bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Corrosion Behaviors of Copper Manganese Aluminum Alloy in Microbiologically Influenced Corrosion
Authors: Lin Jing , Yu Gui Wen , Ma Li
Published: September 2009

Microbiologically Influenced Corrosion behavior of copper manganese aluminum alloy (CMA) were studied in the environment of sulfate-reducing bacteria (SRB). Surface topography of microorganism films were observed by using atomic force microscopy (AFM) and Scanning Electron Microscope (SEM), The result showed that number of SRB were a little, so that microorganism films can’t form in the surface of CAM; Microscopic structure was analyzed in the process corrosion, with increase of exposure time, selective corrosion occurred mainly on containing Al at a high level of β-phase and κ-phase. X-ray Photoelectron Spectroscopy (XPS) showed the main component of corrosion product was Sulphide. The change of Ecorr and corrosion current density in culture medium containing SRB was greater than it in 3.5% NaCl. It showed that the selective corrosion of the copper was accelerated by the metabolism substance. The content of sulfide was increasing with exposure time increasing.
Preparation of Ultra-Fine MgO•Al2O3 Spinel Powder and its Metallurgy Behavior in Medium Carbon Steel
Authors: Li Yang , Zhi Wei Jun , Li Wei Jian , Wang Liang You , Jiang Zhou Hua
Published: September 2009

Micron, sub-micron and nanometer sized MgO•Al2O3 ultra-fine powders were prepared by gel precipitation, solid-phrase synthesis, sol-gel and flame throwing pyrogenation methods. XRD analysis shows that the all of the ultra-fine powder is pure with a single MgO•Al2O3 spinel phase. The size is measured by laser granularity analyzer and the average size is 60, 505 and 1780 nm with quite uniform distribution. MgO•Al2O3 spinel powder with different granularity were sprayed into molten medium carbon steel in MgO crucible and MoSi2 furnace at 1873 K. Quantitative microscopic examination shows that big particle inclusions are reduced and small particle inclusions increased, and the average size is reduced. Data comparison from spraying different size powders shows that spraying MgO•Al2O3 of nanometer tends to cause more small inclusions. The sprayed steel samples were rolled and heat treated for the mechanical properties tests, which shows spraying nanometer MgO•Al2O3 is the best way to improve mechanical property.
Study onCorrosion Behaviour of AISI 316L Stainless Steel Treated with Air Cold Plasma
Authors: Wang Qi , Wang Hong Ren , Gao Cong Jie , Liu Feng
Published: September 2009

Pitting resistance of air cold plasma-oxidation 316L stainless steel was evaluated by exposing the specimens into a ferric chloride solution. The results indicate that the pitting resistance of plasma-oxidized specimens improved obviously. Potentiodynamic polarization curves were measured to study its corrosion behavior. The corrosion mechanism was also interpreted by electrochemical impedance spectroscopy (EIS) and Auger electron spectroscopy (AES).The results reveal that the oxide layer formed by the plasma treatment is much thicker than that without treatment and is double-deck structure, which leads to the change of EIS characteristic of sample surface.
Inhibition Microbial Adherence of Superhydrophobic Surface on Aluminum in Seawater
Authors: Liu Tong , Yin Yan Sheng , Li Lan
Published: September 2009

A superhydrophobic film with an anti-corrosive propertyhas been fabricated on the anodized aluminium foil by myristic acid (CH3(CH2)12COOH, mya) chemically adsorbed. The surface structure and composition were then characterized by means of scanning electron microscopy (SEM) The static contact angle (CA) for seawater is measured to be larger than 150°. The fluoroscope and scanning electron microscopy (SEM) show the samples with the superhydrophobic film which is immersed into nature seawater for 24h significantly decrease adhesion of microorganisms. The appearance of the microorganisms is characterized by transmission electron microscopy (TEM). The study suggests the superhydrophobic film dose not only decrease the corrosion currents densities (icorr), but also microbially influencing corrosion acceleration inhibition (MICI) due to preventing colonization of microorganisms. A hypothesis is indicated that aluminums whit the superhydrophobic film could be used as a kind of excellent marine materials.
Notched Tensile Fracture of Ti-6Al-6V-2Sn Welds at Elevated Temperature
Authors: Tsay Lv Wen , Hsu C.L.
Published: September 2009

The notched tensile tests of Ti-6Al-6V-2Sn laser welds with distinct post-weld heat treatments (PWHTs) were carried out at 150, 300, and 450oC and the results were also compared with the mill-annealed base metal (BM). The BM specimen had the highest notched tensile strength (NTS) among the specimens being tested at room temperature but became the lowest at 450oC. At/above 150oC, all welds showed a decrease in NTS with increasing temperature. The cracks tended to grow along the α / β interface in the BM specimen. The formation of premature fine pores at the grain boundary in the weld with PWHT at 704oC accounted for the intergranular dimple fracture of the specimen. The fracture appearance of the as-welded (AW) and the 482oC-aged (W-482) welds comprised of mainly transgranular dimple and increased the extent of grain boundary shear at elevated temperature.
Coupled Numerical Analysis of the Anti-Crack Mechanism for Open-Graded Large Stone Asphalt Mixes
Authors: Guo Hong Bing , Chen Shuan Fa
Published: September 2009

