bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Charge-Discharge Characteristics of Polycrystalline LiNi1-xCoxO2 (0 ≤ x ≤ 0.5) as a Cathode Material for Lithium Rechargeable Batteries
Authors: Li Xin Lu , Kang Fei Yu , Shen Wan Ci , Shi Xiu Juan
Published: March 2009

The synthesis and electrochemical characteristics of LiNi1-xCoxO2 (0 £ x £ 0.5) used as the promising cathode materials for lithium rechargeable batteries were investigated. The LiNi1-xCoxO2 was prepared by a soft chemistry route in which citric acid was used as the chelating agent to make the sol-gel precursor, then was calcined in oxygen atmosphere at the calcination temperature of 800°C for 12 h.
Polycrystalline LiNi1-xCoxO2 possesses a hexagonal lattice of the α-NaFeO2 type characterized by using X-ray diffraction. The discharge capacity of LiNi0.8Co0.2O2 was 169.1 mAh/g with the efficiency of 90.5% in the first cycle and 162.1 mAh/g with only 4% capacity fading in the 10th cycle at 0.2 C rate over a potential range of 3.0-4.2 V.
The Effect of 'Hydrogenation – Recalcination' Cycling on the Magnetic Properties of Strontium Hexaferrite
Authors: Seyyed Ebrahimi S.A.
Published: March 2009

Strontium hexaferrite powder synthesized conventionally was treated in a hydrogen atmosphere and then recalcined in air. This process had a marked effect on the microstructure and on the magnetic properties of the initial sample. The process was repeated several times and the effects investigated. The results showed that the products of the treatment prior to recalcination are Fe and Sr7Fe10O22 and this
resulted in a change in magnetic properties from hard to soft. Consequent calcination, resulted in the reformation of strontium hexaferrite but now with a much finer grain size. This resulted in a significant enhancement of the coercivity. The variation of the coercivity with the number of cycles indicated a maximum value of 413 kA/m which then remained constant with subsequent cycling.
Chemical Solution Deposition Growth of La0.7Ca0.3MnO3 Films and their Electric Pulse Induced Resistance Change Effect
Authors: Dong Rui , Wang Qun , Chen Li Dong , Li Xiao Min
Published: March 2009

A simple chemical solution deposition method was developed for the preparation of
La0.7Ca0.3MnO3 (LCMO) thin films. The LCMO thin films were prepared on Si/SiO2/TiO2/Pt substrates by spin-coating method, followed by heat-treatment at 900°C. The fabrication process of the LCMO thin film was investigated by means of TG-DSC, FTIR, XRD, FE-SEM and EPMA. The electric pulse induced reversible resistance switching is observed in the Ag-LCMO-Pt sandwich structure.
Mechanism of the Acicular Nanosize Mg,Al-Hydrotalcite Grain Growth under Hydrothermal Conditions
Authors: Ren Qing Li , Luo Qiang , Chen Wei
Published: March 2009

The highly pure acicular nanosize Mg,Al-hydrotalcite was synthesized by the one-step liquid reaction method at atmospheric pressure. The favorable growth unit in the reaction liquid, the requirements of Al3+ entering the Mg2+-(OH-)6 octahedral and forming the growth unit M-(OH-1)6 (M=Mg2+, Al3+) and growth mechanism that the nanosize Mg,Al-hydrotalcite crystal embryo follows are
studied according to the test results of XRD, TEM, SEM and IR. Later, that the nanosize Mg,Alhydrotalcite crystal embryo growth follows the gathering growth theory was deeply investigated.
Sintering and Dielectric Properties of Nano-BaTiO3 Powder Synthesized by High-Gravity Reactive Precipitation
Authors: Liu Xiao Lin , Zhang Jing Qiang , Chen Jian Feng , Gao Li Jie , Wang Shao Qing
Published: March 2009

The dielectric properties and sintering activity of nano-BaTiO3 powders synthesized by HGRP method were investigated. The starting BaTiO3 powders were calcined at different temperatures from 700 to 900°C to improve their crystallinity and the mean particle size of BaTiO3 powders obtained increased
from 40nm to 80nm. After being formed by conventional dry pressing the green bodies were sintered at 1100°C and 1200°C for 2hr in air. The effects of both calcinating and sintering temperatures on the sinterability, dielectric property and microstructure of BaTiO3 ceramics were discussed. The experimental results showed that the BaTiO3 powders have high sintering activity and the highest
dielectric constant of this material at room temperature may reach 2880.
Development of 3D Ceramic Photonic Bandgap Structures
Authors: Yin Hai Qing , Kirihara Soshu , Miyamoto Yoshinari
Published: March 2009

The three-dimensional (3D) photonic band gap material is a material that there exists a full photonic band gap in which waves are forbidden to propagate whatever the polarization or the direction of propagation. In order to obtain photonic bandgap in lower range, we focus on the fabrication of PBG materials of diamond structure with TiO2 powder mixed with SiO2. The inverse epoxy structure with periodic diamond lattices in millimeter order has been fabricated by stereolithographic rapid prototyping. TiO2 slurry was filled into the epoxy structure and then cold isostatic pressing was applied. After sintering at 700K for 5hrs, the epoxy was burnt out and the designed structure was maintained perfectly. The calculated band diagram shows that there exists an absolute photonic band gap for all wave vectors. The
measurement of transmission from 10 to 20 GHz in <100> direction shows that a complete band gap is formed at about 14.7-18.5 GHz. The magnitude of the maximum attenuation is as large as 30 dB at 17 GHz.
Novel Process for Synthesizing Nano-Ceramics Powder: Mechanical & Thermal Activation Processing
Authors: Cui Xiao Long , Cui Li Shan
Published: March 2009

