bluuebunny/crossref_metadata_2025 huggingface dataset:
Deformation Behavior of Nitrogen Bearing Austenitic Steels with Various Nitrogen Contents
Authors: Kim Yong Suk , Nam Seung Man , Kim Sung Joon
Published: March 2009

Tensile deformation behavior of the high-nitrogen austenitic Fe-18Cr-14Mn-4Ni-3MoxN
steel with various nitrogen contents has been studied. The nitrogen content of the steel varied
from 0.28 to 0.88 wt. %. Nitrogen atoms in high nitrogen steel (HNS) make an interstitial solid
solution by being scattered in the steel constituting a short-range order. They strengthen the
austenite matrix without deteriorating ductility of the steel. The present investigation was carried
out to elucidate the hardening and plasticizing role of the nitrogen in the HNS by analyzing tensile
deformation behavior of the steel containing various nitrogen contents. Tensile tests of the steel
specimens were performed at room temperature with a constant strain rate of 5x10-5/sec.
Microstructure of the tested specimens was analyzed to explore the deformation mechanism of the
HNS as a function of nitrogen contents. The flow stress of the steel increased with the increase of
the nitrogen content; however, the specimen with the highest nitrogen content (0.88 wt. %) showed
saturated strength and reduced ductility. The superior mechanical property of the HNS was
explained by the low stacking fault energy and the twin-induced plasticity provoked by the nitrogen.
Hyperelastic Muscle Simulation
Authors: Ansari Mohd. Zahid , Lee Sang Kyo , Cho Chong Du
Published: March 2009

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and
nearly incompressible. The incompressible material behavior may lead to some difficulties in
numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations
can be used to overcome incompressible material problems. The hyperelastic materials can be used
to describe the biological skeletal muscle behavior. In this study, experiments are conducted to
obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal
muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A
commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior
of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can
be used to successfully simulate the muscle material behavior. Such an analysis can be used to
simulate and analyze other soft tissues that show similar behavior.
The Effect of CaO Addition on the Microstructural, Mechanical and Dielectric Properties of Pure MgO Ceramic
Authors: Sutjipto Agus Geter E.
Published: March 2009

High purity MgO is a common ceramic material used as a protecting layer in an
alternating current plasma display panel (AC-PDP). In this work, pure MgO was added by CaO for
a better protecting layer. The effect of CaO addition was discussed according to the changes in the
microstructure, mechanical strength and the ability of the sample to withstand surface breakdown
(flashover) with various CaO addition in the powder mixture. In addition, it was found that 2.5 wt%
CaO-addition shows a better electrical discharge. Since secondary electron emission coefficient
contributes in the electrical discharge, it could be predicted that the 2.5 wt% CaO added MgO has a
higher secondary electron emission constant and becomes a promising candidate for a protecting layer
in AC-PDP.
Coaxing Effect in Stainless Steels and High-Strength Steels
Authors: Nakajima Masaki , Jung Jae Woong , Uematsu Yoshihiko , Tokaji Keiro
Published: March 2009

The effects of prestrain and strength level on the coaxing behavior were studied in
austenitic stainless steels and high strength steels, respectively. The materials used were austenitic
stainless steels, SUS304 and SUS316, and high strength steels, SCM435, SNCM439 and SUJ2.
Stress incremental fatigue tests were performed using cantilever-type rotating bending fatigue
testing machines. It was found that the steels except for SUJ2 showed a marked coaxing effect.
Non-propagating cracks were not detected in all the steels examined. Based on hardness test, X-ray
diffraction measurement and EBSD analysis, it was indicated that the coaxing effect occurred due to
work hardening and strain-induced martensite transformation in austenitic stainless steels and to
strain-aging in high strength steels.
Fatigue Analysis of Multi-Lap Spot Welding of High Strength Steel by Quasi Static Tensile- Shear Test
Authors: Sin Su Rok , Yang Sung Mo , Yu Hyo Sun , Kim Chai Won , Kang Hee Yong
Published: March 2009

The welding quality of spot weldment is an important factor that significantly affects the
strength, stiffness, safety, and other performance characteristics of vehicles. Therefore, quality
control and fatigue life evaluation of spot weldment are necessary processes. This paper presents a
method for determining the fatigue life of multi-lap spot weldment of a high strength steel sheet. In
this method, the fatigue life is estimated by using the lethargy coefficient, which is the total defect
coefficient according to rupture stress and time obtained by the quasi static tensile-shear test. Also,
in this study, we modified the lethargy coefficient by using the welding current. And, we define a
specific lapping constant, which is a characteristic constant of 2 or 3 lap weldments. The fatigue life
obtained by the fatigue estimate equation, which contains a specific lapping constant was compared
and verified with an experimental value. And we analyzed the relation of lap number, welding
current and fatigue life. This method can save processing time and cost for predicting the life cycle
of a structure.
Crack Orientation Dependence for Fatigue Behavior of Titanium Single Crystals
Authors: Sakamoto Takahiro , Ando Shinji , Kitahara Hiromoto , Tsushida Masayuki , Tonda Hideki
Published: March 2009

