bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of Anomalous Interface Effects by Localization of Solute Redistribution in Thin Interface Phase-Field Modeling of Solidification
Authors: Kim Won Tae , Kim Seong Gyoon
Published: March 2009

A phase field model for alloy solidification was developed to suppress the anomalous
interface effects such as enhanced surface diffusion, chemical potential jump and surface stretching by localizing the solute redistribution into a narrow region within the phase-field interface. Application of this model to a free dendritic growth in an undercooled liquid yields quantitatively the same results as previously reported anti-trapping model. By localization of the solute redistribution into a region of single grid spacing the anomalous interfacial effects can be effectively suppressed. This model can be used for quantitative phase field calculation with an enhanced computational efficiency.
Numerical Simulation on the Solidification of ZA27 Alloy by a Two-Phase Flow Model
Authors: Zhang Zhan Ling , Yang Liu Shuan , Ni Feng
Published: March 2009

ZA27 alloy solidifies in the way of paste-solidification, and results in gravity segregation. The two-phase flow model was developed on the basis of the solidification characteristic of the ZA 27 alloy. And the governing equations of the solidification process were differentiated and computed in a 3-D cylindrical coordinate system through a heat and fluid simulation software package
(PHOENICS). The computation of the concentration field indicated a segregation of Al, and is in good agreement with the experiments. This model could simulate the convection and the gravitational segregation during the solidification.
Study on Effect of Technical Parameter on Fluid Flow and Solidification in Steel Strip Roll-Casting Process
Authors: Yang Jian Wei , Du Yan Ping , Sun Binyu
Published: March 2009

A 3-D coupled numerical model for flowing distribution and temperature distribution in twins strip roll-casting process is developed, and the influence of technological parameter on roll-casting process is studied. As a result, lower superheat can get more homogeneity structure in thickness direction, but the metal will solidify in the casting system if the superheat is too low, which doesn’t benefit the slag
inclusion floating up. When the velocity is between 6m/mim and 8m/min, the end-point will be at 2~8mm above the anastomotic point. The model can provide the theory to the control on strip roll-casting process.
Mathematical Simulation of Different Argon Blowing Style in Ladle Furnace
Authors: Ren San Bing , Fan Jun Fei , Huang Zong Ze , Chen Yi Sheng , He You Duo
Published: March 2009

In the present paper, applied the experiential correlation, the gas holdup and distribution of two phase zone which formed by argon blown were determined. The flow variables of molten steel and turbulence parameters in the Ladle Furnace were estimated utilizing the results of frontal calculation and through numerically solution momentum Navier-Stokes equation in conjunction with k-εturbulence model. Several different spray styles including blowing through single hole, double holes, top lance were simulated and compared in this project.
A Numerical Analysis on the Dissimilar Channel Angular Pressing Process by Rolling
Authors: Huh Moo Young , Choi Hyoung Jin , Ok J.H. , Hwang Beong Bok , Kang Bok Choon
Published: March 2009

The dissimilar channel angular pressing (DCAP) process by rolling was numerically modeled and analyzed by the rigid-plastic two-dimensional finite element method in order to optimize the strain state of the DCAP process. Three distinct deformation mechanics during DCAP by rolling includes rolling, bending, and shearing. AA 1100 aluminum alloy was selected as a model material for the analysis of DCAP process. Difference in the friction conditions between the upper
and lower roll surfaces led to large variation of shear strain component throughout the thickness of sample. Strain accompanying bending turned out to be negligible because of a large radius of curvature by relatively large roll diameter. The concentrated shear deformation was monitored at the corner of the DCAP-channel where the abrupt change in the direction of material flow occurred. The
strain state at the upper and lower surfaces was observed to vary strongly from that of the center layer of the sheet.
Cold Rolling Technique for Eliminating Cutting Process in Manufacturing Precise Product Using Non-Heat-Treated Micro Alloys
Authors: Choi Seo Gou , Yoon Duk Jae , Lee Geun An , Lee Hee Woong , Na Kyoung Hoan
Published: March 2009

In general micro alloy steel have the higher strength relative to conventional steels, which limits the utilization of conventional plastic forming processes. Incremental forming processes are more suitable for cold forming of such a high strength material. In particular, cold cross wedge rolling (CWR) can be a potential tool to fabricate axi-symmetric components with multi steps using high strength micro alloy steel. Obviously, optimization of die shape design is a crucial factor to apply cold
cross wedge rolling to micro alloy steels. In this regards, a simulation-based process design using an elasto-plastic FEM has been carried out in order to obtain an optimum die shape for cold cross wedge rolling in this paper. Analysis results provided that the stretching angle and the shoulder angle at knifing and guiding zones were significant parameters for the stable forming process. It was
demonstrated that proper stretching and shoulder angles reduced an excessive slip between a work piece and die in CWR process despite the condition of the low friction coefficient.
Forming Technology for Cold Forging Processes of Ball Stud Using Non-Heat-Treated Cold Forging Materials
Authors: Lee Geun An , Choi Seo Gou , Yoon Dong-Jin , Lee Hee Woong , Na Kyoung Hoan
Published: March 2009

A microalloyed (MA) forging steel is non-heat-treated materials that have been replacing for conventional quenched and tempered (Q/T) structural steels since the MA forging steels are very cost-effective compared with Q/T steels for the production of automotive parts. However, due to a high strength and low elongation, it has been difficult to apply the MA cold forging steel to the ball stud for automobile. In this study, finite element analyses were carried out to investigate the forming
loads, the stress and strain distributions of the workpiece in the cold forging processes of the ball stud using the MA cold forging steel. Compression test at room temperature and fatigue test were also performed to obtain the flow stress and fatigue life, respectively. From these results, it was found that the fatigue life was greatly affected by the strength in the neck region of the ball stud and the cold
forging processes should be designed to improve the fatigue life of the ball stud used the MA cold forging steel.
Numerical Simulation of Distortion Control by Static Thermal Tensioning in Welding of Thin Aluminum Alloy Plates
Authors: Guo Shao Qing , Xu Wen Li , Yuan Hong , Gu Wei Hua , Tian Xi Tang
Published: March 2009