The reflective cracking in asphalt surface is a technical problem that exists in the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure, how to control its emergence and development is still a major problem for road engineering. At present, researches on the anti-cracking performance for Open-graded Large Stone asphalt Mix (OLSM) in China almost remain in the test road observations, very few study the mechanism of its anti-cracking from the mechanical point. Aiming at this problem, a method of using OLSM as the cracking relief layer is proposed, large mineral aggregate, low asphalt content and a great deal of void in OLSM can dissipate or absorb stress and strain around the crack. The 3-D finite element method is used to analyze the crack-alleviating layer of ordinary asphalt concrete and OLSM, and the large-scale commercial finite element software of ABAQUS is used to do numerical simulation analysis for the lean concrete base asphalt pavement structure with OLSM, the analysis result indicates that temperature-load coupling stress of OLSM are less than that of ordinary asphalt concrete. Depending on the test road on an expressway, research on the anti-crack mechanism of OLSM has been conducted. The investigation of the test road and the result of the theoretical calculation indicate that OLSM can prevent lean concrete base asphalt pavement from the reflective cracking effectively, OLSM has good anti-cracking performance, it is an effective material to alleviate the reflective cracking. As the crack-alleviating layer, OLSM can significantly enhance the anti-cracking ability of the semi-rigid base asphalt pavement structure and the rigid base asphalt pavement structure.
Finite Element Method Simulation of 35# Steel Cathodic Protection Models in the Seawater
Authors: Sun Hu Yuan , Wang Wei , Sun Li Juan
Published: September 2009

Physical models of cathodic protection (CP) for copper protected by 35# steel and for 35# steel protected by aluminum sacrificial anode respectively in seawater were built in this study. Weak form of Laplace equation was deduced to make finite element method (FEM) numerical calculation conveniently. Then, potential distribution of each physical model was computed by FEM following with measured experiments for validation. Typical FEM simulated data along X-axis and Y-axis of physical models agree well with measured experimental data. For 35# steel protected by aluminum sacrificial anode models, normal cathodic protection, over-protected (OP) and under-protected (UP) models were built, respectively. The results demonstrated that it should be feasible of CP for copper by 35# steel and for 35# steel by aluminum sacrificial anode respectively, and FEM could afford well forecast for CP design in engineering.
The Effect of Creep on Morphology Change of Surface Groove on Fecralloy in TBCs during Thermal Oxidation Cycles
Authors: Huang Xia , Ding Jun , Kang K.J.
Published: September 2009

In this work, the effects of creep behaviors for constituent materials in thermal barrier coatings (TBCs) on the morphology change occurring near the surface groove are investigated upon twenty-four purely thermal cycles using the finite element method. The formation of thermally grown oxide (TGO) in lateral and thickness directions at high temperature are simulated by means of material property change based on in-house measured material properties such as yield strength and TGO final thickness. The result shows that under the purely thermal cycles the creep in constituent materials significantly enhances the morphology change near the grooves. It is also found that creep in only substrate predominates at high temperature while creep only in TGO plays a less important role in the morphology change due to its relatively slower creep behavior compared to Fecralloy substrate.
Numerical Investigation on the Effect of Copper Filler Thickness on the Brazed Residual Stress
Authors: Xie Qiao Yun , Ling Xiang
Published: September 2009

In this study, the residual stress in copper base brazed stainless steel plate-fin structure was investigated through thermo-mechanical coupled finite element analysis (FEA) models. The results show that the maximum residual tensile stress occurs in the brazed joint next to the plate side. In addition, the dependence of residual stress distribution on filler thickness was also analyzed. The detailed stress distribution would provide some constructive instructions in the practical brazing procedure.
Numerical Simulation of Thermal Cycle of In-Service Welding on X70 Steel Gas Pipeline
Authors: Chen Yu Hua , Wang Yong , Wang Zheng Fang
Published: September 2009

In-service welding is a kind of important method to ensure the integrality of oil gas pipeline and the thermal cycle of which is significant for repairing. Used SYSWELD to establish model and simulate thermal cycle of in-service welding on X70 steel gas pipeline, compared thermal cycles of in-service welding and air-cooling welding, studied the influence of gas pressure and flow rate on thermal cycle. The result shows that peak temperature of the coarse grain in heat affected zone (CGHAZ) of in-service welding is similar to air cooling welding, but the cooling time of t8/5, t8/3 and t8/1 decreases at certain degree. Peak temperature of CGHAZ of in-service welding doesn’t vary match with gas pressure and flow rate either. t8/5, t8/3 and t8/1 decrease when gas pressure increases. t8/5 varies with the gas pressure linearly. When the pressure is less than 4MPa, t8/3 and t8/1 decrease rapidly while gas pressure increases. When the pressure is more than 4MPa, t8/3 and t8/1 decrease slowly while gas pressure increases. t8/5, t8/3 and t8/1 decrease when the flow rate increases. When gas flow rate is less than 10m/s, t8/5, t8/3 and t8/1 decrease rapidly while flow rate increases. When gas flow rate is more than 10m/s, t8/5, t8/3 and t8/1 decrease slowly while flow rate increases.
Calculation and Analysis of Valence Electron Structures of the Precipitated Phases in Al-Cu Alloy
Authors: Liu Wei Dong , Qu Hua
Published: September 2009