In this present study, the fatigue behavior of titanium single crystals containing cracks
growing in different crystallographic orientations has been investigated. To investigate fatigue
fracture behavior of small single crystals, plain bending fatigue test method for thin sheet specimen
was developed. One end of the sheet specimen is fixed at a voice coil of the loudspeaker and the
other end is set free. A bending mode resonance occurs in the specimen due to forced vibration at
the fixed end.
In A-specimen, the notch plane and the direction are (11-20) and [1-100], respectively, the crack
propagated parallel to {1-100} plane and striation-like markings were observed on the fatigue
surfaces. In B-specimen with a notch of (1-100) and [11-20], the crack also propagated parallel to
{1-100} plane as similar to A-specimen. These cracks are deduced to extend by alternating shear on
two intersecting prismatic slip systems at the crack tip. In F-specimen with a notch of (0001) and
[11-20], the crack propagated parallel to (0001) and twins were observed near the crack. As a result,
S-N curves of each specimen showed strong orientation dependence and the fatigue strength of
F-specimen was the highest in these specimens.
Effect of Heat Treatment on the Creep Properties of Ti-22Al-27Nb/TiB Composite
Authors: Emura Satoshi , Hagiwara Masuo
Published: March 2009

A TiB particulate-reinforced Ti-22Al-27Nb (mol%) alloy, based on the orthorhombic
intermetallic phase, was prepared using gas atomization powder metallurgy method. In the
as-atomized condition, extremely fine TiB particulates of less than 1-μm diameter and 5-μm length
were dispersed in the matrix. After annealing heat treatment (heat treated at 1423 K with subsequent
furnace cooling), this composite exhibited a lamellar matrix microstructure and showed better creep
properties than a composite produced using conventional ingot metallurgy method, with coarse TiB
particulates of 5-μm diameter and 40-μm length. Coarsening of the matrix microstructure and
growth of TiB particulates occurred after annealing heat treatment at higher temperature (ca. 1473
K). Creep-resistance improvement was also observed, which seemed to be mainly attribute to the
effect of the matrix microstructure. From measurements of stress components and activation energy,
all composites showed an identical creep mechanism: dislocation-controlled creep.
An Evaluation of Thermal Fatigue Cracking and Chemical Reaction in Die Casting Mould
Authors: Youn Kuk Tae , Rhyim Young Mok , Lee Jong Hoon , Lee Chan Gyu , Jung Yun Chul
Published: March 2009

It is well known that the main failure mechanisms in die-casting mould are heat checking
due to thermal fatigue and melt-out caused by chemical reaction between die and molten alloys.
Thermal fatigue tests were carried out using the thermal cycle simulator to establish the proper
method to estimate the thermal fatigue resistance of hot die steel. In this study, the thermal shock
tester consisted of induction heating and water spray cooling unit was constructed to evaluate
thermal crack propagation resistance and the sum of crack length per unit specimen length, Lm is
proposed as the index representing the susceptibility to crack initiation and propagation. Also, new
concept of measurement for the melt-out behavior was suggested. AISI H13 hot work tool steel was
solution treated and tempered at various temperatures, to control the hardness and toughness that
have effect on the behavior of thermal crack propagation. The result of thermal fatigue test showed
that there is optimum value of hardness and impact energy to maximize the thermal crack
propagation resistance. The influence of nitriding on melt-out resistance was also investigated. The
dissolution rate due to melt-out phenomenon tended to be smaller for thicker compound layer.
Furthermore, the resistance to melt-out was affected by the compound layer thickness rather than
that of diffusion layer. The results of the both tests properly reflect the effect of materials properties
on failure modes of die-casting mould and it means those test methods are suitable to evaluate the
durability of hot work tool steel for die-casting.
Effect of Size for Micro-Scale Dimples on Surface under Lubricated Sliding Contact
Authors: Chae Young Hun
Published: March 2009

The current study investigated the effect of micro-dimple size on reduction friction to
understand the potential of friction reduction through micro-scale dimple to fabricate by
photolithography on pin-on-disk test using flat-on-flat contact geometry. It was verified that the
friction property with respect to the same pitch influences the size of dimple under lubricated sliding
contact. Additionally, it was recognized from Stribeck curve that the friction property has a
connection with the size of dimple. This can explain the relationship between the friction coefficient
and a dimensionless parameter for lubrication condition. The friction property has an effect on the
size of surface texture on reduction friction, not only because of the density of dimple, but also
because of the ratio of diameter/pitch. A ratio of approximately 0.5 is recommended under the tested
friction condition. It is suggested that the ratio of d/p is an important parameter for surface texture
design.
Investigation of the Oxide Ion Conduction Mechanism in LaGaO3-Based Electrolytes through High-Temperature Neutron Powder Diffraction
Authors: Kajitani Masahiro , Matsuda Motohide , Hoshikawa Akinori , Kamiyama Takashi , Izumi Fujio , Miyake Michihiro
Published: March 2009

The crystal structure and oxide ion conduction properties of La0.9Sr0.1Ga0.9Mg0.1O2.9 were compared
with those of LaGa0.8Mg0.2O2.9 with the same oxygen vacancy concentration. Although
La0.9Sr0.1Ga0.9Mg0.1O2.9 had a smaller free space through which oxide ions pass compared to
LaGa0.8Mg0.2O2.9, the activation energy of oxide ion conduction in the former was lower. This was
attributed to the large displacement of La and Ga in La0.9Sr0.1Ga0.9Mg0.1O2.9. The GaO6 octahedral
tilts in the LaGaO3 perovskite structure were reduced by double doping with Sr and Mg.
Reduction of the GaO6 octahedral tilt proved effective for oxide ion conduction.
Preparation of TiO2 Thin Films by Electrophoresis Deposition Method for Dye-Sensitized Solar Cells
Authors: Yamamoto Kunio , Sakai Kenji , Yoshikado Shinzo
Published: March 2009

