bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Analysis of Rigid-Body Mechanisms Mounted on Flexible Support Structures — Planar Case
Authors: Sun Huai Ku , Chen Cun Gin , Shen Yu Chen
Published: March 2009

Computer-aided analysis of rigid-body mechanisms is combined with the finite element analysis of flexible structures to develop a computer model and derive the equation of motion, incorporating the Lagrange multiplier, to be used in the dynamic analysis of multi-rigid-body mechanisms mounted on flexible support structures. The resulting equations are solved by numerical integration. Predicting and analyzing the performance of the full system, including the motion of the system components and the forcing condition, during the engineering design process will promote the
success of the entire system. Finally, a machine gun system with a flexible mount is given as a numerical example. The results reveal that the interaction between the rigid-body mechanisms and its flexible support structures importantly determines the performance of whole system. This study considers only the planar case. Our future work will propose a more complicated fully three-dimensional model.
Parametric Study of Spherical Micro-Lens Array
Authors: Shyu Ruey Fang , Pan C.T. , Lin S.C.
Published: March 2009

This study presents a concept to fabricate micro-lens devices using high-aspect-ratio lithography, extra-hardness electroplating, and hot embossing processes. A bath of electroplating electrolyte will be formulated to fabricate micro-optics mold inserts with extra-hardness Ni-Co alloy. It is a novel method to increase the life of the mold insert during fabricating micro-lens devices. With this high hardness, the mold inserts can resist high abrasiveness and wearness so as to extend the mold cycle life and reduce the idle time of replacing mold plates during fabrications. Therefore, the process of fabrications of micro-lens can be more cost-effective. In this study, parametric effects of reflow time, and temperature on micro-lens profiles will be characterized and discussed. Finally, the optical properties such as focal length of developed micro-lens will be measured and tested.
A Micromachine-Based Flow Cytometer Chip Integrated with Micro-Pumps/Valves for Multi-Wavelength Detection Applications
Authors: Chang Chen Min , Hsiung S.K. , Lee Gwo Bin
Published: March 2009

This study presents a new micromachine-based cell counting and sorting system capable of multi-wavelength detection for biological applications. Chip-based flow cytometers have been extensively investigated recently. Several unique features have been integrated on this new cell-analysis system. First, a series of new serpentine-shape pneumatic micro-pumps were used to drive sample and sheath flows and generate a hydrodynamic focusing effect. The control of fluids
could be achieved with ease by using this approach. Multiple embedded optical fibers were then used to transmit the light source and collect induced fluorescence signals in and out of the chip device. Cells labeled with different fluorescent dyes could be then individually detected by corresponding fibers using lasers with different wavelengths. Finally, three pneumatic micro-valves
downstream were used for cell sorting. The developed micro flow cytometer could be used for fast analysis of cell-related bio-medical applications.
Optimization of Parameters Affecting Tool Wear in Titanium Acetabulum Cup Forging
Authors: Lee Rong Shean , Jou Jin Long
Published: March 2009

Titanium is an attractive material for orthopedic implants, although it is expensive and
difficult to manufacture. Hot forging is usually used, but the tool life is always not good since the forging tools sustain higher temperature and the working pressure induces wear. In this research proposes a procedure to obtain forging parameter design optimization considering tool wear using a combination of FEM simulation and Taguchi method. A modified Archard’s wear model is used to predict the tool wear. This procedure is used to evaluate titanium artificial acetabulum cup forging.
Based on the minimum tool wear, but maintaining the microstructure required to satisfy the properties needed by orthopedic implants, the titanium acetabulum cup development is successful and the tool life is better than our expectations.
Application of FSQP to Inverse Estimation of the Constitutive Constants and Friction Coefficient in the Nosing Process
Authors: Lu Yuung Hwa , Yeh Fung Huei , Li Ching Lun
Published: March 2009

This paper combines Feasible Sequential Quadratic Programming (FSQP) and
elasto-plastic finite element method to perform the inverse estimation of the material constitutive constants and friction coefficient in the nosing process. The aim is to improve the accuracy of constitutive constants and working parameters in the classical analysis based on the material flow homogeneity or trial and error. In the prediction of the friction coefficient at the interface between metal and tool surface, the simulated load, calculated from the optimal material constants, shows
good coincidence with the experimental load when the optimal friction coefficient is reached. The investigation of these inverse models identify that the combination of FSQP and elasto-plastic finite element method can supply a useful optimal approach in the industrial application.
Influence of Die Material upon Formability and Galling of Hot-Dip Galvanized Steel Sheets
Authors: Lin Yu Li , Li Hshah Shun , Hwang Hou Sheng
Published: March 2009

Stretching forming test was utilized to evaluate the influence of die material upon
formability and galling of hot-dip galvanized steel sheets. SS41 and SKD11 were used as the substrate of die materials which CrN, TiN and DLC (diamond like carbon) were coated on SS41 and SKD11 substrate. It was found that die with coated materials performs better than that without coated materials in terms of formability and friction. Moreover, DLC coated die material shows the best
performance on formability, friction and galling comparing to other coated materials.
A Study on the Effects of Mass and Velocity Factor for the Dynamic-Explicit FEM in the Upsetting Process
Authors: Liu Chun Ho
Published: March 2009

