bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical Modeling of the Fracture Toughness of Phenol Formaldehyde Composites Reinforced with E-Spheres
Authors: Ku H. , Xiang W. , Pattarachaiyakoop N.
Published: September 2009

The fracture toughness of SLG filled phenolic composites have been determined by short bar tests. It is expensive to prepare the samples for the tests. Therefore, it is necessary to develop a mathematical model that will predict the fracture toughness of particulate filled phenolic composites. Mathematical models for tensile strength, Young’s modulus are available but not for impact strength and fracture toughness. There is no sign that it can be built up from simple mathematical model; polynomial interpolation using Lagrange’s method was therefore employed to generate the fracture toughness model using the data obtained from experiments. From experiments, it was found that the trend of the fracture toughness of the samples cured conventionally was similar to that cured in microwaves; it is therefore possible to predict the fracture toughness of the samples cured in microwaves from shifting the mathematical model generated for fracture toughness of samples post-cured in conventional oven. The shifted model represented the fracture toughness of the samples cured in microwaves vey well.
A Study on Process-Induced Warpage of Curing Mold of Composite Structures
Authors: Yue Guang Quan , Zhang Bo Ming , Du Shan Yi , Dai Fu Hong , Zhang Cheng , Liang Xian Zhu , Wang Yong Gui
Published: September 2009

Framed curing mold is subjected to an uneven thermal load, gravity force and the pressures from composite parts and auxiliary tools during autoclave processing of thermosetting composite structures. And those loads induce the warpage of framed-mold. The warpage of framed-mold during autoclave processing influences dimensional precision of composite parts. In the present work, a three-dimensional finite element model for prediction of the warpage of framed-mold during autoclave processing has been developed. This model solved the coupling problem between the deformation and the temperature distribution of framed-mold and allows analysis of all major identified deformation influencing factors. And numerical predictions compare quite well with experimental measurements. A parametric study was performed using FEM program to examine the effect of varying the thickness of framed-mold, the shape and the dimension of mold vents.
First-Principles Calculations on the Geometry and Electronic Structure of Rutile TiO2 (110) Surface
Authors: Su Hong Bin , Yang Ping , Wang Jin Biao , Huang Nan
Published: September 2009

In this paper, both geometrical and electronic properties of rutile TiO2 (110) surfaces have been investigated using First-Principles Density-Functional calculations with CASTEP code, the model of stoichiometric surface is a (2x1) super-cell which has 12 atomic-layer slabs with the bottom 6 held fixed, the bridging-oxygen vacancy surface has been constructed by removing a neutral bridging oxygen atom from this surface.
For the stoichiometric surface, the atom relaxations are: Ti6f (+0.2865Å), Ti5f (-0.1039Å), O3f (+0.2433Å) and Ob (+0.0075Å), we find no reconstruction and no surface states in the band gap, the density of states (DOS) is similar to the bulk except the lower conduction band intensity, in accord with recent experiments. Whereas, as a result of bridging-oxygen vacancy, the atom relaxations exchanged and reconstruction occur. The 2 excess electrons left behind removal of one bridge O atom are localized on the Ti-t2g conduction band orbitals, convert some of the Ti4+ ions into Ti3+ ions and result a compensatory shift in the Fermi level. The band gaps we calculated for stoichiometric surface is similar to the bulk, but its increase can be found for Ob vacancy surface.
The Gradual Damage Analysis for the Two-Dimension Unit Cell of the Composite
Authors: Yu Jia , Shi Rong Rong , Liu Yi Zhuo
Published: September 2009

In this paper, the finite element software——ABAQUS Computing Platform is used to build two-dimension unit cell of the composite one-way slab model. Compute it by two ways: 1)supposing that the fiber and matrix are elasticity, but they are different for material parameters, and this assumption is generally used. It can be computed directly in the ABAQUS software; 2)supposing that the fiber is elasticity, but the matrix is the viscoelasticity. For the matrix, its viscoelastic character can be simulated by the solid constitutive model with three parameters. The maximum stress (MS) judgment criterion is used to determine whether the matrix is destroyed. If the matrix is destroyed, the stiffness of the whole matrix would be degraded by means of the degradation factor, which determined by the Camanho parameter degradation pattern. Compare the stress and strain curves got through the numerical simulation and through the experiments, and find that the second situation is similar to the experiment’s result.
Research on LSCMCo-CDC Composites as Improved Anode Material for IT-SOFC
Authors: Chen Xiu Hua , Ma Wen Hui , Yu Jie
Published: September 2009

La1-xSrxCr1-yMnyO3-δ(LSCM) has unique advantages over the traditional anodes for it’s stability and high catalytic activity being an anode of solid oxide fuel cell(SOFC). Doped cerium material and Co element are used to improve the conductivity both in oxidative and reductive conditions. La0.7Sr0.3Cr0.5Mn0.5-xCoxO3-δ-Ce0.8Ca0.2O2(LSCMCo-CDC) composite anode materials are synthesized in one-step by glycine nitrate process(GNP). X-ray diffraction patterns(XRD), scanning electron microscopy(SEM) and energy dispersive X-ray spectroscopy(EDS) are used to characterize the powders. The conductivity of LSCMCo-CDC increases with increasing the quantity of Co when the temperature is above 750°C, and the maximum values are 10.5 Scm-1 and 0.7 Scm-1 of LSCMCo0.15-CDC at 800°C in air and H2 atmosphere, respectively. It’s conductivity in intermediate temperature have been promoted obviously comparing to that of LSCM-CDC and LSCMCo. Good chemical compatibility between LSCMCo-CDC and La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM) is confirmed by XRD results.
First-Principles Study of the Electronic Structure and Spontaneous Polarization of PbZr0.4Ti0.6O3
Authors: Zhao Qing Xun , Geng Bo , Guan Li , Li Qiang , Ma Ji Kui , Wei Da Yong , Guo Jian Xin , Liu Bao Ting
Published: September 2009

