bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of HfO2 Dielectric Layer Grown by MOMBE
Authors: Hong J.H. , Myoung Jae Min
Published: March 2009

The chemical and electrical characteristics of HfO2 dielectric layers grown on the p-type Si
substrate by the metalorganic molecular beam epitaxy (MOMBE) technique were investigated. The
XPS spectra showed that the Hf 4f and O 1s peaks shifted to the higher level of binding energy due to
the charge 1transfer effect. Electrical properties were analyzed by C-V and I-V measurements. The
distortion of C-V curve at depletion region is attributed to the effect of deep trap levels existence.
Saturation capacitance and leakage current density were in the range of 207 ~ 249 pF and 0.52 ~ 0.58
A/cm2 respectively, and the flat band voltage shift to the higher voltage appeared as the oxygen flow
rate increased.
Numerical Analysis on the Dissimilar Channel Angular Pressing by Multi-Pass Rolling
Authors: Choi Hyoung Jin , Hwang Beong Bok , Ko B.D. , Lim Joong Yeon , Jang D.H.
Published: March 2009

The dissimilar channel angular pressing (DCAP or CCSS) based on the equal channel angular pressing (ECAP) was numerically modeled and analyzed by means of a rigid-plastic two-dimensional finite element method. Multi-pass rolling is performed in two different manners; the feeding direction of samples into the DCAP-channel is maintained in Route A and the feeding direction is reversed in the Route B. The deformation of AA1100 sheets during the DCAP process comprises three distinct processes of rolling, bending and shearing. The shear deformation of an
amount of 0.5 was concentrated at the corner of the DCAP-channel where the abrupt change in the direction of material flow occurred. Because differences in the shear deformation in Route A and Route B led to the different strain states throughout the thickness of the aluminum sheet, the strain history in the DCAP-channel was analyzed in various thickness layers by the shear and effective strain components.
Shock Consolidation of Sm-Fe-N Magnetic Powders and Magnetic Properties
Authors: Chiba Akira , Ooyabu K. , Morizono Yasuhiro , Maeda Tomoyuki , Sugimoto Shinya , Kozuka T. , Kakimoto E. , Kawahara Koichi , Watanabe T.
Published: March 2009

Sm2Fe17Nx compound is a prospective candidate as a material for high performance
permanent magnets because of its good intrinsic magnetic properties with a Curie temperature
of 747K, a room-temperature anisotropy field of 14T and a room-temperature saturation
magnetization of 1.5T. However, Sm2Fe17Nx compound decomposes to -Fe and Sm nitride
above 873K and conventional powder metallurgy processing techniques fail to meet the
processing requirements. Shock consolidation is a viable alternative to process this compound.
Fully dense Sm2Fe17Nx bulk materials were fabricated by cylindrical explosive consolidation
technique using water as a pressure transmitting medium. Explosive consolidation is
performed under cold state and fully dense materials can be obtained without any degradation
of the characteristics of the powder states. Sound compacts were obtained without any cracks
or teas, and the value of (BH)max of Sm2Fe17Nx compact is 23.8 MGOe.
Synthesis and Crystal Structure of Hexagonal DyMnO3
Authors: Kamegashira Naoki , Sato Hirohisa , Ashizuka Satoshi
Published: March 2009

The magnetic properties were investigated on Co66Fe4B15Si15 amorphous ribbons of
annealed at temperature range from 473 K to 773 K in vacuum (A-batch) and open air (B-batch).
Static permeability from domain wall motion decreases with annealing temperature both in A- and
B-batch sample. The permeability from magnetization rotation increases up to 700 K annealing
temperature, but then decreases. The GMI profiles show a symmetric curve in A-batch samples
irrespective of annealing temperature. In B-batch samples, symmetric profiles are shown up to 650 K
annealing temperature, while they becomes asymmetric for further annealing temperature, due to the
exchange bias-field induced by surface crystalline layer.
Structure Dependent Oxidation of Al Thin Films for MTJ Tunnel Barrier
Authors: Lee Y.W. , Yoon S.M. , Lim J.J. , Hu Ying , Kim Chun Gon , Kim Chong Oh
Published: March 2009

Magnetic tunnel junctions(MTJ) are fabricated as a function of the input power of Al thin
film. Al thin films have pseudo-crystalline structure at 30, 60, 90 W and transform into amorphous
like smooth nanocrystalline state at 120 W. Junction resistance increases as the annealing
temperature increases up to 250 and decrease at 300 at the pseudo-crystalline barrier. When
the barrier has amorphous like nanocrystalline structure, optimum annealing temperature increases
up to 300 . The barrier characteristics are strongly related with the microstructure of AlOx barrier.
Effect of Zr-Substitution on the Magnetic Property of a YIG Ferrite
Authors: Yang S.J. , Kim S.D. , Kim Ji Soon
Published: March 2009

Yttrium Iron Garnet (YIG) has been used as an important material in the Circulator/Isolator
which is used in RF communication system, mobile phone, and satellite broadcasting, etc. In this
study, we investigated the variation of electromagnetic properties of YIG ferrites for
Isolator/Circulator application with Zr addition. The YIG ferrites,
Y2.1Ca0.9Fe4.4-xV0.5In0.05Al0.05ZrxO12 with x=0, 0.05, 0.1 and 0.2, were prepared by the conventional
ceramic sintering process. The Zr-substituted YIG ferrite, Y2.1Ca0.9Fe4.4-xV0.5In0.05Al0.05ZrxO12,
showed the highest saturation magnetization (1097 gauss) at x=0.1. Good microwave properties were
shown as isolation of 18.60 dB and insertion loss of 0.45 dB at x=0.2. In addition, the ferromagnetic
resonance (FMR) linewidth decreased as Zr content increased
Magnetotransport Properties in a Lateral Spin-Injection Device with a Ferromagnetic/Si/ Ferromagnetic Junction
Authors: Hwang Woong Joon , Lee H.J. , Lee K.I. , Lee J.M. , Chang J.Y. , Han S.H. , Kim Y.K. , Lee W.Y. , Shin Moo Whan
Published: March 2009

