bluuebunny/crossref_metadata_2025 huggingface dataset:
Springback Behavior of an Invar Sheet and Its Perforated Form
Authors: Lee Yi Che , Chen Fuh Kuo
Published: March 2009

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under
bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the
experimental data and the predicted values confirms the validity of the proposed theoretical model as well.
The Optimal Cutting-Parameter Design of Heavy Cutting in Side Milling for SUS304 Stainless Steel
Authors: Chang Ching Kao , Lu H.S.
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.
Finite Element Analysis of Room Temperature Nanoimprint Lithography Process with Rate Dependent Plasticity
Authors: Song Jung Han , Huh Hoon , Kim Seung Ho , Hahn H.Thomas
Published: March 2009

Nanoimprint lithography (NIL) process at the room temperature has been proposed newly to achieve the shape accuracy and to overcome the sticking problem induced in conventional NIL processes. Success of the room temperature NIL relies on the complete understanding of the mechanical behavior of the polymer. Since a conventional NIL process has to heat a polymer above the glass transition temperature to deform the physical shape of the polymer with a mold pattern,
visco-elastic properties of the polymer have major effect on the NIL process. The rate dependent behavior of the polymer is also important in the room temperature NIL process because a mold is rapidly pressed onto the polymer while there has been no study on the rate-dependent NIL process. In this paper, finite element analysis of the room temperature NIL process is performed with the consideration of the strain-rate dependent behavior of the polymer. The analyses with the variation of
the imprinting speed and the imprinting pattern are carried out in order to investigate the effect of the process parameters on the room temperature NIL process. The analysis results show that the deformed shape and the imprinting force are diversified with the variation of the imprinting speed due to the dynamic behavior of the polymer with the rate dependent plasticity model. The results provide a
guideline to determine the process conditions in the room temperature NIL process.
The Effect of Spindle Speed Variation on Chatter Suppression in Rotating-Tool Machining
Authors: Li Chen Jung , Ulsoy A.G. , Endres W.J.
Published: March 2009

Spindle speed variation (SSV) is one of a number of promising strategies to suppress chatter. Most previous research on SSV stability analysis for nonintermittent machining processes has focused on stationary-bar boring or turning. However, nonintermittent rotating-tool machining is also a common process. This paper investigates the effect of SSV in nonintermittent rotating-tool machining, using rotating-bar boring as an example. This paper takes advantage of the rotating-frame approach and the resulting constant delay in the angle domain to investigate the SSV effect on system stability for rotating-bar boring. The results show that the SSV effect on rotating-bar boring flattens the stability lobes and lifts the tangential stability limits.
Effects of Human Factors on Performance of Advanced Manufacturing Technology: An Empirical Examination
Authors: Song Jin Bo , Dai D.S. , Wang D.B. , Song Y.Q.
Published: March 2009

To be successful in this globally competitive and rapidly changing situation, organizational changes, which must be consistent with the implementation of manufacturing technology, are required. This study proposes that human factors in the organization have improved the implementation effects of AMT. Based on a brief review of relevant literatures, three categories including twelve indicators are concluded as valid and reliable measures of the implementation
effects of AMT. Using the result from a survey of 87 equipment manufacturing firms in the northeast of China, a stepwise regression analysis is conducted to investigate the diversity influence on AMT implementation by human factors. The results show that training, equitable reward and team cooperation have positive effect on operational performance; equitable reward, empowerment and
team cooperation are positively correlated with organizational and managerial performance; the relationship between team cooperation and competitive performance is significant and positive.
Automatic Inspection of Pipe Using Non-Contact Guided-Wave Technique with Enhanced Mode-Selectivity
Authors: Jhang Kyung Young , Kim Hyun Mook
Published: March 2009

Ultrasonic guided wave has been widely used for the pipe inspection. The conventional method is to use piezoelectric transducers that should be contacted to the target surface. However, in order to automatically inspect pipes in the manufacturing stage, non-contact inspections are strongly required. In this paper, we propose a new non-contact method for the automation of pipe inspection,
which generates the ultrasonic guided wave by laser and receives by air-coupled transducer. Also we have developed a rotational canning system to show the inspection result as a 2-D image, which makes the operator find out defects easily. Then, in practical applications of guided wave techniques, it is preferred to generate and detect a single or less dispersive mode. So this paper considers the
enhancement of mode-selectivity, where a laser beam illuminated through arrayed line slits is used as the transmitter and the air-coupled transducer is used as the receiver. The line arrayed laser illumination is a wavelength matching technique that can generate only a few modes. The air-coupled transducer detects the leaky wave of the propagated guided wave, and by tuning its detection angle we
can detect the selected single mode. This method can generate and receive the guided wave of a specific mode, which makes the interpretation of received signal clearer and resultantly improves the accuracy of inspection. The proposed method was applied to the stainless pipe specimen with artificial defects and its inspection performance was verified. The experimental results showed that the fundamental axial-longitudinal mode was dominantly generated and received, and the location
and the size of pipe defects could be displayed well in the 2 dimensional scanning images in real time.
Study on Eccentricity and Minimum Geometrical Center Distance of the Eccentric Involute Gears Transmission
Authors: Han Ji Guang , Wang Gui Cheng
Published: March 2009

