bluuebunny/crossref_metadata_2025 huggingface dataset:
Compressive Strength and Phase Transformation of Zirconia Porous Ceramics at Different Sintering Temperatures
Authors: Chen Chang Lian , Shen Qiang , Li Jun Guo , Zhang Lian Meng
Published: March 2009

A series of zirconia porous ceramics with different density are fabricated with commercial
zirconia powder and zirconia hollow balls by pressureless sintering technology. The microstructure
and phase transformation are characterized respectively by SEM and XRD testing methods. The
result indicates that the density and compressive strength depend greatly on zirconia powder content
at the same sintering temperature, and elevating sintering temperature just has a little effect on the
density and compressive strength for the samples of the same zirconia powder content. The XRD
diffraction patterns analysis shows that elevating sintering temperature is helpful to eliminate
monoclinic zirconia and the best sintering temperature should be beyond 1700°C.
Improvement of Oxidation Resistance of Graphite Powder Treated with Phosphate
Authors: Yoshida Katsumi , Hyuga Hideki , Kondo Naoki , Kita Hideki
Published: March 2009

Graphite powder was treated with lanthanum, aluminum and magnesium phosphate
solution, and oxidation resistance of the obtained graphite powder was evaluated. Oxidation starting
temperature and oxidation completion temperature of graphite powder treated with various
phosphates were 50-100oC higher than those of as-received graphite powder. Graphite powder
treated with small amount of lanthanum phosphate exhibited the higher oxidation starting
temperature than graphite powder treated with aluminum and magnesium phosphates. LaP5O14
would partially exited on graphite powder, and protect the edge carbon atoms of graphite and reduce
the reactivity of carbon atoms toward oxygen, resulting in improving the oxidation resistance.
The Effect of SiAlON Precursor Nanostructurization in a Planetary Mill on the Properties of Sintered Ceramics
Authors: Sopicka-Lizer Malgorzata , Pawlik Tomasz , Włodek Tomasz , Tańcula Marta , Chernik Galina
Published: March 2009

The results on the effect of nanostructured β-sialon precursor on the sintering and properties of the resultant ceramics are presented. The standard mixture of β-sialon precursor with 0.4z substitution degree was activated for 30 min in a planetary mill with an acceleration of 28g. Activation in the planetary mill resulted in diminution of the crystallite size and significant imperfection of the crystal lattice of the powder particles. The sintering experiments were performed at 1450-1600 °C in a powder bed. The relative density of the sintered bodies achieved the value of 97 %. The nanostructured material was produced after pressureless sintering at 1500 °C. It is concluded that high activation degree of the powders is necessary to obtain fully dense ceramics.
Evaluation of Thermoelectric Properties of Highly Dense Bi2Te3 Nanowire Arrays by Macro-Integration Method
Authors: Wang Chun Fen , Wang Qun , Liufu Sheng Cong , Yao Qin , Chen Li Dong
Published: March 2009

High dense Bi2Te3 nanowire arrays were fabricated in porous anodic alumina (PAA) by
electrochemical deposition. A macro-integration measurement was used to study the thermoelectric
properties of a superimposed layer of Bi2Te3/PAA structure. In this macro-integration system,
meaningful amounts of heat will transport along Bi2Te3 nanowire arrays, and so the measurement
errors of micro-current and micro-temperature difference of individual nanowire can be eliminated.
The influences of wire diameter, area fraction of wires and interface thermal resistance in the
sandwich structure on the measurement accuracy of Seebeck coefficient and electrical conductivity
of Bi2Te3/Al2O3 system were discussed. The experimental electrical conductivity is close to the
theoretically calculated value. Further improvement in eliminating the interface thermal resistance
would bring more reliable result in Seebeck coefficient measurement. The macro-integration
measurement is a practical method to evaluate the thermoelectric properties of thermoelectric
nanowire arrays.
Improved Line Sampling Reliability Analysis Method and its Application
Authors: Song Shu Fang , Lu Zhen Zhou
Published: March 2009

For reliability analysis of implicit limit state function, an improved line sampling method
is presented on the basis of sample simulation in failure region. In the presented method, Markov
Chain is employed to simulate the samples located at failure region, and the important direction of
line sampling is obtained from these simulated samples. Simultaneously, the simulated samples can
be used as the samples for line sampling to evaluate the failure probability. Since the Markov Chain
samples are recycled for both determination of the important direction and calculation of the failure
probability, the computational cost of the line sampling is reduced greatly. The practical application
in reliability analysis for low cycle fatigue life of an aeronautical engine turbine disc structure under
0-takeoff-0 cycle load shows that the presented method is rational and feasible.
Evaluation of Cracked Beam-to-Column Connection from Brittle Failure Using Finite Element Method
Authors: Ma Hong Wei , Cho Chong Du , Kim Chang Boo , Beom Hyeon Gyu
Published: March 2009

