bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrational Properties of Sodium Substituted β-Tricalcium Phosphate
Authors: Quillard Sophie , Obadia Laetitia , Deniard Philippe , Bujoli Bruno , Bouler Jean Michel
Published: March 2009

The infrared and Raman spectra of Na substituted β-TCP are presented for various levels of substitution. The influence of Na content on main vibrational modes appears significant and among them the ν1 symmetric stretching band is very sensitive to PO4 3- tetrahedrons environment. Thus, this mode was particularly investigated and has been decomposed using Lorentzian shapes components. We assigned the calculated components to the different types of PO4 3- tetrahedrons present in the crystalline structure.
Nanozirconia Partially Coated MWNT: Nanostructural Characterization and Cytotoxicity and Lixivation Study
Authors: Garmendia Nere , Bilbao Leire , Muñoz Roberto , Goikoetxea L. , García Ainara , Bustero Izaskun , Olalde Beatriz , Garagorri Nerea , Obieta Isabel
Published: March 2009

Carbon nanotubes could avoid the crack propagation and enhance the toughness of the
ceramic material used for prostheses applications. So nanozirconia partially coated carbon
nanotubes have been obtained via hydrothermal synthesis of zirconia nanoparticles in presence of
multiwall carbon nanotubes. The as covered nanotubes should have a better wettability in the
ceramic matrix and improve the dispersion of the CNTs in the nanocomposite, which results in a
new ceramic biomaterial with a longer lifetime and better reliability. The obtained product has been
structurally characterized by several techniques such as FTIR, XRD, SEM, AFM, EELS, XPS and
TGA. The citotoxicity of the sintered product was studied by the change in the pH and ICP-AES in
in-vitro biocompatibility tests.
Biomimetic Hybrid Composites to Repair Osteochondral Lesions
Authors: Tampieri Anna , Sandri Monica , Landi Elena , Pressato Daniele
Published: March 2009

The present work describes the development of biomimetic materials for osteochondral
tissue substitution and repair, which can be the start for a revolution in the classical procedures of
orthopedic surgery. Performing biomineralization process, we succeeded to prove that biological
system store and process information at the molecular level. The substitute consist in three layers:
the lower layer, mimicking bone tissue, is formed by HA/Collagen (70/30)wt; the intermediate
layer, mimicking the tade-mark, is formed by HA/Collagen (40/60)wt; and the upper layer,
mimicking the cartilagineous layer, is formed by Collagen containing Hyaluronic Acid. In vivo tests
performed on small and large size animals should that: the bony portion well integrate and
gradually are reabsorbed in contact with femoral bone in rabbit. The osteochondral substitute
showed the ability to repair defect in osteochondral lesion opened in horses knee and differently
stimulate cells thanks to the different chemico-morphological-microstructural features of the
scaffold layer.
Microstructure Designing of Porous β-Tricalcium Phosphate for Control of Reactions in the Bone
Authors: Ioku Koji , Kamitakahara Masanobu , Kawachi Giichiro , Gonda Yoshinori , Okuda Takatoshi , Yonezawa Ikuho , Kurosawa Hisashi , Ikeda Tohru
Published: March 2009

Porous materials of β-tricalcium phosphate (β-Ca3(PO4)2; β-TCP) were prepared from porous hydroxyapatite (Ca10(PO4)6(OH)2; HA) with calcium deficient composition of Ca/P molar ratio of 1.50 synthesized by hydrothermal method. The porous β-TCP was composed of rod-shaped particles of about 10-20 μm in length. Rod-shaped particles were locked together to make micro-pores, and the size of micro-pores formed by tangling of rod-shaped particles was about 0.1-0.5 μm. The particle size and micro-pore size could be controlled by our unique method. It must be suitable for the bone graft material and as the scaffold of cultured bone.
Conversion of Octacalcium Phosphate into Hydroxyapatite and Bone Regeneration
Authors: Suzuki Osamu , Kamakura Shinji , Anada Takahisa
Published: March 2009

The present study was designed to investigate the mechanism of in vivo conversion from
synthetic octacalcium phosphate (OCP) into hydroxyapatite (HA) at ultrastructural level, where the
implanted OCP is enhancing bone regeneration in mouse calvarial bone defect. OCP granules were
implanted into the subperiosteal area of the calvaria of 7-week-old BALB/c mice for 3 weeks.
Transmission electron microscopy of undecalcified frontal sections, obtained from the acrylic
resin-embedded skull specimens showed that the bone crystals in newly formed bone directly bonded
to the OCP particles implanted. The morphological characteristic of original plate-like OCP particles
was remained unchanged even after the implantation, whereas a number of de novo nano-particles
were also directly formed onto the plate-like OCP particles. Some of OCP particles were linked with
other OCP particles through these nano-particles. The results suggest that the OCP-apatite conversion,
involving the enhanced bone regeneration, advances via topotaxial conversion without changing the
original OCP morphology, accompanied by solution-mediated de novo nano-apatite formation, in the
vicinity of the implanted OCP particles.
Chemical Detoxification of AflatoxinB1 in Rice by Several Solutions through Fluorescence Spectral Experiment
Authors: Chen Wen Li , Zhou Quan , Xing Da
Published: March 2009

