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      20 June 2011, Volume 0 Issue 6 Previous Issue    Next Issue
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    Effect of Ce on Modification of Primary Mg2Si Crystals in Hypereutectic Mg-Si Alloy
    DU Jun, LU Xinyu, LI Wenfang
    2011, 0 (6): 1-4.  
    Abstract ( 369 ( PDF (1416KB)( 246 Citation
    The hypereutectic Mg-Si alloy was modified by rare-earth element of Ce using Mg-20%(mass fraction,the same below)Ce master alloy.The effect of Ce addition content on the modification of the primary Mg2Si crystals and its modification mechanism were investigated in the present study.The results show that the primary Mg2Si crystals could be effectively modified from coarse dendritic morphologies to polygonal particles with irregular shape when the adding content of Ce was increased to over than 0.4%.Over modification of the primary Mg2Si crystals was not found even if the Ce content was increased to 2.0%.The modification mechanism should be associated with the enrichment of Ce on the growth facets of the primary Mg2Si crystals.The preferred growth manner of the primary Mg2Si crystals was depressed,while another type of growth,isotropic growth manner,was enhanced in the modified hypereutectic Mg-Si alloy.
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    Modification of Benzoxazine with Aluminum Hydroxide and Flame Retardancy Improvement
    LING Hong, YE Xiaozhou, GU Yi
    2011, 0 (6): 5-10.  
    Abstract ( 408 ( PDF (1340KB)( 470 Citation
    Benzoxazine(BOZ)/aluminum hydroxide(ATH) castings were prepared,and the properties of polybenzoxazine were investigated.The results show that when the mass fraction of aluminum hydroxide is more than 20%,flame retardancy of polybenzoxazine/ATH can achieve the UL-94V0 grade.Differential scanning calorimetry(DSC) and dynamic mechanical analysis(DMA) test show that with aluminum hydroxide the exothermal enthalpy of ring-opening curing reaction of benzoxazine decreases apparently and the glass transition temperature of the polybenzoxzine slightly increased.Thermal gravimetric analysis(TGA) and scanning electron microscopy(SEM) test results show that when heated above 200℃,the endothermic decomposition of aluminum hydroxide with water release to enable the polybenzoxazine to lower the temperature and to higher char yield,and aluminum oxide generated over the polybenzoxazine carbon surface isolated air to prevent combustion.
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    Experimental Investigation and Numerical Simulation on Mechanical Properties of Notched Metallic Panels Repaired with Bonded Composite Patch
    LI Shaochun, XIONG Junjiang
    2011, 0 (6): 11-16.  
    Abstract ( 405 ( PDF (978KB)( 309 Citation
    Static strength tests of notched aluminum alloy panels repaired with bonded composite patch were conducted to determine the load-displacement curves and to understand failure mode and mechanism as well as to investigate the effects of the behaviour of adhesives,mechanical properties and thickness of composite patch on static strength of repaired panels.The three-dimensional finite element model was established to simulate the load-displacement curves and stress patterns of repaired panel,demonstrating the valid and practical use of the proposed model.From the simulated stress patterns and strength criterion as well as failure mode,location and strength were predicted,and the obtained results have a good agreement with the experiments.
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    Effects of Al Content and Homogenization on Microstructure of the AZ Series Alloys
    PENG Jian, L Binjiang, ZHU Xi, PAN Fusheng
    2011, 0 (6): 17-22.  
    Abstract ( 355 ( PDF (1766KB)( 219 Citation
    In order to get extruded magnesium alloy with uniform microstructure,it is important to understand the effects of the content of alloying element and the homogenization annealing on the deformed microstructure.The AZ10,AZ31,AZ61 and AZ91 magnesium alloys were deformed with simulated extrusion system on Gleeble-1500D simulator.The results show that with homogenization annealing of 400℃/12h,the AZ10 and AZ31 alloys are in single solid solution phase,the AZ61 alloy has fine β phase particles inside the grain,while the AZ91 alloy has coarse β phases both inside the grains and on the grain boundary.After the extrusion with temperature of 390℃ and extrusion ratio of 20.3,the extruded alloy with homogenization annealing before extrusion has more uniform grains in size,while the extruded alloy without previously homogenization annealing has non-uniform structure consisting deformed strips and fine grains.
