bluuebunny/crossref_metadata_2025 huggingface dataset:
Excessive Iron Source on the Structural and Electrochemical Properties of LiFePO4/C Composite
Authors: Lin Yan , Wu Jian Bo , Yu Yong Biao
Published: August 2010

LiFePO4 is one of the most promising cathode materials for lithium ion battery, especially those used in electrical vehicles and hybrid electrical vehicles. However, its very poor rate performance caused by its low electronic and ionic conductivity limits the wide utilization in high power lithium ion battery. Iron phosphides, such as FeP and Fe2P, were reported to have positive effect on the improvement of the rate performance. In order to improve the electrochemical properties, LiFe1+xPO4/C (x = 0-0.1) composite with various contents of iron phosphides was synthesized by adding different amount of iron source during a sol-gel process. The amount of iron phosphides increased with the increase of iron source. Electrochemical performance showed that the samples with 1% iron source in excess had better rate performance than the LiFePO4/C sample synthesized with stoichiometric iron source. However, the overall samples with excessive iron source showed relatively low specific discharge capacity. Hence, some balance between the rate capability and discharge capacity should be found and the amount of the in-situ formed iron phosphides should be optimized.
Influence of CoO Phase on Structural, Magnetic and Electrical Properties of La0.7Ca0.3MnO3 and La0.7Sr0.3MnO3
Authors: Bian Jin Long , Seo Yong Jun , Kim Geun Woo , Sung Chang Hoon , Kumar Shalendra , Lee Chan Gyu , Koo Bon Heun
Published: August 2010

The composites of (1-x)La0.7Ca0.3MnO3/xCoO and (1-x)La0.7Sr0.3MnO3/xCoO (x =0 ~ 0.09) were fabricated by conventional solid state reaction method, and their electrical transport and magnetoresistance (MR%) properties were investigated by physical property measurement system (PPMS). The result of x-ray diffraction (XRD) and scanning electronic microscopy (SEM) indicated that no new phase appeared in the composites except manganites matrix and CoO phases. CoO is mainly distributed at the grain boundaries and surfaces of the matrix. The resistivity LCMO and LSMO based composites were measured in the range 90-320K and 90-400K, respectively. The applied magnetic field is 0T and 0.5T. The observed variation of MR with varying Ca and Sr concentration has been qualitatively investigated.
Optical Characterization of Eu3+ and Tb3+ Ions Doped Zinc Lithium Borotellurite Glasses
Authors: Sudhakar Reddy B. , Vemasevana Raju K. , Sailaja S. , Nageswara Raju C. , Sreekantha Reddy D.
Published: August 2010

This paper reports on the development and spectral results of Eu3+ and Tb3+ ions doped zinc lithium boro tellurite glasses in the following composition:
20TeO2 - (60-x) B2O3 -10 ZnO-10Li2O-x Eu2O3
20TeO2 - (60-x) B2O3 -10 ZnO-10Li2O-x Tb4O7
(where x= 0.125, 0.25, 0.375, 0.5 , 0.625 mol %)
The measured emission spectrum of Eu3+ glass have revealed five transitions (5D0→7F0, 7F1, 7F2, 7F3 & 7F4) at 578 nm, 592 nm, 612 nm, 643 nm, 701 nm respectively with λexci=392 nm (7F0→5L6) .In the case of Tb3+ glasses four emission transitions such as (5D4→ 7F6, 7F5,7 F4 & 7F3) that are located at 488 nm, 543 nm, 583 nm and 614nm respectively have been measured with λexci=376 nm. For all these emission bands decay curves have been plotted to evaluate their life times.
Manufacture Technology of Novel Reinforcing Composite Geotextile Made of Recycled Nonwoven Selvages
Authors: Lin Jia Horng , Lin Chin Mei , Kuo Chih Yuen , Lin Ching Wen , Hsieh Chien Teng , Lou Ching Wen
Published: August 2010

The nonwoven waste coming from textile industry takes up 5% of the total waste amount, so to recycle and to regenerate the waste is the prior obligation of the factory to reduce the waste. Nonwoven selvages waste can be buried or burnt but these two methods result in environmental pollution. This research proposes to reuse these waste nonwoven selvages effectively, and is designed as follows. Each piece of thermal-bonding material comprised a sandwich structure, with two layers of 7.0d PET matrices enclosing a layer of PP nonwoven selvage and nylon geogrid. After needle-punching and thermal-pressing, it forms a laminate structure of PET nonwoven/ PP selvage/ PET nonwoven in that it decreases the impact by the environmental pollution and protects the environment ultimately. In addition, thermal-bonding reinforces the mechanical properties of the composite fabric structure. The results of the experiment suggest the optimum manufacture parameters (selvage content: 10 %; thermal-bonding temperature: 220°C; needle-punching density: 400 needles/ cm2). The composite fabric undergoes the burst strength test and permeable coefficient measurement, evaluating its applications in geotextile filed.
Nanoeffects of Nanocomposites on the Petroleum Recovery and Solar Energy Efficiency
Authors: Ke Yang Chuan , Yang Li , Wang Yu Guo , Li Lin , Hu Yi , Wang Ai Jun
Published: August 2010