The traditional design and analysis method for the eccentric involutes gears transmission has model error. Some important parameters, such as minimum geometrical center distance and eccentricity, are not calculated accurately. The differential equation of eccentric involute gears transmission is established on account of the geometrical relationship of eccentric involute gears
transmission. A calculating method of the geometrical center distance and eccentricity are derived. The relationship between the minimum geometrical center distance or maximum transmission ratio and initial meshing angle and eccentricity are analyzed. The minimum geometrical center distance and eccentricity are fitted by polynomial. The analysis and design can be completed fast and accurately by using polynomial fitting formals, so the process of analysis and design are simplified.
Grain Boundary Influence on the Electrical Properties of Tellurium Microstructure Ingots and Nanocluster Crystals
Authors: Berezovets V.A. , Farbshtein I.I. , Parfeniev R.V. , Yakimov Sergei V. , Nizhankovskii V.I.
Published: March 2009

The high sensitivity of the low temperature electrical properties of p-type pure tellurium (Te) to impurities, structural boundaries, point defects and dislocations allows to investigate the structural imperfection profiles in crystals grown under different conditions. Our interest was focused on studying the influence of grain boundaries on the electrical properties of the samples that were remelted and directionally solidified in space (µg) without a seed (W-µg), in comparison
with the sample grown under the normal earth conditions (1g0) and a nanocluster sample obtained by filling with melted Te of dielectric opal matrix voids (Opal sample). The W-µg ingot of Te was prepared in the "Crystallizator" furnace under microgravity conditions aboard the "Mir" space station [1]. The concentration variation of electrically active defects and neutral defects along the samples
were studied by galvanomagnetic methods (Hall effect and electrical resistivity) in a wide temperature range from 0.4 to 300 K. In these measurements, the following effects caused by the micro- and nano- crystalline structure were found: low hole mobility, high concentration of neutral defects, and anomalous positive magnetoresistance in low magnetic fields at low temperatures. Besides, the specific resistivity of the space sample was found to oscillate (up to 20%) along the
length which can be correlated with the presence of a few contact points of the melt with the ampoule wall. This ingot was formed as a result of rapid homogeneous spontaneous solidification, accompanied by forming a micro-block structure.
The appearance of the anomalous positive magnetoresistance was observed in the micro-block W- sample and the nanocluster Opal sample. It is a consequence of intensive hole scattering at the grain boundaries which leads to an increase of the intervalley transition probability and to a change of the spin sign of holes in a low symmetry Te crystal. According to the weak localization theory [2], the spin variation during the scattering results in a positive magnetoresistance of the
sample in low magnetic fields, in contrast to bulk Te crystals.
Investigation of Phenomena Taking Place in LASER Surface Alloying Steels of WC-Co
Authors: Bitay Enikő , Roósz András
Published: March 2009

The laser surface-treatment methods have been quickly developed by appearing of lasers with high power beam and can increase the hardness, of the surface. A very hard, wear-resisting layer can be produced by the dispersing of ceramic grains. The essence of the technology is, that such a material (compound-phase, e.g.: metal-oxide, carbide, nitride, etc.) is added to the surface layer melted by laser, which does not solve or solves only partly in the metal-melt. This work studies the effect of the different technological parameter (such as, power of the laserbeam, motion speed, amount of the ceramic particles etc.) on the different microstructure accrued
during the laser surface alloying. The desired microstructure has homogeneous carbide distribution in the matrix. But it is embarrassed by several conditions. The aim of this present work is to find out the reasons for the inhomogeneous ceramic particle distribution inside the matrix and to discover these embarrassing conditions.
Constitutive Equation for Thermal Strain in the Mushy Zone during Solidification of Aluminium Alloys
Authors: Stangeland Aage , Mo Asbjørn , Eskin Dmitry G.
Published: March 2009

A constitutive equation for thermal strain in the mushy zone has recently been established [1]. The parameters in this constitutive relation are in the present study determined for the commercial alloys A356, AA2024, AA6061 and AA7075 in addition to an Al-4 wt% Cu alloy by combining experimentally measured contraction of a cast sample with thermomechanical simulations. The constitutive equation for thermal strain in the mushy zone reflects that there is no thermal strain in the solid part of the mushy zone at low solid fractions and that the thermal strain in the mushy zone approaches thermal contraction in fully solid as the solid fraction increases towards one. Experiments were performed at cooling rates in the range from 2 to 5.5 °C/s. The solid fractions when the tested alloys start to contract, gsth, are in the range from 0.63 to 0.94. Grain refinement increases gsthfor all the tested alloys.
Modelling of the Mushy Zone Permeability for Solidification of Binary Alloys
Authors: Furmanski Piotr , Banaszek Jerzy
Published: March 2009

An ensemble averaging technique is used to obtain both macroscopic equations of transport phenomena in a two-phase region and new models of permeability and thermal conductivity of the columnar mushy zone through the analysis of most likely configurations of the local microstructure. The obtained formulae are incorporated into a FEM computer code for the macroscopic analysis of binary mixture solidification with convection. The influence of various models of mushy zone permeability on temporal shapes of the two-phase region as well as on velocity and temperature fields is studied for a test case of solidification of a dilute solution of ammonium chloride and water in a square cavity. For this case, relatively small differences in liquid flow patterns and temporal shapes of the two-phase region are observed for significantly different models of mushy zone permeability.
The Effect of Fluid Convection on Microstructures of Directionally Solidified Castings
Authors: Lei Tien Shou , Chang Wen Shiung , Dong Shyen Yang
Published: March 2009