The purpose of this study is to prepare high-quality TiO2 thin films for dye-sensitized solar cells
using the electrophoresis method. A high-quality TiO2 thin film has a thickness of approximately 10
μm and no crack on the surface. In this study, TiO2 thin films were deposited by changing the
configuration of electrophoresis electrodes. When electrodes were set parallel to horizontal and ITO
glass substrate was set in the upper electrode, an excellent TiO2 thin film of approximately 10 μm
thickness was obtained by depositing very thin TiO2 films as a buffer layer. The new film has the
highest open-circuit voltage and short-circuit current density.
Study on Recovery of Electrical Degradation of ZnO Varistors
Authors: Yoshida Hiroshi , Takada Masayuki , Yoshikado Shinzo
Published: March 2009

The relationship between the crystal structure of Bi2O3 and the recovery of the electrical
degradation of ZnO varistors was investigated. The evaluation methods used were analysis of the
voltage-current (V-I) characteristics, scanning electron microscopy (SEM), energy-dispersion X-ray
spectroscopy (EDX), and X-ray diffraction (XRD) measurements. The electrical degradation was
estimated by the nonlinearity of the V-I characteristics. A marked recovery of the nonlinearity of the
V-I characteristics was observed for a sample having the crystal structure of δ-type Bi2O3. It is
speculated that the electrical degradation is markedly recovered for optimum conditions of both the
amount and the crystal structure of the added Bi2O3, because, for samples sintered for a long time,
the recovery speed is shorter than that for samples sintered for a shorter time. During long-time
sintering, the amount of Bi2O3 decreased because of evaporation. No change of the crystal structure
of Bi2O3 was observed upon repeated the electrical degradation and the recovery. It is suggested that
another mechanism apart from the diffusion of oxygen ions through the grain boundaries of ZnO
particles contributes to the electrical degradation and recovery of the nonlinearity of V-I
characteristics.
High Frequency Dielectric Permittivity Measurement of Dielectric Layer of MLCC Using Non-Contact Probe
Authors: Kakemoto Hirofumi , Li Jianyong , Harigai Takakiyo , Nam Song Min , Wada Satoshi , Tsurumi Takaaki
Published: March 2009

Direct observations for high frequency microscopic dielectric distributions in cross sections of a multi-layer
ceramic capacitor were carried out using non-contact type microwave probe. The measured data were imaged
from the raw data and rounding data process. Using microwave reflection intensity mappings from cross sections
of multi-layer ceramic capacitor, the dielectric permittivity distribution in micro-region of a multi-layer ceramic
capacitor was measured at room temperature. The spatial resolution was experimentally estimated to be about 10
μm from mappings of the dielectric and inner electrode layers in a multi-layer ceramic capacitor.
The Characteristics of Fine-Sized LiMn(12-X)/6Alx/6O4(0.05≤x≤2) Powders Prepared by Spray Pyrolysis
Authors: Ju Seo Hee , Kim Do Youp , Koo Hye Young , Hong Seung Kwon , Jo Eun Byul , Kang Yun Chan
Published: March 2009

The series of partially Al-substituted lithium manganese oxides were prepared by spray pyrolysis
process from spray solutions with citric acid and ethylene glycol. The as-prepared particles obtained
from spray solution with citric acid and ethylene glycol turned to fine-sized LiMn(12-
x)/6Alx/6O4(0.05≤x≤2) particles with regular morphology after post-annealing. The discharge
capacities of the particles post-annealed at temperature of 800oC changed from 128 to 84 mAh/g
when the x of the LiMn(12-x)/6Alx/6O4 particles was changed from 0 to 2. The Al-doped LiMn2O4 fine
particles prepared by spray pyrolysis from spray solution with citric acid and ethylene glycol had
good cycle properties.
In Situ Synthesis of TiB2/Mg Composites by Flux-Assisted Synthesis Reaction of the Al-Ti-B System in Molten Magnesium
Authors: Cao Wei , Zhang Cong Fa , Fan Tong Xiang , Zhang Di
Published: March 2009

TiB2 particulate reinforced magnesium matrix composites were successfully fabricated by adding a TiB2–Al master alloy processed via the flux-assisted synthesis (FAS) reaction into molten magnesium. X-ray diffraction (XRD) analysis and microstructural characterization of the TiB2–Al master alloy revealed the formation and uniform distribution of TiB2 reinforcements. By stirring, magnesium matrix composites with dispersed homogenously TiB2 particles can be obtained. Microstructural characterization of the TiB2/Mg composites revealed retention of hexagonal or rectangular TiB2 particulates with the size of about 1 μm.
Microstructure and Tensile Properties of In Situ Synthesized (TiB+TiC)/Ti-6Al-4V Composites
Authors: Lu Jun Qiang , Lu Wei Jie , Liu Yang , Qin Ji Ning , Zhang Di
Published: March 2009

In this paper, Ti-6Al-4V matrix composites reinforced with 5% or 10% TiB and TiC were in situ synthesized by common casting and hot-forging technology utilizing the reaction between titanium and B4C. The phase constituents were identified by XRD while transus temperatures were determined by DSC and metallography. The evolution of microstructures was studied by optical microscopy. The effects of reinforcements on the microstructures, tensile properties and fractures at room temperature were discussed. The results show that yield strength and ultimate tensile strength increased significantly while ductility decreased with reinforcements increasing. Fracture type turned to brittle when reinforcements increased.
Comparison of Activated Carbon from Water Bamboo Residues with Surfaces Modified by Different Methods
Authors: Huang Da Cheng , Fan Tong Xiang , Zhang Di
Published: March 2009

