bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Infiltration Additives on the Phase, Microstructure and Oxidation Resistance of SiC Coating for Graphite Materials
Authors: Huang Jian Feng , Deng Fei , Cao Li Yun , Wu Jian Peng , Luo Hong Jie
Published: March 2009

Oxidation resistant SiC coating for graphites was prepared by a pack cementation process with
mixture powders of Si, C, SiC and some infiltration additives containing MgO, Al2O3 and Cr2O3. The
influence of different infiltration additives on the phase, microstructure and oxidation resistance of SiC
coating was primarily investigated. The results showed that adding infiltration additive in the pack
powders is helpful for depositing denser SiC coating on graphite substrate; and the coating prepared by
using MgO as infiltration additive exhibited better oxidation resistance at high temperature. XRD
analyses revealed that SiC coating prepared by adding of MgO as infiltration additive possessed more free
silicon; and the SEM analyses displayed that the free silicon could effectively fill the small holes of the
SiC coating, which resulted in a perfect dense surface structure of SiC coating. Oxidation test showed that
the as-prepared SiC coating could effectively protect graphite materials at 1500oC for 200 hours and the
corresponding weight loss of the coated graphite was only 0.13%.
A Comparison of the Surface Properties of DLC and Nanocrystalline Diamond
Authors: Lee Chong Mu , Kim Kyung Ha
Published: March 2009

Diamond-like carbon (DLC) films have been deposited by radio frequency plasma enhanced
chemical vapour deposition (rf-PECVD) with different Ar-CH4 mixtures. Nanocrystalline diamond films
have been deposited by microwave plasma-enhanced chemical vapour deposition (MPCVD), using
Ar-H2-CH4 mixtures. X-ray photoelectron spectroscopy (XPS) and nanotribological investigation (by
scanning force microscopy) have been used to compare the mechanical properties and structures of these
films. Highly orientated and non-orientated microcrystalline diamond films and MPCVD-produced
amorphous carbon have also been studied by way of comparison. The diamond films exhibit a linear
relationship between roughness and the coefficient of friction. The DLC and amorphous carbon have
higher friction coefficients than the best performing diamond film, but may more easily be deposited as
smooth coating. Possible applications for these various carbon-based films include microelectromechanical
components, for which smooth, hard coatings are required.
Analysis of Heat Transfer and Thermal Stress in Thermal and Environmental Barrier Coatings
Authors: Xiao Jin Sheng , Liu Chun Xiao , Zhao Wen Hua , Fu Wei Biao
Published: March 2009

A kind of gradient thermal and environmental barrier coating applied in internal combustion
engine is brought forward to improve its reliability, emission and efficiency. The multi-layer plate and
cylinder models are established for the simulations of heat transfer and thermal stress in the coatings.
Both the theoretical and the numerical analysis with multi-layer cylinder model with coating inside are
carried out and compared. The results show good agreement.
Composition Range of Morphotropic Phase Boundary and Electrical Properties of NBT-BT System
Authors: Dai Ye Jing , Pan Jin Song , Zhang Xiao Wen
Published: March 2009

(Na0.5Bi0.5)TiO3 (BNT) system ceramics are considered to be an excellent candidate for leadfree piezoelectric ceramics. In this paper, (1–x)Na0.5Bi0.5TiO3-xBaTiO3 (x = 0.03 ~ 0.10) was synthesized by conventional mixed-oxide technique. The powders were calcined at 950oC for 2 h and the pressed disks were sintered at 1145oC for 2 h in air atmosphere. The phase structure was investigated by X-ray diffraction technique (XRD). It is revealed that the morphotropic phase boundary (MPB) lies in a narrow composition range of x=0.05–0.08 but not a unique composition (x = 0.055 or 0.06) as shown before [1-4]. The microstructures of the ceramics were investigated by scanning electron microscopic. In addition, the piezoelectric and dielectric properties of this system were also investigated. It was indicated that both the piezoelectric and dielectric properties are better with the compositions lie near the tetragonal phase within the MPB than that whose compositions lie near the rhombohedral phase.
Preparation and Thermal Decomposition Mechanism of Zn2+-Doped Mg,Al-Hydrotalcite Nanocrystalline
Authors: Ren Qing Li , Luo Qiang
Published: March 2009

The highly pure nanocrystalline Mg,Al-hydrotalcite with Zn2+ doping was synthesized by the
one-step liquid reaction method at atmospheric pressure. And the preparation of the Zn2+-doped
Mg,Al-hydrotalcite nanocrystalline was investigated according to the results of XRD, TEM, IR and DSC.
Moreover, based on the DSC test results, the thermal mechanism functions of the Mg,Al-hydrotalcite with
Zn2+ doping are studied in detail after calculation and comparison.
Self-Assembled Monolayer of Silver Nanorods for Surface-Enhanced Raman Scattering
Authors: Yang Yong , Nogami Masayuki
Published: March 2009

Surface-enhanced Raman scattering (SERS) integrates high levels of sensitivity with spectroscopic precision and thus has tremendous potential for chemical and biomolecular sensing. The key to the wider application of Raman spectroscopy using roughened metallic surfaces is the development of highly enhancing substrates for analytical purposes, i.e., for better detection sensitivity of tracing contaminants and pollutants. Controlled methods for preparing nano-structured metals may provide more useful correlations between surface structure and signal enhancement. Here, we self-assembled silver nanorods on glass substrates for sensitive SERS substrates. The enhanced surface Raman scattering signals were observed and mainly attributed to the local field enhancement.
Preparation and Properties of (La, Sr) MnO3 Thin Films Prepared by Sol-Gel Method
Authors: Jiang Kuo , Bao X.Y. , Gong Sheng Kai
Published: March 2009