Fluid convection during solidification of castings will influence the final structures of the castings. A vertical cylindrical casting set-up has been designed to provide two zones of solidification simultaneously with two moving fronts directionally upward and directionally downward, respectively. This two zone directional solidification casting was composed of a cylindrical Furan sand mold with a water chilled center hole block at the center of the casting. Experimentally it was observed that the cooling rates at different locations of the downward zone were much more even than those of the upward one and this is considered to be the result of a more even temperature distribution along the downward front moving zone due to stronger fluid convection. Fluid convection tends to mix up the liquid and results in a more even temperature distribution and a lower degree of segregation of the element molybdenum which has a strong tendency to segregate to the carbide in ductile iron. The characteristics of the matrix microstructure and the growing direction of carbide of this directionally solidified ductile iron has been investigated with SEM and EBSD techniques.
Thermal Analysis of the Mg-Al Alloys
Authors: Medved Jožef , Mrvar Primož
Published: March 2009

Multi-crystalline silicon ingot casting using directional crystallisation is the most costeffective technique for the production of Si for the photovoltaic industry. Non-uniform cooling conditions and a non-planarity of the solidification front result, however, in the build-up of stresses and viscoplastic deformation. Known defects, such as dislocations and residual stresses, can then occur and reduce the quality of the produced material. Numerical simulation, combined with experimental
investigation, is therefore a key tool for understanding the crystallisation process, and optimizing it. The purpose of the present work is to present an experimental furnace for directional crystallisation of silicon, and its analysis by means of numerical simulation. The complete casting procedure, i.e., including both the crystallisation phase and the subsequent ingot cooling, is simulated. The thermal
field has been computed by a CFD tool, taking into account important phenomena such as radiation and convection in the melt. The transient thermal field is used as input for a thermo-elasto-viscoplastic model for the analysis of stress build-up and viscoplastic deformation during the process. Numerical analysis is employed to identify process phases where further optimisation is needed in order to reduce
generated defects.
In Situ and Real Time Investigation of Directional Solidification of Al - Ni Alloys by Synchrotron Imaging
Authors: Reinhart Guillaume , Nguyen-Thi Henri , Gastaldi J. , Billia Bernard , Mangelinck-Noël Nathalie , Schenk Thomas , Härtwig J. , Baruchel J.
Published: March 2009

Solidification is a dynamic phenomena and, as a consequence, it is of major interest to be able to investigate this process by in situ and real time observation. With synchrotron sources, this can be achieved by applying X-ray Imaging techniques (Radiography and Topography). Hence it is possible to follow the dynamical selection of solidification pattern on metallic alloys and to observe strain effects during growth process. In this paper, we present results obtained by using separately the two imaging techniques for the study of the microstructure formation during Al – Ni alloys solidification.
Multiscale Approach to Texture-Microstructure Coupling
Authors: Penelle Richard , Baudin Thierry
Published: March 2009

Materials exhibit microstructures and textures that influence their use and properties. Xray and neutron diffraction allow characterization of the bulk texture, whereas Electron Backscattered Diffraction (EBSD) permits determination of the local texture. In many cases Transmission Electron Microscopy (TEM) remains necessary to characterize the substructure and the local texture for highly deformed materials. Depending on the scale considered, all these complementary techniques permit the coupling of texture and microstructure so that it becomes possible to control microstructure and its evolution during a processing route. Some examples in titanium aluminides, (α + β) titanium alloys and an Fe-Ni alloy will illustrate this challenge.
Synthesis of Al2O3-Ni3Al Cermets by Room-Temperature Ball Milling of Al, Ni and Al2O3 Mixtures
Authors: Rocha-Rangel Enrique , Moreno-Guerrero M.S. , Velásquez-Naranjo A. , Refugio-García Elizabeth
Published: March 2009

The synthesis of Al2O3-Ni3Al cermets with interpenetrating networks has been performed via a pressureless reactive sintering process. The synthesis has been induced by means of a solidstate reaction of Al + Ni + Al2O3 powders under intensive ball milling. The mixtures have been heat treated in an inert atmosphere (N2) in order to control the exothermic reaction between Ni and Al,
with special care at temperatures near the melting point of Al. Dense and homogeneous microstructures have been obtained, composed by a matrix of Al2O3 reinforced with a Ni3Al intermetallic. Thermodynamic calculations indicate that such a cermet can be fabricated by in situ reaction synthesis. This suggests that a pressureless reaction sintering process may be a general route to synthesizing cermets with the prospect for the production of cermets with interpenetrating
networks.
Use of Newton Thermal Analysis for the Prediction of the Amount of Microconstituents Formed during Solidification
Authors: Cruz H. , López L. , Campillo B. , González-Rivera Carlos
Published: March 2009

