bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of pH on the Morphology of Yttrium Oxide Hydroxide Nitrate Nanocrystal
Authors: Hong Zhang Lian , Guo Huang , Peng Li Xia , Wang Min Quan
Published: March 2009

Yttrium oxide hydroxide nitrate (Y4O(OH)9NO3), which was prepared by polyvinyl alcoholassisted hydrothermal method from the Y(NO3)3 and KOH starting solution, was characterized by XRD and FE-SEM. The results revealed that pH value of the starting solution is an important factor which determines the morphology and size of the products. The obtained products varied from lamina microprisms to circular nanorods when the pH value increased from 7.0 to 8.0. In the high pH value above 8.0, the size of nanorods decreased with increasing pH value. A primary mechanism was proposed to explain the evolution of morphology and size of Y4O(OH)9NO3 products prepared under various pH values.
Preparation of TiO2 Nanocrystalline Films by Electrophoretic Deposition and their Application in Dye-Sensitized Solar Cells
Authors: Wang Ning , Lin Hong , Li Jian Bao , Yang Xiao Zhan , Zhang Luo Zheng , Dou Yin
Published: March 2009

TiO2 nanocrystalline films were prepared by electrophoretic deposition (EPD) under a pulseperiodic electric field. The EPD behavior of TiO2 nanocrystalline suspension was investigated. The uniform 9.2-μm-thick TiO2 film was obtained by reasonably controlling the EPD condition. A dye-sensitized solar cell, with the EPD TiO2 film as the photoanode, obtained about 4.1% of photon-to-electron conversion efficiency (η). Its Jsc, Voc and fill factor (ff) are 11.6 mA/cm2, 0.65 V and 0.55, respectively. The effect of TiCl4 modification on the photovoltaic property of the solar cell was also discussed.
Microstructures and Properties of Al2O3/ZrO2 Composite Ceramics from In Situ Growth in the Melts Produced by Combustion Synthesis
Authors: Zhao Zhong Min , Zhang Long , Bai Hong Bai , Zheng Jian , Wu Jiang
Published: March 2009

By introducing ZrO2 (3Y) micron powder into the thermit, Al2O3/18%, 21%, 24%, 27% and
30%ZrO2 composite ceramics were obtained from in-situ growth in the melts produced by combustion
synthesis. As the volume fraction of ZrO2 is below 27%, the ceramics is comprised of lath-shaped and
rod-shaped α-Al2O3 matrix, within the rod-shaped grain the nano-micron fibers are oriented in essentially
the same direction. As volume fraction of ZrO2 is over 27%, the ceramics is mainly composed of
lamina-shaped grains with alternating α-Al2O3 and t-ZrO2 layers. The flexural strength and the fracture
toughness measured simultaneously the maximum values with increasing volume fraction of ZrO2 to 24%,
indicating that flexural strength and fracture toughness are simultaneously under the control of
rod-shaped grains in which ZrO2 nano-micron monocrystal fibers are embedded.
Preparation and Structural Characterization of SiO2-ZrO2 Aerogels
Authors: He Xiao Dong , Zhang He Xin , Li Yao , Hong Chang Qing , Zhao Jiu Peng
Published: March 2009

Low density SiO2-xZrO2 aerogels with x=35wt%, 65wt%, 75wt%, 90wt%, 95wt% were
prepared by CO2 supercritical drying technique with tetraethylorthosilicate (TEOS) and zirconyl nitrate
dihydrate (ZrO(NO3)2
.2H2O) by hydrolytic polycondensation under different chemical conditions. The
prepared aerogels are performed by X-ray Diffraction (XRD), Transmission electron microscopy (TEM),
Fourier transformed infrared spectroscopy (FT-IR) and BET surface areas to characterize and analyze the
morphology and pore structure of SiO2-ZrO2 aerogels. The results showed that the SiO2-ZrO2 areogels are
the typical of nano mesopores and the average pore size is about 50 nm. The specific surface areas varied
from 345.5 to 615.5 m2/g with (SBET)MAX = 615.5 m2/g with 20wt% Zirconia; Moreover a mass of Si-O-Zr
bands formed in the aerogels and the formation mechanism of Si-O-Zr bands are also discussed.
Synthesis and Structural Characterization of SiO2-Al2O3 Xerogels
Authors: He Fei , He Xiao Dong , Li Yao
Published: March 2009

Low-density xSiO2-(1-x)Al2O3 xerogels with x=0.9, 0.8, 0.7, 0.6 (mole fractions) were
prepared by sol-gel and non-supercritical drying. Silica alkogels, which were the framework of binary
composite materials, formed from tetraethyl orthosilicate (TEOS) by hydrolytic condensation with a
molar ratio of TEOS: H2O: alcohol: hydrochloric acid: ammonia =1: 4: 10: 7.5×10-4: 0.0375. Aluminum
hydroxide derived from Al(NO3)3·9H2O and NH4OH acting in the alcohol solution under the condition of
catalyst. After filtrating and washing, the precipitation was mixed into silica sols to form SiO2-Al2O3
mixed oxide gels with different silicon and aluminum molar ratio. The structural change and
crystallization of the binary xerogels were investigated after heat treatment at 600 for 2 h by the means
of X-ray diffraction. Nitrogen adsorption experiment was performed to estimate specific surface area,
porous volume and pore size distribution. The structural change of xerogels was observed by FT-IR
spectroscopy. The resulting mixed xerogels possess of mesoporous structure which is characteristic of
cylindrical pores, high specific surface area of 596-863 m2/g and a relatively narrow pore distribution of
2.8-30 nm. Al2O3 is introduced into the SiO2 phase and some of Al-O-Si bonds form.
Thermal Expansion Behavior of Solid Solution Y1.9R0.1Mo4O15 (R = Sm, Nd, Dy)
Authors: Wang H. , Peng J. , Cheng Y. , Wu M. , Hu Z. , Yu Z. , Chen D.
Published: March 2009