According to the empirical electron theory of solids and molecules, the valence electron structures of GP zone, θ″, θ′ and θ phases in Al-Cu alloys are calculated out. The results show that the number of covalent electron pairs on the strongest bond A of GP zone is greater than that of of the  matrix, i.e., the obstruction of in GP zone for dislocation movement is stronger than that of in the  matrix. Only based on the bond strength of composition atoms, it can be found, , , and  phases have strengthening effects for Al-Cu alloys. The strengthening effect of  is the strongest, and  is weaker, and  is the weakest. Compared with, the bond strength of  and  is weaker than that of . From the value of nA, it is easy to reconstruct the bonds of GP zone, , and , but is difficult to reconstruct the bonds of .
Three-Dimensional Numerical Simulation of Residual Stresses by Shot-Peening
Authors: Zhang Hong Wei , Zhang Yi Du , Wu Qiong
Published: September 2009

Shot peening is a complex cold working process used to improve the fatigue life of metallic parts. This investigation is devoted to the modeling and simulation of the residual stress field resulting from the shot peening process, in which the finite element method was employed using a rate sensitive material. The history of energies during explicit dynamic analysis was discussed and the solution time for explicit analysis was analyzed. For the single shot impact model, the effect of shot velocity, shot size, incident angle was studied. In addition, the effect of repeated impacts on the residual stress within the target plate was studied. Furthermore, the multiple shot impacts of shot peening process were accomplished and the effect of peening coverage was investigated based on different shot models.
Effect of Li on Al-Si Alloys Structure and Properties
Authors: Zhao Zhong Kui , Qiao Zhen , Li Chang Long , Sun Qing Zhou , Zhang Pu Qing , Wang Gui Qing
Published: September 2009

Al-12Si alloys containing1%, 2% and 3% lithium were prepared. The alloys were melted by a vacuum induction furnace. The microstructure was observed by optical microscopy, tensile test was performed at a rate of 1mm•s-1. Hardness was determined by a Vicker’s hardness machine. Adding 1%Li to the of Al-12Si alloy, the alloy is modified and its structure is eutectic. When Li content is 2% or 3%, the structure is hyper-eutectic, and proeutectic Si-phases are present. The Al-12Si-1Li alloy has a tensile strength of 190MPa and an elongation of 1%. With the increment of lithium, the strength and elongation of Al-12Si containing Li alloys gradually decreases, because of the presence of proeutectic Si-phases. The alloys exhibits hardening behaviors when ageing at 200°C, and the hardness decreases to a value with the prolongation of the ageing time.
Quantum Chemical Calculation of Maleic Anhydride Ring-Opening Reaction
Authors: Zhang Ming , Huang Zhi Xiong , Qin Yan
Published: September 2009

The reaction of maleic anhydride ring-opening was calculated by Gaussian03. The Density Function Theory (DFT) method were employed to study the geometries of maleic anhydride and ethanol on the base of B3LYP/6-31G in the paper. The transitional states(Ts1,Ts2) of maleic anhydride ring-opening reaction were found by TS method and were proved by IRC calculation. The results showed that from the reactant to product, the energy reduced about 129.25337kJ/mol,The computation results showed that the reaction was exothermic and matched up well with experiment.
Nowadays the MAH multipolymers were studied extensively.Because of C=C double bond has double substitutions and the great Spatial steric hindrance, MAH was always regarded as representative that couldn’t carry out homopolymerization[1,2]. Much attention has been paid to MAH polymerization(Homopolymerization[4] and Copolymerization[5-15])gradually Long and his colleagues[3] published papers on MAH homopolymerization in 1963. The related reports have been increased since MAH multipolymer was found to possess anti-tumor and biological activity[16].
According to the polymerization mechanism，epoxide ring-opening esterification were divided into three kinds: cationic polymerization, anionic polymerization and coordination polymerization.The saturated polyesters were prepared through maleic anhydride and alkene oxide reaction, generally using anionic polymerization initiated by hydroxyl compound such as alcohol, water and carboxylic acid. maleic anhydride ring-opening reaction initiated by alcohol(Eq. 1) was discussed in this paper.
Dynamic Models for Magnetorheological Dampers and its Feedback Linearization
Authors: Zhang Cheng , Wang Lin Xiang
Published: September 2009

In the current paper, the hysteretic dynamics of magnetorheological dampers is modeled by a differential model. The differential model is constructed on the basis of a phenomenological phase transition theory. The model is expressed as a second order nonlinear ordinary differential equation with bifurcations embedded in. Due to the differential nature of the model, the hysteretic dynamics of the MR dampers can be linearized and controlled by introducing a feedback linearization strategy.
Experiment Research on Purifying Metallurgical Grade Silicon and Crystal Growth in Directional Solidification
Authors: Mei Xiang Yang , Ma Wen Hui , Wei Kui Xian , Dai Yong Nian
Published: September 2009