A novel process for synthesizing nano-ceramics powders, named Mechanical & Thermal
Activation Processing, is discussed in the present paper. Dissimilar with the tradition processing of
mechanical activation or mechanochemistry, the processing is based on thermal activation in liquid
phase (molten salt) after mechanical activation. The synthesizing of nanometer sized TiC particles by the method was investigated. The end product has been analyzed by X-ray diffraction (XRD),transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersion X-ray (EDX). The results show that nano-meter sized particles were formed, and the lattice parameter of TiC is close to the value of non-oxygen TiC. Compared with usually methods, the whole processing time needed is shortened; moreover, the synthesis temperature could be reduced 500°C. The mechanism for mechanical & yhermal activation is discussed.
Biomimetic Synthesis of CaCO3 Particles with Specific Size and Morphology
Authors: Yu Jia Guo , Yu Jimmy C.
Published: March 2009

Calcium carbonate particles with different morphologies were fabricated by the precipitation reaction of sodium carbonate with calcium chloride in the absence and presence of the copolymer poly(styrene-alt-maleic acid) (PSMA) at 80oC, respectively. The as-prepared products were characterizedwith SEM, XRD, Infrared and BET surface areas. The results showed that the pH of solution and the
concentration of PSMA and CaCO3 significantly influenced the morphologies of CaCO3 particles. Various crystal morphologies of calcium carbonate, such as plates, rhombohedras, rods, ellipsoids, dumbbells, peanuts, spheres etc., could be obtained depending on the experimental conditions.
Two Methods for the Measurement of Complex Permittivity of Microwave Dielectric Ceramics
Authors: Xiao F. , Chen R. , Huang Zhi Hong , Xiong Zhao Xian
Published: March 2009

Two measuring techniques, the parallel plate method and the cylinder cavity perturbation method, for complex permittivity of microwave dielectric ceramics were introduced. Attention was focused on the theoretical consideration of measurement precision and suitable applications of the techniques.
Preparation and Characterization of BaTiO3 Powders by Sol-Gel and BaTiO3 Ferroelectric Films by Electrophoretic Deposition Technique
Authors: Ma Ya Lu , Zhu Hong Long , Li Jian Lin
Published: March 2009

The clear and transparent sols of BaTi acetate were prepared from tetrabutyltitanate, barium acetate aqueous solution, ethanol and acetic acid. The BaTi acetate sols were transferred into gels by sol-gel process, and the gels were dried and calcined to nanostructured BaTiO3 powders. Pure barium titanate powders added in mixtures of acetone and iodine and water or acetylacetone (Acac) and ethanol (EtOH) as suspension systems, the aim of this study was to use the electrophoretic deposition technique (EPD) to fabrication the BaTiO3 ferroelectric films with high dielectric constant. During sol-gel transition process, it is found that the initial PH value of sol affected not only the sol-gel transition, but also the particles size of the final calcined BaTiO3 powders. The effects of the EPD process parameters such as the suspension, powder concentration, electrical field strength on the specific EPD deposited weight were investigated. The films sintered at 1050°C for 2h were crystallized into the tetragonal phase at room temperature, which were sufficiently dense and had uniform microstructure and excellent dielectric properties.
Characteristics of Sr2CeO4 Powder Phosphor Prepared by Combustion Route
Authors: Shi Shi Kao , Wang Ji Ye , Li Jun Min , Zong Rui Long , Zhou Ji
Published: March 2009

The precursor powder of Sr2CeO4 was prepared from a nitrate starting solution by a combustion route with urea as a fuel. Sintering the precursor powder at different temperatures for 6h, a blue-white emission phosphor was synthesized. The microstructure and photoluminescence studies of Sr2CeO4 compound are reported. The particle sizes of the powder phosphor are around 0.5-2 µm when heat treated between 9500C to 11500C and the emission spectrum exhibits a broad band
maximum at about 470 nm. The chemical purity and photoluminescence intensity of Sr2CeO4 powder phosphor strongly depend on the post-heat-treated temperature.
Preparation and Characterization of Semi-Conducting (Ba,Sr)TiO3 Powders by a Wet Chemical Route
Authors: Zheng Zhi Ping , Zhou Dong Xiang , Gong Shu Ping , Hu Yun Xiang , Huang Guo Hua
Published: March 2009

Ultrafine (Ba,Sr)TiO3-based powders used for making positive temperature coefficient of resistance (PTCR) were synthesized by two chemical steps: polyacrylamide gel process and liquid phase coating process. First, donor doped (Ba,Sr)TiO3 powders were synthesized by polyacrylamide gel process
at rather low temperature, and the physical and chemical characteristics of the gels and the precursorpowders were investigated by DSC, TG, XRD and TEM. Secondly, acceptor and sintering aid were coated by an aqueous solution containing acceptor (Mn) and additive (Si). The characterization and
sintering behavior of the semi-conducting powders and the PTC effect of ceramic samples prepared by the as-obtained powders were investigated.
Synthesis and Evaluation of Antibacterial Titanate Nanotubes
Authors: Ling Yun Han , Qi Jun Jie , Zou X.F. , Zhao X.M. , Bai Xin De , Feng Qing Ling
Published: March 2009

Antibacterial titanate nanotubes were synthesized by alkali digesting of metatitanic acid via hydrothermal route, following by cation-exchanged and immobilized with Ag+, Zn2+ and Cu2+. The conditions for nanotube synthesis and ion exchange were investigated; the microstructures of as-synthesized nanotubes were characterized by XRD, SEM, XPS and DTA/TG. The antibacterial performance of cation-doped titanate nanotubes was tested and evaluated by Escherichia Coli. and
staphylococcus aureus.
Low-Temperature Synthesis of Mono-Phase Ultrafine Yttrium Aluminum Garnet by Sol-Gel Combustion Process
Authors: Qiu Fa Gui , Pu Xi Peng , Zhang Rui , Guo Jing Kun
Published: March 2009