Density functional theory plane-wave pseudopotential with the general gradient approximation (GGA) was used to investigate electronic structural properties and the bulk spontaneous polarization (Ps) of PbZr0.4Ti0.6O3. It is found that there are strong hybridizations between Ti 3d states or Zr 4d states and O 2p states, which can reduce short-range repulsion in atoms and enhance the stability of the ferroelectric phase of PbZr0.4Ti0.6O3. Compared with cubic ideal structure, the calculated internal electronic structural data indicate that the slightly distorted O6 octahedrons around the central Ti and Zr atoms change to the Ti-O5 and Zr-O5 pyramid in the optimized structure, respectively. The major contribution to the spontaneous polarization along [001] comes from the stronger interaction along the c axis between the Ti and O rather than the Zr and O ions. The Pb atom’s relative displacement of oxygen octahedral implies that the Pb-O bonding interaction is also a key factor impacting the ferroelectricity of PbZr0.4Ti0.6O3. A theoretical spontaneous polarization of 0.78 C/m2 was computed in the tetragonal PbZr0.4Ti0.6O3 along [001] direction, consistent with the single crystal experimental data.
Experimental and Numerical Study of the Influence of a Low-Frequency Electromagnetic Field on the As-Cast Structure of Horizontal Direct Chill Casting Aluminum Alloy Slab
Authors: Zhao Zhi Hao , Cui Jian Zhong , Zhu Qing Feng , Wang Gao Song
Published: September 2009

The influences of low frequency electromagnetic field on the as-cast structure of horizontal direct chill casting aluminum alloy slab were experimental and numerical studied. The results of numerical analysis show that the interaction of the low-frequency electromagnetic field and the melt can generate an electromagnetically induced forced flow in the melt, which, in turn, changes flow pattern and temperature field in the mold. the as-cast structure of slab can be greatly improved by the changes of flow pattern and temperature field. The results of experimental analysis show that the grains of low frequency electromagnetic casting (LFEC) are fine, uniform, equiaxed, rosette-shaped; the surface of the slab of LFEC has no cold shut and less exudations. Moreover, the low-frequency electromagnetic field can improve the distribution of solute elements in the slab. The macrosegregation such as negative segregation and gravity segregation were reduced, which results in the homogenous distributions of the solute elements over the cross-section of the slab.
A Study on the Crack-Controlled Layer of UHTCC in Functionally-Graded Composite Beams
Authors: Li Qing Hua , Xu Shi Lang
Published: September 2009

This paper presents research work relating to design method and mechanical properties of functionally-graded composite (FGC) beams, in which a kind of strain hardening material UHTCC is used as a replacement for the concrete material that surrounds the longitudinal reinforcements. According to mechanical models of materials and a series of assumptions, a simplified design method of such FGC beams is proposed. On the basis of superposition, the determination and the influencing factors of the thickness of UHTCC layer in FGC beams is discussed. Compared with theoretical and experimental results, simplified method shows conservation and guarantees the safety of structures. During the whole flexural loading process, it is found that the opening of cracks in flexural members can be greatly restricted by the introduction of UHTCC. The possibility of steel corrosion therefore can be evidently reduced.
Numerical Study on the Mechanical Behavior of Aluminum Foam Material Using CT Image
Authors: Chung Hyup Jae , Rhee Kyong Yop , Han Beom Suck , Ryu Yong Mun
Published: September 2009

In this study, finite element analysis was made to predict the tensile and compressive behaviors of aluminum foam material. The predicted tensile and compressive behaviors were compared with those determined from the tensile and compressive tests. X-ray imaging technique was used to determine internal structure of aluminum foam material. That is, X-ray computed tomography (CT) was used to model the porosities of the material. Three-dimensional finite element modeling was made by stacking two-dimensional tomography of aluminum foam material determined from CT images. The stackings of CT images were processed by three-dimensional modeling program. The results showed that the tensile stress-strain curve predicted from the finite element analysis was similar to that determined by the experiment. The simulated compressive stress-strain curve also showed similar tendency with that of experiment up to about 0.4 strain but exhibited a different behavior from the experimental one after 0.4 strain. The discrepancy of compressive stress-strain curves in a high strain range was associated with the contact of aluminum foam walls broken by the large deformation.
Modeling and Optimization of Nanomechanics of Diamond-Like Carbon by MPCVD Using Response Surface Methodology
Authors: Chen Jung Sheng , Ting Ku En , Wang Hui Ching
Published: September 2009