AflatoxinB1 was extracted from rice contaminated artificially with Aspergillus flavus by
using methanol-water (50:50 v/v). As for experiment group, sodium chloride was added into the
extracted solution of AfB1, the excitation wavelength of 365 nm under the fluorescence mode, and
the emission spectrum peak at 440nm were observed. To study the detoxification of AflatoxinB1 in
several alkaline solutions, the solution of alkaline with difference concentration was added into the
solution of AfB1 respectively. The results showed that all of three alkaline solutions could decrease
the 440nm emission spectrum peak of solution of AfB1 in varying degrees, the effect to decrease
emission spectrum peak of AfB1 was very obvious in sodium hypochlorite (NaClO), and sodium
hydroxide (NaOH) took second place, whereas in ammonia (NH3·H2O), the effect was the weakest
among three alkaline solutions. Moreover, the effects were different in the same alkaline solutions
with different concentration, as hydrochloric acid (HCl) in low concentration was added to this
complex AfB1 alkaline solutions, detoxification efficacy of AfB1 were found to be obviously
increased. It was concluded that the detoxification of AflatoxinB1 may be affected by alkaline
solutions according to their concentration and be degraded greatly by acid addition.
Measurement of Progressive Addition Lenses
Authors: Wang Qin , Yu Jing Chi , Chen Hao
Published: March 2009

Methods on the measurement of progressive addition lenses (PALs) are summarized.
Principles and characteristics of several comparatively promising kinds of methods based on
Computer-aided Focimeters, optical sampling (Hartmann Testing, Ronchi Inspecting etc.) and
Moiré Deflection Technology (MDT) are described. Corresponding typical arrangements of the
measurement devices used in these methods are provided too. After being compared with each
other in their features, their respective advantages and application limitations are analyzed. Also,
the new development tendencies of these methods are discussed. Based on foregoing comparison
and analysis, key problems and difficulties on the measurement of progressive addition lenses are
put forward. In the end, the future of the inspection of progressive addition lenses is proposed.
Photoacoustic Imaging Application in Tumor Diagnosis and Treatment Monitoring
Authors: Xiang Liang Zhong , Zhou Fei Fan
Published: March 2009

Photoacoustic imaging (also called optoacoustic or thermoacoustic imaging) can image
vascularity clearly with simultaneous high contrast and high spatial resolution, and has the potential
to be an application for tumor diagnosis and treatment monitoring. In a unique photoacoustic
system, a single pulse laser beam was used as the light source for both cancer treatment and for
concurrently generating ultrasound signals for photoacoustic imaging. The photoacoustic system
was used to detect early tumor on the rat back, and the vascular structure around the tumor could be
imaged clearly with optimal contrast. This system was also used to monitoring damage of the
vascular structures before, during and after photodynamic therapy of tumor. This work
demonstrates that photoacoustic imaging can potentially be used to guide photodynamic therapy
and other phototherapies using vascular changes during treatment. Prospective application of
photoacoustic imaging is to characterize and monitor the accumulation of gold nanoshells in vivo to
guide nanoshell-based thermal tumor therapy.
FE Analysis and Position Accuracy Estimation of Machining System for Lens of Mobile Devices
Authors: Baek Seung Yub , Lee Eun Sang , Lee Jung Hyung , Shin Min Jung
Published: March 2009

In order to obtain competitiveness in the field of industrial manufacturing, a reduction in the development period for the batch machining of products is required. It is essential to analyze the stress distribution and deformations of machining system which is used for manufacturing the aspheric lens using FEM software ANSYS. Finite element simulations have been performed in order to study the influence of machining system which was developed in this study on structures. It is very important to understand the structural behavior of machining system. This research investigated the static analysis and dynamic analysis of machining system for aspheric lens to predict the damage due to loading.
Target Tracking in Micro Injection Molding
Authors: Yung Kai Leung , Liu Hang , Xu Yan , Hu Hong , Ko Sui Man , Kwan Matthew , Lau Kon Sau , Tam Kam Fai
Published: March 2009

The precision control of the injection process in micro injection molding demands precise
tracking of the moment that melt front passes through the nozzle so that accurate prediction of the
amount of melt being injected into the mould can be achieved. The tracking accuracy, to large
extent, depends on the processing of pressure signals followed by the identification of the critical
moment that melt front reaches the nozzle. A new adaptive Kalman filter was introduced in this
study to calculate and predict the amount of melt injected. The filter eliminated the delay error and
was more robust than other filters. The adaptive Kalman filter switches between two Qs for steadystate
and transient estimations, allowing resetting of the Kalman gain so that convergence is
speeded up in calculations. Experimental and simulation results prove the effectiveness of the
method proposed.
Residual Strain Measurement of Femtosecond Laser Microexploded Glass by Nanoindentation
Authors: Dong Shen , Wang Yan Shen , Yang Yan Qiang , Liang Ying Chun , Sun Tao , Wang Ying Hui , Zheng Zhi Ren
Published: March 2009

By focusing femtosecond laser pulses in the bulk of a quartz wafer, sub-surface
waveguides were microexploded. The material around the femtosecond laser induced
microexplosive zone was densified, which altered local refractive index. Changes in material
density can take corresponding variations in nanomechanical properties, which were proved by the
depth dependent modulus and hardness variations tested by nanoindentation in the area around the
microexplosive zone. Changes in refractive index were correlated with residual strains along radial
direction of the waveguide cross section. An equation of residual strain in such area that based on
nanoindentation data was set up, so as to discover density and refractive index variations in the
adjacent areas of femtosecond laser microexplosive zone indirectly.
The Current State and Development Trends of Deterministic Ultraprecision Optical Surfaces Machining Technology
Authors: Luo Song Bao , Yang Hui , Zhang Jian Ming , Pang Chang Tao
Published: March 2009