Several rare earth solid solutions of Y1.9R0.1Mo4O15 (R=Sm, Nd, Dy) with interesting thermal
expansion behavior were prepared and studied by X-ray and neutron diffraction. These solid solutions
crystallize in a monoclinic space group P21/c. The lattice parameters a, b and c of Y1.9R0.1Mo4O15 increase
with increasing of the ionic radius of substituted elementary. The high-temperature XRD data for
Y1.9Sm0.1Mo4O15 show that there is an unusual low thermal expansion behavior in the 25~100°C range
followed by a normal thermal expansion at higher temperature up to 600°C. Since no phase transition was
observed, the temperature dependence of Mo2-O14 bond distance seems to be responsible for the
anomalous thermal behavior.
Study on the Critical Time and Diffusion Coefficient in Grain-Boundary Segregation of Phosphorus
Authors: Liu Er Bao , Li Qing Fen , Chen Hong Bin
Published: March 2009

The critical times of phosphorus segregation in low alloy steel 12Cr1MoV at different solution
temperatures, 1050°C and 1300°C, are studied and the diffusion coefficient of complexes, Dc, and
diffusion coefficient of phosphorus, Di, are calculated. Results show that the calculated result with the
kinetic equations perfectly fits with the experimental observations. And that the higher the solution
temperature, the higher is the segregation level of phosphorus, and also the longer is the critical time. It
also shows that in the segregation process, the rate of phosphorus segregation at first is high due to a large
diffusivity of the complex, Dc. Then the segregation rate decreases due to decreasing complex
concentration gradient. In the de-segregation process, the level of phosphorus segregation decreases with
increasing holding time t. But the rate of phosphorus desegregation from grain boundaries to centre is
slower compared with that in segregation for the diffusion coefficient of phosphorus atoms, Di, is far
lower than that of the complexes, Dc.
Mechanical Properties of Filler Metal in Si3N4/Austenitic Stainless Steel/Si3N4 Joints as Measured by Nanoindentation and its Relationship to the Interfacial Strength
Authors: Cáceres Daniel , Polanco Raquel , Miranzo Pilar , Osendi María Isabel
Published: March 2009

Si3N4 specimens were joined in a high vacuum atmosphere under same experimental conditions using 50μm thick foils of three types of stainless steels (AISI 304, 316 and 321). The mechanical strength of these joints was evaluated by shear tests using a lap bond configuration and small but significant differences were found among them. Nanoindentation experiments were done on cross-sections of the bonded assemblies with a diamond Berkovich tip using an imposed penetration depth of 500 nm to reduce either surface effects or indentation size effect.
Preparation of BaSm2Ti4O12 Microwave Dielectric Ceramics via a Polyacrylamide Precursor
Authors: Huang Xian Li , Wang Fu Ping , Sun Qiu , Song Ying
Published: March 2009

A modified polyacrylamide precursor method is presented to synthesize BaSm2Ti4O12 microwave dielectric ceramics. Under an alkaline circumstance, all the cations together with the monomer and bridging agent were dispersed into a hydrous solution with the aid of chelating agent EDTA. This mixture was initiated at about 90°C, dried, calcined at 1000°C for 2hs and finally turned into well-crystallized and single-phased BaSm2Ti4O12 ceramic powder, which was modeled and sintered at 1250°C for 2hours into well-sintered ceramics. Differential thermal analysis, thermogravimetric analysis, X-ray powder diffraction and transmission electron microscope were used to characterize the process. Microwave dielectric properties measured by a resonating cavity method contain a dielectric constant (εr) about 77.0 and quality factor (Q×f) lager than 11000.
Microstructure and Dielectric Properties of LiTiNiO Thin Films
Authors: Dong Yan , Zhang Bo Ping , Zhang Ya Ru , Li Jing Feng
Published: March 2009

LiTiNiO thin films were deposited on Pt/Ti/SiO2/Si(100) substrates using a sol-gel spin-coat
method. The effects of annealing temperature and annealing time on microstructures and dielectric
properties of the thin films were investigated. SEM images showed the thin films had uniform and dense
microstructure and the grain size increased with increasing temperature and time. The LiTiNiO thin films
consisted of complex oxides which proportions were mainly dependent on the annealing condition. The
LiTiNiO thin film annealed at 600°C for 1h showed the highest dielectric constant and frequency stability,
while prolonging annealing time even at 600°C resulted in the decrease in the frequency stability of the
dielectric constants.
Effects of Ta5+ Substitution on Structure Transition and Microwave Dielectric Properties of Zn(Nb1-xTax)2O6 Ceramics
Authors: Zhang Ying Chun , Yang Xiu Hong , Yue Zhen Xing , Zhao Fei , Li Long Tu
Published: March 2009

The crystal structure, phase relation, microstructure and dielectric properties of microwave dielectric ceramics comprised of Zn(Nb1-xTax)2O6 were investigated systematically using XRD, SEM and a network analyzer in this study. XRD results show that the Zn(Nb1-xTax)2O6 ceramics have the orthorhombic for all x values. However, two kinds of solid solutions phase regions based on columbite structure and ZnTa2O6 structure were observed. SEM results show that the growth of grains is restrained with increase of Ta content in Zn(Nb1-xTax)2O6 ceramics. The dielectric properties exhibited a significant dependence on the crystal structure and compositions of the ceramics. The dielectric constant (εr) of Zn(Nb1-xTax)2O6 ceramics increased with increasing Ta content. However, the quality factors (Q×f) of this system show a different trend, and decrease with increasing Ta content. At x=0.65, a zero temperature coefficient of resonant frequency ( τ f) can be realized in Zn(Nb1-xTax)2O6 ceramics system.
Effects of CeO2 Additive on Property of Ba0.6Sr0.4TiO3-MgO Ceramics for Phase Shifter
Authors: Wang Xiao Hong , Lu Wen Zhong , Fan Gui Fen , Zhou Dong Xiang
Published: March 2009