Residual distortion is a serious problem associated with welding thin aluminum alloy
plates. As a distortion control technique static thermal tensioning has been used for many years. Owing to the insufficient understanding of its control mechanism and parameter influence, its application cannot always yield ideal results. So finite element analysis was performed. Based on the simulation results, presetting a saddle-shaped temperature field during welding can significantly reduce longitudinal inherent shrinkage strain in the weld and its adjacent zones, which will then
reduce residual stresses and distortion. Temperature difference between the side and central zones is a key parameter and with its increase distortion reduction can be improved. Postweld thermal tensioning can cause certain plastic tensioning, but its effect cannot compare to that of a preset one. These numerical simulation findings were verified finally by experimental investigation.
A Study on the Manufacturing Process Sequence of Power Assisted Steering Part
Authors: Hwang Beong Bok , Ham B.S. , Min Kyung Hoon , Choi Hyoung Jin , Lim Joong Yeon
Published: March 2009

The manufacturing process sequence of a power steering worm gear blank is analyzed. The conventional process sequence for manufacturing power assisted steering (PAS) part contains three distinctive operational stages such as indentation, extrusion, and upsetting, which were originally designed by forming equipment experts. Process conditions such as reduction in area, semi die angle
and upsetting ratio are carefully considered to prevent from internal or geometrical defects. The simulation results of the conventional forging process are summarized in terms of deformation patterns, load-stroke relationships and die pressures along the interface for each operational stage. Close investigation of simulation results for current forming process leads to a new process sequence in which the number of operation are reduced into just one operation. Comparisons between the existing and proposed processes are made in terms of maximum force requirement, required forming energy, and process time, respectively. Experiment has been performed to confirm that the proposed process could be applied to replace the existing conventional process sequence and proved the new process to be a safe process sequence for manufacturing PAS part.
Mechanical Characteristic of Flowing Solidification under the Extrusion for the Mixture of the Liquid Aluminum with Sillimanite Particles
Authors: Chen Wei , Sun Chang Qing , Li Yun Liang
Published: March 2009

: According to the theory of liquid metal forging and liquid metal extrusion, a new kind of fabricating method for particles reinforced metallic matrix composite was put forward by author. In this paper, the extrusion process to semisolid thick liquid after the mixture was studied by means of the theoretical analysis and experimental methods. Mechanical characteristics of solidification during flowing and plastic deformation during solidification of the composite were found. So the base was built up for selecting technology parameters and for building a stabile process
The Prediction of Failure Pressure of Gas Pipeline with Multi Corroded Region
Authors: Lee Y.K. , Kim Young Pyo , Moon M.W. , Bang Woong Ho , Oh Kyu Hwan , Kim Woo Sik
Published: March 2009

The failure assessment for the defects in multiple corroded region has been considered with the real-size pipeline burst tests and the associated Finite Element Method. The corroded gas pipeline made of X65 steel with various types of artificially machined pits has been used for a number of series of burst tests on gas pipeline. The failure pressures for the designed multiple corroded defect on gas
pipelines have been measured by using in-situ burst testing and classified with respect to each designed defect sizes - length, width and depth - and distance between defects. The result from the experiments has been modeled and compared with Finite Element Method. As the result of FEM simulation, the failure pressure in multiple defects is lower than that in single defect, and closer to failure pressure in single defect of total length of defects in multiple defects as the distance between
each defect is closer.
Corrosion of Al-Cu-Fe-Cr Quasicrystalline Coating
Authors: Kang Yong Wang , Zhou Chungen , Gong Sheng Kai , Xu Hui Bin
Published: March 2009

Al-Cu-Fe-Cr quasicrystalline coating was deposited on a substrate of stainless steel by low-pressure plasma spraying (LPPS) method. The corrosion behavior of such coating was studied by polarization in 1mol/l H2SO4 and 0.1mol/l NaOH solutions at room temperature. The polarization curve shows that LPPS Al-Cu-Fe-Cr quasicrystalline coating can turn to passive state both in 1mol/l H2SO4 solution and in 0.1mol/l NaOH solution. The corrosion resistance of the coating is poorer than that of bulk quasicrystal in 0.1mol/l NaOH solution. Moreover, in strong acid
solution LPPS Al-Cu-Fe-Cr quasicrystalline coating has more corrosion resistance than 1Cr18Ni9Ti in some potential range ranging from -200mVSCE to -35mVSCE, but in strong alkaline solution the corrosion resistance of the coating is poorer than 1Cr18Ni9Ti.
The Electronic Characteristics of IrSi Thin Films
Authors: Ma Xi Ying
Published: March 2009

The Schottky barrier height (SBH) of IrSi nanometer thin films prepared by pulsed laser deposition at room temperature and annealed at 600 °C has been studied. The SBH of the sample is deduced from C-V and I-V data. These SBHs decrease with increasing measurement temperature.
Control of Nano-Precipitates in Age-Hardenable Aluminum Alloys and Their Mechanical Properties
Authors: Sato Tatsuo , Shoichi Hirosawa
Published: March 2009