The main raw material of solar energy is multi-crystalline silicon. Directional solidification technique is one important technological process of metallurgy purification technology for multi-crystalline silicon. It can purify metallurgical grade silicon by removing metal impurities and control crystal growth at the same time. In experiment, metallurgical grade silicon by acid leaching pre-treatment, was purified by our self-assembled directional solidification furnace. The sample was analyzed by electron-prode micro analysis (EPMA). According to the results, the removal efficiency of Fe and Al is 96.3% and 96.7%, respectively. The removing mechanism of metal impurities and the difference between theory value and experiment value were also discussed. The segregation effect in directional solidification is the reason of removing Fe, but analgesic effects of the segregation effect combined with vacuum volatilization are that of removing Al. When the silicon ingot was cooled down, lengthways section of silicon ingot was cut and etched, crystal growth was studied. The results indicate that columnar crystal growth shows diverging tendency from the bottom to the top of silicon ingots, and solidification interface shape is convex. The reasons may be the nucleation of new crystals on crucible sidewall is very serious and the pulling rate is too high.
Polyethylene Rubber Composite Target Resistance to Jet Penetration
Authors: Zu Xu Dong , Huang Zheng Xiang , Xiao Qiang Qiang , Xia Ming
Published: September 2009

A “sandwich-style” composite target with a 45 steel surface plate, polyethylene rubber sandwich plate, and 45 steel back plate is studied for jet penetration resistance. The effects of varying layer thickness are analyzed using AUTODYN software and energy-thickness (E-T) curves in Matlab. The influence of the scale effect on each of these composite layers is analyzed. Results from the E-T curves confirm that varying the thickness of the 45 steel back plate has an obvious influence on jet penetration resistance. Moreover, varying the thickness of the front plate and the sandwich plate has a large effect on jet fracture after penetration of the composite target. Experiments prove that the results of the simulation are correct, and that the scale effect is present for these composite targets under jet penetration.
A Study on the Advanced Surface Characteristic of Yttria (Y2O3) Ceramic by Using Optimal Design of Process
Authors: Cha Ji Wan , Lee Eun Sang
Published: September 2009

Since a fine ceramic is possessed of creditable physical and chemical material properties: high thermal resistance, chemical inertness and frictional wear resistance, its applications have been increasing in various industrial fields. Yttria(Y2O3) ceramic, which is formed of cubic crystal structure, has been considered as a light-transmitting material for an optical application and suitable buffer layer in the electronic industry. And its other applications have been increasing recently. For the effective applications of Yttria ceramic, it needs to improve a surface characteristic such as the waviness and surface roughness. The lapping process with in-process electrolytic dressing(IED) method has been performed in the surface machining of high hard-brittle material. IED method is able to overcome the surface machining defects caused by worn grains and unstable chip discharge during conventional lapping process. However, the machining control should be carefully conducted and investigated about each material because its material properties are different each other and exceedingly sensitive. Taguchi method, called robust design, is a useful method for engineering productivity elevation. It is able to search a powerful factor, which influences optimal process design, in accordance with considering noise factors reduction. When diverse factors influence a result according to complex actions each other, it needs to search optimal condition of factors. Response surface design has been widely used in various industrial fields. It helps to solve process design problems in accordance with robust design of process condition.
Buckling Response of Metallic Foam Composite Sandwich Panels Subjected to Edgewise Compression
Authors: Wang Xin Zhu , Wu Lin Zhi , Wang Shi Xun
Published: September 2009

In present work, the critical buckling load of metallic foam composite sandwich panels is calculated by experimental, finite element methods (FEM) and theoretical analysis. The experimentally investigated is based on an edgewise compression test program to examine buckling failure and compressive properties. The metallic foam sandwich panels under edgewise compression tend to collapse in overall buckling mode. The most important factor that determines the overall buckling load of a sandwich panel under edgewise compression is the shear properties the metallic foam core. The sandwich beam theory and the FE model are developed for prediction of the buckling load of metallic foam sandwich structure. In despite of some differences existed among experimental data, FE and theoretical results, considering the existence of initial defects in sandwich structures which can’t be calculated in FE model and theory anlysis, the differences are in the reasonable range. The FE program developed in this paper can effectively be used to simulation of edgewise compression response for metallic foam composite sandwich structures. Theoretical and FE model results are in agreement with experimental result.
3D Fem Study of Fluid Flow in the Mould for Billet Continuous Casting
Authors: Chen Wei , Wang Bao Xiang , Zhang Yu Zhu , Ma Jin Hong , Yuan Su Juan
Published: September 2009

In this paper, a three-dimensional finite element model is developed to simulate and analyze the turbulent flow in the mould of billet continuous casting. The result shows that if the SEN is used in the continuous casting process, there exists a symmetrical stronger vortex in the middle of the mould and a weaker vortex above the nozzle. The casting speed, the depth and diameter of SEN all have significant effect on the fluid flow field and the turbulent kinetic energy on the meniscus, and then have effect on the billet quality. At the given conditions, the optimum set of parameters is: the casting speed 0.035 , the depth of the SEN 0.1 , the diameter of the SEN 0.025 . Online verifying of this model has been developed, which can be proved that it is very useful to control the steel quality and improve the productivity.
Modeling and Testing for Small-Scale Time Delay Device Based on Magnetorheological Fluid
Authors: Sui Li , Shi Geng Chen , An Kun , Wei Bao Jian
Published: September 2009