LSMO films with various thicknesses were prepared on single crystal Si (111) substrates by sol-gel process. The films were dense and had a uniform microstructure. The films showed metallic conduction characteristics at low temperature and insulator characteristics at high temperature. The metal-insulator transition temperatures (Tmi) of the films were remarkably lower than that of the bulk ceramics. The effect is related to the distortion of crystal lattice resulted from the residual stress in the films.
Anticorrosion Behaviours of the TiO2 / WO3 Composite Photoelectrodes for 304 Stainless Steel
Authors: Li Hong Yi , Ling Yun Han , Jiang Bo , Jiang Wu Feng , Guo Zhi Hong , Bai Xin De
Published: March 2009

TiO2 is one kind of semiconductor-based photocatalyst. TiO2 shows relatively high reactivity
and chemical stability under ultraviolet (UV) light. However TiO2 is a poor absorber of photons in visible
light. In order to improve the absorption efficiency, the coatings of TiO2/WO3, WO3 and TiO2 on ITO
were prepared by liquid phase deposition (LPD) and dip coating method, their microstructure, surface
properties, photoelectrochemical properties are investigated in this paper. XRD results showed that the
phases on the composite coatings are mainly anatase, rutile and WO3 respectively, the SEM results
showed that the coatings of TiO2 and TiO2/WO3 are distributed evenly on the materials surface. The
electrochemical experiment results showed that open circuit potential of TiO2 and TiO2/WO3 with
presence of the UV light illumination were about -343 mV and –650 mV respectively, comparatively the
rest potential of 304 stainless steel is about 48 mV, which means that the TiO2 or TiO2/WO3 coatings can
protect 304 stainless steel from corrosion, and TiO2/WO3 coatings retained for a while anticorrosion even
absence of UV light.
Reaction Process of Al-TiO2-C-Ti-Fe Multiphase System during Combustion Synthesis
Authors: Meng Song He , Zhang Xing Hong , Zhang Wei Feng
Published: March 2009

The reaction process and kinetics of Al-TiO2-C-Ti-Fe system were investigated by differential
scanning calorimetry (DSC) analysis, X-ray diffraction (XRD) analysis and scanning electron microscope
(SEM). In order to obtain the information of reaction process for complicated system, the reaction
characteristics of Al-TiO2, Al-TiO2-C and Al-TiO2-C-Ti systems are explored firstly. The results show
that the reaction process varies with temperature in Al-TiO2-C-Ti-Fe system. At the lower temperature,
the dominating reaction in Al-TiO2-C-Ti-Fe system is that between Al and Ti, Al and Fe, and so TiAlx,
FeAlx, and Ti2Fe intermetallic compounds form. With the temperature increasing, the intermetallic
compounds are decomposed. Then the decomposed Ti and Al react with C and TiO2 respectively and the
stable TiC, Al2O3 and Fe three phases form in the final product.
Sintering Behavior of Fe-Si Composite Powder by DPR Technique
Authors: Shen Qiang , Zhou Y. , Li Jun Guo , Yuan W.J. , Zhang Lian Meng
Published: March 2009

The reaction mechanism of silicon and iron composite powders was clarified during the fabrication of high silicon iron sheet with the Si-content of 6.5wt% by Direct Powder Rolling (DPR) technique. The changes of phase composition and structure evolvement were mainly studied. It is found that a local graded structure, Fe-Fe(Si)-Fe3Si(Si)-Si, forms when sintering at 950-1000oC, which plays an important role in the DPR process. Fe3Si(Si) phase keeps higher content of Si, and Fe(Si) phase remains the state with much lower Si-content, thus provides good mechanical proprieties of rolling and cutting. Then, the subsequent sintering at about 1200oC improves the density and makes the distribution of Si homogeneous in the final high silicon iron sheets.
The Stability of TZP-YSZ Binary Suspensions
Authors: Li Ping Yun , Li Guo Jun , Ren Rui Ming
Published: March 2009

The binary micrometer YSZ-TZP suspensions were prepared for the gel-casting molding of YSZ electrolyte in order to improve the mechanical properties of YSZ. The potential, sedimentation and viscosity of YSZ, TZP and TZP-YSZ suspensions were investigated. The results indicated that the dispersant (PAA NH4) can greatly affect the surface chemical properties of both YSZ and TZP, and it can also change the isoelectric points (IEP) of the two powders to lower pH value. The potential and sedimentation tests indicate that the stable suspensions are prepared when pH is between 8 and 10. The viscosity measurements showed that there exists an optimum dispersant content for each suspension. The lowest viscosity can be obtained at the optimum dispersant content. The solid content of the stable micrometer TZP-YSZ suspensions can reach as high as 50vol%.
<001> Textured Pb(Mg1/3Nb2/3)O3–PbTiO3 Ceramics Prepared by Reactive Templated Grain Growth
Authors: Liu Dan , Yan Yong Ke , Zhou He Ping
Published: March 2009

<001> textured Pb(Mg1/3Nb2/3)O3-0.325PbTiO3 (PMN-32.5PT) ceramics were prepared by
reactive templated grain growth (RTGG). Plate-liked {001}-SrTiO3 single crystal particles were used as
template seeds. MgNb2O6, TiO2, PbO were mixed with SrTiO3 templates as a reactive matrix. SrTiO3
templates were oriented after tape-casting. The textured PMN–32.5PT ceramics were produced after heat
treatment. In preparing textured PMN-32.5PT, RTGG was more efficient than TGG because of the
chemical energy released in reaction. The final texture degree was very sensitive to the sintering history.
An initial anneal step below the melting point of PbO resulted in better development of texture.
The Influence of La2O3 Additive on the Dielectric Properties of Ba0.6Sr0.4TiO3-MgO Bulk Ceramics
Authors: Xu Chun Lai , Zhou He Ping
Published: March 2009