The nano-scale precipitate microstructures and properties of age-hardenable aluminum alloys such as Al-Cu, Al-Mg-Si and Al-Zn-Mg alloys were investigated using conventional electrical resistivity and hardness measurements, TEM and 3D-AP techniques. To increase mechanical strength and ductility of the alloys nano-scale precipitates were effectively controlled by applying new type heat treatments and microalloying elements. In the initial stage of phase decomposition of the alloys containing microalloying elements several types of nanoclusters were formed and distinctly detected by the 3D-AP technique. These nanoclusters greatly affect the
nucleation of the subsequent precipitates and resultantly mechanical properties. In Al-Mg-Si and Al-Zn-Mg alloys complicated two-step aging behaviors were found to be originated in the positive or negative effect of the nanoclusters with different structures.
Influence of Nb on the Interface Structure of Tungsten Fiber Reinforced Zr-Based Bulk Metallic Glass Composites
Authors: Wang Mei Ling , Hui Xidong , Chen Guo Liang
Published: March 2009

Zr-based metallic-glass matrix composites, which are reinforced by continuous tungsten fibers, were prepared by melt infiltration casting. The interface structure was analyzed by using X-Ray diffraction, SEM and EPMA. The results illustrate that for the Zr55Al10Ni5Cu30 matrix composite, in addition to the interface diffusion, an interface eutectoid reaction between W fiber and Zr in the liquid state takes place and forms W5Zr3 phase at the interface during casting, the interface is included in Class Ⅲ system; but for (Zr55Al10Ni5Cu30)0.98Nb2 and Zr57Al10Ni12.6Cu15.4Nb5 matrix composite, the addition of Nb restrains the interface eutectoid reaction effectively, which may be attributed to reducing diffusion coefficient of Zr through the interface, and there is only a thinner diffusion layer at the interfaces, the type of interface is changed to the Class Ⅱ system
Scanning Anomalous Small-Angle Scattering as a Tool to Examine Welded Bulk Glass
Authors: Murase Isao , Kurosaki Ryoichi , Okuda Hiroshi , Ochiai Shojiro , Yokoyama Y. , Inoue Akihisa , Inoue Kanryu
Published: March 2009

Small-angle scattering measurements utilizing anomalous dispersion effect just below the Zr and Ni K edge have been made for welded Zr-based amorphous materials. The measurements were carried out at a bending magnet beam-line 40B of SPring8. A small and parallel X-ray beam generated at the third generation synchrotron is suitable for nanostructure mapping of heterogeneous materials,
whose structure varies with less than a millimeter scale. The remelted and heat-affected zones were examined for electron-beam welded Zr-Ni-Cu-Al alloys. Merits and the characteristics, as well as its present limitations of scanning small-angle scattering with a use of anomalous dispersion effect is discussed as a tool to examine microstructure in the spatially inhomogeneous materials in macroscopic scale as well as microscopic scale.
Glass-Forming Ability and Mechanical Properties of Fe-Ni-Zr-Si-B Bulk Glassy Alloys
Authors: Lee K.A. , Namkung J. , Kim Moon Chul
Published: March 2009

The effects of structural relaxation and partial crystallization on the mechanical property of the Ti40Zr29Cu9Ni8Be14 bulk metallic glass (BMG) have been investigated. The atomic structure of the as-cast Ti40Zr29Cu9Ni8Be14 metallic glass transforms into a more relaxed state at the temperature region of 452 –585 K, below the crystallization onset temperature of 631 K. Stable icosahedral phase
forms in the amorphous matrix by growth of the pre-existing nuclei in the amorphous matrix during first crystallization step. The compressive plastic strain of the as-cast Ti40Zr29Cu9Ni8Be14 BMG is 6.7 %, and decreases when the structural relaxation occurs. However, the plastic strain increases when a few nanometer size icosahedral phase particles form in the amorphous matrix by the partial
crystallization treatment.
Synthesis of Cu-Based Bulk Metallic Glass Matrix Composites by Warm Processing of Gas Atomized Powders
Authors: Lee J.K. , Kim H.J. , Yamasaki Michiaki , Kawamura Yoshihito , Bae Jung Chan
Published: March 2009

The bulk metallic glass matrix composite comprising Cu54Ni6Zr22Ti18 metallic glass
powder and ductile brass powder was fabricated by the warm process. The warm process was carried out by spark plasma sintering, which led to the homogeneous distribution of both phases of brass and metallic glass without pores. The metallic glass matrix composite material exhibits the same crystallization behavior of the metallic glass powder. A compressive strength of 1.0 GPa with a plastic strain of 3 % was obtained in the present metallic glass composite. The composite with
enhanced strength and ductility was successfully achieved by introducing a ductile phase in the hard bulk metallic glass.
Glass Forming Ability in Amorphous Ti50Cu35-xNi15Snx Alloys Prepared by Mechanical Alloying
Authors: Lin Chung Kwei , Hsu C.C. , Jeng R.R. , Lin Y.L. , Yeh C.H. , Lee Pee Yew
Published: March 2009

in the present study, amorphous ti50cu35-xni15snx (x=0~7) alloy powders were
synthesized by mechanical alloying technique. the amorphization behavior of ti50cu28ni15sn7 alloy powders was examined in details by scanning electron microscopy, differential scanning calorimeter, x-ray diffraction, and synchrotron x-ray absorption spectroscopy. the results show that fully amorphous powders formed after 7 hours of milling. The thermal stability of the Ti50Cu35-xNi15Snx amorphous powders was investigated by differential scanning calorimeter. The amorphous Ti50Cu35Ni15 powders (i.e., x=0) exhibit no glass transition behavior. However, the amorphous Ti50Cu35-xNi15Snx (x=3~7) powders were
found to exhibit a supercooled liquid region before crystallization. Amorphous
Ti50Cu28Ni15Sn7 alloy powders exhibits a wide supercooled liquid region of 61 K.
Grain Growth and Mechanical Properties of Nanograined Bulk Fe-25Ni Alloy
Authors: Wang Hong Bin , Wang Xiao Yu , Zhang J.H. , Hsu T.Y.
Published: March 2009