Because of magnetorheological (MR) dampers’ mechanical simplicity, high dynamic range, low power requirements, large force capacity and robustness, they are the most promising devices for structural vibration control. But this paper uses MR dampers’ damp characteristics to complete a function of short time delay, and the damper’s volume is smaller than the other dampers that have been applied for commercial uses. This paper discusses two types of structures for time delay, gap structure time delay device and holes structure time delay device. In order to estimate the two kinds of devices’ delay time, mathematical modeling and experimental testing are built in this paper. From the test results, we know that holes structure does not always implement theoretical delay time, but the gap structure can complete the time delay function satisfactory. For judging whether the time delay device can work normally under different circumstance, the time delay device with gap structure is tested in a change temperature field from -40 °C to 55 °C.
Molecular Simulation of the Interfacial Properties of an Epoxy Composite Reinforced Using a Carbon Nanotube/Carbon Fiber Hybrid
Authors: Zhang Fu Hua , He Xiao Dong , Dong Li Hua , Yin Yan Sheng
Published: September 2009

Molecular simulations of the interfacial properties of (1) a composite with an epoxy(EP) matrix and a carbon nanotube(CNT)/carbon fiber(CF) multi-scale reinforcement and (2) a traditional CF/EP composite were performed employing Materials Studio 4.0 software. Results indicate that the interfacial atom concentration of material 1 is higher that that of material 2 by interfacial molecular structure analysis, and there are many benzene rings in both material 1 and material 2 which are parallel to the crystal layers of CF. The contact layer thickness of material 1 and material 2 is 0.25 and 0.10 nm, respectively. The concentration distribution calculation of EP molecules in the interface shows that the most concentrated part of EP in material 2 appears in the carry-forward area of the contact layer, while it is more close to the contact layer in material 1.
Modeling of Dynamic Characteristics of Ionic Polymer-Metal Composite Beam near Resonant Frequencies
Authors: Zhang Lei , Yang Yao Wen
Published: September 2009

In this paper, the dynamic characteristic of an ionic polymer-metal composite (IPMC) cantilevered beam near resonant frequencies is investigated. A dynamic model is formulated on the basis of beam vibration, charge distribution and charge interactions. Experimental tests are conducted with an IPMC cantilevered beam actuated in frequency domain. Comparison with experimental results shows that the theoretical model is able to predict the dynamic responses of IPMC near resonant frequencies.
Recent Development of Molecular Simulation Based on GPU in Material Science
Authors: Yu Kuan , Zhu Bo
Published: September 2009

Molecular simulation can provide mechanism insights into how material behaviour related to molecular properties and microscopic details of the arrangement of many molecules. With the development of Graphics Processing Unit (GPU), scientists have realized general purpose molecular simulations on GPU and the Common Unified Device Architecture (CUDA) environment. In this paper, we provided a brief overview of molecular simulation and CUDA, introduced the recent achievements in molecular simulation based on GPU in material science, mainly about Monte Carlo method and Molecular Dynamics. The recent research achievements have shown that GPUs can provide unprecedented computational power for scientific applications. With optimized algorithms and program codes, a single GPU can provide a performance equivalent to that of a distributed computer cluster. So, study of molecular simulations based on GPU will accelerate the development of material science in the future.
Modeling and Simulations of Pd/n-ZnO Schottky Diode and its Comparison with Measurements
Authors: Faraz S , Noor Haida , Asghar M. , Willander Magnus , Wahab Qamar-ul
Published: September 2009

Modeling of Pd/ZnO Schottky diode has been performed together with a set of simulations to investigate its behavior in current-voltage characteristics. The diode was first fabricated and then the simulations were performed to match the IV curves to investigate the possible defects and their states in the bandgap. The doping concentration measured by capacitance-voltage is 3.4 x 1017 cm-3. The Schottky diode is simulated at room temperature and the effective barrier height is determined from current voltage characteristics both by measurements and simulations and it was found to be 0.68eV. The ideality factor obtained from simulated results is 1.06-2.04 which indicates that the transport mechanism is thermionic. It was found that the recombination current in the depletion region is responsible for deviation of experimental values from the ideal thermionic model deployed by the simulator.
Study on Nanomechanical Properties of Dragonfly Wing
Authors: Chang Ching Hsin , Ting Ku En , Chen Kuen Tsan
Published: September 2009

The flight mechanics of dragonflies including hovering and taking off backwards, flight sideways and vertical directions has been attentions in Bionics. The dragonfly wing consists of the networks of various veins and membranes to make the structural properties complicated. In the past investigations, surface characteristics of dragonfly wing were measured by nanoindentation test. Thus the aim of this study will comprehensively concern the nanomechanical properties of veins, membrane and pterostigma of the wing of the dragonfly with nanoindentation. In the mean time, the modulus and hardness of the wing of the dragonfly’s composites including lengthwise vein, transverse vein, membrane and pterostigma are measured. The value of modulus of lengthwise vein is greater than the other structures. The value of modulus of transverse vein is the smallest due to its soft behavior. Its hardness is also smaller than others.
Electronic Structure of Bimetallic FemAln (m+n=6) Clusters
Authors: Chen Shou Gang , Sun Wei Wei , Yu Shuai Qin , Yin Xun Jun , Yin Yan Sheng
Published: September 2009

