bluuebunny/crossref_metadata_2025 huggingface dataset:
Onset of Microplasticity in Copper Crystal during Nanoindentation
Authors: Horníková Jana , Černý Miroslav , Šandera Pavel , Pokluda Jaroslav
Published: March 2009

The nanoindentation test in the dislocation free crystal of copper is simulated by finite
element calculations coupled with ab initio calculation of ideal shear strength. The onset of
microplasticity, associated with the pop-in effect identified in experimental nanoindentation tests
(creation of first dislocations), is assumed to be related to the moment of achieving the value of the
ideal shear strength for the copper crystal. This value also depends on the normal stress in the
critical shear system in an approximately linear way, as follows from recently published first
principle calculations. The calculated values of the critical shear stress (related to the ideal shear
strength) lie exactly at the lower limit of the range of experimentally observed pop-ins in the copper
crystal.
Crack-Tip Stress Fields in FGMs under Anti-Plane Shear Impact Loading Using the Non-Local Theory
Authors: Bi Xian Shun , Cai Xue Feng , Zhang Jian Xun
Published: March 2009

A crack in an infinite plate of functionally graded materials (FGMs) under anti-plane
shear impact loading is analyzed by making use of non-local theory. The shear modulus and mass
density of FGMs are assumed to be of exponential form and the Poisson’s ratio is assumed to be
constant. The mixed boundary value problem is reduced to a pair dual integral equations through
the use of Laplace and Fourier integral transform method. In solving the dual integral equations, the
crack surface displacement is expanded in a series using Jacobi’s polynomials and Schmidt’s
method is used. The numerical results show that no stress singularity is present at the crack tip. The
stress near the crack tip tends to increase with time at first and then decreases in amplitude and the
peak values of stress decreases with increasing the graded parameters.
Seismic Damage Model for Steel Reinforced High Strength and High Performance Concrete Frame Joints
Authors: Zheng Shan Suo , Zheng Lei , Li Lei , Che Shun Li , Zhang Liang
Published: March 2009

Based on damage mechanics and failure model, a seismic damage model applying to steel
reinforced high strength and high performance concrete frame joints is put forward, which takes
deformation and cumulative damage into account. The damage performance of five tentative frame
joints is compared and analyzed according to deformation and dissipated hysteretic energy under
different loading levels, and the main influence factors on damage performance are established. The
damage indexes of tentative frame joints are calculated, and the influence of strength grade of
concrete and axial compression ratio on damage performance is discussed. The results indicate that
the general damage is controlled by the damage of concrete in the earlier stage of loading, and by the
damage of shape steel and stirrup in the later stage of loading; joints with lower axial compression
ratio and lower concrete strength grade possess better hysteretic energy performance. Damage
analysis provides an available means for the research of steel reinforced high strength and high
performance concrete frame joints under seismic load. The damage model presented can be a
reference for seismic damage analysis of the structure, prediction of earthquake damage in future,
estimation of economic loss and repair after earthquake.
Characteristics of Fracture Mechanics for Crack Tip near the Interface between Steel and Concrete in Composite Structures
Authors: Zheng Shan Suo , Li Lei , Che Shun Li , Zeng Lei , Zheng Jie
Published: March 2009

Steel-concrete composite structures are widely used in high buildings for its excellent
seismic behaviors, whereas faults or cracks, which have great influence on interfacial mechanical
behaviors of structural members, inevitably form near the interface between steel and concrete during
the process of molding. Therefore, it is necessary to study the mechanical characteristics of the crack
tip near the interface. In this paper, the application scope of the path-independence of J-integral in
steel-concrete composite structure with a crack is discussed. According to the conservation law of
J-integral for the steel-concrete composite structure with a crack parallel to the interface, a hypothesis
that the value of strain energy release rate (SERR) of the mode-$fracture is independent of the crack
location when the crack is parallel and close to the interface is put forwarded. And this hypothesis is
verified through finite element method (FEM). A schematic model for a skew crack near the
steel-concrete interface is provided. The variation law of SERR with the Dundur’s parameters and the
angle between crack direction and interface are calculated by FEM. At last, calculating method of the
stress intensity factor as well as the SERR for a skew crack near the interface is suggested. All these
may contribute to further investigation on interfacial mechanical behaviors for steel-concrete
composite structure.
Theoretical Analysis and Experimental Study on Damage Probability of HSHP Concrete
Authors: Zheng Shan Suo , Che Shun Li , Zheng Lei , Li Lei , Zheng Jie
Published: March 2009

Damage probability is a new concept in modern engineering design. If the cumulative
damage probability of member or material is known, then the rational design can be realized. Based
on study of high-strength and high-performance (HSHP) concrete applied to steel reinforced concrete
(SRC) structures, the equation of the cumulative damage probability of HSHP concrete is derived by
Weibull theory. The calculation and analysis indicate that the theoretical equation presented give a
suitably mathematical limit for damage probability of specimens. At the same time, the new method
for Weibull parameters is established, which depends on the theory of the damage probability and
computer graphics technology. The comparison of experimental curves with theoretical curves shows
that the established equation can properly simulate the damage evolution of HSHP concrete.
Them value, one of Weibull parameters, is studied in detail, which reveals that it is a key parameter to
quality control. At last, the effect of specimen volume upon damage probability is also discussed. The
research provides methods and ideas to improve performance of concrete material and simulate
damage probability of HSHP concrete.
Numerical and Experimental Investigations of Curved Fatigue Crack Growth under Biaxial Proportional Cyclic Loading
Authors: Theilig Holger , Hartmann D. , Wünsche Michael , Henkel S. , Hübner P.
Published: March 2009