The influence of La2O3-doping on the dielec- tric properties of Ba0.6Sr0.4TiO3-6wt%MgO was
studied. With the increase of La2O3-doping content, the space between adjacent parallel crystal planes of
BST-MgO composite first became larger, then smaller. Proper quantity of La2O3 could ensure moderate
dielectric constant and reduce the dielectric loss of BST-MgO composite at high frequency, but excess
quantity of La2O3 would lower dielectric constant. When the La2O3-doping content was 0.2wt%, the
dielectric constant and loss of BST-MgO composite were equal to 93.2 and 0.005 (1MHz), respectively.
And the dielectric constant tunability could be obtained to 12.1% (21kV/cm).
Quantitative Evaluation for New Bone Growth of Bone Repairing Biomaterial Based on Color Image Segmentation
Authors: Hua Ya Hui , Wang Tian Fu , Zhou Da Li , Li De Yu , Lin Jiang Li , Zheng Chang Qiong
Published: March 2009

Quantitative evaluation of repairing effect of bone grafting material is one of the essential
studying subjects. However, traditional evaluation methods are subjective and qualitative. In this paper,
the region of new bone from a bone repairing biomaterial planted image is extracted based on color image
segmentation and then statistically analyzed to evaluate the property of bone grafting material
quantitatively. HSI color model, which corresponds with people’s vision system for color is used to
achieve ideal segmental results and effective utilization of color information. The S and I variable are
used as thresholding condition for image segmentation, thereby obtaining the area of new bone. The effect
of BMP contained in BMP/α-TCP is estimated furthermore. Experimental results show that the composite
BMP/α-TCP induce more bone than pure α-TCP in virtue of BMP. This study provides theoretical and
experimental suggestions for clinical applications of BMP/α-TCP.
Preparation of Yellow Color Pearlescent Pigments of CeO2-Mica
Authors: Zhong Sheng Wen , Zhang Qian , Zhang Shu Jin , Han De Qiang , Kuang Jing Zhong
Published: March 2009

A wet-chemical deposition method was developed to synthesize CeO2-mica pearlescent pigment using CeO2 as the coating material and mica as the base material. The main factors affecting the synthesis processes were studied. The optimum conditions were obtained were as: the coating reaction temperature is 70 ~ 80°C, cover ratio is 30 ~ 40%, stirring velocity is about 170 r/min, pH value is 6.50 ~ 7.50, heating rate is 3 ~ 5°C/min and heat treatment temperature is 800°C. The crystal phases and the microstructure of the pearlescent pigment powders were also analyzed by DTA-TG, XRD and SEM.
Preliminary Analysis of the Citations to Articles Published in Two Academic Journals
Authors: Zhou Rong , Wang Hua
Published: March 2009

The citations to articles published in Applied Physical Letters (APL) and Journal of the
American Ceramic Society (JACS) were analyzed. For each journal, 199 articles published in 1995 were
randomly selected and the number of citations in each year, CY, to these articles during 1996 ~ 2004 were
recorded. It was found that CY reaches its maximum in 1997 for APL and in 1999 for JACS. During the
first three years after the year when the articles were published, the number of self-citations to the articles
published in APL is about two times of that in JACS. These results seem to indicate that the impact factor,
which is defined as the ratio of the number of citations to a journal to the number of articles published in
this journal over a two-year period, is not comparable for different journals in different fields.
Microstructure and Mechanical Properties of Freeze Cast Alumina/Silicon Carbide Layered Composites
Authors: Yang Tae Young , Lyu Seung Woo , Park Young Min , Yoon Seog Young , Stevens Ron , Park Hong Chae
Published: March 2009

Symmetric three-layer composites prepared by sintering freeze cast compacts of alumina with additions of nanoparticle/whisker SiC, in 1-atm nitrogen at 1700-1800oC have been characterized in terms of microstructure and mechanical properties. Additions of SiC to Al2O3 result in improvement in toughness. In such cases, however, the reduction in strength at small flaw sizes must be overcome. Contact damage resistance is greatly increased in layered composites compared with monolithic composites, possibly due to redirection of indentation flaws along the layer interface.
A New Silver-Based Graded Composite as Electrical Contact Material
Authors: Wang Lu , Zhao Yong , Zhu X.T. , Wang Y.
Published: March 2009

Silver metal oxides (Ag/MeO) are extensively used as electrical contact materials in switching systems. A contact material with ideal operating parameters is very difficultly fabricated by conventional manufacturing techniques. In this paper, a new electrical contact material characterized by graded distributions of different oxides in Ag matrix was fabricated in order to optimize the distributions of operating parameters in material bulk instead of to enhance synchronously properties of that on contact surface. Two selected metal oxides, NiO and SnO2, were doped into Ag matrices, of which one surface layer NiO 12wt% was doped and another SnO2 12wt%, and the concentrations of NiO and SnO2 were varied gradually in bulk. The electrical contact test results show that the average operating number of NiO doped surface layer of graded Ag composite as contact surface is 4600 under 20A current and 220V AC voltage without melted welding while that of samples doped uniformly with NiO is 2200 under the same testing conditions. However, the average loss of mass due to arc erosion of graded samples is higher than that of uniform samples. We conclude that the functionally graded material (FGM) concept has potential application for electric contact materials.
Fabrication and Characterization of Ceramic/Metal Gradient Thermal Barrier Coating
Authors: Xiao Jin Sheng , Hu Chun Zhi , Zhao Wen Hua , Fu Wei Biao
Published: March 2009