Theoretical study on the electronic structure of small FemAln(m+n=6) clusters has been carried out at the BPW91 level, and the electronic structures, binding energy and vertical ionization potential of clusters were evaluated. For the stable clusters, the iron atoms gather together and form a maximum of Fe-Fe bonds, and the aluminum atoms locate around Fe core with a maximum of Fe-Al bonds. The binding energy and vertical ionization potential show that the Fe5Al, Fe4Al2 and Fe3Al3 clusters have higher stability, which results provide insight into the properties of iron-aluminides can be obtained from a finite size cluster model.
In Air Synthesis of Bi2S3 and PbS Microcrystals by Thermolysis of Single-Source Precursors
Authors: Du Zhen Ni , Zhang Yong Cai
Published: September 2009

Without the protection of inert gases or vacuum environment, rod-like Bi2S3 and cubic-shaped PbS microcrystals were synthesized directly via pyrolyzing corresponding metal diethyldithiocarbamates in air at 300 °C for 3 h. The products have been characterized by X-ray diffraction and scanning electron microscope, and their possible formation mechanisms were also tentatively proposed. Furthermore, control experiments with multiple-source precursors revealed that our single-source precursors played an important role in preparing phase-pure Bi2S3 and PbS.
Convective Heat Transfer Steady Thermal Stress in a Ceramic/FGM/Metal Composite EFBC Plate with Temperature-Dependent Material Properties
Authors: Xu Yang Jian , Tu Dai Hui
Published: September 2009

A NFE model is constructed to analyze the convective heat transfer steady thermal stress in a ceramic/FGM/metal composite EFBC plate with temperature-dependent material properties. Based on thermoelasticity theory, we derive the NFE basic equation of heat conduction of the plate. We present a Sinpson method for the solution of steady thermal stress formulas of the composite plate. Using FORTRAN language we design the calculation software. From numerical calculation, when , T0=300K, Ta=500K and Tb=1 650K, the stress distributions in the plate were obtained. The results are as follows. With the increase of the FGM gradient layer thickness, the stress distribution is more reasonable, and the largest tensile stress of the EFBC composite plate reduces by 59.6%. With the increase of M, the stress change increases obviously in metal and ceramic layers, and the thermal compressive stress on the ceramic surface reduces by 78.1%. With the increase of porosity, the change of stress at the bonding interfaces increases, and the thermal compressive stress on the surface of ceramics reaches the maximum, and the thermal tensile stress on the surface of metal reaches the maximum too. Compared with , when , the tensile stress on the metal surface reduces by 91.3%, and the maximum compressive stress on the surface of ceramics increases 4.55 times. Compared with the nongraded two-layered ceramic/metal composite plate, the thermal stress of ceramic/FGM/metal composite EFBC plate is very gentle, and the maximum tensile stress reduces by 62.94%. When we consider the temperature-dependent material properties, the stress in graded three-layered composite plate becomes small obviously, and the maximum tensile stress in the plate reduces by 36.74%, and the maximum compressive stress on the ceramic surface reduces by 31.4%. The model can effectively analyze the thermal stresses and effect factors in a ZrO2/FGM/Ti-6Al-4V composite plate. The results provide the foundations of theoretical calculation for the design and application of the composite plate.
Low-Temperature Preparation of Biomorphic TiC/C Ceramic in Molten Salt Media
Authors: Zhu Hong Xi , Ding Jun , Deng Cheng Ji , Zhang Shao Wei
Published: September 2009

In the present work, biomorphic TiC/C ceramic with a woodlike structure was synthesized from wood template. The TiC coatings were formed on the surface of C-wood-template in a reaction medium consisting of Ti powder in a mixture of molten LiCl-KCl salts under an argon atmosphere. The structure and biomorph of the TiC/C ceramic were characterized by XRD, TG-DSC, SEM and EDX analyses. The results indicated that Ti powder had reacted with carbon in the cellular wall to form TiC coatings. The resulting biomorphic TiC/C ceramic retained well the structure of the original biomorph of the wood.
Fracture Test and Numerical Analysis of Structural Steel Notched Plates Based on Generalized Strength Model
Authors: Wang Wan Zhen , Su Ren Quan , Wang Xin Tang , Feng Xiang
Published: September 2009

To study rupture mechanism of structural steel, fracture experiments were tested on 12 notched plates with different thickness. The results of experiments indicated that the first crack initiated at the notched edge and expanded rapidly along the width of the plates after running through the thickness. Finally, the specimens fractured at the critical section, the fracture ductility decreased with the thickness. By numerically simulating the fracture stress field of the notched plates at initial cracking based on generalized yield model, the applicability and accuracy of the suggested fracture criterion were comparatively verified.
Microstructure and Tensile Property of Zn-Al Alloy Reinforced with Titanium Produced by Electrolysis
Authors: Yan Shu Qing , Xie Jing Pei , Wang Wen Yan , Li Ji Wen
Published: September 2009

In this study, some low-titanium aluminum alloys produced by electrolysis were prepared and the effect of various titanium contents on microstructure and tensile property of Zn-Al alloy was investigated. The test results showed that addition of titanium by electrolysis is an effective way to refine the grain size of Zn-Al alloy. As the titanium content is 0.04 wt%, the grain size becomes to be a minimum value and the tensile property of the alloy reaches to the maximum. Electrolysis showed that titanium atoms are to be some inherent particles in low-titanium aluminum alloy. These titanium atoms enter into the aluminum melt liquid and spread to the whole melt rapidly under stirring action of electromagnetic field of the electric current. The heterogeneous phase nuclei are high melting TiC and TiAl3 particles formed from in-situ precipitating trace C and Ti during cooling process. These in-situ precipitating heterogeneous nucleation sites with small dimension, high dispersity, cleaning interface and fine soakage with melt, have better capacity of heterogeneous nucleation than of exotic particles. It may inhibit grain growth faster and more effective in pinning dislocations, grain boundaries or sub-boundaries.
Semi-Solid Thixoforming Simulation of ZL201 Alloy Parts via AnyCasting
Authors: Jing Liu , Tian Liang , Ping Wang
Published: September 2009