Ultrafine yttrium aluminum garnet (Y3Al5O12, YAG) powders were synthesized by sol-gel combustion process from a mixed solution containing aluminum and yttrium nitrates. The precursor and powders were characterized using X-ray diffraction, thermogravimetry-differential scanning calorimetry-mass spectrometry, and transmission electronic microscope. Mono-phase cubic powders were obtained at 900oC by directly crystallizing from amorphous materials and no intermediate phase was observed. The powders processed at 900oC were uniform and in good dispersity with average particle size of about 20 nm.
New Processing of Textured Ceramics by Colloidal Processing Under High Magnetic Field
Authors: Sakka Yoshio , Suzuki Tohru
Published: March 2009

The controlled development of texture is one of the ways for effective in improving the physical and mechanical properties. We’ll demonstrate new processing of textured ceramics as an example of alumina by slip casting in a high magnetic field and subsequent heating. Susceptibility of diamagnetic α-alumina is very small, but the orientation energy of alumina particle by a high magnetic field becomes larger than the thermal energy. α-alumina of a rhombohedral structure shows anisotropic
susceptibility, but this anisotropy has up to now been more or less ignored due to its very low value. However, in a high magnetic field the energy of crystal anisotropy becomes comparable to or larger than the energy of thermal motion. The degree of orientation depends on processing factors such as heating temperature, particle size, magnetic field and concentration of suspension, etc. This process technique
confers several advantages and it is possible for this type of processing to be applied to other non-cubic ceramics, such as TiO2, ZnO, SnO, HAP, AlN, SiC, etc.
Low Temperature Synthesis of Strontium Barium Niobate by Spark Plasma Sintering
Authors: Fang Ming Hao , Pan Wei , Fang Zhen Yi , Shi Sui Lin , Xu Qiang
Published: March 2009

Pure Strontium barium niobate, Sr0.5Ba0.5Nb2O6 (SBN50), was synthesized successfully by spark plasma sintering from two mixtures: SrCO3/BaCO3/Nb2O5 mixtures and the mixtures calcined at 800oC. The phase identification of the SBN crystalline grains was evaluated by X-ray diffraction analysis, and the formation mechanism was discussion based on the XRD results at various temperatures. They are different when SrCO3/BaCO3/Nb2O5 powder mixtures and the mixtures calcined at 800oC was chosen as the raw materials.
Growth and Characterizations of Relaxor-Based Pb(Mg1/3Nb2/3)O3-PbTiO3 Thin Films by Sol-Gel Method
Authors: Fan Hui Qing
Published: March 2009

Relaxor-based 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) thin films were grown epitaxially on silicon substrates by sol-gel method and PbO cover coat technique, and investigated by x-ray diffraction, auger electron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The phase development and microstrure evolution of the PMN-PT film were significantly
affected by the final annealing temperature and time. A perovskite PMN-PT film was obtained after annealing at 850oC for 1 min. Then, highly <100>-oriented and textured PMN-PT films could be achieved by using a LaNiO3 perovskite template.
Impact of Heat Treatment on the Electrical Properties of LaNiO3 Conductive Thin Films
Authors: Lu Sheng Guo , Chen Haydn
Published: March 2009

LaNiO3 (LNO) has been used as bottom electrode layer for ferroelectric and antiferroelectric thin films due to its good conduction, preferred (100) orientation, same crystalline structure as many perovskite ferroelectrics and antiferroelectrics, good adhesion and compatibility with the Pt/Ti/SiO2/Si template. In this study we have investigated the ideal optimal post - annealing conditions for LaNiO3 thin
films deposited at 450°C using a magnetron sputtering method. Heat treatment from 500 to 1200°C was performed. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and electrical measurements were carried out to characterize the morphology, structure, and macroscopic properties. Results indicated that the LNO film had the best quality when annealed at about 800°C. Above this temperature, the morphology, structure and associated properties would deteriorate.
Coating and Intergrowth of NaX Molecular Sieve Films on Porous Ceramic Paper for Membranes
Authors: Kim Ik Jin , Lee Hae Jin
Published: March 2009

NaX molecular sieve films on ceramic paper prepared by in-situ hydrothermal method were investigated. The NaX zeolite seed crystals of a uniform size of 5 µm were synthesized by hydrothermal method in a mother solution having a composition of 3.5Na2O : Al2O3 : 2.1SiO2 : 500 ~ 1000 H2O. These dip-coated NaX seed crystals on ceramic paper lead to further the thickness (20 ~ 100 µm) of NaX film on the substrate at 90°C for longer 3~7 days in autoclave. Pure zeolite films consisting of a continuous intergrown of 5~ 20 µm NaX crystal have been prepared on the substrates. The zeolite films were characterized by XRD, SEM, BET and XRF.
Preparation of Color Pearlescent Pigment Using Rare-Earth Oxide and Titanium Oxide to Coat Mica
Authors: Zhong Sheng Wen , Zhang Qian , Han De Qiang , Kuang Jing Zhong
Published: March 2009

The rare earth of Er2O3, Nd2O3, Pr6O11 as pigmentation-type coating materials was used to coat the surface of mica by wet chemical deposition method. Then the color pearl luster pigment was synthesized by heat treatment. The coating was carried out by multiple-coating technique and the influence of technique parameters on the coating was studied systematically.
Dielectric Properties of Zirconium Tin Titanate with Additives of ZnO, CuO, MnCO3 and Bi2O3
Authors: Yu H.G. , Song C.X. , Shen Z.H. , Xiong Zhao Xian
Published: March 2009