Four Coating schemes and two substrate materials are designed to evaluate the characteristics of the ceramic/metal gradient thermal barrier coating. The gradient coating is successfully prepared by plasma spray with single torch and single feeder. The coating performance is evaluated by observing microstructure, measuring thermal shock resistance and thermal residual stress. The coating microstructure is observed by scanning electron microscope (SEM). Diffractive peaks for the gradient coating are got at different zone by X-ray spectroscopy (XRS). The thermal shock experiment shows that the thermal shock resistance property of the gradient coating is better than that of the non-gradient coating. The measurements of thermal residual stresses in different coating schemes are carried out by hole-drilling method, the results show that compressional stress presents on 1Cr18Ni9Ti substrate and tensile stress presents on 2Cr13 substrate.
Effect of V2O5 Addition on the Microwave Dielectric Properties of Ba(Mg1/3Nb2/3)O3 Ceramics
Authors: Shan Liu , Pan Wei
Published: March 2009

The effect of V2O5 as additives of different content on the densification, microstructure and
dielectric properties of Ba(Mg1/3Nb2/3)O3 (BMN) was investigated. The sintering temperature of the
V2O5-doped BMN samples were lowered down to 1250 oC with 0.5wt% V2O5 compared to pure BMN
ceramics where the sintering temperature was 1500 oC at least. The εr and τf was not influenced much,
while the Q value was affected by the sintering temperature and the V2O5 additives. The Q value
decreased with decrease of the sintering temperature and the V2O5 addition increasing due to the bulk
density and the second phase. Good microwave dielectric properties of Q·f=42100GHz, εr =31.7 and
temperature coefficient of resonance frequency (τf) =22.7ppm/ oC were obtained with 0.25 wt% V2O5
sintered at 1350 oC for 4h.
Resonant Modes of Piezoelectric Disc Structure and their Application in Micro Ultrasonic Motors
Authors: Ma Long , Chu Xiang Cheng , Li Long Tu , Yuan Song Mei
Published: March 2009

This article describes out-of-plane resonant modes of a piezoelectric disc structure. A new type of micro ultrasonic motor using the resonant mode B11 (Bmn, where m is the number of nodal circles, n is the number of nodal diameters) has been studied. The motor is a wobble-type motor. The stator of the motor uses this structure, consisting of a hollow metal cylinder and a piezoelectric ceramic disc bonded with a metal one, which is excited in the vibration mode by two electrical signals. The stator exhibits wobble displacement and transfers rotation to a rod rotor by the cylinder. The behavior of the stator has been simulated by the finite element analysis. The simulation results have been checked with laser scanning by a laser scanning vibrometer. The article closes with the introduction of the new micro ultrasonic motors based on this vibration mode with high rotation speed.
Novel Catalytic Electrodes for High Performance Solid Oxide Fuel Cells Operated at Intermediate Temperatures
Authors: Zhu Bin , Liu Xiang Rong , Cheng Ye , Zhang Mi Lin
Published: March 2009

The all-ceria-composite ITSOFCs have demonstrated extraordinary fuel cell performances since the ceria-composite electrodes are very catalytic and conductive, and the ceria-composite electrolytes are highly conductive and also electrolytic, in addition to excellent compatibility between the electrolyte and electrodes based on the same ceria-based composite materials. The power density outputs from 200 to 800 mWcm-2, were obtained for temperatures between 400 and 700°C. The maximum power density 0.72 Wcm-2 (1500 mAcm-2) at 600°C and 0.82 Wcm-2 (1800 mAcm-2) at 700°C were achieved, respectively. These highly catalytic electrodes functioned extensively for many different fuels, such as hydrogen and hydrocarbon fuels, e.g., natural gas, coal gas, methanol and ethanol etc. In some special cases, the ITSOFCs with the ceria-composite electrodes could also work at as low as 200°C. All these good performances are based on the novel catalyst function of the ceria-composite electrodes and internal reforming mechanism.
Dielectric Properties of (Bi1/2Na1/2)TiO3-SrTiO3 Ferroelectric Ceramics
Authors: Liu Chao , Qu Yuan Fang , Han Feng Long , Li Yuan Liang , Li Xiao Yan
Published: March 2009

Ferroelectric properties of (Bi1/2Na1/2) TiO3-SrTiO3 were studied. The dielectric properties
were measured at 1KHz. It was found that the dielectric constants are improved with the increase of
additive amount of BNT. If the amount continues increasing, the properties become worse, the
optimum dielectric constant of the samples can reach 4300. When the proportion of (Bi1/2Na1/2)TiO3:
SrTiO3 is 65:35, with the increase of additive amount of MnCO3, the Curie temperature descends
obviously. The dielectric constant increased at beginning and dropped sharply when the amount of
MnCO3 exceeds 1.1wt%.
Optical Property of Spark Plasma Sintered Translucent AlN Ceramics
Authors: Xiong Y. , Fu Zheng Yi , Wang Hang
Published: March 2009

Translucent AlN ceramics were fabricated using spark plasma sintering (SPS) technique with 3wt% CaF2 as sintering additive. The samples achieved 52.4% maximum transmittance in medium IR region after 10 min holding time by spark plasma sintering at 1800°C and 30 MPa pressure in N2. The results from XRD, SEM, TEM and EDX showed that the sintered bodies were densely compacted and highly pure with fine grain size and uniform microstructures. No secondary phases were observed at the grain boundaries and triple grain junctions, which guaranteed good optical property of the sintered bodies.
Luminescence Properties of Spherical Phosphors SrSiO3:Eu3+
Authors: Han Xiu Mei , Lin J. , Yu M. , Lin C.K. , Qi Xi Wei , Yu Zhi Yong , Wang Xiao Qin
Published: March 2009