The grain growth and mechanical properties of nanograined bulk Fe-25at%Ni alloy
prepared by an inert gas condensation and in-situ warm consolidation technique were investigated. About 43% high temperature face-centered-cubic (FCC) phase and 57% low temperature body-centered-cubic (BCC) phase were observed in the sample at room temperature, which was significantly different from that of the corresponding conventional coarse-grained alloy. The in-situ
X-ray diffraction results show that the start and the finish temperature of BCC to FCC phase transformation are 450°C and 600°C, respectively. The isothermal grain growth exponent n from t k D D n n ¢ = − 1 0 1 for nanograined single FCC phase Fe-25at%Ni alloy is 0.38 at 750 °C . The mechanical properties changing with the grain size were studied by means of microindentation test.
Etching Mask Effect of the Nanoscratched Borosilicate Surface and Its Application to Maskless Pattern Fabrication
Authors: Youn S.W. , Kang Chung Gil
Published: March 2009

The purpose of this study is to suggest a maskless pattern fabrication technique using the combination of machining by Nanoindenter® XP and HF wet etching. Sample line patterns were machined on a borosilicate surface by constant load scratch (CLS) of the nanoindenter with a Berkovich diamond tip, and they were etched in HF solution to investigate chemical characteristics of the machined borosilicate surface. After the etching process, the convex structure was made. On the basis of this fact, some line patterns with convex structures were fabricated.
Softening Phenomenon during Compression Test in Nanograined Aluminum Alloys
Authors: Ko Se Hyun , Jang Jin Man , Lee Won Sik
Published: March 2009

Al-Mg and Al-Mg-Cu alloys are known well to reveal superplasticity in tension at high
temperatures. In this study, deformation behaviors of those alloys nanograined were investigated under compression test at room temperature. During plastic deformation softening phenomena occurred obviously in nanograined Al-1.5wt%Mg and Al-0.7wt%Mg-1.0wt%Cu alloys while slight strain hardening appeared in nanograined pure Al. These results suggest that the softening strongly
depends on composition of alloys. The softening takes place over strain rate range from 10-4 up to 10-1.
Interfacial Reaction and Strength of Dissimilar Joints of Aluminum Alloys to Steels for Automobile
Authors: Hirose Akio , Matsui Fumiaki , Imaeda Hirotaka , Kobayashi Kojiro F.
Published: March 2009

In the present study, we fundamentaly analyzed the interfacial reaction and evaluated the joint strength in dissimilar diffusion bonding of Al alloys to steels. The growth of the reaction layer consisting of FeAl3 and Fe2Al5 intermetallic compounds followed the parabolic growth low. The joints with 5000 series Al alloys had a higher growth rate of the reaction layer than the joints with A6061 Al alloy. The joints of A6061 Al alloy to HT980steel had the lowest growth rate of the reaction layer. The joint strength depended on the thickness of the reaction layer. The A6061 Al alloy/steel joints had the maximum joint strength at around 1µm of average reaction layer thickness.
A New Method for Bulk-Quantity Synthesis of Patterned Well-Aligned ZnO Nanowire Arrays
Authors: Xu X.Y. , Zhang Hui Zhao , Zhao Qiang , Chen Yun Fa , Xu Jian , Yu D.P.
Published: March 2009

Large area well-aligned ZnO nanowire arrays have successfully been synthesized on an unconventional substrate: stainless-steel mesh at a low growth temperature of 400oC. The as-grown ZnO nanowires have uniform diameters about 20 nm and a strong UV peak was observed in photoluminescence spectra. The growth method provides a novel way to produce high quality ZnO nanowire arrays, and can be also used to direct the controllable growth of other nanomaterials.
Large-Scale Synthesis of In2O3 Nanowires and Their Characterization
Authors: Zeng Fan Hao , Zhang X.
Published: March 2009

Large-scale single-crystalline In2O3 nanowires were successfully synthesized by simply evaporating the pure indium at 950ı. The as-synthesized products, characterized by XRD, SEM, and TEM, were pure, structurally uniform, and single crystalline with typical diameters of 10 to 100 nanometers and lengths of up to a few hundreds of micrometers. The growth mechanism of the nanowires also was discussed.
Raman Scattering and Photoluminescence Studies of Zn1-xMnxO Nanowires via Vapor Phase Growth
Authors: Chang Y.Q. , Chen Yi Zhi , Yu D.P. , Fang Z.L. , Li G.H. , Yang F.H.
Published: March 2009

In this paper, we investigated the Raman scattering and photoluminescence of Zn1-xMnxO nanowires synthesized by the vapor phase growth. The changes of E2(High) and A1(LO) phonon frequency in Raman spectra indicate that the tensile stress increases while the free carrier concentration decreases with the increase of manganese. The Raman spectra exited by the different
lasers exhibit the quantum confinement effect of Zn1-xMnxO nanowires. The photoluminescence spectra reveal that the near band emission is affected by the content of manganese obviously. The values of IUV/G decrease distinctly with the manganese increase also demonstrate that more stress introduced with the more substitution of Mn for Zn.
Microstructures and Thermal Stability of the Metastable-Phase Precipitates Formed in an Al-Cu Alloy
Authors: Son Sung Kyu , Takeda Mahoto , Endo Takao
Published: March 2009