This work explores the feasibility of using the Newton Thermal Analysis method (NTA) as an alternative technique for quantitative determination of the relative volume fractions of the microconstituents formed during solidification of three hypereutectic Pb-Sn alloys. The results suggest that NTA has a good potential as a quantitative microstructure analysis tool. However, it is required to further improve the method in order to match the microstructure predictions with the
experimental measurements obtained by quantitative metallography.
The Electrochemical Properties of Poly(acrylonitrile) Polymer Electrolyte for Li/S Battery
Authors: Ryu Ho Suk , Choi Jae Won , Ahn Jou Hyeon , Cho Gyu Bong , Ahn Hyo Jun
Published: March 2009

The lithium ionic conductivity of Poly (acrylonitrile) (PAN) gel polymer electrolyte with PC/EC was found to be about 1.3 x 10-3S/cm at room temperature. The discharge curve of Li/ PAN (PC+EC)/S battery showed only one plateau region, which is different from that using PVdF(TEGDME) gel polymer electrolyte. Also, the first discharge capacity was 556mAh/g-sulfur in Li/S battery using PAN (PC+EC) gel electrolyte at room temperature.
The Effect of Boron on the Sliding Wear Behavior of Iron-Based Hardfacing Alloys for Nuclear Power Plants Valves
Authors: Yoo Jeng Wan , Lee Kwon Yeong , Kim Ji Hui , Kim Ki Soo , Kim Seon Jin
Published: March 2009

A new iron-based wear resistance alloy was developed to replace the Co-containing
Stellite 6 alloys in nuclear power industry. The effect of B addition on the wear resistance was investigated. Sliding wear tests of Fe-Cr-C-Si-xB (x = 0.0, 0.3, 0.6, 1.0 and 2.0 wt%) alloys were performed in air at the room temperature under a contact stress of 103 MPa. Low-boron alloys containing less than 0.6 wt% boron showed an excellent wear resistance than any other tested alloys. The improvement was associated with the matrix hardening by promotion of the γ→α′straininduced
martensitic transformation occurring during the wear test. However, the alloys containing more than 1.0 wt% boron showed slightly increased wear loss compared to the low-boron alloys because of the absence of the strain-induced martensitic transformation and the presence of the brittle FeB particles, aiding crack initiation.
Effect of Electron Irradiation on Nanocrystallization of Fe-Nd-B Amorphous Alloys
Authors: Nino Akihiro , Nagase Takeshi , Umakoshi Yukichi
Published: March 2009

Formation of a nanocrystalline structure through rapid solidification, thermal
crystallization and electron irradiation induced crystallization was investigated in Fe-Nd-B alloys. A nanocrystalline structure was obtained by rapid quenching of the melt in a Fe86Nd9B5 alloy, while an amorphous single phase was formed in a Fe77Nd4.5B18.5 alloy. In the latter alloy, a nanocrystalline structure was obtained by thermal crystallization and electron irradiation induced crystallization of
the amorphous phase. The average grain size of the precipitate obtained by irradiation at 298 K was about 8 nm, which is much smaller than that obtained during thermal crystallization. Results indicate that electron irradiation is effective for obtaining a novel nanocrystalline structure in Fe-Nd-B alloys.
Tailored Electrochemical Surface Modification of Semiconductors
Authors: Schmuki Patrik
Published: March 2009

The paper gives an overview of recent research activities that explore new pathways to achieve selective structurization of semiconductor surfaces by electrochemical deposition or dissolution techniques. Of a particular emphasis are pathways that are based on a two step procedure: First, locally a semiconductor surface is selectively activated (or de-activated) using techniques with
a high lateral resolution (focussed ion electron beam, or AFM). In a second step, an electrochemical reaction (dissolution or material deposition) is selectively carried out at sensitized surface locations. Different examples of this strategy are given including selective suppression of a surface by damage
induced amorphization. Additionally, smart structuring approaches involving self-organization of deposition or dissolution processes are shortly discussed.
Application of Large Magnetocaloric Effects in Itinerant-Electron Metamagnets to Cooling Systems
Authors: Fukamichi Kazuaki , Fujita A. , Fujieda S.
Published: March 2009

The La(FexSi1-x)13 compounds exhibit large magnetocaloric effects (MCEs) due to the itinerant-electron metamagnetic (IEM) transition. By hydrogen absorption, the Curie temperature TC increases up to room temperature with retaining the IEM transition. The La(Fe0.90Si0.10)13H1.1 compound indicates a large isothermal magnetic entropy change of ∆Sm = - 28 J/kg K at 287 K in the magnetic field change from 0 to 2 T (∆B = 2 T). In addition, the MCEs are enhanced by partial substitution of Ce for La. The value of TC for La(FexSi1-x)13 is decreased by partial substitution of Mn for Fe, keeping excellent MCEs.
Consequently, the La(FexSi1-x)13 and their modified compounds are promising as magnetic refrigerants working at a wide range of temperature covering room temperature.
Behaviors of Nonequilibrium Carriers in Er, O-Codoped GaAs for 1.5μm Light-Emitting Devices with Extremely Stable Wavelength
Authors: Fujiwara Yasufumi , Koizumi Atsushi , Nakamura Kazuhiko , Suzuki Masato , Takeda Yoshikazu , Tonouchi Masayoshi
Published: March 2009