Spherical SiO2 particles have been successfully coated with SrSiO3:Eu3+ phosphor layers through a sol-gel process. The resulted core-shell phosphors were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence spectra as well as kinetic decays. The XRD results demonstrate that the SrSiO3:Eu3+ layers begin to crystallize on the SiO2 particles after annealing at 1000oC. The obtained core-shell phosphors have perfect spherical shape. The Eu3+ shows a strong photoluminescence (PL) (dominated by 5D0-7F2 red emission at 612 nm).
Microwave Synthesis of BaTiO3 from BaCO3 and TiO2
Authors: Liu Yan Yi , Pan Wei
Published: March 2009

BaTiO3 powder was synthesized from BaCO3 and TiO2 using a domestic microwave oven. The
samples were synthesized under different temperatures with various holding times. X-ray diffraction
(XRD) and scanning electron microscopy (SEM) were used to examine the phase compositions and
morphologies of the result samples. The main phase obtained at 950°C was BaTiO3, and the intermediate
phases Ba2TiO4 and Ba4TiO9 were also detected. The pure, well-crystallized BaTiO3 powder could be
obtained at 1050°C within 10 minutes and the particle size ranged from 300~500nm. In comparison with
conventional synthesis, faster speed and finer grains could be achieved through microwave heating.
Synthesis of La-Mn Substituted M-Type Ba Hexaferrites by Sol-Gel Method
Authors: Han Zhi Dong , Dong Li Min , Wu Ze , Shan Lian Wei , Zhang Xian You
Published: March 2009

BaFe12O19 and La-Mn substituted M-type Ba hexaferrites were synthesized by sol-gel method and characterized by XRD, SEM and FTIR. The results showed that citric acid played an important role in the forming process of BaFe12O19. BaFe12O19, synthesized under lower citric acid and presintered at 450°C, showed improved hexagonal crystal phase. BaLa0.5Fe11.5O19 and Ba(MnLa)0.5Fe11O19 showed similar crystal structure to BaFe12O19 while Ba0.5Mn0.5Fe12O19 and Ba0.5Mn0.5La0.5Fe11.5O19 showed changed crystal constant. FTIR analysis proved the formation of new mental-oxygen bond in substituted hexaferrites.
Improved Electrodeposition of CuIn1-xGaxSe2 Films
Authors: Long Fei , Li Jian Jun , Gu Tao , Zou Zheng Guang
Published: March 2009

CuIn1-xGaxSe2(CIGS) precursor films are fabricated on Mo foil by coelectrodeposition. The influence of the applied potential and the electrolyte additive in the process of electrodeposition are discussed. The precursor films are annealed in Ar for a short time to synthesize the polycrystalline thin film. The annealed layers are only phase-pure CuIn0.7Ga0.3Se2 and show a good crystallinity.
Na-Site Doping of NaCo2O4 Thermoelectric Materials
Authors: Li Ying , Zhang Li Hua , Wang Shu Lan , Xu Gui Ying , Jiang Mao Fa
Published: March 2009

The K, Ca, Sr and Ce doped and non-doped γ-NaxCo2O4 samples were prepared by the solid-state reaction method. Results show that the Na-site doping might lead to an increase in the Seebeck coefficient and a decrease in the electrical conductivity of the samples. The maximum power factors of the K, Ca and Sr doped samples are respectively 2.04, 1.93 and 1.9 W·m-1·K-2, corresponding to an increase by 58%, 50% and 47% compared with that of the non-doped samples. Thus, the Na-site doping can improve the thermoelectric properties of γ-NaxCo2O4 oxides.
Modulated Structure of Bi1.8Sr2.0Rh1.6Ox
Authors: Yubuta Kunio , Okada Satoshi , Miyazaki Yuzuru , Terasaki Ichiro , Kajitani Tsuyoshi
Published: March 2009

We have investigated the modulated structure of the misfit-layered crystal Bi1.8Sr2.0Rh1.6Ox by
means of electron diffraction and high-resolution electron microscopy. This compound consists of two
interpenetrating subsystems of a hexagonal RhO2 sheet and a distorted four-layered rock-salt-type
(Bi,Sr)O block. Both subsystems have common a-, c-axes and β-angles with a = 5.28 Å, c = 29.77 Å and
β = 93.7º. On the other hand, the crystal structure is incommensurated parallel to the b-axes, among which
b1 = 3.07 Å for the RhO2 sheet and b2 = 4.88 Å for the (Bi,Sr)O block. The misfit ratio, b1/b2 ~ 0.63,
characterizes the structural analogue as [Bi1.79Sr1.98Oy]0.63[RhO2]. This compound has two modulation
vectors, i.e., q1 = – a* + 0.63b1* and q2 = 0.17b1* + c*, and the superspace group is assigned as the Cc(1β0,
0μ1)-type from the electron diffraction patterns. High-resolution images taken with the incident electron
beam parallel to the a- and c-axes clearly show displacive as well as compositional modulations.
The Influence of Oxygen on the Electrical Properties of Bulk and Thin Films of PbTe Semiconductors
Authors: Kreizman R. , Traistman N. , Shaked M. , Dashevsky Z. , Dariel M.P.
Published: March 2009

PbTe based semiconductors are characterized by a narrow energy gap and can be used for IR
detectors, light emission diodes, lasers and thermoelectric devices. The objective of the present work was
to study the effect of oxidation on the properties of n- and p-type PbTe samples prepared by powder
metallurgy (bulk materials) and physical vapor deposition (thin films with thickness ∼1 μm). The samples
were characterized by SEM, AES and XRD. The Hall effect and electrical conductivity of PbTe samples
have been examined over the 80 – 300 K temperature range. The experimental results are accounted for in
the framework of a model that is based on: 1- the fast diffusion of oxygen along grain boundaries (GB); 2
- oxygen absorption that generates acceptor states at GB (short time annealing) and the growth of PbTe
oxides on GB with properties corresponding to wide band semiconductor (lengthy annealing); 3 - the
creation of potential barriers on GB due to oxidation with a thermally activated dependence of the
conductivity.
Fabrication and Characteristics of Al2O3/Cu Composite Particles by MA & PCS
Authors: Wang Fu Xiang , Gai Guo Sheng , Jia Cheng Chang
Published: March 2009