The spin transport in a lateral spin-injection device with an FeCo/Si/FeCo junction has
been investigated. Magnetoresistance (MR) signals were found to appear at low magnetic fields in
the range 4  300 K. This is attributable to the switching of the magnetization of the two
ferromagnetic contacts in the device for certain magnetic fields over which the magnetization in one
contact is aligned antiparallel to that in the other. Our results suggest that the spin-polarized
electrons are injected from the first contact and, after propagating through the bulk Si, are collected
by the second contact.
Finite Element Method in Powdered Metal Compaction Processes
Authors: Ko B.D. , Jang D.H. , Choi Hyoung Jin , Lim Joong Yeon , Hwang Beong Bok
Published: March 2009

A finite element method for the compaction process of metallic powder is introduced in the present work. Basic equations for the finite element formulation are summarized. A yield criterion, which is modified by describing asymmetric behavior of powder metal compacts, is introduced and applied to various classes of powdered metal compaction processes. Three material parameters are involved in the yield function and determined from the behavior of sintered powder compacts as a function of relative density. The FEM simulation includes single-action and double-action pressings of solid cylinders as well as cylindrical rings of relatively long parts (Class II parts). The compaction process for multi-level flanged components (Class III and Class IV parts) is also analyzed. The predicted results from simulations are summarized in terms of density distributions within the compacts and pressure distributions exerted on the die-wall interfaces, and also in terms of
effectiveness with increased relative motions with in the compacts and the effect of various compaction schemes of combination of punch motions. Results obtained in the multi-level compaction process are discussed in terms of average relative density distributions at each height.
Apatite Formation on PDMS-Modified SiO2-CaO-P2O5 Hybrids Prepared with Different P2O5 Content by Sol-Gel Method
Authors: Seo Do Won , Kim J.G. , Kim Yun Hae , Whang Chin Myung
Published: March 2009

Bioactive ORMOSILS (organically modified silicate), PDMS-CaO-SiO2-P2O5 with five different
P2O5 content (0, 0.01, 0.03, 0.06, 0.09 mol%) have successfully been synthesized by sol-gel process.
The hybrids have been prepared with polydimethylsiloxane (PDMS), tetraethoxysilane (TEOS),
calcium nitrate tetrahydrate [Ca(NO3)2

4H2O] and triethyl phosphate (TEP) as starting materials
and subsequently soaked into the simulated body fluid (SBF) for different period of time and the
bioactivity of hybrids was determined by examining the apatite formation on the surface of the
specimen by FT-IR, Thin-Film X-ray Diffraction, and Scanning Electron Microscopy (SEM). All of
the prepared samples with different P2O5 content showed in vitro bioactivity. It was observed that
the increase in P2O5 content up to 0.03 mole % increases the apatite formation compared to P2O5-
free hybrids. However, further increase in P2O5 concentration slows down the formation of the
apatite layer most probably due to the decrease of pH of SBF by dissolution of a large amount of
phosphate ions.
Study of Phase Transformation of Nano Al2O3 Compacts Derived by Hydrolysis and Subsequent Thermal Sintering of Al Powders
Authors: Uhm Young Rang , Lee Geun Hee , Park J.H. , Kim Wheung Whoe , Rhee Chang Kyu
Published: March 2009

Al2O3 compacts with various phases were prepared by hydrolysis and spark plasma
sintering (SPS) process of Al powder. The bayerite (-Al(OH)3) phase was derived by hydrolysis of
commercial Al powder with micron size, whereas the bohemite (AlO(OH)) phase was obtained by
hydrolysis of nano Al powder synthesized by pulsed wire evaporation (PWE) method. Compaction as
well as dehydration of both bayerite and bohemite was carried out simultaneously by SPS method,
which is used to fabricate nano powder into dense compacts with a rapid heating rate of about 100 °C
per min. under the pressure of 50 MPa. After compaction in the temperature ranges from 350 °C to
1100 °C, the bayerite and bohemite phases change into various alumina phases depending on the
compaction temperatures. The bayerite shows the phase transition of Al(OH)3 -Al2O3 -Al2O3
-Al2O3 sequences. On the other hand, the bohemite experiences the phase transition from
AlO(OH) to -Al2O3 at 350 °C showing AlO(OH) -Al2O3 -Al2O3 -Al2O3 -Al2O3
sequences.
Synthesis of Ultra-Fine Iron-Oxide Nano-Particles in a Diffusion Flame with Electro-Spraying Assistance
Authors: Ahn Kang Ho , Ahn Jung Ho , Jeon K.-S. , Choa Yong Ho
Published: March 2009

Ultra-fine Fe2O3 nano-particles are synthesized using H2/O2 co-axial diffusion flame with
the state-of-the-art electro-spraying (e-spray) technique at atmospheric condition. Fe(CO)5 is used
as a precursor and the liquid phase Fe(CO)5 is injected directly into the center of the flame using the
electro-spraying method. The synthesized particle morphology sampled from the inside of flame is
analyzed by TEM. The synthesized particles showed different crystal structures for different particle
collection method and the collection positions.
Creep Analysis of Cr-Mo Steels Using a Dislocation Based Constitutive Modelling
Authors: Kim Hyoung Seop , Seo Min Hong , Hong Sun Ig , Kim Sung Ho , Ryu Woo Seog
Published: March 2009