The deterministic ultraprecision machining achieves accuracy and repeatability not possible using conventional optical machining techniques, greatly enhances product quality, providing a quantum leap in throughput, productivity, yield, and cost effectiveness. The deterministic ultraprecision machining technology, involving various ultraprecision process from turning, flycutting, grinding and polishing to finishing, is usually referred to the following technologies such as single point diamond turning (SPDT), deterministic microgrinding (DMG), magneto-rheological finishing (MRF),computer controlled polishing (CCP), and computer controlled optical surfacing(CCOS),etc. This paper discusses mainly the current state and development trends of the deterministic ultraprecision machining technologies at home and abroad. In addition, the paper also elaborates on the technical features of the various deterministic machining technologies mentioned.
A Scanning White-Light Interferometric Profilometer for Smooth and Rough Surface
Authors: Dai Rong , Xie Tie Bang , Chang Su Ping
Published: March 2009

A profilometer for micro-surface topography measurement is presented. The instrument is based on the scanning white-light microscopic interferometry (SWLMI). A Linnik type interference microscope is used and the interferograms which present changes of surface profile are recorded by a CCD camera. A developed nano-positioning work stage with integrated optical grating displacement measuring system realizes the precise vertical scanning motion during profile measurement. By white-light phase shifting algorism of arbitrary steps, frames of interferograms are processed by computer to rebuild and evaluate the measured profile. Because of the specialty of SWLMI, the profilometer is suitable for both smooth and rough surface measuring. It also can be used for the measurement of curved surface, dimension of MEMS etc. The vertical resolution of the profilometer is 0.5nm, lateral resolution 0.5+m.
Structural Design of a Bench-Type Ultra-Precision Machine Tool for Micro-Structured Optical Components
Authors: Yang Yuan Hua , Chen Shi Jin , Sun Xi Zhi , Cheng Kai
Published: March 2009

Micro-structured optical components (MOCs) show great promise for offering an
exciting new degree of freedom and flexibility to optical designers and producers. At present, these
micro/miniature components are usually manufactured by large ultra-precision machine tools in
tightly controlled environment and the cost of machining is thus very high. In this study, a novel
machine with compact structure and flexibility was built, specially used for machining of the
MOCs. The key points of the design are given. Fresnel lens, as an example of MOCs, was machined
by this machine tool, and the result shows that the form accuracy of the machine tool is in the order
of sub-micrometer.
Block Copolymer Films Hierarchical Assembly in Confinement
Authors: Cao Yong Zhi , Dong Shen , Liang Ying Chun , Sun Tao , Yan Yong Da
Published: March 2009

Ultrathin block copolymer films are promising candidates for bottom-up nanotemplates
in hybrid organic-inorganic electronic, optical, and magnetic devices. Key to many future
applications is the long range ordering and precise placement of the phase-separated nanoscale
domains. In this paper, a combined top-down/bottom-up hierarchical approach is presented on how
to fabricate massive arrays of aligned nanoscale domains by means of the self-assembly of
asymmetric poly (styrene-block-ethylene/butylenes-block-styrene) (SEBS) tirblock copolymers in
confinement. The periodic arrays of the poly domains were orientated via the introduction of AFM
micromachining technique as a tool for locally controlling the self-assembly process of triblock
copolymers by the topography of the silicon nitride substrate. Using the controlled movement of 2-
dimensional precision stage and the micro pressure force between the tip and the surface by
computer control system, an artificial topographic pattern on the substrate can be fabricated
precisely. Coupled with solvent annealing technique to direct the assembly of block copolymer, this
method provides new routes for fabricating ordered nanostructure. This graphoepitaxial
methodology can be exploited in hybrid hard/soft condensed matter systems for a variety of
applications. Moreover, Pairing top-down and bottom-up techniques is a promising, and perhaps
necessary, bridge between the parallel self-assembly of molecules and the structural control of
current technology.
Development of a Dynamic Model for Ultra-Precision Raster Milling
Authors: Kong Ling Bao , Cheung Chi Fai , To Suet , Lee Wing Bun
Published: March 2009

Optical freeform surface requires submicrometer form accuracy and nanometer surface
finish. Ultra-precision raster milling is an emerging technology in the fabrication of those surfaces
in which the dynamics factors are vital to achieve the surface quality. This paper presents a
theoretical dynamics model for ultra-precision raster milling. The cutting force is derived in the
depth of cut (DOC) planes in the feed and raster directions. Hence, a 3D cutting force model is
established. The cutting force induced deflection between tool and workpiece is determined which
can be employed to analyze the influence of the deflection on the surface generation in raster
milling. The dynamic model is useful for modeling of surface generation and further control of
vibration between the tool and the workpiece.
Fabrication of Large-Area Imprint Mold with High-Aspect-Ratio Nanotip Arrays of Sub-Micron Diameter
Authors: Ting Chia Jen , Tsai Hung Yin , Chou Chang Pin
Published: March 2009