The effects of cerium oxide on the dielectric properties and tunable properties of barium strontium titanate/magnesia (40wt%Ba0.6Sr0.4TiO3-60wt%MgO) compound ferroelectric material for improving the properties of phase shifter were investigated. The mechanism was also presented and discussed. The XRD patterns analysis showed that with increasing quantities of cerium oxide x (wt%), the lattice constant of BST-MgO material first increased to x=0.4, then changed a little till x=1.2. Further additions of CeO2 decreased the lattice constant. The dielectric properties at 10 kHz and microwave frequency were studied. The addition of CeO2 influences the dielectric constant, loss tangent and tunability greatly. The permittivity decreased with increase of cerium oxide nearly linearly. The addition of CeO2 effectively decreased the loss in BSTM ceramic. Optimum doping amount of CeO2 reduced the high frequency loss tangents of BST-MgO compound which also ensured the moderate dielectric constant and tunability. When the doping amount of CeO2 is 1.2wt%, BST-MgO composite has the following properties: εr = 92.64, tanδ = 0.00449 (at 2.6166 GHz) and tunability = 9.67% (at 2kV/mm), it is suitable for ferroelectric phase shifter.
Temperature Compensated (1-x)(Na0.5La0.5)TiO3+xCeO2 Microwave Dielectric Ceramics Incorporated with Copper Oxide
Authors: Hu M.Z. , Gu Hao Shuang , Qian J. , Xiong G. , Zhao Jun
Published: March 2009

The microstructures and microwave dielectric properties of temperature compensated composite
ceramics (1-x)(Na0.5La0.5)TiO3+xCeO2 doped with 1wt%CuO were investigated. Dense and mixed
phase samples were produced in the range of 0.1 ≤ x ≤ 0.9. As x value increases the Qf increases nonlinearly
while the dielectric constant decreases almost linearly. The compensated τf value is obtained in
0.1(Na0.5La0.5)TiO3 + 0.9CeO2 + 1wt%CuO ceramic with the Qf and εr being 8240GHz and 32.0
respectively.
Effect of ZnO-V2O5 Co-Doping on Phase Stability and Microwave Dielectric Properties of ZnTiO3 Ceramics
Authors: Yan Jing , Yue Zhen Xing , Wang Jin , Zhao Fei , Gui Zhi Lun , Li Long Tu
Published: March 2009

Zinc titanate ceramics having excellent dielectric properties and low sintering temperature are
promising materials for RF/microwave multilayer devices. In this paper, the ZnO-V2O5 addition was
added to promote the sintering process in order to obtain low-temperature sintered ceramics with high
quality factors. The sintering addition could also restrain ZnTiO3 phase from decomposition. Using this
method, low-temperature sintered zinc titanate ceramics with excellent microwave dielectric properties
of εr~ 25.3, Q×f~15200GHz, and τf ~ -16 ppm/oC were obtained at sintering temperature of 800oC. The
low-fired mechanism, microstructure, phase formation and microwave dielectric properties of ceramics
were investigated by XRD, SEM, EDS and network analysis techniques, respectively.
Research on Sintering Dynamics and Microwave Dielectric Properties of Bi and Mn Doped Lead-Based Ceramics
Authors: Zhao Jun , Gong Shu Ping , Xiong G. , Yu X.H.
Published: March 2009

The sintering dynamics, microstructures and microwave dielectric properties of Bi2O3 and
MnO2 co-doped [(Pb,Ca) La](Fe,Nb)O3 (PCLFN) ceramics were investigated. Bi2O3 and MnO2
dopants effectively enhanced bulk densities and reduced sintering temperatures by about 100~140°C.
Sintering procedure had significant effect on grain size and porosities of ceramics. Investigation of
microstructures revealed that the grain growth was controlled by either volume diffusion or
second-order interface mechanism in present ceramics. The potential microwave dielectric properties
of εr=91.1,Qf=4870GHz and τf=18.5ppm/°C could be obtained when the mass ratio of Bi2O3/MnO2
(k) was 1, the doping content w=1wt% and sintered at 1050°C for 4h.
Pb(Mg1/3Nb2/3)O3- Pb(Ni1/3Nb2/3)O3-PbTiO3 Crystals by Solid State Growth
Authors: Chen Ke Pi , Pan Jin Song , Zhang Xiao Wen
Published: March 2009

A small piece of <110> orientated relaxor-based ferroelectric Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals was embedded in Pb(Mg1/3Nb2/3)O3-Pb(Ni1/3Nb2/3)O3-PbTiO3 (PMN-PNN-PT) polycrystalline matrix to form the fully dense disk by spark plasma sintering (SPS) technique. Specimens were subsequently annealed to promote the boundary migration of the template single-crystal through a process termed as solid-state single crystal growth. It was found that the addition of excess 5 wt% PbO can promote the crystal growth, and the 2D morphology with V-shaped single crystals of PMN-PNN-PT were also observed. The possible growth mechanism was discussed.
Fabrication and Electrical Conductivity of a YSZ-NiCr Cermet
Authors: Shao Gang Qin , Li Jia , Li Yong , Duan Xing Long , Shi Xiao Liang , Zhang Wei Feng
Published: March 2009