In order to analyze the creep behaviour of Cr-Mo steels, an elasto-viscoplastic
constitutive model based on dislocation density considerations is described. A combination of a kinetic equation, which describes the mechanical response of a material at a given microstructure in terms of dislocation glide, and evolution equations for internal variables characterising the microstructure provide the constitutive equations of the model. Microstructural features of the material are implemented in the constitutive equation. The internal variables are associated with the total dislocation density. The model has a modular structure and can be adjusted to describe a particular type of materials behaviour and metal forming processes. In this paper, the predicted creep behaviour of Cr-Mo steels is compared with the experimental results.
Application of Water-Based Alumina Tapes Prepared Using PVP Binder for All-Ceramic Dental Crowns
Authors: Choi Se Young , Park Il Seok , Lee Deuk Yong , Han Jung Suk , Kim Dae Joon
Published: March 2009

Aqueous alumina tapes were prepared by a doctor blade using polyvinyl pyrrolidone (PVP)
as a binder and gelatin and polyvinyl alcohol (PVA) as additional binders to improve drying rate and
mechanical properties of the tapes containing PVP. As binder was prepared by mixing 89.5 wt% of
PVP, 10 wt% of PVA, and 0.5 wt% of gelatin, tape properties were optimized showing complete
drying in 3h, tensile strength of 1 MPa, and high flexibility. Marginal gap of all-ceramic dental
crowns prepared using the tapes was about 56 µm indicating the tape cast alumina dental crowns are
clinically applicable.
Cu Nanowire Structures Inside Carbon Nanotubes
Authors: Choi Won Young , Kang Jeong Won , Hwang Ho Jung
Published: March 2009

We have investigated the structures of copper nanowires encapsulated in carbon
nanotubes using a structural optimization process applied to a steepest descent method. Results
show that the stable morphology of the cylindrical ultra-thin copper nanowires in carbon nanotubes
is multi-shell packs consisted of coaxial cylindrical shells. As the diameters of copper nanotubes
increases, the encapsulated copper nanowires have the face centered cubic structure as the bulk. The
circular rolling of a triangular network can explain the structures of ultra-thin multi-shell copper
nanowires encapsulated in carbon nanotubes.
Comparison of Metal-Oxide Nanoparticle Formation in the Cu and Sn Thin Films by the Reaction with Polyimide
Authors: Park Hwan Pil , Chung Yoon , Yoon Chong Seung , Jo Sung Su , Kim Young Ho
Published: March 2009

We developed a simple method of producing metal oxide nanoparticles by reacting a
polyamic acid (PAA) with Cu or Sn metal films. Respective particle size, distribution, and
morphology were characterized by transmission electron microscopy (TEM). The morphology of
metal oxides dispersed in the polyimide is different in Cu and Sn metal films. The Cu2O particles
were formed by the dissolution reaction between the polyamic acid and the Cu films. During curing,
PAA dehydrates and converts to polyimide, accompanied by precipitation of Cu2O particles. The
synthesized Cu2O particles were randomly dispersed within the polyimide. And their particle size was
relatively uniform, having a narrow distribution. Mostly nanosize Cu2O particles were formed in the
specimen made from 10 nm thick Cu film and the mixture of nanosize particles and Cu layers were
observed in the 30 nm thick Cu film. On the other hands, the Sn film undergoes surface reaction with
the polyamic acid. Therefore, the synthesized SnO2 particles existed only at the surface of the
substrate. SnO2 particle size distribution was not uniform in the polyimide. Although particles were
not distributed uniformly in the polyimide, they were confined in a monolayer. The different particle
distributions were attributed to the reactivity difference of PAA with Cu and Sn films.
Fabrication Parameters for Highly Ordered Nano-Pore Arrays in Alumina Template
Authors: Chi C.-S. , Jeong Y. , Kim S.S. , Park Chong Sung , Oh H.J.
Published: March 2009

The fabrication parameters for highly ordered nanopore arrays formed by self-organized
anodization on aluminum have been investigated. To fabricate ordered nanopore arrays in alumina
layer a two-step anodization process was used in oxalic acid solution. The regular nanopore
arrangement, interpore distance and pore diameter in alumina surface were strongly dependent on
the applied potential at anodization. The interpore distance and pore diameter increased with anodic
applied potential, and hexagonally ordered pore arrangements in alumina were obtained by
anodization at 40V. For the effects of the heat treatment of aluminum substrate on size of domains
with same pore orientation, the domain size increased with increasing annealing time.
Photocatalytic Ecomaterials
Authors: Shin Hong Dae , Joo Hyun Ku , Park Jae Hyun , Lee Chung Hyo
Published: March 2009

In this study, photocatalyst-coated glass beads by CVD, N-substituted TiO2 for visible light
activation, plastic optical fiber bundle and treated Ti plate were considered as Ecomaterials for the
potential use in photocatalytic environmental purification system. Each material was carefully
prepared and characterized to use in real system either by itself or together for a specific application.
The absorption edge of the obtained TiON was ca. 530 nm and the presence of photocatalytic activity
of the material under visible light was evidenced.
Wear and Bioconductivity Characteristics of Oxidized Ti-29Nb-13Ta-4.6Zr
Authors: Li Shu Jun , Yang Rui , Niinomi Mitsuo , Hao Yu Lin , Cui Yu You
Published: March 2009

. An investigation of wear and bioconductivity characteristics of oxidized Ti-29Nb-13Ta-
4.6Zr is presented. Experimental results showed that oxidation treatment at 400oC for 24h in air
results in the formation of a hard layer on the surface of the alloy, which greatly benefits its wear
resistance. Calcium phosphate (Ca-P) phase was found to grow on the oxidized and alkali treated
Ti-29Nb-13Ta-4.6Zr alloy samples when they were immersed in a protein-free simulated body fluid
or fast calcification solution.
Synthesis of Apatite Ceramics with Preferential Crystal Orientation
Authors: Nakano Takayoshi , Fujitani Wataru , Umakoshi Yukichi
Published: March 2009