Several polymer inorganic nanocomposites were specially designed for protecting oil formation, enhancing oil recovery in the low permeable strata and solar cell efficicency. The inorganic phase with different load was introduced to the polymer matrix through either the intercalation process of the layered silicates or core-shell particle affinity.Several novel nanoeffects were discovered in such polymers as polyacrylamide, poly(ethylene terephthalate),starch, polynucleic aromatic resins–montmorrilonite or SiO2 nanocomposites. In the nanocomposites, the nano size was 10-70nm, the nanoeffects of particle encapsulation, dispersion, molecular weight growth, barrier, and specially solar absorption and solar power transformation efficiency,etc.were presented and reviewed. The tunable nanoeffects of the nanocomposites and some very obvious practical efficicnecy to traditional and new enenergy were first reported.
Photoelectrocatalytic Degradation of Isopropyl Alcohol by TiO2/Ti Thin-Film Electrode
Authors: Cheng Kai Yuan , Yao Kuo Shan , Lo Hsueh Hsia , Chang Chen Yu , Chen Po Hsiang
Published: August 2010

Advanced oxidation processes (AOPs) are potential technologies for the treatment of wastewaters containing non-easily removable organic compounds. Isopropyl alcohol (IPA) is one of the groups with high toxicity and low biodegradability and is always interested by researchers. In this study, Chemical Vapor Deposition (CVD) was used to immobilize TiO2 photocatalyst on the titanium substrate plate and extra applied electric potential on the working electrode (anode) combined with a 365 nm UV lamp for irradiating the IPA wastewater to conduct a photoelectrocatalytic reaction. The experimental results showed, during the photoelectrocatalytic reaction, the extra applied electric potential could inhibit the recombination of the electron-hole pair and raise the overall removal efficiency. However, when the potential was more than 0.5 V, it would reduce the photoelectrocatalytic effect because of the recombination of electrons and holes. Moreover, adding different electrolyte solutions enhanced the different degree of effects of IPA removal. Among the electrolyte solutions added, sodium sulfate improved the photoelectrocatalytic effect most significantly.
Preparation and Properties of P-Type Transparent Conductive NiO Films
Authors: Chen Sheng Chi , Kuo T.Y. , Lin Y.C. , Chang C.L.
Published: August 2010

The NiO-Cu composite films with various Cu contents of 0 – 18.17 at.% are deposited on glass substrate. An ultra high electrical resistivity (ρ) is obtained and cannot be detected by four point probe measurement when the Cu contents in the films are lower than 6.97 at.%. The ρ value is reduced significantly to 35.8 Ω-cm as Cu content is increased to 9.18 at.%, and it further decreases to 0.02 Ω-cm when the Cu content further increases to 18.17 at.%. The Hall measurement for all Cu-doped NiO films show p-type conduction. In addition, the transmittance of NiO films also decreases continuously from 96 % to 43 % as Cu content increases from 0 to 18.17 at.%. The XRD patterns of Cu-doped NiO films only appear NiO peaks and the crystallinity of NiO films becomes worse as Cu content is added to above 6.97 at.%. Large amount of lattice sites of Ni2+ ions in NiO crystalline are replaced by the Cu+ ions that leads to p-type conduction and result in the degradation of crystallinity for NiO-Cu composite films having higher Cu content.
Room Temperature Growth of Cerium-Iron Oxide Nanorods
Authors: Arul N. Sabari , Mangalaraj D. , Ponpandian N. , Chen Pao Chi , Yi Junsin
Published: August 2010

Cerium-iron oxide composite nanorods were synthesized by a surfactant free precipitation method. The synthesized products were characterized by XRD, FESEM, BET and TEM. Increase in the mole concentration causes the morphology of the cerium oxide to change from nanorods into nanocubes. X-ray diffraction pattern shows a diffraction peak at 28.5° corresponding to (111) reflection plane normal to c axis of a cubic fluorite structure of CeO2 and also hexagonal phase of Fe2O3 and orthorhombic phase of FeO (OH). EDAX analysis on individual nanorod conform the presences of Iron, which supports the XRD spectra. From transmission electron microscopy (TEM), the length and width of the nanorods were estimated in the range of ~100-350 nm and ~20-40 nm respectively. The Brunauer Emmett Teller (BET) analysis showed the increase in surface area for the obtained nanorods with respect to the increase in Fe concentration which in turn enhanced the formation and growth of nanorods.
Co3Pt Nanocomposite Films for Perpendicular Magnetic Recording Media
Authors: Shen Chih Long , Kuo Po Cheng , Chen Sheng Chi , Chen C.D. , Hsu S.L. , Lin G.P. , Huang K.T.
Published: August 2010

The Co3Pt magnetic layer with thickness of 7~28 nm was deposited onto the Pt underlayer. The as-deposited Co3Pt/Pt double-layered films with or without a 5 nm Pt capped layer were annealed at temperatures between 275 and 375 °C in vacuum of 1 mTorr. The influences of process parameters on perpendicular magnetic properties of Co3Pt thin films were investigated. The Co3Pt film with perpendicular coercivity (Hc⊥) value of 3620 Oe and the perpendicular squareness (S⊥) of 0.7 could be achieved from the Co3Pt(18 nm)/Pt(100 nm) double-layered films by annealing at 300°C. Further added Tb30Co70 film on the Co3Pt/Pt double-layered film could greatly enhance the perpendicular magnetic properties of the film. The Hc⊥ and S⊥ of the Tb30Co70/Co3Pt/Pt film were as high as 6560 Oe and 0.88, respectively, which has significant potential to be applied in perpendicular magnetic recording media.
Assessing the Effects of Natural Variations in Microstructure for the Biomimetic Modeling of Cuttlebone
Authors: Cadman Joseph , Chen Yu Hang , Zhou Shi Wei , Li Qing
Published: August 2010