Currently, the numerical simulations of metal forming are developed rapidly and widely. In this investigation, a dynamic-explicit FEM code, LS-DYNA, is adopted. Attention on applications of the velocity and mass scaling techniques for the quasi-static upsetting process are modeled. With the differences being variations in the die and punch velocities, the material density, and the mesh type,
their effects on the predicted load-reduction height are assessed. Through comparison with experiments, the numerical results have a same tendency as in test works. The influences of the velocity and mass factors are presented, the usage of these scaling factors at proper time also discussed.
Predictions of the Minimum Amounts of Preforming in the Radial Extrusion of Tubular Components
Authors: Lin F.C. , Lin Shen Yung
Published: March 2009

Both the minimum relative depth of die cavity and the minimum amount required in preforming are determined to produce a defect-free product of tubular component in the preforming technique of radial extrusion in this study. This scheme is based on the least amount of material dissipation in radial extrusion of tubular component. A finite element based code is utilized to investigate the effects of various relative depths of die cavity, different percentage of preforming and relative height reduction on the material flow characteristics resulting in the movements of the defects
locations. The abductive network is also applied to synthesize the data sets obtained from the numerical simulations. Consequently, a prediction model is established for organizing the minimum relative depth of die cavity and the related minimum amount required in preforming of the tubular
component for different end strokes of deformation.
Autoresonant Tuning and Control in Ultrasonic Vibration Assisted Drilling Process
Authors: Chen Yu Chieh , Liao Yunn Shiuan , Fan J.D.
Published: March 2009

This paper presents an optimal cutting-parameter design of heavy cutting in side milling for SUS304 stainless steel. The orthogonal array with relational analysis is applied to optimize the side milling process with multiple performance characteristics. A grey relational grade obtained from the grey relational analysis is used as a performance index to determine the optimal cutting parameters. The selected cutting parameters are cutting speed, feed per tooth, axial depth of cut, and
radial depth of cut, while the considered performance characteristics are tool life and metal removal rate. Experimental results have shown that cutting performance in the side milling process for heavy cutting can be significantly improved through this approach.
Ultrasonic Welding of Aluminum and Silicon Wafer
Authors: Shu Kuen Ming , Shih Hung Rung
Published: March 2009

There are several types of welding method to join metal and ceramic. This paper gives a description of an experimental study of the ultrasonic welding of aluminum wire and silicon wafer under the conditions of the frequency of ultrasonic vibration f = 38000Hz, the applied duration T=0.2-1.5 sec, and the welding force Ps =40-140 gf.
In this study, vacuum deposition was first applied to deposit surface modification aluminum on silicon wafer, then ultrasonic welding processes were investigated to join aluminum wire and modified silicon wafer. Based on the results of the microstructure observation and tensile test, it is believed that the joining ability can be improved under optimum welding condition.
A New Knowledge Discovery Model for Extracting Diagnosis Rules of Manufacturing Process
Authors: Tsai Ying Chieh , Cheng Ching Hsue , Chang Jing Rong
Published: March 2009

The knowledge obtained from the experience of monitoring manufacturing process is
critical to guarantee good products produced at the end of manufacturing line. Recently, many methods have been developed for the described purpose above. In this paper, a new knowledge discovery model based on soft computing is proposed. The proposed model contains a new algorithm Modified Correlation-based Feature Selection (MCFS), a new algorithm Modified Minimum Entropy Principle Algorithm (MMEPA), and Variable Precision Rough Set Model (VP-model). After
conducting a real case of monitoring the process of manufacturing industrial conveyor belt, some advantages of the proposed model are that (1) MCFS can quickly identifying and screening irrelevant, redundant, and noisy features for data reduction; (2) MMEPA can objectively construct membership functions of fuzzy sets for fuzzifing the reduced dataset; (3) VP-model can extract causal relationship rules for controlling product quality; (4) Extracted rules by the proposed knowledge discovery model are easily understood and interpretable.
The Optimum Selection of a Parting Line for an Injection Mould Using FEM Database Management and Application Techniques
Authors: Lin Jui Chang , Lin Shen Yung , Lee K.S. , Lu Ming Fang , Yen Chia Ming
Published: March 2009

This paper presents a methodology for obtaining an optimal parting line of an injection
mould based on FEM analysis and managements. This research utilizes Taguchi’s method to design a DATABASE for the gate position and warping of parts. Firstly, it sets up an injection model via a CAD system, and secondly, utilizes FEM to analyze the warp of the injection mould in different gate positions. Because of different gate positions, the parts experienced extreme differences in the amount of warping. This paper applies the neural network (abductive network) to build the relationship (database) between the gate position and amount of warp. Engineers can use this
database without recourse to a CAD model and FEM solution to predict the amount of warping at different gate positions. This procedure saves time in building CAD models and on carrying out FEM analysis. The optimal parting line parameters can then be reached through a Simulated Annealing (SA) optimization algorithm. The methodology uses multi-objective function criteria, with a performance index to obtain perfect parts. This method of database management can offer various design fields of injection mould (e.g., design of gating and runner, and design of cooling
system). It already achieves real optimization of design for injection moulding.
Absorption of a Micro-Particle for Laser
Authors: Ho Ching Yen , Wen Mao Yu
Published: March 2009