The paper presents numerical and experimental results of continued studies of curved
fatigue crack growth in arbitrarily pre-cracked isotropic sheets under biaxial proportional plane
loading. The predictor-corrector method (PCM) was extended in order to analyse the growth of
multiple crack systems. As a result, the program PCCS-2D was written to run within ANSYS without
any user interaction. In order to check the accuracy and efficiency of the method biaxial crack
growth simulations were carried out for a fracture mechanics cruciform specimen. The results are
compared with experimental findings obtained by specimens made of 6061 aluminium alloy in
T651 condition using a 250kN biaxial servohydraulic testing machine. From the numerical and experimental
results, we conclude, that the proposed predictor-corrector method can be used in curved
crack growth simulation also under biaxial proportional loading conditions.
Damage Mechanisms of Initiating Micro-Pitting on 42CrMo4 Hardened and Tempered Steel
Authors: D'Errico Fabrizio , Boniardi Marco , Barella Silvia , Cincera Silvia
Published: March 2009

A deep comprehension of the damage mechanisms involved in contact fatigue should
optimize material and heat treatment choice for a specific application.
In this work rolling disc-on-disc contact fatigue tests have been performed on a hardened and
tempered UNI EN 42CrMo4 .
The adopted test method creates the best conditions in order to develop micro-pitting on disc
surface.
Extensive micro-fractographic examinations have been carried out, on the damaged surfaces,
through a scanning electronic microscope (SEM).
For this steel, loaded with Hertzian pressure of 1000 MPa, the failure mode is always micro-pitting
which begins at the surface, and it is not a sub-superficial damaging.
If micro-pits develop, they will coalesce in larger craters. By this way, the probability that micropitting
will degenerate into sub-superficial destructive pitting is very high.
Influence of Microstructure on Mechanical Properties of an AZ91D Thixomolded® Magnesium Alloy
Authors: D'Errico Fabrizio , Boniardi Marco , Perricone Guido , Vujanovic Dragutin
Published: March 2009

The Thixomolding® process has a 20-year track record of research with commercial
applications beginning in 1992. The apparatus machine is similar to those used for an injection
plastic molding: it transforms in a single step magnesium chips heated to a semisolid slurry (inside a
barrel and screw) into precision molded parts. Originally employed by Asian manufacturers for
consumer electronics and consumer hardware applications (such as notebook computer cases,
digital camera bodies and chain saw housings, etc.), the industrial uses of Thixomolding® has been
widely extending from last years to other parts suppliers in the Americas, Europe and Asia.
Nowadays thixomolded parts there are in automotive and sport equipment as automotive shift cams,
bike saddle, fishing reels, snowboard bindings, etc. Thanks to the semisolid and thixotropic state of
magnesium, the slurry moves in laminar flow inside the mould. The absence (or very low) of
turbulence allows to reduce drastically (and often to eliminate) residual porosity which is typical of
die-casting. In this work a thixomolded AZ91D has been characterized by tensile and axial fatigue
testing (fatigue ratio R=0.1) both in the as-supplied condition and after a Tx heat treatment.
Mathematical Model for Shear Stress-Strain Relationship of Soil-Concrete Interface during Shear Fracture Process
Authors: Wang Wei , Lu Ting Hao , Sun Bin Xiang
Published: March 2009

Description of shear stress-strain relationship for soil-concrete interface during shear
fracture process plays an important role in experimental and numerical studies of soil-structure
interaction. In this paper, deficiency of traditional hyperbolic model for the shear stress-strain
relationship is analyzed, firstly. Then, a new model with 3 parameters for it is established, which can
overcome the deficiency of hyperbolic model. Finally, good agreements have been found between the
proposed model and laboratory tests.
Comparison of Dynamic and Fatigue Properties of Virgin and Recycled Asphalt Mixture
Authors: Wu Shao Peng , Qiu Jian , Shui Zhong He , Wang Hui Ju
Published: March 2009

Recycled asphalt mixture is a multiphase system, which consists of sized recycled asphalt
pavement (RAP), new asphalt, and/or recycling agents and new aggregates. RAP percentages may
have influences on performance of total recycled asphalt mixture. The performance of asphalt mixture
is significantly affected by its dynamic response and fatigue performance (crack formation and
propagation). Dynamic and fatigue properties of virgin and recycled asphalt mixture are investigated
based on Indirect Tensile Test (ITT). It is demonstrated in test results that recycled asphalt mixture is
stiffer and more elastic-like than virgin ones with RAP added. The number of load cycles to fatigue
failure expected of recycled asphalt mixture is a bit decrease compared with that of virgin ones in low
stress level. In addition, high fatigue resistance of recycled asphalt mixture is observed in this test
when stress level is high.
Fracture Parametric Study on Bond Behaviour between FRP Laminates and High Strength Concrete with Experiments
Authors: Li Hong Nan , Zhou Ying Wu , Wang Su Yan , Liu Gui
Published: March 2009

Recently, concrete structures deteriorating for various reasons and upgrading by bonding
FRP using epoxy resins has attracted significant researches. Experimental studies in literates
indicate that the anchorage between concrete and FRP laminates plays an important role in the
reinforcing design. However, few and no special study has extended to high strength concrete. This
research examines the bond behaviour between FRP laminates and high strength concrete. To
obtain the bond strength and regulation of debonding propagation, a simple face shear type bond
test is conducted. With the explicit material and geometric descriptions and the fairly general
boundary conditions, the interfacial fracture energy release rate, Gf of this test model which is then
used to propose the prediction of the bond strength is derived. Comparison of this energy basis
model in prediction of bond strength with the model of Chen & Teng which has a high accuracy in
this area and results from this experiment demonstrates the derived prediction model as a feasible
and effective measure in analyzing the bond behaviour between FRP and high strength concrete.
Retrofit of Artificially Perforated Shear Wall in Existing Dominant Wall Structure
Authors: Choi Chang Sik , Choi Yun Cheul , Choi Hyun Ki , Lee M.S.
Published: March 2009