(Zr0.8Sn0.2)TiO4 ceramics with additives of ZnO, CuO, Bi2O3 and MnCO3 were prepared by the conventional mixed oxide route. They were characterized by TG/DTA, SEM, EDS and a network analyzer. Microwave properties of (Zr0.8Sn0.2)TiO4 ceramics were investigated as a function of the amount of additives. The optimal values of dielectric constant er, quality factors Q*f and temperature coefficient of resonant frequency tf reached 35, 51000 GHz and 26 ppm/°C respectively with 2.0 wt% MnCO3. Specimens with additives of ZnO, CuO and Bi2O3 had microwave properties of er = 35 ~ 39, Q*f = 9000 ~ 35000 GHz and tf = 15~40 ppm/°C.
Pretreatment of the TaSiN Substrate Surface for Copper-MOCVD
Authors: Park Hyun Ah , Lim Jong Min , Lee Chong Mu
Published: March 2009

Effects of plasma pretreatments to the TaSiN film surface on Cu nucleation were investigated. Scanning electron microscopy (SEM) was used to measure the Cu nucleation density and to observe the morphology of the Cu film. X-ray spectroscopy (XPS) and Auger depth profiling analyses were used to investigate the bonding state of atoms and the concentrations of oxygen and nitrogen at
the TaSiN film surface, respectively. Cu nucleation in Cu MOCVD is effectively enhanced by treating the underlying Ta-Si-N film surface with hydrogen plasma prior to Cu MOCVD. The Cu nucleation density in Cu MOCVD increases as the rf-power and the plasma exposure time increase in the hydrogen plasma pretreatment, but it is saturated at the rf-power of 40W and the plasma exposure time of 2min. To increase the rf-power and the plasma exposure time further would increase the plasma radiation damage for the Si substrate. Therefore, 40W and 2min are the optimal process conditions for the hydrogen pretreatment. Copper nucleation is enhanced by hydrogen plasma pretreatment because the plasma treatment removes the nitrogen and oxygen atoms from the Ta-Si-N film surface. Since
Ta-Si is a substrate more favorable for Cu nucleation than Ta-Si-N(O), Cu nucleation on the Ta-Si-N film is enhanced by hydrogen plasma pretreatment of the Ta-Si-N film surface.
Preparation and Dielectric Properties of Sm3+-Substituted SrBi8Ti7O27 Based Microwave Ceramics
Authors: Wang Yan Xiang , Fang C. , Tang Min , Qiu Hong , Xiong Zhao Xian
Published: March 2009

Sr(Bi1-xSmx)8Ti7O27 ceramics were prepared by Sm2O3-substitution for Bi2O3 through solid-state reaction route. The dielectric properties of the sintered bodies such as er, Q and tf were investigated. The ceramics were characterized by SEM, XRD, DTA and TG, which behaved high dielectric constant of 128 ~154 at the frequency of 10 GHz.
Infrared-to-Visible Upconversion Emissions in Er3+ Doped TeO2-Based Oxyhalide Glasses
Authors: Liu Yue Hui , Chen Hu , Chen Dong Dan , Zhang Qi Yi , Jiang Zhong Hong
Published: March 2009

The fluorescence and up-conversion spectral properties of Er3+-doped TeO2-ZnO and TeO2-ZnO-PbCl2 glasses suitable for developing optical fiber amplifier and laser have been fabricate and characterized. Strong green (around 527-550 nm) and red (around 661 nm) up-conversion emissions under 977 nm laser diode excitation were investigated, corresponding to 2H11/2, 4S3/2, ®
4I15/2 and 4F9/2 ® 4I15/2 transitions of Er3+ ions respectively, have beenobserved and the involved mechanisms have been explained. The dependence of up-converted fluorescence intensity versus laser power confirm that two-photons contribute to up-conversion of the green-red emissions. The novelty of this kind of optical material has been its ability in resisting devitrification, and its promising optical properties strongly encourage for their further development as the rare-earth doped optical fiber amplifiers and upconversion fiber laser systems.
Effect of PbO-B2O3 Glass Additive on the Dielectric Properties of Ba0.80Sr0.20TiO3 /Pb0.88La0.12Ti0.97O3 Composite Thick Films
Authors: Wu Rong , Du Pi Yi , Weng Wen Jian , Han Gao Rong
Published: March 2009

BST/PLT composite thick films with various content of PbO-B2O3 glass additive from 5mol% to 25mol% were successfully prepared by screen-printing the paste onto alumina substrates. XRD, SEM and impedance meter were used to analyze the phase structures, morphologies and dielectric properties of the thick films. The results showed that the BST phase has no interaction with PbO-B2O3 glass in the
composite thick films at 750 oC. Diffusion between PLT phase and PbO-B2O3 glass phase occurs and the c axis of PLT phase in thick films reduces slightly. The high infiltration between the glass phase and particles densify the composite thick films and the uniform microstructure can be obtained in the thick films with PbO-B2O3 glass additive content of 10mol%. Good temperature stability of dielectric
properties is achieved with the 25mol% content of PbO-B2O3 glass additive and the variance of the relative dielectric constant in the temperature range between 0oC and 300oC is 15%.
Properties of ZrO2/Glass-Ceramics Composite
Authors: Zhu Y.M. , Wu Xia Wan , Li Zhi Hong
Published: March 2009