Biological hard tissues show preferential alignment of the c-axis of biological apatite (BAp) crystallites depending on the shape and stress distribution in vivo, but apatite-base bioceramics developed for bone grafting have no preferential BAp orientation. Thus, the crystal orientation was controlled for developing novel bioceramics with apatite (Ap) texture similar to biological hard tissues.
Since cortical portion in a bovine femur shows a one-dimensional orientation along the longitudinal direction of long bone, the effect of heat treatment on Ap orientation was investigated in the femur bone as a starting material. Heat treatment was performed first at 600°C for 1h to remove organic constituents and subsequently at each temperature between 700°C and 1300°C. Crystal orientation and texture of BAp were measured by the micro-beam X-ray diffractometer.
Size of BAp crystallites increased remarkably after a heat treatment even at 600°C for 1h and a great amount of pore remained in the Ap ceramics in exchange for the organic constituents. Several Ap grains were surrounded as a group by the pores, but additional heat treatment in a temperature range up to 900°C reduced the number of Ap grains in the group, and finally became a single grain region at 1000°C. Pore density decreased with increasing annealing temperature, especially above 1000°C. One-dimensional preferential alignment of the c-axis in Ap maintained during all the heat treatment and the degree increased with increasing annealing temperature because a lot of low-energy low angle boundaries against the c-axis existed in the starting material and preferentially remained in the synthesized Ap ceramics.
It was therefore concluded that adequate heat treatment of bovine femur can give the preferential crystal orientation in Ap ceramics.
Study of Magnetic Annealing on Magnetostriction in Grain-Oriented 3.2 % Si Steels
Authors: Cha Sang Yun , Chudakov I.B. , Woo Jong S. , Kim Jong Kweon , Cho Young Rae
Published: March 2009

The effects of magnetic annealing on a magnetiostriction in commercial grain-oriented 3.2 at.% Si steels were investigated. A combined (constant+strong pulsed) magnetic field during the magnetic annealing played a significant role in reducing the magnetostriction. The reduction ratio in magnetostriction was greatly dependent on surface conditions such as whether it was a bare metallic, tension coated and laser-scribed surface for grain-oriented electrical steels. For all three samples, the effect of the magnetic annealing on reduction in maganetostriction is more clearly observed in the compressive stress rather than in the tensile stress region.
Toughness Assessment of a Variety of Materials: Similarities and Discrepancies
Authors: Kobayashi Toshiro
Published: March 2009

To determine the toughness of materials, Charpy V notch test has been widely utilized over the world. This method is easy to conduct, but obtained values are some what qualitative. Instrumented test has also a long history and gives us a loading history during impact. However this method is also still remaining in the range of a screening test. The author has successfully developed CAI (Computer Aided Instrumented Impact Testing) System for the evaluation of dynamic fracture toughness. In this CAI system, dynamic fracture toughness parameters such as Kd, Jd, Tmat and various absorbed energies can be obtained from the load-deflection curve of a single precracked specimen for both ductile and brittle materials
Composition Design and Ageing of Ni-Mn-Ga Alloys
Authors: Jin Xue Jun , Peng Z.M. , Allen Samuel M. , O'Handley Robert C. , Hsu T.Y.
Published: March 2009

Ni-Mn-Ga ferromagnetic shape memory alloys (FSMA) are a potential new class of actuator materials able to respond at higher frequencies (at least 300 Hz) with comparable strains (up to 6 %) in a moderate field (below 1 T)[1]. Magnitude of the strain depends on the values of several critical material parameters, most importantly the martensitic transformation temperature (TMart), Curie temperature (TC) and saturation magnetization (MS)[2]. It is well known that these parameters are strongly dependent on the composition of the alloy. Composition dependence of TMart, TC and MS have been experimentaly explored [3,4]. Therefore, it is possible to compile a more complete, and hence more useful composition map for designing Ni-Mn-Ga FSMAs.
Ageing behavior is important in these newly developed FSMAs because ageing can affect the reliability of devices using the alloys. Ni-Mn-Ga FSMAs and Au-Cd[5] alloys have several important common characteristics, including off-stoichiometry alloy composition (designed for operation at ambient temperature) and easy twin boundary motion in the martensite state, thus similar ageing behavior is expected in Ni-Mn-Ga alloys.
Ni-Mn-Ga alloys have also demonstrated strong damping due to the motion of twin boundaries[6]. Low-frequency mechanical properties are typically measured using the technique of dynamical mechanical analysis (DMA)[7].
In this paper, we present studies of composition design, subtle structure changes associated with ageing, and the temperature dependence of the low-frequency mechanical properties of several Ni-Mn-Ga single crystal alloys.
Property of TiNi Shape Memory Foils Produced by Ultrafine Laminates Method
Authors: Tsuchiya Koichi , Tomus Dacian , Umemoto Minoru , Sasaki Masahiro , Ohmori Toshiki
Published: March 2009

Using the ultrafine laminate method, thin foils (50 µm) of Ni-rich TiNi shape memory
alloys were produced. Overall composition of the Ti/Ni laminate is Ti-50.7%Ni. TiNi (B2) phase was
obtained after different diffusion treatments at 1073 K for 36 ks. Aging treatment at 773 K for 3.6, 18,
36, 72 and 144 ks were also performed. Phase transformation behavior of aged foils changed from
two-step, to three-step and then to two-step transformation, which is similar to the case of bulk TiNi
alloys. Uniform distribution of Ti3Ni4 phase was observed for aged samples by transmission electron
microscopy. Two-way shape memory effect of the aged TiNi foil was also demonstrated.
Microstructure Characterizations of Hypereutectic Al-Si Alloys with Different Undercooling Levels
Authors: Kang H.S. , Yoon W.Y. , Kim Kwon H. , Kim M.H. , Yoon Eui Pak
Published: March 2009