Many research works have been focusing on nanoimprint technology due to the recent potential mass production for the nanostructure applications. For optical or display application, a nanoimprint mold of large area becomes one of the thorniest techniques since it takes much time to fabricate the whole mold with nanostructure and it may make the beginning nanostructures inconsistent with the final ones. In order to fabricate the nanostructure mold of large area in a short time, the plasma process forming nanostructures on silicon substrate and the electroforming process are explored in the current study. Well-aligned nanotip arrays of 4 inch silicon were fabricated by electron cyclotron resonance (ECR) plasma process using gas mixtures of silane, methane, argon, and hydrogen. The resultant tips have nano-scale apexes, approximately ~1 nm, with high aspect ratios, nearly ~15, which were achieved by simultaneous SiC nano-mask formation and dry etching during ECR plasma process. Next, the nickel mold of nanostructures is made from silicon nanostructures through the electroforming process by using Nickel Sulfamate. The total thickness of the nickel mold is 120 μm after a 10-hour-long electroforming process. The nanostructures of 100 nm diameter holes are successfully obtained. Nanoimprint process is proceeded by the nickel mold and the reflectance of the PMMA after imprinting at 160 °C has the lowest value, 0.2 %, compared with the other results for the incident optical wavelength of 550 nm. The large-area imprint mold with high-aspect-ratio nanotip arrays of sub-micron diameter is fabricated and is proofed by the optical application.
A Study of Process Parameter Optimization for Passive Component Precision Extrusion
Authors: Lin Wei Shin , Lee King Sun , Huang Shih Miao , Jou Rong Yuan , Lin Jui Chang
Published: March 2009

Chips scraping each other during transportation, and chips coming into contact with
water or air will cause oxidization resulting in poor quality products. The chips need to be well
packed and to be protected from the environment. The method of Surface Mount Component
(SMC) packing using plastic carrier tape can reduce chip damage. This study focuses on the
extrusion process parameters optimization of plastic carrier tape. Because each extrusion process
produces 270 pieces of carrier tape, the tape size is 1.35mmX2.25mmX1.35mm and is extremely
difficult to reach the tolerance standard. This study utilized a practical test to explore various factors
on the quality of the carrier tape, such as the rotational speed of extruder screw motor and extrusion
mold; the negative pressure of extrusion mold; and the temperature of the extrusion mold. These
experiments could find out an optimal extrusion process.
The Optimal Process Analysis for Precision-Drilling of Mold Steel SKD61
Authors: Lin Wann Yih , Lee Bean Yin
Published: March 2009

The Taguchi method is regarded as a powerful tool to design optimization for quality. In
this study, it was used to find the optimal cutting parameters for precision-drilling operations. The
cutting parameters include guiding drilling, spindle speed, feed rate, stepping amount, number of
steps and cutting fluid. The considered characteristics of performance are tool life, and the variation
of drilled hole-diameter.
Taguchi Method and Orthogonal Array were applied to the experiments of precision-drilling so
as to allocate the corresponding processing parameters. The obtained results were then evaluated by
Response Table, Response Chart, and Analysis of Variance methods (ANOVA) to acquire the
optimal processing parameters. These were further confirmed by experiment. Finally, the analysis
of the precision-drilling process applied for mold steel SKD61 shows that this approach can greatly
improve the drilling performance of a small-drilling process.
Performance Assessment of Design Electrode in Ultrasonic-Aided of Freeform Surface Finishing
Authors: Pa Pai Shan
Published: March 2009

The most effective geometry for design electrode and the advantage of low cost equipment in ultrasonic-aided electrochemical finishing for a freeform surface following turning machining was investigated. The proposed design process used an effective electrode instead of the mate electrode as in conventional ECM. Hence higher electrical current is not required when the effective design electrode is used to reduce the response area. Through simple equipment attachment, electrochemical finishing can follow the traditional cutting on the same machine. The controlled factors included the chemical composition and concentration of the electrolyte, the initial gap width, the flow rate of electrolyte, workpiece rotational speed, and die material. The design electrode is primarily discussed among the factors affecting the electrochemical finishing. The experimental parameters were current rating, electrode feed rate, frequency , power level of ultrasonics, and electrode geometry. The effective design electrode with small wedge angle and small edge rounding radius had an optimal value for higher current density and provided larger discharge space, which produce a smoother surface. The electrode of globe-shape with small radius performed best in the finishing process. The electrochemical finishing needed only a short time to make the workpiece smooth and bright and save the need for the precise process of traditional machining. The ultrasonic-aided electrochemical finishing is recommended for the finishing process of the freeform surface.
Design of Ion Beam Figuring Machine for Optical Mirrors
Authors: Jiao Chang Jun , Xie Xu Hui , Li Sheng Yi , Zhou Lin , Dai Yi Fan
Published: March 2009