YSZ-NiCr powder was synthesized by gel-reduction process at 850°C for 2 h. YSZ-NiCr cermet was fabricated by hot-press sintering at 1350°C for 1 h. The powder has a mean particle size of 42 nm and the sintered specimen has a fine and homogeneous microstructure with a mean crystalline size of 0.2 &m. The conductivity has a tendency to decrease with increasing temperature. This behavior can be accounted for that there are two conduction paths through the cermet, an electronic path through the Ni/Cr metal phase and an ionic path through the ZrO2-Y2O3 phase. The objective of this work is to give a possible improvement in the cermet anode of SOFC.
Dielectric Properties and Phase Transition of [110]-Oriented 0.68PMN-0.32PT Single Crystals Induced by Temperature and DC Electric Field
Authors: Li Zhen Rong , Qian Jun Jie , Zhang Guo Qiang , Xi Zeng Zhe , Xu Zhuo , Yao Xi
Published: March 2009

The dielectric response of [110]-oriented 0.68PMN-0.32PT single crystal under dc electric
field has been investigated. The characteristics of phase transition under temperature and dc electric field
are provided. When electric field is above 2.3kV/cm, abnormal phase transition is induced by temperature
and electric field, which corresponds to the phase transition from rhombohedral to orthorhombic
ferroelectric phase. With increasing dc electric field, the stable temperature region of orthorhombic phase
is expanded. The electric field-temperature (E-T) phase diagram of [110]-oriented 0.68PMN-0.32PT
single crystals is presented. The polarization rotation in [110]-oriented single crystal is discussed.
Structure and Ionic Conductivity of Ln2Zr2O7-Type Rare Earth Zirconates
Authors: Zhang Rui , Xu Qiang , Pan Wei , Wan Chun Lei , Qi Long Hao , Miao He Zhuo
Published: March 2009

Three rare earth zirconates (Sm2Zr2O7, Gd2Zr2O7 and Er2Zr2O7) were prepared by solid state
reaction. The crystal structure and ionic conductivity of these zirconates were characterized by X-ray
diffraction (XRD) and complex impedance spectroscopy. The results show that Sm2Zr2O7 exhibits
single-phase pyrochlore structure and Er2Zr2O7 exhibits single-phase fluorite structure, while Gd2Zr2O7
has pyrochlore and fluorite structure. Among three zirconates, the ionic conductivity of Sm2Zr2O7 is
highest, while that of Er2Zr2O7 is lowest.
Near-Infrared Luminescence and Energy Transfer Characteristics of Dy3+-Tm3+ Co-Doped Selenide Glasses
Authors: Yang Zhi Yong , Luo Lan , Chen Wei
Published: March 2009

Near-infrared emission properties of Dy3+-Tm3+ co-doped Ge-Ga-Sb-Se glasses were
investigated. Possible energy transfer routes and the regime of donor decay were discussed. Tm3+ is found
to be an efficient sensitizer on the Dy3+:1.34μm luminescence. Probable energy transfer schemes include
Tm3+:3H4 → Dy3+: 6F5/2 and Tm3+:3H5 → Dy3+:6F11/2·
6H9/2. The donor (Tm3+) excitation is transferred to
an acceptor (Dy3+) by direct interaction or migrates among donors by diffusion-limited regime until it
comes into the vicinity of an energy acceptor where direct interaction and transfer occur.
Effects of Glass Frits on the Properties of Luminescent Ceramics
Authors: Yan Jun Ping , Tang Zi Long , Luo Shao Hua , Zhang Zhong Tai
Published: March 2009

Sr4Al14O25: Eu2+, Dy3+ luminescent ceramics with high brightness and long afterglow were
prepared using glass frits as binders by sintering at lower temperature and air atmosphere. The effects of
glass frits on the properties of luminescent ceramics were discussed. The analytical results indicate that
the surface structure and adhesion with phosphor are influenced by glass frits and sintering temperature.
When sintered at 850°C, the samples with frit1 or frit2 obtained good surface morphology and good
adhesion. The sample with frit2 sintered at 850°C yielded the better surface morphology and good
adhesion. The sample with frit1 sintering at 850°C possessed the better luminescent properties.
Preparation and Acetone Sensitive Characteristics of Pure and Cu2+-Doped LaFeO3 Semiconductor Thin Films
Authors: Zhang Zhou , Ji Hui Ming , Gu Yan Fei , Chen Xiao Dong , Yu Dao Yin
Published: March 2009

Pure and Cu2+-doped LaFeO3 thin films were prepared on Al2O3 substrate by polymer complex
method using La(NO3)3⋅6H2O, FeCl3⋅6H2O and Cu(NO3)2⋅3H2O as raw materials, citric acid (CA) as chelating
agent and ethylene glycol (EG) as cross-linking agent. As-growth thin films were well-crystallized
and the grain size was about 40nm after being annealed at 650°C. The sensitivities of pure and Cu2+-
doped LaFeO3 thin films to 80 ppm acetone gas measured at 350°C were 315 and 30, respectively. Partial
substitution of Fe3+ in LaFeO3 with Cu2+ could widen testing temperature of the materials.
Dielectric Properties of LTCC System of Al2O3 and Borosilicate Glass
Authors: Liu Yang , Wang Yan , Ma Ju Sheng
Published: March 2009

In this paper, three types of Al2O3 powders with different sizes (1.6μm, 0.7μm, and 0.3μm)
were used in a LTCC system of Al2O3 and borosilicate glass (BSG). Al2O3 and BSG are selected on
account of their coefficient of thermal expansion (CTE) similar to silicon, which can reduce thermal
stress. It was found that the dielectric constant, ε, of substrates drops with the decrease of Al2O3 powder
size. ε increases with the increase of Al2O3 content for the sample with 1.6 μm Al2O3 powder, but
decreases with the increase of Al2O3 content for the samples with 0.7 μm and 0.3 μm Al2O3 powders.
SEM observations revealed that more pores with low permittivity appeared for the samples with smaller
Al2O3 powders, resulting in the drop of dielectric constant of the sample finally.
The Effect of Different Doping Methods of Sintering Aids on the Barium Titanate Based X7R Ceramics
Authors: Ma C. , Wang X.H. , Chen R.Z. , Li Long Tu , Gui Zhi Lun
Published: March 2009