The bolted end-plate composite beam-CCSHRC column connection was validated to be
ductile and offered an alternative to pre-Northridge connection. This study aims at the beam lower
flange fracture in the connection test, and applies the J-integral criteria to examine the connection’s
nonlinear fracture behavior. Advanced 3-D connection models containing initial crack in the high
stress zone at lower flange are created, and the J values at the crack tip are calculated with considering
the influences of certain parameters. The results demonstrate that the J values are strongly affected by
the initial crack length and interstory drift. For 0.94, 1.35, 1.86 and 2.50 mm long crack, the J values
sharply increase during loading history. The crack with a length of 2.50 mm propagates at a 66 mm
drift, while the 1.35 mm long crack grows at a 120 mm drift. For 0.94 or 0.61 mm long crack, it keeps
stable without growing upon loading. Besides, the J values exhibit a weak sensitivity to the beam
concrete strength and tensile reinforcement ratio for beam. Under the same drift, the J-integral
increases by about 3.5% when concrete strength changes from 15 to 24 MPa, and the J values at 0.6%
tensile reinforcement ratio for beam are 1.5% larger than those at 0.3% or 1% reinforcement ratio.
Discrete Dislocation Dynamics Simulation on Strengths of Dislocation Network Stacks in Multilayered Structures
Authors: Kaneko Yoshihisa , Hirota S. , Hashimoto Satoshi
Published: March 2009

Strengths of multilayered structures have been investigated using three-dimensional
discrete dislocation dynamics (DDD) simulation. The multilayered structure was modeled as a stack
of misfit dislocation networks which must exist at an interface between adjoining crystals having
different lattice constants. Passages of a single mobile dislocation through several kinds of network
stacks were simulated. The critical stress required for the dislocation passage depended on the
dislocation spacing of the network, the number of network sheet and the spacing between network
sheets.
Numerical Investigation on the Fracture Behaviors of Three-Dimensional Functionally Graded Materials
Authors: Yu Hong Jun , Guo Li Cheng , Wu Lin Zhi
Published: March 2009

Functionally graded materials (FGMs) with continuous varying properties have absorbed
great attention for the purpose of eliminating the mismatch of material properties which may result in
cracking. In this paper, three-dimensional finite element method (3D FEM) based on
nonhomogeneous elements is used to study the fracture behaviors of a 3D FGM plate. Since real
material properties at Gaussian integration points are adopted during forming the element stiffness
matrix, the nonhomogeneous material properties can be applied in each element. Moreover, 20-node
singular elements are used around the crack front to deal with the singularity of stress fields at the
crack front. By this way, the stress intensity factors (SIFs) can be calculated with high efficiency and
accuracy. Therefore, compared with the general FEM using homogeneouos elements, the calculating
efficiency and accuracy can be increased. Finally, parameter analysis is conducted. It is found that the
material nonhomogeneity constant and the crack parameter have significant influences on the SIFs.
Analysis of Slant Surface Cracks with Step Notches Subject to Contact Loadings by a Variational Boundary Integral Method
Authors: Wang He Hui , Hu Meng Xi , Chen Yi Fan , Wang Dong Liang , Xie Ke Di
Published: March 2009

Modes I and II stress intensity factors are analyzed by means of a variational boundary
integral method (VBIM) for slant surface-breaking cracks in a half-plane with surface steps subject
to contact loadings. This method represents the crack as a continuous distribution of dislocation
loops. The crack opening displacements, which are related to the geometry of loops and their
Burgers vectors, can be determined by minimizing the elastic potential energy, obtained from the
known expressions of the interaction energy of a pair of dislocation loops, of the solid. In contrast
to other methods, this approach finally reduces to a symmetric system of equations with milder
singularities of the type 1/R, which facilitate the numerical treatments. By modeling the surface
boundary of the half-plane as half part of an infinite crack breaking through an infinite solid, this
paper demonstrates that the VBIM can be well extended to solve the fracture problems of inclined
surface-breaking cracks in a half-plane with curve or step notches subject to combined contact
loadings, and presents results of stress intensity factors for a variety of loadings, cracks and step
surface configurations. Numerical results of test examples are in good agreement with the existing
results in the literature.
A Statistical Analysis on the Fatigue Life Characteristics of Structural Materials
Authors: Kim Sang Tae , Jang Seong Soo
Published: March 2009

A new method of parameter determination in the fatigue residual strength degradation
model is proposed. The new method and minimization technique are compared experimentally to
account for the effect of tension-compression fatigue loading on structural materials. It is shown that
the correlation between experimental results and the theoretical prediction of the fatigue life, fatigue
life distribution obtained by the proposed method is very reasonable.
Study of Damage Mechanism on Aluminum Alloy under Two Kinds of Stress States and FEM Simulation
Authors: Zhu Hao , Zhu Liang , Chen Jian Hong
Published: March 2009

In order to study the damage mechanism under different stress states of aluminum alloy
components, two kinds of representative triaxial stress states were adopted, namely notch tensile
and pure shear. The results of study showed: During the notch tensile test, stress triaxiality in the
least transverse-section was relatively higher. With increasing applied stress, the volume fraction of
the microvoid in notch root was increasing constantly. When microvoid volume fraction reached the
critical value, the specimen fractured. During the pure shear test, stress triaxiality almost came up to
zero, and there was almost no micro-void but localized shear bands within the specimen. The shear
bands resulted from non-uniform deformation constantly under the shear stress. With stress
concentrating, the cracks were produced in the shear bands and later coalesced. When the
equivalent plastic strain reached the critical value, the specimen fractured. The modified Gurson
damage model and the Johnson-Cook model were used to simulate the notch tensile and shear test
respectively. Simulated engineering stress-strain curves fit the measured engineering stress-strain
curves very well. In addition, the empirical damage evolution equation for the notch specimen was
obtained from the experiment data and FEM simulations.
Fatigue Properties of Nanometer-Scale Copper Films
Authors: Zhang Bin , Sun K.H. , Gong Jun , Sun C. , Wang Zhong Guang , Zhang G.P.
Published: March 2009