Ion beam Figuring (IBF) of optical mirror is a polishing process based on CCOS with the
application of ion sputtering effects. The material removal mechanism is in the atom scale, which
can enhance the precision of the target surface to tens of nanometers. Without contact, this process
can also promote the subsurface quality. In this paper, the Ion Beam Figuring Machine (IBFM) is
introduced，which realizes the relative motion between the target surface and the ion source.
Firstly, we describe the design method, the machine configuration and principal technical
parameters. With the configuration and motion ability described, we introduce different scanning
modes for surfaces of different scales respectively. Secondly presented is the precision analysis
method for IBFM. Based on the CCOS principle, the relation between the convergence rate and
positioning errors are deduced. This relation describes the precision requirement of machining
process. Finally, the postposition algorithm of IBFM is analyzed. According to coordinate transition
and rotation, the general transfer model for different scanning modes is given.
Study on CAN-Based Lighting and Identifying System for Automobiles
Authors: Chen Fu Long , Fan Xiao Ya , Ma Gui Chun
Published: March 2009

Head lamps, tail lamps, side lamps, roof lamps, alarm signal lamps and other lamps of an
automobile constitute a whole lighting system, and identifying devices constitute a guarding system
against theft and alarm. In traditional designs, each lamp is independent and controlled artificially
by persons, and the automobile cannot show maintenance men which lamp is broken-down and
needs mending or replacing. The lamp is either ON or OFF, and its luminance can be adjusted
neither automatically nor artificially so that much energy goes to waste. Moreover, lighting system
is isolated from identifying system so that they are difficult to manage by a uniform system.
Currently, identifying systems of many automobiles key system, door-controlling system, UHF
sending/receiving system, alarm system and so on. Once the key is lost or stolen, those persons that
have not the ownership can also open the door of the car with it. In this paper, an ISO Standard
(ISO 11898) for serial communication- CAN is introduced. Through CAN micro-controller
provided by ATMEL, each lamp of lighting system is a component and can be interconnected.
Identifying system, in which fingerprint encryption technique is utilized, can also be interconnected
with lighting system. This system can be controlled completely, and has some advantages such as
smartness, security, low power, low cost, etc.
The Electrochemical Micro-Fabrication Method for Micro-Scale Flow Channels
Authors: Lee Shuo Jen , Lee Yu Ming , Lee Chi Yuan , Lai J.J. , Yang K.T. , Kuan F.H.
Published: March 2009

Due to lack of desirable mechanical properties of silicon substrate; the current trend of
micro-fabrication technology is towards metallic materials. In this study, the electrochemical micromachining
(EMM) technology is developed to fabricate micro-scale flow channels on thin metallic
316L stainless steel plate. The cathode electrode, the tool, is the mirror image of flow channels. It
was produced by the MEMS and UV-LIGA technology and the size is 200μm in width and 500μm
in height for the intension to fabricate a serpentine flow channel of 200μm in both depth and width.
Because of the electrode size, the process control parameters and geometrical features surpassed
conventional and CMOS methods. The flow channels on 0.6mm thick SS 316L plates were
fabricated by EMM process within 30 seconds with effective area of 625mm2. The dimensions of
flow channel were varying from 1504m to 5004m in width and about 2004m in depth. The results
demonstrate the EMM technology produces good quality metallic flow channels efficiently.
Diffraction Effect in Proximity Printing of Circular Aperture Array
Authors: Tsai Jhy Cherng , Hsieh Meng Yun , Yang Hsi Harng
Published: March 2009

Proximity printing is one of the lithographic processes used in fabricating semiconductor,
micro optoelectronic components and micro electro-mechanical systems to transfer mask pattern to
the substrate. This research investigates the cause of pattern distortion based on the analysis of
diffraction effect of light beam due to the gap between the mask and the photo resistant in the
proximity printing process. The Huygens-Fresnel diffraction theorem is first employed to derive the
diffraction effect. It shows that irradiance decreases as the gap increased, which is consistent with
practice. Further investigation shows that shading area can be exposed, even with a small gap, due
to the diffraction effect that makes the exposed image imprecise. A deeper analysis on the
diffraction effect in microlithography of proximity printing with single-aperture, dual-aperture, and
multi-aperture masks is investigated. It shows that the contrast irradiance between the exposed and
the shading regions becomes closer as the gap increases. This makes the boundary of image become
vague and causes the exposed image to be distorted. Experiments are then designed and conducted
to verify the derived results. Experimental results using φ80μm circular single-, dual- and multiaperture
masks showed that the boundary of adjacent circular apertures begins to crossover with
each other when the gap reaches 240μm. When the gap increases to 360μm, interference between
adjacent circular apertures becomes stronger that results in hexagonal images. This shows that
experimental results are consistent with simulations from theoretical analyses. The main
contribution of this research is to analytically find the distortion of image in proximity printing due
to diffraction effect and to verify the theory by experiments.
Mechanical Solutions for Hot Forward Extrusion under Plane Strain Conditions by upper Bound Method
Authors: Domingo Rosario , Camacho A.M. , Rubio Alvir E.M. , Sebastián M.A.
Published: March 2009

This paper present a study focused on hot forward extrusion by upper bound method. In particular, hot forward extrusion of plates through square face dies under plane strain conditions. Slater defines the models used for large fractional reduction. Different models have been taken in account; they are dissimilar in relation to the dead metal zone (if covers or not the entire die face, partially or totally). Triangular rigid patterns of velocity discontinuities have been validated by analytical methods and a range of use for the selected configurations has been established. This methodology has been applied to other process with good results. Thus, the mechanical parameters analysed are fractional reduction, dead metal zone, length die and friction. Finally the calculation of the energy has been achieved by upper bound method. The results allow researching an optimisation of use of upper bound method in hot forward extrusion.
Numerical Optimization of Bearing Length in Composite Extrusion Processes
Authors: Kloppenborg Thomas , Schikorra Marco , Schomäcker Michael , Tekkaya A. Erman
Published: March 2009