Diamond-like carbon (DLC) films have attracted great interest due to their outstanding mechanical, biocompatibility, thermal, optical and electrical properties. The DLC films can be produced by microwave plasma chemical vapor deposition (MPCVD) using Argon, methane and hydrogen mixed gases. The film properties depend strongly on the experimental parameters such as substrate temperatures; microwave power, process pressure and hydrogen concentration (H2/Ar+CH4+H2). In this study, the properties of nanomechanics of DLC films with various experimental parameters are firstly discussed which include hardness and Young’s modulus characterizing by depth-sensing nanoindentation technique. The nanoindentation is an excellent method for measuring nanomechanical properties of both bulk and thin films. The probe was conducted using a Berkovich diamond tip. To find the optimized process parameters, the statistical and mathematical response surface methodology (RSM) is used to model and analyze the effect of substrate temperature (T), microwave power (W), process pressure (P) and hydrogen concentration (H) on the properties of nanomechanics of DLC films. The central composite experimental design (CCD) is used to evaluate the interaction parametric effects of multiple experimental variables on process response (hardness and Young’s modulus). The predictive quadratic model proposed herein considering the analysis of variance (ANOVA) are proved to fit and predict values of the hardness and Young’s modulus close to those readings recorded experimentally. The most significant influential factors for maximizing the hardness and Young’s modulus have been identified from the ANOVA table. The RSM technique is demonstrated to be a powerful tool in exploration of the manufacturing parameters space of complex physical process of DLC films deposition by MPCVD.
Numerical Study on Damage Response of Ship Composite Armor Structures to Contact Underwater Explosion
Authors: Yang Li , Wang Yu , Zhang Qing Ming , Du Zhi Peng
Published: September 2009

As a new type of protection design, composite armor structures have good performance in impact resistance, and have been widely used in ship structure protection. Due to its academic value and potential applicability, the dynamic characteristics of ship composite armor structures were studied in this paper. The whole process of the shaped charge’s explosion and penetration, and the ship composite armor structures’ damage response were described. According to the numerical simulation with Ansys-Autodyn, it was found that the ship composite armor structures were damaged not only by the explosively formed projectile but also by the detached shock wave in the conditions of contact underwater explosion and the thickness of composite armor structures was the main factor effecting the impact resistance properties.
First-Principles Calculations of Structural and Elastic Properties of Hexagonal Boron Nitride
Authors: Xiao Liu , He Wen Jun , Yin Yan Sheng
Published: September 2009

The lattice parameters, five independent elastic constants and the bulk modulus B on the applied pressure of hexagonal boron nitride (h-BN) are calculated by using a first-principles pseudopotential method. The calculation results are in good agreement with the experimental and theoretical values. It is found that the most stable structure of h-BN corresponds to the axial ratio c/a of about 2.652.
Micromechanical Modeling of the Effect of Progressive Damage on the Tensile Behavior in Fiber-Reinforced Polymer Composites
Authors: Wang Fang , Wei Yu Qing , Chen Zhi Qian
Published: September 2009

In this article a methodology based upon micromechanical analysis of multiple damage events is developed to predict stress-strain response and failure behavior of fiber-reinforced polymers composites under tensile loading, by considering the effect of variations in fiber strength and local shear failure of the matrix. A simulation scheme coupled with Monte-Carlo method including these failure mechanisms is proposed to investigate failure process and determine ultimate strength of the composites. It is shown that the size dependence of composite ultimate strength is dominated by fiber strength statistics and stress distribution due to progressive microdamage.
Synthesis of Al8B4C7 from Al/ Na2B4O7•10H2O/C Mixed Powders
Authors: Deng Cheng Ji , Zhou Wei , Zhu Hong Xi , Yu Yi
Published: September 2009

Al8B4C7 should be a successful antioxidant in carbon-containing refractories, and it have excellent hydration resistance. In this paper, the synthesis process of Al8B4C7 and the mechanism have been studied. Aluminum, borax and activated carbon powders were used as starting material. Using borax as the source of B, can greatly reduce the cost of synthesis. Our experiments showed that use these materials can synthesize Al8B4C7, and the final product is closely related to the temperature and ratio of raw materials. Al8B4C7 appeared at about 1300°C, and with the temperature increased, more Al8B4C7 was generated in the heating samples. The phase compositions of these samples heated at 1700°C were Al8B4C7, Al2O3, Al4O4C and Al2OC.
Experimental Analysis and Performance Evaluation of Magnetorheological Damper under High Impact Load
Authors: Zhou Hao Jun , Wang Jiong , Qian Su Xiang , Jiang Xue Zheng
Published: September 2009

Its primary purpose of this study is to provide a comprehensive investigation on its dynamic performance of MR damper under high impact load. A test had been firstly done in order to identify its high shear viscosity of MR fluid. Then, its thermal performance of MR damper under high impact load is analyzed in order to aid its structure design of MR damper intended for weapon recoil mechanisms applications and improve its performance of elimination of heat. Further, Experimental analysis and performance evaluation of MR damper under impact load have been done by numerical simulation and hardware-in-the-loop simulation, including its acceleration response and pressure response of back cavity under different flow coefficient and the same inputting current, and its acceleration response and pressure response of back cavity under the same flow coefficient and different inputting current. Based on these simulation results, the shear-thinning phenomena and its dynamic response under saturated input current are analyzed and some useful conclusions are made. Finally, experimental results indicated that the developed MR damper under high impact load can achieve a good controllability for recoil applications.
Microstructural Morphology and Phase Structure of Rapidly Solidified Hypereutectic Al-Si Alloys
Authors: Wang Ai Qin , Li Ji Wen , Xie Jing Pei , Wang Wen Yan
Published: September 2009

