bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation Aging of BaTiO3 Microwave Ceramic Capacitors for EMI Applications at High-Voltage
Authors: Xiong Zhao Xian , Su Z.G. , Qiu Hong
Published: March 2009

Degradation aging of BaTiO3 microwave ceramic capacitors for EMI applications at highvoltage,
AC 10kV, was focused in this paper. Electric performances of the ceramic capacitors were
systematically evaluated with thermal shock (5 cycles of –30 °C for 1 h and then 125°C for 1 h), damp heat
(100% RH at 40°C for 500 h), and, endurance at high temperature (DC 10 kV at 100°C for 500 h). High
reliability for the ceramic capacitor was obtained with optimal ceramic composition, sintering
temperature, epoxy resin, curing agent and additives, which was satisfied with practical microwave
technologies.
Synthesis and Characterization of (Gd, Y)-Doped Ceria Electrolytes for Solid Oxide Fuel Cell
Authors: Liu Zhi Hui , Guan Xiang Feng , Zhou He Ping
Published: March 2009

Ceria electrolytes co-doped with Gd3+ and Y3+ (Ce0.8Gd0.2-xYxO1.9) were synthesized by GNP.
The crystal structures, lattice parameters and crystallite sizes were determined by XRD. The morphology
of the powders was observed by TEM. Sintered at 1250oC for 4 h, all die-pressed ceria pellets achieved
densities higher than 95% of theoretical values. The ionic conductivities were measured using AC
impedance technique and Ce0.8Gd0.05Y0.15O1.9 showed a higher ionic conductivity than those of other
compositions at 500-750oC, indicating that it is an attractive electrolyte material for IT-SOFC.
High Performance Low Temperature Ceramic Fuel Cell with Zinc Doped Ceria-Carbonates Composite Electrolyte
Authors: Huang Jian Bing , Yang Li Zhai , Mao Zong Qiang
Published: March 2009

A kind of novel composite electrolyte, consisting of zinc doped ceria and carbonates, was
developed. The phase and morphology of the composite material were characterized. Ceramic fuel
cells based on this composite electrolyte were constructed with two techniques. The hydrogen-air fuel
cell fabricated with anode-supported technique showed relative low open circuit voltages (OCVs) and
high output performance, but the electrolyte-supported one exhibited relative high OCVs and low
output performance. During the fuel cell operation, water was observed at both anode and cathode
sides, indicating hybrid ions conduction lies in the composite electrolyte under fuel cell environment.
Dielectric Properties of Y3+-Doped Ba0.62Sr0.38TiO3 Ceramics
Authors: Li Yuan Liang , Qu Yuan Fang , Han Feng Long , Liu Chao , Li Xiao Yan
Published: March 2009

Microstructure and dielectric properties of Ba0.62Sr0.38TiO3 ceramics doped with x mol% (x=0.2~0.6) Y2O3 were investigated. SEM showed that Y3+ can accelerate growth of the grains at first, then turn to inhabit growth of the grains with further addition of Y3+ above 0.8mol%. The experimental results showed that the dielectric constants were improved with the additive amount of Y3+ increasing, if the amount of Y3+ increased continuously, the dielectric constants will drop, whereas the dielectric losses of the samples descended rapidly in the beginning, then went up obviously with further addition of Y3+ above 1.0mol%, the optimal dielectric constant and dielectric loss could reach 6700 and 0.0015 in the room temperature, respectively.
Modification of Optical Waveguide Material PMMA with Nano-Silicon by Sol-Gel Approach
Authors: Wang J. , Tang M. , Zhang F. , Xiong Zhao Xian , Zhou J.H.
Published: March 2009

Hybrid inorganic-organic materials based on alkoxysilyl-functionalized and poly (methyl methacrylate) were prepared by the in-situ sol-gel approach in the presence of tethaethoxysilance. Interaction between silica network and polymer was analyzed by FTIR, and its influence on phase behavior of hybrid was also investigated by SEM. Thermal analyses indicated that P(MMA-MSMA)-Si had higher value of Tg ,about 170°C, than that of pure PMMA. Meanwhile, the hybrid samples behave favorable optical transparency with small optical loss of around 2 dB.
Ga2O3 Films Grown on Sapphire by the Thermal Evaporation of GaN Powders
Authors: Kim Hyoun Woo , Myung Ju Hyun
Published: March 2009

We have prepared the gallium oxide (Ga2O3) films on sapphire substrates by a thermal evaporation of GaN powders. We have characterized the films by using the x-ray diffraction (XRD), scanning electron microscopy (SEM), and the photoluminescence (PL). SEM and XRD revealed that the deposits were Ga2O3 thin films with monoclinic structure. PL spectrum of Ga2O3 films under excitation at 325 nm showed a blue emission.
On the Multilayered Chip-Type PTC Elements Prepared by Roll-Forming Process
Authors: Liu Huan , Gong Shu Ping , Zhou Dong Xiang
Published: March 2009

We describe the fabrication of chip-type PTC elements (BaTiO3-based) by roll-forming process. Crack-free green tapes with good malleability are successfully obtained with the thickness typically in the range of 0.20~1.0mm. We also focus on reducing the room-temperature resistance of the chip-type PTC element without deteriorating its PTC effect, both by controlling the firing schedule and by introducing multilayer structure with electrode-bonding method. The typical size of the 5-layered chip-type PTC sample obtained is 8.0mm×5.0mm×1.95mm with R25=1.97- and Rmax/Rmin=4.8×105.
Optimization of the Effective Parameters on the Synthesis of the Mn-Zn Ferrite Powder with a High Saturation Magnetization Using Different Iranian Routs of Iron Oxide
Authors: Seyyed Ebrahimi S.A. , Sepehri Amin H. , Hormozan Y. , Tabibzadeh P.
Published: March 2009