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    On the Measurement of Friction Coefficient of Ti-6Al-4V Titanium Alloy Utilizing the Hot Compression Test of Ring and FE Simulation
    TAI Qingan, LI Xiaoguang, LI Zhihua, LIU Yan, ZHU Yanchun, ZENG Weidong
    2011, 0 (6): 23-26,31.  
    Abstract ( 370 ( PDF (499KB)( 267 Citation
    A study of the friction coefficients is presented for TC4 titanium alloy at high temperature deformation using ring compression test and finite element(FE) simulation.FE simulations were used to derive the friction calibration curves,and a series of ring compression tests were carried out on the conditions of glass lubricant and dry friction to constitute the relationship between reduction in inner diameter of ring and reduction in height.It is found that the friction coefficients of TC4 titanium alloy for glass lubricant and dry conditions are determined to be about 0.32 and 0.58,respectively,which are in agreement with research results at home and abroad.The method that deriving the friction calibration curves using FEM,is not only superior to analytical methods,which can not consider the characteristics of materials,properties of touched surfaces and influence of temperature and strain rate on deformation,but also a special effectively method to determine the friction coefficients at the interface of die/workpiece during high temperature deformation.
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    Effect of Supersonic Power and pH Value on the Structure and Electrochemical Performance of Y Doped Nano-Ni(OH)2
    WU Shanggai, ZHU Yanjuan, ZHANG Zhongju, ZHOU Zhuojun, YE Xiancong, ZHENG Hanzhong, LIN Xiaoran, BAO Jie
    2011, 0 (6): 27-31.  
    Abstract ( 423 ( PDF (1085KB)( 172 Citation
    Nano-Ni(OH)2 doped with yttrium was prepared by supersonic co-precipitation method.The crystal structure and electrochemical performance affected by supersonic power and pH value were characterized.The results indicate that the nickel hydroxides prepared under different ultrasonic power were co-existence with α and β phase,which were.As the supersonic power increases,the proportion of α-Ni(OH)2 increased initially and then decreased,but the particle size is converse.PH value is very important to the formation of crystalline phase.Lower pH value is beneficial to formation of α-Ni(OH)2,which is decreased with the pH value increased.However,the pH values have a slight effect on the reaction reversibility.Complex electrodes were prepared by mixing 8%(mass fraction) nickel hydroxides with commercial micro-size spherical nickel.The discharge capacities of electrodes increased initially and then decreased with the increase of superonic power.When the supersonic power is 60W and the pH value is 9,the sample has the largest discharge capacity,which reaches 358mAh/g at 0.5C rate.Furthermore,the sample(P=60W,pH=9) has better electrochemical performance and higher charge or discharge potential than the others.
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    Microstructure and Mechanical Properties of ZK60 Magnesium Alloy Produced by Equal Channel Angular Pressing
    HE Yunbin, PAN Qinglin, LIU Xiaoyan., LI Wenbin
    2011, 0 (6): 32-38.  
    Abstract ( 391 ( PDF (1949KB)( 254 Citation
    The equal channel angular pressing technology was employed to fabricate fine grained ZK60 magnesium alloys,the microstructure and mechanical properties of the alloys at various conditions were investigated,the effect of extrusion temperature and pressing passes on ECAP was studied.The results showed that the optimal temperature range for ECAP of ZK60 magnesium alloy was 210-240℃,where a well grain refinement can be achieved;with increasing the number of ECAP pass,the grain size of ZK60 was reduced accordingly,but after 4 passes,the grain size refinement effect was slowed down.The yield strength of ECAP deformed alloys was decreased compared with the as-extruded alloy.However,the elongation was increased after multi-pass pressing.
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    Preparation of Graphite Composite by Ti-Cu Alloy Pressureless Infiltration Method and Its Microstructure and Properties
    ZHANG Yading, ZHANG Tao
    2011, 0 (6): 39-42,47.  