In the present work, rapidly solidified hypereutectic Al-Si-Cu-Mg alloys strips was prepared by single roller melt-spinning method. The microstructures, phase and morphology characteristics of the resultant strips were characterized by means of SEM, TEM and XRD technique. The results show that the grains are refined after rapid solidification processing, and the micro-nanocrystals are formed. Compared with equilibrium solidification, the microstructures are changed obviously. The nucleation and growth of primary silicon are suppressed and primary silicon can not deposited, meanwhile, α-Al phase is nucleated which prior to eutectic. Therefore, the microstructures become into the metastable state. The microstructures of the strips are composed of primary micro-nanostructure α phase and feather-needles-like (α+Si) eutectic which set in the α phase. The mechanism of the formation for microstructures of melt-spinning Al–Si alloy have also been discussed.
Magnetic Properties and the Giant Magneto-Impedance in Joule-Heated Glass-Covered Co-Based Microwire
Authors: Tian B. , Wang L.H. , Zhou L.Y.
Published: September 2009

The influence of DC current annealing on magnetic properties and the frequency dependence in the range from 0.1 to 20 MHz of the giant magnetoimpedance effect (GMI) of glass-covered amorphous microwires were investigated. Under a certain annealing condition (10 min annealing with applied current Ia=110 mA), the maximum change of impedance was about 200% with a maximum slope sensitivity of 0.26%/Am-1 . Further treatment with increased current resulted in a decrease of the maximum MI ratio. Meanwhile, annealing can produce short-range order relaxation and consequently improves the sample's soft magnetic properties. We also found that the GMI ratio increased due to the enhanced induced anisotropy with increasing current under the same Joule energy.
The Microstructure of The Semi-Solid ZL201 Alloy Obtained by Near-Liquidus Electromagnetic Casting and the Fine Mechanism
Authors: Ping Wang , Tian Liang
Published: September 2009

Electromagnetic field was applied by ZL201 alloy melt when it was cast in near-liquidus temperature. The effects of electromagnetic stirring power and cooling condition on microstructure were studied. The result showed that, by using electromagnetic field at near-liquidus temperature, alloy microstructures were the fine and uniform non-dendritic grains. Moreover, with current strength increasing and cooling condition strengthening, the trend of the fine and uniform reinforced. When ZL201 alloy was cast at low superheat, the radius of the critical nucleus reduced. Under electromagnetic field, the melt temperature gradient decreased, and the formation of quasi-solid phase atom clusters in the melt was promoted. So the nucleation rate increased and microstructures were fine and uniform. Electromagnetic field made solute uniform, and the rapidity of nucleus growing up in all directions was almost at the same rate, therefore, the grain grew up near-spherical shape.
Effect of Ti, Al and Mg Addition on the Impact Toughness of Heat Affected Zone in Low Carbon Steel
Authors: Ma Jiang Hua , Zhan Dong Ping , Jiang Zhou Hua , He Ji Cheng
Published: September 2009

In order to understand the effects of deoxidizer such as aluminium, titanium and magnesium on the impact toughness of heat affected zone (HAZ), three low carbon steels deoxidized by Ti-Al, Mg and Ti-Mg were obtained. After smelting, forging, rolling and welding simulation, the effects of Al, Ti and Mg addition on the impact toughness of HAZ in low carbon steel were studied. The inclusion characteristics (size, morphology and chemistry) of samples before welding and the fracture pattern of the specimens after the Charpy-type test were respectively analyzed using optical microscope and scanning electron microscopy (SEM). The following results were found. The density of inclusion in Ti-Mg deoxidized steel is bigger than Ti-Al deoxidized steel. The average diameter is decreased for the former than the latter. The addition of Ti-Mg can enhance the impact toughness of the HAZ after welding simulation. The maximal value of the impact toughness is 66.5J/cm2. The complex particles of MgO-TiOx-SiO2-MnS are most benefit to enhance impact toughness. The improvement of HAZ is attributable to the role of particle pinning and the formation of intergranular ferrite.
Synthesis and Characterization of Thermotropic Liquid Crystalline Polyesters/Glass Fiber by In Situ Process
Authors: Zhang Chuan Ji , Huang Zhi Xiong
Published: September 2009

Liquid crystalline polyesters containing central biphenylene moiety in the mesogenic unit with ester linkages to the different lengths of flexible spacers were synthesized using melt polycondensation reaction. Glass fiber, as a reinforce, was meltpolymerized with 4-acetoxybenzoic(ABA),4,4＇-diacetoxybiphenyl and terephthalic acid(TA) to make TLCPs with a good mechanical properties. All the obtained compounds were characterized by conventional spectroscopic methods. The thermal behavior of the polymers has been characterized using polarized optical microscopy and differential scanning calorimetry. The effect of monomer structure and mechanical properties has been investigated on the prepared polyesters and is also compared with that of the analogous polyester by other processing mode. Optical microscopy showed a highly threaded liquid crystalline texture to a high birefringent Schlierene texture characteristic of the nematic phase for all polyesters. DSC experiments were also found in accord with mesophase formation. The melting points of polymers having a central 4,4’-biphenyldicarboxylate residue have two broad endotherms. The glass transition temperature values of polyesters are not effect by the glass fiber. According to the SEM result showed that the composite had strong fiber-matrix adhesion. From the mechanical test result, it showed that TLCP are reinforced by rigid fiber further improvement of properties depending on fiber content, fiber fabric construction, fiber type. The mechanical properties of GF/TLCP had been improved greatly as the content of glass fiber was increased,but GF/TLCP mechanical properties do not improve remarkably as glass fiber content more than 30wt%.The effect of copolymerization with added glass fiber in synthesis process is compared with that of the anlogous homopolyesters by other processing mode. Our finding shows that the copolymers exhibit reduced technical process and maintained mechanical properties.
Study on the Feasibility of Bacterial Cellulose as Tissue Engineering Scaffold
Authors: Wang Ping , Shi Yi , Jia Yuan Yuan , Zheng Jing Tong , Wang Zong Liang , Chen Yan Yan , Zhou Yu Lai
Published: September 2009