Cuttlebone is a natural material possessing a unique microstructure providing a high compressive strength to weight ratio. It is potentially desirable to use cuttlebone directly in engineering applications or to design new biomimetic materials based on the microstructural features of cuttlebone. A finite element based homogenization method can be used for characterizing the mechanical properties of such a biomaterial and for the design of biomimetic materials. However, this method assumes a periodicity of microstructure, which does not reflect the variation present in natural or fabricated materials. The method can be extended to investigate the effect of natural variation and manufacturing tolerance by enlarging the base cell domain to include a number of representative volume elements (RVEs) and applying a random displacement vector to the nodes at the internal intersections of the RVEs. As the boundary of the base cell domain is not modified, the homogenization method can still be employed to calculate the bulk mechanical properties. It is found that the number of RVEs in the base cell has an impact on the decrease in mean stiffness tensor components, while the length of the introduced variation seems to influence both the mean and the standard deviation of stiffness tensor components.
Effects of Material on the Deployment of Coronary Stents
Authors: Tammareddi Sriram , Li Qing
Published: August 2010

Coronary stents have been more and more widely used in clinic over the past decade. There have been a large number of stents made of different biocompatible materials available commercially in the market. It is however unclear which is more suitable to specific patients. This raises a major concern whether the choice of stents could be assessed before a delivery surgery. This paper aims to provide a computational approach for evaluating the effect of stent materials on biomechanical outcomes of the deployments of stents in different patient. It will review the typical biomaterials being used for coronary stents, seeking to qualitatively assess them for use as coronary stents. Non-linear explicit finite element (FE) procedure is carried out using the Palmaz-Schatz stent geometry to quantitatively predict the effect of mechanical properties of these biomaterials on stent and coronary artery behavior during stent deployment. A quantitative comparison is made for exploring the effect of different materials on the deployment of stents. The study is considered significant in understanding the role how stent materials affect biomechanical responses to the coronary stenting. It provides a new methodology to promote a patient-specific assessment before surgery.
Morphological Variations of Hydroxyapatite Nanostructures by Different Synthesis Methods
Authors: Nathanael A. Joseph , Mangalaraj D. , Yi Junsin
Published: August 2010

Multiform morphologies of hydroxyapatite nanostructures were synthesized by different methods. Some novel methods were adopted for preparing different morphologies. The morphological analysis confirms that the preparation method greatly influences the morphological characterization. The morphological analysis further confirmed by the TEM analysis. The nanostructure clearly depicts the growth stages of the HAp. The interplanar distances measured in segments (fringes) of the HRTEM micrograph were ~0.35 nm, corresponding to the interplanar spacing of the [002] plane of the hexagonal hydroxyapatite. X-ray Diffraction (XRD) measurements indicate the formation of crystalline hexagonal hydroxyapatite. The morphological dependent properties were analyzed in detail.
The Effect and Characteristics on Chitosan Nanoparticles with Different Concentration of TPP
Authors: Chou Chih Wei , Harn Horng Jyh , Hseu You Cheng , Shih Yang Chia , Wu Te Hsing
Published: August 2010

Chitosan nanoparticles (CS NPs) was prepared by mixed with TPP for drug release carrier in this study. Generally, Chitosan is a good and non-toxic biodegradable polysaccharide polymer with low immunogenicity. Tripolyphosphate (TPP) is a polyanion, and can interact with cationic chitosan by electrostatic forces. So Chitosan/TPP nanocomposites were synthesized Berberine, a naturally occurring isoquinoline alkaloid, was shown to have anti-inflammatory and anti-tumour properties in vitro systems. And we have used the transmission electron micro-graphs (TEM) and Dynamic light scattering (DLS) to gain the CS nanoparticles’ size. The action of tripolyphosphoric groups of TPP crosslinked with ammonium groups on chitosan in the nanoparticles and it was identified by FTIR. We also obtained the poison property of berberine mantled by CS NPs to human breast cancer cell.
Effect of Additives on the Performance of PU/SiO2 Hybrid Membrane
Authors: Nie Xin Xin , Zhao Zi Nian , Cheng Xiao Yan
Published: August 2010

By mixing PEG or LiCl respectively into the casting solution, the polyurethane (PU)/SiO2 hybrid membranes were prepared by means of immerged phase inversion process. The method of NMR relaxation time T1 value was used to determine effect of the segmental movement of PU macromolecule in the casting solution on the microporous structure of membrane. The membrane section photos of SEM and properties of the PU hybrid membranes were investigated respectively. The results showed that blending SiO2, and with LiCl or PEG into the PU solution system, the T1 value synchronistically decreased. That was relaxed of PU chain winding and ease to move. The additives of PEG could influence the casting solution of PU, it enhanced the distribution of SiO2 in the casting solution, and formed fine interfacial micropores, meanwhile the retention of the membranes were increased to certain degree whereas the pure water flux could kept at a higher level. Similarly, adding some quantity of LiCl could obtain the membrane with higher retention under the condition of slightly loss of pure water flux. Even thought that there were equivalent quantities of finger pores in section of membrane, mixing PEG or LiCl in the casting solution, the SEM section photos indicated that there were more micropores in the wall of pore.
The Development of Gelatin/Chitosan Hybrid Scaffold for Mouse Embryonic Stem Cell Line ATDC5
Authors: Li Yuan , Matsuda Naoki , Bao Xu Xu , Teramoto Akira , Abe Koji
Published: August 2010