    Abstract ( 497 ( PDF (799KB)( 232 Citation
    A titanium copper alloy infiltrated graphite composite was successfully synthesized by pressureless infiltration of Ti65Cu35 alloy into graphite preform.The infiltration was carried out at 1273-1373K in Ar atmosphere,and the infiltration time is 5-20s,then keep the temperature for 10 minutes to ensure the infiltration be finished completely.The investigation on the infiltrated composite by X-ray diffraction,scanning electron microscope and energy dispersive spectrometer indicates that the composite consists of C,TiC,Cu and TiCu,while TiC is the main product at the interface.Moreover,a reticular uniform distribution of TiC/Cu/TiCu in graphite matrix for the composite is identified.The article studied the density,porosity and friction coefficient of the materials before and after the infiltration.The result shows that the titanium copper alloy graphite has infiltrated 82% of the graphite preform's pores and improves its density from 1.602g·cm-3 to 2.653g·cm-3.The titanium carbide generated in the interface region between infiltrated alloy and the graphite matrix has high melting point and high hardness.It can not only improve the wetability of alloy and graphite to increase the bonding strength,but also greatly improve wear resistance of the composite material.
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    Influence of Plunge Depth of Shoulder on Interface Migration of Friction Stir Lap Welds
    WEI Peng, XING Li, XU Weiping
    2011, 0 (6): 43-47.  
    Abstract ( 397 ( PDF (1273KB)( 345 Citation
    Friction stir lap welds of 2mm thick plates of LF6 aluminum alloy were conducted using the cylindrical tool with left-hand thread,the influence of plunge depth of shoulder on interface migration of friction stir lap welds was investigated.The results show that the interfaces at the advancing side and retreating side of the welds move toward the upper surface of welds,when the interface at the retreating side is up to the top of weld,it will transfers horizontally to weld center and can be largest extended to the advancing side while the interface at the advancing side is only moved at the advancing side.The height of interface migration at the retreating side rises with the increase of the plunge depth of shoulder,but the height will be reduced when the plunge depth of shoulder is more than 0.18mm.The height at the advancing side augments with the increase of the plunge depth of shoulder.Micro-morphology of transferred interface was observed,the interface at the retreating side is not joining when it transfers upwards.And then it is intermittent distribution when it moves to the top of weld.Interface line becomes a tight joining when it transfers horizontally to weld center.The transferred interface at the advancing side is always continuous.
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    Study on Sintering Process of Porous Co-Cr-Mo Alloy for Artificial Joint
    QIAO Zhen, HE Juan, HUANG Yongling, LI Guohua
    2011, 0 (6): 48-51.  
    Abstract ( 484 ( PDF (908KB)( 396 Citation
    On the basis of moderately increasing sinter temperature to insure the bond strength between beads and joints,the microstructure and mechanical properties of casting Co-Cr-Mo alloy joints under different cooling regime were priority investigated.Group A of castings were vacuum sintered at 1280℃ and furnace cooled after original solution treatment.Group B was directly vacuum sintered at 1280℃and furnace cooled to 1200℃,finally cooling to room temperature with flowing Ar atmosphere.Group C slowly cooled in casting die without heat treating.Group D was solution treated between 1200-1240℃ and oil cooled.All above of them were as contrast samples with each others.The results showed that mechanical properties of the Group B casting Co-Cr-Mo joints met the technical requirement,after high-temperature vacuum sintering without solution treatment and fast argon gas cooling.Moreover,finer microstructure,smaller disperse carbide M23C6 were obtained by gas cooling.This trial and exploring process improved mechanical performance,increased pass percentage and excused from the solution treatment procedure,so it has actual significance of reducing cost and time as well as increasing product quality and productivity.
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    Penetration of Chlorine Ion in Organic Coating and Deterioration Process by Electrochemical Impedance Spectroscopy
    CHEN Jiacai, WANG Xudong, SUN Dongbai
    2011, 0 (6): 52-57.  
    Abstract ( 346 ( PDF (1355KB)( 249 Citation
    The penetration law of chloride ion in the fluorocarbon separate coating and the deterioration process of fluorocarbon coating were investigated by permeability test and EIS,respectively.The results show that the diffusion of chlorine ion in fluorocarbon separate coating have a time critical point.The spread of chlorine ion in coating reach a dynamic balance stage before the critical point,then the chlorine ion in coatings diffusion present linear increase trend.The permeability of chlorine ion in fluorocarbon coatings slower than fluorocarbon resin layer.And solution and temperature on the infiltration of chloride ion in fluorocarbon coating have clear influence on the transmission.The EIS result also indicates that the coating capacitance(Cc) all have ascendant trend.Besides,the artificial seawater had more corrosive effect than 3.5%(mass fraction)NaCl solution at 15℃.