The barium titanate based X7R ceramics, which are doped with rare earth oxide, Nb2O5, Co3O4
and ZnO-B2O3, could be sintered at a rather low temperature to satisfy the X7R requirements with good
permittivity and dielectric loss. In this paper, different doping methods of sintering aids have been used to
prepare X7R BaTiO3 ceramics. Samples were sintered at a low temperature and the relationship of doping
methods and sintering properties has been concluded.
Thermoelectric Properties of Bismuth Telluride Based Materials Prepared by Powder Metallurgy Processing
Authors: Ren Wei , Liu Xue Quan , Wang Xiao Lin , Jiang Hong Yi
Published: March 2009

Polycrystalline samples of Bi2Te3 based alloys were prepared by powder metallurgy processing
including a melting-grinding and a sintering procedure of compacted pellets. Two sintering procedures as
hot-pressing and spark plasma sintering (SPS) were employed. The thermoelectric properties and
mechanical strength were measured in all case. Thermoelectric properties for p-type (Bi0.25Sb0.75)2Te3 and
n-type Bi2(Te0.2Se0.8)3 changed with sintering temperature in both sintering methods. Mechanical strength
and relative density increase with sintering temperature in two sintering procedures. The results firmly
suggest that both sintering procedures are promising to obtain high performance thermoelectric materials.
Pulsed Micro-Electrochemical Machining Technology
Authors: Li Xiao Hai , Wang Zhen Long , Zhao W.S. , Hu Fu Qiang
Published: March 2009

This research work aims to explore the feasibility of applying electrochemical machining
(ECM) to micromachining. An experimental setup for micro-ECM has been developed. Lower
machining voltage, lower concentration of passivity electrolyte, high-frequency short-pulse power
supply and micro tool electrode rotating at high speed have been synthetically adopted to localize the
dissolution area in micro-ECM, so the machining gap can be kept at about 10 μm and the better
resolution of machined shape is achieved. A micro-hole with 45μm diameter is drilled on the stainless
steel foil with 100μm thickness. A new approach of fabricating microstructure by micro-ECM
milling with a simple micro electrode is proposed, and the micro beam with width of about 50μm
which has high precision is fabricated by micro-EC milling on the stainless steel foil (1Cr18Ni9Ti)
with 300μm thickness. A mathematics model has been established, which can be used to simulate the
process of shaping workpieces in the process of micro-ECM.
Amplification Ratio and Stiffness of Bridge-Type Flexure Hinge
Authors: Zhu Bao Guo , Ma Hong Wen , Yao S.M.
Published: March 2009

Bridge-type flexure hinge is a classical flexure amplification mechanism. The amplification ratio and stiffness are the key parameters in an amplification mechanism. Elastic mechanics was used to analyze the input and output stiffness of bridge-type amplification mechanism in relation to the translational and rotational stiffness of the flexure pivots. The result showed that the stiffness model can explain well the outer characteristic of bridge-type flexure hinge.
Elastic-Plastic Constitutive Equation Accounting for Microstructure
Authors: Takashima Shuji , Miyazaki Noriyuki , Ikeda Toru , Nakagaki Michihiko
Published: March 2009

In this study, we focus on the modeling of solid structures that include microstructures
observed in particle-dispersed composites. The finite element modeling can be used to clarify how the
macroscopic behaviors of solid structures are influenced by the microstructures. In such a case, if the
whole structure including the microstructures is modeled by the finite elements, an enormous number
of finite elements and enormous amount of computational time are required. To overcome such
difficulties, we propose a new method for modeling microstructures. In this method, an explicit form
of the stress-strain relation covering both elastic and elastic-plastic regions is derived from the
equivalent inclusion method proposed by Eshelby that provides mathematical solutions for stress and
strain at an arbitrary point inside and outside the inclusion. The derived elastic-plastic constitutive
equation takes account of the microstructures, so that the effect of microstructures on the macroscopic
behaviors can be obtained from the conventional finite element method by using such a constitutive
equation without modeling microstructures in the finite element analysis. The effectiveness of the
proposed constitutive equation is verified for a simple problem by comparing the results of the
one-element finite element analyses using the proposed constitutive equation with those of the
detailed finite element analyses using multi-element finite element modeling.
The Effect of Macroscopic Stress State on Transformation Rate in TRIP-Assisted Steels
Authors: Shan Ti Kun , Zhang Wei Gang , Lin Zhong Qin , Li Shu Hui
Published: March 2009

The dependence of the transformation rate on the multiaxial stress state corresponding to
different loading paths is investigated. On the basis of the single shear, uniaxial tension, plane strain
and equibiaxial stretching tests, the influence of stress state on stability of retained austenite is
analyzed and an equation of transformation kinetics is developed. In sheet metal forming, the material
undergoes complicated deformation, the prediction of the volume fraction of retained austenite
during forming process is essential to estimate the contribution of the TRIP effect to improving
formability. To this aim, the volume fraction of retained austenite in the part’s different regions has
been calculated using finite element method. The calculated results were compared with the
experimental data measured in deep drawing experiments.
Phase-Field Simulation of Surface Morphology Evolution during Epitaxial Growth of SiGe/Si System
Authors: Takaki Tomohiro , Tomita Yoshihiro
Published: March 2009