Mn-Zn ferrites with chemical formula (Mn-Zn) Fe2O4 have widespread applications in the
electrical and electronics industries. These ferrites are synthesized generally by conventional method.
This method, which contains calcination of raw materials, is affected by several parameters such as
composition and purity of the raw materials and temperature, time and atmosphere of the process.
Optimization of these parameters is very important because these parameters affect the magnetic and
electrical properties of the material. In this work, the ratio of the different Iranian routs of the raw
materials for production of high Ms ferrite powder has been optimized and the effects of calcination
conditions have been investigated using XRD, DTA/TGA techniques. The magnetic properties have
also been measured.
High Temperature Thermoelectric Property of Sr-Filled Skutterudite SryCo4Sb12
Authors: Zhao Xue Ying , Shi Xun , Chen Li Dong , Bai Sheng Qiang , Zhang Wen Bing , Tang Xin Feng
Published: March 2009

Sr-filled skutterudite compounds SryCo4Sb12 (y=0-0.20) were synthesized by melting method.
XRD and EPMA results revealed that the obtained samples are single skutterudite phase with
homogeneous chemical composition. The lattice parameters increase linearly with increasing Sr content
in the range of y=0-0.20. The thermal conductivity, electrical conductivity and Seebeck coefficient were
measured in the temperature range of 300-850K. The measurement of Hall effect was performed by Van
de Pauw method at room temperature. The obtained Sr-filled skutterudite exhibits n-type conduction. The
absolute value of the Seebeck coefficient of SryCo4Sb12 decreases with the increase of Sr content. The
electrical conductivity increases with the increase of Sr content. The lattice thermal conductivity of
SryCo4Sb12 is significantly depressed as compared with unfilled CoSb3. The maximum dimensionless
thermoelectric figure of merit is 0.7 for Sr0.20Co4Sb12 at 850K. Further optimization of chemical
composition would improve the thermoelectric performance.
Structural and Optical Ceramics: Yesterday, Today, and Tomorrow
Authors: Wei George C.
Published: March 2009

Ceramics contributes to progression of civilization. Yet advancement of ceramic science and technology benefits from the improved infrastructure and productivity. This paper assesses the development of structural and optical ceramics in the last quarter century. For example, structural ceramics such as silicon carbide whisker reinforced alumina matrix and titanium carbide dispersed silicon carbide matrix composites have made possible high-speed, wear-resistant, specialty tools. Designing of the structural materials involved consideration of thermodynamic compatibility of phases during fabrication, and consideration of the initiation and propagation of fracture. Mechanisms of the observed toughening have been proposed on a scale ranging from continuum to microstructure to atomistics. Optical ceramics including translucent polycrystalline alumina have facilitated the construction of high-pressure sodium and ceramic metal halide lamps. The microstructure and properties such as transmittance and sodium resistance of polycrystalline alumina have improved. The starting powders improved in purity, particle size, and de-agglomeration. Sintering of alumina advanced through optimization of dopants and sintering atmosphere. Densification involves grain-boundary diffusion; retardation of grain growth is due to solute drag. The solid solubility of magnesia sintering aid in alumina is a function of grain size. During grain growth and sintering of magnesia-doped alumina, both the enriched dopant level at grain boundaries and the equilibrium dopant content in the lattice alter, resulting in boundary pinning and pore annihilation. Oxygen vacancies when in motion significantly influence the boundary transport, and when stationary are important to optical properties of the sintered alumina. Further development of improved and new functional ceramics involves consideration of energy and environmental renewability. Prior achievements and outstanding challenges will be discussed.
Preparation of (Ca+M) (M=Mg, Yb, Sr) Co-Doped α-SiAlON Powders by Combustion Synthesis
Authors: Liu G.H. , Chen Ke Xin , Zhou He Ping , Ren Ke Gang , Pereira C. , Ferreira José Maria F.
Published: March 2009

In this paper, α-SiAlON powders co-doped with (Ca+M) (M=Mg, Yb, Sr) were prepared by combustion synthesis. The effect of Ca incorporation on the phase composition and grain morphology of reaction products was discussed. The experimental results showed that Ca incorporation promoted the growth of rod-like α-SiAlON crystals in (Ca+Mg) and (Ca+Yb) systems. For (Ca+Sr) system, the addition of Ca assisted Sr into α-SiAlON crystal lattice and increased the relative content of α-SiAlON in reaction product.
Fabrication of (Ba,Sr)TiO3 Thin Films by Hydrothermal Crystallization of Sol-Gel Precursor
Authors: Ma Jing Yun , Miao Hong Yan , Tan Guo Qiang , Sun Zheng Qiu
Published: March 2009