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    Investigation of Plasma Treatment and Collagen Immobilization on the Surface of Poly(lactid-glycolide acid)
    CUI Yuan, DUAN Qian, LI Yanhui
    2011, 0 (6): 58-62.  
    Abstract ( 438 ( PDF (1265KB)( 152 Citation
    For collagen is a major component of the extracellular matrix,when the surface of poly(lactid-glycolide acid)(PLGA) is grafted with collagen,cytocompatibility of PLGA will be improved.Plasma treatment is selected to immobilize collagen on the surface of PLGA.Optimum power and treating time of plasma are determined by contact angle test.The results indicate they are 60W and 5min,respectively.XPS analysis reveals that carboxy groups on collagen are reacted with actived hydroxyl groups on the surface of plasma treated PLGA to form ester groups.Then collagen is immobilized on PLGA.Cytocompatibility evaluation of collagen immobilized PLGA(COL-PLGA) was carried out by seeding 3T3 cells on the surface of COL-PLGA.Quanlitative and quantitative analysis proved that cell adhesion and proliferation are improved after collagen grafting.Quantitative result is obtained by MTT assay in cell living period.
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    Study on the Structure and Performance of PVA-based Polyion Complex Membrane
    ZHANG Yanmei, MENG Pingrui, WANG Xiaohui, YU Haoqiang, LI Liangbo
    2011, 0 (6): 63-66.  
    Abstract ( 435 ( PDF (1043KB)( 319 Citation
    Polyvinyl alcohol(PVA)grafting polyvinyl ammonium chloride(PVA-g-PVAC) and PVA grafting sodium polyacrylate(PVA-g-SPA) self-assembled into PVA-based polyion complex(PPIC).The chemical structure of PPIC was identificated by IR.The SEM image of PPIC membrane showed that there was ordered porous morphology at the surface which was beneficial to water absorption.The thermostability of PPIC was tested by DSC.The water resistance of the PPIC membranes is the best when the pH of the assembly solution is 5(composited by equimolar counterions,pH approached or equaled to isoelectric point(IEP)).The water resistance of the PPIC membranes was improved with the increasing of annealing temperature and ethanol concentration.The results showed that the PPIC membrane was suitable for the separation of ethanol/water system.Meanwhile,the pervaporation of PPIC composite membrane was tested and showed that the permeation flux was 1485g·(m2h)-1 and the separation factor was 980 for wastewater of high concentration high concentration ethanol waste water(ethanol 93%(volume fraction)).
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    Influence of the Solidification Directions on Dendritic Structures in a Single Crystal Superalloy
    ZHANG Longfei, YAN Ping, ZHAO Jingchen, ZENG Qiang, HAN Fengkui
    2011, 0 (6): 67-71,76.  
    Abstract ( 403 ( PDF (1739KB)( 306 Citation
    In order to investigate the effect of solidification direction on dendritic morphology and primary dendritic arm spacing(PDAS) in Ni-based single crystal superalloy,seeding technique was applied to obtain the single crystal samples solidified in different orientations.The results indicated that when the deviation degrees from solidification direction to orientation were within 15°,dendrite morphology kept regular and primary dendritic arm spacing declined with deviation degrees increasing;excessively long secondary dendritic arms blocked the growth of vicinal primary dendritic arm when deviation degrees were up to 25°,leading to increase in PDAS.Owing to 2 and 3 dendritic arms orientated in preferential growth direction in crystals solidified in and orientation respectively,complex dendritic configurations are formed.
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    Load Model and Quantitative Characterization of Microarc Oxidation Pulse Supply
    ZHAO Yufeng, YANG Wei, YANG Shiyan
    2011, 0 (6): 72-76.  