This paper describes a dry composite process, in which fine α-Al2O3 ceramic guest particles
with a mean size of 150 nm were mechanically compounded with metal Cu host particles with a mean size
of 25 μm by embedding and curling the guest particles on the surface and inside of host particles using
mechanical alloying (MA) and micron/nano particles composite system (PCS). The optimum rotor speed
and processing time were determined according to the treatment effect under different conditions.
Particles size and other features were investigated. Particles size decreased quickly, and bulk density and
tap density of the composite particles increased noticeably under appropriate process conditions.
Al2O3/Cu composite material was fabricated via using hot-press sintering technique in argon shield.
Microstructure of the composite material was studied by SEM, and the results have shown that a-Al2O3
particles distribute evenly in Al2O3/Cu composite material, which also proved that Al2O3/Cu composite
particles could be fabricated perfectly by MA & PCS.
Preparation of Ultrafine β-Sialon Powder by Citrate Sol-Gel and Carbothermal Reduction Nitridation
Authors: Zhang Hai Jun , Zhang Hai Tang , Miao Jin Qi , Wang Zi Liang , Jia Quan Li , Jia X.L.
Published: March 2009

Ultrafine β-sialon powder is synthesized by citrate sol-gel and carbothermal reduction and nitridation (CRN) process. The presence of small amounts of β-sialon as crystal seed can obviously accelerate the formation of final β-sialon product and lower its formation temperature. The effects of nitriding temperature on the formation of the final β-sialon are investigated. The mean particle size of the prepared β-sialon powder is 100 ~ 150 nm. The β-sialon precursor gel and the ultrafine β-sialon powder are characterized by XRD, TG-DTA and SEM. The isoelectric point of ultrafine β-sialon is pH 2.46.
Application of Acetate Starch to Colloidal In Situ Consolidation Molding Process of Alumina Ceramic
Authors: Li Xiao Xi , Chen Ling , Ye Jian Dong , Li Lin , Huang Yan Ran
Published: March 2009

A new consolidation in-situ forming process for high-performance alumina ceramic using acetate starch was investigated. The pasting behavior and thermogelling properties of acetate starch and the effects of different amount of acetate starch and solid loading on the rheologic behavior of the ceramic slip, as well as the linear shrinkage, density, strength and microstructure of the green body were discussed. The results indicate that acetate starch paste has good thermal stability and gelling ability. When the content of acetate starch is about 0.5%~1.5% (mass fraction), the apparent viscosity of alumina slurry, which is always less than 1Pa·s even for 58% (volume fraction) dense suspension, increased with increasing the acetate starch content and solid loading. That results in easier to cast. Moreover, with the increasing of solid loading the linear shrinkage and dry strength of green bodies decreased and the relative density increased. With the increasing starch content, the linear shrinkage rate and the density of the dried body decreased, while the strength of the dried body almost linearly increased. The green body with homogeneously-distributed density and pore size was also obtained in this work. It is concluded that Al2O3 ceramics can be consolidation in-situ formed based on the gelling network of thermally swelled and gelatinized acetate starch.
Predictive Model of Surface Roughness in High-Speed End Milling Process by Factorial Design of Experiments
Authors: Wang Su Yu , Ai Xing , Zhao Jun
Published: March 2009

Predictive models are presented for the surface roughness in high-speed end milling of 0.45%C steel and P20 die-mould steel based on statistical test and multiple-regression analysis. The data for establishing model is derived from experiments conducted on a high-speed machining centre by factorial design of experiments. The significances of the regression equation and regression coefficients are tested in this paper. The effects of milling parameters on surface roughness are investigated by analyzing the experimental curves.
Surface Optimizing Behaviour of Nano-Cu Lubricant to Tribosurfaces by Mechanochemical Process
Authors: Shi Pei Jing , Xu Bin Shi , Xu Yi , Liu Q.
Published: March 2009

A special kind of surface modified copper nanoparticles was selected as the
auto-reconditioning materials to in situ generate a copperized protective film on iron-base metal
surfaces under designed tribological conditions. The morphologies and element distributions of the
formed film were observed and determined by scanning electron microscopy (SEM) and energy
dispersive spectrometry (EDS). The micro mechanical properties and tribological behaviors were
investigated by nano test system and ball-on-disc tribotester. The results show that the morphology
of the protective film is smooth, the nano-hardness decreases by 46% and the friction coefficient of
the copperized protective film is about 0.10. The forming mechanism of the auto-reconditioning
film can be described that the copper nanoparticles deposit on the worn surfaces and form
iron-copper alloy film with lower hardness and shear strength, which has better friction-reducing,
antiwear and surface-optimizing behaviors.
Study on High Precision and Super-Slow Speed Feeding Table for Micro-EDM Machining
Authors: Liu Xiang Yang , Yu D.W. , Cai X.J. , Huang H.
Published: March 2009

A feeding table system is set up to meet the need for high motional precision and
super-slow speed in micro-electron discharge machining (micro-EDM). It is composed of a resonant
piezoelectric ceramics motor, a linear bearing and a linear encoder . It features high accuracy due to
the application of linear driving, closed-1oop feedback and elimination of abbe’s errors. The
characteristics of fine motion , slow speed and load capability are investigated. The results of the
experiments show that the stable fine motion of this system can be as little as 100 nanometer and its
speed can be as slow as 0.5 micron per second which is proper for feeding table of micro-EDM.
Effect of Nanostructured TiH2 on the Formation of Multimeshworked and Nanoporous TiO2 by Cathodic-Anodization Treatment
Authors: Chen Chin Sheng , Cheng H.C. , Lee S.Y. , Chan Chaung Chih , Ou K.L.
Published: March 2009