This paper investigated the absorption of a micro-particle irradiated by laser.
Micro-particles usually appear within the plasma induced by a laser or powder in the process of laser cladding. These particles are assumed to be spherical and neutral (no surface charge). Laser-particle interactions involve scattering, refraction, and diffraction phenomena. Refraction and diffraction can enhance radiation absorption. The complex optical indexes of material and size parameters of
micro-particles characterize the absorption of particles in these materials processing. The electromagnetic wave theory and geometrical optics approach were utilized to analyze the absorption in the particle. The errors between these two methods were discussed for different indexes of absorption and size parameters. The compatibility of geometrical optics approach for a small particle
is also presented.
Evaluation of Permeability of Interdendritic Channels for Al-Cu and Sn-Pb Alloys
Authors: Melo M.L.N.M. , Santos R.G.
Published: March 2009

A particularly important defect related with solute segregation during solidification is the microporosity, which influences mechanical properties of castings. Considering only the formation of porosity due to shrinkage, during directional solidification, it is necessary a flow of liquid metal into the interdendritic channels to compensate for metal contraction, and pores are formed when the pressure drop in the liquid flow at a point within the mushy zone exceeds the pressure acting at this point. The increase in roughness of the interdendritic channels, caused by the successive ramification of the dendrite arms promotes a pressure drop inside the channel. In this paper a model developed by the authors is used to predict the permeability in directional solidification of Al-Cu and Sn-Pb alloys. From comparisons with experimental results models were choose to estimate primary and secondary dendrite arms spacing and applied to calculate the variation of permeability in directional solidification. From these results, applying a numerical method the pressure drop in the interdendritic channels was determined for the different alloys to analyze the influence of the composition of the alloy in the possibility of pore formation.
EBSD Study of ZnAl25 Alloy Inoculated with ZnTi4 Master Alloy
Authors: Krajewski Witold K. , Greer A. Lindsay
Published: March 2009

The microstructure of cast Zn-25wt%Al alloy inoculated by addition of a Zn-4wt%Ti master alloy (ZnTi4) has been studied using scanning electron microscopy and electron back-scatter diffraction (EBSD). It is found that Ti(Al,Zn)3particles act as nucleation centres for grains of the primary solid solution of Zn in Al (α' phase). The Ti(Al,Zn)3particles evolve in melt from the TiZn3particles in the ZnTi4 master alloy. EBSD shows that α' phase dendrites are in the same crystallographic orientation as the Ti(Al,Zn)3particles on which they nucleate. It is also found that some of the Ti(Al,Zn)3particles do not have any well-defined crystallographic orientation relationship with the α' phase. These particles were probably pushed and then engulfed by growing α' grains which had already nucleated on other particles.
Prediction of the Formation of an Equiaxed Zone Ahead of a Columnar Front in Binary Alloy Castings: Indirect and Direct Methods
Authors: McFadden Shaun , Browne David J. , Banaszek Jerzy
Published: March 2009

The as-cast properties of components with a columnar grain structure are very different from those with an equiaxed one. Under certain solidification conditions, zones of both structures can occur in an alloy casting; the boundary between the zones is the columnar-to-equiaxed transition (CET). A front-tracking model of dendritic solidification has been developed, which can predict the nucleation and growth of solid in undercooled liquid during a casting process. The growth process is
described by dendrite tip kinetics, and is fully coupled to a fixed-grid control volume model of heat transfer during solidification. Using the front-tracking model, two methods for predicting the likelihood of an equiaxed zone forming ahead of a columnar front have been formulated, namely, an indirect method and a direct method. The indirect method is based on modelling the growth of the columnar front in the absence of equiaxed nucleation. The bulk liquid undercooling is monitored and an equiaxed indicator is calculated at each time step based on the extent of such undercooling at that time. The equiaxed indicator is a measure of the relative likelihood of an equiaxed zone forming. In the direct method nucleation and growth of individual equiaxed grains is treated ahead of the advancing columnar front. In this case, if impingement of neighbouring fronts is treated, the simulation to complete solidification will yield the macrostructure and the CET. In this paper, details of both methods of equiaxed prediction are presented. Results from the indirect method are
compared to experimental results found in literature and agreement is found.
Segregation Effects and Phase Developments during Solidification of Alloy 625
Authors: Højerslev C. , Tiedje Niels , Hald J.
Published: March 2009