Barium strontium titanate (BST) ferroelectric thin films have been successfully prepared on the single crystal silicon substrates using hydrothermal crystallization of sol-gel precursor, which combined the conventional sol-gel process and the hydrothermal method. The precursor film was deposited by the dip-coating method. The multiplayer BST gel films were hydrothermally treated in a Teflon vessel at low temperature of 160-180 °C for 1-3.5 h. The influences of the reaction conditions on the structure and crystallizing degree of BST thin films were discussed. We find that the temperature of as-dried gel films and post hydrothermal treatment are the critical parameters determining the quality of formation of BST thin films. Under optimized conditions, we can obtain well-developed perovskite BST films with smooth and pinhole-free surfaces. These results reveal that this technique is a promising low temperature process for the fabricating of thin films.
Preparation and Characterization of Ca0.8Sr0.2ZrO3 Powders Prepared by Soft Chemical Route
Authors: Lei Ji Xia , Liu Xiao Lin , Yan Tao , Chen Jian Feng
Published: March 2009

Precursors of calcium strontium zirconate (Ca0.8Sr0.2ZrO3) were synthesized by oxalate coprecipitation
method. TG-DTA was used to characterize the thermal decomposition behaviors of the precursors.
The XRD results revealed that the powders crystallized as cubic Ca0.8Sr0.2ZrO3 with increasing
heating temperature up to 1000°C. Calcium strontium zirconate ceramics were obtained under conventional
sintering conditions by using the as-prepared Ca0.8Sr0.2ZrO3 powders. The SEM micrographs of the
ceramics sintered at 1450oC exhibited narrow grain-size distribution with the average grain size around
0.7 4m. The dielectric properties showed that, dielectric constant of the Ca0.8Sr0.2ZrO3 was about 24.0 and
dielectric loss was 0.002 at the frequency of 1GHz and the room temperature.
Research of Grinding Concave Paraboloiding Piece by Spherical Grinding Wheel
Authors: Wang Hui Feng , Wang Guang Lin , Lu Ze Sheng
Published: March 2009

Aiming at the ultra-sophisticated combined working machine tool that was developed,
the motion style of the machine tool when abrasive machining a sort of inward-curving-parabolic
shape optical aspherical surface device is analysed, according to the equation of the machined part’s
surface, the relative movement locus between the cutter and the machined part can be established
while using a spherical grinding wheel as grinding cutter. The caliber of the paraboloid that to be
processed is analysed, and the grinding wheel's installation angle is chosen, as well as the cutting
speed of the cutting spot is analysed, the abrasive model in ideal condition is analysed, the basis is
based for error compensating.
The Characteristics of Frictional Behaviour in CMP Using an Integrated Monitoring System
Authors: Lee Hyun Seop , Park Boum Young , Park Sung Min , Kim Hyoung Jae , Jeong Hae Do
Published: March 2009

Chemical mechanical polishing (CMP) has become the preferred technology to achieve global planarization of wafer surfaces. Especially in oxide CMP, mechanical factors have a greater effect on the removal rate than chemical factors. So, the effects of mechanical parameters in CMP can be expressed as friction force and heat caused by friction. The friction force can be evaluated by a CMP friction force monitoring system and process temperature can be obtained by an infrared rays (IR) sensor. Furthermore, friction energy can be calculated from the friction force monitoring system. In this paper, research on the correlation between frictional and thermal characteristics of SiO2 slurry and CMP results was conducted. This data, which was obtained by using integrated monitoring system for CMP, will lead to the efficient prediction of CMP results.
Computerized Tomography and C-Scan for Measuring Drilling-Induced Delamination in Composite Material Using Twist Drill and Core Drill
Authors: Hocheng H. , Tsao Chung Chen
Published: March 2009

Delamination is one of the most concern defects in drilling of composite material. Delamination depends on the factors such as feed rate, tool geometry and wear. The mechanics of drilling composite materials has been examined along with the quality of the hole and the effect of tool design parameters. The capacity of computerized tomography (CT) showing sample cross-section in a nondestructive way made it successful in measuring the drilling-induced delamination. In the experiment, the correlation between thrust force and the measured delamination extent in use of twist drill and core drill is illustrated and compared with the known ultrasonic C-scan. It is compared with the ultrasonic technique and is demonstrated a feasible and an effective tool for the evaluation of drilling-induced delamination.
Experimental Research of On-Line Fabrication of Tool-Electrode Base on Electrochemical Micromachining
Authors: Guo Zhong Ning , Zeng F.Z. , Han G.H. , Huang Zhi Gang
Published: March 2009

A new method for on-line fabrication of micro tool-electrodes is presented in this paper.
The method is base on the machining mechanism of electrochemical micromachining. By exchanging
the polarities of the tool-electrodes and workpiece repeatedly, micro tool-electrode appropriate for
electrochemical micromachining can be obtained through mutual machining. Because the processes
are carried out on-line, the position error and clamp error caused by twice-clamp of tool-electrodes
can be avoided, and the machining precision can be improved greatly. This method will be very
important to electrochemical generating micromachining. Experiments are carried out, and a
tool-electrode with the pinpoint of 20μm can be machined stably.
Replication for Microstructure Using Soft Mold
Authors: Park S.J. , Chung S.G. , Jeong Hae Do
Published: March 2009

In this paper, a new replication technique for 1D, 2D, and 3D microstructure was
introduced, in which a master pattern was made of photo-curable epoxy using
microstereolithography technology, an etching process, and a dicing process. Next, it was transferred
onto an epoxy. Barrier ribs were selected as the 1D microstructure, and a rectangular pattern was
selected as the 2D microstructure. A helical gear was selected as one of the real 3D microstructures
for this study, and these were replicated from pure epoxy. In addition, the life span of the soft mold
for using the micro replication process was evaluated.
An Experimental Study on Milling Al2O3 Ceramics with Abrasive Waterjet
Authors: Feng Yan Xia , Huang Chuan Zhen , Wang Jun , Hou Rong Guo , Lu X.Y.
Published: March 2009