Surface modification of activated carbon was performed using such chemical methods as
nitric acid and H2O2.Oxidation of the ACs made samples with weakly acidic functional groups and
the presence of other groups was confirmed by Fourier transform infra red (FTIR) spectroscopy. With
different time for modification, the amount of elements of carbon and oxygen will change a lot and
the results of these experiments show a stronger ability of HNO3 solution in oxidization. Furthermore
the differences of face morphology between ACs and oxidized ACs can be observed clearly
The Thinking on Multiphase Materials
Authors: Guo Jing Kun , Kou Hua Min , Pan Yu Bai
Published: March 2009

The main problems for multiphase materials are the even mixing and the bonding or reacting among two or more phases, as well as the states of their grain boundaries. The mixing of two phases is usually effective by using liquid medium. The technology of second phase coating for the original particles or so call nucleo-shell structure is a well approach for the even mixing. For ceramic matrix multiphase materials low sintering temperature is the effective way to avoid the occurring of reaction between different phases. The design of grain boundary and its stress is important for their bonding states. The thinking for above problems would be described briefly in this paper. The purpose of multiphase materials design is expected that every phase will be playing its role, combining together and then given out a comprehensive performances. So it is necessary to consider the following problems. 1. Even mixing Even mixing between each other material is important for multiphase materials. It’s the better when the processing is carrying on in the liquid state for the even mixing of two phase materials. Using physical or chemical method could be formed the fine solid particles with even dispersion of two or more phases materials. Usually it could be obtained nano-scale particles. The application of nano-technology is necessary. The nano-scale mixing of two phases materials would be greatly increased the contacting surface of each other particles without agglomeration. Of course, if one phase of material is fine solid particle which disperses in another phase of material solution, the even mixing of two phases is obtained similarly. Making a coating to other phase particle is a very good approach for the two phases even mixing. Coating process is attracting more and more attention in the preparation of composite materials mainly due to its predominance in the improvement of the uniformity for different phases [1]. The thickness of coating material determines the amount proportion of two phases which is able to be control. Two examples of so-called “nucleo-shell structure” will be introduced in the following parts. Cermet composites have been widely studied due to their potential for achieving higher toughness and reasonable strength compared with ceramic matrix. But except for numbered systems, such as Co/WC and Ni/TiN, few systems have reached the people’s expectation mainly for the poor wettability between metal and ceramic. Al/Al2O3 cermet is a low density and high strength material, and it has many potential and actual applications in military, industrial and consumer regions. To improve the dispersive uniformity of the two phases, coating aluminum with alumina may be a good candidate since such coatings not only stabilize aluminum dispersions but also make it possible to control inter-particle and particle-matrix interactions [2]. Figure1a-c shows the images
The Mechanical Properties of a New Titanium Alloys with Low Modulus
Authors: Wang Hong Hua , Rong Chen , Zhang Di
Published: March 2009

We developed a new titanium alloy with high strength, low elastic modulus, high elasticity and
plasticity after cold working. Thermo mechanical processing, ageing, recrystallization after cold working was
conducted to change the mechanical properties. The release of the elastic deformation energy after cold
working is help to get the low modulus, however, the precipitation of α phase hamper the formation and
propagation of the fatigue crack. Recrystallization after cold working could refine the grain size from 100μm to
1～5μm. Cold working after recrystallization absolutely restricts the propagation of the fatigue crack. As a
result, the fatigue strength was increased, and the same time, it keeps the low elastic modulus.
Microstructure Evolution and Microwave Dielectric Properties of Multi-Phase Ba(Ti1-xMx)O3 Ceramics
Authors: Wang Sea Fue , Wang Yuh Ruey , Yang Thomas C.K.
Published: March 2009

In this study, the feasibility for use of multiphase BaTiO3 ceramics as microwave
dielectric resonators was evaluated through the substitution of metal ions in B sites, such as ions of
Mn, Co, Mg, In, Fe, Zn, and Ni. The effects of metal ions substitution and sintering conditions on
the densification, microstructural evolution and microwave properties of the BaTiO3 ceramics
containing cubic and hexagonal phase were examined.
Characterization on Microstructure Homogeneity of θ-Al2O3 Powder Systems During Phase Transformation
Authors: Yen Fu Su , Chang Pei Ling , Yu Pei Ching , Yang Rong Jeh
Published: March 2009

The traditional differential thermal analysis (DTA) techniques are employed to evaluate the kinetic behavior induced by the inter-particle relationships in a nano-particle θ-Al2O3 powder system during θ- to α- phase transformation. Discrepancies in homogeneity and inter-particle distance of the powder system may result in the diagnostic DTA profiles which can be use to evaluate the characteristics of the powder system as well as the formed α-Al2O3 particles. Based on the acknowledgement, a quasi-homogeneous transformation shows that a duration of 90 seconds is needed for one θ-crystallite to transform into one α-nucleus with a heating rate of 10 oC min-1 and fabrication of the high phase-pure and mono-sized α-Al2O3 powders is obtained.
Effect of Wolastonite Mineral (CaO SiO2) Content in Continuous Casting Powder to SEN Erosion
Authors: Dević Snezana , Carli R.
Published: March 2009