We have developed a phase-field model which can simulate the growth process of
self-assembled SiGe/Si islands during deposition. The novel feature of this model is that it can
reproduce the morphological transitions of islands, i.e., from single-faceted pyramid to multifaceted
dome and from dome to barn, by taking a high anisotropy and a sixteen-fold anisotropy of surface
energy into account. Two-dimensional simulations have been performed on a large computational
model. As a result, island nucleation on the surface of a wetting layer, island morphological change
and Ostwald ripening due to an interaction between two neighbor islands were well reproduced. The
bimodal distribution of island size, which is a very important phenomenon in self-assembled quantum
dots, could also be generated. Furthermore, it has been clarified that the bimodal distributions are
largely affected by island morphological change from pyramid to dome. Furthermore, in order to
discuss the mechanism of island growth, a simulation of single-island growth has been conducted and
the variations of island size and energies have been estimated in detail. As a result, it is concluded that
the island morphological transitions occur so as to reduce the elastic strain energy.
Study on the Microstructure and Mechanical Properties of PET and PET/PTT Blends
Authors: Ge Qiang , Ding Xu Jia , Wu Gang , Liang Song , Wu Si Zhu
Published: March 2009

In this study, the thermal analysis FTIR Micro-Spectroscopy method was used to observe
the energy changes of the functional groups of Poly(ethylene terephthalate) (PET) during
manufacturing progress. The conformational apparent enthalpy H in the melting process has been
calculated by the van’t Hoff equation at the constant pressure and then plotted with temperature. The
structure and properties of PET/PTT (Polytrimethylene Terephthalate) blends with different blending
ratio had also been studied by using DSC and DMA analysis.
Viscoplastic Constitutive Equation of High-Density Polyethylene
Authors: Sanomura Yukio , Mizuno Mamoru
Published: March 2009

A viscoplastic constitutive equation based on the kinematic hardening creep theory of
Malinin-Khadjinsky and the nonlinear kinematic hardening rule of Armstrong-Frederick is
formulated to describe the inelastic behavior of high-density polyethylene under various loading. The
gentle progress of back stress by the introduction of loading surface in the viscoplastic strain space
and smaller material constant under unloading can be expressed. Material constants are identified by
various stress-strain curves under compression at constant strain rate and creep curves under
compression at constant stress. The viscoplastic model can describe stress-strain curve under
compression with change in strain rate and shear stress-strain curve including unloading. The model
can qualitatively describe stress-strain curves under compression with changed strain rate including
unloading, but it is quantitatively insufficient.
Finite Element Analysis of V-Bending of Polypropylene Using Hydrostatic-Pressure Dependent Plastic Constitutive Equation
Authors: Hayakawa Kunio , Sanomura Yukio , Mizuno Mamoru , Kasuga Yukio , Nakamura Tamotsu
Published: March 2009

Finite element analysis of V-bending process of polypropylene was performed using
hydrostatic-dependent elastic-plastic constitutive equations proposed by the present authors.
Kinematic and isotropic hardening rule was employed for the plastic constitutive equations. The
kinematic hardening rule was more suitable for the expression of the stress reversal in uniaxial stress
- strain relation than the isotropic hardening. For the result of the finite element analysis of V-bending,
the kinematic hardening rule was able to predict the experimental behavior of springback more
properly than the isotropic hardening. Moreover, the effects of hydrostatic pressure-dependence were
revealed by examining the calculated distribution of bending plastic strain, bending stress and the
width of the bent specimen.
Shape Recovery and Secondary-Shape Forming in Polyurethane-Shape Memory Polymer
Authors: Tobushi Hisaaki , Ejiri Y. , Hayashi Shunichi , Miwa Norio
Published: March 2009

The influence of the strain-holding conditions on shape recovery and secondary-shape
forming was investigated. The results obtained are summarized as follows. (1) If strain is held at
holding temperature Th = Tg+20K in a short time, irrecoverable strain starts to appear at the holding
time th= 0.5h and strain is not recovered at all at th=8h. In the case of Th = Tg+10K, irrecoverable strain
appears in a short holding time if holding strain is large and the rate of secondary-shape forming S is
42% at th=8h. (2) If strain of 50% is held at Th = Tg+10K in a long time, strain becomes not to be
recovered and S is 93% at th =12h. In the case of Th = Tg, the increasing rate of S increases if th is
longer than 40h. If Th is lower than Tg-10K for th= 72h, strain is recovered perfectly by heating and
secondary-shape forming does not appear.
Prediction of Pressure and Density Dependent Failure in Sand-Like Granular Materials under General Stress Conditions
Authors: Huang Wen Xiong , Bauer Erich , Sloan Scott William
Published: March 2009

This paper presents a theoretical study of failure modes in sand-like granular materials
under general triaxial stress conditions based on a hypoplastic model and a bifurcation analysis. The
well developed constitutive model contains the void ratio as a state variable which allows the
pressure and density dependent behaviour of the granular materials to be described with a single set
of state-independent constitutive parameters. Based on this model a shear bifurcation condition is
derived. Loading along various stress paths that can be achieved with a true triaxial test apparatus
are simulated numerically. Either localized failure or uniform diffuse failure in granular samples
may occur, which is determined based on whether the shear bifurcation condition is met. Effects of
confining pressure and initial density are discussed.
Analysis of Elasto-Plastic Stresses and Structural Reliability of a Multilayer Pressure Vessel
Authors: Yu Shao Rong , Yin Yi Hui
Published: March 2009