Microstructural variation is quantitatively characterized by measured undercooling. For neareutectic Al-13wt%Si alloys, microstructure transitions, which include a phase change from eutectic to primary α-Al dendrite plus eutectic and a morphological change from α-Al dendrite to equiaxed Al grains, were observed with increasing undercooling levels. For hypereutectic Al-Si alloys, microstructure transitions, which include a morphological change of primary and eutectic Si crystals, were also obtained quantitatively by increasing undercooling.
Synthesis of Porous Mullite by Vapor Phase Reaction
Authors: Cho Bum Rae , Kang Jong Bong
Published: March 2009

The porous microstructure with acicular mullites was fabricated using Al(OH) 3, Al 2O 3, and amorphous SiO 2 as starting materials by reaction sintering. Several molar ratios of Al 2O 3/SiO 2 and Al(OH) 32 were selected and AlF 3 of 0, 4, 7, 10wt% was added to each composition to examine the effects of composition and the additives for the mullite formation. Fluorotopaz was produced at a temperature around 900°C under a constant SiF4 atmosphere and it was decomposed to produce the mullite at a relatively low sintering temperature around 1200°C. The acicular mullite was more easily fabricated in the case of the Al(OH) 32 mixture with a larger amount of AlF 3.
Sinter-Bonding of Polycrystalline Silicon-Nitride Using Source Powder of Superplastic Ceramics as Insert Material
Authors: Motohashi Yoshinobu , Waseda Kazuyoshi , Kitahora Kazuhiko
Published: March 2009

A sinter-bonding method for a typical structural ceramic, Si3N4, has been studied by making good use of 3Y-ZrO2/Al2O3
composites powder as an interlayer. During the process of the sinter-bonding, the sintering of the inserted powder as well as the bonding of the interfaces, Si3N4/ inserted powder /Si3N4, progressed imultaneously. Since superplasticity in the 3Y-ZrO2/AlO3 composites can arise after, even during, the sintering process under proper bonding temperature and stress conditions, the surface roughness of the Si3N4
to be bonded can be filled up mainly by the material flow of the interlayer even though the surfaces are uneven and have curvatures. It was found that the sinter-bonding of the polycrystalline Si3N4 specimens was completed at temperatures ranging from 1573 to 1813 K with bonding stresses ranging from 4 to 10 MPa, at which superplastic flow of the inserted material would
arise, whereas the Si3N4 showed no permanent deformation. The bonded Si3N4 specimens showed the bending strength of more than 300MPa at room temperature.
Efflorescence and Leaching Behavior of Metal Ions for EAF Dust-Clay Based Bricks
Authors: Kim Jung Hwan , Lee Ki Gang , Kim Y. , Kang S.K.
Published: March 2009

Brick samples were prepared through vitrification process with two different kinds of EAF dust. Leaching concentrations of various metal ions and anions for the bricks(20wt% EAF dust-80wt% clay) were evaluated by ICP and IC analysis. The results of leaching test showed that the concentration of ions leached from bricks were proportional to the square root of time and saturated with leaching time. The saturated concentrations of alkali and alkali-earth metal ions were 0.1-250ppm; on the other hand, the heavy metal ions were 0-0.084ppm. The efflorescence mechanism of EAF dust-clay bricks was studied by quantitative analysis for the effects of various metal ions and anions. Efflorescence formed on the brick surfaces which were immersed in DI water and dried slowly in the air were characterized by SEM, EDS and XRD. The results of EDS and XRD showed that the main component
of the efflorescence was water soluble Na2SO4 .
Nanocomposite Formation in the Fe2O3-M (M=Al, Ti, Zn, Cu) Systems by Mechanical Alloying
Authors: Lee Chung Hyo , Lee S.H. , Chun S.Y. , Lee Sang Jin , Kwon Young Soon
Published: March 2009

Nanocomposite formation of metal-metal oxide systems by mechanical alloying
(MA) has been investigated at room temperature. The systems we chose are the Fe 2O 3-M(M=Al,Ti,Zn,Cu), where pure metals are used as reducing agent. It is found that nanocomposite powders in which Al 2O 3 and TiO 2 are dispersed in Fe matrix with nano-sized grains are obtained by mechanical alloying Fe 2O 3 with Al and Ti, respectively. However, the reduction of Fe 2O 3 with Cu by MA is not occurred. And the system of Fe 2O 3-Zn results in the formation of FeO plus ZnO after 120 h of milling. It is also shown that the magnetic evidence for the solid state reduction by mechanical alloying through changes in saturation magnetization and coercivity.
Effect of CoO Doping on the Sintering Ability and Mechanical Properties of Y-TZP
Authors: Onda Tetsuhiko , Yamauchi H. , Hayakawa Motozo
Published: March 2009

The effect of CoO addition into Y-TZP (Yttria doped Tetragonal Zirconia Polycrystals) was studied on the evolution of its sintering ability, grain size, grain boundary structure and mechanical properties. The doping of a small amount of CoO effectively reduced the sintering temperature. A small amount of CoO up to ~ 0.3 mol% was effective for the suppression of grain growth, but the addition of 1.0 mole % resulted in an enhanced grain growth. The hardness and toughness of the CoO doped TZP were about the same as those of undoped TZP. Furthermore, despite the grain refinement, CoO doped TZP did not exhibit improved mechanical properties. This
may be suggesting that CoO dopant had weakened the grain boundary strength.
Resistance Sintering of Copper-Graphite Powder Mixture under Pressure
Authors: Maki Seijiro , Harada Yasunori , Mori Kenichiro
Published: March 2009