The machining performance of Al2O3 ceramics is studied by abrasive waterjet (AWJ) milling experiment. The machined surface characteristics and the effect of process parameters on machined surface quality are analyzed. The results showed that the nozzle traverse speed and traverse feed have a strong effect on the machined surface quality. The effect of process parameters on material volume removal rate and the milling depth is also researched. The results indicated that the material volume removal rate and the milling depth would be increased at the milling conditions of higher water pressure and bigger standoff distance. However, the milling depth will decrease at the milling conditions of higher traverse speed and higher traverse feed, and the material volume removal rate has a complex variation.
Experimental Study on Precision Hole Machining with Squeeze Film Damping Technology
Authors: Yu Tian Biao , Gong Ya Dong , Liu J. , Xu F. , Wang Wan Shan
Published: March 2009

A grinding wheel spindle with squeeze film damper—SFD is designed based on squeeze
film damping theory and relevant grinding experiments have been performed. Experimental results
indicate that the rationality of design for SFD can make the vibration of the grinding wheel spindle is
reduced by 25%. The precision of hole machining is improved by 20%. At the same time, work
efficiency of the grinder can be raised about 15%. So it has very important research value and wide
application prospect in the field of machining.
Temperature and Strain Rate Effects on Mechanical Behavior of a PMMA
Authors: Suo Tao , Li Yu Long , Liu Yuan Yong
Published: March 2009

In this paper, the mechanical behavior of a PMMA used as the windshield of aircraft was
tested. The experiments were finished under two quasi-static strain rates and a high strain rate with
the testing temperature from 299K to 373K. The results show that the mechanical property of this
PMMA depends heavily on the testing temperature. The Young’s modulus and flow stress were
found to decrease with increasing temperature at low strain rate. At the strain rate of 10-1 1/s, strain
softening was observed under all experiment temperatures. At high strain rate, with the temperature
increasing, the flow stress decreases remarkably while the failure strain increases, and the strain
soften was also observed at the temperature above 333K. Comparing the experiments results at
same temperature, it was found the flow stress increases with the rising strain rate. The predictions
of the mechanical behavior using the ZWT theoretical model have a good agreement with
experimental results in the strain range of 8%.
Quasi-Static and Dynamic Axial Crushing of Various Polygonal Tubes
Authors: Yamashita Minoru , Hattori Toshio , Nishimura Naoya , Tange Y.
Published: March 2009

Various polygonal tubes were compressed in the axial direction under quasi-static and
dynamic loading conditions. The effect of the polygonal shape and the wall thickness on the crush
behavior is investigated, in which the cyclic buckling takes place. The numbers of polygonal edges
were 3, 4, 5, 6 and 7 in the experiment. A circular tube was also tested for comparison. The tubes
were machined from aluminum alloy A5056 bar. Crush strength is estimated as an index of the
energy absorption capacity of the tube. It increases with increasing the number of polygonal edges
of the tube, although it almost saturates when the number of polygonal edges is more than 6. For the
wider variety of polygonal tubes than that in the experiment, numerical simulation is performed
using the dynamic explicit finite element code DYNA3D. The computed crush behavior well agrees
with the corresponding experimental one, however, the difference in collapse mode arises due to the
slight imperfections in experiment. The deformation pattern becomes more irregular for the
thinner-walled tube. Further, it is presumed that the large hardening exponent in the plastic property
of the material could prevent the buckling switching from the symmetric mode to asymmetric one
in the crushing of circular tube.
Effect of Pitting Corrosion on Ultimate Strength of Web Plates Subjected to Shear Loading
Authors: Nakai Tatsuro , Matsushita Hisao , Yamamoto Norio
Published: March 2009

Pitting corrosion is a great concern when the integrity of ship's hull structures is considered.
Corrosion pits with a conical shape are typically observed on coated hold frames in way of cargo
holds of bulk carriers which exclusively carry coal and iron ore. Therefore, it is important to
investigate the effect of pitting corrosion on local strength of hold frames of bulk carriers. In the
present study, a series of 3-point bend tests with structural models which consist of web, shell and
face plates has been conducted. In these tests, a concentrated load has been vertically applied at the
center of simply supported models so that shear load would act on the web plate with artificial pits. In
this testing condition, load increased even after shear buckling occurred. When there is artificial
pitting, fracture of web plates occurs due to strain concentration at the pits. It has been revealed that
the empirical formula, which was developed based on non-linear FE-analyses, overestimates the
equivalent thickness for the shear ultimate strength obtained in the present experiment, because the
effect of web fracture is not taken into account in the analyses.
Effect of the Surface Defects on Hydroformability of Aluminum Alloys
Authors: Kim B.J. , Choi K.H. , Park K.S. , van Tyne Chester J. , Moon Young Hoon
Published: March 2009

Extruded aluminum alloys, which are highly versatile, have relatively modest prototyping
cost, good strength and corrosion resistance. Because there is no weld seam, the circumferential
mechanical properties may be uniform and advantageous for hydroforming. However, surface defects
such as die lines and pick-up can be generated during the extrusion especially due to imperfections on
the die surface. In this study, the extent of the crack propagation caused by die lines is evaluated
according to the deformed shape of the tube in hydroforming process. And when forming a extruded
aluminum tube, the deformed surface of the tube frequently becomes rougher with increasing plastic
strain. This is well known as orange peel phenomenon and it has a significantly effect not only on the
surface quality of a final product but also on the forming limit. To evaluate the effects of the orange
peel on the hydroformability, the inter-stage polishing has been performed. Through the several tests
including hydroforming test, the effect of surface defects on the hydroformabilities are well defined.
Flow and Temperature Analysis of Molten Pool in Twin-Roll Strip Casting Process
Authors: Zhang Xiao Ming , Jiang Zheng Yi , Yang L.M. , Liu Xianghua , Wang Guo Dong
Published: March 2009