OBJECTIVE: As a kind of nanometer natural material, bacterial cellulose (BC) has been widely used in the field of food processing, paper making, pharmaceutical science, etc. In recent years, it is found that there is a good application potentiality of BC used in the medical science, especially in the field of regeneration medicine. There are some reports about BC being used in tissue engineering. It is of great necessity to investigate its tissue compatibility. In this research, the cell compatibility of BC was studied by using the method of cell-culturing combined with rat adipose- derived stem cells (ADSCs) as the seed cells. MATERIAL and METHODS: BC membranes were prepared by Key Laboratory of Industrial Microbiology, Ministry of Education, Tianjin University of Science and Technology. The average pore size and porosity of it were 0.8-3.5μm and 93％, respectively. The ADSCs were isolated from the fat pad located in pars inguinalis of 3-weeks Wistar rats by using type II collagenase and then cultured using DMED medium contained 10% new-born calf serum. The status of cell growth was observed everyday. The cell growth curve was determined by MTT method and stem cell phenotype was identified by flow cytometry. Cells in exponential phase of growth were planted on the surface of BC membrane which had been sterilized beforehand by steam at 121°C for 20 min at cell density of 3.0×105cells/mL. The cell-BC compound was cultured by using DMED medium contained 10% new-born calf serum. The growth status and the biological characterization of ADSCs cultured on the BC were determined at different culture time. RESULTS: Most ADSCs primary cultured in vitro showed fusiform shape when they were cultured for 72 hours. The amount of the cells increased along with the culture time and confluenced at 7 days. The exponential phase of growth of primary cultured ADSCs in vitro appeared when they were cultured for 3 to 9 days. The result of flow cytometry showed that ADSCs could express the stem cell symbol. The portait section of cell-BC compound were made after 10 days cultured in vitro. It was shown that ADSCs compact grew on the surface of BC. CONCLUSION: It is indicated that ADSCs grew on the BC membrane still retain the biological activity of stem cell and BC has good biocompatibility. It might be further studied for BC as tissue engineering scaffold.
Instability of Functionally Graded Panels with Structural Damping under Supersomic Flow
Authors: Lee Sang Lae , Kim Ji Hwan
Published: September 2009

In this study, thermal post-buckling behaviors and linear flutter analysis of Functionally Graded(FG) panels with structural damping under a supersonic airflow are investigated. First-order shear deformation theory (FSDT) is applied to model the panel, and the von-Karman strain-displacement relations are adopted to consider the geometric nonlinearity. In addition, the damping is modeled as the Rayleigh damping, and the first-order piston theory is applied for the supersonic aerodynamic load.
Synthesis, Structure and Electrochemical Behavior of a Supramolecular Compound
Authors: Lin Zhi Feng , Zhang Shu Fang , Zhang Dun
Published: September 2009

A supramolecular compound, Co(C5H4NCOO)2(H2O)2∙2H2O was hydrothermally synthesized and characterized by elemental analysis, infrared spectra, UV-vis spectra. Elemental analysis result shows that the mass percent of C is 38.36%; H, 4.32% and N, 7.50%. Infrared spectra show that the main absorption peak is near 3396 cm-1, which is attributed to the O-H stretching vibration absorption. Also there are some absorption peaks at 1599, 1551, 1420, 1384 cm-1, which are attributed to the pyridine vibration absorption. UV spectrum for the compound shows strong absorption peaks at 203 and 259 nm, which are similar to isoniazid. X-ray diffraction data indicate that the compound is monoclinic, P21 / c space group. The cyclic voltammograms indicate that the compound decreases the rate of oxygen reduction reaction (ORR) and induces the ORR more difficult in aqueous solutions. The electrochemical behavior suggests that the compound possesses the potential application for corrosion in aqueous environment.
Solid Reaction and Microstructure of Interface of 3D Meshy SiCn/Cu Composite
Authors: Li Jing Yang , Ru Hong Qiang
Published: September 2009

The SiC/Cu composite was prepared by the method, which is patented in China, casting the metal into the SiC skeleton in a special furnace at 1160°C by pressure, caused by pressure difference between pressured gas and vacuum. During the preparation, the SiC decomposed. The carbon precipitated and the silicon, which has well affinity with the metal, formed silicon-copper compounds as Cu4Si, gathering in the silicon-copper interface area, identified by means of EDS and XRD. The mechanism of the solid reaction was discussed and the microstructure and morphology was studied by means of optical devices, SEM, EDS and XRD as well. And the diffusion coefficient was calculated.
Fracture Behavior of Particle Reinforced Metal Matrix Composites
Authors: Song Wei Dong , Liu Hai Yan , Ning Jian Guo
Published: September 2009

SEM experimental system was employed to investigate the fracture behavior of particle reinforced metal matrix composites (91%wt tungsten alloys) by in-situ experiments. The fracture patterns of tungsten alloys under tensile loading were examined. Multi-particle unit cell models containing some important microstructure characteristics of tungsten alloys were established. By using fixed point iteration method, the displacement constraint conditions were applied on the multi-particle unit cell and the mechanical properties of tungsten alloys under tensile loadings were simulated. Comparison of the experimental results and the numerical predictions shows a good agreement between them, verifying the rationality of the FE models using the fixed point iteration method.
Micro Electrochemical Polishing of TiNi Alloy for Medical Stent
Authors: Shin Tae Hee , Baek Seeung Yub , Lee Eun Sang
Published: September 2009