The precipitation behavior in an Al-Cu alloy isothermally annealed at 373K～493K was studied, using the Vickers microhardness tests, Differential scanning calorimetry(DSC) and Transmission electron microscope(TEM) observations. An additional endothermic peak was found in DSC measurements which may be attributed to the θ″-phase independent from the formations of the G.P.(Ⅱ) and the θ′-phase at the aging temperatures. High resolution transmission electron
microscopy (HRTEM) revealed that the G.P.(Ⅰ) is formed at a very early stage of isothermal aging at 463K. Comparing the Vickers microhardness and TEM images, it was concluded that G.P.(Ⅱ) is mainly responsible for the peak hardness.
Synthesis and Characteristic of Cuprous Oxide Nano-Whiskers with Photocatalytic Activity under Visible Light
Authors: Yu Ying , Huang Wen Ya , Du Fei Peng , Ma Li-Li
Published: March 2009

A novel Cu2O nano-whiskers with diameter of 6 ~ 12nm has been synthesized with the method of chemical deposition by adding surfactant cetyltrimethylammonium bromide (CTAB) as a template. The structure of the nano-whiskers has been characterized with XRD, SAED, TEM and XPS. The results show that the nano-whiskers exhibit a well crystallized 1D structure about 300 nm in length, and they are self-assembled by Cu2O quantum dots. Under visible light, the degradation
efficiency of p-chloronitrobenzene with the Cu2O nano-whiskers as photocatalyst can reach 85.8%.
X-Ray Diffraction and Raman Scattering Study of Sr1-xBi2+yTa2O9 Nanoparticles
Authors: Zhou Yu , Ke Hua , Jia De Chang , Wang W. , Rao J.C.
Published: March 2009

Sr1-xBi2+yTa2O9 (x, y=0.2, 0) nanoparticles, synthesized by a sol-gel method, are investigated by X-ray diffraction and Raman spectroscopy. Large structure distortion shows the size effects in nanoparticles, which gives rise to the Raman bands broadening. The Bi content is the most important factor responsible for non-stoichiometric SrBi2Ta2O9 structure distortion and providing the larger ferroelectric spontaneous polarization and the higher Curie temperature. The stability of the crystal structure is discussed in consideration of inner compressive stress in
nanoparticles.
Preparation of Size Controllable MgO Nanoparticles via Reverse Microemulsion Method
Authors: Han D.Y. , Yang Huai Yu , Shen C.B.
Published: March 2009

Nanoparticles of MgO were successfully prepared in Triton X-100/n-hextnol/cyclohexane/water W/O microemulsion system. Basic preparation conditions were determined. TG-DTA showed that the proper calcination temperature was 450 oC. The nanoparticles were characterized by XRD and IR measurements in order to determine the crystal phase and component of the products. The morphological feature of the nanoparticles has been investigated by
TEM. The result of XRD pattern demonstrated that the particles were exactly indexed to a cubic rock salt structure of MgO. There are no organic or inorganic impurities appeared after 450 oC calcination. The result of TEM showed that the MgO nanoparticles were spherical and uniform. The UV-visible spectra demonstrated the phenomenon of absorption blue shift, which is the evidence
of quantum confinement effect, with the decrease of water/surfactant(R) value. Average size of the nanoparticles increased with increasing R value.
Characterization of Fe Based Nanopowders Synthesized by Gas Phase Synthesis
Authors: Choi Chul Jin , Kim Jin Chun , Yu Ji Hun , Kim Byoung Kee
Published: March 2009

Nanosized Fe based powders have been synthesized by both chemical vapor
condensation (CVC) and plasma arc discharge (PAD) processes. Fe, Fe-C and Fe-N nanopowders were successfully synthesized. The influence of experimental parameters on microstructures and phase composition of nanopowders was investigated. The prepared powders were nearly spherical
in shape and core-shell type in structure. Various kinds of Fe-C and Fe-N composite nanopowders could be synthesized by controlling the carrier gas and precursor decomposition temperature, etc.
Effect of H2 Gas on Carbon Nanotubes Synthesis
Authors: Chung Uoo Chang , Lee Deok Bo , Jeong Y.U. , Ha M.J. , Chung Won Sub
Published: March 2009

The effect of H2 gas during the carbon nanotubes (CNTs) synthesis with CO-H2 gas mixture was investigated using by mass measurement, and scanning electron microscopy (SEM). The maximum weight and yield of the synthesized carbon (C) were obtained when the mixture ratio of H2:CO was 3:7 and 9:1, respectively. In case of 100% carbon monoxide (CO) without hydrogen (H2)
addition, the weight of carbon increased, but CNTs were not observed. The CNTs were formed when the contents of H2 reaches at least 10%, and their structures became more distinct with an increase of H2 addition, and then the shapes of CNTs were more thin and straight. When the contents of H2 was 80% (H2:CO = 8:2), the shapes and growth of CNTs showed an optimal condition. On the other hand,
when the contents of H2 was higher than the critical value, the shapes of CNTs became worse due to transition into inactive surface of catalyst. It was found that H2 played a major role in the shapes and structures of CNTs.
Preparation and Microwave Permittivity of Nano-Sized Si/C/N Powder
Authors: Liu Xiao Kui , Zhou Wan Cheng , Luo Fa , Zhu Dong Mei
Published: March 2009

Nano-sized Si/C/N powders are prepared from hexamethyldisilazane ((CH3)3Si)2NH) by chemical vapor deposition (CVD) at different pyrolysis temperatures from 900°C to 1200°C. The as-formed Si/C/N nano powder is amorphous, and after controlled heat-treatment, SiC crystals formed. The composition of the Si/C/N powders prepared at different conditions is analyzed and the result shows that the nitrogen content of the Si/C/N powder is related to the synthesizing temperature. Si/C/N powders heat-treated at different temperatures are mixed with paraffin wax and the microwave permittivity of the mixture is measured. The result shows that the e¢, e², and the dissipation factor tg d ( e²/ e¢) of the mixture are high at the frequency of 8.2~12.4GHz, and the
nitrogen content and the degree of crystallization have influence on the microwave permittivity. We believe that the high value of e¢, e² ,and tg d are due to the dielectric relaxation as the result of nitrogen atoms doped in silicon carbide lattice.
The Field Emission Properties of Sub-Micrometer Diamond Tube Arrays Fabricated by Focused Ion Beam Pattern
Authors: Gu Chang Zhi , Jin Ai Zi , Wang Z.L. , Li J.J.
Published: March 2009