We have fabricated GaInP/Er,O-codoped GaAs (GaAs:Er,O)/GaInP double heterostructure (DH) light-emitting diodes (LEDs) and successfully observed 1.5 µm electroluminescence (EL) due to an Er-2O center under forward bias at room temperature. Er excitation cross section by current injection decreased with increasing GaAs:Er,O active layer thickness, implying reduced diffusion
length of injected carriers in the active layer. Carrier dynamics in GaAs:Er,O have also been investigated by means of a pump and probe reflection technique. Time-resolved reflectivity of GaAs:Er,O exhibited a characteristic dip after a steep decrease to negative in less than 10 ps. The analysis of the characteristic dip revealed short lifetime in range of ps for photoexcited carriers. The
extremely short lifetime is quite coincident with the reduced diffusion length of injected carriers, and suggests that a trap induced by Er and O codoping would play an important role in dynamics of nonequilibrium carriers in GaAs:Er,O.
Magnetism of Ultrathin Fe Films in the Vicinity of Transition from Ferromagnetism to Superparamagnetism
Authors: Shiratsuchi Yu , Endo Yasushi , Yamamoto Masahiko
Published: March 2009

We have investigated the magnetism of ultrathin Fe films grown on the inclined
Al2O3(0001), especially, in the vicinity of ferromagnetic-superparamagnetic transition. In the transition region, the magnetic state of Fe films is the coexistence of ferromagnetism and superparamagnetism. The ratio of the components in ferromagnetic and superparamagnetic state is dependent on the growth temperature. For Fe grown on the flat substrate without the inclination,
as the growth temperature increases, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. On the presence of substrate inclination, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. decreases monotonically with increasing growth temperature. We investigated the dominant factor
of the complex magnetic state, and clarified that the complex magnetic state is dominated by the change of the film structure and the effective magnetic anisotropy energy.
Magnetization Chirality of Ni-Fe and Ni-Fe/Mn-Ir Asymmetric Ring Dots for High-Density Memory Cells
Authors: Sasaki Isao , Nakatani Ryoichi , Yoshida Tetsuo , Otaki Keiichi , Endo Yasushi , Kawamura Yoshio , Yamamoto Masahiko , Takenaga Takashi , Aya Sunao , Kuroiwa Takeharu , Beysen Sadeh , Kobayashi Hiroshi
Published: March 2009

The magnetic configurations of Ni-20at%Fe/Hf and Ta/Ni-20at%Fe/Mn-28at%Ir/
Ni-20at%Fe/Ta asymmetric ring dots have been studied. Recently, we proposed that asymmetric ring structures are suitable for magnetic memory cells and then demonstrated that asymmetric structures can control the chirality of the vortical magnetization with in-plane fields. The investigation of the Ni-20at%Fe(20 nm)/Hf(5 nm) asymmetric ring dots for free layers in magnetic memory cells
demonstrated that switching fields cause a transition from the vortex state to the onion state that increases as the ring width decreases from 410 nm to 210 nm since a narrow ring has a higher demagnetizing field than that of a wide ring during the transition. The investigation of the Ta(3 nm)/Ni-20at%Fe(15 nm)/Mn-28at%Ir(10 nm)/Ni-20at%Fe(3 nm)/Ta(5 nm) asymmetric ring dots for
the pinned layers in magnetic memory cells demonstrated that the chirality of the vortical magnetization is pinned regardless of the magnetic field direction.
Magnetic Phase Diagram in Layered Perovskite Manganite La2-2xSr1+2xMn2O7 (0.313≤x≤0.350)
Authors: Murata Takeshi , Terai Tomoyuki , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

We have measured the magnetization as a function of temperature and magnetic field in layered perovskite manganites of La2-2xSr1+2xMn2O7 single crystals (x=0.313, 0.315, 0.320, 0.350) in order to know their magnetic structures. All the present manganites exhibit magnetic transitions from ferromagnetic to paramagnetic at 76K, 107K, 120K and 125K for x=0.313, 0.315, 0.320 and 0.350, respectively. For x=0.350 and 0.320, the magnetic structure is a planar ferromagnetism whose easy
axis is in the ab-plane at all temperatures below the Curie temperature. On the other hand, for x=0.315 and 0.313, the magnetic structure is an uniaxial ferromagnetism whose easy axis is along the c-axis below 85K and 66K, respectively, and a planar ferromagnetism above the temperature. From the results described above, we made the detailed magnetic phase diagram of layered perovskite manganite La2-2xSr1+2xMn2O7 (0.313≤x≤0.350).
Influence of Magnetic Field Direction and Temperature on Rearrangement of Martensite Variants in Fe-31.2at.%Pd
Authors: Sakamoto Tatsuaki , Fukuda Takashi , Kakeshita Tomoyuki
Published: March 2009