The software AnyCasting was used to simulate the thixotropic die-casting process of semi-solid ZL 201 alloy slurry to form the parts of particular shape, especially how the size of the in-gate of die and injection speed affect the process. The results showed that the die cavity can be filled well with the semi-solid slurry in form of laminar flow under conditions that the temperature of the semi-solid slurry is 640±5°C and that of die 200～240°C, thickness of the in-gate is 11mm and, more important, the injection speed is changed from 0.1 m/s to 1.0m/s when 60% of die cavity has been filled.
Experimental and Thermal Analysis of Sheet Molding Compound with Magnesium Oxychloride Crystal Salt Using as Flame Retardant
Authors: Li Jian , Huang Zhi Xiong
Published: September 2009

A kind of magnesium oxychloride crystal salt with high content of 5•1•8 crystalline phase was prepared in this research. And detailed experimental studies were carried out to determine the effect of magnesium oxychloride crystal salt on the flame retardance and thermal properties of compression molded SMC parts. Results showed that the comprehensive properties of SMC were optimum when the weight content of magnesium oxychloride crystal salt was 40%, and the oxygen index was 35.6 and the inflaming level was V-0 according to UL-94. The thermal decomposition process of pure magnesium oxychloride crystal salt was carried out in the following three steps: releasing crystal water, then HCl secondly and finally structural water, the residua was magnesia. The apparent activation energy of reaction in each step was 124.31kJ/mol, 111.50kJ /mol, 113.40 kJ /mol and the reaction order was 2.11, 2.04, and 0.98 respectively.
Far-Field Solution of Circular Lining and Linear Crack by SH-Wave
Authors: Li Hong Liang , Zhang Rui
Published: September 2009

Circular lining is used widely in structure design. In this paper, the method of Green’s function is used to investigate the problem of far field solution of circular lining and linear crack impacted by incident SH-wave. Firstly, a Green’s function is constructed, which is a fundamental solution of displacement field for an elastic space possessing a circular lining while bearing out-of-plane harmonic line source force at any point; Secondly, in terms of the solution of SH-wave’s scattering by an elastic space with circular lining, anti-plane stresses which are the same in quantity but opposite in direction to those mentioned before, are loaded at the region where the linear crack is in existent actually; Finally, the expressions of displacement and stress are given when the circular lining and linear crack exist at the same time. Then, the far field of scattered wave is studied. The results can be applied in the study of fracture, and undamaged frame crack detection.
PVDF Films with Superhydrophobic Surface Fabricated by Plasma-Enhanced Chemical Vapor Deposition
Authors: Zhang Zhi Qiu , Yang Wen Fang , Gu Zhen Ya , Huo Rui Ting
Published: September 2009

Lotus effect is well-known to be governed by chemical properties and nanotextures of the surfaces. In this paper, a method with two-steps treatment technology was applied to develop the superhydrophobic polyvinylidene fruoride(PVDF) membrane with the property of anti-contamination and self-cleaning. First, the PVDF membrane was treated by oxygen plasma so as to get the reactive groups. Second, this film was deposited by perfluoroalkylethyl acrylate precursor/Ar gas via plasma-enhanced chemical vapor deposition (PECVD). The modified film surface exhibited ultra water-repellent ability, showing that the water contact angles was larger than 150 °and the dynamic contact angles was usually lower than 5°.
Coupled Deflection Analysis of SMA Fiber Hybrid Composite Active Blade
Authors: Ren Yong Sheng , Yang Shu Lian , Liu Ting Riu , Wang Xiao Hui
Published: September 2009

The constitutive equations relating cross-sectional loads(forces and moments)to cross-sectional displacements(stretching, bending, twisting) of thin-walled laminated beams with integral shape memory alloy (SMA)active fibers was presented. The variational asymptotic method was used to formulate the force- deformation relationships equations, accounting for the presence of active SMA fibers distributed along the cross-section of the beam. The constitutive relationships for evaluation of the properties of a hybrid SMA composite ply were obtained following the rule of mixtures. The analytical expressions of the actuation components for the active beam were derived based on Tanaka’s constitutive equation and Lin’s linear phase transformation kinetics for SMA fiber. The general form of constitutive relation was applied to the case of stretching-twist coupling, corresponding to Circumferentially Uniform Stiffness (CUS). The present analysis extended the previous work done for modeling generic passive thin-walled laminated beams. Numerical results shown that significant stretching and twisting deflection occur during the phase transformation due to SMA actuation. The effects of temperature on structural response behavior during phase transformation from martensite to austenite are significant. The effects of the volume fraction of the SMA fiber, the martensitic residual strain and ply angle were also addressed
Laser Surface Alloying of NiCr-Cr3C2 and C-B-W-Cr Powders on Nodular Cast Iron Rolls
Authors: Sun Gui Fang , Liu Chang Sheng , Liang Jing , Zhou Jun Hua , Tao Xing Qi
Published: September 2009