The solidification behaviour of pure Alloy 625, and Alloy 625 enriched respectively in iron and carbon, was investigated in situ by hot-stage light optical microscopy. Using this technique planar front solidification for distances of several hundred microns was facilitated. After solidification, the material that experienced planar front solidification corresponded accurately to that of dendrites tens of microns in width adopting an equivalent dendrite arm width approach. Eventually, the planar solidification front broke down, where after the residual liquid solidified eutectic-like. This material contained γ-phase, Laves phase and, if carbon was dissolved in the liquid, niobium rich carbides formed. Molybdenum and niobium showed strong tendencies to segregate. Their segregation was balanced by inverse segregation of nickel and iron. The chromium concentration remained almost constant in γ in the entire matrix material. Addition of carbon did not cause detectable alterations of the material that experienced planar front solidification. However, it promoted the formation of niobium rich carbides in the material that solidified eutectic-like. Thus, this material differed from that of the pure sample in constitution, and consequently in γ-phase composition. Niobium rich carbides formed prior to Laves phase; in carbon rich volumes only the carbides form. As compared to the pure sample, the sample enriched in iron had decreased global minimal solute concentration in the material that experienced planar front solidification. However, once the concentrations were corrected with respect to the dilution simply caused by the presence of iron, the solidification behaviour in this material was identical to that of the pure sample. The constitution in the material that solidified eutectic-like was γ and Laves phase. As compared to the pure sample, the Laves phase was enriched in iron.
Phase-Field Modeling of Dendritic Solidification in Undercooled Droplets Processed by Electromagnetic Levitation
Authors: Galenko Peter K. , Herlach Dieter M. , Phanikumar G. , Funke O.
Published: March 2009

The results on modeling dendritic solidification from undercooled melts processed by the electromagnetic levitation technique are discussed. In order to model the details of formation of dendritic patterns we use a phase-field model of dendritic growth in a pure undercooled system with convection of the liquid phase. The predictions of the phase-field model are discussed referring to our latest high accuracy measurements of dendrite growth velocities in nickel samples. Special emphasis is given to the growth of dendrites at small and moderate undercoolings. At small undercoolings, the theoretical predictions deviate systematically from experimental data for solidification of nickel dendrites. It is shown that small amounts of impurities and forced convective flow can lead to an enhancement of the velocity of dendritic solidification at small undercoolings.
Microstructures Observed during Directional Solidification along the Univariant Eutectic Reaction in a Ternary Al-Cu-Si Alloy
Authors: De Wilde Jimmy , Froyen Ludo
Published: March 2009

Within the frame of the ESA research program SETA, “Solidification along a Eutectic Path in Ternary Alloys”, experiments have been performed focussing on several distinct subtopics. One of these subtopics is to study coupled growth along the univariant eutectic reaction: L → α + β. In this paper, the influence of the growth velocity v on the morphology of the solid/liquid interface is evaluated in a ternary Al-Cu-Si alloy with a composition close to the univariant eutectic groove L → α(Al) + θ-Αl2Cu. Different structural regions can be identified in terms of the stability of the solid-liquid interface (morphological stability) and the stability of the coupling (competitive growth) during unidirectional solidification as function of the solidification parameters. It is found that two-phase planar growth with a lamellar arrangement can be obtained at a sufficiently low growth rate v. The measured interlamellar spacing follows the Jackson and Hunt relationship λ2v = constant. At a higher growth velocity first a destabilisation of the solid/liquid interface is observed and finally competitive growth is observed revealing primary θ-Al2Cu growing ahead of the eutectic interface. It is assumed that the cellular break-up is a two-step process related to the crystallography of the system. Fitting the different morphologies into one microstructure map, an extension of the coupled zone concept as has been proposed for binary alloys is necessary.
Solid-Solid Phase Transformations in Aluminium Alloys Described by a Multiphase-Field Model
Authors: Kovačević Igor , Šarler Božidar
Published: March 2009

A model for solving isothermal solid-solid phase transformations in multicomponent
aluminium alloys is presented. A multiphase-field model for the dissolutions of various phases in an aluminium matrix during homogenization is presented. Driving forces for phase transformations are calculated using data obtained from the commercial software JMatPro and an aluminium database. An integrated concept of the multiphase-field model with solute diffusion is used. A onedimensional
model for the simultaneous dissolution of the Mg2Si and Si phases in the aluminium
matrix of ternary Al-Mg-Si alloys is introduced. An explicit central finite difference numerical scheme is used for the solution of the time transient phase-field equations and the solute diffusion equations.
Formation of Lead Bearing Surface Layers on Aluminum Alloys by Laser Alloying
Authors: Svéda Mária , Roósz András , Buza Gábor
Published: March 2009

The aim of the present work is to investigate the microstructure of Al-Pb monotectic surface layers generated by a laser surface alloying technique on the surface of an Al-4Cu-1.5Si-0.5Mg alloy. Monotectic alloys are generally used as materials for sliding bearings. Layers of a monotectic alloy generated by laser surface alloying have a potential for superior properties, because the rapid solidification during this process results in fine precipitation structures which can act as solid lubricant. The structure of the Al-Pb monotectic surface layers was observed in the light microscope and the scanning electron microscope. Volume fraction and size distribution of lead particles were determined by quantitative image analysis. Pin-on-disc experiments were carried out to characterize and compare the tribological properties of the Al-Pb monotecitc layers and cast Al-Cu-Si-Mg alloys.
Dependence of Yellow Phosphor on Optical and Electrical Properties of the White Light Emitting Diode Chip
Authors: Son Chang Sik , Chang Ho Jung , Jaekal Kang Hyun , Chang Young Chol , Lee Soo Wohn
Published: March 2009