In twin-roll strip casting process, metal flow and temperature distribution in the molten
pool directly affect the stability of the process and the quality of products. In this paper, a 3D coupling
temperature-flow finite element simulation during twin-roll strip casting has been carried out, and the
influences of the outlet angle and the submerged depth on the temperature and flow fields in the
molten pool were investigated for the twin-roll casting of stainless steel. An inverse method was used
to determine the boundary conditions between the roll and molten pool. Simulation results are
consistent with the experimental values. Numerical simulation is helpful to optimise the twin-roll
strip casting process and to improve the quality of products in practice.
Degradation Behaviors of β-TCP/PLGA Composites Prepared with Microwave Energy
Authors: Park Hong Chae , Jin Hyeong Ho , Hyun Yong Taek , Lee Won Ki , Yoon Seog Young
Published: March 2009

The β-tricalcium phosphate (β-TCP)/ poly(lactide-co-glycolide) (PLGA) composites for
biodegradable scaffolds in bone tissue engineering were synthesized by in situ polymerization with
microwave energy. The degradation behavior of β-TCP/PLGA composite was investigated by
soaking in simulated body fluid (SBF) for 4 weeks. The molecular weight of the β-TCP/PLGA
composites decreased with soaking time until week 2, whereas the loss rate of molecular weight
reduced after week 2. The incubation time was needed for the degradation of the β-TCP, indicating
that the β-TCP should be detached from the PLGA matrix and then degraded into SBF solution. The
studies of mass loss of the composites with the soaking time revealed that the degradation behavior of
PLGA would be processed with the transformation from the polymer to the oligomer followed by the
degradation. Morphological changes, whisker-like, due to transformation and degradation of polymer
in the composites were observed after week 2. On the basis of the results, it found that the
degradation behavior of β-TCP/PLGA composites was influenced by the β-TCP content in the
composite and the degradation rate of the composite could be controlled by the initial molecular
weight of PLGA in the composite.
Development of Rapid Cell Recovery System Using Temperature-Responsive Nanofiber Surfaces
Authors: Ko Young Gwang , Jeon Hyeon Ae , Yoon Kwan Han , Kim Young Chul , Ahn Chang Hyun , Kim Young Jin , Kwon Oh Hyeong
Published: March 2009

PHBV ultrafine fibers were fabricated by electrospinning process. Electrospun PHBV
fiber structures revealed randomly aligned fibers with average diameter of 400 nm. PIPAAm was
grafted on the surface of PHBV nanofibrous mat by electron beam irradiation. PIPAAm-grafted
PHBV mats were determined by ATR-FTIR and ESCA. Water contact angles were determined by a
sessile drop method at 20 and 37. To examine the tissue compatibility, human fibroblasts were
evenly seeded onto PIPAAm-grafted PHBV mat and cast film, ungrafted PHBV mat and film.
Attached and spread fibroblasts on nanofibrous mat were proliferated more rapidly than that of flat
film surface. Initial cell attachment on PIPAAm-grafted surfaces was higher than ungrafted
surfaces. The surface property changed to hydrophilic by PIPAAm graft, which increased initial cell
attachment. Detachment of single cells from PIPAAm-grafted PHBV matrixes was measured by
low temperature treatment after incubation at 37. Cultured cells were rapidly detached from
PIPAAm-grafted PHBV mat compared with film. With porous mats, the water molecules easily
reach to grafted PIPAAm from underneath and peripheral to the attached cells, resulting in rapid
hydration of grafted PIPAAm molecules and detachment of the cells.
Inclusion Complex Formation of Water- Soluble Drug, Captopril, and Peracetylated-β-Cyclodextrin in Supercritical CO2 for Controlled Release Applications
Authors: Ganapathy Hullathy Subban , Woo Min Hee , Gal Yeong Soon , Lim Kwon Taek
Published: March 2009

The inclusion complex of CO2-soluble peracetylated-β-cyclodextrin (PAc-β-
CD), heptakis(2,3,6-tri-O-acetyl)-β-cyclodextrin, and highly water-soluble drug captopril,
was prepared by a chemical solvent-free method using supercritical carbon dioxide. The
captopril-PAc-β-CD inclusion complex was further confirmed by DSC and XRD studies.
In- vitro release of captopril from an oily suspension confirmed that the dissolution rate of
captopril was much retarded from the inclusion complex as a result of the hydrophobic
properties of PAc-β-CD.
Evaluation of Hydroxyl Groups on Hydroxyapatite and Calcium Metaphosphate by Grafting TEOS and APTES
Authors: You Chang Kuk , Kim Sung Min , Ahn Myun Whan , Kim Seong Yong , Kim Suk Young
Published: March 2009