The medical stent is using widely for a surgical operation, because it can reduce the pain of cardiac. When it was developed initially, medical stent was made of stainless steel, however, the TiNi alloy is widely using presently instead of stainless steel. Because, TiNi alloy has not only super elasticity and Smart Material Effect (SME) but also excellent organism compatibility. For these reason, the TiNi alloy is currently highlighted for medical stent material better than other materials. Nevertheless, this TiNi alloy is not suitable to traditional machining process. When the traditional machining process is conducted to the TiNi alloy, it cannot be discharged the machining heat and inner stress. Also, traditional machining process makes a lot of microscopic burrs on the TiNi alloy surface. This microscopic burrs and the rough surface makes injury on vascular, so, it should be necessary non-traditional machining process without defect of traditional machining.
In this paper, microscopic burrs on TiNi alloy for medical stent are removed, and surface roughness of the medical stent is evaluated by Electrochemical Polishing (EP) which is one of the non-traditional machining.
Polyaniline/Graphitenanosheets/Eu3+Nanocomposite: Synthesis and Characterization
Authors: Mo Zun Li , Wang Guo Rui , Wu Ying Bing , Niu Gui Ping , Feng Chao , Wang Jun
Published: September 2009

A novel structure of nan0Composite consisting of conducting Polyaniline (PANI), graphite nanosheets (NanoGs) and Eu3+ was synthesized through emulsion polymerization. NanoGs were prepared via powdering the expanded graphite with the aid of sonication in aqueous ethanol solution. Then NanoGs and rare earth ions (Eu3+) were directly organised with sonication, using p-toluene-sulfonic acid (P-TSA) as an emulsifier and dopant, (NH4)2S2O8 as inducing reagent and the polymerization of aniline monomer simultaneously. The product was characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), Fouier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA). From the thermogravmetric analysis, the introduction of NanoGs and rare-earth ions (Eu3+) exhibited a beneficial effect on the thermal stability of pure PANI.
Coprecipitation Synthesis and Negative Thermal Expansion of R2Mo3O12 (R = Y, Yb)
Authors: Yang Hai Tao , Lin Wei Lin , Shang Fu Liang , Huang Yuan Hui , Gao Ling
Published: September 2009

In this research, powders of Y2Mo3O12 and Yb2Mo3O12 were successfully synthesized by liquid phase coprecipitation, followed with a heat treatment at 750°C for 6h. X-ray diffraction (XRD) analysis indicated that the Y2Mo3O12 and Yb2Mo3O12 were single orthorhombic structure with the space group of Pbcn. Negative thermal expansion properties of Y2Mo3O12 and Yb2Mo3O12 were studied with high temperature XRD analysis. The thermal expansion coefficients of Y2Mo3O12 and Yb2Mo3O12 were calculated to be -5.943×10-6K-1 and -6.237×10-6K-1 respectively.
Electrical Behavior of SiCp Reinforced Copper Matrix Composites by Hot Pressing
Authors: Wang Chang Chun , Min Guang Hui , Kang Suk Bong
Published: September 2009

SiCp reinforced copper matrix composites with the reinforcement content of 30-50vol. % were fabricated by hot pressing using Cu-coated and uncoated SiC powder. And the microstructure and electrical conductivity of the composites were also studied. The results showed that with the increasing of SiCp particle size, the electrical conductivity of the composites also increased. And the oxides in the composites can decrease the electrical conductivity of the composites obviously. The electrical conducting property of the composites can be improved by the copper coating layer and suitable annealing treatment. It provided important data for the application of SiCp/Cu composites as electronic packaging materials.
Research on Heat Treatment Process of Foam Glass Prepared by Titania-Bearing Blast Furnace Slag
Authors: Yang He , Ma Ming Long , Gao Ming Lei , Xue Xiang Xin , Tang You Quan
Published: September 2009

Foam glass insulation materials were made by using titania-bearing blast furnace slag. Heat treatment process including foaming temperature, foaming time and heating rate were studied and their parameters were determined. First of all, heat treatment process parameter was determined by single factor experiment. Second, optimum process parameters of heat treatment process were obtained by the optimization of orthogonalization procedure. The results showed that foaming temperature has a remarkable effect on sample pore structure ；Foaming time has a less effect on pore distribution but its effect on the diameter of the pore is obvious; Heating rate has a less effect on the diameter of the pore. The magtitude of impact of heat treatment on glass properties arrange in an order of foaming temperature, foaming time and heating rate. The Optimal parameters of heat treatment are that heating rate ,foaming temperature and foaming time are 12°C/min，900°C, 15min respectively ; After preheating, sintering, foaming and foam stability and annealing heat treatment process, an amorphous foam glass with uniform pore size was obtained. Its thermal conductivity coefficient, the bulk density, compressive strength and average diameter are 0.131w / m ∙ k, 445.8 kg/m3, 2.8MPa, 4.78mm respectively. This kind of material can be widely used in building, chemical and shipbuilding industry as thermal insulation, sound absorption, corrosion-resistant and floating materials.
Titania-bearing blast furnace slag is solid waste generated from vanadium-titanium magnetite by the blast furnace smelting, which is accumulated without being utilized. At present, Titania-bearing blast furnace slag is mainly used for cement concrete admixture, preparation of photocatalytic materials, extraction of titanium dioxide etc [1-2].Foam glass has been playing a more important role in low-temperature thermal insulation and moisture-proof anticorrosive projects field, and getting more economic benefits in energy saving and technology field. At present, the stuff for preparing foam glass is solid waste including waste glass, fly ash, slag, or natural minerals such as ash, mica, perlite etc. Foaming agent is usually selected from Carbon and carbonate [3-6]. In this paper, foam glass insulation materials were made by using titania-bearing blast furnace slag-based stuff. The effect of heat treatment process on foam glass performance was studied in a bid to find a new way to utilize titania-bearing blast furnace.
Structure and Properties of Epoxy Resin/Poly (aryl ether ketone) Blends Cured with 4,4'-Diaminodiphenylmethane
Authors: Zhou Jian Gang , Zeng Li Ming
Published: September 2009