In order to reduce the raw materials cost, lower the sintering temperature of 3Y-TZP optical fiber ferrules, the 3Y-TZP/ LAS glass ceramics composites were prepared and their properties were investigated in this paper. The results showed that the sintering temperatures and thermal expansion coefficients of the 3Y-TZP/LAS glass ceramics composites were lowered with the increase of glass content. The flexural strength of the composites were decreased with the increase of glass content, but
the flexural strength of the composite with 15% weight glass was higher than 400MPa. The LAS glass powder added into the composites was crystallized and b-spodumene s.s was precipitated. during sintering. The b-spodumene s.s. having lower thermal expansion coefficient and higher strength was beneficial to reduce thermal expansion coefficients and keep higher strengths of the composites .
Enhanced Sintering of TiB2 with SiC Addition Prepared by Polycarbosilane Infiltration
Authors: Lee K.J. , Kang Shin Hyuk , Kim Deug Joong
Published: March 2009

The sintering of TiB2 was limited due to its high degree of covalent bonding and low self diffusion coefficient. To solve this problem, hot pressing has been used for fabricating TiB2 ceramics, but this process was expensive and limited to the production of simple shapes. Pressureless sintering has also been studied, but its sintering temperatures is, as high as more than 2000°C, resulting in exaggerated grain growth and decrease of mechanical properties. The addition of SiC was found to be effective in improving the densification. However, a supplementary HIP process was needed to enhance the mechanical properties. In this study, the densification behavior and microstructural change of TiB2 ceramics infiltrated by the polycarbosilane of SiC precusor were investigated. The infiltrated polycarbosilane was converted to SiC during heating and densification was accelerated.
Effect of the Sintering Additives on the Microstructure and the Properties of Textured Silicon Nitride
Authors: Park Dong Soo , Kim Y.M. , Hahn Byung Dong , Park Chan
Published: March 2009

Silicon nitride samples without and with 3 wt% of the aligned b-silicon nitride whisker seeds were prepared with 8.2 wt% Er2O3 and 1.9 wt% AlN. After sintering at 2148 K for 4h, the samples exhibited densities higher than 99.5% TD. The microstructures and properties of the samples were compared with those of the samples sintered with 4.8 wt% Y2O3 and 2.2 wt% Al2O3 at 2273 K for 4h. For samples without the whiskers, the sample with 4.8 wt% Y2O3 + 2.2 wt% Al2O3 had coarser microstructures than those with with 8.2 wt% Er2O3 + 1.9 wt% AlN. However, the samples with the whisker seeds, the former sample appeared to have only slightly larger grains than the latter sample in spite of the significant difference in the sintering temperatures. For the samples without the whisker seeds, the room temperature flexural strength was higher for the sample with Er2O3 + AlN. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited higher room temperature flexural strength than that with Er2O3 + AlN although the average grain width of the former sample was larger than that of the latter sample. In case of the high temperature flexural strength at 1673 K, the flexural strengths of the samples with the whisker seeds were higher than double the strengths of the samples without the whisker seeds. For samples without the whisker seeds, the sample with Er2O3 + AlN exhibited better mechanical properties than that with Y2O3 + Al2O3. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited better mechanical properties than those with Er2O3 + AlN. The results were explained in terms of the microstructures of the samples.
Crystallization of Zirconium Nitride in Silicon Nitride Ceramics with Nitrogen Pressures and Sintering Additives
Authors: Lee S.M. , Park K.H. , Yoo Jung Whan , Kim Hyung Tae
Published: March 2009

We investigated grain boundary crystallization of gas-pressure-sintered silicon nitride with zirconia and magnesia as sintering aids. Cation compositions were mostly uniform throughout the specimen however, ZrO2 was crystallized in the surface region, while ZrN in the inside. When the specimen was heat-treated at 1 atm nitrogen atmosphere, ZrO2 in the surface region transformed to ZrN. The transformation, however, was suppressed when alumina was incorporated as an additional sintering aid. Based on these results, we propose a model describing the reaction among Si3N4, SiO2, ZrO2, ZrN and N2. Observed microstructures and measured mechanical properties were consistent with the model.
Viscosities of Oxynitride Glass and the Effects on High Temperature Behaviour of Silicon Nitride-Based Ceramics
Authors: Hampshire Stuart , Pomeroy Michael J.
Published: March 2009

M-Si-Al-O-N glasses (where M = Y or rare earth cation) are intergranular phases in silicon nitride based ceramics in which the composition and volume fraction of these oxynitride glass phases determine the properties of the material, in particular, high temperature mechanical behaviour. Investigations on oxynitride glass formation and properties have shown that nitrogen increases the glass transition and softening temperatures, viscosity, elastic modulus and hardness. By changing the cation ratios or the type of rare earth cation incorporated, properties such as viscosity can be increased further. This paper provides an overview of oxynitride glasses and outlines the effect of composition on properties such as glass transition temperature and viscosity. These effects have important implications for silicon nitride based ceramics where amorphous intergranular films control high temperature properties such as creep resistance.
Fabrication of Heat-Resistant Silicon Carbide Ceramics by Controlling Intergranular Phase
Authors: Kim Young Wook , Lee Sung Hee , Nishimura Toshiyuki , Mitomo Mamoru , Lee Je Hun , Kim Doh Yeon
Published: March 2009