In this paper, the formulas of elasto-plastic deformation and stresses of a multilayer
pressure vessel were deduced in consideration of the linear hardening elasto-plasticity of the
material, and the relations between plastic zone and interior pressure and between equivalent stress
and interior pressure were obtained for a monolayer vessel. Then, treating the strength problem of a
pressure vessel with a fuzzy or random one and based on the principle of the information entropy
theory that the information of a variable does not change with its expressed type, the fuzzy variables
in the problem were transformed into random ones or the random variables into fuzzy ones. At last,
the strength reliability degree of the pressure vessel was solved out by use of the random reliability
method and the fuzzy one, respectively. The relative error between the fuzzy and random reliability
degrees is 4.08% and the fuzzy reliability degree is closer to the determined one than the random
one.
Stress Analysis of Cold Die Compaction with Rotating Tools for Aluminum Powder
Authors: Kim Y.H. , Ma Xiang , Baek H.C. , Lim Chang Hwy
Published: March 2009

In this paper, a modified slab analysis has been used to determine the pressure
distribution in the cylindrical compaction of aluminum powder under rotating die compaction. The
analytical results are discussed to explain the pressure distribution and the interaction of the various
parameters. To predict the density distribution in a powder compact under an applied pressure with
torsion, the pressure function is coupled with some form of a pressure density relationship. High
relative density can be realized in powder compacts by the rotating die compaction in contrast to the
conventional compaction. A numerical analysis, using the DEFORM3D simulation software, is also
carried out on the compaction under the rotating punch.
Basic and Optimum Column Over-Design Factor Avoiding Story Mechanism for Frame Structures
Authors: Zhao Yan Gang , Pu Wu Chuan , Li Hong Nan , Ono Tetsuro
Published: March 2009

Ductile frame structures are generally designed with column over-design factors (COF)
to assure plastic hinges occurring in all beams and avoid unpreferable failure modes. In order to
avoid story mechanisms of frame structure constructed with elastic-plastic materials, target COF
has been investigated where the relative occurrence probability of most likely story mechanism is
limited within a specific tolerance. In the present paper, the concept of basic and optimum column
over-design factor for avoiding story mechanism are proposed and the value of them for multi-span
multi-story ductile frames are presented based on a comprehensive investigation on the occurrence
order of story mechanisms. The basic COF is defined as the critical value that the preferable failure
mode and unpreferable failure mode are with the same failure probability, and it is the low limit
assuring the entire beam-hinging pattern prior to story mechanisms. For a structure designed with a
COF less than basic COF, the plastic hinges are easier to occur in partial stories to form story
mechanism. The optimum COF is the most effective and economy COF to enhance the safety of
structure, and it is resulted from the shift of priority of plastic hinges in different stories. The
relationships between the basic and optimum COF with calculation parameters are also analyzed in
this paper.
Crystal Plasticity Analysis of Dislocation Accumulation in ULSI Cells with Consideration of Temperature Dependence of the Lattice Friction Stress for Silicon
Authors: Sato Michihiro , Ohashi Tetsuya , Maruizumi Takuya , Kitagawa Isao
Published: March 2009

Representative length scale of ULSI (Ultra Large Scale Integration) cells is going to be at
a nano-meter order, and the atomic level defects, such as uneven oxide films or dislocation
accumulation are becoming more and more important. Among these defects, dislocation
accumulation is known to be caused by thermo-plastic deformation in silicon during the processes
of device fabrication. In this study, we analyse such thermal stress, plastic slip deformation and
accumulation of dislocations in STI (Shallow Trench Isolation) type ULSI devices when the
temperature drops from the initial at 1000 °C to room temperature. For the analysis, we use a
crystal plasticity analysis code CLP, assuming that lattice friction stress for the movement of
dislocations is proportional to the hardness of silicon, which is known to have strong dependency
on temperature. The results show that dislocations are generated between the temperature range
from 880 to 800 °C, and its maximum density is highly dependent on the lattice friction stress in
the temperature range above 800 °C. For example, the difference of 16 MPa in the lattice friction
stress at 1000 °C caused increase in dislocation density more than ten times. It is concluded that
control of lattice friction stress at high temperatures is one of the most promising way for the
suppression of dislocation accumulation.
3-D Finite Element Simulation of Pulsating T-Shape Hydroforming of Tubes
Authors: Loh-Mousavi M. , Mori Kenichiro , Hayashi K. , Maki Seijiro , Bakhshi M.
Published: March 2009

The effect of oscillation of internal pressure on the formability and shape accuracy of the
products in a pulsating hydroforming process of T-shaped parts was examined by finite element
simulation. The local thinning was prevented by oscillating the internal pressure. The filling ratio of
the die cavity and the symmetrical degree of the filling was increased by the oscillation of pressure.
The calculated deforming shape and the wall thickness are in good agreement with the experimental
ones. It was found that pulsating hydroforming is useful in improving the formability and shape
accuracy in the T-shape hydroforming operation.
Dynamic Indentation and Penetration Properties of Aluminium Foams
Authors: Shen Jian Hu , Lu Guo Xing
Published: March 2009

Failure of aluminium foams due to dynamic indentation and penetration is very common in
their application such as light-weight structural sandwich panels, packing materials and energy
absorbing devices. This requires a sound understanding of deformation and energy absorption
mechanisms of the aluminium foams as well as the effect of impact velocity. In this study, a finite
element analysis using ABAQUS is conducted for the dynamic indentation/penetration process of
aluminium foams under a rigid flat-headed indenter. The indenter is pushed into the foam either at a
constant velocity or with an initial velocity. Two mechanisms exist: compression of the foam ahead of
the indenter and fracture along the indenter edge. Effect of impact velocity is noted on the size of a
localized deformation and the total energy absorbed.
Modeling of Fretting Wear Based on Cumulative Plastic Strain and Saturated Shear Stress
Authors: Liu Yong , Xu Jin Quan , Mutoh Yoshiharu
Published: March 2009