The laser surface alloying(LSA) technique was firstly used to form wear resistant layers on nodular cast iron rolls with two different powders, A: NiCr-Cr3C2 and B: C-B-W-Cr. The microstructure, element distribution and phases of the layers were investigated. Results indicate that the alloying layers had pores and cracks, as well as a metallurgical bonding with the substrates. For layers with powder A, as the thickness of the pre-layers decreased, the numbers of pores and cracks of the LSA layers decreased but the thicknesses of them were close. Phases were barely influenced by the thickness of the pre-layer, while the content of them were affected. For layers with powder B, as the laser specific energy increased, the numbers of pores and cracks in the LSA layers decreased and the thicknesses of them increased. The microstructure in the layers with different powders was different.
Microstructures and Wear-Resistant Properties of In Situ WCp/W Wire Hybrid Reinforced Iron Matrix Composites via Electromagnetic Field
Authors: Niu Li Bin , Xu Yun Hua , Wu Hong
Published: September 2009

In the paper, tungsten carbide (WC) particles can be in-situ synthesized by applying electromagnetic field to the system consisting of tungsten wires and gray cast iron melt at 1573 K. The microstructures and wear-resistant properties of composites reinforced by both WC particles and the residual tungsten wires were investigated by XRD, SEM, EDS, micro-hardness and pin-on-disc wear measurements. The results show that, with enhancing frequencies of electromagnetic field from 0 to 5 KHz, the amounts of in-situ WC particles increased and of the residual tungsten wires gradually decreased until tungsten wires completely reacted. Due to the higher hardness of in-situ WCp(2100-2231HV0.1) and the strong interfacial bonding, the composites displayed an excellent wear-resistant properties. When the frequency was 5 kHz, the wear loss for the composite fabricated was optimal and 2.69 times lower than that of reference samples.
Synthesis and Stability of Cubic Silicon Nitride
Authors: Yao Huai , Xu Qiao Yu , Tang Jing You
Published: September 2009

Experiments using a planar metal disc flyer driven by explosives and a cylindrical chamber was designed to synthesize cubic silicon nitride with the mixtures of α-Si3N4 and copper powders as starting materials. The ratio of transformation from α-Si3N4 to γ-Si3N4 approached to 80% percent at 45 GPa pressures and 4000K temperatures. The purity of γ-Si3N4 reached 100% after the synthesized samples were treated with hydrofluoric acid at 440K for 9-10h. High pressure sintering was carried out with a DS6×800A link-type cubic anvil apparatus at a pressure of 5.7GPa and calculated temperature of 1370-1670K over the course of 15 minutes. The result showed that γ-Si3N4 was completely transformed into β-Si3N4 at 5.7GPa, 1420-1670k and was partly transformed into β-Si3N4 at 5.7 GPa, 1370k. Micro-analysis indicated that the typical microstructure of sintered Si3N4 was elongated β-Si3N4 rod crystals in disordered orientation, the highest relative density of the sintered samples was 99.06% and Vickers hardness of them was 21.15GPa.
Synthesis and Electrochemical Behavior of Two Microporous Polyoxomolybdates
Authors: Bao Qi , Zhang Shu Fang , Zhang Dun
Published: September 2009

Two new microporous polyoxomolybdates of (NH4)2[γ-Mo8O26] (Compound I) and (NH4)2[Mo4O13] (Compound II) were synthesized hydrothermally and characterized by elemental analysis, infra-red, TG analysis and single-crystal X-ray diffraction. In the synthesis process, we found that both organic template and transition metal salt play crucial roles in the formation of crystals. Cyclic voltammetry was used to study their electrochemical properties. The results reveal that the two compounds possess electrochemical activity in 0.2M H2SO4+Na2SO4 ( pH=1 ) solution and three multi-electron transferred redox reaction (I-I´, II-II´ and III-III´) processes were obtained. The first two redox reactions (I-I´, II-II´) are reversible reaction processes but another one (III-III´) is not. The electrochemical properties of the two compounds indicate their great potential applications in electroanalysis and electrocatalysis.
Moderation of Entrance Pressure Drop and Extrudate Swelling of Wood Fiber/Polypropylene Composites Melt in Rotating-Die Extrusion Process
Authors: Intawong Naret , Kantala Chatchawan , Lotaisong Watit , Sombatsompop Narongrit
Published: September 2009

A novel rotating-die system was proposed to moderate the elastic swelling for molten polypropylene (PP) and wood/polypropylene (WPP) composite. The results suggested that the neat PP and WPP melts followed the psuedoplastic non-Newtonian pattern. The rotation of the die could moderate the extrusion load and entrance pressure drop. The die rotation effect appeared to be very pronounced for the PP with high wood contents and high extrusion rates. The decreases in extrusion load and entrance pressure drop were related with reductions of melt viscosity due to shear heating effect. The results practically implied that use of the rotating die system could increase the productivity in the extrusion process. In terms of elastic swelling, in all cases, it was found that the swelling ratio of neat PP and WPP melt composite increased with increasing shear rate, but for any given shear rates, the addition of wood particles and the use of rotating die caused decreases in swell ratio of the melts, the wood content being more well-defined than the die rotating speed.