The effect of glassy-phase, using AlN and Lu2O3 as sintering additives, on the microstructure and mechanical properties of liquid-phase-sintered, and subsequently annealed SiC ceramics was investigated. The microstructure was strongly influenced by the sintering additive composition, which determines the intergranular phase (IGP). The average thickness of SiC grains increased with increasing the Lu2O3 /(AlN + Lu2O3) ratio, whereas the average aspect ratio decreased with increasing the molar ratio. The homophase and heterophase boundaries of the SiC ceramics were completely crystalline in all specimens. The room temperature (RT) strength decreased with increasing the molar ratio whereas the RT toughness showed a minimum at the molar ratio of 0.6. The best results at RT were obtained when the molar ratio was 0.2. The flexural strength and fracture toughness of the ceramics were >700 MPa and ~6 MPa.m1/2 at RT. The high temperature strength was critically affected by the chemistry, especially the content of Al in the IGP. The best strength at temperatures ³ 1500oC was obtained when the molar ratio was 0.5. Flexural strengths of the ceramics at 1500oC and 1600oC were 610 ± 80 MPa and 540 ± 30 MPa, respectively. The beneficial effect of the new additive compositions (Lu2O3-AlN) on high-temperature strength of SiC ceramics was attributed to the crystallization or removal of IGP and introduction of Al into SiC, i.e., removal or reduction of Al content from the IGP, resulting in an improved refractoriness of the IGP.
Hardness Limits of SiC and Si3N4 Ceramic Materials
Authors: Balog Miroslav , Šajgalík Pavol , Lenčéš Zoltán , Hnatko Miroslav , Kečkéš Jozef
Published: March 2009

Nano- and macro-hardness of SiC and Si3N4 based ceramic materials prepared by liquid phase sintering were evaluated. The applied loads were 3.5 mN and 9.81 N, respectively. The measurements showed that the nano-hardness of both ceramics is substantially higher compared to the macro-hardness. The influence of solid solutions and grain boundary composition on the hardness of SiC-based ceramics was studied. The macro-hardness is strongly dependent on the grain boundary composition while the nano-hardness was nearly the same for all tested samples with different Re2O3-AlN additives. In the case of Si3N4 based ceramics the SiC nano-inclusions content was varied. As a source of SiC nanoinclusions and grain boundary phase modifierSiNC polymer precursor has been used. Nano- as well as micro-hardness increased with increasing SiC content. Present paper deals with the explanation of both results.
Nano Stress Measurement and Microstructural Characterization of Silicon-Based Optical Devices Using Their Native Luminescence
Authors: Leto Andrea , Pezzotti Giuseppe
Published: March 2009

Electron-stimulated luminescence (cathodoluminescence, CL, henceforth) assessments can be quantitatively used in silicon-based optical devices for obtaining information about: (i) the residual stresses piled up during manufacturing; and (ii) the micro/nanoscopic structure of the device. In the present study, a quantitative characterization is presented from a micrometer to a nanometer scale using CL bands of some optically active defects existing within the nanostructure of optical devices. In particular, some CL bands, peculiar of oxygen-related defects in silica, have shown high stress sensitivity and thus were suitable for residual stress assessments. Knowledge of residual stresses can be quantitatively established from the examination of selected spectral shift characteristics (piezo-spectroscopic method). The correlation coefficient between stress and wavelength-shift of characteristic luminescence bands was systematically evaluated by stress calibrations. The piezo-spectroscopic approach shows promises as a valuable characterization tool, suitable for routinely inspecting micromechanical features and, thus, for optimizing low-loss, highquality optical devices.
In Vitro and In Vivo Biocompatibility of Nano-Hydroxyapatite/Collagen Composites
Authors: Lin Xiao Yan , Fan Hong Song , Li Xu Dong , Tang Min , Zhang Ling Li , Tan Yan Fei , Xu Jin Rui , Zhang Xing Dong
Published: March 2009

A nano-grade hydroxyapatite/collagen composite was prepared by an in situ synthesis technique from calcium nitrate, diammoniun hydrogen phosphate, and a cowhide collagen sol at low temperature. XRD and TEM analyses of the composite indicated that crystals formed in the collagen fibril matrix were nanohydroxyapatite with low crystallinity. Biocompatibility of the composite was evaluated by in vitro cytotoxicity test and in vivo genotoxicity and sensitization test. No mutagenic activity of the composite was observed in mouse micronucleus tests. No evidence of dermal sensitization of the composite was found in guinea pig maximization tests. The results from a filter diffusion test indicated that the composite did not induce a cytotoxic behavior. All these results suggest that the composite has excellent biocompatibility.
Surface Modification for Controlling the Blood-Materials Interface
Authors: Huang Nan , Yang Ping , Leng Yong Xiang , Wang Jin , Chen Jun Ying , Sun H. , Wan Guo Jiang , Zhao An Sha , Ding Pei Dao
Published: March 2009

In the present paper, the scientific basis, technique approaches, the present status and the development trends of surface modification for blood contacting materials are discussed briefly. The work in authors’ Lab. is also presented.
Platelet Adhesion Study and Characteristic of Hydrogenated Carbon Films Synthesized by PIII-D
Authors: Wen Feng , Huang Nan , Sun H. , Yang Ping , Wang Jin
Published: March 2009

Amorphous hydrogenated carbon (a-C:H) thin films were deposited on silicon wafers and Ti6Al4V substrate using plasma ion immersion implantation and deposition (PIII-D) at room temperature (R.T.). The composition and structure of a-C:H films were employed by X-ray photoelectron spectra (XPS) and Raman spectra. Nano-indenter tests measured the hardness of the films. In addition, wettability and bloodcompatibility were investigated. In this paper, the effects of hydrogen content on structure, mechanical properties, surface wettability and haemocompatibility were discussed.
Hemocompatibility of PET (Polyethylene Terephthalate) Films Grafted PEG (Polyethylene Glycol) by Plasma Surface Modification
Authors: Pan Chang Jiang , Wang Jin , Sun H. , Huang Nan
Published: March 2009