    Abstract ( 290 ( PDF (925KB)( 264 Citation
    Based on the electrochemical theory and parameter fitting measure,the equivalent circuit model of electrobath load under pulse supply was researched to match microarc oxidation(MAO) pulse supply and its load.The theory model of supply load was obtained firstly by electrochemical impedance spectroscopy(EIS).And then quantitative analysis of equivalent circuit model was carried out by measuring step response of the load and curve fitting.The parameter values and their trends of the equivalent circuit in the whole MAO process were calculated.Finally simulation result according to these calculated parameters was compared to experimental curve and the rationality of the circuit model was illustrated.
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    Dynamic Mechanical Properties of Poly(phenylene sulfide)/Hydroxy Purified Multi-walled Carbon Nanotubes Composites
    JIANG Shengling, GU Xiaoyu, ZHANG Zhiyuan
    2011, 0 (6): 77-80.  
    Abstract ( 401 ( PDF (1435KB)( 209 Citation
    New polyphenylene sulfide(PPS) based composites have been fabricated by the incorporation of hydroxy purified multi-walled carbon nanotubes(MWCNTs-OH) via melt mixing.Temperature curves of dynamic mechanical thermo analysis(DMTA) revealed an increase in the storage modules,hence in the rigidity of the systems,with small addition of MWCNTs-OH and increasing MWCNTs-OH content.The α and β transition peak shifts to higher temperatures due to the restriction in chain mobility imposed by the hydrogen bond force between MWCNTs-OH and PPS chains.tanδ peaks height of α and β-transition get to be weakening with the increase of MWCNTs-OH content.
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    Effects of Horizontally Vibrating Mechanical Attrition on the Microstructure of Electrodeposition Cu Coatings
    FENG Changjie, DU Nan, WANG Chunxia, HE Yedong
    2011, 0 (6): 81-86,98.  
    Abstract ( 351 ( PDF (934KB)( 229 Citation
    The mechanical attrition(MA) was supplied in a traditional acid electroplating process of copper by the horizontal rolling and sliding of glass balls on the sample surface with a special vibrating frequency.The effects of vibrating frequency on the microstructure,grain refinement,deposition rate,porosity,as well as corrosion resistance in 3.5%(mass fraction) NaCl solution of the mechanical attrition enhanced electroplating(MAEE) were analyzed by SEM,XRD and AutoLab.The results show that,compared with the traditional electroplated(TEP) Cu coating,significant grain refinement,reduced porosity and enhanced corrosion resistance are exhibited for the MAEE Cu coatings.When the vibrating frequency is arranged in 1.0-4.0Hz,the change of frequencies has no obvious influence on the grain refinement of MAEE coatings.And when the frequency is set to 2.0Hz or 3.0Hz,due to the inhomogeneous MA of the balls,the properties of MAEE Cu coatings are inferior to those prepared at 1.0-4.0Hz,but still much better than TCP coating.The mechanism of horizontal vibrating frequency on the MAEE process was discussed.
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    Development of II-VI Semiconductor Quantum Structure Materials and Devices
    HAO Jianwei, ZHA Gangqiang, JIE Wanqi
    2011, 0 (6): 87-91.  
    Abstract ( 418 ( PDF (1031KB)( 721 Citation
    The basic concepts of quantum structure materials and devices were summarized,and the definition of quantum structure and the quantum size effect were introduced.Take example for the II-VI compound semiconductor,the effect of the quantum size effect upon exciton binding energy was introduced.Therefore,the II-VI compound semiconductor quantum structure materials such as quantum wells and quantum dots,and the application development of which in photoelectric detection devices,light emitting devices and solar cell field were analyzed generally.
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    Recrystallization of Single Crystal Nickel-based Superalloys
    MENG Jie, JIN Tao
    2011, 0 (6): 92-98.  
    Abstract ( 545 ( PDF (1996KB)( 518 Citation
    The single crystal nickel-based superalloys are mainly employed as turbine blades of gas turbine engines.However,recrystallization is one of major problems in the production and service of nickel-base single crystal superalloys.The effects of the parameters,such as temperature,heat treated time,deformation and compositions,on the recrystallization behavior have been reviewed.The influence of recrystallization on the creep and fatigue properties has been analyzed.And the methods for the control of recrystallization including recovery,erosion for removing the deformed surface,carbonization and coating have been discussed.Finally,the problems and the development of recrystallization of the single crystal nickel-based superalloys have been pointed out.
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