Fatigue tests of nanometer-thick Cu films as deposited and annealed in vacuum were
conducted under constant load ranges at room temperature. Fatigue strengths of the Cu films, which is
defined as the critical load range being able to cause crack initiation within 106 cycles, are determined.
The experimental results show that fatigue strength increases with decreasing film thickness. Fatigue
cracking behaviors were characterized by electron microscope. It is also found that fatigue cracking
resistance is dependent on film thickness and increases with decreasing film thickness. Size effects on
fatigue properties of the nanometer-thick Cu films are discussed.
Investigation to the Effects of Grain Misorientation on the Performance of Short Cracks
Authors: Xu Yan Hai , Li Hao , Guo Li
Published: March 2009

The influences of crystallographic and geometric parameters such as grain misorientation
on the performance of short cracks are illustrated based on FEM in this paper. Firstly, the
microstructure is simulated to account for the effects of grain misorientation on the performance of
short cracks and the short cracks are initiated within the microstructure for the further investigation.
The influence of grain misorientation is demonstrated by the change of neighboring grain
orientations with an initiated short crack from 0° to 180°. The effects of the grain boundary on the
short crack with the crack arrested or retarded are described by the crack propagation until it
approached the grain boundary. The results will give more useful information such as crack arrested
and retardation to the further research on the characteristics and evolution of short cracks.
Study on Reliability Design of Fiber Wound Reinforced Plastics Pressure Vessel
Authors: Shen Jun , Xie Huai Qin
Published: March 2009

To meet the high reliability of structural design and safety evaluation on carbon fiber
wound reinforced polymeric (CFWRP) pressure vessel, the traditional safety factor design was
substituted by reliability design based on the reliability theory and statistical principle. Eight
CFWRP pressure vessels were manufactured with the same material system by the same winding
technique. And experiments were conducted to obtain the probabilistic distributions of design
variables. Results derived from reliability design (fiber thickness) agreed well with experimental
results and were much lower than that from conventional design. Through comparison among
reliability design results with different statistics of fiber strength, significant effect of the variation
of fiber strength on structural reliability of composite pressure vessel was demonstrated. The
conventional design was verified to be not reasonable since it considers only the mean value of fiber
strength without the effect of fiber strength distribution on structural resistance of pressure vessel.
Uniaxial and Multiaxial Cyclic Deformation Behaviors of SiCp/6061Al Alloy Composites
Authors: Kang Guo Zheng , Liu Yu Jie
Published: March 2009

The uniaxial/multiaxial cyclic deformation behaviors of SiCp/6061Al alloy composites
with various particulate volume fractions were studied by uniaxial and multiaxial cyclic straining or
stressing tests at room temperature. The cyclic softening/hardening features and ratcheting
behaviors of T6-treated composites and un-reinforced matrix were discussed in different loading
conditions. It is shown that the ratcheting also occurs in the composites under uniaxial and
multiaxial asymmetrical cyclic stressing, and the ratcheting strain increases with stress amplitude
and mean stress; however, the addition of SiC particulates into the matrix increases the resistance of
the composite to ratcheting. The ratcheting depends greatly on the shapes of loading paths and
mainly occurs in the direction of non-zero mean stress.
Finite Element Analysis about Effects of Particle Size on Deformation Behavior of Particle Reinforced Metal Matrix Composites
Authors: Yan Yi Wu , Geng Lin , Li Ai Bin , Fan Guo Hua
Published: March 2009

By incorporating the Taylor-based nonlocal theory of plasticity, the finite element
method (FEM) is applied to investigate the effect of particle size on the deformation behavior of the
metal matrix composites. In the simulation, the two-dimensional plane strain and random
distribution multi-particles model are used. It is shown that, at a fixed particle volume fraction,
there is a close relationship between the particle size and the deformation behavior of the
composites. The yield strength and plastic work hardening rate of the composites increase with
decreasing particle size. The predicted stress-strain behaviors of the composites are qualitative
agreement with the experimental results.
Influence of Extrusion Temperature on Microstructures and Mechanical Properties of Bi2O3-Coated Al18B4O33 Whisker Reinforced Al Composites
Authors: Fei Wei Dong , Li Zhi Jun , Yue Hong Yan , Wang Li Dong
Published: March 2009

Extrusion experiments have been carried out on Bi2O3-coated Al18B4O33 whisker
reinforced aluminum matrix composite. The effects of the extrusion temperature on the
microstructures, the formability and the mechanical properties of ABOw reinforced aluminum
(ABOw/Al) composites with and without Bi2O3 coating were investigated. The results show that the
steady-state extrusion load and the probability of whisker fracture of the extruded two composites
decrease with the extrusion temperature increasing. The mechanical properties of the composites
attain highest values at extrusion temperature of 673K.
Effects of Polarization Treatment on Mechanical Properties of Al2O3/LiTaO3 Composite Ceramics
Authors: Zhang You Feng , Meng Qing Chang , Jia De Chang , Zhou Yu
Published: March 2009

The Al2O3/LiTaO3 (ALT) composite ceramics were fabricated by hot pressing method
and polarization treated at different temperatures along height and width directions. Effects of
polarization treatment on mechanical properties of the ALT composite ceramic were investigated.
Flexural strength decreased with the increase of polarization temperature. Meanwhile, the flexural
strength of samples polarized in height direction is higher than that polarized in width direction. The
composite ceramic fractures intragranularly, and many rupture steps in polarization direction were
observed on fractographs of the composite ceramics. Domain switching in LiTaO3 particles
increased the resistance of crack propagation and improved the mechanical properties of the
polarized ALT composite ceramics.
The Action Mechanism of Preparation of Calcium Carbonate/Titanate Composite Material by Mechano-Activated Method
Authors: Ding Hao , Liu Yan Gai , Deng Yan Xi , Du Ya Li
Published: March 2009