The study on bisphenol A epoxy resin (EP)/4,4'-Diaminodiphenylmethane (DDM) system modified with poly(aryl ether ketone) (PEK-C) by the method of melt blending process is reported. The microscopic phase structure and morphology of impact fractured surface were observed by SEM, the phenomenon of microscopic phase separation and heat resistance property were studied by DMA. The results showed that PEK-C can disperse in the blends in the form of nanometer size (<100nm) particles or in the form of molecular size when the content of PEK-C lower than 10%, and the nano-particles are uniformly dispersed in the blends. The rough region of impact fractured surface with PEK-C modified sample is larger and more obvious, which indicated that toughness of the blends has been improved. The modified system has microscopic phase separation characteristics with higher content of PEK-C, as the same observed result of SEM, the glass transition temperature (Tg) of the blends moves towards higher temperature with the increasing content of PEK-C and the property of heat resistance has been improved.
Influence of Doped Mn, Cu, Ni and Fe on Electrical Properties of SrTiO3 Ceramics
Authors: Wang Ning Zhang , Sha Sha , Ma Yu Tian
Published: September 2009

MnCO3, CuO, NiO and Fe2O3 doped SrTiO3 multifunction ceramics were fabricated firstly. The microstructure and electrical properties were investigated. The results show that MnCO3 doped ceramic and CuO doped ceramic possess relative higher resistivity (ρ),nonlinear coefficient (α), varistor voltage (V1mA) and relative lower dielectric constant (ε),dielectric loss (tgδ) in contrast with NiO doped ceramic and Fe2O3 doped ceramic with the same contents under the same sintering conditions. The electrical properties among the ceramics doped are different due to the different behaviors of Mn,Cu,Ni and Fe acceptor dopants during the sintering course.
Influence of DC-Joule Heat on Giant Magneto-Impedance of Co-Based Melt Extraction Wires
Authors: Zhang Shu Ling , Xing Da Wei , Wang Huan , Xin Xin , Sun Jian Fei
Published: September 2009

Co68.25Fe4.5Si12.25B15 naked amorphous wires of 60μm in diameter are prepared by melt extraction technology and annealed by DC-Joule heat at current from 40mA to 250mA for 10min. Impedance response is measured at low frequencies(≤13MHz) using HP4192 impedance analyzer. We get better GMI effect by heating wires at 60mA and 180mA.The connection between GMI response and transformation of structure under different heat current has been discussed. After proper heat treatment, magneto impedance response is strong even at 0.5MHz with GMI amplitude of 193.1% and field sensitivity of 59.4%/Oe. The maximum △Z/Z reaches 476.9% and the largest field sensitivity is up to 91.8%/Oe. These results indicate proper annealed Co-based melt extraction wires are suitable for high sensitivity sensor applications.
Structure and Properties of Hydrogen-Charged Electrochromic Nb2O5 Ceramics
Authors: Ding Ming Jian , Chen Wan Ping , Gu Yan Hong , Wang Yu
Published: September 2009

Nb2O5 ceramic pellets were prepared through sintering and hydrogen was introduced into Nb2O5 pellets through a process known as electrochemical hydrogen charging, in which Nb2O5 acted as the cathode in a 0.01 M NaOH solution. The color of Nb2O5 was found dramatically darkened after the treatment while X-ray diffraction indicated that there was no change in the crystal structure. I-V and R-T measurements showed that the resistivity was greatly decreased after hydrogen charging and the resistivity exhibited a negative-temperature-coefficient (NTC). It was proposed that hydrogen can be incorporated into Nb2O5 lattice and occupies at some interstitial site. Nb5+ of Nb2O5 is partially reduced to Nb4+ by hydrogen and the NTC-type conduction results from electron transfer between Nb5+ and Nb4+ through a hopping mechanism.
Synthesis and Property of Y-Shaped Thermoresponsive Block Copolymers
Authors: Tang Xin De , Liang Xiao Chano , Han Nian Feng
Published: September 2009