A series of three shear wall specimens were tested under constant axial stress and
reversed cyclical lateral loading in order to evaluate the seismic retrofit that had been proposed for
the shear wall with the opening induced by remodeling. One of these specimens was tested in the
as-built condition and the other two were retrofitted prior to testing. The retrofit involved the use of
carbon fiber sheets and steel plates (a thickness of 3mm) over the entire face of the wall. The test
results showed that the failed specimens had shear fractures and that two different types of
retrofitting strategies had different effects on the strengths of each specimen.
Evaluation of Fatigue Strength of Fillet Welded Connections with Respect to Different Post-Weld Treatment Methods
Authors: Kyung Kab Soo , Lee Seung Yong , Lee Sung Geun , Kim Kwang Seok
Published: March 2009

In the study herein, the fatigue test was conducted on the fillet welds of the load carrying
cruciform joint, which is frequently used in the steel structures such as bridges, ships, etc. In
addition, the fatigue stress was analyzed with respect to the different post-weld treatment. The
treatment methods used include Toe Grinding, TIG Dressing, and Weld Profiling. The fatigue test
was under constant amplitude with repeated load for these test specimens. In the load carrying full
penetration fillet welded joints, regardless the conduction of the post-weld treatment or not, they all
secured the fatigue strength of category "F", which exceeds the fatigue design specifications of BS
Code. In the comparison of the fatigue strength upon the post-weld treatment, the fatigue strength
tends to increase according to the order: Toe Grinding, TIG Dressing, and Weld Profiling.
Dynamic Loads and Strength Requirements for Flapping Wing
Authors: Dabnichki Peter , La Mantia Marco
Published: March 2009

The study is part of a wider biomimetic investigation focusing on flapping wing in water
- penguin wing. The long-term aim is to design a hybrid vehicle capable of flying in fluids with very
different densities. The paper analyses the dynamic loads on an oscillating wing used for obtaining
the trust generated throughout harmonic motion. The strength requirements for such wing have not
been analysed up to now and this study is to be followed shortly by experimental simulation in a
wind-tunnel. The acting forces in the current analysis were obtained through a potential flow based
panel method computer program.
CO2 Absorption Properties of Barium Orthotitanate under Continuous Operation
Authors: Marusawa Hiroshi , Saito Yoshinori
Published: March 2009

Barium orthotitanate ceramics (Ba2TiO4) with ≧0.4wt% Nickel shows highly reproducible CO2 absorption - desorption when they are annealed under cyclic temperature conditions. Addition of Ni powder prohibited the grain growth of the Ba2TiO4 ceramic.
Lithium Intercalation Properties of Porous Anatase TiO2 with Bimodal Pore Size Distribution
Authors: Suzuki Shinya , Ogawa Akira , Miyayama Masaru
Published: March 2009

The lithium intercalation properties of anatase TiO2 electrodes with a bimodal pore size distribution
were examined. Porous anatase TiO2 was prepared by hydrolyzing titanium tetrabutoxide using
polyoxietylene cetyl ether as a surfactant and its subsequent calcination at 500°C for 4 hours. A
porous anatase TiO2 electrode with a relatively large pore volume and 50-nm-diamater pores
showed a discharge capacity of approximately 150 mAh g-1. It maintained a relatively large
discharge capacity of 125 mAh g-1 at a current density of 1 A g-1, and exhibited a good high-rate
capability.
Magnetic and Dielectric Properties of a Metal/ Cr2O3/Cr2O3-x/Cr2O3/Semiconductor Capacitor Using Magneto-Electric Materials
Authors: Yokota Takeshi , Kuribayashi Takaaki , Shundo Takeshi , Hattori Keita , Sakakibara Yasutoshi , Gomi Manabu
Published: March 2009

We investigated the magnetic and dielectric properties of a metal (Pt)/insulator
(Cr2O3)/semiconductor (Si) (MIS) capacitor composed of magneto-electric (ME) materials. The
capacitor has anti-ferromagnetic properties and a very small electrically induced magnetic moment.
It also shows capacitance-voltage (C-V) properties typical of a Si-MIS capacitor without any
hysteresis. By inserting a thin Cr2O3-x layer, the C-V curve has a hysteresis window with a
clockwise trace, which indicates that electrons have been injected into the Cr2O3-x layer. These
results indicate that this MIS capacitor contains a floating gate and an ME insulating layer in a
single system.
Cathodoluminescence of Single Phase ZnAl2O4 and Diffusion Layer Synthesized by Coupling of ZnO and α-Al2O3
Authors: Suzuki Kenichi , Kuroki Yuichiro , Okamoto Tomoichiro , Takata Masasuke
Published: March 2009

Zinc oxide (ZnO) ceramics was coupled and reacted with alpha aluminum oxide (α-Al2O3) ceramics at 1200oC for 24 h. SEM observation and energy dispersive X-ray spectroscopy (EDS) analysis revealed the existence of diffusion layer of 10 μm thickness on the α-Al2O3 side of interface between ZnO and α-Al2O3. The diffusion layer is considered to consist of a ZnAl2O4, from the result of XRD. The cathodoluminescence of the diffusion layer was compared with that of zinc aluminate (ZnAl2O4) ceramics synthesized by conventional solid state reaction method. The single phase ZnAl2O4 showed weak emission peaked at 4.6 eV. On the other hand, the diffusion layer showed intense emission peaked at 3.75 eV. The ZnAl2O4 on the α-Al2O3 side of the interface synthesized by coupling of ZnO and α-Al2O3 is considered to be a excellent material as an ultraviolet light emitter.
Electromechanical Poling Treatment of Barium Titanate Single Crystals and their Piezoelectric Properties
Authors: Muraishi Tomomitsu , Yokoh Keisuke , Kakemoto Hirofumi , Tsurumi Takaaki , Wada Satoshi
Published: March 2009