The basic idea of the work was to analyze the effect of the wollastonite mineral CaO
SiO2 content in the continuous casting powder related to the SEN erosion. In order to realize the
research, experiments were conducted in the laboratory conditions. The research, experiment, was
realized in the Magnohrom Kraljevo laboratory, and cryptonym furnace EV16 was used for
refractory material behavior. Cut SEN pieces from the slag zone in the reduction atmosphere were
treated in the furnace with three types of casting powder of different mixtures ratio of SRD1
(without wollastonite) and SRD2 (with wollastonite): Casting powder 1 - SRD1/SRD2 = 50/50 %,
Casting powder 2 - SRD1/SRD2 = 25/75 % and Casting powder 3 - SRD1/SRD2 = 75/25 %.
Temperature of the experiment was in the range of 15200C – 15400C, and treatment time was
changed simulating the average casting time of the heat; one heat (45 min), two heats (90 min), and
three heats (135 min). The experiment pointed out that the erosion of the SEN was reduced with the
increased ratio of wollastonite in the casting powder. The erosion rate of the SEN exposed to the
casting powder 2 in the laboratory conditions was 0.0055 mm/min, whilst the erosion rate of the
SEN exposed to the casting powder 3 (with the least wollastonite content) was 0.0075 mm/min.
Erosion rate of SEN exposed to the casting powder 2 was lower for the 26.27 % related to the
casting powder 3, and 17.90% lower than the erosion rate of the casting powder 1 (the erosion rate
of the casting powder 1 was 0.0067 mm/min). These laboratory experiments are very consistent
with results obtained in the plant conditions [1,2,3]. At that time, results indicated that SRD1
casting powder without wollastonite has the erosion rate 46 % higher than SRD2 casting powder
with wollastonite. On the basis of the laboratory researches and earlier plant conditions researches it
could be concluded that wollastonite mineral content in the casting powders has significant effect
on the SEN erosion, in the way that the SEN erosion rate was decreased with the increased
wollastonite content in the casting powders.
Preparation and Properties of Spark Plasma Sintered AlN/BN Nano-Composites
Authors: Li Mei Juan , Zhang Lian Meng , Wei Z.D. , Shen Qiang , Zhang Dong Ming
Published: March 2009

Nano-sized turbostritic-BN (t-BN) was fabricated through chemical process using boric acid and urea in this work. By the same method, the AlN powders coated with nano-BN were prepared too. The results of X-ray diffraction (XRD) and transmission electron microscope (TEM) revealed that nano-sized t-BN was synthesized at about 600°C in nitrogen gas and it surrounded the surface of AlN particles. High-density AlN/BN nano-composites were fabricated spark plasma sintering (SPS). Microstructure and properties of AlN/BN nano-composites (5~30vol% BN) were investigated. The h-BN flake particles were homogenously dispersed at AlN grain boundaries and within grains in the AlN/BN composites. A little nano-BN additions significantly improved the bending strength of the nano-composites. However, the bending strength was decreased with the BN content increasing. The thermal conductivity of AlN/BN nano-composites was investigated too.
Evaluation of Damage for Alumina/Graphite Refractory Using Apparent Sonic Velocity Measurement
Authors: Furushima Ryoichi , Matsuo Yohtaro , Shiota Tadashi , Yasuda Kouichi
Published: March 2009

Damage evaluation for alumina/graphite refractory was conducted under uni-axial compressive
loading. Apparent sonic velocity during a loading-unloading cycle was measured by ultrasonic
method. Quasi-elastic-plastic behavior was observed in the stress-strain curve for each cycle.
However, it is difficult to detect damage from the stress-strain curve during each loading- unloading
cycle. On the other hand, using the result of change in apparent sonic velocity during a
loading-unloading cycle, it is possible to estimate damage to some extent. The apparent sonic velocity
kept approximately constant during the first loading process, but it decreased remarkably during the
first unloading one. In the subsequent loading-unloading cycles, it increased in the loading process
and decreased in the unloading one. Consequently, it is concluded that damage mechanism during the
first loading-unloading cycle is different from that during the subsequent loading- unloading cycles
for alumina/graphite refractory.
Influence of Crack Healing on Mechanical Properties of SiC Fabric / SiC- Al2O3 Matrix Laminates
Authors: Arima Takashi , Hirata Yoshihiro , Matsunaga Naoki , Shibuya Masaki
Published: March 2009

SiC fabric including SiC (60 vol%)-Al2O3 (40 vol%) mixed powders and SiC (60
vol%)-Al2O3 (40 vol%) sheet of 60 μm thick were alternatively laminated and hot-pressed to 79 -
83 % of theoretical density under a pressure of 39 MPa in an Ar atmosphere at 1600 °C. Four cracks
were formed on the polished laminates with 30 ± 3 and 43 ± 2 vol% SiC fabric along the center line
perpendicular to the direction of length by Vickers indentor at the load of 98 N and healed in air at
1100 °C for 24 h. The strength (253 MPa) of the as-hot-pressed laminate without SiC fabric
decreased to 119 MPa after the introduction of the cracks but was recovered to 336 MPa after the
healing. The crack size decreased because of the oxidation of SiC particles during the healing.
However, the laminates with SiC fabric had a high damage tolerance and gave no change in the
strength (~100 MPa) after the introduction of the cracks. The SiC fabric prevented the propagation
of the cracks. After the healing, the porosity of the laminates decreased owing to the volume
increase during the oxidation of SiC particles and SiC fabric. The strength of the healed laminates
was comparable to that of as-hot-pressed laminates.
Solution Growth of Single Crystalline 6H-SiC from Si-Ti-C Ternary Solution
Authors: Suzuki Kenji , Kusunoki Kazuhiko , Yashiro Nobuyoshi , Okada Nobuhiro , Kamei Kazuhito , Yauchi Akihiro
Published: March 2009