The decrease of the bearing length in extrusion processes results in increasing of the
material flow and offers, through this, the possibility for manipulation and optimization. This paper
presents a simulation based optimization technique which uses this effect for optimizing the
material flow in direct extrusion processes. Firstly, the method is used in a multi-extrusion process
with equal pitch circle profiles, then in an extrusion process of an asymmetric profile. Furthermore,
a composite extrusion process is analyzed where endless wires of high strength steel are embedded
in a base material of aluminum. The insertion of reinforcement elements into the base material flow,
especially within the small ratio between profile thickness and the reinforcement diameter, can lead
to significant local disturbances inside the die, which result in undesirable profile defects. Hence,
the simulation-based optimization method is especially used to optimize inhomogeneous wall
thicknesses in composite profiles.
Aluminum Rod Extrusion and Material Modeling
Authors: Moe P.T. , Khan Yawar Abbas , Valberg Henry Sigvart , Støren Sigurd
Published: March 2009

The article presents an outline of a scientific approach for testing constitutive relations for
the aluminum extrusion process. By comparing ram force, container friction, die face pressure,
outlet temperature measurement during rod extrusion with corresponding simulated data, inferences
can in principle be drawn with respect to the validity models. The paper indicates that simulation
results from the 2D ALMA2π program are in fair agreement with measurements during extrusion of
AA6060, but more work needs to be done to control thermal conditions during extrusion.
Hot Workability and Constitutive Equations of ZM21 Magnesium Alloy
Authors: El Mehtedi Mohamad , Balloni Luigi , Spigarelli S. , Evangelista E. , Rosen G.I.
Published: March 2009

One of the most challenging activities for magnesium industry is to increase productivity
by introducing cost-effective processes. While die-cast magnesium alloys are in worldwide use,
even in the demanding sector of automotive industry, where cost is the major asset, wrought
magnesium alloys still not widely available. The aim of the present study was to evaluate the high
temperature response by torsion testing of a ZM21 alloy, to calculate the constitutive equations to
be used in FEM simulation of the extrusion process. The ZM21 alloy that was considered in the
present study was Direct-Chill casted by Alubin Ltd., Israel. Torsion tests were carried out in air on
a computer-controlled torsion machine, under strain rates ranging from 10-2 to 5 s-1 and
temperatures from 200 to 400°C. The equivalent peak flow stress was related to temperature and
strain rate by means of the conventional power-law and by the sinh equation. The microstructure of
the alloy, even at 300°C, appeared largely unrecrystallized, with elongated grains; also at 400°C,
the structure is more equiaxed, but elongated structures still appears.
Luminescence Sensing of Temperature in Oxides
Authors: Clarke David R.
Published: March 2009

The measurement of temperature based on the characteristic lifetime decay in
luminescence intensity of dopant ions following excitation is described with illustrations drawn from
europium doping in yttria-stabilized zirconia. The method is particularly attractive for making
measurements in a temperature gradient, such as those in thermal barrier coatings.
Preparation and Microstructural Evolution of Sol-Gel-Derived Enstatite Fibers
Authors: Tsai M.T. , Tsai P.J. , Chang H.C.
Published: March 2009

Homogeneous and transparent enstatite fibers were prepared via the sol-gel process of metal alkoxide precursors. The gel-to-ceramic conversion was characterized. The solution compositions had a significant influence on the microstructural evolution of gel fibers. Infrared studies indicated that bidentate bridging ligands were formed between acetate and metal ions, which enhanced spinnability remarkably. The as-drawn fibers were essentially microporous. On heating to 800 oC, enstatite ceramic fibers exhibited mesoporous structures with nanocrystals in size. The optical transmittance of enstatite ceramic fiber in the visible range was around 90 % after heating at 800 oC.
Effects of Pyrolysis Temperatures on the Microstructure and Mechanical Properties of 2D-Cf/Si-O-C Composites
Authors: Liu Jing Yu , Jian Ke , Chen Zhao Hui , Ma Qing Song , Wang Song
Published: March 2009

Two-dimensional carbon fiber cloth reinforced silicon oxycarbide (2D-Cf/Si-O-C) composites were fabricated with silicone resin (SR) as precursors, ethanol as solvent and SiC as inert fillers by precursor infiltration pyrolysis (PIP). Effects of the pyrolysis temperatures in the first cycle and the last but third cycle on the microstructure and mechanical properties of 2D-Cf/Si-O-C composites were investigated. The results showed that, when the pyrolysis temperature of the first cycle was 1200°C, 2D-Cf/Si-O-C composites exhibited good mechanical properties, which can be attributed to the better fiber/matrix interfacial bonding. When the pyrolysis temperature of the last but third cycle was 1400°C, the mechanical properties of 2D Cf/Si-O-C composites were further enhanced. The flexural strength and fracture toughness of the composites reached 263.9MPa and 12.8 MPa·m1/2, respectively.
Time-Dependent Mechanical Behaviors of Polyamide 6/Nano-SiO2 Composite
Authors: Zhao Rong Guo , Luo Wen Bo
Published: March 2009