The phase transition behaviors of the [111]c oriented barium titanate (BaTiO3) single crystals (the
subscript c means the cubic notation system) were investigated as functions of temperature, uniaxial
stress and electric fields. These results suggested that above Tc, combination between uniaxial stress
and electric fields might be effective for a poling treatment of BaTiO3 single crystals. Thus, a new
poling method for BaTiO3 single crystals was proposed using control of temperature, uniaxial stress
and electric fields in this study.
Introduction of Fine Engineered Domain Configuration into Potassium Niobate Single Crystals
Authors: Yokoh Keisuke , Muraishi Tomomitsu , Nam Song Min , Kakemoto Hirofumi , Tsurumi Takaaki , Kumagai Hirohiko , Wada Satoshi
Published: March 2009

To induce fine engineered domain configurations into potassium niobate (KNbO3) single crystals, two kinds
of methods were performed, i.e., (1) high DC electric field exposure along the opposite direction of
polarization of KNbO3 single-domain crystals at room temperature, and (2) introduction of randomly
oriented fine domain configuration by heat treatment at 700 °C and then high DC electric field exposure
along [001]c direction of KNbO3 multidomain crystals at room temperature. When the method (1) was
performed, finally, the poled KNbO3 crystals became to single-domain state again through the formation of
multidomain state. On the other hand, the KNbO3 multidomain crystals were obtained by using the method
(2), and an enhancement of piezoelectric-related properties was observed.
High Temperature Mechanical Property of Al2O3 Coated Quartz-Fiber Reinforced Methyl Silicon Resin Composites
Authors: Wang Lei , Huang Yu Dong , Liu Li
Published: March 2009

In the present work, Al2O3 was coated on the quartz fiber by the sol-gel method to improve the high temperature mechanical properties of the quartz fiber/methyl silicon resin composites. The X-ray diffraction results showed that the crystalline property of the Al2O3 coating increased with the processing temperature. Before 500oC treated, the Al2O3 coated fiber reinforced composites have lower flexural strength than the commercial fiber reinforced one. While after 500oC treated, the flexural strength of Al2O3 coated fiber reinforced composites was higher than the uncoated reinforced one. And the flexural strength for the 400oC treated Al2O3 coated fiber reinforced composites was higher than that of the 600oC treated one. The mechanism of the crack propagation in the purchased and Al2O3 coated fiber reinforced composites was also studied through scanning electronic microscopy (SEM).
Thermomechanical Properties of Nanosilica Reinforced PEEK Composites
Authors: Lai Y.H. , Kuo M.C. , Huang J.C. , Chen M.
Published: March 2009

The nano-sized silica particulates reinforced poly(ether ether ketone) (PEEK) composites were fabricated by means of simple compression molding technique. The nano-sized silica, measuring 30 nm in size, was firstly modified by surface-pretreatment with stearic acid. The thermomechanical properties of the resulting PEEK/SiO2 nanocomposites were measured using dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA). The TMA results show that the coefficient of thermal expansion (CTE) becomes lowered when the content of the nanosilica increases. Furthermore, the CTE of the modified-silica filled PEEK nanocomposites shows higher CTE values, as compared with those of the unmodified counterparts. The dynamic modulus of the PEEK nanocomposites shows over 40% increment at elevated temperatures from 100-250oC, indicating the apparent improvement of elevated temperature mechanical properties.
Wettability and its Improvement at Al/SiC Interfaces
Authors: Ouyang Qiu Bao , Zhou Wei Min , Zhang Guo Ding , Zhang Di
Published: March 2009

The objective of the present paper is to study the wetting phenomenon and improving methods of Al/SiC interfaces. The work of adhesion and contact angle of this system was calculated theoretically from the physicochemical model. The effects of alloy elements such as Mg and the processing temperature on wettability were also investigated theoretically. Based on the theoretical calculation results, some effective methods to improve the wettability were presented.
Densification Mechanism of SnO2 Ceramics Doped with 5.0 mol% MnO2
Authors: Luo Guo Qiang , Li J. , Zhang Dong Ming , Shen Qiang , Zhang Lian Meng
Published: March 2009

Dense SnO2 based ceramics are widely used. In this paper, 95SnO2-5MnO2 ceramics were prepared by pressureless sintering in air at different temperatures. Phase compositions and microstructures are examined by XRD, SEM and EDX, respectively. The SEM results show that different morphologies exist at the SnO2 grain boundary of ceramic, which compose of manganese oxidation, testified by EDX. The different manganese oxides phases, found by XRD, are the source of oxygen concentration at the grain boundary during heating and oxygen dissipation when cooling. However, solid solutions of Mn, Sn and O are not observed. The density of 95SnO2-5MnO2 ceramics decreases with increasing the sintering temperature, due to the evaporation of SnO and decreasing concentration of oxygen at grain boundary in the cooling process. Densification of the ceramic is promoted with inhibiting the decomposition of SnO2 by increasing oxygen concentration in the heating process, but it is limited by the dissipation of oxygen at the grain boundary in the cooling process.
Ca-SiAlON Glasses: Effects of Fluorine on Glass Formation and Properties
Authors: Hampshire Stuart , Hanifi Amir R. , Genson Annaik , Pomeroy Michael J.
Published: March 2009