We have measured temperature dependence of the uniaxial magnetocrystalline
anisotropy constant Ku and the shear stress τr eq required for the twinning plane movement of an Fe-31.2Pd alloy in order to explain the field orientation dependence of rearrangement of martensite variants (RMV) of this alloy in the field-cooling process. Under the [001]P field (P represents parent phase), the RMV occurs perfectly at the temperatures where the measurement was performed; in
this case, the magnetic shear stress acting across the twinning plane τmag, which is evaluated from Ku, becomes nearly twice as large as τr eq. On the other hand, under the [011]P field, the RMV occurs partially at all the measuring temperatures; in this case the maximum of τmag is nearly the same as τr eq. It is successful to evaluate the following relation quantitatively; τmag> τr eq is satisfied when RMV occurs under magnetic field.
Design of Automatic Matching System for Very High Frequency Plasma-Enhanced Processes
Authors: Yoshizako Yuji , Matsuno Daisuke
Published: March 2009

Since it can change electron energy distribution functions, very high frequency (VHF) plasma has gained significant attention as a promising new class of plasma. We demonstrate an automatic matching system for VHF plasma, that works in very wide ranges. A matching system was prepared using conventional variable capacitors. Reflection coefficient at the input of the matching circuits was measured with a directional coupler. A new calculation method for automatic matching
based on numerical models for the circuit was developed, and the performance of the automatic matching system was evaluated using a load emulator. These results revealed that the system has an automatic matching capability for the entire range of the covering load area.
Role of Osteoclast in Preferential Alignment of Biological Apatite (BAp) in Long Bones
Authors: Lee Jee Wook , Nakano Takayoshi , Toyosawa Satoru , Ijuhin Naokuni , Tabata Yasuhiko , Yamamoto Masaya , Umakoshi Yukichi
Published: March 2009

Absorption and formation of hard tissues are repeated in vivo by the activity of osteoclast and osteoblast, respectively. The preferential alignment of BAp or collagen fibril is thought to be closely related to the activity of the bone cells. In this study, changes in bone mineral density (BMD) and preferential alignment of biological apatite (BAp) were examined focusing on the role of
osteoblast using the model of osteopetrotic (op/op) mice in which osteoblast activity was normal but the expression of osteoclast was reduced. Osteopetrotic (op/op) mice and their normal littermates aged 5, 12 and 24 weeks were analyzed. The BMD and BAp texture of femoral diaphysis were
measured using peripheral quantitative computed tomography (pQCT) and a microbeam X-ray diffractometer system with a 50 µmφ diameter beam spot respectively. The decrease in osteoclast expression induced both the reduction of the skeletal system and calcification of the medullary cavity, which are typical features of osteopetrosis. As a result, the shape, BMD and preferential BAp alignment of the femur in the op/op mice were remarkably different from
those in the control group. At the center of the femoral diaphysis, BMD in the cortical area showed no significant difference between the two groups, but preferential alignment of the BAp c-axis in the op/op mice group had a lower value than that in the control group. This suggests that the decrease in the number of osteoclasts
suppresses normal remodeling, resulting in a decrease in bone quality, especially the preferential alignment of the BAp c-axis.
Study of Microstructure in Surface-Melted Region of Ni-Base Single Crystal Superalloy CMSX-4
Authors: Fujita Yoshihiro , Saida Kazuyoshi , Nishimoto Kazutoshi
Published: March 2009

This work investigated microstructure in the surface-melted region of Ni-base single
crystal superalloy CMSX-4 by using a diode laser beam as a heating source. Such processing parameters as laser power and scanning speed in laser surface melting were varied while defocusing distance and shielding gas (Ar) flow rates were fixed. Specimen surfaces were arranged parallel to the (001) of base alloy. The microstructure in the melted region was analyzed by optical microscopy
and SEM. Crystal orientation of the melted region was analyzed using electron backscattered pattern analysis. The microstructure was remarkably changed when the heat input of surface melting was varied. The surface-melted region was found to solidify into a single crystal with directional dendrites that grew along the [001] directions under low heat input conditions. The surface-melted region was also a single crystal with disoriented dendrites that grew along the [100] or [010] directions under medium heat input conditions. In contrast, the melted region consisted of
poly crystals with stray crystals under high heat input conditions. Such tendencies were also observed in the melted region with gas tungsten arc. These results demonstrate that the surface-melted region can solidify into a single crystal under conditions in which larger temperature gradient and higher solidification rates can be achieved.
Measurement and Analysis of Vibration Damping Capacity of Lotus-Type Porous Magnesium
Authors: Xie Zhen Kai , Hyun Soong Keun , Okuda Yosiyuki , Nakajima Hideo
Published: March 2009

Lotus-type porous magnesium was fabricated by unidirectional solidification of the melt dissolving hydrogen in a high-pressure mixture gas of hydrogen and argon. The damping constant of porous magnesium with various porosities was measured by the hanging excitation method. The damping constant was defined as α=log (xn/xn+1)/T, where xn and xn+1 are the successive amplitude values of the damping wave, and T is the damping time. The frequency-amplitude dependence
curve was obtained by Fast Fourier Transform analysis. The damping time of the lotus-type porous magnesium was observed to be shortened greatly compared with non-porous metals and porous copper. Moreover, the damping constant of the lotus-type porous magnesium was calculated by the damping amplitude.
Influence of Resin Viscosity and Filler Volume on Self-Organized Micro Interconnection
Authors: Yasuda Kiyokazu , Ohta Koushi , Fujimoto Kozo
Published: March 2009