The uniaxial tension under various strain rates, creep under various sustained loads, and equalamplitude-
strain loading and unloading tests are carried out at room temperature with polyamide 6/nano-
SiO2 composite specimens. According to the elasticity recovery correspondence principle, the recovered
elastic stresses (strains) in the case of prescribed strain (stress) history are calculated, and the instantaneous
elastic constitutive equations are deduced. The nonlinear viscoelastic constitutive relations in single
integral form on the basis of the instantaneous elastic constitutive equations are constructed and applied
to model the current stress (strain) responses of polyamide 6/nano-SiO2 composite. The theoretic results
agree well with the experimental data, which demonstrates that the single integral constitutive relations
used in this work can accurately simulate the physical nonlinear viscoelastic properties of polyamide
6/nano-SiO2 composite. Finally, the creep curve at higher stress level is horizontally shifted along logarithmic
timescale using a stress shift factor in terms of the time-stress superposition principle and superposed
on that at relative lower stress level to form a master creep compliance curve that spans a longer
timescale interval than the short-term test curve does, which suggests that TSSP provides an accelerated
characterization method for the long-term creep performance of polyamide 6/nano-SiO2 composite.
Wear Mechanism and Self Lubrication of Engineering Ceramics at Elevated Temperatures
Authors: Xiao Han Ning , Yin Ji Xiang , Senda Tetsuya
Published: March 2009

Friction and wear tests of Al2O3 and SiC were conducted from room temperature to 1200°C
both in air and in vacuum. Results show that the wear mechanism of Al2O3 is dominated by micro
fracture, debris abrasive and delamination at temperatures below 600 °C, while is controlled by plastic
deformation and recrystallization among 600~1200 °C, resulting in an obvious decrease of wear loss. The
wear rate and surface microstructure of SiC are closely depending on the testing temperature, atmosphere
and contact pressure. Oxidation of SiC at elevated temperatures plays important role on the wear rate. Self
lubrication of both Al2O3 and SiC at high temperatures was observed, which is mainly depending on the
formation of a specific surface layer composed of nano-particles or very thin glassy film.
Influence of C and Al Addition on Microstructure and Mechanical Properties of Ultrafine TiCN-Based Cermets
Authors: Ni Xian Juan , Qi Long Hao
Published: March 2009

In this paper, the TiCN-based cermets were fabricated with ultrafine TiCN, metal binders and carbide additives. Different content of C and Al were separately added to eliminate the oxygen contamination. The composition of the mixture was TiCN-10Mo-20WC- 20Ni-xC/Al. Effect of the C and Al addition on microstructure and mechanical properties was investigated. Results indicated that cermets with carbon addition had higher relative density and more homogenous microstructure while the Al addition had the opposite effect. Proper addition of carbon improved the mechanical properties.
Thermal Conductivity of Sol-Gel Bonded Castables
Authors: Cao Feng , Wang C.Y. , Tang P.S. , Lu C.Y. , Chen H.F. , Long Shi Gang
Published: March 2009

The silica-alumina sol bonding agent, prepared by the sol gel route from ethyl silicate and
aluminium isopropanol, was utilized in the refractory castables. The influence of structure on the heat
transfer has been investigated using different sorts of refractory matrix. The results indicated that the
heat conductivity of sol-gel bonded castables was considerably affected by their structure. The phase
composition of matrix, porosity, pore size distribution and pore size structure were the most important
factors. Thermal conductivity has been measured from the ambient temperature up to 1250 °C. The
influence of crystalline phases and the glassy phase formation and the influence of the pore size
distribution on the thermal conductivity were also described in this work.
Molten Salt Synthesis of CaCu3Ti4O12
Authors: Chen Ke Pi , He Yong , Liu Dong Yu , Liu Zong De
Published: March 2009

CCTO powders were prepared by using molten salt method in the NaCl-KCl system. The
effects of temperature and holding time on phase compositions, particle morphology and size have been
investigated by X-ray diffraction, scanning electron microscope and laser particle size analyzer. Using
CaCO3, CuO and TiO2 as starting materials, CCTO compound could be synthesized at any temperature
from 800oC to 1000oC in the NaCl-KCl system. The average particle size increased obviously with the
increasing of temperature above 850 oC. Holding time had great effect on grain size and morphology.
Effects of the Replacement of Ti by Zr on the Dielectric Properties of CaCu3Ti4012 Ceramics
Authors: You Jing Han , Chen Qing Dong , Ju Wei Wei , Li Li Ben , Chen Kai
Published: March 2009

CaCu3Ti4O12 and CaCu3Ti3.9Zr0.1O12 ceramics were prepared by the traditional solid-state
reaction method and the dielectric properties were investigated. Comparison of the results of the two
samples examined indicated that the partial replacement of titanium by zirconium in the system
CaCu3Ti4O12 may result in different changes of the dielectric constant and dielectric loss. For these
experimental phenomena possible explanations and predictions also have been presented.
Bioactive and Stability of Calcium Phosphate-Polypyrrole Composite Coatings by Electrochemical Deposition
Authors: Li Mu Qin , Qu Li Jie , Ma Chen , Yang Shi Qin
Published: March 2009