Oxynitride glasses are effectively alumino-silicate glasses in which nitrogen substitutes for oxygen in the glass network, resulting in increases in glass transition and softening temperatures, viscosities (by two to three orders of magnitude), elastic moduli and microhardness. Calcium alumino-silicate glasses containing fluorine are known to have useful characteristics as potential bioactive materials. Therefore, the combination of both nitrogen and fluorine additions to these glasses may give useful bioglasses with enhanced mechanical stability. This paper gives a review of oxynitride glasses and reports glass formation and evaluation of glass properties in the Ca-Si-Al-O-N-F system. Within the previously defined glass forming region in the Ca-Si-Al-O-N system, homogeneous, dense glasses are formed. However, addition of fluorine affects glass formation and reactivity of the glass melts and can lead to fluorine loss as SiF4, but also nitrogen loss, and cause bubble formation. At high fluorine and high Ca contents under conditions when Ca- F bonding is favoured, CaF2 crystals precipitate in the glass. It was found that fluorine expands the glass forming region of Ca-Sialon system and facilitates the solution of nitrogen into the melt.
Thermal Conductivity Improvement by Heat-Treatment in Si3N4 Ceramics Using SiO2-MgO-Y2O3 Additive System
Authors: Wasanapiarnpong Thanakorn , Wada Shigetaka , Imai Masamitsu , Yano Toyohiko
Published: March 2009

Silicon nitride (Si3N4) ceramics have been interested for electrical substrate applications,
because the ceramics can be made highly mechanical strength, fracture toughness, electrical
resistivity and high thermal conductivity. Generally, relatively large amount of additives are
required to obtain dense Si3N4 ceramics. During sintering, additives react with SiO2 including
surface oxide of Si3N4 raw powder to form a liquid phase. Most of liquid phase changed into glassy
phase during cooling down. In this study, Si3N4 ceramics were fabricated by gas pressure sintering.
Yttrium oxide (Y2O3), silica (SiO2), and magnesia (MgO) were used for liquid-phase-enhanced
sintering process. Dense materials were sintered by this process, but their thermal conductivities
were not so high (30-40 W/m·K). Therefore, post-sintering heat-treatment process was performed
to reduce the excess amount of glassy phase.
An additive system (3 mass% SiO2 with 3 mass% MgO and 1-5 mass% Y2O3) was selected as
the sintering aid. These ceramics could be sintered to almost full density at relatively low
temperature as 1650oC for 2 h under 0.1 MPa-N2 without packing powder. The resulting materials
have high bending strength, about 1 GPa, when 5mass% of Y2O3 was added.
Based on the creation of low temperature pressureless sintering without packing powder, a novel
two-step sintering (once firing) was proposed. The two-step sintering conducted by sintered at
1650oC under 0.1 MPa-N2 for 2 h for densification in the first step. Followed by heated up to and
kept at 1950oC for 8 h under 1.0 MPa-N2 in the second step. The Si3N4 ceramics could be
fabricated with relatively high thermal conductivity of 90 W/m·K. Mass loss, microstructure,
mechanical properties, oxygen content and chemical composition were discussed.
Step Free Energy Change and Microstructural Development in BaTiO3-SiO2
Authors: Chang Jaem Yung , Kang Suk Joong L.
Published: March 2009

The effect of step free energy on the grain growth behavior in a liquid matrix is studied in a model system BaTiO3-SiO2. BaTiO3-10SiO2 (mole %) powder compacts were sintered at 1280°C under various oxygen partial pressures (PO2), 0.2, ~ 10-17 and ~ 10-24 atm. As the step free energy decreases with the reduction of PO2, it was possible to observe the change in growth behavior with the reduction of the step free energy. At PO2 = 0.2 atm, essentially no grain growth (stagnant grain growth) occurred during sintering up to 50 h. At PO2 ≈ 10-17 atm, abnormal grain growth followed stagnant grain growth during extended sintering (incubation of abnormal grain growth). At PO2 ≈ 10-24 atm, normal grain growth occurred. These changes in growth behavior with PO2 and the step free energy reduction are explained in terms of the change in the critical driving force for appreciable growth relative to the maximum driving force for grain growth. The present experimental results provide an example of microstructure control in solid-liquid two- phase systems via step free energy change.
Electrochemical Properties of Cathode for Solid Oxide Fuel Cell
Authors: Shimonosono Taro , Hiramatsu Go , Hirata Yoshihiro , Sameshima Soichiro , Matsunaga Naoki , Doi Toshiya , Horita Teruhisa
Published: March 2009

Electrochemical properties (terminal voltage, ohmic resistance and overpotential) were
measured for the cell of indium tin oxide cathode (ITO, 90 mass% In2O3-10 mass% SnO2) or
perovskite-type oxide cathode La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) / Gd-doped ceria electrolyte
(Ce0.8Gd0.2O1.9, GDC, 600-700 μm thick)/Ni-GDC anode using 3 vol% H2O-containing H2 fuel at 873
and 1073 K. The maximum power densities for the cell with ITO cathode at 873 and 1073 K were 21
and 71 mW/cm2, respectively. Similarly, the maximum power density with LSCF was 12 and 113
mW/cm2 at 873 and 1073 K, respectively. The voltage drop was larger for the cathode than for the
electrolyte or anode. The overpotential of the LSCF cathode was comparable to the ohmic resistance.
High Oxygen Storage Ceria-Zirconia Solid Solutions Synthesized by Atmospheric Pressure Solvothermal Process
Authors: Suda Akihiko , Yamamura Kae , Morikawa Akira , Nagai Yasutaka , Sobukawa Hideo , Ukyo Yoshio , Shinjo Hirofumi
Published: March 2009