The novel selective interconnection using the resin containing low-melting-point-alloy
fillers was developed as a high density assembly method of a low-temperature and highly reliable electronic interconnection. By means of the coalescence of fillers and wetting onto the terminal material due to the Laplace pressure of the fillers, self-organization onto the terminals was formed. The influence of the filler volume ratio and resin viscosity on the self-organized interconnecting was investigated by the numerical analysis with a multi-filler dispersion model corresponding to a real
process, and was evaluated by using the normalized parameter (self-organization ratio). We clarified the existence of the optimal value of the filler volume ratio. The rate controlling factor transferred from the filler volume to the inflow velocity by the increase of the viscosity.
Superplastic Deformation and Thermal Crystallization Behavior of Supercooled Liquid in Zr-Ni Based Metallic Glass
Authors: Nagase Takeshi , Nakamura Mitsuo , Umakoshi Yukichi
Published: March 2009

Superplastic viscous deformation and thermal crystallization behavior of supercooled liquid in Zr60.0Al15.0Ni25.0 metallic glass were investigated. The temperature interval of the supercooled liquid region (∆Tx) was 83 K. The supercooled liquid showed significant viscous plasticity, resulting
in large elongation and high strain rate deformation. The stress-strain behavior can be classified into three types: stress overshoot, stable viscous flow with constant flow stress and strain hardening. The strain hardening is due to the precipitation of Zr6Al2Ni crystalline phase with ellipsoidal morphology. Superplastic viscous deformation behavior is very sensitive to thermal crystallization as well as to
deformation temperature and strain rate.
Temperature and Orientation Dependence of Fracture Behavior of Directionally Solidified Duplex-Phase Crystals Composed of Ni3X-Type Intermetallic Compounds
Authors: Hagihara Koji , Yokotani Naoyuki , Umakoshi Yukichi
Published: March 2009

Fracture behaviors of three directionally solidified (DS) duplex-phase alloys composed of Ni3Nb(D0a)/Ni3Al(L12), Ni6TaAl(D024)/Ni3Al(L12) and Ni3Ti(D024)/Ni3Si(L12) phases, respectively were investigated by three-point bending tests, focusing on temperature and orientation dependence.
The temperature-toughness relation showed dissimilar curves depending on alloy. The increasing rate of fracture toughness was the highest in the Ni3Al/Ni3Nb alloy with fine lamellar structure and was the lowest in the Ni3Al/Ni6TaAl alloy with rod-like precipitates. The controlling mechanism for the temperature dependence of fracture behavior of Ni3Al/Ni3Nb alloys was discussed.
Fine-Grained Structure Formation in 7475 Al Alloy during Hot Multidirectional Forging
Authors: Goloborodko Alexandre , Sitdikov Oleg , Miura Hiromi , Sakai Taku
Published: March 2009

Effect of strain rate on grain refinement was studied in multidirectional forging
(MDF) of a coarse-grained 7475 Al alloy at 490oC under strain rates of 3 × 10-4 s-1 and 3 × 10-2 s-1. At a strain rate of 3 × 10-4 s-1, the stress – strain ( σ - ε) behavior shows significant work softening just after yielding and a steady-state flow at higher strains. The structural changes are characterized by development of deformation bands at early stages of deformation, followed by formation of a
fine grain structure in high strain in the whole material. The volume fraction of new grains increases with strain and approaches a value of about 0.85 over a strain of 3. At a higher strain rate of 3 × 10-2 s-1, in contrast, a steady-state flow following small flow softening appears at a relatively low strain. New grains are formed during steady state flow along original grain boundaries and the volume
fraction reaches below 0.2 even in high strain. The occurrence conditions and the mechanisms of grain refinement are discussed in detail.
Tensile Deformation Behaviors of Ultrafine Grained Al-Fe-Si Alloy Sheets
Authors: Kim Hyoung Wook , Kang Suk Bong , Tsuji Nobuhiro , Minamino Yoritoshi
Published: March 2009

Ultra-fine grained AA8011 alloy sheets manufactured by the accumulative roll-bonding (ARB) process exhibited unique tensile deformation behavior. Tensile strength of the ARB processed AA8011 sheets increased up to three cycles, but then showed nearly the same value after three cycles. Meanwhile, the total elongation grew significantly with an increasing nember of ARB cycles. It was
found that the strain-rate sensitivities (m) of the AA8011 sheets increased up to 0.047 by the ARB process. A large number of high-angle boundaries were introduced by the ARB process and the fraction of high-angle boundaries reached 70% after eight ARB cycles. In this paper, we discusse the increase in total elongation on the basis of strain-rate sensitive deformation of the material, which is
also correlated with dynamic recovery.
Microstructure, Properties and Biocompatibility of the Nitrided Ti-6Al-4V Alloy for Medical Application
Authors: Czyrska-Filemonowicz A. , Buffat P.A. , Czarnowska E. , Wierzchoń Tadeusz
Published: March 2009