Functional scaffolds fabricated from biopolymers are of great importance for tissue engineering. In this paper, by mimicking the combination of two major components in Extracellular Matrix – collagen and polysaccharide respectively, we fabricated gelatin and chitosan hybrid sponge for cartilage tissue engineering. Extending previous results of gelatin/chitosan film showed that all the hybrid coating film (chitosan: gelatin= 4:1; 1:1; 1:4) can support the adhesion of ATDC5 that comparable to Tissue Culture Dish (TCD). More importantly, stem cell line ATDC5 on coating dish of chitosan: gelatin=1:4 showed enhanced differentiation rate than that on other films and TCD. For three dimensional scaffolds, we fabricated hybrid sponge scaffold of chitosan: gelatin=4:1, 2:1, 1:1, 1:2, 1:4 respectively. Morphological characterizations of the sponges showed that this kind of gelatin/chitosan hybrid scaffold is promising for application in cartilage tissue engineering.
Adhesion Strength of BNT Films Hydrothermally Deposited on Titanium Substrates
Authors: Xu Fang Chao , Kusukawa Kazuhiro
Published: August 2010

Lead-free piezoelectric (Bi1/2Na1/2)TiO3 (BNT) films were deposited on 1 mm thick pure titanium(Ti) substrates by a hydrothermal method. Tensile tests were performed to quantitatively assess the adhesion strength between BNT films and Ti substrates. Ti substrates were pretreated by chemical polish and mechanical polish respectively prior to BNT film deposition. In the tensile test, the behavior of BNT film exfoliation was investigated by the replica method. The critical Ti substrate strain inducing BNT film exfoliation was determined by the aid of finite element analysis (FEM). In this study, the results revealed that BNT film exfoliations were caused by the strain of Ti substrate, and the mechanical polish pretreatment improved the adhesion of BNT film to Ti substrate.
Effects of Hot Isostatic Pressing on the Microstructure of the Ni-Base Super-Alloy
Authors: Choi Choul Jun , Choi Hyun Yong , Yang Dong Jo , Kim Jae Yeol
Published: August 2010

Applied gas turbine blade material(Ni base Super-alloy) for aircraft as principal parts material of existing electricity generating gas turbine blade. Studied microstructure change after do heat treatment, Hot Isostatic Press(HIP) processing to nickel-based super-alloy. Emphasize in properties of matter refreshing effect confirmation by HIP processing, microstructure observed by scanning electron microscope.
HIP processing effect caused positive effect in high temperature Creep and low cycle fatigue failure by microscopic air hole exclusion. Sheep of Eutectic region decreased solid solution being done B, and also precipitated size of cuboidal shape great. Heat treatment effect was seen modification by M23C6 carbide creation that Script MC carbide is microscopic and does Discrete through solution treatment in high temperature state. Precipitation that grow after HIP processing over solution processing and aging processing in heat treatment process solid solution after is done again precipitate being done size decrescent.
Effects of Mechanical Alloying on the Mechanical and Tribological Properties of Al-Cu-Mg Matrix Composites Reinforced by Sub-Micron Silicon Carbide Particles
Authors: Deng Xiao Yan , Xu Jin Cheng , Hua Wei , Tian Liang Liang , Ai Li Jun , Zhang Jie
Published: August 2010

Al-Cu-Mg alloy and its matrix composites reinforced with different volume fractions of sub-micron silicon carbide particles have been produced in powder metallurgy route. The effects of silicon carbon particles and mechanical alloying (MA) technology on the mechanical and tribological properties were investigated. The results show that the composites have better mechanical and tribological properties than the matrix alloy, and the 9vol%SiCp/Al-Cu-Mg composite has the best performances. Mechanical alloying (MA) technology further improves the hardness and tensile strength, hardly influences the wear rate of the 9vol%SiCp/Al-Cu-Mg composite but somewhat affects its friction coefficient.
Coupling of Continuum Damage Mechanics with De-Cohesive Element for Delamination Analysis in Laminated Composites
Authors: Hosseini-Toudeshky Hossein , Mohammadi Bijan
Published: August 2010

To predict the progressive damages including the large delamination growth in composite laminates, a new interface de-cohesive constitutive law is developed which is compatible with 3D continuum damage mechanics (CDM). To avoid the difficulties of 3D mesh generation and 3D interface modeling between the layers, the interface element is implemented in the Reddy’s full layer-wise plate theory. An angle-ply laminate is analyzed to evaluate the developed CDM+Interface procedure in edge delamination initiation and evolution at final stage of CDM damage progress.
Implementation of the Method of Fundamental Solutions and Homotopy Analysis Method for Solving a Torsion Problem of a Rod Made of Functionally Graded Material
Authors: Uscilowska Anita
Published: August 2010

The purpose of this paper is the application of Method of Fundamental Solutions (MFS) to the torsion problem of hollow rods made with functionally graded materials. This method belongs to so-called meshless methods. The proposal of the paper is to solve the problem by numerical procedure, which is proper combinations of the Method of Fundamental Solutions, the approximation by Radial Basis Functions (RBF) and Homotopy Analysis Method.
The numerical experiment has been performed for the bar with circular cross-section.
Interacting Crazing Patterns Near the Tip in the Damage Zone of a Crack
Authors: Seddiki H. , Chabaat M.
Published: August 2010

The present paper investigates interactions between a main crack and a surrounding layer of crazing patterns. Analysis of the stress field distribution as well as the energy induced during these interactions is based on the resolution of some equations along with appropriate boundary conditions and the use of a numerical approach. The effect of amplification and shielding on the resulting stress field is shown through a study of mode I Stress Intensity Factor (SIF). Besides, to quantify the effects of this damage on the main crack, it is shown that the Energy Release Rate (ERR) is defined as being a superposition of the energy released due to the linear propagation of the main crack as well as the one due to the translational change in the growth of the damage. It is also proven that crazes closer to the main crack dominate the resulting interaction effect and reflect an anti-shielding of the damage while a reduction constitutes a material toughness.
Optimal Design of the Aluminum Electrical Railcar under Uncertainty of Material Property
Authors: Cho Tae Min , Lee Byung Chai , Kwon Tae Soo
Published: August 2010