Ceria-zirconia solid solution is one of the most important components of three way catalyst
(TWC) for cleaning automotive exhaust. Ceria-zirconia solid solution has a function as an oxygen
storage material, which keeps air to fuel ratio (A/F) at the surface of TWC on a stoichiometric
composition. The dissolved zirconia into ceria lattice makes cerium ions to be reduced easier and
enhances especially bulk oxygen to release. However, there is a large difference of oxygen storage
capacity (OSC) between a theoretical value and that of the prior ceria zirconia solid solutions. The
cause of the large difference of OSC might be come from the inhomogeneous dispersion of Zr ions in
ceria lattice. Atmospheric pressure solvothermal (APS) process was applied to ceria-zirconia solid
solutions in this study. The APS ceria-zirconia showed excellent OSC. The excellent OSC
performance was presumed to come from further uniformity of zirconium ions in the ceria lattice.
Formability of Hydroxyapatite on Beta-Type Ti-Nb-Ta-Zr Alloy for Biomedical Applications through Alkaline Treatment Process
Authors: Akahori Toshikazu , Niinomi Mitsuo , Nakai Masaaki
Published: March 2009

Titanium and its alloys have been widely used as biomaterials for hard tissue replacements
because of their excellent mechanical properties and biocompatibility. However, the bonding between
their surfaces and bone is not enough after implantation. The bioactive surface modification such as a
hydroxyapatite (HAp) coating on their surfaces has been investigated. Recently, a simple method for
forming HAp layer on the surfaces of titanium and its alloys has been developed. This method is
called as alkaline treatment process. In this method, HAp deposits on the surfaces of titanium and its
alloys by dipping into simulated body fluid (SBF) after an alkaline solution treatment that is followed
by a baking treatment (alkaline treatment). This process is applicable to newly developed beta-type
Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) for biomedical applications achieving bioactive HAp
modification. In this study, the morphology of the HAp layer formed on the surface of TNTZ was
investigated after various alkaline treatments followed by dipping in SBF. The formability of HAp on
the surface of TNTZ was then discussed. The formability of HAp on TNTZ is much lower than that of
commercially pure Ti, Ti-6Al-4V ELI and Ti-15Mo-5Zr-3Al alloys, which are representative metallic
biomaterials. The formability of HAp on TNTZ is improved by increasing the amount of Na in the
sodium titanate gels formed during an alkaline solution treatment where the NaOH concentrations
and the dipping time are over 5 M and 172.8 ks, respectively. The formability of HAp on TNTZ is
considerably improved by dipping in a 5 M NaOH solution for 172.8 ks. This condition for alkaline
solution treatment process is the most suitable for TNTZ.
In Vitro Evaluation of RF Magnetron-Sputtered Calcium Phosphate Films on Titanium
Authors: Ueda Kyosuke , Narushima Takayuki , Katsube Tomoyuki , Kawamura Hiroshi , Goto Takashi
Published: March 2009

Calcium phosphate coating films were fabricated on mirror-polished or blast-treated titanium substrates using radio-frequency (RF) magnetron sputtering and they were evaluated in vitro. Immersion tests for the films were conducted using phosphate-buffered saline (PBS(-)), and apatite formation and the elution of calcium ions from the films were investigated. The bonding strengths between the calcium phosphate films and titanium substrates before and after the immersion tests were evaluated. After the immersion tests, a decrease in the bonding strength was observed for the coating films on the mirror-polished titanium substrates, while that for the blast-treated titanium substrates was almost the same as that before the immersion tests.
Interface Strength of Low-Dimensional Nano-Components
Authors: Kitamura Takayuki , Hirakata Hiroyuki , Takahashi Yoshimasa
Published: March 2009

The interface strength of low-dimensional nano-components such as films and islands
formed on substrates has been investigated in this project, and the focus is put on the mechanics of
crack initiation from the free interface edge and propagation along the interface. The series of
experiments elucidates the applicability of fracture mechanics concept on the structures. We proposed
experimental methods for evaluating the initiation strength of an interface crack in submicron films
and islands deposited on substrates. The initiation is governed by the singular stress field, and the
criterion is prescribed by the stress intensity parameter. Using special loading apparatus built in a
TEM, we developed a crack initiation method for nano-components and the role of plasticity on the
delamination is clarified. Subcritical crack growth along an interface between submicron films under
fatigue was also investigated by modified four-point bend method.
Numerical Simulation of Rock Stability under Dynamic Blasting Load
Authors: Xiao Fu Kun , Sun Guang Yi , Tian Li Hui
Published: March 2009

In order to study the effect of blast shake on the stability of tunnel during mining process,
finite element analysis software for rock and soil engineering is used to simulate the effect of
blasting shake. In the simulation, a short-time dynamic load is applied to the rock in the blasting
zone. Dynamic stress field in the rock mass and distortion in the surface of the tunnel are calculated
with the finite-element method. Equivalent displacement method is utilized to determine the amount
of sudden applied load, the actuation duration and the range of action. Consequently, the maximum
critical explosive content at the critical shake speed of rock mass can be defined.
The Variation of Crack Energy Density (CED) on Creep Crack Growth
Authors: Jeong C.S. , Nam Byeung Gun , Watanabe Katsuhiko
Published: March 2009