The action mechanism between titanate and calcium carbonate in preparation of calcium
carbonate/titanate composite material was studied by infrared spectrometry(IR) and X-ray
photoelectron energy spectroscopy(XPS) analysis. The results show that adsorption of titanate could
occur through chemical reaction with calcium carbonate surface. The chemical adsorption model of
titanate on calcium carbonate surface was thus established on the basis of these analysis results.
Fracture Characteristic of Mg-Al-Zn-Al2O3 Composites
Authors: Geng Hao Ran , Wang Shou Ren , Teng Xin Ying , Hui Lin Hai , Xu Fu Song
Published: March 2009

One kind of 3DNMMC with different volume fraction reinforcement phase was
fabricated by pressureless technique. The bending strength and fracture toughness were tested by
3-P bending strength experiments. When the volume fraction of reinforcement phase phase was not
in excess of 10%, composites had an improvement of bending strength and fracture toughness
owing to relatively homogeneous Al2O3 particle distribution encircled by metal matrix and the
occurrence of interface reaction product as MgAlO2 spinel phase. Much and smaller craters and
dimples are observed in metal matrix alloy and limited ductility of composites causes the early
failure of composites. With the increases of volume fraction of reinforcement phase phase, crack
characteristic consist of crack nucleation, growth, coalescence and crack propagation became the
main fracture failure mechanisms.
Room Temperature Creep and its Effect on Fatigue Crack Growth in a X70 Steel with Various Microstructures
Authors: Nie De Fu , Zhao Jie
Published: March 2009

Fatigue crack growth (FCG) tests have been performed in an X70 steel with various
microstructures (respectively in the as-received and the normalized condition). The effect of room
temperature creep (RTC) on FCG behavior has been investigated by comparing with single wave
overloads (SWOL). The as-received X70 pipeline steel has high FCG rate at the near-threshold
region. While at the Paris region, FCG rate seems insensitive to the microstructure. In both
conditions, time-dependent deformation is observed at crack tips (i.e., RTC), which increases with
increasing stress-intensity-factor. And this deformation has a high value in the normalized state,
under identical testing conditions. Both RTC and SWOL can bring subsequent fatigue crack growth
a very short initial acceleration before deceleration, whereas the former induces more serious
deceleration and retardation, which attributes to more significant crack closures.
FRP Fracture Simulation Using Parallel Processing on a PC Cluster
Authors: Shimamura Yoshinobu , Yamamura Yosuke , Todoroki Akira
Published: March 2009

Recently, applications of integrated large composite structures have been attempted to
many structures of vehicles. In order to improve the cost performance and reliability, it is necessary to
judge the structural integrity of composite structures. Fracture simulation techniques using FEM have
been developed for the purpose. Since a number of iterations of finite element analysis are required in
the fracture simulation, the simulation techniques consume many memory resources and much
calculation time. In this study, a personal computer cluster (PC cluster) and the domain
decomposition method were incorporated into a fracture simulation system. Calculations using a
Windows PC cluster were carried out to confirm the efficiency of the proposed simulation system. As
a result, it is concluded that adopting the domain decomposition method and the computer cluster is
remarkably efficient to reduce calculation time.
Mechanical Properties of SiCp/Cu Composites Prepared by Electric Conduction Sintering
Authors: Wang Chun Hua , Guan Shaokang , Li Shou Shan , Zhang Rui
Published: March 2009

SiCp/Cu composites were fabricated at 700 oC and under 40MPa for 10min in vacuum by
electric conduction sintering. The mechanical properties and microstructure of the composites were
studied. The porosity of the composites increases when the volume fraction of SiCp exceeds 35%.
The flexural strength of the composites decreases with increasing fraction of SiCp. The composites
with 10 vol.% SiCp exhibited ductile fracture behavior, while composites with the volume fraction
of SiCp in the range of 20–65% exhibited brittle fracture behavior. The composites with 35 vol.%
SiCp showed the highest hardness.
Preparation of Novel Aluminum Hybrid Composite Containing Aluminum Borate Whiskers and Carbon Nanotubes
Authors: Zhang Xue Xi , Shen Yong Bing , Deng Chun Feng , Wang De Zun , Geng Lin
Published: March 2009

It is attractive to use multi-wall carbon nanotubes (MWNTs), which has a high modulus
and strength, to enhance the properties of metal matrix composites by hybrid strategy. In this paper,
novel aluminum borate whisker (ABOw) and MWNTs hybrid composites were prepared by squeeze
cast technique and the properties were investigated. The results show that hybrid preforms may be
made by co-deposition of ABOw and MWNTs in a solution by wet method. MWNTs separate the
ABOw from whisker-to-whisker contact and decrease the compressive deformation of the hybrid
preforms during squeeze cast processing. MWNTs distribute along mainly in the grains of
aluminum matrix, making the mechanical properties of the hybrid composites higher than singularly
reinforced composite.
Monitoring of Delamination of the CFRP Beam by the Smart Structure System Using the SI-F Method
Authors: Yuguchi K. , Iwasaki Atsushi , Shimamura Yoshinobu , Todoroki Akira
Published: March 2009