In this study, optimal design of the aluminum electrical railcar under uncertainty of material property is performed. The main structure of the aluminum electrical railcar is composed of aluminum extruded panel. The yield strength and thickness of the aluminum extruded panel are treated as random variables. The loading conditions are based on the standard specification. Stress and resonant frequency are the design constraints and obtained through finite element analysis. The results of reliability-based design optimization considering the uncertainty of material property are compared to those of deterministic optimization.
Buckling Analysis of Micro- and Nano-Rods/Tubes Based on Nonlocal Timoshenko Beam Theory Using Chebyshev Polynomials
Authors: Ghannadpour Seyyed Amir Mahdi , Mohammadi Bijan
Published: August 2010

This paper presents the elastic buckling behavior of nonlocal micro- and nano- Timoshenko rods/tubes based on Eringen’s nonlocal elasticity theory. The critical buckling loads are obtained using the theorem of minimum total potential energy and Chebyshev polynomial functions. The present method, which uses Rayleigh–Ritz technique in this paper, provides an efficient and extremely accurate buckling solution. Numerical results for a variety of some micro- and nano-rods/tubes with various boundary conditions are given and compared with the available results wherever possible. Through the comparison of the results and the appropriate discussion, the knowledge of the level of capability of the developed method is promoted. The small scale effects on the buckling loads of rods/tubes are determined and discussed.
Effect of Gold Addition on Electrical and Optical Properties of NiO Films by Rf Sputtering
Authors: Chen Sheng Chi , Lin Y.C. , Kuo T.Y. , Chang C.L.
Published: August 2010

The NiO-Au composite films with Au contents of 0 to 33.7 at.% are deposited on glass substrates. The high electrical resistivity (ρ) of Au-doped NiO films with Au contents below 1.0 at.% is difficlut to measure by four point probe. The ρ value could be reduced to 30.4 Ω-cm as Au content of 1.4 at.% is added into NiO film. It is reduced significantly to 0.375 Ω-cm as Au content is increased to 13.6 at.%. Further increasing the Au content to 33.7 at.%, the ρ value of NiO film is further decreased to 4 x 10-4 Ω-cm. On the other hand, the transmittance of Au doped NiO films also decreases with increasing Au contents. The transmittance for pure NiO film is as high as 96 %. As the Au contents of 1.4, 13.6, and 33.7 % are added into NiO film, they are decreased drastically to 45 %, 20 %, and 9 % respectively. The XRD patterns of Au-doped NiO films with Au content below 9.6 at.% only appear NiO peaks and their (200) peaks shift slightly to low angle as Au content is increased. When Au content is added to above 9.6 at.%, the NiO crystalline become worse. In addition, further increasing the Au content to above 13.6 at.%, the (111) peak of Au also appears in XRD patterns. This indicating that the Au atoms instead of part of Ni atoms results in the enlargement of NiO lattice for Au-doped NiO film with lower Au contents, but large amount of Au atoms are precipitated from the NiO lattice when the content of Au in the NiO film is increased to above 13.6 at.%.
Effect of Pd Nanoparticles on Thermal Degradation Kinetics of iPP/Pd Nanocomposite
Authors: Lee Jae Young , Choi Bum Choul , Lee Ji Jung , Yang Sung Won , Lee Hong Ki
Published: August 2010

Palladium (Pd) nanoparticles were incorporated into free-standing polymer films, where isotactic polypropylene (iPP) was used, by a one-step dry process involving simultaneous vaporization, absorption and reduction schemes of palladium(II) bis(acetylacetonate), Pd(acac)2 at 180oC, used as a precursor. iPP film was exposed to the sublimed Pd(acac)2 vapor in a glass vessel with nitrogen atmosphere heated at 180oC. The exposing time was 30 min and the Pd nanoparticle contents in polymer films were estimated from ash contents in a sample of about 5 mg by pyrolysis of the films at 800 oC for 1 h in an electric furnace of the TGA apparatus under dry argon atmosphere. The sensitivity of the TGA apparatus was 0.2 mg, and thus the minimum content to be measured was 0.004 wt% of a 5 mg sample. The reduced Pd nanoparticles were observed by transmission electron microscope (TEM), and it was found that metal nanoparticles were selectively loaded into the amorphous regions between the lamellae of crystalline polymers having higher melting temperatures than the processing temperature (180 oC). In order to measure the thermal degradation rate, TGA data measured by the heating rates of 5, 10, 15 and 20 oC /min at the nitrogen atmosphere of 200 ml/min. The TGA data was introduced to the Ozawa equation and the degradation activation energy was calculated according to the degradation ratio.
Fabrication of Ag Nanoparticles Colloids by Pulsed Laser Ablation in Liquid
Authors: Xu Bing , Song Ren Guo
Published: August 2010

Ag nanoparticles colloids have been fabricated by pulsed laser ablation in various liquids. The particle size, morphology and absorption spectroscopy of the obtained nanoparticles colloids were characterized by ultraviolet to visible (UV-Vis) spectrophotometer and transmission electron microscopy (TEM), the average diameter and its distribution were analyzed by Image-ProPlus software. The results showed that the Ag nanoparticles with best characterization are those produced at the repetition rate of 10Hz and laser fluence of 4.2J/cm2 by ablating for 7.5min in the distilled water, with the least average diameter(D=14.48 nm), the narrowest distribution of particles size (=25.8 nm) and more homogeneous morphologies. The effects of experimental conditions on the silver nanoparticles colloid can be explained by fragmentation and melting induced aggregation of colloidal particles by self-absorption of laser pulses.
Large-Scale Synthesize ZnO Micro/Nano Rods Fabricated from Aqueous Solutions at Low Temperature
Authors: Yang Gang Qiang , Zou Xiao Ping , Meng Xiang Min , Teng Gong Qing , Cheng Jin , Su Yi , Lü Xue Ming , Wei Cui Liu , Sun Zhe , Feng Hong Ying , Yang Yuan
Published: August 2010