This study examined the bioactive and stability of calcium phosphate- polypyrrole(ppy) composite coatings on titanium alloys by electrochemically deposition in simulated body fluid (SBF). Change of coatings mass and SBF pH during coatings soaked in SBF indicated that ppy reduces the decomposition of coatings. The surface morphology of coatings characterized by SEM showed that the stability of composition coating was superior to that of single coating. XRD indicated that ppy induces CO3 2- enter calcium phosphate coating, which showed that the composite coatings possess better bioactive. Thus, this electrochemical deposition provides an effective method of ppy incorporation at physiological temperature, which can offer excellent bioactive and stability of coatings, with a potential for sustained release of therapeutic agents as required for metallic implant fixation.
Bioactive Porous Film Produced on Titanium Substrate by Micro-Arc Oxidation
Authors: Ma Q. , Wang Y.J. , Ning Cheng Yun , Cheng Hai Mei , Yin Zhao Yi
Published: March 2009

Porous bioactive thin film on commercially pure titanium substrate was prepared by micro-arc oxidation (MAO) in electrolytic solution, which contained calcium acetate, β-glycerol phosphate disodium salt pentahydrate (β-GP) and lanthanum nitrate. The phases and microstructure of the bioactive films were examined by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometer and electron probe microanalysis. The results showed that: (1) porous bioactive films with about 10μm were formed on titanium substrate by MAO; (2) phases of the thin films were hydroxyapatite, anatase and rutile; (3) elements of Ca, P, and Ti of films were identified by EDS.
Residual Stress and Reliability of Glass/Alumina Dental Bi-Layer Ceramics
Authors: Bao Yi Wang , Qiu Yan , Bu Xiao Xue , Liu Yi Hong , Shen Zhi Jian
Published: March 2009

Glass-alumina bi-layer composite was widely used as dental materials, the reliability and
mechanical properties are very important for its practical application. In this work, residual stresses in
dental glass-alumina composite and failure mechanism were investigated through finite element analysis
and 3-point and ball-on-ring bending tests, respectively. The mechanical behavior of the dental material
was studied using the bending tests and indentation method. Small bi-layer disk specimens were prepared
for the axis-symmetrical tests using a set of small device in a universal tester. The results indicate that the
difference in thermal expansion coefficients between two layers lead to residual stresses in both layers,
and the stresses distribution depends on the thickness ratio and temperature difference. Furthermore, a
proof testing method was proposed to estimate the workability and reliability of the dental ceramics.
An Investigation of Structure and Wear Properties of TiN/NbN Films Deposited by Reactive Magnetron Sputtering
Authors: Liu Chien Cheng , Weng Ming Hang , Wang Chien Tang , Chen Jheng Hong , Chou Yung Chih , Yaw Huai Wei
Published: March 2009

TiN/NbN multilayers on steel substrates (SKD11) are produced using DC magnetron sputtering process. The multilayer obtained are characterized in composition by means of X-ray diffraction techniques, Microhardness and adhesion to the substrate were studied by atomic force microscopy and scratch tests. The morphological analysis and coating structure are studied using scanning electron microscopy, and atomic force microscopy. The film thickness is measured by a stylus profiler (XP-2 stylus profiler). Wear tests were performed on pin-on-disk configuration and dry sliding conditions, at 5N load by using hardened steel ball. On mechanical properties, higher Young’s modulus and hardness values follow to increase the TiN/NbN layers number. The multilayer films of 64 layers at 500°C 1h annealing indicated that the microhardness and Young’s modulus had the highest values.
Magnetite Nanoparticles Surface Coating SiO2 and Magnetic Properties Evaluation
Authors: Ju Dong Ying , Bian Pei , Qing Ge Letu , Lu Da Ling , He Hong
Published: March 2009

Magnetite nanoparticles were obtained by liquid phase precipitation method in which the pH
value of [FeCl2⋅4H2O], [FeCl3⋅6H2O] and [NaOH] solution were controlled. Then the magnetite
nanoparticle were scattered in water solution and put in [Na2SiO3] and [HCl], the resultant of reaction
SiO2 can be coated on magnetite nanoparticles surface. The morphology and magnetite properties of the
coated nanoparticles were evaluated by XRD, TEM, FTIR and VSM. The SiO2 thin film with nanometer
size was coated on surface of nanoparticle, so that the magnetic value is decreased with the coating
thickness increasing.
Study on Coating Method to the Stainless Steel Substrate Top of Ag/Al2O3 Catalyst System
Authors: Kishida Satoshi , Ju Dong Ying , He Hong
Published: March 2009

A study of a catalyst for NOx reduction used for a diesel engine of cars is done frequently
currently. In the recent studies, Ag/Al2O3 catalyst system is considered to be a candidate for practical use.
The ceramics molding body (ceramics honeycomb etc.) is used as a border brim of these catalysts usually.
However, there is a problem. Strength to thermal shock is low. Moreover, it is not easy to go up in the
center part until the catalyst operating temperature because thermal conductivity is bad and is obstructed
working of the catalyst to the first stage of the reaction for that. In this research, the Ag/Al2O3 catalyst
system was coated to stainless steel (SUS304) substrate that forming it is easy and heat conduction rate is
good. The aluminum nitrate was used as a binder. After the binder is dissolved in the ion exchange water,
the stainless steel substrate coated Ag/Al2O3 catalyst is sintered. In order to optimize coating conditions,
the heating temperature, the sintering time, the density of the binder and the amount of the coating powder
addition as well as the dip coating frequency were changed, respectively.