The structure with the sensor and the actuator is called Smart Structure. Installation of
the sensor and the actuator to the structure enables the automatic damage detection. In this paper, a
novel damage detection method called “SI-F method” is applied to the Smart Structure to detect the
delamination in the CFRP beam. The artificial delamination in the CFRP is introduced by the
out-of-plane bending. CFRP beam will be exited by the PZT actuator, and the strain of the surface
will be measured by the strain gauge. As the result, the delamination is successfully detected by
varying the condition of the excitation.
Microstructure and Mechanical Properties of 2D Tyranno SA/SiC Composites by Hot Pressing
Authors: Dong Shao Ming , Ding Yu Sheng , Zhou Qing , Kohyama Akira
Published: March 2009

SiC/SiC composites were fabricated by hot pressing (HP) via liquid phase sintering (LPS)
using carbon coated 2D woven Tyranno SA fabrics as reinforcement. Both nano-SiC and micro-SiC
powders with sintering additives were used for matrix. The effects of preparation conditions on the
microstructure and mechanical properties of the composites were characterized. Highly densified
composite was obtained at 1780°C under 20MPa with nano-SiC particles. The strength and elastic
modulus of the composite were enhanced. When micro-SiC powder was used, higher strength
revealed for the composite sintered at 1780°C under 15MPa, although it was not densified enough.
Higher sintering temperature (1800°C) is beneficial for the densification of the composite, but is not
obvious for the improvement of mechanical properties.
The Micromechanical Stress Field of Cermets Composite Containing Interfacial Arc-Microcracks
Authors: Ni Xin Hua , Yao Zhan Jun , Zheng Jian , Kang Jing Xin
Published: March 2009

The emerging cause of arc-microcracks is interpreted and the interaction between
ceramic particles and arc-microcracks is accounted for determining the average disturbance strain
and equivalent eigen strains by using Mori-Tanaka method. Then the micromechanical stress field
of the cermets is estimated. Results show that the micromechanical stress field is not associated
with the distribution of arc-microcracks. The stress in matrix and ceramic particles will increase
when the volume fractions of arc-microcracks increases.
Electrically Nonlinear Fracture Analysis of Piezoelectric Materials Based on CED (Crack Energy Density)
Authors: Liu Rong Feng , Nam Byeung Gun , Watanabe Katsuhiko
Published: March 2009

An electrical nonlinear constitutive model for piezoelectric material is studied in this
paper. Electric yielding criterion and yielding effect on CED are investigated. Using the mechanical
part of CED as a fracture parameter, it is shown that the predicted fracture loads through FEA for
compact tension specimen is in accordance with corresponding experimental results.
Investigation on Large-Sized Sapphire Crystalline Perfection by X-Ray Double-Crystal Diffraction Method
Authors: Wang Gui Gen , Zhang Ming Fu , Zuo Hong Bo , He Xiao Dong , Han Jie Cai , Benik Grigoryan , Xu Cheng Hai , Yao Tai
Published: March 2009

The large-sized sapphire (Ø225×205 mm, 27.5 kg) was grown successfully by SAPMAC
method (sapphire growth technique with micro-pulling and shoulder-expanding at cooled center).
The surface quality of the specimens was characterized by micro-Raman spectroscopy, and double
crystal X-ray diffractometry (DCD) was utilized to investigate its crystalline perfection. The
measurement of rocking curves was performed on various specimens from different region of large
sapphire boule. The experimental results showed that CMP (chemo-mechanical polishing) with
subsequent suitable chemically etching can develop the best-quality sapphire crystal surface and the
values of FWHM obtained by conventional DCD were in the range from 27” to 58”. The infrared
spectral transmission (2.0-4.5 5m) of sapphire crystal exceeded 82%. It is confirmed of SAPMAC
growth method characteristics with in-situ annealing, small temperature gradient and low residual
stress level by numerical simulation analysis.
In Situ Toughened α-Sialon Ceramics Doped with Lutecia and Ytterbia
Authors: Liu Chun Feng , Ye Feng , Zhou Yu
Published: March 2009

Ytterbia and Lutecia were adopted to stabilize α-sialon ceramics during a two-step hot
press sintering, respectively. Although Yb3+ and Lu3+ possess the similar small ion size (0.86 Å and
0.85 Å) as two adjacent rare-earth elements, Yb- and Lu-α-sialon ceramics present very different
microstructure and properties. Yb-α-sialon ceramic is fully composed of α-sialon phase without any
secondary phase. The ceramic incorporated with Lu2O3 also consists of α-sialon phase, but a trace
amount of intergranular phase J′ (Lu4Si2-xAlxO7+xN2-x) still remains at the boundary. Microstructure
observation indicates the fully equiaxial grain morphology of Yb-α-sialon ceramic. However,
elongated grains appear in the Lu-α-sialon ceramic, coexisting with small equiaxed grains. Owing
to the almost full α-sialon phase assemblage, both ceramics present high hardness with the value of
over 21 GPa. Lu-α-sialon ceramic possesses good toughness, which is attributed to the elongated
grains assisting the facilitation of toughening mechanism. The equiaxied grain morphology results
in a comparatively lower toughness for Yb-α-sialon ceramic.
Analysis of a Thin Electrode Layer between Two Dissimilar Piezoelectric Solids
Authors: Beom Hyeon Gyu , Kim Y.H. , Cho C. , Kim Chang Boo
Published: March 2009