Solution growth of 6H-SiC single crystal from Si-Ti-C ternary solution using the
accelerated crucible rotation technique (ACRT) was performed. The SiC growth rate exceeding 200
μm/hr was achieved in several ACRT conditions. Such a high growth rate can be ascribed to the
enhancement of the carbon transport from the graphite crucible to the growth interface due to the
use of the ACRT. The incorporation of inclusions of Si-Ti solvent in the grown SiC crystal was also
significantly suppressed by using the ACRT. The intensive convection near the growth interface
induced by the ACRT resulted in not only the marked increase of SiC growth rate but also the
superior homogeneity in the surface morphology. It was concluded that faster stable growth could
be accomplished in the SiC solution growth using the ACRT. The obtained SiC self-standing crystal
exhibited homogeneous green colour without cracks and inclusions. We investigated the crystalline
quality of the grown SiC crystal by means of X-ray diffraction. The, ω-scan rocking curves of
(0006) reflection measured by X-ray diffraction provided the FWHM of 15-20 arc-second showing
the excellent crystallinity of the solution grown 6H-SiC single crystal.
Wavelet-Based Modal Parameter Identification through Measurements for Damage Detection
Authors: Chen Y.B. , Han J.G. , Yang D.Q.
Published: March 2009

Structural operating conditions may significantly differ from those applied during
laboratory tests where the structure is well known, well installed and properly excited. For structures
under their natural loading conditions, or excited by random forces, excitations cannot be measured
and are usually non stationary. Hence, an improvement operational modal analysis is a useful
complement to the traditional modal analysis approach. The aim of this paper is to present the
application of a new identification procedure, named wavelet-based identification technique of
structural modal parameters. Wavelet-based identification that works in time-frequency domain is
used to identify the dynamic characteristics of the structural system in terms of natural frequencies,
damping coefficients and mode shapes. The paper has shown how the amplitude and the phase of the
wavelet transform of operational vibration measurements are related to eigenfrequencies and
damping coefficients, and the wavelet-based spectrum analysis is used to identify the mode shapes of
the structure. Those modal parameters can be used to detect damage of structures. A simulation
example has demonstrated that current identified results are comparable with those previously
obtained from the peak pick method in frequency domain and stochastic subspace identification in
time domain.
An Experimental Investigation on Composites Through-The-Thickness Stitched Foam Core Sandwich Panels
Authors: Sun Qin , Zheng Xi Tao , Li Ye , Chai Ya Nan , Cao Zheng Hua
Published: March 2009

This study explored the feasibility and potential benefits provided by the addition of
through-the-thickness reinforcement to foam core sandwich structures. Through-the-thickness
stitching is proposed to increase the interlaminar strength and damage tolerance of composite
sandwich structures. A low-cost, out-of-autoclave processing method was developed to produce
composite sandwich panels with carbon fiber face sheets, a closed-cell foam core, and
through-the-thickness Kevlar stitching. The sandwich panels were stitched in a dry preform state,
vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Molding (VARTM)
processing. For comparison purposes, unstitched sandwich panels were produced using the same
materials and manufacturing methodology. Five types of mechanical tests were performed: flexural
testing, flatwise tensile and compression testing, core shear testing, and edgewise compression
testing. Drop-weight impact testing followed by specimen sectioning was performed to characterize
the damage resistance of stitched sandwich panels. Compression after impact (CAI) testing was
performed to evaluate the damage tolerance of the sandwich panels. Results show significant
increases in the flexural stiffness and strength, out-of-plane tensile strength, core shear strength,
edgewise compression strength, and compression-after-impact strength of stitched sandwich
structures.
DRX in 7050 Aluminum Alloy during Constraint Deformation Processing at High Temperature
Authors: Zhen Liang , Hu W.H. , Shao Wen Zhu , Chen J.Z. , Zhang Xin Mei , Zhang Bao You
Published: March 2009

Combined extrusion experiment (including direct and indirect extrusion) at 440 for
large amount of deformation was carried out with the solution treated AA7050 aluminum alloy.
Qualitative description and quantitative characterization were conducted employing electron
backscattered diffraction (EBSD) technique on the microstructure of typical regions with different
filler contents. These characteristic regions were filled at the following stages: ahead of filling (AF),
beginning of filling (BF), mid stage of filling (MF) and the end of filling (EF). EBSD results
showed that recrystallization fraction during direct extrusion were 8.3%, 13.5%, 9.3% and 11.2%,
for AF, BF, MF and EF, respectively. Recrystallization fraction during indirect extrusion were
15.5%, 9.1% 5.2% and 9.9%，for AF, BF, MF and EF, respectively. It shows that the mode and the
amount of deformation played an important role in DRX. DRX grains were formed continuously
during direct extrusion, while during indirect extrusion, fewer DRX grains generated, and only
originally generated DRX grains grew larger gradually.
High Temperature Deformation Mechanism of 7075 Aluminum Alloy
Authors: Zhu Dan Yang , Zhen Liang , Lin Chen , Shao Wen Zhu
Published: March 2009