We prepared the surface mounted white light emitting diode (LED) chips by using
yellow phosphors on the blue LED chip. The optical and electrical properties of prepared white LED chips were investigated. The yellow phosphor mixed with transparent epoxy was coated on the prepared LED chip. The optimum mixing conditions with epoxy and yellow phosphor is obtained at the mixing ration of epoxy: yellow phosphor = 97 : 3 wt %. The maximum luminance and light
emitting efficiency are above 80,000 cd/m2 and 23.2 lm/W, respectively, at the bias voltage of 2.9 V. There was no distinct change in the luminance strength with changing of the yellow phosphor ratios. The flowing current of the white LED chip is about 30 mA at 2.9 V.
Nanosized Titanium Oxynitride and Molybdenum Oxynitride Particles Assembled in Mesoporous Silica MCM-41
Authors: Zheng Shan , Gao Lian
Published: March 2009

Titanium oxynitride and molybdenum oxynitride assembled in the pores of mesoporous materials were achieved by nitriding titania-modified MCM-41 and molybdena-modified MCM-41 at 800°C for 3 hours under flowing NH3 atmosphere. XRD, XPS and N2 adsorption-desorption isotherms were employed to characterize the structure of the composite materials. The results showed that the nanosized TiOxNy and MoOxNy particles were assembled in mesoporous silica
MCM-41 with the restrict mesopores. The hexagonal periodicity of the parent MCM-41 materials was maintained upon assembly at the provided nitridation temperature. The exact formation was TiO0.4N0.8 in MCM-TiOxNy, and MoO1.7N0.57 in MCM-MoOxNy, which were calculated from the data in XPS spectra of Ti 2p and Mo 3d.
Effect of Impurity and Gas Nature on Microstructure of SiC Microtubes in Double Step Reaction Process
Authors: Myoung Sang Won , Kang Jin Ho , Park Seong Hwan , Lee Seoung Soo , Joo Dong Won , Jung Yeon-Gil
Published: March 2009

A novel process in the synthesis of SiC microtubes is proposed, based on modified CVD process. This process was adopted to siliconize the carbon fibers that perform with relatively small surface area, either partially or completely, into the SiC microtubes with large surface area. An oxidic vapor generated from a metal reacts with a carbon solid preform, which leads to a carbide possessing
with a unique morphology. The carbon fiber preforms have been unidirectionally arranged into alumina tube, and then a solid-vapor reaction between carbon fiber preforms and SiO vapor originated from the mixture powder pack of Si and SiO2 has been carried out in restoration atmosphere (argon gas/hydrogen gas = 80/20) at 1450°C. The synthesized SiC.C composites were re-sintered with the modified mixture powder pack of Si, SiO2, Al, and Al2O3 at the same condition,
in which amounts of Al and Al2O3 employed as a impurity have been controlled under 1 wt% with different mole ratios (Al2O3 : Al = 1:1, 2:1, 3:1). Two kinds of SiO and AlO vapors are generated in the second step reaction process, which react with carbon residuals. The quantitative and qualitative properties of the SiC micorotubes were analyzed by using TGA, SEM, and XRD. The inner
morphology of the SiC micorotubes is dependent on the impurity concentration and the gas nature, showing the grains grown with membrane type in the second reaction process because of the impurity.
Process of the One-Dimensional Motion of Small Interstitial-Type Dislocation Loops in Iron
Authors: Arakawa K. , Mori Hirotaro
Published: March 2009

Extensive simulations based on classical molecular dynamics have shown that small
interstitial-type perfect dislocation loops in various metals and alloys have the structure of bundles of crowdions and a loop can easily makes the one-dimensional glide motion due to almost independent motion of crowdions in the loop. However, the experimental knowledge on the motion of loops is not enough. The present study dynamically examined the motion process of loops in pure iron under 1000 keV electron irradiation and thermal annealing by using transmission electron microscopy under which loops could move. Two types of loops were formed by irradiation. Loops of one type possessed the Burgers vector of 1/2<111> and the habit plane of
{011}, and loops of the other type were <001> {001}. Loops of the former type made back-andforth glide motion and expansion towards the direction along their Burgers vectors when they were smaller than about a few-ten nanometers in diameter. This strongly suggests that these small 1/2<111> loops have the structure of the bundle of crowdions. Loops of the latter type only rarely moved less frequently when they were smaller than about the same size. When loops of two types
grew larger than about 50 nm, the characteristics of the motion of loops changed drastically. Dislocation segments of each large loop made long-distance glide independently of their opposite segments, and the habit plane deviated from the original ones. This kind of motion means that selfinterstitial atoms at the central region of such large loops are no longer the crowdions.
Metallurgical and Mechanical Heterogeneity in Weld Materials Considering Multiple Heat Cycles and Phase Transformation
Authors: Toyoda Masao , Mochizuki Masahito , Mikami Yoshiki
Published: March 2009