Creep crack growth (CCG) rate has been organized frequently by C* or Ct parameter
However, crack behavior of early stage under unsteady state condition has not been explained.
Crack energy density (CED), which has been proposed as a parameter that can provide a unified
description of crack behavior with no restriction on constitutive equation, can give the general
expression about creep crack growth rate. By applying Ct and the concept of CED to the results, we
showed that creep crack growth rate for all ranges of creep can be explained in a unified way by
CED and its derivatives. Moreover, the physical meaning of the Ct is clarified in the discussion.
Thermal Strength Evaluation of the Super Alloy Structure with Various Thermal Insulation Performances by FEM and Stress-Rupture Experiment
Authors: Lee Je Jun , Lee Young Shin , Kim Jae Hoon , Byun Seong Woo , Koo Song Heo , Moon Soon Il
Published: March 2009

The combustor chamber, diffuser and nozzle are the main components of the ramjet
engine. In this study, the thermal strength of the combustion chamber of the ramjet engine was
evaluated. The combustion chamber consists of an Inconel alloy 718 liner and a 17-4Ph stainless
steel housing. The liner is rapidly heated to a high temperature. The heated liner is cooled with a
film cooling method that forms a cold boundary layer to separate the hot gas from the surface of the
liner. The thermo-structural analysis is evaluated the thermal strength of super alloy structure with
various thermal insulation performances by finite element method with code MSC/Nastran. The
result of the analysis is compared with accelerated stress rupture test. The experiment is performed
to get safety design and estimate actually life-time for combustor chamber under high temperature.
In general, the work in this paper is helpful to further improve the understanding and evaluation of
thermal strength of the super alloy structure with various thermal insulation performances.
Fatigue Strength of Metals Containing Inclusions and Phase Inhomogeneity
Authors: Matsuno Hiroshi
Published: March 2009

Fatigue strength data of metals are picked up from literature and rearranged on the basis
of the equivalent stress ratio which has previously been proposed by the author. The characteristics
of fatigue strength are especially investigated for metals containing nonmetallic inclusions and
phase in-homogeneity. As a result, it is found that σ
w2 -type fatigue strength is often exhibited even
in a specimen without a notch and it leads to a wide range of scattering of fatigue strength of
unnotched specimens.
Simulation of Deformation Behavior in Aluminum Alloys Having Bimodal Structures Based on the Theory of Crystal Plasticity Considering Dislocation Distributions
Authors: Nakasone Yuji , Yokoi Takeshi , Sato Yasunao
Published: March 2009

The present paper describes the FEM code the present authors have developed based on the
theory of the polycrystal plasticity with dislocation distributions taken into account and the simulations
of tensile deformation behavior in FCC polycrystalline materials having bimodal structures by
using the developed FEM code. In order to simulate the deformation behavior of materials having
bimodal structures, it is necessary for the code to simulate the mesoscopic deformation behavior with
the size effect of the initial yield strength, or the 0.2% proof strength. The present study has attempted
to simulate the size effect of 0.2% proof strength by modifying the Bailey-Hirsch relation. By using
the modified relation, the size effect of the initial plastic yield is successfully reproduced by FE
polycrystal plasticity analysis. The results also showed that the 0.2% yield strength is decreased as the
volume fraction of coarse grains is increased in the bimodal structure. As the ratio of the average
diameter of fine grains to that of coarse grains is increased, the yield strength of the bimodal structure
is decreased. The yield strength and work hardening rate of the bimodal structure, however, is not so
much decreased as that of fine grain models. It was also revealed that the reason why materials having
bimodal structures show higher ductility is that coarse grains yield in earlier stage of deformation and
lower the maximum stress in the materials.
A Generalized Magneto-Thermoelastic Coupled Problem
Authors: He Tian Hu , Zhou You He
Published: March 2009

two-dimensional problem in electromagneto-thermoelasticity for a thermally and
electrically conducting half-space solid whose surface is subjected to a time-dependent heat is
studied in the context of Lord and Shulman theory. The solid is placed in an initial magnetic field
parallel to the plane boundary of the half-space. The normal mode analysis is used to obtain the
exact expressions for the considered variables. The results of the considered variables are
represented graphically. From the distributions it can be found the coupled effect and thermal wave
effect.
Evaluation of a Strain Energy Equivalence Principle (SEEP)-Based Continuum Damage Model
Authors: Lee Usik , Youn Deokki , Lee Sang Kwon
Published: March 2009

A new continuum damage theory (CDT) has been proposed by Lee et al. (1997) based on
the SEEP. The CDT has the apparent advantage over the other related theories because the complete
constitutive law can be readily derived by simply replacing the virgin elastic stiffness with the
effective orthotropic elastic stiffness obtained by using the proposed continuum damage theory. In
this paper, the CDT is evaluated by comparing the mode shapes and natural frequencies of a square
plate containing a small line-through crack with those of the same plate with a damaged site replaced
with the effective orthotropic elastic stiffness computed by using the CDT.
Combustion Synthesis of ZrW2O8 and Preparation of its Composite with Near Zero Thermal Expansion
Authors: Yan Xue , Cheng Xiao Nong , Yang Xin Bo , Zhang Cheng Hua
Published: March 2009

ZrW2O8 was successfully synthesized via combustion method with
(NH4)5H5[H2(WO4)6] ·H2O, ZrOCl2·8H2O, H3BO3, (NH2)2CO and HNO3. The best prescription of
combustion synthesizing of ZrW2O8 was obtained. The linear thermal expansion coefficient of
synthesized ZrW2O8 is -5.08×10-6oC-1 in the temperature range of 50-600oC. Different weight ratios
of ZrW2O8 and ZrO2 were taken into account. Al2O3 was added into the composite during sintering
to increase the density of the composites. When the weight ratio of ZrO2 to ZrW2O8 is 2, the
composite with near zero thermal expansion can be obtained. 0.25 wt% Al2O3 can effectively
increase the density of ZrO2/ZrW2O8 composites with slight influence on the thermal expansion
property.
Effect of Mechanical Activation on the Morphology and Microstructure of Ni-Al-Ti-B Composite Powders
Authors: Cao Guo Jian , Geng Lin , Guo Yong Liang , Naka Masaaki
Published: March 2009

