studied as an energy source to supply heat to a micro scale
endothermic reactor. The catalyst bed was made from porous material called Isolite B5 coated with Pt
catalyst by the incipient wetness method. The catalyst bed is inserted in a millimeter scale reaction
chamber and temperature distribution along the outside wall of the reactor was measured by varying
the flow rate and equivalence ratio of the hydrogen and air mixture.
Preparation and Characterization of Polypyrrole-Coated Silicon Nanoparticles
Authors: La Hyun Shil , Jeun Joon Pyo , Choi Jae Hak , Kang Phil Hyun , Lee Youn Sik , Nho Young Chang
Published: March 2009

Silicon (Si) nanoparticles were stabilized by sodium dodecyl sulfate and poly(Nvinylpyrrolidone)
in water, and coated with polypyrrole (PPy) via an in-situ polymerization of
pyrrole with FeCl3. TEM images revealed that the Si nanoparticles were successfully coated with
PPy (average thickness, ~2 nm). The Li/PPy-coated Si electrode exhibited improved discharge
capacities, when compared to that of a reported Li/pure Si electrode. PPy-coatings on the Si
nanoparticles acted as efficient conducting agents and prevented an extraction of the cracked Si
fragments into the electrolyte to some extent.
Magnetic Properties of CeO2 Doped YBCO Oxides
Authors: Lee Sang Heon
Published: March 2009

The electromagnetic characteristics in YBCO superconductor were studied.
Electromagnetic properties of CeO2 doped and undoped YBCO superconductor was evaluated to
investigate the effect of pinning center on the magnetization and magnetic shielding. It was
confirmed experimentally that a large amount of magnetic flux was trapped in the CeO2 doped
sample than that in the undoped one, indicating that the pinning centers of magnetic flux are related
closely to the occurrence mechanism of the magnetic effect. It was concluded that the
electromagnetic characteristics arose from the interaction between the trapped magnetic flux and
weak link of the filament formed in the superconducting bulk.
Comparison of Optical Properties of Pyrazoline Derivative Nanoparticles
Authors: Kang Hyo Sim , Oh Sun Wha , Kang Young Soo
Published: March 2009

We prepared various pyrazoline derivatives which possess dimethylamino-, ethoxy-,
isopropyl-phenyl ring at the 5-position of pyrazoline. The nanoparticles of pyrazoline derivative
ranging from tens to hundreds of nanometers by the reprecipitation method have been successfully
prepared and their optical size-dependent properties have been investigated with UV-vis,
fluorescence spectroscopy, DLS (Dynamic Light Scattering) and SEM. The size-dependent optical
properties of pyrazoline organic nanoparticles have been observed in the order of dimethylamino- >
ethoxy- > isopropyl- in electro-donating characters.
Preparation and Characterization of Anti-Fogging Low Density Polymer Film
Authors: Lee Song , Ahn Byung Hyun , Oh Sun Wha , Kang Young Soo
Published: March 2009

In this work, low density polyethylene (LDPE) was grafted with trifluoroacetic acid allyl
ester using γ-ray irradiation from a Cobalt-60 source at different adsorbed doses. It was found that the
grafting degree increases with the absorbed doses. The highest grafting degree was obtained at 100
kGy of absorbed dose and with 30 wt% of trifluoroacetic acid allyl ester. The grafting was identified
with fourier transform infrared (FT-IR) using a calibration curve reported in literature. Thermal
properties of the functional polymers were studied by thermogravimetric analysis (TGA) and the
surface morphology was investigated by scanning electron microscope (SEM).
Effect of Particle Size on the Oxidation Behavior of Nanophase Tin Synthesized by Inert Gas Condensation
Authors: Kim J.S. , Huh Moo Young , Ahn Jae Pyong
Published: March 2009

Nanophase tin powder having sizes ranging from 6 to 40 nm was synthesized by the inert
gas condensation method using helium as the convection gas. As-synthesized particles smaller than 8
nm were the amorphous tin oxide. As-synthesized particles larger than 10 nm can be characterized by
the core-shell structure comprising inner crystalline tin core and outer amorphous tin oxide shell
having a thickness of about 4 nm. Upon annealing in air, the oxidation of nanophase tin particles
strongly depended on particle size. With increasing particle size, the transformation into the
crystalline phases took places at a higher temperature. Calculation of the size dependent melting
temperature of tin particles indicates that melting of the tin encapsulated with the amorphous tin
oxide took place prior to the oxidation.
An Efficient General Purpose Contact Search Algorithm Using the Relative Coordinate System for Multibody System Dynamics
Authors: Cho Hui Je , Bae Dae Sung , Choi Jin Hwan , Koo Ja Choon
Published: March 2009

Dynamic analysis of many mechanical systems is often involved with contacts among bodies. This paper presents an efficient and general-purpose contact search algorithm for multibody dynamics in the context of the compliance contact force model. While many conventional collision detection algorithms are based on the absolute coordinate system, this paper proposes to use the relative coordinate system in detecting a contact. A boundary box of a defense surface geometry is divided into many blocks. A contact reference frame is defined on the defense body of a contact pair. Since all geometric variables necessary to detect a contact are measured relative to the contact reference frame attached to the defense body, the variables belonging to the defense body are constant, which significantly reduces computation time associated with the contact search. Therefore, the contact reference frame plays a key role in developing an efficient contact search algorithm. Contour of the defense body is approximated by many piecewise triangular patches, while contour of the hitting body is represented by hitting nodes along its boundary. Bounding boxes inside which contain each body of a contact pair are defined at a preprocessing stage to eliminate an exhaustive contact inspection when two bodies are in a distance. If two bounding boxes are turned out to be in a contact during the pre-search, each node on the hitting boundary is inspected to find out to which block the node belongs in the post-search. Since each block dividing the boundary of the defense body has a list of patches, each node on the hitting boundary is tested for a contact only with the patches in the block that the node belongs. Actual contact calculation is then carried out to find the contact penetration used in calculating the compliant contact force. Numerical example is performed to demonstrate the validity of the proposed method.
Proposal of Rationalized Assessment Procedure for Buckling of Thin-Walled Cylindrical Tanks
Authors: Kaguchi Hitohsi , Hamada Koji , Sugiyama Akihisa , Morita Hideyuki , Setta Koji , Ogo Hideyasu , Shirai Eiji
Published: March 2009