Investigation of the microstructure, properties and biocompatibility of the Ti-6Al-4V alloy nitrided under glow discharge was performed. The microstructural analyses were carried out using light microscopy, X-ray diffraction, analytical scanning and transmission electron microscopy. Phase identifications and chemical composition of the layer and bulk material (substrate) were determined by electron diffraction and energy dispersive X-ray spectrometry. Atomic force microscopy was applied for layer surface topography measurements. Microhardness and Young’s modulus measurements as well as frictional wear resistance and corrosion resistance tests were performed. The investigation revealed a clear correlation between the micro/nanostructure and surface topography of the layer with its micromechanical, tribological and corrosion properties. In-vitro examinations of biofilm and cell behaviour show that the nitrided Ti-6Al-4V alloy exhibits good biocompatibility.
Physicochemical Characterization of Novel Chitosan-Soy Protein/ TEOS Porous Hybrids for Tissue Engineering Applications
Authors: Silva S.S. , Oliveira J. Miguel , Mano João F. , Reis Rui L.
Published: March 2009

In this paper we report a new type of cross-linked porous structure based on a chitosansoy protein blend system developed by means of combining a sol-gel process with the freeze-drying technique. The final structure was investigated by Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), contact angle measurements and the morphology by scanning electron microscopy (SEM). The water uptake capability and the weight loss were
measured up to 14 days and their mechanical properties were assessed with compression tests. Results showed that the addition of tetraethyl orthosilicate (TEOS) to the chitosan-soy protein blend system provide specific interactions at the interface between the two polymers allowing to tailor the size and distribution as well as the degradation rate of the hybrids. Finally, TEOS incorporation induces an increase of the surface energy that influences the final physicochemical properties of the materials.
Surface Texture Development in KrF Excimer Laser Ablation of Dentin
Authors: Sivakumar M. , Vilar Rui , Oliveira Vitor
Published: March 2009

In the present paper, the influence of tubule orientation and areal density on the
development of surface textures by excimer laser processing of dentin is analysed. Disks of dentin 2 mm thick were extracted from caries-free human teeth by cross-sectional cutting above the pulp cavity, polished and fixed using standard procedures. The samples were laser-processed using 100 laser pulses of 248 nm wavelength radiation at a fluence of 1 J/cm2, pulse duration of 30 ns and
pulse frequency of 5 Hz. The surface texture after processing depends on the angle between the tubules and the laser beam. In inner dentin, where tubules are parallel to the laser beam, cone-like artefacts form, considerably increasing surface roughness. The cones are constituted by partially melted peritubular dentin and develop because the ablation rate of peritubular dentin is lower than the ablation rate of surrounding intertubular dentin. The areal density of cones is roughly identical
to the areal density of tubules except when the tubule density is high enough to allow adjacent cones to coalesce. In outer dentin, where tubules are tilted with respect to the laser beam, the surface remains flat. The reason for this orientation dependence is that, when tubules are tilted towards the laser beam, preferential removal of intertubular dentin will expose an increased area of underlying peritubular dentin to laser radiation preventing cone development.
Decay and Conservation of Building Stones on Cultural Heritage Monuments
Authors: Rives Vicente , Talegon Jacinta Garcia
Published: March 2009

Preservation of our Historical Cultural Heritage built in stone requires studies on the
material itself, on the environment where the monument is located, and even on the microclimate
affecting a particular stone in the building. The knowledge of the decay processes, as well as
mechanisms governing these processes, and the real effect of factors depending on the intrinsic
properties of the material to be studied, and external agents of decay, will allow a rationale use of
these materials and to anticipate their behaviour beforehand, in order to success in restoration
On the Structural Evaluation of Unbiased W-O-N Sputtered Coatings
Authors: Parreira Nuno M.G. , Carvalho Nuno J.M. , Cavaleiro Albano
Published: March 2009

Tungsten oxynitride films (WOxNy) were deposited with a chemical composition in the range of 0 < x < 1 and 0 < y < 1. For the W-N system, the α-W, β-W, and β-W2N phases were identified according to the amount of nitrogen. In the W-O-N system the structure depended on the amount of oxygen. For an oxygen fraction, fO2 = CO/(CO+CN), smaller than 0.46 the β-W2N phase is evident, whereas above that value the structure became amorphous.
The Effect of Surface Pretreatment on Water Absorption and Wet Adhesion of Organic Coatings
Authors: Harun Mohamad Kamal , Ismail S.N.A.S. , Yahya M.Z.A. , Lyon Stuart B.
Published: March 2009

A study was conducted on the effects of surface pre-treatment with 3-
aminopropyltriethoxysilane (3-APS) on the water absorption and adhesion behaviour of two
commercial alkyd and epoxy polyamide organic coatings on mild steel and glass substrates. The
results indicated that using 3-APS as surface pre-treatment prior to coating resulted in a significant
reduction of total water absorption for alkyd on both mild steel and glass substrate. Subsequently ile
adhesion of alkyd is enhanced on both pre-treated mild steel and glass substrate. However 3-APS
pre-treatment of mild steel increases water absorption of epoxy and lowers its adhesion strength.
While 3-APS pre-treatment of glass reduces water absorption of epoxy and subsequently enhances
the overall wet adhesion. These data are consistent with the known adsorption behaviour of 3-APS
to steel, i.e. as an easily hydrolysed hydrogen-bond to the amine group, rather than as the more
stable metal-oxide-silicon bond.