In this work, Ni-Al-Ti-B composite powders with Ni: Al: Ti: B atom ratio of 5.7: 1.9:1:1
were prepared by using mechanical activation (MA) method. The MA processes were performed by
vibration ball mill in a water-cooled chamber for 30 h. The ball-to-powder weight ratio was 10:1. In
order to reduce the oxidation of the powders during milling process, ball milling was performed under
an Argon atmosphere. The evolution of morphology and microstructure of Ni-Al-Ti-B composite
powders were examined at different milling stages using scanning electron microscope and X-ray
diffraction. Distribution of powders size was analyzed and the results showed that there were three
stages for the change of powders size: (1) at the first stage, powders size increased due to more
welding than fracture of the powders within 2h of MA, (2) at the second stage, particle size
continuously decreased until 16h of MA due to more fracturing than welding, and (3) after 16h of
MA, the particle size remained constant when welding and fracture reached an equilibrium.
Calculation results according to Scherrer equation from X-ray pattern showed that the effective grain
size continuously decreased with MA time. X-ray diffraction pattern confirmed that the formation of
Ni and Ti solid solution during MA process of the Ni-Al-Ti-B composite powders.
Effect of Temperature on Strain Softening Behavior of Composites with Small Misaligned Whiskers
Authors: Li Ai Bin , Meng Qing Yuan , Geng Lin , Cao Guo Jian , You Wen Bin , Yan Yi Wu
Published: March 2009

The effect of temperature on strain softening behavior of composites with small
misaligned whiskers is investigated. The results show that the temperature affects the matrix and
whisker mechanical behavior and corresponding composite deformation behavior. With increasing
temperature, the whisker rotation angle increases, but their breakage decreases. Meanwhile
elevating temperature not only reduces the matrix flow stress and work hardening rate, but also
decreases load transfer from the matrix to the whiskers and stress induced by the whisker rotation
and breakage.It is found that during hot compression, strain softening behavior of composites
decreases as temperature increases.
Statistical Damage Detection of Laminated CFRP Beam Using Electrical Resistance Change Method
Authors: Takahashi Kosuke , Todoroki Akira , Shimamura Yoshinobu , Iwasaki Atsushi
Published: March 2009

Statistical diagnosis using electrical resistance changes is performed to detect a
delamination crack in a CFRP beam. This method enables to reduce data required for damage
identification. First, a new measuring method of multiple electrical resistance changes is proposed to
perform statistical diagnosis. The proposed method measures electrical resistance changes of multiple
segments in a CFRP beam although electrical interference must be considered when multiple voltages
are charged at once. Next, statistical diagnosis is performed on loading to the CFRP beam. A
delamination crack is detected by the change of relative relationship between multiple electrical
resistance changes due to damage occurring. As a result, the monitored states of the CFRP beam are
diagnosed exactly by the proposed damage detection system.
The Spectroscopy Characterization of Kaolinite-Organic Intercalation Materials
Authors: Wang Lin Jiang , Xie Xiang Li , Wu Da Qing
Published: March 2009

Kaolinite/formamide intercalation materials are characterized using X-ray diffraction
(XRD), Fourier transform infrared spectroscopy(FT-IR), Raman spectroscopy and 1H magic angle
spinning nuclear magnetic resonance spectroscopy (1H MAS NMR). The d(001) spacing of
kaolinite treated with formamide is 1.020nm, which is larger than that of the original clay. The 1H
MAS NMR graphs show that the proton chemical shifts of the inner hydroxyl and inner surface
hydroxyl of kaolinte are δ-1.3 and δ2.4 respectively. After formamide intercalation, the proton
peaks of the inner surface hydroxyls shifted to high-field with δ2.3, the proton peak of the inner
hydroxyl shifted to δ-0.3 toward low-field. In the hydroxyl stretching vibration region of Raman
spectrum, the formamide intercalation resulted in the decrease of the intensities of kaolinite inner
surface hydroxyl bands at 3699cm-1,3682cm-1, 3665cm-1 and 3642cm-1, and the appearance of
additional bands at 3610cm-1,3628cm-1. In the NH stretching region of FT-IR spectrum, two bands
are observed at 3336cm-1 and 3466cm-1 corresponding to the two types of the hydrogen bonds
between formamide and kaolinite. In the carboxyl stretching region, an additional band at 1667cm-1
is assigned to C=O group that bonded to the inner surface hydroxyl of kaolinite.
The Kinetic Analysis of Thermal Decomposition of PMMA/MMT Nanocomposites
Authors: Chen Kui , Yang Rui Chen , Cheng S.W.
Published: March 2009

The thermal decomposition kinetics and thermal stability of poly (methyl methacrylate)
(PMMA) and PMMA/ montmorillonite (MMT) nanocomposites containing 4 wt% MMT were
researched by thermogravimetry (TG). The results show that, because of the barrier behavior of
exfoliated MMT layer, the temperature of thermal decomposition of PMMA/ MMT nanocomposites
is improved by about 10 °C, and thermal stability is improved by about double. The apparent
activation energy of decomposition, calculated by Ozawa equation, of nanocomposites is higher
than that of PMMA before 27 % mass loss.