Cathodic-anodization process was performed to treat titanium sheets to improve biocompatible performance. Grazing incident X-ray diffraction, transmission electron microscopy, scanning electron microscopy and electrochemical measurement were used to evaluate the influence of hydrogen on the formation of nanoporous TiO2. Multimeshworked and nanoporous TiO2 was observed after treatment with cathodic-anodization process. The nanoporous oxide layer is hard to form without nano-TiH2. The nano-TiH2 plays an important role in forming multimeshworked and nanostructured TiO2 layer. Hydrogen charging by cathodization is believed to enhance the formation of nanoporous oxide film and thus promote biocompatibility.
Optimal Generation of Cutter Path in the Form of Polar Coordinate for NC Machining of Noncircular Contours
Authors: Qiu Hua , Kubo A. , Li Zi Ye , Lin Chao
Published: March 2009

This paper proposes an optimal interpolation approach to generate cutter paths in the
form of polar coordinate for machining noncircular contours. The cutter path obtained with the
approach consists of a series of Archimedes’ spiral segments and the number of segments is the
fewest under the condition that the interpolation error completely satisfies the specified limit value.
It can be also evidenced that the profile error of the machined contour due to the cutter path is
perfectly controlled within the specified interpolation accuracy limit. The result of applying the
approach to the contour machining of a disc cam sufficiently illustrates the effectiveness of the
proposed approach.
Implicit Formulation of Homogenization Method for Periodic Elastoplastic Solids
Authors: Asada Takashi , Ohno Nobutada
Published: March 2009

In this study, to determine incremental, perturbed displacement fields in periodic
elastoplastic solids, an incremental homogenization problem is fully implicitly formulated, and an
algorithm is developed to solve the homogenization problem. It is shown that the homogenization
problem can be iteratively solved with quadratic convergences by successively updating strain
increments in unit cells, and that the present formulation allows versatility in the initial setting of
strain increments in contrast to previous studies. The homogenization algorithm developed is then
examined by analyzing a holed plate, with an elastoplastic micro-structure, subjected to tensile
loading. It is thus demonstrated that the convergence in iteratively solving the homogenization
problem strongly depends on the initial setting of strain increments in unit cells, and that quick
convergences can be attained if the initial setting of strain increments is appropriate.
Effects of Strain Rate and Temperature on Yield Locus for AZ31 Magnesium Alloy Sheet
Authors: Naka Tetsuo , Hayakashi Masanori , Nakayama Yasuhide , Uemori Takeshi , Kohzu Masahide , Higashi Kenji , Yoshida Fusahito
Published: March 2009

The yield locus of type AZ31 magnesium alloy sheet was obtained by performing biaxial
tensile tests, using cruciform specimens, at temperatures of 100, 150, 200, 250 and 300 P
o
PC at strain
rates of 10P
-2
P, 10P
-3
P and 10P
-4
PsP
-1
P. Based on the experimental results, the effects of strain-rate and
temperature on the yield locus was discussed. The size of yield locus drastically decreased with
increasing temperature and decreased with decreasing strain-rate. Neither von Mises’s criterion or
Hill’s can well predict the shape of the yield locus of this sheet metal. Instead of these quadratic
yield functions, the yield criterion of Logan-Hosford or Barlat is a better choice for the accurate
description of biaxial stress-strain responses at high temperature.
Influence of Strain Ratio on Bending Fatigue Life in TiNi Shape Memory Thin Wire
Authors: Matsui Ryosuke , Tobushi Hisaaki , Makino Yoshiyasu
Published: March 2009

In this study, we performed the bending fatigue test and investigated the influence of
strain ratio on fatigue life in TiNi shape memory thin wire. The pulsating plane bending, alternating
plane bending and rotating bending fatigue tests were carried. Additionally, we carried out the
observation of the fatigue fracture surface by a scanning electron microscope. The behavior of
fatigue crack was investigated. The results obtained are summarized as follows. (1) The martensitic
transformation (MT) stress of the superelastic thin wire (SE-NT) is higher than that of the SMA thin
wire (SME-NT) and the fatigue life of SE-NT is shorter than that of SME-NT. Maximum bending
strain at the fatigue limit is the MT starting strain. (2) The low-cycle fatigue life curve in plane
bending for SE-NT is expressed by a power function of maximum strain εmax and the number of
cycles to failure Nf. The smaller the strain ratio for the same εmax, the shorter the fatigue life. (3) In
both the rotating bending and the plane bending, fatigue cracks nucleate on the surface of the wire
and one fatigue crack grows preferentially. The region in which fatigue crack propagated is
fan-shaped.
A Numerical Investigation of Interface Dynamics during Martensitic Transformation in a Shape Memory Alloy Using the Level-Set Method
Authors: Iwamoto Takeshi , Cherkaoui Mohammed , Busso Esteban P.
Published: March 2009

In this study, the simulation of the motion of an interface during the stress-induced
martensitic transformation of a shape memory alloy is performed using the level-set method. The
kinetics of the phase transformation is defined as an anisotropic kinetic relation between the rate at
which the weak discontinuity moves, given by its normal velocity, and the thermodynamics driving
force. The latter is derived from a dissipation function, which obeys the 1st and 2nd law of
thermodynamics and accounts for large strains. Furthermore, a hyperelastic constitutive framework is
used to describe the constitutive behavior of the material. The model is implemented into the finite
element method and is then used to solve a 2D phase transformation problem in a shape memory
alloy.
Inelastic Behaviour of Concrete/Steel Composite Beam in Fire
Authors: Wong M. Bill
Published: March 2009