Joint performances such as tensile strength and hardness in multi-pass welds are induced from both metallurgical and mechanical heterogeneity due to the difference of welding conditions. Hardness distribution in multi-pass weld metal is evaluated with a numerical simulation considering multiple heat cycles and phase transformation. Hardness of multipass weld metal is calculated with
the rule of mixture by using fraction and hardness of each microstructure. In order to calculate fraction of each microstructure, CCT diagram was used. Conventional CCT diagrams of weld metal is not available even for single pass weld metal, thus new diagrams for multi-pass weld metals are created in this study. Modified diagrams for multi-pass weld metals with reheating effect were more dependent on the maximum temperature in reheating than the welding conditions. Hardness
distribution is precisely predicted when the created CCT diagram for the multipass weld metal was used and the detailed calculation of weld thermal cycle is done.
Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System
Authors: Okamoto Nariaki , Fukuda Takashi , Kakeshita Tomoyuki , Takeuchi Tetsuya
Published: March 2009

Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning
plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr
eq. On the other hand, concerning the latter alloy, the maximum of τmag is only
one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr
eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.
Low Temperature Synthesis of TiO2 / SrTiO3 Films on Ti Substrate
Authors: Ueda Masato , Ohzaike Daisaku , Otsuka-Yao-Matsuo Shinya
Published: March 2009

The low temperature synthesis of TiO2 / SrTiO3 films on Ti substrate was examined
focusing on the thickness, the adherence and the surface morphology of the films. The Ti substrate is superior to other ones such as glass, ITO etc from the viewpoint of electrical conductivity and formability. An amorphous-like (amo.) TiO2 film was prepared on the surface of Ti substrate by chemical treatment with H2O2/HCl aqueous solution. The thickness of the amo.TiO2 film increased
almost linearly with the period of the chemical treatment, it had ranges of up to 1.5-2.0µm by the 120min treatment. When the period of chemical treatment was shorter than 60min, which corresponded to the thickness of about 1µm, the uniform and adhesive amo.TiO2 film could be obtained on the substrate. The chemical treatment longer than 60min resulted in inducing cracks in the amo.TiO2 film, they became clear by extending the treatment time. By annealing at 773-873K for
60min in air, the amo.TiO2 transformed mainly to the anatase-type TiO2 showing high crystallinity while a small amount of the rutile-type also appeared. On the other hand, the SrTiO3 film could be obtained on the Ti substrate by annealing the amo.TiO2 coated with Sr(NO3)2 above 773K in Ar. The adherence of the films was also kept after the heat treatments. The synthesis of such films hardly
changed the thickness and the surface morphology. Thus, the TiO2, SrTiO3 films could be easily synthesised at low temperature on the Ti substrate by using the amo.TiO2 film prepared by the chemical treatment. In addition, the formation of TiO2 thin films on the SrTiO3 phase was also discussed.
Stability of the B2-Type Structure of Ti-Ni-Fe and Ti-Ni-Co Shape Memory Alloys
Authors: Choi Mi Seon , Ogawa Jumpei , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

Change in the R-phase transformation behavior with the increase of Fe/Co content in
Ti-(50-x)Ni-xFe and Ti-(50-x)Ni-xCo alloys has been investigated through thermal property measurements and microscope observations in order to clarify the relation among the stability of the B2-type structure, premartensitic phenomena, and the R-phase transformation. It was found that with increasing Fe/Co content, the R-phase transformation behavior approaches a second-order like one.
The transformation product formed very close to the second-order is composed of nanoscale domains, and its Debye temperature is low compared with the R-phase formed by obvious first-order transformation.
Electrochemical Characterization of Ti and Ti Base Alloys under Simulated Body Fluid Environment
Authors: Fujimoto Shinji , Kusu H. , Katsuma S. , Sakamoto Masashi , Tang Y.C.
Published: March 2009

Ti and Ti based alloys are characterised by a continuous electrochemical monitoring
and a rapid straining electrode technique in simulated body fluid environment. Materials examined are Ti, Ti-6Al-7Nb, Ti-6Al-4V and Ti-29Nb-13Ta-4.6Zr. Sterilized specimens were immersed in Hanks solution or Eagle’s minimum essential medium (MEM) solution. Electrode potential and polarization resistance were simultaneously and continuously measured up to 7 days. For all the specimens examined, the corrosion potential reached to a steady state in 2 days for both solutions.
On the other hand, corrosion resistance increased monotonously for the period examined. Tensile specimens were rapidly elongated under potentio-static polarization to evaluate the transient current after exposure of newly-created surface. The anodic current appeared during both elastic and plastic deformation. For Ti alloys, anodic current started to increase gradually during elastic deformation, then increased more rapidly to reveal a maximum when straining was stopped,
then decreased. Pure Ti, on the other hand, revealed the transient current after plastic deformation, but does not show any current increase during elastic deformation. The larger dissolution for a straining was observed as the following order; Ti, Ti-29Nb-13Ta-4.6Zr, Ti-6Al-7Nb, then Ti-6Al-4V.
Novel Method Determining Contact Angle of Liquid Au on Solid Al2O3 Single Crystal (0001) Surface at 1373K
Authors: Lee Joon Ho , Ishimura Hiromichi , Tanaka Toshihiro
Published: March 2009