Sub-micrometer diamond tube arrays are formed on freestanding diamond film via
focused ion beam pattern technology and chemical etching method. First, the sub-micrometer holes are fabricated on Si substrate by using FIB milling method. Then, diamond film is grown by hot filament chemical vapor deposition method on patterned Si substrate. By controlling the deposition parameters, the diamond can be grown along the wall of holes and the diamond tubes in sub-micrometer scale are formed. Finally, Si substrate is etched by chemical etching method and the
diamond tube arrays are fabricated on a freestanding diamond film. Scanning electron microscopy and Micro-Raman spectroscopy measurements are performed to characterize the structure and phase purity of diamond tubes. The electron emission properties from the diamond tube arrays are studied, the result presents that the enhanced emission property can be obtained from diamond tube
arrays.
Evolution of Stress-Induced Surface Damage and Stress-Relaxation of Electroplated Cu Films at Elevated Temperatures
Authors: Hwang Soo Jung , Koike Junichi , Joo Young Chang
Published: March 2009

The reaction induced phase separation aimed for the distribution of nano-structured particles has been investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) in ternary Ti-Si-N film via N+ implantation. The fabrication of Ti-20at%Si film has made on Si substrates by ion beam sputtering (IBS), and then N+ implantation with 50 keV has been conducted on these films. The selected area electron diffraction (SAED) from as-deposited film shows amorphous Ti-Si. As-deposited Ti-Si film exhibited high stability even for the heat treatment at 773K for 3600s. N+ implantation induced the direct formation of nano crystalline of fcc-TiNx within the Ti-Si film. The XPS depth profiling and chemical shift suggest that the preferential nitriding of Ti accompanied with the segregation of SiNx occurred during N-implantation.
Computer Simulations on Mechanical Properties of Molecular Deposition Film
Authors: Lan Hui Qing , Li Decai , Zhang Si Wei
Published: March 2009

The mechanical properties of the molecular deposition film deposited on an Au substrate are studied in the theory for the first time. Firstly, the quantum mechanics have been used to calculate the structure parameters and potential parameters of the molecular deposition film. Secondly, molecular dynamics simulations have been used to study indent process of the molecular deposition film with the action of Au tip. The results showed that an obvious jump to contact appears during the Au tip approaches the molecular deposition film; furthermore, the tilt angle and
load of the molecules near the tip have the same tendency of hysteresis, which may be caused by the adhesive force between the tip and the molecular deposition film.
Effects of Annealing on the Structure and Photoluminescence of Amorphous SiC:Tb Films Deposited on Porous Silicon
Authors: Xu D.Y. , Liu Yan Ping , Chen Z.Y. , He Z.W. , Liu Xing Qin , Wang Y.Y.
Published: March 2009

Tb-doped silicon carbide (SiC:Tb) films were deposited on porous silicon (PS) substrates by rf co-sputtering. The prepared films were annealed in N2 atmosphere at different temperature from 500-1000 °C. The effects of annealing on the structure and photoluminescence (PL) characters of the films were investigated by Atomic force microscopy (AFM), Raman, Fourier transform infrared spectroscope (FTIR) and fluorescence spectrometer. The SiOx layer at the SiC:Tb/PS
interface was destroyed as the annealing temperature increasing, and the oxygen-deficiency centers (ODCs) increased. The SiOx layer was restructured at higher annealing temperature and the ODCs decreased. This is the reason of origin and changing of UV band in PL spectra. The visible band origins from Tb3+, and is stable with annealing temperature.
Laser Induced Preparation of Flexible Cold Cathode and Its Electron Emission Properties
Authors: Ma Hui Zhong , Zhang Lan , Zhang Jun Jie , Du Yun Hai , Yao Ning , Zhang Bing Lin
Published: March 2009

A flexible carbon thin film was prepared by laser induced when phase changing of
polyimide thin film. There is no substrate for this thin film. It could be curved at any angle. The electron emission properties of the prepared thin film were measured by a diode mechanism; the thin film was used as a cathode and indium-tin-oxide (ITO) glass as an anode. The turn-on field of the thin film was about 2.1 V/µm. The current density of the thin film was about 150 µA/cm2 at the electric
field of 4.5 V/µm. The electron emission measurements indicate that the thin film could be a good candidate electron emission material in flat panel display or be used as other electron source. The morphology and structure of the thin film were investigated by optical microscope and Raman spectroscopy.
Microstructure and Optical Properties of (Zr0.8, Sn0.2)TiO4 Thin Films Grown on Si(100) Substrates by a Sol-Gel Process
Authors: Cheng Wen Xiu , Ding Ai Li , Qiu Ping Sun
Published: March 2009

Amorphous and crystalline (Zr0.8,Sn0.2)TiO4 （ZST） thin films deposited on Si(100) substrates have been prepared by a sol-gel process. The crystal structure and surface morphologies of the thin films have been studied by X-ray diffraction and atomic force microscopy. The crystalline ZST films on Si(100) substrata with a (111) orientation The refractive index n and extinction coefficient k of the amorphous and crystalline thin films were obtained by spectroscopy ellipsometry as a function of phone energy in the range from 0.7 to 5.4 eV. The
absorption edges for amorphous and crystalline ZST are 3.83 and 3.51eV of indirect–transition type respectively.
Granular Structure and Magnetic Properties of FePt/C Films
Authors: Zhen Cong Mian , Zhai Xiao Xia , Pan Chengfu , Nie Xiangfu
Published: March 2009