ZnO micro/nano rods were grown　on fluorine doped tin oxide (FTO) substrates by aqueous chemical growth (ACG) using Zn(NO3)2•6H2O and C6H12N4 at low temperature. For comparison, the yield of nanorods on indium-tin-oxide (ITO) substrates with same parameters was also discussed. SEM, TEM, SAED and XRD were utilized to characterize morphologies and structures of ZnO crystals. It was indicated that the temperature and the concentration of the solution significantly leads to the yields of the ZnO. Single-crystalline ZnO micro/nano rods could be synthesized via an aqueous solution route without adding alkali solution at 70°C in large area.
Lead Hydroxide Nanowires Obtained from Lead Nitrate Solution by Adding Chloride Ions
Authors: Cheng Jin , Zou Xiao Ping , Meng Xiang Min , Yang Gang Qiang , Lü Xue Ming , Wei Cui Liu , Sun Zhe , Feng Hong Ying , Yang Yuan
Published: August 2010

The synthesis of lead hydroxide nanowires by solution-phase chemical reactions of lead nitrate with alkali by adding sodium chloride was reported. The obtained lead hydroxide nanowires have a length of a few micrometers and a diameter of about several tens of nanometers. The selected-area electron diffraction reveals that these lead hydroxide nanowires are single crystalline. Controlled experiments indicate that lead hydroxide nanowires prefer to form at higher concentration of chloride ions in lead nitrate precursor solutions, such as Cl- : Pb2+ = 5:1 and 6:1.
Synthesis of Graphene Nanosheets via Thermal Exfoliation of Pretreated Graphite at Low Temperature
Authors: Meng Long Yue , Park Soo Jin
Published: August 2010

In this work, we synthesized graphene nanosheets via a soft chemistry synthetic route involving pre-exfoliation treatment, strong oxidation, and post thermal exfoliation. X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) confirmed the ordered graphite crystal structure and morphology of graphene nanosheets. N2 adsorption was used to determine the specific surface area of graphene nanosheets. As a result, pre-treatment of the graphite with HNO3/H2SO4 mixture produced the exfoliated graphite nanoplates, and the post thermal exfoliation of the graphite oxide nanosheets at low temperature led to produce a large number graphene nanosheets. The specific surface area of obtained graphene nanosheets was 333 m2/g.
Fabrication and Properties of La-Manganite/SnO2 Composites
Authors: Kim Geun Woo , Seo Yong Jun , Bian Jin Long , Lee Chan Gyu , Koo Bon Heun
Published: August 2010

Composites with compositions La0.7Ca0.3MnO3(LCMO) and La0.7Sr0.3MnO3(LSMO)/SnO2 were prepared by a standard ceramic technique. The structure and morphology of the composites have been studied by the X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The XRD and SEM results indicate that no reaction occurs between La based maganite and SnO2 grains, and that SnO2 segregates mostly at the grain boundaries of La based maganite. The variation in resistivity with temperature has been studied and shows a semiconducting behavior, furthermore the composites exhibit metallic percolation. It is interesting to note that an enhanced magnetoresisitance (MR) effect for the composites is found over a wide temperature range from low temperature to room temperature in an applied magnetic field of 0.5 Tesla. The spin-polarized tunneling and the spin-polarized tunneling may be attributed to the enhanced low-field magnetoresistance (LFMR) effect.
Temperature Independent Delamination Detection Using Data Normalization
Authors: An Yun Kyu , Lim Hyung Jin , Sohn Hoon
Published: August 2010

This paper describes a new delamination detection technique for a composite structure under varying temperature. Guided waves and impedances have the merits of being sensitive to small defects of a structure. However, they can be vulnerable to environmental and operational variations. In reality, structures are subject to various environmental and operational conditions that affect measured guided wave and impedance signals, and these ambient variations can often lead false alarms. To tackle this issue, a data normalization procedure that distinguishes structural damage from undesirable ambient variations, is developed. The overall procedures of the proposed method are (1) the temperature estimation from impedance data using data normalization, (2) the selection of guided wave signals related to the estimated temperature, and (3) damage classification based on generalized extreme value statistics. In order to validate the proposed method, experimental studies under varying temperature are investigated in a composite plate.
Characteristics of PP/PET Bicomponent Melt Blown Nonwovens as Sound Absorbing Material
Authors: Lee Bang One , Ko Jung An , Han Sang Won
Published: August 2010

Melt blowing(MB) is a process for producing fibrous webs or articles directly from polymers or resins using high-velocity air or another appropriate force to attenuate the filaments. This process is one of the newer and least developed nonwoven processes. This process is unique because it is used almost exclusively to produce microfibers rather than fibers the size of normal textile fibers. MB microfibers generally have diameters in the range of 2 to 4 ㎛, although they may be as small as 0.1 ㎛ and as large as 10 to 15 ㎛. The material acoustic property for noise absorption is principally based on the efficiency of material structures for damping sound wave reflections. In this paper, the sound absorbing material was designed with three layer composite sturcture. Sound absorbing material with fine meltblown(0.5~3 ㎛, 80%) and high modulus hollow fiber(30 ㎛, 20%) as a surface layer and bulky non-woven(15~30 ㎛) as middle layer, meltblown(3~10 ㎛) as bottom layer were manufactured. Their noise absorption were measured using the acoustic duct instrurment. The effect of the sound absorbing on the properties of PP/PET bico MB webs was investigated including the fiber diameter, weight, thickness and air permeability.
Design of Broad Band Radar Absorbing Composite Laminates
Authors: Kim Jin Bong , Kim Chun Gon
Published: August 2010