This paper presents the high temperature deformation behavior of 7075 aluminum alloy
after T6 heat treatment by using electron tensile test machine with a temperature range of 230 - 440 °C,
strain rate of 0.01 s-1, deformation of 50 % and 100 %, respectively. The morphology of the fractured
surfaces, dislocation and change of sub-grains before and after the tensile test were investigated by
using scanning electron microscope (SEM) and electron back scattering diffraction (EBSD) technique.
The results show that the fracture mechanism of 7075 aluminum alloy was ductile rupture. The
thermal deformation of the 7075 aluminum alloy showed the steady-state flow characteristics, and the
flow stress decreased with the increase of deformation temperature. Orientation angle offset of the
grain boundary decreased with the increasing of the deformation at 440 °C, indicating that the
continuous dynamic recrystallization occurred inside the 7075 aluminum alloy.
Numerical Simulation on Cracks Propagation and Coalescence Process in Rock
Authors: Qiao Deng Pan , Sun Ya Ning , Wang Shu Hong , Zhang Juan Xia
Published: March 2009

The failure of rock mass under loading is resulting from preexisting flaws, such as cracks,
pores and other defects. However, the propagation and coalescence mechanism among multi-group
cracks is still a puzzle, especially to the engineering rocks in site. In this study, the failure of rock
samples with two groups of preexisting parallel cracks under the axial load were numerically
investigated by the Rock Failure Process Analysis code (RFPA) from a mechanics point of view. The
simulated results reproduce the rock failure process: at the first loading stage, the particle is stressed
and energy is stored as elastic strain energy with a few randomly isolated fractures. As the load
increases, the isolated fractures are localized to form a macroscopic crack. At the peak load, the
isolated fractures unstably propagate in a direction parallel to the loading direction following tortuous
paths and with numerous crack branches. Finally, the major crack passes through the rock sample and
several coarse progeny cracks are formed. Moreover, in the vicinity of the contacting zone the local
crushing is always induced to cause fines. On the base of the simulated results, it is found that the
dominant breakage mechanisms are catastrophic splitting and progressive crushing. It is pointed out
that the particle breakage behavior strongly depends on the heterogeneous material property, the
irregular shape and size, and the various loading conditions. Because of heterogeneity, the crack
propagates in tortuous path and crack branching becomes a usual phenomenon. The failure process of
rock sample demonstrated that due to the high stress concentration at the cracks tip or some weaker
strength elements which are not on the cracks surface initiate some micro-fractures, those cracks and
fractures may gradually become larger and larger, more and more with the progress of loading so that
join into the branch cracks leading to the rock failure in the end. Not only did the output of the
numerical simulation study compare well with the experiment results, but also the further insights of
the mechanism of cracks propagation and coalescence process in rock mass were obtained.
Research on Grind-Hardening Temperature and Cooling Rate of 48MnV Microalloyed Steel
Authors: Xiao Bing , Su Hong Hua , Li Shu Sheng , Xu Hong Jun
Published: March 2009

The temperature, time and cooling rate are key factors in the hardening process using the grinding heat instead of the high frequency induction heat source. Thus, this paper established the mathematical model estimating the grind-hardening temperature, experimentally determined the grinding temperature and the cooling rate of different grinding parameters for 48MnV microalloyed steel using the conventional aluminum grinding wheel on a surface grinder, and investigated the grind-hardening effects and the forming mechanism of grind-hardening layer. The results show that the estimating temperatures are comparatively close to the measuring ones and hence the model could be utilized to optimize the processing parameters, and the satisfactory grind-hardening temperature and cooling rate could be achieved under the optimized processing parameters. The microstructure of the grind-hardening layer, the fine needlelike martensite in the entirely hardened zone, the martensite and ferrite in the transitional region is similar to that acquired through the high frequency induction technique. Especially, the average hardness of the entirely hardened zone is 740HV and the depth of the hardened layer is adjacent to 1.5mm, which indicate that the grind-hardening effects are very excellent. Different from the forming mechanism of the high frequency induction hardened layer, higher grind-hardening temperature is needed to compensate shorter time austenitization, and because of thermo-mechanical loading induced during grinding, from surface to inside, the morphology of martensite changes from fine to thicker, then to finer, other than from thick to finer.
Parameters Optimization on the Lapping Process of 9Cr18 with Taguchi Method
Authors: Zheng Xiao Feng , Yuan Ju Long , Wen Dong Hui , Lou Fei Yan
Published: March 2009

9Cr18 is a type of martensite stainless steel. It has high hardness, chemical stability, fine
anticorrosion, wearable and quench stability. It has been used in different areas with
high-anticorrosion and high polishing surface as mirror. So it requires for the high level surface
quality after lapping and polishing. In this paper, the surface quality (surface roughness and flatness)
of 9Cr18 is discussed with lapping parameters which include velocity, load and time distribution of
two lapping steps(rough lapping and Ultra-precision lapping). In order to optimize those parameters,
an optimization experiment for lapping 9Cr18 with Al2O3 was designed by Taguchi method. Finally,
the optimum condition of each factor can be determined that speed: 80rpm, load:3.0kPa, and time
distribution: rough lapping time=15min, Ultra-precision lapping time＝45min are the optimum
conditions for both Ra and Wt.
The Experiment Method of the Study on the Airflow Field around the Grinding Wheel in Super-High Speed Based on PIV
Authors: Gong Ya Dong , Li Hu , Zhang Yan Cheng , Cai Guang Qi , Deng Zhao Hui
Published: March 2009