The contact angle in microscopic size is considered not always to be equal to that in
macroscopic size. Recently, the authors [1] have investigated the contact angle of liquid Au on solid Al2O3 by using a micro-scale wetting method. In that research, however, it was very difficult to get clear information of the contact area. Therefore, the measurements showed considerably large scatter. In this study, a new method with a confocal scanning laser microscope utilizing He-Ne laser beam of
632.8nm and 1.5mW was employed to determine the contact angle in microscopic size. A small piece of gold particle was placed on a solid Al2O3 single crystal substrate which was polished to have the roughness of less than 0.1nm. With flowing a highly purified Ar gas, the sample was heated to 1373K. When the sample was melted to form a liquid drop of spherical shape, the height and width of the gold
drop was measured by the confocal scanning laser microscope. The contact angle was then evaluated from the relationship between the height and width of the drop. [1] By applying this method, the contact angle of liquid Au of 100 µm in radius on solid Al2O3 single crystal of (0001) facet was estimated to be 134 ± 3o. This result is almost the same as that (133~134o) by using the micro-scale wetting method.
Femtosecond Laser Synthesis of the High-Pressure Phase of Iron
Authors: Sano Tomokazu , Sakata Osamu , Ohmura Etsuji , Miyamoto Isamu , Hirose Akio , Kobayashi Kojiro F.
Published: March 2009

The synthesis of the high-pressure ε phase of iron, which has not been observed under a conventional shock compression, was attained using a femtosecond laser. The lower pressure and temperature α phase (bcc) transforms to the γ phase (fcc) at higher temperatures and to the ε phase (hcp) at higher pressures. A shock induced α to ε phase transition in iron is one of the most famous
transitions under high pressure. The induced high-pressure ε phase by a conventional shock loading returns to the α phase and it is not quenched after the shock release because this transition is considered to be diffusionless. Crystalline structures in a recovered iron sample after the femtosecond laser (800 nm, 120 fs, 1014 W/cm2) irradiation were determined using the electron diffraction and the synchrotron X-ray diffraction methods. These results show the existence of the ε
phase and the fcc structure in the recovered iron. The femtosecond laser-driven shock wave may have the potential to synthesis high-pressure phases of other materials that has not been done using the conventional shock wave.
Interfacial Microstructure and Joint Strength of Sn-Ag and Sn-Ag-Cu Lead Free Solders Reflowed on Cu/Ni-P/Au Metallization
Authors: Hirose Akio , Hiramori Tomoyuki , Ito Mototaka , Tanii Yoshiharu , Kobayashi Kojiro F.
Published: March 2009

Sn-3.5Ag (Sn-Ag) and Sn-3.5Ag-0.75Cu (Sn-Ag-Cu) solder balls were reflowed on electroless Ni-P/Au plated Cu pad with varying thickness of Au layer (0 to 500nm). In the Sn-Ag solder joint, a P-rich layer including voids, which resulted from Ni diffusion from the Ni-P plating to form Ni3Sn4 interfacial reaction layer, formed at the interface regardless of Au plating thickness. This
caused the degradation of the joint strength. On the contrary, the Sn-Ag-Cu solder joint had no continuous P-rich layer formed and showed a higher joint strength than the Sn-Ag solder joint in the case of Au plating of 50nm or less. Cu alloying to the solder promote the formation of (Cu, Ni)6Sn5 instead to Ni3Sn4 as the interfacial reaction layer. The (Cu, Ni)6Sn5 reaction layer can suppress the
diffusion of Ni from the N-P plating and thereby inhibit the formation of the P-rich layer. However, in the case of thick Au plating of 250nm or more, a thin P-rich layer formed at the interface even in the Sn-Ag-Cu solder joint and the joint strength was degraded. Au dissolving into the solder from the Au plating during the reflow process may encourage the diffusion of Ni from the Ni-P plating into the solder. As a result, the Sn-Ag-Cu solder joints with 50nm Au coating provided the best joint strength,
although its joint strength considerably degraded after the aging treatment at 423K.
Optimization of the Synthesis of Hydroxyapatite Powders for Biomedical Applications Using Taguchi's Method
Authors: Ranito Cláudia M.S. , Nogueira Carlos A. , Domingues Joaquim , Pedrosa Fátima , Oliveira Fernando A. Costa , Borges João Paulo
Published: March 2009

A conventional method of chemical precipitation was used to produce hydroxyapatite
(HAp) powders, with a molar ratio of Ca/P=1.67, for biomedical applications. The aim of this work was to study the effect of four control factors, namely pH, reaction temperature, reagent concentration and flow rate addition, at three levels, on the Ca/P ratio of the synthesized powders, using the Taguchi design of experiments method. Nine powders were synthesized using Ca(NO3)2ּ4H2O and (NH4)2HPO4 as starting reagents. The Ca/P molar ratio of each powder was
determined by ICP-AES. Data obtained were used in the Taguchi’s design of experiments to optimize the Ca/P molar ratio. Results showed that the pH of the reaction is the main control parameter (74% contribution) affecting the Ca/P molar ratio of the powders. Therefore, attention should be paid to the control of the pH during the synthesis, in order to obtain HAp powders in a reproducible fashion. High pH values (9.5) and reaction temperature at 70 °C favoured the synthesis
of HAp powders with a Ca/P ratio close to the target value of 1.67.
Highly Reactive Alumina Production from Spent Baths
Authors: Ribeiro Catarina , Gonçalves Lucinda , Delmas Francisco
Published: March 2009