The configuration of a steel beam in a concrete/steel composite floor in fire gives rise to a
non-uniform temperature profile across the depth of the cross-section. This temperature profile
affects the deflection of the steel beam in two ways: thermal bowing due to non-uniform thermal
strains and beam deflection due to imposed loads. The beam deflection becomes larger as the elastic
properties of the steel beam deteriorate when the temperature is rising. The deflection increases
rapidly when the cross-section of the steel beam starts to yield. This paper presents a method for the
calculation of the total deflection of a steel beam in a steel/concrete composite floor in fire when the
beam is loaded beyond its elastic limit. In this study, the steel beam is assumed to support the
concrete floor slab simply at its ends without composite actions.
Stability Analyses of the Three Gorges Dam Foundation against Sliding by Strength Reduction of Finite Elements
Authors: Hou Ming Xun , Ge Xiu Run
Published: March 2009

This paper studies the dam foundation stability of the representative no. 3 powerhouse-dam
section of the Three Gorges Dam (TGD), China, using elastic-plastic finite element shear strength
reduction technique. In the no. 3 powerhouse-dam section area, the low-angle discontinuities, such as
joints and faults, are mostly developed in the dam foundation rock mass, and constitute deep
foundation stability problems. These weak structure planes affecting the dam foundation stability are
modeled as continuum bodies in the finite element modeling according to their respective spatial
geometrical characteristics including inclination and dip angle. Three-dimensional elastic-plastic
finite element analyses are performed to obtain the stress and deformation distributions of TGD
foundation and concrete structures. The factor of safety (FOS) of TGD foundation stability against
sliding and its failure mechanics are comprehensively evaluated with the following criteria: (a) The
maximum of the trial factors of shear strength reduction can be reached by which the dam foundation
is brought to the critical equilibrium state; (b) The inflection points of the curves of the displacements
of dam heel, dam toe and dam top, vs. the trial factors of shear strength reduction are located; and (c)
Plastic zones develop along the potential sliding paths consisting of the dam heel, long and large
joints, and other weak structure planes as the trial factors increase. The results obtained show that the
dam foundation of the no. 3 powerhouse-dam section is stable under the designed normal load
combinations. The evaluations of the FOS of dam foundation stability presented may provide a
significant reference for the safety assessment of TGD in the Three Gorges Project, China.
Pattern Shifting Analyses of Micro-Structures of IC Package
Authors: He Yu Ting , Shi Rong , Li Hong Peng , Li Feng , Zhang G.Q. , Ernst L.J.
Published: March 2009

Pattern shift is one of the main failures of micro-electronics. In this paper, the influence of
plastic deformation values of micro-structures of IC packages on the pattern shift of metal lines is
studied by maximum plastic strain theory using a certain 2D FEM model with different design
parameters, “d”, “w”, “t_epo”, “t_Teos”, “t_glue” “sy_glue” and “sy_al”. For different critical
process step, the final process temperature is acted as a representative parameter to analyze its impact.
Furthermore, Response Surface Model (RSM) of plastic strains is established using any two design
parameters. Results show that “w”, “t_epo”, “t_Teos”, “t_glue” “sy_glue” and “sy_al” will have
different influence on pattern shifting while “d” have little impact.
Geometrical Similarity of Thermo-Structural Problems
Authors: Chen F.L. , Hu P. , Yu T.X.
Published: March 2009

This paper is concerned with the geometrical similarity of heat conduction-elastioplastic
structural problems. When the dimensions of a structure are geometrically scaled down/up, the
similarity relations for both isolated heat conduction and elastoplastic structural problems are
derived. For cases of thermo-structural coupled, it is concluded that heat conduction-static
elastoplastic problems can be geometrically similarly scaled down/up and a set of similarity
relations are drawn accordingly. As examples, a full-, half- and quarter-scale unilaterally-tensioned
plate and internally-pressured cylindrical shell irradiated by a laser pulse are numerically analysed
and the numerical results have confirmed this conclusion. However, heat conduction-dynamic
elastoplastic problems are found not to comply compatibly with the geometrically similar scaling.
Proposal of Various Connecting Methods of Fiber Strands and Finite Element Method Analysis of Strength
Authors: Higuchi Rie , Kanno Yoshinori
Published: March 2009

The main purpose of this study was to investigate the strength and performance of CFRP
by using simple fiber-reinforced methods. It shows that the Reef knot has the highest strength in all
by an uni-axial loading test. It is confirmed that the outer shape of the CFRP is important to
fabricate the strongest structure. It is also attributed that the CFRP joining methods with a smooth
contour will improve the connection strength between fiber strands and knot.
Higher-Order Stress due to Self Energy of Geometrically Necessary Dislocations
Authors: Ohno Nobutada , Okumura Dai
Published: March 2009

The self energy of geometrically necessary dislocations (GNDs) in single crystals is
considered to inevitably introduce a higher-order stress as the work conjugate to slip gradient. It is
pointed out that this higher-order stress changes stepwise in response to in-plane slip gradient and
thus explicitly influences the initial yielding of polycrystals. The self energy of GNDs is then
incorporated into the strain gradient plasticity theory of Gurtin (2002). The resulting theory is applied
to 2D and 3D model crystal grains of diameter D, leading to a D-1-dependent term with a coefficient
determined by grain shape. This size effect term is verified using published experimental data of
several polycrystalline metals. It is thus found that the D-1-dependent term is successful for predicting
not only the grain size dependence of initial yield stress but also the dislocation cell size dependence
of flow stress in the submicron to several micron range of D.