Resistance sintering characteristics of electrolytic and atomized copper powders mixed with graphite powder in steps of 10vol% up to 50vol% were experimentally investigated. In the experiments electrifying voltage and time, and applied pressure were varied. Post-electrification pressurization and insertion of low thermal conductive austenitic stainless steel discs between the sintering powder cake and electrodes were attempted to promote the sintering. The effects of the operational parameters including the two devices on sintering performance are discussed. Sintering strength of the resistance-sintered composites is also discussed.
Fabrication of Thin Film Using Nanosized Indium Tin Oxide (ITO) Powder and Its Degradation Characteristics
Authors: Kim Yong Nam , Park Jeong Hyun , Shin Hyun Gyu , Song Jun Kwang , Lee Hee Soo
Published: March 2009

Nanosized ITO powder was fabricated by homogeneous precipitation which used formamide as a precipitator. ITO thin film was deposited by RF magnetron sputtering using ITO target which was prepared by sintering of nanosized ITO powder. From the accelerated degradation test with stress factor of temperature, the lifetime estimate, degradation rate/degree, activation energy and etc. were calculated. It was showed that under thermal condition, the prominent failure mechanism of degradation was the decrease of oxygen vacancies due to oxidation of ITO thin film.
Photocatalysis for Oxidation of Phenol and Reduction of Inorganic Pollutants by Nanocrystalline TiO2-ZrO2 Powders
Authors: Han Jae-Kil , Choi Sung Min , Oh Ik Hyun , Saito Fumio , Lee Byung Teak
Published: March 2009

TiO2(1-.ZrO2. (.=- 0.2, 0.4, 0.6 and 0.8) composite powders having a homogeneous distribution and nanocrystalline were successfully synthesized by sol-gel process using titanium iso-propoxide as precursor. The particle sizes of TiO2-ZrO2 powders calcined at 600°C were measured ranging from 10nm to 19nm by XRD and TEM. For the comparison of photocatalytic activity, TiO2-ZrO2 composite powders were tested in the degradation of phenol and the photoreduction of inorganic pollutants. The degradation of phenol increased with increase the content of anatase TiO2 phase.
Up-Grade Recycle by Consolidating Aluminum Cutting Chip under Severe Plastic Deformation
Authors: Toda Hiroyuki , Kobayashi Toshiro
Published: March 2009

Cutting chip is, generally, remelted for recycling solely as raw materials. In terms of
microstructures, however, the cutting chip may be identified utilizable due to highly accumulated strain during its formation. In this study, aluminium chipsareconsolidated by cold severe plastic deformation so that their highly deformed microstructure is utilized for strengthening. After a preliminary investigation in which a variety of cutting processes and conditions are examined to find the optimum one for the present purpose, the aluminium chips have been successfully consolidated by a combination of pressing and swaging. The consolidated chips exhibit superior strength to a wrought alloy together with finer microstructure when compared at a same applied strain. In addition, a simple method is demonstrated effective to eliminate the undesirable effects of oxide film on the surface of
the chips, which inevitably causes debonding during loading.
Effects of Deformation on Surface Modification by Nitrogen Ion-Implantation
Authors: Yamamoto Atsushi , Tsubakino Harushige , Ando Masami , Liu Lie , Terasawa Mititaka , Mitamura Tohru
Published: March 2009

Ion-implantation on high purity iron substrates with nitrogen ions were carried out by
using a Cockcroft Walton type accelerator under an accelerating voltage of 150 kV. Hardness measurements on the implanted surfaces showed that hardness effectively increased in the cold rolled specimens by ion-implantation in comparison with in an annealed specimen. Iron nitride, Fe16N2, was formed in the ion-implanted specimens. In the annealed specimen, relatively large
particles of Fe16N2 were formed with low number density, while in the deformed specimens, dislocation substructures due to cold rolling were disappeared by ion-implantation and fine particles were densely formed. Strain field around dislocations induced by deformation provides nucleation sites for Fe16N2 particles.
Improvement of Inner Surface for Machine Parts by Shot Peening
Authors: Harada Y. , Maki Seijiro , Mori Kazuya , Wang Lei
Published: March 2009

Shot peening process of inner surface of machine parts in which rebound shots collide with the inner surface was investigated. The jig used for rebound shot peening has the surface with a slope to the inner surface of machine parts, and the collision direction of shots was vertical to the inner surface. In this process, a compressed air type shot peening machine was employed. The influence of processing conditions was evaluated by the distributions of hardness, residual
stress and surface roughness in the test pieces of pipes and coiled springs. The effect of shot peening increases with the increase of shots collision energy. A stress peening process for inner surface of coiled springs using rebound shots was also performed. The coiled spring was provided higher compressive residual stresses. The results of a fatigue test showed that the fatigue life of the spring was improved. The compressive residual stress reduces the tensile stress of coiled spring. It was found that the present process was suitable for improving the inner surface of machine parts.
Vertical Etching of Ru Electrodes Using the O2/Cl2 System
Authors: Kim Hyoun Woo
Published: March 2009

In this study, the etching characteristics of ruthenium (Ru) electrode using O2/Cl2 helicon plasmas were investigated. The variation of Ru etch rate, Ru to SiO2 etch selectivity and Ru etching slope with varied process variables were scrutinized. Not only the gas chemistry affected the Ru etching, but also the higher bias power and argon (Ar) bombardment helped to faciliate the Ru etching.
Property of Laser Welded Bake-Hardening Steel in Tailored Blanks for Automobile
Authors: Matsui Fumiaki , Shibao Masami , Yoshida Naoharu , Shibata Kimihiro , Sakamoto Hiroki , Sakurai Hiroshi , Hirose Akio , Kobayashi Kojiro F.
Published: March 2009