Hydrated alumina Al2O3.3H2O was produced from spent alkaline baths resulting from
aluminium transformation industry. Batch and continue laboratory and pilot tests were performed in
order to assess technical viability of producing reactive alumina directly from the baths by a
precipitation/crystallization process and at the same time of recovering and recycling the associated
sodium hydroxide to the extrusion process. The influence of three parameters: time, seed quantity
and dilution were evaluated using a statistical method. It was found that time and dilution are the
factors which have more influence on aluminium precipitation yield, allowing to reach values
greater than 45%. The hydrated aluminas obtained were characterized by granulometric analysis,
scanning electron microscopy and x-ray diffraction. Therefore, apart from minimizing the
environmental impact of the aluminium transformation industry by reducing a waste quantity, it is
obtained a marketable sub-product and recovered a raw material (NaOH), which can be recycled
within the aluminium transformation process.
Selective Laser Melting of Prealloyed High Alloy Steel Powder Beds
Authors: Wright C. Steven , Youseffi M. , Akhtar S.P. , Childs T.H.C. , Hauser C. , Fox P.
Published: March 2009

This paper presents the results of a recent comprehensive investigation of selective laser melting (slm) of prealloyed gas and water atomised M2 and H13 tool steel powders. The objective of the study was to establish the parameters that control the densification of single and multiple layers with the aim of producing high density parts without the need for infiltration. Powders were processed using continuous wave (CW) CO2 and Nd:YAG lasers. Relationships between alloy composition, powder particle size and shape, flowability, microstructure (phases present, their size,
morphology and distribution), track morphology, post scanned density, surface finish and scan conditions (Laser power, spot size and scan speed) are discussed for single track, single layer and multi-layer (up to 25 layers) constructions. Processing with a Nd:YAG laser with powders placed
on substrates rather than on a loose powder bed gave more stable builds than with the CO2 laser. Using the Nd:YAG laser densities up to ~90% relative were possible with H13 powder compared with a maximum of ~70% for M2 in multi-layer builds. Maximum density achieved with CW CO2 processing was only ~60%, irrespective of powder composition. The paper compares the processibility of these materials with stainless steel powders processed to higher densities (up to
99% relative) under similar conditions. The results of the work show that a crucial factor for high density processing is melt pool wettability and this is controlled largely by carbon content; low carbon contents producing better wettability, flatter tracks and higher densities. The significance of this observation for the processing high alloy steels by slm will be discussed.
Electroconductive Ceramic Composites for Cutting Tools
Authors: Almeida Flávia A. , Bóia Helena , Santos Catarina , Monteiro Jorge , Oliveira Filipe J. , Silva Rui F.
Published: March 2009

The addition of titanium nitride (TiN) particles to a Si3N4 matrix reduces the intrinsic electric resistivity of this ceramic allowing it to be machined by EDM in cutting tools manufacturing. Gains can be expected given the cost reduction by the increase of productivity when shaping these hard to machine ceramic materials. Si3N4 ceramic matrix composites (CMC’s) with 0- 30vol.% of TiN sub-micrometric particles were produced by uniaxial hot pressing (HP) and
pressureless sintering (PS). For the PS samples, EDM tests showed that machining of the composites is possible when they contain at least 23vol.% TiN particles what corresponds to a resistivity of 7.5cm. For HP samples at least 30vol.% of TiN is required to get an electroconductive material for EDM machining. This difference is due to the lower temperatures used in the HP process that delay the formation of a conductive network between the TiN particles.
α- to β Transformation on PVDF Films Obtained by Uniaxial Stretch
Authors: Sencadas Vitor , Moreira M. Vitor , Lanceros-Méndez Senentxu , Pouzada António Sergio , Gregório Filho Rinaldo
Published: March 2009

The α to β phase transformation of PVDF through the stretching process at different
temperatures was investigated. The optimum stretching conditions were studied and characterised by infrared spectroscopy and differential scanning calorimetry. The maximum β−phase content was achieved at 80°C and a stretch ratio of 5. Accompanying the phase transformation, a orientation of the polymer chains and a packing of the crystalline structure is observed. The stretch ratio does not
significantly affect the degree of crystallinity.
Mechanochemical Synthesis of Nanocrystalline CeO2: The Effect of Annealing Temperatures on the Particle Size
Authors: Hadi Abdul , Yaacob Iskandar Idris , Ling Lee Seok
Published: March 2009

Cerium dioxide (CeO2) nanoparticles were synthesized by a novel mechanochemical
process. The precursors of Ce2(CO3)3.xH2O and NaOH were mixed at a weight ratio of 4 to 1. The
mixtures were milled using a planetary ball mill with ball to powder ratio of 10:1. The products
were then characterized using a battery of characterization methods, including X-ray diffraction
(XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and gas
adsorption-desorption measurement. The as-prepared particles were largely amorphous with an
average specific surface area of about 119.94 m2/g. Nanocrystalline CeO2 with crystallite size of
4.5 nm was obtained when the sample was annealed in air at 350 oC. The heat treatment results
showed that the crystallinity of nanocrystalline CeO2 increased with increasing annealing
temperature.