The purpose of this study is to present the optimal design technology on the broad band radar absorbing composite laminates. The design concept is based on the 2-layer Dällenbach type radar absorber, in which the composite laminates act as the lossy layers. The radar absorbing function was achieved by controlling the electromagnetic property of the composite laminates by means of adding carbon nano materials into the matrix resin of the fiber-reinforced composite laminates. The laminates were fabricated with the E-glass fabric/epoxy prepregs and cured in an autoclave. The electromagnetic properties were measured for the frequency band of 0.5 ~ 18.0 GHz using a coaxial air line and a vector network analyzer. The radar absorbers were designed to have optimal absorbing performance in 10 GHz. The optimization was conducted to get the optimal number of the plies of the laminates and filler contents of the carbon nano materials in the respective layers. The performances of the fabricated absorbers were measured to be compared with the design results. The discrepancy between the design and the measurement was discussed.
Magnetic Field Activation of Thermoresponsive Shape-Memory Polymer with Embedded Micron Sized Ni Powder
Authors: Zhang Da Wei , Liu Yan Ju , Leng Jin Song
Published: August 2010

The shape memory polymer (SMP) materials are able to change these shape in response to external stimulus such as stress, temperature, solvent, PH, magnetic, electricity or light. The above-mentioned methods are only to recover initial shape of the deformed SMP, could not give the SMP predeformation. In this paper, magnetic field gives the shape memory polymer composite (SMPC) pre-deformation was studied, through on and off of magnetic field the two-way activation of SMPC was achieved. Shape memory effect of shape memory composite in magnetic field was studied. The SMPC was filled by nickel powder, and the nickel powder was treated by silane coupling agent. The Tg of shape memory composite was measured by dynamic mechanical analyzer. The surface element of treated nickel powder was analysized with XPS. The results indicated that the shape of composite filled by untreated nickel powder did not change in the magnetic field, while the composite filled by treated nickel powder was drawn in the magnetic field. The tensile stretch was decrease with the increase of nickel powder content in the shape memory composite. The addition of silane coupling agent onto nickel powder surface was helpful for the dispersion of nickel in polymer.
Nozzle-Type ELID Grinding Characteristics of Cemented Carbides
Authors: Yin Shao Hui , Tang Kun , Ohmori Hitoshi , Zeng Xian Liang , Chen Feng Jun , Wang Yu
Published: August 2010

This paper reports a systematic investigation of a nozzle-type ELID grinding characteristics of cemented carbides. Two groups of experimental scheme were carried on by using fine grain cast iron diamond wheel and nozzle-type ELID grinding apparatus. The grinding forces were measured by a dynamometer and the ground surfaces were characterized using scanning electron microscopy (SEM) and atomic force microscope (AFM). The influences of electrolytic and grinding parameters on grinding force were discussed. The material removal mode and micro-morphology characteristics were also analyzed.
The CMP by Polishing with GiP Dressed by BODD
Authors: Sung James C. , Tsai Ming Yi , Chou Cheng Shiang , Tso Pei Lum , Chen Ying Tung
Published: August 2010

Due to the continual improvement of CMP technologies, and the need for polishing delicate wafers at high speed, graphite impregnated pads (GiP) dressed by brazed organic dia mond disks (BODD) can double the throughput of wafer-pass at the reduced cost of ownership (CoO). The increased polishing rate is due to the act of nano graphite particles that absorb slurry. The nano graphite particles coated with chemical and abrasive can achieve high removal rate without causing scratches on the wafer. In addition, nano graphite particles do not stick to wafer surfaces, so they can be cleaned easily. BODD can uniquely dress GiP to create slurry channels so the pore free pad is not bottlenecked by slurry supply. This paper also demonstrated the low stress polishing by applying ultrasound during the CMP process.
Investigation of Semi-Fixed Abrasive Plate Wear Characteristics
Authors: Zhao Ping , Deng Qian Fa , Lv Bing Hai , Hang Wei , Wang Zhi Wei , Yuan Ju Long
Published: August 2010

In order to reduce or eliminate the surface defects caused by abrasive grains and improve the efficiency of ultra-precision processing, the technique of semi-fixed machining has been proposed for machining advanced ceramics. A semi-fixed abrasive tool (SFAT) has been manufactured; it has performances of semi-fixed machining technique. This document demonstrates wear characteristics of SFAT through experiments of machining silicon wafer. It showed that wet status or dry status of SFAT has greatly influenced wear characteristics of SFAT. Wear characteristic of SFAT presented mostly blockage and little grain-off occurred in dry status; mostly grain-off and little blockage presented in wet status.
On-Machine Method to Condition the Grinding Ability of Resin-Bond Wheels
Authors: Tani Yasuhiro , Kim Tae Won , Murata Junji , Zhang Yu , Sawayama Sho , Tsutanaka Kousuke
Published: August 2010