The behavior of bake-hardening of the laser weldment was investigated. The bake-hardening steel(BH steel) was welded with Nd:YAG laser followed by plastic deformation and subsequent heat-treatment. Then the influence of laser welding on the behavior of bake-hardening was investigated. The hardness of the laser weld metal significantly increased after welding. After the plastic deformation, both the base metal and weld metal became harder by work-hardening. The heat treatment resulted in more increment of hardness in both the base metal and weld metal by
bake-hardening. The amount of bake-hardening reached a maximum value at the plastic strain of 5% or more. We modified a kinetic equation proposed for predicting the strength of a low-carbon bake-hardening steel and applied to the estimation of hardness of the base metal and weld metal. The calculated hardness values agree with the experimental data. The calculated activation energy for bake-hardenig was that for diffusion of carbon and nitrogen atoms in α-Fe. Thus the hardening is
thought to be governed by diffusion of these solute atoms.
Explosive Welding of Thin Plates Using Underwater Shock Wave for Surface Modification
Authors: Ujimoto Yasuhiro , Hokamoto Kazuyuki , Lee J.S.
Published: March 2009

This paper presents a new method of explosive welding using underwater shock
waves. The method renders the possibility of accelerating a thin metal plate uniformly at a velocity above a few hundreds m/s to satisfy the explosive welding requirements. The welding of a thin titanium plate onto a stainless steel base and other welding experiments were performed underwater. The bonding strength at the interface is observed to be high because the materials are welded based on the mechanism of explosive welding. The experimental results are discussed to characterize the state of bonding.
Aerosol Deposition Method for Fabrication of Nano Crystal Ceramic Layer
Authors: Akedo Jun
Published: March 2009

Aerosol deposition method (ADM) for shock-consolidation of fine ceramics powder to form dense and hard layers is reported. Submicron ceramic particles were accelerated by gas flow in the nozzle up to velocity of several hundred m/s. During interaction with substrate, these particles formed thick (10 ~ 100 µm), dense, uniform and hard ceramics layers. Depositions were fulfilled at room temperature. Every layer has polycrystalline structure with nano-meter order scale. The results of fabrications, microstructure, mechanical and electrical properties of oxides (α-Al2O3; Pb(Zr0.52,Ti0.48)O3 etc.) and non-oxides materials are presented.
Cu-Based Metallic Glass Matrix Composites with High Ductility
Authors: Kim Yu Chan , Kim Do Hyang , Lee Jae Chul
Published: March 2009

A composite microstructure consisted of µm-scale Ta-rich solid solution particles
distributed in the bulk metallic glass matrix was successfully obtained by injection casting of the (Cu 60Zr 30Ti 10) 95Ta 5 alloy into a copper mold. The (Cu 60Zr 30Ti 10) 95Ta 5 bulk metallic glass matrix composite shows compressive strength of 2320 MPa and, in particular, a significantly improved plastic strain to failure of about 14.5%. The remarkable ductility improvement in the (Cu 60Zr 30Ti 10) 95Ta 5 composite could be explained by the presence of the highly ductile Tarich particles.
Preparation and Characterization of IZO Transparent Conducting Films by the Sol-Gel Method
Authors: Kim Chang Hyun , Lee Jin Hong , Park Byung Ok
Published: March 2009

Indium-zinc oxide (IZO), with Zn/(Zn+In)=0.33 - 0.78, films were deposited by the sol-gel method. Effects of Zn/(Zn+In) atomic ratio and annealing temperature on the structural, electrical and optical properties of IZO thin film were investigated. Films of Zn/(Zn+In)=0.33 prepared at 600°C had the lowest resistivity value, 4.48X10 -2 Ω cm (carrier concentration=3.83X 1018 cm-3 and mobility=25.54 cm2/Vs), and the structure of these films matched that of Zn2In2O5 film. Average optical transmittances of all films were above 80% in the visible range. The highest
average transmittance was observed at Zn/(Zn+In)=0.5, with 86.8% in the visible range.
Effect of UV Illumination on Deposition of Low-k Si-O-C(-H) Films by PECVD
Authors: Lee Heon Ju , Yang Chang Sil , Choi Chi Kyu
Published: March 2009

The characteristics of plasma are important for the deposition of SiOC(-H) low dielectric thin film. The effect of UV light illumination on the plasma parameter in the capacitive coupled plasma chemical vapor deposition (CCP-CVD) system is investigated. The electron density is almost not changed, but the electron temperature decreases by UV light illumination. The deposition rate increases and the dielectric constant of the film is lowered with UV light.
Alternating Magnetic Field Crystallization of Amorphous Si Films
Authors: Kang Ku Hyun , Lee Sung J. , Nam Seung Eui , Kim Hyoung June
Published: March 2009

We propose a new method for lower process temperature and shorter process time of SPC. This method involves the induction of high frequency alternating magnetic field during crystallization annealing, referring this process as Alternating Magnetic Field Crystallization, AMFC. The processed films were characterized using UV spectroscopy to determine the incubation time, Raman spectroscopy for the degree of crystallization. We found that the kinetics of crystallization was greatly enhanced by alternating magnetic field. When we crystallized, in the case of SPC, annealing time is over 14 hours at 570°C. But in the case of AMFC, annealing time is only
20minutes at the same temperature.
Investigation on γ-Channel Widening during Uniaxial Creep Test of a Ni-Base Single Crystal Superalloy
Authors: Jin Tao , Liu L.R. , Zhao Na Ru , Wang Zhi , Sun Xiao Feng , Guan Heng Rong , Hu Zhuang Qi
Published: March 2009