A thin electrode layer at the interface between two dissimilar linear piezoelectric materials
under electromechanical loading is investigated. The complex function theory is employed to obtain
the exact solution to a finite thin conductive layer. Special consideration is devoted to the structure of
singular stress and electric fields near the tip of the thin electrode between two dissimilar piezoelectric
materials. The stress and electric field are found to have an inverse square root singularity. The
electric field intensity factor characterizes uniquely the singular fields close to the edge of the
conductive line sheet.
Tribology of Titanium Boride Sliding against Silicon Carbide at Elevated Temperatures
Authors: Xiao Han Ning , Yin Ji Xiang , Senda Tetsuya
Published: March 2009

Friction and wear tests of TiB2 sliding against SiC were conducted without lubricant from
room temperature to 1200°C in air and in vacuum. The friction coefficient of the couple of
TiB2/SiC is affected obviously by the oxidation of TiB2. It increases with the increase of
temperature and reaches a maximum at some temperature in air, then decreases remarkably. The
friction coefficient of TiB2/SiC in vacuum exhibites almost a constant and keeps smaller value than
that in air. Transition of TiB2 onto the sliding surface of SiC was observed, which improved the
wear resistance of SiC at high temperatures.
Effects of Preparation Processing on Mechanical Properties of TiAl Intermetallic
Authors: Chen Wen Zhe , Peng Kai Ping , Qian Kuang Wu
Published: March 2009

Mechanical properties of the TiAl alloy produced by centrifugal spray deposition (CSD),
compared to that produced by ingot metallurgy (IM), were investigated at different temperatures
from 293 to 973K. The result shows that the ultimate strength, yield strength and plasticity of the
CSD TiAl alloys, with excellent compression properties and plasticity, are higher than those of
as-cast TiAl alloys at room temperature as well as at high temperature. There exists a critical
temperature of 873K in the relationship between strength and temperature, in which strength
increases with increasing temperature above 873K. The effects of CSD on mechanical properties of
the TiAl alloy are discussed, and the higher strength with moderate ductility achieved is because of
the finer lamellar structure got in the CSD processing, and this structure is also believed to be
beneficial to ductility.
Microstructural Evolution of Inconel 690 Alloy for Steam Generator Tubes
Authors: Park N.K. , Kim Jeong Joo , Chai Young Suck , Lee H.S.
Published: March 2009

Inconel 690 alloy is a Ni-Cr-Fe austenite solid solution alloy with a wide range of
applications such as steam generator tubes in nuclear power plant due to its good mechanical
properties and corrosion resistance. In this study, the effects of heat treatment on the microstructural
properties of Inconel 690 alloy were investigated. Inconel 690 alloy was annealed at solid solution
temperature of 1150°C for 20 min, and cooled down to 800°C with different cooling rates, and then
aged at 800°C for 100 min in vacuum, and then cooled down to room temperature by water
quenching. The optical microscopy, scanning electron microscopy, and transmission electron
microscopy results indicated that in case of the cooling rate of 0.5°C/min, discontinuous carbides
along the grain boundaries were formed and when the cooling rate was 10°C/min, continuous
carbides were formed. In both cases, many annealing twins were also formed. These results can
help to improve the understanding of microstructural properties of Inconel 690 alloy.
Investigation on Residual Stress and Crystallographic Texture of YSZ Films Prepared by EB-PVD
Authors: Meng Bin , He Xiao Dong , Sun Yue , Li Ming Wei
Published: March 2009

Yttria Stabilized Zirconia (YSZ) films were prepared by electron beam physical vapor
deposition (EB-PVD) technique with a high deposition rate up to 1μm/min. An improved sin2ψ
method was employed to analyze the residual stress of films by means of grazing incidence X-ray
diffraction (GIXRD). The result of residual stress measurement reveals that residual stress of YSZ
film is compressive stress and keeps a linear relationship with the deposition temperature, which is
induced mainly by the thermal expansion mismatch between the film and substrate. The XRD result
of films, prepared with different incident angles, demonstrates that the films show preferred
orientation evidently. Furthermore, a parameter ωhkl was introduced from the inverse polar figure
measurement theory to reveal the degree of preferred orientation clearly. The calculating result of ωhkl
value indicates that the preferred orientation of different specimens changes with the incident angles,
which is due to columnar growth pattern of films prepared by EB-PVD. In order to characterize the
crystallographic texture visually, XRD with 2D detector system was used to analyze the texture of
films. The result shows that Debye rings appear asymmetric intensively, which denotes the existence
of preferred orientation directly and agrees with the calculating result of ωhkl value.
Simulation on Temperature Distribution in Chemical Mechanical Polishing
Authors: Liu Jin Quan , Zhang Chao Hui , Ye Wei
Published: March 2009

Temperature rise has two-edged influences on chemical mechanical polishing (CMP)
process: temperature-rise facilitates the chemical activity and the motion of the nano particles
contained in the slurry through which material removal ratio (MRR) is enhanced; to the other side of
the same coin, however, it will soften the pad surface and subsequently reduce the MRR. Thus the
research on temperature distribution of CMP process will be conducive to discovering the mechanism
of polishing, and acquiring stable MRR and improving surface quality. With the help of the
knowledge of tribology, hydrodynamics, and thermodynamics, flow equation considering the
temperature variation in the fine step of CMP process, wherein high surface quality is the main
concern and usually operates in contact free state, is set up, based on which the temperature field in
contact is investigated in detail by taking advantage of the simulation technique, and the heat energy
production and transition relations are obtained. Due to the slurry used, a small viscous heating effect
is acknowledged by simulated results, and the temperature rise is negligible in contact-free flows,
which is very conducive to the promotion of the final polished wafer/disk surfaces. The research will
surely shed some lights in the mechanism of CMP and lay a feasible foundation for possible future
utilization.
The Improvement of Corrosion Resistant for the Cf/Al Composites by Ni-P Coatings
Authors: Wang Chun Yu , Wu Gaohui , Kang Peng Chao , Zhang Yun He , Xiu Zi Yang , Chen Guo Qin
Published: March 2009