FePt/C mutilayer films were successfully prepared by using RF and DC magnetron
sputtering system. FePt nanoparticles embedded in a C matrix were formed by consequently annealing. X-ray diffraction (XRD) results show the degree of atomic ordering of the L10 structure increases with higher temperature annealing. Room temperature magnetic measurements reveal that in-plane coercivity HC, and squareness Mr/MS depend on the thickness of carbon layer. Relatively
High HC (3245.1Oe) and squareness (0.67) were obtained when the thickness of C layer is 2.0 nm. The carbon layer not only isolates the FePt grain, but also suppresses the growth of fct FePt grains. When the thickness of carbon layer is 2.0 nm, the FePt grain size decreases down to ~20 nm measured by Scan Probe Microscope (SPM). Interactions between particles can be tuned to near
zero when we select the proper thickness of C layer.
Preparation of Oriented Fe2O3 Film on Glass/Si Substrate by Atmospheric MOCVD
Authors: Cheng Jin , Zhang Yue
Published: March 2009

In recent years, much work has been done on microwave absorbing materials, and
anisotropy magnetic materials are expected to have excellent microwave absorbing properties. We have prepared well-aligned ZnO whiskers on glass substrate by atmospheric MOCVD. In the present work, Fe2O3 film is deposited by this technique. The phase composition, orientation and morphology of deposited products are studied by XRD and SEM. The effects of the deposition
conditions (such as vaporizing temperature, substrate temperature, distance from nozzle to substrate, and carrier gas flux) are investigated. The optimal conditions for the preparation of orientated Fe2O3 film and even well-aligned whisker array are discussed.
The Influences of Depositing Angles on TbFe Film Magnetic and Magnetostrictive Characteristics
Authors: Jiang Hong Chuan , Zhang Wan Li , Peng Bin , Zhang Wen Xu , Yang Shi Qing
Published: March 2009

In this paper, the influences of depositing angles on TbFe film magnetic and
magnetostrictive characteristics were discussed. TbFe films were deposited by DC magnetron sputtering. With the decrease of depositing angles from 900 to 150, TbFe film in-plane magnetization measured at 1600kA.m-1 external field is greatly increased. With the decrease of depositing angles from 900 to 150, the magnetostrictive saturation field is decreased. TbFe film in-plane magnetostriction is improved when depositing angles are changed from 900 to 150. Magnetic domain
structures detected by MFM indicates that film easy magnetization direction is gradually changed from perpendicular to parallel with the decrease of depositing angles. The variation of film magnetic and magnetostrictive performances can be explained by the oblique anisotropy associated with columnar grain morphology of the films.
Transport Properties in YBa2Cu4O8/La0.67Ca0.33MnO3 Multilayers
Authors: Zhao K. , Zhang L. , Liang B.L. , Wu C. , Feng J.F. , Wong H.K.
Published: March 2009

Transport properties of YBa2Cu4O8 (YBCO)/La0.67Ca0.33MnO3 (LCMO) multilayers were studied. The metal-semiconductor transition temperature shows an oscillatory behavior with a period ~ 12 nm. In contrast to that for LCMO films, the magnetoresistance ratio for multilayers is enhanced and strongly depends on the thickness of the YBCO layer. These results imply that the magnetic spin
interaction between the LCMO layers may exist through the normal-conductive YBCO layer.
Development of Horizontal Reheating System for Semi-Solid Die Casting and Its Microstructure Evaluation
Authors: Seo P.K. , Kim Byung Min , Kang Chung Gil
Published: March 2009

The parts manufactured by die casting process usually contain liquid segregation and porosities. To solve these problems, the semi-solid forming process has been applied. The process enables material in the semi-solid state to be completely filled, and parts with the complicated shape to be fabricated by applying relatively low pressure. This process is necessary in order to control the microstructure of the billet as well as to achieve the desired semi-solid billet state. In this study, a horizontal high-frequency induction heating device which can be fabricated by semi-solid forming irrespective of a billet's size was developed. A globular structure of the reheated billet and a billet's temperature distribution during the reheating process for A356 were investigated.
High-Quality Semiconductor Carbon-Doped β-FeSi2 Film Synthesized by MEVVA Ion Implantation
Authors: Li Xiao Na , Dong Chuang , Xu Lei
Published: March 2009

Carbon-doped b-FeSi2 films synthesized by ion implantation are investigated with the
aim to fabricate high-quality semiconducting b-FeSi2 layer on silicon substrate. According to transmission electron microscopy cross-section observations, carbon-doped films, with homogeneous thickness and smooth b/Si interface, have higher quality than binary Fe-Si films. In particular, annealing at 500 °C ~ 700 °C leads to the formation of a flat and continuous b-type silicide layer. Improved thermal stability of the b phase is also found. Optical emission spectroscopy measurements show that the doping influences only slightly the band gap values.
Effects of Heat Treatment on Microstructure of Sputter Deposited TiNiPd Film on Si Wafer
Authors: Qian Shi Qiang , Wu Jian Sheng
Published: March 2009

Amorphous thin Films of Ti51.78 Ni22.24Pd25.98 alloys were deposited onto 2 inch diameter n-type (100)Si wafer by r.f. magnetron sputtering. The crystallization temperature from an amorphous state to crystallization of free-standing thin film was found to be 553.1oC, but that of non-free-standing thin film on Si wafer was found to be higher from X-ray diffraction experiment. The film heated 1 h at 550 oC was partly crystallized but at 650 oC was almost whole crystallized. The film heated 1 h at 750 oC quite crystallized and some precipitation appear. Heated 50 h at 450
oC before crystallization the films would be accelerate B19' but restrain B19 formation in succeeding heat-treatment.
Atomic and Electronic Structures of Cu/Sapphire Interfaces by HRTEM and EELS Analyses
Authors: Sasaki Takeo , Mizoguchi Teruyasu , Matsunaga Katsuyuki , Tanaka Shingo , Yamamoto Takahisa , Kohyama Masanori , Ikuhara Yuichi
Published: March 2009