Investigation of γ -channel widening behavior in a nickel-base single crystal superalloy during uniaxial tensile creep tests was carried out. Scanning electron microscopy (SEM) was adopted to reveal the microstructural evolution of γ -channel and the dimension of γ -channel. It was found that different tests condition such as temperature, time and stress in tensile creep tests all influenced the γ -channel widening behavior, and a parabolic rate law governs the mean increase value of γ -channel width. The stress and temperature enhanced the γ -channel widening. The γ -channel widening was the result of directionally diffusion of multiatom.
Tensile Deformation Behavior of M963 Cast Nickel-Base Superalloy
Authors: Sun Xiao Feng , Yin Feng Shi , Guan Heng Rong , Hu Zhuang Qi
Published: March 2009

The tensile deformation behavior of M963 superalloy treated by various heat
treatments has been studied at both room and high temperature (1173K). The result shows that the alloy treated by the standard solution treatment at 1483K for 4h followed by air-cooling has low ductility especially at 1173K. The additional aging treatment at 1123K for 16h followed by furnace cooling can recover the ductility of the alloy at 1173K, but further decrease its room temperature ductility. The TEM observation shows that the deformation mechanism varied with both the testing temperature and heat treatment. Finally, the mechanism of the aging treatment
on the deformation behavior of the M963 superalloy is discussed.
Texture of Electrodeposited Ni Films
Authors: Kim In Soo , Sung Dong Young , Park Byung Hyun , Lee Min Gu
Published: March 2009

Electrodeposited Ni films were produced by using four types of electrodeposition methods, direct current without additive (DC), direct current with additive (AD), square pulse without additive (SP) and square pulse with additive (AS). The <100> texture was obtained by using the DC method at about 20 °C and by using the AD and the AS methods at about 80°C. The <110> texture was obtained by using the DC and the SP methods at about 80 °C. When using the AS method, the surface roughness of Ni deposit was lower than that of Ni deposits after using the other electrodepositon methods and the microstructure of Ni deposits showed nanocrystalline grain size. The <100> textures of Ni deposits using the DC and the AS methods remained unchanged after the recrystallization process. The <110> texture of Ni deposits using the SP method at about 80 °C changed to < 3 1 0>
orientation after the recrystallization process.
Ultrasonic Nondestructive Evaluation of the Creep Damaged IN738LC Superalloy
Authors: Byeon Jai Won , Song J.H. , Kwun S.I.
Published: March 2009

It was attempted to evaluate nondestructively the creep damaged IN738LC Ni based
superalloys with different degree of rafting using ultrasonic wave. Microstructural parameters (length and width of γ' precipitates) and ultrasonic attenuation were measured in order to clarify the relationship between them. Both the mean length of γ' precipitates and the ultrasonic attenuation increased with creep time. Ultrasonic attenuation was found to have a linear correlation with the mean length of γ' precipitates. It is suggested that the ultrasonic attenuation can be used as a
potential nondestructive parameter for assessing the degree of creep damage of IN738LC superalloy.
Mechanical Property of Single Phase Co-Ni-Cr-Mo Based Superalloy Produced by Cold Working and Recrystallization Heat Treatment
Authors: Sung Jun Kyung , Hong Gil-Su , Kim Won Yong , Kim Mok Soon , Hwang Sun Keun , Chiba Akihiko
Published: March 2009

Mechanical property of carbon-free Co-Ni-Cr-Mo based superalloy was investigated at room temperature and at 943 K. Cold working and subsequent recrystallization heat treatment was carried out to produce an equiaxed grain structure. The average grain size was controlled to 28 and 238 µm in order to understand the effect of grain size on mechanical property and flow behavior. At room temperature and 943 K, 0.2% offset yield strength increased with decreasing grain size to exhibit grain size dependence. At 943 K, a specimen with the average grain size of 28 µm showed
higher yield strength than that obtained with a specimen having the average grain size of 238 µm. A steady-state like behavior leading to an extensive ductility was observed in the fine-grained specimen. {111}<112> deformation twinning was found to correlate with the steady-state like behavior in the true stress-true strain curve. It was suggested that grain refinement is favor to enhance the fracture strength and allow the deformation twinning to occur.
Thermomechanical Behavior of Al-Mg-Si Alloys at the Elevated Temperature
Authors: Kwon Yong Nam , Lee Young Seon , Lee J.H.
Published: March 2009

Thermomechanical behavior of Al-Mg-Si alloys has been studied to investigate the effect of microstructural features such as pre-existing substructure and distribution of particles on the deformation characteristics. The controlled compression tests have been carried out to get the basic information on how the alloy responds to temperature, strain amount and strain rate. Microstructural features after forging have been discussed in terms of the thermomechanical response of Al-Mg-Si alloys. As already well mentioned, we have found that the high temperature deformation of Al-Mg-Si brought the recovered structure. However, the abnormally large grains seems to occur in a certain condition as a result of deformation assisted grain growth, which means that hot forging of Al-Mg-Si alloys could lead to the undesirable microstructures and the consequent mechanical properties such as fatigue strength.
Tensile Deformation and Fracture Behavior of a Commercial Al Alloy with Nano-Sized Grains
Authors: Chang Si Young , Seo Sang Ho , Lee Seong Hee , Kang Chang Seog , Hong Sung Kil , Shin Dong Hyuk
Published: March 2009

The nano-structure in the commercial 5083 Al alloy was introduced by the equal channel angular pressing technique. The nano-sized grains of ~300 nm were obtained after 8 ECAPs at 373 K and 473 K. It was also obvious that much improvement in strength was obtained at lower pressing temperature, 373 K, than 473 K. In particular, there were mainly two different tensile characteristics; one was that the strength in the alloy ECA pressed at 373 K was much higher than that of as-annealed alloy but the elongation to failure was significantly smaller, while, in case of pressing at 473 K, the improvement in strength was found without sacrificing much of the elongation. The other was that the work hardening with increasing the amount of deformation was found in the alloy ECA pressed at 473 K. These tensile deformation characteristics were analyzed based on the observations of microstructure by TEM and fracture surface by FE-SEM.