Improved corrosion resistance of carbon fiber reinforced aluminum (Cf/Al) matrix
composites can be achieved by applying appropriate coatings, and the electroless plating
nickel-phosphor (Ni-P) coatings on the Cf/Al composites was provided in this paper. It has been
founded that the pretreatment with zinc dipping solution for the electroless plating Ni-P can be
approved perfect coatings on the Cf/Al composites. The EDS lines scanning results that the length
of Ni-P coating is about 12 +m. In zinc dipping bath, matrix Al alloy surface could catch hold of
action points for depositing Ni-P with substitution reaction, however, carbon fibers surface only
have adsorption action points from zinc dipping bath, then, Ni-P alloys could deposit on the Al
surface or carbon fibers. The uncoated and coated composites samples immersed in 3.5 wt % NaCl
solution to contrast. The pitting corrosion behavior of the uncoated composites destroyed materials,
therefore, the coated sample appeared pitting only on the surface. The corrosion resistance
mechanisms of Ni-P coatings came from inhabiting the formation of the classical galvanic corrosion,
additionally, the Ni-P coating was amorphous structure, there was not grains boundary which is
sensitive for the corrosion reaction, so the corrosion resistant of Cf/Al composites were improved.
A Theoretical Model for Squeeze Film Dampers Operating with Air Entrainment
Authors: Zhao Chun Yu , Yao Hong Liang , Lin Feng , Wen Bang Chun
Published: March 2009

A continuum model of the evolution of air ingestion and entrainment for open-ended
squeeze film dampers is proposed in this paper. Hydrodynamic lubrication theory is extended to
lubrication with mixture of a Newtonian liquid and an ideal gas. The solution to the universal
Reynolds equation is determined numerically using a control volume method (Elrod algorithm) and
the forth-order Range-Kutta method. This method conserves mass throughout the computational
domain including air ingestion and entrainment. Excellent agreement is found with the experimental
works of Diaz and San Andrès for the squeeze film damper [1, 2].
Microstructure and Properties of Ni3 (Si, Ti) Intermetallic Cladding with Nb Addition
Authors: Sun Yao Ning , Fan Ding , Sun Ming , Zheng Yu Feng , Zhang Jian Bin
Published: March 2009

Laser cladding technique was used to form Ni3(Si,Ti) intermetallic coating by Nb addition
on Ni-based superalloy substrate. The coating was investigated by optical microscopy and X-ray
diffraction (XRD). The clad coating was dense, compact and smooth. An excellent bonding between
the coating and the substrate was ensured by a strong metallurgical interface. Ni3(Si,Ti) phase was
detected in all of the claddings, and NbNi3, Nb3Ni2Si were detected in Nb additional experiments. The
peaks intensity of Nb3Ni2Si and NbNi3 increased with the increasing of Nb content. The Ni3Nb and
Nb3Ni2Si were formed when Nb was beyond its solubility in the L12 Ni3(Si,Ti). The average
microhardness of the coating was improved with the increasing of the Nb content. The microhardness
was up to 530Hv when the atom percentage of Nb addition reached 5%, and it was much greater than
that of Ni-based superalloy substrate.
Influence of Testing Frequency on Fatigue Crack Growth of 6061-T6 Aluminum Alloy in Hydrogen Gas Environment
Authors: Hagihara Akiyoshi , Oda Yasuji , Noguchi Hiroshi
Published: March 2009

In order to investigate the effects of testing frequency on the fatigue crack growth rate of
6061-T6 aluminum alloy in hydrogen gas environment, fatigue crack growth tests were carried out on
specimens with small artificial holes in 0.18 MPa hydrogen gas or in 0.18 MPa nitrogen gas. It takes
long time to test at low testing frequency, so in this study an accelerated test method was proposed and
fatigue tests were carried out using this method. The fatigue crack growth rate in hydrogen gas
environment accelerates compared with in nitrogen gas environment. The crack growth rate at lower
testing frequency tends to higher.
Plasma Surface Alloying Process of a Fe-W-Mo-Co Surface Age Hardening High Speed Steel
Authors: Li Zhong Hou , Ren Nai Juan , Zhang Yan Mei
Published: March 2009

The surface age alloy of Fe-Co-W-Mo was formed on 25Cr2Mo2V steel by double glow
plasma surface alloying technique. The effects of processing parameters on the depth, composition
and constituent phases of surface alloying layer were investigated. Results indicate that the plasma
processing parameters influenced significantly the surface alloying process. The composition of the
surface layer nears W11Mo7Co23Fe59wt%, the depth of the surface alloying layer is 150μm after
processing at 1100°C for 6hr. The microstructure of the cross section was composed of three
sub-layers, that is, the deposition layer, the diffusion layer and the matrix. The constituent phases of
the deposition layer were Fe7W6 type μ phase Fe2W type laves phase, Fe3Mo and a little amount of
M2C type carbide, that of the diffusion layer were α-Fe and some intermetallics.
Tribological Behavior of DLC Films by RF-PECVD at the Elevated Temperature
Authors: Cho Yong Kyung , Shin Yun Ha , Jeong Sung Hoon , Lee Young Ze
Published: March 2009