In this paper, polyethylene glycol (PEG) of various different molecular weights was grafted onto PET films using plasma surface grafting modification. The surface structure of PEG-grafted PET films was analyzed by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS), suggesting that the surface structure and composition of PET films changes due to the presence of PEG. Blood compatibility was characterized by in vitro platelet adhesion experiments and coagulation factors. The tests of platelet adhesion and coagulation factors in vitro suggest that PEG grafted onto polymer surfaces can improve the blood compatibility of PET films remarkably. The modified PET films were pre-coated with albumin and fibrinogen respectively; platelet adhesion tests in vitro then indicated that samples pre-coated with albumin have better blood compatibility than with fibrinogen, resulting in the conclusion that the albumin can improve blood compatibility. The contact angle of PEG-grafted films was measured by the sessile drop method and the surface free energy and interface free energy were induced. It is indicated that the PEG-grafted PET films have the characteristic of preferentially adsorbing albumin.
A Dissolvable Intralumental Stent for Sutureless Vascular Anastomasis
Authors: Wang Xiao Hong , Liang X.D. , Xiong Zhuo , Yan Yong Nan , Zhang Renji , Lin Feng , Wu Ren Dong , Lu Qing Ping , Fang Ying Wu
Published: March 2009

A soluble intralumenal stent for vascular anastomosis was prepared from glucose,
Dextran-40 and heparin. The solubility of the stent was tested in vitro and in vivo.
Animal tests were carried out with femoral arteries of rabbits. In comparison with the
literature reported surgar and poly(ethylene glycol, PEG) stents, shorter dissolving time and higher patency (or survival) rate were obtained. Cell culture experiments suggested that the heparin containing glucose and Dextran-40 stent (H-sugar) had no irritation and toxicity to the endothelia cells. No thrombosis was observed from the in vivo tests in 2 months after the anastomosis. Such a heparin containing sugar stent is a promising candidate for fast sutureless anastomosis of vessels in non-trauma surgery.
Investigation on Mechanical Compatibility Matching for Biomedical Titanium Alloys
Authors: Yu Zhen Tao , Zhou Lian , Luo Lijuan , Fan Maohong , Fu Yanyan
Published: March 2009

The effects of alloying elements such as Mo, Sn, Zr, Nb, deforming-rate, solid solution and aging treatment on mechanical property and microstructure of near βtype biomedical Ti alloys based on Ti-Nb-Zr system were studied. The Influential factors and their solution were discussed to keep matching of strength, elastic modulus, plasticity and toughness. Ti-Zr-Mo-Nb and Ti-Zr-Sn-Mo-Nb alloy systems possess excellent biocompatibility, lower elastic modulus, higher strength, finer plasticity and fracture toughness matching by means of solid solution and ageing treatment which are much more suitable for surgical implant and orthopedic materials.
A Study on the Optimum Condition Selection of Rotary Dressing System of Ultra-Precision Centerless Grinding Machine for Ferrule
Authors: Lee Eun Sang , Chun Y.-J. , Kim Nam Kyung
Published: March 2009

The optimum condition selection of rotary dressing operations using Hall and AE sensor is presented. The acquired current signals from a hall sensor were studied as one of the method to obtain the optimum condition of dressing and the correlations between dressing condition and AE signals were also evaluated with the root mean square (RMS). Dressing operation was performed to investigate the effects of depth of cut, rotating speed and coolant. In order to verify the optimum condition of dressing, AE and hall sensor signals were compared in RMS with the surface micrograph of grinding wheel. This verification experiment demonstrates the effective dressing condition selection for centerless grinding.
A New Coolant Supply Method Using a Coolant Flow Guided Flexible Sheet Attracted to a Wheel Surface
Authors: Suzuki Kiyoshi , Ninomiya Shinichi , Iwai Manabu , Shishido Yoshiaki , Uematsu Tetsutaro
Published: March 2009

To improve the characteristic of the floating nozzle method, a new coolant supply method using a coolant flow guided flexible sheet was developed. In this method, all the coolant supplied from the nozzle outlet can surely be directed immediately to the grinding point, because the coolant flow guided flexible sheet made of a thin sheet material is attracted to the wheel surface automatically, and confines the coolant between the wheel surface and the sheet. Therefore, the coolant can be completely prevented from deviating away from the grinding point. In fact, when the coolant flow rate of 4 l/min was supplied from the upper part of the wheel by using this method, the amount of coolant that reached the grinding point was 18 times higher than the case of only the floating nozzle method. It was clarified that this method had the effect to improve the grinding performance. Furthermore, this new method has a possibility of the wide application such as in profile grinding and cam grinding.
Electrochemical Magnetic Abrasive Compound Finishing
Authors: Fang Jian Cheng , Xu Wen Ji , Zhao Zhi Yu , Li H.Y.
Published: March 2009

In order to find a solution to the problem of inefficiency in magnetic abrasive finishing
(MAF), electrochemical finishing (ECF) has been introduced to realize compound finishing. A new idea of integrating a magnetic pole with an electrode pole has been proposed as electrochemical magnetic abrasive finishing (ECMAF). At the same time, the occurrence of broken and dropped magnetic abrasives (MAs) has been discussed from the point of view of probability. Research on stock removal and surface roughness shows that the passive film has been removed continuously
with a new substrate material emerging during the process of machining, which accelerates the process of electrochemistry to realize the surface finishing. The finishing efficiency and surface quality have been improved by the combination of MAF with the electrochemistry process, and the various cutting behaviors of MA in ECMAF.
Mechanics of the Micro Cutting by Abrasive Particle at Vibroabrasive Processing
Authors: Babichev Anatoly P.
Published: March 2009