OH groups on hydroxyapatite (HA) and calcium metaphosphate (CMP) were evaluated
by grafting tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethyloxysilane (3-APTES) which
can bond covalently with OH group of ceramic biomaterials. The prepared HA and CMP disks were
soaked in pH 2 and 5 of acidic water and ethanol solution respectively, where pH change of each
solution was measured during soaking of samples. After grafting TEOS and 3-APTES on HA and
CMP disks, samples were ultrasonically cleaned in distilled water and soaked in pH 5 of ethanol
solution, and pH measurement was carried out in the same manner. The pH value of HA and CMP
in aqueous solution at pH 2 increased with time continuously, resulting from dissolution of HA and
CMP by acidic condition on surface. At pH 5 in aqueous solution, it was the same though the pH
increase was smaller. In case of ethanol at pH 5 with HA, though pH value went up slightly, the
curve became saturated with time, while there was no change in pH with CMP. After grafting
TEOS and 3-APTES, pH values were stabilized with few changes, indicating that there was no
direct chemical reaction between the acidic media and the surface of samples due to covalently
grafted TEOS and 3-APTES layer. In conclusion, it was confirmed that OH group on the surface of
HA was crystallographic and chemical one rather than physically adsorbed one by grafting TEOS or
3-APTES and it will serve an effective binding site for calcium and phosphate ions, or minerals.
Effect of Solvent on the Characteristics of Electrospun Regenerated Silk Fibroin Nanofibers
Authors: Jeong Lim , Lee Kuen Yong , Park Won Ho
Published: March 2009

Nonwoven nanofiber matrices were prepared by electrospinning a solution of silk fibroin
(SF) dissolved either in formic acid or in 1,1,1,3,3,3-hexafluoro-2-isopropyl alcohol (HFIP). The
mean diameter of the electrospun nanofibers prepared from SF dissolved in formic acid was 80 nm
with a unimodal size distribution, which was smaller than those prepared from HFIP (380 nm). SF
nanofibers were then treated with an aqueous methanol solution, and structural changes due to
solvent-induced crystallization of SF were investigated using IR and 13C solid-state CP/MAS NMR
spectroscopy. SF nanofibers prepared from formic acid were found to have a higher proportion of
β-sheet conformations than those prepared from HFIP. Methanol treatment provided a fast and
effective means to alter the secondary structure of both types of SF nanofibers from a random coil
form to a β-sheet form. As demonstrated in the present study, this approach to controlling the
dimensions and secondary structure of proteins using various solvents may be useful for the design
and tailoring of materials for biomedical applications, especially for tissue engineering applications.
An Improvement in Shock Absorbing Behavior of Polyurethane Foam with a Negative Poisson Effect
Authors: Park K.O. , Choi Jae Bong , Park Jong Chul , Park D.J. , Kim Jeong Koo
Published: March 2009

Polyurethane foam was fabricated by ‘two-component method’ for changing cell
structures. Compression force applied immediately to the polyurethane foam just after complete
foam formation at the top of the mold for generation cell structure of negative Poisson effect. That
is what we called pressure-controlled method. The polyurethane foam, produced by pressurecontrol
method (CT), has significant higher resilience (52.3%) and similar level of shock absorption
(47.5%) compared with control polyurethane foam (resilience is 21.5%, shock absorption is 54%).
The PU foam with negative Poisson’s ratio showed excellent resilience with shock absorbance. The
pressure-control method divided into two parts (CT0, CT1). The CT1 method is to apply
compression force to the foam with time-delayed after foam formation. The PU foam produced by
CT1 showed lower stress relaxation time, stress relaxation ratio, and maximum stress than CT0.
Hence, CT1 foam is superior to other polyurethane foam as shock absorbing materials, such as
shoes for diabetic patients.
Mechanical Characterization of Metal Sheets by Means of Double Indentation
Authors: Quadrini Fabrizio , Santo Loredana , Squeo Erica Anna
Published: March 2009

An easy and innovative technique for metal sheet characterization is described. A double
indentation is performed on sheets by means of two co-axial small diameter flat indenters made of
WC. A very small indentation is left on the sheet, so as to consider this technique a non destructive
one, particularly suitable for on-line application. The proposed method was tested on sheets of
aluminum alloy (6082 T6) with several thicknesses (nominally 0.6, 0.8, 1 and 1.5 mm). Double
indentations were performed changing indenter diameter (1 and 2 mm) and testing rate (from 0.05
to 1 mm/min). In order to make a comparison with indentation tests, flat specimens were cut from
the same sheets and standard tensile tests were performed. A very good correlation was found
between indentation and tensile test results, showing the effectiveness of the proposed method. A
suitable data normalization is necessary to correctly compare indentation and tensile data. The best
results were obtained using the smaller diameter indenter. The testing rate seems to be not relevant
in the experimented range, suggesting that a fast procedure can be defined on purpose for on-line
application.
Acoustic and Optical Monitoring of High-Power CO2  Laser Cutting
Authors: De Keuster Johan , Duflou Joost R. , Kruth Jean Pierre
Published: March 2009

In this paper, the development of a monitoring system for high-power CO2 laser cutting
of thick steel plates (>15 mm) is reported. The aim of this system is to increase the robustness and
autonomy of the laser cutting process of thick plates, which is still characterized by more narrow
process windows compared to cutting of thin sheets. The applicability for monitoring purposes of
two types of sensors is investigated: the acoustic microphone and the photodiode. For both types,
correlation between the sensor output and the cut quality is investigated. Both contour cutting and
piercing are covered in the study. The full penetration of the piercing can be monitored by both
sensors. Furthermore quantitative relations between cut quality parameters and photodiode signal
parameters could be determined: the mean level of the photodiode signal correlates well with the
drag of the striations and dross formation, whereas the standard deviation proves to correlate well
with the occurrence of burning defects and the cut edge roughness.
Effect of Water Jet Orifice Geometry on Jet Behaviour and Cutting Capability
Authors: Annoni Massimiliano , Monno Michele
Published: March 2009