The investigation of the experiment method on airflow field around super-high grinding wheel by PIV (Particle Image of Velocity, PIV) instrument was introduced in the paper. The measure system and scheme were designed for the experiment with PIV applied in the super-high speed grinding wheel for the airflow. The processing method of experimental data was discussed and the experiment result validated the feasibility of the experiment method.
An Optimal Feed Interpolation with Jerk-Limited Acceleration for Five-Axis Grinding
Authors: Feng Jing Chun , Li Yu Hao , Wang Yu Han , Chen Ming
Published: March 2009

To overcome the acceleration discontinuity and feed fluctuation of the conventional
five-axis grinding interpolator, a jerk-limited acceleration is utilized and two aspects of constraints is
taken into account: (1) the machining dynamics, including the constraints of power, velocity,
acceleration and jerk represented by upper bounds for each axis (2) the contour constraints of linear
segments, including the linear distance of the segment and sharp corner at the segment junctions.
With the analysis of these constrains, the optimal feed for each segment and the joint feed at the
segment junctions is derived. The corresponding adjusted interpolation algorithm with jerk-limited
acceleration is presented such that a smooth motion during the machining can be maintained. The
presented algorithm is demonstrated by the simulation result.
Study on Squeeze Oil Film Damper in Ultrahigh Speed Grinding
Authors: Yu Tian Biao , Gong Ya Dong , Zhao Hai Feng , Liang Shuang , Wang Wan Shan
Published: March 2009

The operation principle of SFD and the center moving orbit of grinding wheel spindle
which under the operation of SFD are studied. Based on the theoretical research, the experiment is
studied and analyzed. The study results show that the application of SFD technology can effectively
restrain vibration which is caused by the imbalance quality when the grinding wheel spindle turning
at ultrahigh speed. And it can remarkably improve the working quality and work efficiency of ultra
high-speed grinder.
Study on the Surface Integrity of Polished Diamond Thick Film Prepared by EACVD
Authors: Xu Feng , Zuo Dun Wen , Chen Rong Fa , Lu Wen Zhuang , Wang Min
Published: March 2009

Chemical vapor deposited (CVD) diamond film is a good materials for cutting tools as its
a series of excellent properties. But because of its polycrystalline morphology, CVD diamond thick
film has a rough surface that limits its application in engineering. In this paper, study was carried
out on the mechanical lapping of diamond film. It is shown that surface roughness of the film was
reduced from Ra 4.5μm to Ra 0.2μm after 50-minute polishing. The surface integrity of polished
diamond thick film was investigated, which includes surface roughness, morphology and residual
stress. There are a lot of micro defects such as grooves, gas cavities and micro cracks on the
polished surface, which are the intrinsic defects generated in the deposition process of CVD
diamond film. The tensile stress of the film reduced through polishing as the release of the
deformation energy stored in the film.
Injection of Thermoplastic Polyurethane to Fix Diamond Beads on Wire Saws
Authors: Guo Hua , Wu Xiao Song , Zhang Yan Jun , Chen Yi Xin , Xu Xi Peng
Published: March 2009

An investigation was reported of the injection of thermoplastic polyurethane (TPU) to fix diamond beads on wire saws. Effects of injection material hardness, injection temperature and dwell pressure on the mechanical properties of three types of TPU plastics were studied and the results showed that with the increase of material hardness, both the 100% Modulus and the tensile strength of TPU were improved, but the rupture extensibility reduced. With the increase of injection temperature, the tensile strength increased but the rupture elongation decreased. To every type of TPU, a minimum injection temperature can be found for an ideal density of TPU.
Experiment on Dynamics of the Hybrid Polishing Kinematics Machine Tool with Clearance Based on the Flexible Multi-Body Systems
Authors: Yu Miao , Zhang Yuan Ming
Published: March 2009

This paper develops a novel five DOF hybrid polishing kinematics machine tool in order
to obtain more stable machining result in the elastic polishing on the free-form surfaces. Because
the machine tool is a complex multi-body system that comprises many close-loop structures,
jointing clearance becomes the important influence factor to its moving stability. The unified rigid
multi-body and flexible multi-body dynamics equation of for the parallel mechanism of hybrid
polishing kinematics machine tool is respectively built, which considers the influence of joint with
clearance and applies the kinematics model of Newton second state. The result of analysis shows
that the moving stability of the hybrid polishing kinematics machine tool is reduced due to the
existing jointing clearance. However, the interior flexibility of the mechanism can reduce the shock
effect of collision in the part of motion pair. It can improve the working stability of mechanism.
The Experimental Study of Phase Transformation Heat─Transfer in Simulation of Grinding of Ti Alloy
Authors: Ren Jia Long , Li Wei , Hang Hua , Guan Xiao Yan
Published: March 2009

Enhancing the cooling to spread heat in the process of the material cutting and milling
has positive effect on increasing the efficiency of cutting and milling and assuring the apparent
mass of test sample cut and milled. Basing on the experiment about the mixture of fixed pressure,
fixed air and different quantity of water atomizing jet cooling the Ti alloy, this article discusses
performance and regulation of phase transformation heat—transfer of simulating grinding Ti alloy
forced air cooling by the mixture of fixed pressure, fixed air and little water.