The results of the research of the interaction of the abrasive granule with processed
surface at vibroabrasive processing are presented. The mechanism of the micro cutting process is described on the base of the analysis of the nature of single traces of the processing, dynamic parameters of the process, geometric parameters of abrasive grains and granules.
Effects of Particles Blend Ratio on Surface Quality in Surface Polishing Using Magnetic Polishing Liquid (MPL)
Authors: Wu Yong Bo , Shimada Kunio , Wong Y.C. , Kato M.
Published: March 2009

This paper describes an experimental investigation of the effects of the particle blend ratio on surface quality in surface polishing using magnetic polishing liquid (MPL). MPL is produced by mixing sub-micrometer- or micrometer-size abrasive particles into a Magnetic Compound Fluid (MCF), a functional fluid composed of MF(Magnetic Fluid) and MRF (Magneto-rheological Fluid), that reacts with magnetic fields. As a step toward establishing the new surface finishing technology
using MPL, it is essential to clarify the effects of the blend ratio of particles to solvent in MPL. For this purpose, first five kinds of kerosene-based MPLs with different blend ratios of particles were prepared, then polishing operations involving stainless steel workpieces were carried out on an experimental rig developed in-house. During the experiments, steady state magnetic fields with different strengths were applied while the contact force between the workpiece and the polishing pad was kept constant. The experimental results showed that the blend ratio of particles affects the work-surface quality significantly. Following SEM and optical microscopy observations of the polished work-surfaces, an appropriate blend ratio, under which the surface roughness improved from the original value of Ra100nm to a final one of Ra24nm after polishing for 30min, was recommended.
Application of Nanometer-Scale Processing Technique in High-Density Recording
Authors: Wang M. , Miyake S.
Published: March 2009

To realize ultrahigh density recording in high precision using polycarbonate as a recording media, the nanometer-scale mechanical processing properties of polycarbonate and fluorocarbon plasma-treated polycarbonate were investigated using atomic force microscopy (AFM). The surface free energy of the polycarbonate specimen can be reduced by fluorocarbon plasma-treatment, resulting in processing force being reduced. Thus, nanometer-scale precise processing of polycarbonate can be realized. Lines and spaces with intervals minimized to 60 nm were performed on the fluorocarbon plasma-treated polycarbonate. Viscoelastic properties of the fluorinated polycarbonate were evaluated using AFM in force modulation mode. Fluorocarbon plasma treatment can reduce friction force of a polycarbonate sample and improve its wear resistance. Therefore, the friction durability corresponding to the reliability of data reproduction was markedly improved.
Study on Key Technologies of DNC System Oriented Networked Manufacturing
Authors: Wang Min Jie , Cai Y.J. , Yan W.G.
Published: March 2009

As one of major methods to meet information integration of numerical control machines in workshop, DNC (Direct Numerical Control or Distributed Numerical Control) oriented networked manufacturing (Web-DNC system) differs dramatically from conventional ones by having: (1) concurrently supporting networked manufacturing; (2) sharing the numerical control machines via
network; (3) optimizing the configuration and reorganization of numerical control resources. This paper deals with the key technologies of Web-DNC system, including: the implementing architecture model with four layers (user layer, service layer, agent layer and facility layer) and the topology architecture. The BL2000 SCM is selected as a COM server to meet the required capabilities of DNC controller. Compared with the communication architecture with fieldbus, a simpler function model of DNC communication technology based on Ethernet technology is presented. A Web-DNC system prototype is developed and proved to be effective in information integration of numerical control machines in injecton workshop.
Data Mining for Fault Diagnosis and Machine Learning for Rotating Machinery
Authors: Zhao Gang , Jiang Dong Xiang , Li Kai , Diao Jin Hui
Published: March 2009

Data mining is used not only for database analyses, but also for machine learning. The data mining technique described in this paper was used for steam turbine fault diagnostics based on continuous data measurements. The classification rules are based on standardized vibration frequency data for steam turbines and field experts’ analyses of turbine vibration problems. The expert knowledge enables the steam turbine fault diagnosis system to be more powerful and accurate. The system can identify twenty types of standard steam turbine faults. The system was developed using 2000 simulated data sets. The data mining methods were then used to identify 20 explicit rules for the turbine faults. The method was also used with actual power plant data to successfully diagnose real faults. The results indicate that data mining can be effectively applied to diagnosis of rotating machinery by giving useful rules to interpret the data.
Identification of Discontinuities in Composite Rods and Beams Based on Lamb Wave Propagation
Authors: Grabowska Joanna , Krawczuk Marek
Published: March 2009

The article presents a method of damage identification in composite rods and beams
based on the analysis of changes in Lamb wave propagation. For modelling of the problem the spectral element method is used. Spectral elements of rod and beam suitable for modelling the composites are employed. In the presented paper the following discontinuities are analysed: the fatigue open and not propagating crack, changes in the cross-section area, material discontinuities, various fibres volume and angle. The influence of discontinuities on the Lamb wave propagation processes is analysed.
Defocusing Detection of Geometric Sizes in Micro-Machining
Authors: Qu Xing Hua , Zhao X.H. , Ye S.H.
Published: March 2009

Porous silicon with pore size in the range of a few nanometers can be used as multifunctional material in different MEMS applications. Via an electrochemical etching method, porous silicon is fabricated on the silicon substrate and removed as a sacrificial layer by using KOH solution to form a micro structure. This technique is typical in micro fabrication. Three-dimensional size is the basic geometric feature to describe microstructure surface characteristics. It is important to investigate measurement methods for it. UBM Microfocus Measurement System based on defocusing error detection is adopted to measure eroded depth of silicon cup. The measured data in the experiments are analyzed. The influence of etching time, current density and silicon type on etching depth can be acquired. Effective reference data can be provided for studying micro fabrication methods.