The internal geometry of water jet orifices is important to determine water velocity and
structure of the jet: the geometrical features of orifices, such as diameter, rounding of the entrance
edge, taper angle of internal walls and so on, play an important role under the fluid-dynamic point of
view and, consequently, on water velocity and jet behaviour in air, which are responsible for the
available value of specific power on the workpiece. The aim of this study is to experimentally
evidence possible differences among performances of orifices coming from different manufacturers
in order to point out the effects of orifices geometrical features on water velocity and cutting
capability in case of abrasive water jet cutting of Aluminium.
Laser-Assisted Bending
Authors: Mäntyjärvi Kari , Keskitalo Markku , Karjalainen Jussi A. , Leiviskä Anu , Heikkala Jouko , Mäkikangas Jarmo
Published: March 2009

When sheets of high-strength (HS) and ultra-high-strength (UHS) steels are bent by a
press brake the process suffers from large bending forces, considerable springback, and eventual
cracks. Additionally, some unpredictable effects, such as lost contact to the punch, caused by strain
hardening may occur producing a bend with erroneous radii. The strain hardening of the bending
line may make further processes, such as forming or welding, more complex. One solution to these
problems is to anneal the bending line with a laser in advance. Of course, it is also possible to utilise
other types of heat sources, but the laser can offer the most precisely controlled heat treatment. The
proper process parameters depend on the material, and it has been noticed that inadequate process
parameters may harden the material instead of annealing. In this work some experiments on bending
sheet metal samples of HS or UHS steel with previously laser-annealed bending lines have been
carried out and the outcome analysed. The results show that the annealing produces better bending
results compared to the conventional procedure. This includes lower springback, less hardening in
the bending line and more precise geometry of the bend. It can be even suggested that proper
annealing with strain hardening in bending will produce the original material structure. Obviously,
more theoretical and experimental work is required to optimise the process parameters including the
laser power and speed for each pair of material strength and thickness.
Straight Hemming of Aluminum Sheet Panels Using the Electromagnetic Forming Technology: First Approach
Authors: Jimbert P. , Perez I. , Eguia I. , Daehn Glenn S.
Published: March 2009

Hemming is the last or one of the latest stage operations for the stamped parts. For this
reason it has a critical importance on the performance and perceived quality of assembled vehicles.
It is used to attach two sheet metal parts together or to improve appearance creating a smooth edge
rather than a razor edge with burrs.
However, designing the hemmed union is not always easy and is deeply influenced by the
mechanical properties of the material of the bended part. Main problems for the automotive industry
arise when bending aluminum alloys.
Aluminum sheet is more difficult to hem due to its susceptibility to strain localization during the
hemming process. This phenomenon produces cracking on the hemmed edge [1].
In order to avoid this problem and due to the limitations of conventional flanging and hemming
technologies, the flange radii must be increased and a rope hem used (instead of the flat hem used
with steels) when working with aluminum alloys. These changes on the design of the hem union
give as a result a lower quality final product [2].
Dies and tools used for the hemming process are designed based on experience and on lengthy and
costly die tryouts.
Continuing with the development of new applications for the Electromagnetic Forming (EMF)
technology, LABEIN-Tecnalia and Professor Glenn Daehn’s group from The Ohio State University
carried out some first straight flat hemming experiments using the AA 6016 T4 aluminum alloy.
The results obtained from these first trials are presented in this paper giving a first sight of the
possibilities, advantages and disadvantages of using the Electromagnetic Forming technology for
the hemming of aluminum sheet panels.
Using a non-clouped FEM simulation method, the experimental results are compared to the ones
obtained with the simulations.
The future working line in developing this new application for the Electromagnetic Forming
technology will be based on the results obtained by this study.
Integration of Electromagnetic Calibration into the Deep Drawing Process of an Industrial Demonstrator Part
Authors: Psyk Verena , Beerwald C. , Henselek A. , Homberg Werner , Brosius Alexander , Kleiner Matthias
Published: March 2009

In recent years a steadily growing interest in applying lightweight construction concepts
could be observed. This development is accompanied by an increasing demand for innovative
forming strategies suitable for extending the forming limits of the typical lightweight materials.
Deep drawing combined with an integrated electromagnetic calibration step is an example of such a
technology. The feasibility and potential of this process combination is analyzed on the basis of a
demonstrator part from the automotive industry. Thereby, aspects related to the practicability of the
electromagnetic forming process itself are regarded as well as points related to the deep drawn
preform. The concept of a 3D-coil insert, integrated into a deep drawing punch in order to realize
the calibration in the deep drawing process, is introduced and based on the experimental results,
conclusions regarding the applicability of the process combination are drawn.
Improvement of Filling of Die Corners in Box-Shaped Tube Hydroforming by Control of Wrinkling
Authors: Loh-Mousavi M. , Mori Kenichiro , Hayashi K. , Bakhshi M.
Published: March 2009