Fretting fatigue has grasped strong interest in last decades, some quantitative methods for
the evaluation of fretting fatigue were developed. However, only very few studies have been
reported on fretting wear, especially on its mechanical model and evaluation method. In this study,
cumulative plastic strain is analyzed by FEM. To obtain accurate plastic strain, the shape change
due to the plastic deformation has been taken into account. It is found that the cumulative plastic
strain will be saturated after several hundred cycles at the initial fretting stage. Considering that
fretting wear is very small during this early stage, as it can be observed from the fretting test, the
wear at the contact interface before the saturation of cumulative plastic strain can be neglected.
Since the saturated cumulative plastic deformation represents the stable deformation of the contact
interface, it is proposed that the fretting wear can be characterized by the saturated cumulative
plastic strain and accumulative shear stress. With this method, the wear profile of the specimen is
predicted. By comparing FEM results with the experimental results of fretting wear, the proposed
wear formulation is validated.
Interfacial Cracks of Antiplane Sliding Mode between Usual Elastic Materials and Quasicrystals
Authors: Shi Wei Chen , Li Huan Huan , Gao Qing Hai
Published: March 2009

The present study deals with the problem of interfacial cracks of antiplane sliding mode
between a usual elastic material and a one-dimensional hexagonal quasicrystal. Based on the physical
facts that balance of the phason stress field is foreign to the real force in or out of quasicrystal in
physical space, and the quasicrystal is bonded to a usual elastic material without both phason
displacement and stress fields, the problem is described by analytic functions and attributed to find
solutions of the Riemann-Hilbert problem. It is found that the stress intensity factor is not related to
phason strain field, and the phason stress field does not exist. The discontinuity of phonon
displacement field across crack is related to the phason displacement field because of the coupling of
phonon and phason strain fields. Although there is not the phason displacement on the bonded portion
of interface, it exists on the crack’s surface. The energy release rate obtained from interfacial crack’s
propagating is different from that of an interfacial crack between two different pure elastic materials.
Effect of Plastic Working on Pulsating Fatigue Strength of Notched Specimen
Authors: Hattori Nobusuke , Nishida Shinichi , Iswanto Priyo Tri
Published: March 2009

In order to study the effect of plastic working on fatigue strength of notched specimen,
pulsating fatigue tests had been performed on notched deformed stainless steel specimens including
on notched non-deformed specimens in order to evaluate the influence of mean stress on fatigue
strength. The test results showed that the fatigue limits of plastic worked specimens are higher than
that of non-worked one. This difference value would be caused by residual stress, work hardening and
fiber texture due to plastic working. When degree of plastic deformation equal zero ("t=0), the fatigue
limit ratio (σw /σB) of SUS430 is the higher than that of SUS304. On the other hand, the fatigue limit
of worked specimen for SUS304 increases as the plastic deformation value increases to 0.5 mm and
then it does not significantly increase from 0.5 mm to 1 mm. It is necessary to investigate an optimal
deformation value.
Formability of Al6061 Extruded Tube in Warm Hydroforming
Authors: Lee Young Seon , Lee Jung Hwan , Lee M.Y. , Moon Young Hoon , Ishikawa T.
Published: March 2009

Formability of tube in elevated temperature is essential data to design the warm
hydroforming process parameters, such as tube diameter, forming temperature and die geometries.
Since the quantitative data of forming limit can be used to predict the failure on forming process,
formability data available on the FE analysis is one of the very important information for the optimum
design. In this study, the effect of heat treatment conditions and deformation temperature on the
formability was investigated for the warm hydroforming of Al6061 tube. Full annealing and
T6-treatment are applied for the heat treatment of Al6061 tubes. To evaluate the hydroformability,
uni-axial tensile test and bulge test were performed at temperature ranges between room temperature
and 300oC. The measured flow stresses were used as input parameters for the simulation of warm
hydroforming process. The damage value and strain variation during hydroforming are analysed by
FEM. A forming limit based on the ductile fracture criteria has been proposed by combining the
results of experimental and FE analysis for the estimation of formability and optimization of warm
hydroforming process.
Texture Evolution and Grain Refinement in AA1050 Aluminum Alloy Sheets Asymmetrically Rolled with Varied Shear Directions
Authors: Lee J.K. , Lee Dong Nyung
Published: March 2009

Asymmetric rolling is a novel technique for giving rise to an intense plastic shear strain
through the sheet thickness. The shear strain also develops shear deformation textures close to the
{001}<110> and <111>//ND orientations, among which the latter is the most wanted component for
the deep drawability, and give rise to the grain refinement. Previously we analyzed various rolling
variables influencing the texture development and grain refinement in aluminum sheets obtained by
asymmetric rolling with different roll-radius ratios at the same rotation rate and varied reduction per
pass. In this study, AA1050 Al alloy sheets were asymmetrically rolled with a two-high mill of which
two rolls had the same diameter, but rotated at different rotation rates, with emphasis on effects of
combinations of shear directions in several passes. Textures and microstructures of the rolled sheets
were investigated by x-ray diffraction and electron backscattered diffraction analyses.
Mechanics of a Special Asymmetric Rolling of Thin Strip
Authors: Jiang Zheng Yi , Zhu Hong Tao , Wei Dong Bin , Tieu A. Kiet
Published: March 2009

Asymmetric rolling is used to produce thinner strip, which can reduce rolling force
significantly. When a thinner strip is rolled on a rolling mill, work roll edge may contact each other,
which affects the mechanics of this special asymmetric rolling and the crown of the rolled strip. In
this paper, the authors developed a numerical model to simulate this special rolling and obtained the
rolling force, intermediate force, roll edge contact force, the crown of the rolled strip and the edge
contact length. The effects of the initial thickness of strip and the friction variation at upper and
lower work rolls on the rolling force and crown of the rolled strip are also discussed.