Novel Y-shaped amphiphilic block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide), PEG-b-(PNIPAM)2, were successfully synthesized through atom transfer radical polymerization (ATRP). A difunctional macroinitiator was prepared by esterification of 2,2-dichloroacetyl chloride with poly(ethylene glycol) monomethyl ether (PEG). The copolymers were obtained via the ATRP of N-isopropylacrylamide (NIPAM) with CuCl/Me6TREN as catalyst and DMF/H2O (v/v = 3:1) mixture as solvent. The resulting polymers were characterized by gel permeation chromatography (GPC) and 1H NMR. These block copolymers show controllable molecular weights and narrow molecular weight distributions (PDI <1.15). Their phase transition temperatures and enthalpy changes in aqueous solution were measured by differential scanning calorimetry (DSC). The results indicate a significant influence of the macromolecular architecture on the phase transition. This is the first study into the effect of molecular architecture on the phase transition using Y-shaped amphiphilic block copolymer composed of PEG and PNIPAM.
Thermoelectric Properties of Y-Doped Mg2Si Prepared by Field-Activated and Pressure-Assisted Reactive Sintering
Authors: Meng Qing Sen , Wang L.Q. , Li B.S. , Ding L.Z. , Chen Shao Ping
Published: September 2009

Reactive sintering of elemental powders was used to form Y-doped Mg2Si (Y: 1000, 2000, 3000ppm) using a field-activated pressure assisted synthesis (FAPAS) method. XRD analysis, and the calculation of lattice constant (a) indicates that 1000ppm is the solid solubility of Y in Mg2Si. Sample doped with 2000ppm Y owns better performances, the absolute value of Seebeck Coefficient increases in the temperature of 288-580K and is higher than that of non-doped Mg2Si, and it got higher electric conductivity and higher power factor, which reaches up to 1.67 times of non-doped Mg2Si at 438K and 2.03 times of that of non-doped Mg2Si at about 408K. Meanwhile, the introduction of Y can decrease thermo-conductivity obviously, proving that the introduction of Y is favorable for both electrical and thermal properties.
Preparation of Amorphous Calcium Phosphate/Triclcium Silicate Composite Powders
Authors: Lin Qing , Li Yan Bao , Lan Xiang Hui , Lu Chun Hua , Xu Zhong Zi
Published: September 2009

The amorphous calcium phosphate (ACP)/tricalcium silicate (Ca3SiO5, C3S) composite powders were synthesized in this paper. The exothermal behavior of C3S determined by isothermal conduction calorimetry indicated that the ACP could be synthesis by chemical precipitation method during the induction period (stage II) of C3S. The composite powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results indicated that nanosized ACP particles deposited on the surface of C3S particles to form core-shell structure at pH=10.5, and the nCa/nP of ACP could be controlled between 1.0 and 1.5. The core-shell structure is stable after sintered at 500 oC for 3 h to remove the β-cyclodextrin (β-CD). As compared with the irregular C3S particles (1~5 μm), the composite powders particles are spherical with a diameter of 40~150 μm. Therefore, to obtain the smaller size of composite powders, it is expected to avoid the aggregate of C3S particles in the aqueous solution by addition of dispersant. As compared with C3S, the composite powders may contribute better injectability, strength and biocompatibility.
Microstructure Evolution of Directionally Solidified Al-25at.%Ni Peritectic Alloy
Authors: Su Yan Qing , Liu Dong Mei , Li Xin Zhong , Luo Liang Shun , Guo Jing Jie , Fu H.Z.
Published: September 2009

Microstructure evolution of peritectic Al-25at.%Ni alloy during directional solidification with pulling velocity ranging from 2 to 500m/s is investigated. The directional solidified alloy is composed of Al3Ni2, Al3Ni phase and eutectic (Al3Ni+Al) phase. When pulling velocity ranges from 2 to 5m/s, Al3Ni phase grows into an integral matrix. Majority of primary Al3Ni2 is consumed by peritecti reaction and transformation behind the peritectic interface with pulling velocity ranging from 2 to 20 m/s. While pulling rate increases, major Al3Ni phase direct solidifies from liquid. With cooling rate increasing, Al3Ni2 phase content firstly decreases and then increases, while the Al3Ni phase content decreases throughout.
The Preparation of Ti-6Al-4V Alloy Rod and Blade by Metal Mold Suction Casting and the Effects of Hydrogen on Them
Authors: Wang Liang , Su Yan Qing , Ye Xi Cong , Luo Liang Shun , Guo Jing Jie , Fu H.Z.
Published: September 2009

In the article this is a new way to prepare Ti-6Al-4V alloy rod and blade by metal mold vacuum suction casting. The effects of hydrogen on the suction casting is also studied. It is found that the alloy melt can be sucked up easily by the mold and has a better fluidity because of H2. Hydrogen can make the electrical current for suction casting decrease sharply compared with the electrical current in Ar. Hydrogen can refine the grain size of the alloy rod and blade. Compared with the unhydrogenated specimen, the peak stress of the hydrogenated specimens increase about 20%, because hydrogen decreases the volume fraction and size of shrinkage porosity.
Morphological Characterization of Chitosan in the Hydroxyapatite/Chitosan Nanocomposites
Authors: Lu Xiao Ying , Wang Xiu Hong , Wang Jian Xin , Qu Shu Xin , Weng Jie
Published: September 2009

The morphological differences of chitosan (CS) in the hydroxyapatite (HA)/CS nanocomposites were investigated in detailed, which were prepared via in situ hydrothermal precipitation. The results show that the obtained nanocomposites have excellent crystallinity and the crystal has excellent ordered structure, which is important to the composites performances in the biomedical application. Moreover, the CS arrangement and crystallinity in the composites greatly depend on the hydrothermal temperature and the pH value of precipitating agent. The temperature ranging from 373 to 413K and pH value of precipitating agent ranging from 12 to 14 were favorable to the crystallization and oriented growth of CS molecules in the composites. The CS crystals with better arrangement are assembled in the order of layer-by-layer in these composites.