To reduce costs in the manufacturing and usage of grinding wheels, we investigate several methods of adjusting the sharpness of grinding wheels that involve heat treatment and irradiation by ultraviolet (UV) light. We confirm that heat treatment in a furnace of phenol-resin grinding wheels for aluminium leads to improved grinding ability of the wheels for stainless steel and also prevents swarf loading. Next, we clarify that treating the surface of grinding wheels by UV irradiation and heat blowing has a similar effect as heat treatment in a furnace. These treatments reduce the force ratio in surface grinding. Although UV irradiation and heat-blowing affect only the surface layer, heat treatment in a furnace affects the entire wheel. Therefore, thickness of the affected layer varies as a function of the UV-irradiation time. Finally, we applied this technique to other resin-bond wheels and found that the same effect is obtained for polyester-bond grinding wheels. However, heat treatment does not improve the grinding ability of epoxy-bond wheels with high heat resistance. In this case, UV irradiation proved to be an effective method.
Laboratory Comparison of Mini-Discs with Point-Attack Picks
Authors: Tiryaki Bulent , Gipps Ian D. , Li Xing S.
Published: August 2010

The selection of the cutter type is of crucial importance to maximise the advantages of mechanical rock excavation systems. Specific energy (SE), cutter forces, and rock properties are used to decide what type of cutter is most suitable for economical excavation of the rock based on laboratory rock cutting tests. This study is concerned with the preliminary results of an ongoing rock cutting program in which a mini-disc has been compared with a point-attack pick in laboratory linear cutting tests simulating a cutterhead on a Helidon sandstone block. Analysis of the preliminary results has shown that the mini-disc experienced lower mean cutting forces and was seven times more efficient than the pick in first layer cuts. However, the mini-disc had mean normal forces 1.5 times higher than the pick. Additionally, first layer cuts taken on the trimmed surfaces required more forces and SE than completely relieved cuts in pick cutting.
A Study on the Ductile Mode Cutting of Lithium Niobate
Authors: Shizuka Hiroo , Okuda Koichi , Nunobiki Masayuki , Li Wei , Inaoka Takanobu
Published: August 2010

This paper describes the cutting characteristics of lithium niobate, which is used for surface acoustic wave type micropumps, regarding the formation of micro grooves by direct cutting. Since lithium niobate is a brittle material with a strong crystal orientation dependency, significant differences were observed in the characteristics of the finished surface according to different directions of cutting. The ductile mode cutting of lithium niobate was found to be feasible with cutting depths of approx. 5 μm or less. Also, results of the study show the feasibility of the formation of minute grooves through the cutting of lithium niobate, using milling with an end mill.
Friction Phenomenon in Chemical Mechanical Polishing of Oxide Film
Authors: Tsai Ming Yi , Yang W.Z.
Published: August 2010

The friction phenomenon was investigated to explore the relationship between the diamond conditioner, polishing pad and wafer of oxide film in the chemical mechanical polishing (CMP) process. Two kinds of diamond conditioners (disk-A and disk-B) were used. Diamond disk-A used was traditional diamond conditioner containing random shaped diamond grits. Diamond disk-B used was made by sculpturing a sintered polycrystalline diamond to form identically shaped cutting tips. Experimental results reveal that friction force between disk and pad increases with dressing load. But friction force decreases with sliding speed due to increase of sliding speeds resulting in an increase of interface temperature. The coefficient of friction between wafer and pad initially increases with the dressing load, and then it starts to drop slowly with further increases of the dressing load. It was found that removal rate of the oxide film correlates well with the variation of the coefficient of force. In addition disk-B can produce a higher wafer removal rate under a low dressing load.
Tool Life and Surface Roughness of FCD 700 Ductile Cast Iron when Dry Turning Using Carbide Tool
Authors: Ghani Jaharah A. , Mohd Rodzi Mohd Nor Azmi , Othman Kamal , Che Haron Che Hassan
Published: August 2010

Machining is one of the most important processes in producing automotive component such as difficult-to-cut FCD700 cast iron grade. Efforts are continuously made to improve the machining technique for the benefit of human and environment. This paper presents an environmental friendly when turning FCD700 cast iron using carbide tool in the absent of coolant. The turning process was carried out in three medium of dry conditions i.e. without air, chilled air and normal air. The turning parameters studied were cutting speed (100-300 m/min), feed rate (0.1-0.4 mm/rev), and depth of cut (0.2-2.0 mm). Result shows that the average surface roughness (Ra) was greatly affected by the feed rate and the effect of depth of cut was negligible. Low Ra value was produced when using high cutting speed, especially at medium air temperature of 10 deg C. Whereas when turning at high depth of cut and high feed rate, the tool life was shorten drastically. In addition, the cutting speed was significantly affecting the tool life. The tool life was found to be inversely proportional with the cutting speed. The longest tool life was obtained at cutting speed of 100 m/min, feed rate of 0.15 mm/rev, depth of cut of 0.2 mm and temperature of -2 deg C. Generally, chilled air at temperature of -2deg C will increase the tool life, but the Ra obtained was deteriorated when compared at higher temperature of chilled air and without air cutting environment. Therefore, these findings can be used a guide depending on the preference of the user, either to obtain a better tool life or Ra value.
Fabrication of Micro Shapes by EDM with Micro Electrodes Generated in Turning Operation
Authors: Miura Kohichi , Takahashi Masayuki , Yamada Takazo , Lee Hwa Soo
Published: August 2010

In order to fabricate micro geometrical shapes by EDM process, micro electrodes as tools are needed. At present, micro electrodes are generated by grinding and/or on-machine EDM operations and then it is well known that efficient productivity of micro electrodes cannot be realized. In this study, a new micro EDM method is proposed, in which, micro electrodes generated in turning operation controlling thrust forces to be zero are utilized. As the results of some experimental evaluations, productivities and availabilities of proposed micro EDM are confirmed.