The tribological behaviors of Diamond-like carbon (DLC) films, prepared by the radio
frequency plasma enhanced chemical vapor deposition (RF-PECVD) method, were studied in the
room temperature and the elevated temperature. The ball-on-disk tests with DLC films on steel
specimens were conducted at a sliding speed of 60 rpm, a load of 10 N, and surrounding temperatures
of 25°C and 75°C. The results show that the coefficients of friction and the amounts of wear of DLC
films were decreased at higher temperature. After tests the wear tracks of hydrogenated DLC film
were analyzed by Raman spectroscopy.
Some Problems on Evaluating Elastic Modulus of APSed Ceramic Top Coat for TBCs by Indentation Method
Authors: Okazaki Masakazu , Ozaki T.
Published: March 2009

Elastic modulus of air plasma sprayed (APSed) YSZ (; ZrO2 stabilized by 8 wt. pct. Y2O3)
top coat specimen, which is frequently used for thermal barrier coating (TBC) system for advanced
gas turbines, was measured by employing the macro-, micro-, and nano-indentation methods. The
elastic modulus was measured, following the Oliver-Pharr method. It was shown that the elastic
modulus of the YSZ, as well as the microstructure, was significantly influenced by the spraying
conditions employed. Especially the size of ceramic powders used was found to have the most
pronounced effect. It was also shown that the elastic modulus revealed significant size effect: that is,
there were significant differences in elastic modulus measured by the instruments on the macro-,
micro-, and nano-levels. This size effect was discussed, correlating with some relating phenomena:
crackings, sink-in, pile-up and spalling; as well as with the characteristic microstructures of the
sprayed top coat.
Evaluation of Silica Content on Fracture Toughness of PI/SiO2 Hybrid Films
Authors: Wang Zheng Dao , Lu J.J.
Published: March 2009

The effect of silica content on plane-stress fracture toughness of Polyimide/silica
(PI/SiO2) composite films was studied using the specific essential work of fracture (EWF) method.
The specific essential and non-essential work of fracture for PI/SiO2 hybrid thin films with different
silica doping levels was tested by experiment. The shape factor of the plastic region and specific
non-essential work of fracture per unit volume were received by finite element (FE) calculation. It
demonstrated that the plastic zone for specimens studied here was much different from the
traditional result given through optical microscopic observation.
Colossal Magnetoresistance Effects of La1-xSrxMnO3
Authors: Jiang Shao Qun , Ma Xin Xin , Sun Ming Ren , Wang Gang , Tang Guang Ze
Published: March 2009

Polycrystal samples of La1-xSrxMnO3 (x=0.2, 0.3) have been synthesized using a sol-gel
method. The effect of sintering process on the sample microstructure and Sr doping on the
magnetoresistance for La1-xSrxMnO3 have been investigated. The results show that the increase of
sintering temperature and time can promote the crystallization of samples and reduce the content of
impurity. The additive of Sr makes Mn ion in materials relatively compact, and this causes the
distorted deformation of the materials structure. The magnetoresistance (MR) changes with the Sr
doping. When x=0.2, the maximum MR% of sample is about 43% and keep about 40% between
10~150K. At room temperature, the MR% will decrease to about 6.5%. When x=0.3, the order
magnetoresistance (OMR) effect occures above the room temperature.
Processing of Environment Protective Phosphating and its Coating Properties
Authors: Wang Xiu Chun , Li Mu Sen , Pan Xi Qing , Wang Xiu Xin , Li Xiao Jun
Published: March 2009

This paper dealt with an environment protective phosphating with hydroxylamine
sulphate as main accelerant. There were no nickel ion, nitrite, benzene and other harmful substances
in the phosphated coatings. The structure, component and properties of the coatings were analyzed.
The phosphating process and its influence on powder, electrophoresis and heavy anti-erosion
coatings were also studied. The results showed that this processing had some virtues, all of the
processing was carried out at room temperature; the phosphated coating was fine and the service
life of the phosphating solution is longer. And also the phosphated coating had good properties.
Study of Boron-Doped Diamond Films by Microwave Plasma CVD Method
Authors: Murakami Riichi , Fukui Shinichiro , Yonekura Daisuke , Yim Cheolmun
Published: March 2009

Boron-doped diamonds were deposited by microwave plasma chemical vapor deposition
(MPCVD) method in order to investigate the influence of inlet boron concentration on the film
properties. The substrate material of the specimens was pure titanium (99.9 %). Boron source was
introduced into the vacuum chamber by bubbling of B2O3, acetone and methanol mixture. Samples
were produced with different B2O3 concentrations in mixture (1000 ppm, 5000 ppm, and 10000 ppm).
The surface morphology of the samples was observed by scanning electron microscope (SEM). X-ray
diffraction was used to identify crystal structures of the films. Secondary ion mass spectroscopy was
used to examine the qualitative boron contents in the films. For low B2O3 concentrations in liquid
mixture (1000 ppm), the surface morphology of the film showed both micro crystalline diamond and
nano crystalline diamond. For medium B2O3 concentrations in liquid mixture (5000 ppm), the surface
morphology of the film was also consisted of micro crystalline diamond and nano crystalline
diamond. However, the content of micro crystalline diamond decreased in comparison with low B2O3
concentration. For high B2O3 concentration in liquid mixture (10000 ppm), the surface morphology of
the film was almost dominated by nano crystalline diamond. Therefore, the crystal size of boron
doped diamond decreased with increasing boron concentration. From these results, it appears that
boron will restrain the growth of diamond crystal during deposition.