The filling of the die corner in hydroforming of a tube with a box die was improved by
controlling wrinkling under oscillation of internal pressure. In this process, a small wrinkle occurs
near the die corner in the former stage, and then the wrinkle is eliminated in the latter stage because
the flat bulge appears in the former stage due to the oscillation of internal pressure. A hydroforming
process of steel tubes with a box die was performed in both three dimensional finite element
simulation and experiment. The filling of the die corner for the mean linear pressure was not sufficient
due to large wrinkles appearing in the former stage, whereas bursting occurs for the peak linear
pressure due to round bulging. On the other hand, the uniformity of wall thickness of the formed tube
was improved by the pulsating pressure.
Three Dimensional Finite Element Analysis of Transverse Free Vibration of Self-Pierce Riveting Beam
Authors: He Xiao Cong , Pearson Ian , Young Ken W.
Published: March 2009

Self-pierce riveting (SPR) is nowadays widely used in the car manufacturing industry
where aluminium alloys are used for body construction. For the design of mechanical structures,
formed by the joining of component parts, a knowledge of the vibration characteristics of different
joint types (adhesive bonding, spot welding, SPR etc) is essential. The free transverse vibration
characteristics of single lap-jointed encastre SPR beams are investigated theoretically in this paper
using the three dimensional finite element method (FEM). Numerical examples are provided to
show the influence on the natural frequencies, natural frequency ratios and mode shapes of these
beams caused by variations in the material properties (E and υ) of the sheet material. It is shown
that the transverse natural frequencies of single lap jointed encastre SPR beams increases
significantly as the Young’s Modulus of the sheets increases, but only slight changes are
encountered for variations of Poisson’s Ratio. It is found that an exponential curve gives an
acceptable fit to the relationship between natural frequency and Young’s Modulus. As expected,
odd modes shapes were found to be symmetrical about the mid-length position and even modes
were anti-symmetrical.
Effect of Chemical Etching on Adhesively Bonded Aluminum AA6082
Authors: Borsellino C. , Di Bella G. , Ruisi V.F.
Published: March 2009

The efforts of new automotive industry are mainly directed towards the substitution of
aluminum for steel in the body structure because the aluminum structures are lighter than traditional
steel ones and meet the requirements, in terms of both vehicle design and manufacture. However,
this substitution is not so automatic, but it is important to study the material properties and the
structure design, focusing the attention on the methods of joining.
Welding, typical technique to joint steel parts, is particularly difficult when applied on aluminum
ones and then, in many cases, the adhesive bonding is preferred.
To optimise the joint performances it is necessary to pre-treat the metal surface, not only to remove
contaminants, but also to provide the intimate contact needed for the adhesive to successfully bond
with the adherent surface.
The mere cleaning of aluminum surfaces is not suitable for their bonding due to the oxide layer that
naturally occurs on exposure to air so we need to apply a more effective treatment (mechanical or
chemical etching) to increase the adhesion capability of the substrates.
In this work different adhesive joint configurations (single lap) between aluminum substrates are
studied. Two different resins are employed to evaluate the influence of the adhesive on the joint
performances. Moreover the aluminum sheets are treated with a chemical etching with two different
procedures.
Tool Path Design in Friction Stir Spot Welding of AA6082-T6 Aluminum Alloys
Authors: Buffa Gianluca , Fratini Livan , Piacentini Mario
Published: March 2009

In the paper, a variation of the Friction Stir Spot Welding (FSSW) process has been
considered. In particular, a particular tool path is given after the sinking phase nearby the initial
penetration site. The process mechanics was highlighted and the joint strength was considered at the
varying of the most relevant process parameters. Furthermore macro and micro analyses were
developed in order to highlight the process mechanics and the local material microstructure
evolution. The investigated technology appears a promising joining technique in order to develop
effective spot joints.
Management of Complexity in Automotive Companies in the West Midlands UK
Authors: Villegas Miguel , Shirvani Bez
Published: March 2009

Quality Management Systems (QMS) of volume production car makers tend to be large.
Complexity levels in such structures are difficult to manage. From the design release to the
production stage, a manufacturer has to control roughly 9000 parts (including fixings) for a large
size car. A large number of subsystems, together with their coupled interactions increase a system’s
complexity. Results of the application of a model to manage complexity in some automotive
companies in the West Midlands (UK) suggest that complexity reduction leads to quality
improvements.
Assessment of Best Scheduling Practice in Continuous Casting and Hot Rolling of Stainless Steel Strip by System Dynamics Simulation
Authors: Storck Joakim , Lindberg Bengt
Published: March 2009

A rapid flow of materials with little intermediate buffering between steel mill and hot
strip mill has many benefits. One is energy savings due to raised charging temperature in the reheat
furnaces of the hot strip mill. Another is that tied capital is freed up, thereby improving mill
economy. Still, it is not unusual that average lead-time is in the order of days, or even weeks.
The aim of the present work was to show how lead-times from casting to rolling could be
improved by changes in the scheduling function. A System Dynamics model of a stainless steel
strip production facility with continuous caster and hot rolling mill was created. The model was
used to study the dynamics of the system in response to changes in parameters that defined the
scheduling configuration.
More frequent schedule updating generally resulted in less work in process (WIP) and shorter
lead times from casting to rolling, with resulting higher charging temperatures. The amount of
oscillation in the system was also reduced. More frequent work roll changes were required when
scheduling frequency increased, resulting in an increased fraction of setup time in relation to total
processing time. Therefore, a development towards increased scheduling frequency may have to be
complemented by efforts to reduce changeover times.
The conclusion was that dynamic scheduling routines with frequent schedule updating result in
better overall performance of the system due to lower WIP and better heat utilization. Dynamic
scheduling routines with frequent updates make the system respond better to changes in the system
and give better overall performance. The result is lower WIP, increased energy efficiency and less
oscillation in the system.