Interfacial atomic and electronic structures of Cu/Al2O3(0001) and Cu/Al2O3(11
＿ ,20) prepared by a pulsed-laser deposition technique were characterized by high-resolution transmission electron microscopy (HRTEM) and electron energy-loss spectroscopy (EELS). It was found that both systems have O-terminated interfaces, irrespective of different substrate orientations. This indicates
that Cu-O interactions across the interface play an important role for the Cu/Al2O3 systems.
Effect of Grain Boundary Character Distribution on Stress Corrosion Cracking Behavior in Austenitic Stainless Steels
Authors: Ishibashi Ryo , Horiuchi Toshiaki , Kuniya J. , Yamamoto M. , Tsurekawa Sadahiro , Kokawa Hiroyuki , Watanabe T. , Shoji Tetsuo
Published: March 2009

The effect of grain boundary character distribution (GBCD) on intergranular stress corrosion cracking (IGSCC) in austenitic stainless steels in high temperature water was verified experimentally. GBCD control using the strain annealing method increased the fraction of low- S coincidence site lattice (CSL) boundaries and the segmentalized network of random grain boundaries in austenitic stainless steels. The fractions of low- S CSL boundaries of GBCD
controlled steels were 75–85%, while those of uncontrolled steels were 60–70%. Creviced bent beam tests were conducted at 561 K in pure water containing 8 ppm dissolved oxygen for stress corrosion cracking (SCC) evaluation. The tests revealed that GBCD control suppressed IGSCC initiation or propagation and that cracks were predominantly propagated along random grain boundaries. It is considered that induced lower- S CSL boundaries result in high resistance to
IGSCC.
In Situ HREM Studies of Grain Boundary Formation during Solidification of B-Doped Silicon
Authors: Fukushima Hiroshi , Kuchiwaki Isamu , Hirabayashi Takahiro
Published: March 2009

In situ high-resolution transmission electron microscopy experiments were applied to
examine the nano-scale solidification process of boron-doped silicon from the liquid state. Fine particles of the specimen were first heated up to the melting temperature using a TEM heating-holder, and then gradually cooled across the melting temperature. The specimen was observed nearly along [001] direction. The lattice fringe of (220) plane was observed during solidification, and this part
combined with the other liquid part to make a twist boundary. The angle between the (220) planes of these two crystal grains was close to the rotation angle of the (001) Σ5 twist boundary.
Evolution of Annealing Textures and Microstructures in AA 3103 after Cold Rolling and Repeated Shear Deformation
Authors: Huh Moo Young , Lee J.P. , Lee Jae Chul , Park Jong Woo , Chung Young Hoon
Published: March 2009

The evolution of annealing textures and microstructures in the aluminum alloy 3103, which was subjected to deformation by either cold rolling or equal channel angular rolling (ECAR), was investigated. Samples of AA 3103 sheets were repeatedly deformed by ECAR up to six passes. In addition, AA 3103 was cold rolled to the same hardness level of the ECARed samples. Upon annealing, the cold rolled sample was recrystallized by the discontinuous recrystallization which gave rise to the formation of the cube texture and large grains bigger than 30 µm. In contrast, the ECARed sample was recrystallized by extended recovery which led to the formation of ultra-fine grains having a size smaller than 3.5 µm.
Properties of DLC Films Produced by Pulsed Laser Induced Arc Deposition
Authors: Jiang Na-na , Shao Tian Min , Chen Da Rong
Published: March 2009

Diamond like carbon (DLC) films were prepared on Si wafer, using laser induced arc deposition (Laser arc) technique. Results of Raman Spectra analysis showed that the as-deposit films were amorphous, having obvious sp3 structure. Meanwhile, surface topography and micro-tribological properties were investigated by using Atomic Force Microscope and Nano-Scratch Tester. Influences of arc voltage, substrate bias voltage, target materials and substrate pre-treatment methods upon the film structures and film properties were studied.
The Evaluation of the Elastic Property in Nano-Scaled Thin Compressive Film on Patterned Substrates
Authors: Moon M.W. , Kim T.Y. , Lee Kwang Real , Oh Kyu Hwan
Published: March 2009

The evaluation of elastic property for thin diamond-like carbon (DLC) films has been presented with buckle analysis of compressive stressed film on patterned substrate. When substrate has been patterned with adhesion release layer, the morphologies of buckle configuration on patterned layer has been controlled from straight sided (Euler) buckle to nonlinear telephone cord type buckle
with respect to the pattern width. By using the simple equation for Euler buckle, the elastic modulus has been easily calculated, shown well consistent with the results by nano-indentation test.
A New Low Alloy High Speed Power Hack Saw Blades
Authors: Gao Yuan , Xu Jin Yong , Liu Yan Ping , He Zhi Yong , Xu Zhong
Published: March 2009

Plasma surface alloying for low alloy high speed power hack saw blades was
introduced.The bulk material of the blade is made of low alloy steel, while the teeth of which possess a composition of high speed steel like as a result of surface modification by a plasma surface alloying process.It is a solid diffusion process eliminating method avoids the formation of coarse primary carbides which is a major problem encountered in the production of smelting high speed steel. As a result the carbides in the layer of high speed steel are fine and well-distributed.Therefore,it has not only well wear-resistance but also toughness. Besides, the blade also has the advantages of ease manufacturing and low cost.