As for thin walled cylindrical liquid storage tanks in nuclear power plants, the current elastic design guideline against seismic loading might result in too conservative component design. Therefore, it is thought possible to make the design procedure more reasonable by taking dynamic response reduction into account. Experiments using scaled models as well as numerical analyses were carried out, and seismic behavior of thin walled cylindrical liquid storage tanks was simulated to investigate energy absorption capacity and seismic resistance of those tanks. Based on the test and analysis results, assessment procedure for buckling considering post-buckling behavior has been proposed.
The Sliding and Overturning Analysis of a Free-Standing Cask under Earthquake
Authors: Shie R.F. , Ting Kung , Yu J.S. , Liu C.T.
Published: March 2009

A freestanding spent fuel interim storage facility is possible to be selected to house the
spent fuel for ChinShan nuclear power station in a period of 5 to 50 years. The design specifications
of the storage facility should provide adequate safety assurance under the event of a major
earthquake. ANSYS/LS-DYNA computer code is employed in this study to simulate the dynamic
behavior of the cask under extremely seismic loading, the criterion which is used to judge whether
freestanding cask will slide or overturn is thus established. A cylindrical cask is used as an object
which subjected to safety shutdown earthquake of support pad of ChinShan nuclear power station.
The cylindrical cask will slide but will not overturn is obtained under maximum earthquake loading.
Effect of Loading Frequency on Fatigue Crack Growth Behaviour and Microstructural Damage in P92 HAZ
Authors: Kim Bum Joon , Lim Byeong Soo
Published: March 2009

Various hold periods in a cyclic wave of fatigue load were introduced to investigate loading frequency effects on crack growth behavior and microstructural damage. The crack growth path and microstructural damage characteristics at 600°C in tempered martensitic 9Cr-2W (P92) HAZ of welded steel were studied. Generally, low frequency effect with increasing hold periods affects microstructural damage with microvoids/cavities nucleation due to the effect of creep. Results showed that the fatigue crack growth behavior was sensitive to the loading frequency. As frequency decreased, the fatigue crack growth rate increased and the crack path mode changed from transgranular to intergranular in terms of microstructural damage. As the loading frequency decreased, it was found that the microvoids /cavities and microcracks that formed along the prior austenite grain boundaries ahead of the main crack contributed to the intergranular crack growth.
A Knowledge Representation Framework in Design Repository
Authors: Park Chun Hong , Kang Mu Jin , Ahn Jin Chul
Published: March 2009

This paper proposes a knowledge representation framework for intelligent design platform. The main objective is to develop a schema to represent the explicit as well as the implicit design knowledge, and a method to incorporate it in the design repository. The framework is based on the ontological model composed of the elements: function, behavior, structure and constraint. While structure represents the explicit knowledge of design, function, behavior and constraint incorporate the implicit ones. By an example for injection mold design case, it is shown how and to what extent major intents of a design can be represented.
Mechanical and Electrical Properties of Carbon Nanotubes in Copper-Matrix Nanocomposites
Authors: Baik Seung Hyun , Lim Byeong Soo , Ryu Seung Jin , Choi Dae Hyun , Kim Bum Joon , Oh Se Young , Sung Byung Ho , Choi Jee Hoon , Kim Chul Ju
Published: March 2009

Carbon nanotubes have received considerable attention because of their excellent electrical and mechanical properties. In this study, carbon nanotube - copper nanocomposites with homogeneously dispersed nanotubes within the copper matrix have been fabricated by two different methods; a mechanical mixing process and a molecular-level mixing process, which consists of mixing copper ions with functionalized nanotubes in a solvent. Small punch creep tests showed significantly improved mechanical properties of the nanocomposites. The electrical resistance of the nanocomposites also decreased.
Corrosion and Corrosion Fatigue Characteristics of CF8A Steel Degraded for 3 Months at 400°C
Authors: Bae Dong Ho , Jang Seong Cheol , Lee Gyu Young
Published: March 2009

In this paper, as a fundamental study to evaluate fracture characteristics and material
degradation by corrosion, evaluated electrochemical corrosion and corrosion fatigue characteristics
of CF8A steel using as a material of the piping system in nuclear power plant. CF8A steel was
artificially degraded at 400°C for 3 months. The environmental test condition is 3.5wt.% NaCl
solution of room temperature. Corrosion rate of degraded CF8A steel in NaCl solution of room
temperature increases with concentration of NaCl solution increase. However, concentration of
NaCl solution will be more than 4.0wt.%, it shows decreasing tendency. Crack growth rates of
degraded and not-degraded CF8A steel in air condition do not show remarkable difference.
However, in 3.5wt.% NaCl solution, crack growth rates of them showed higher than ones in air.
Particularly, crack growth rate of degraded material remarkably increases compare to one of notdegraded
material.