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  • Table of Content
      20 October 2007, Volume 0 Issue 10 Previous Issue    Next Issue
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    Tensile Properties of Under-aged 3J21 Alloy at Low Temperatures
    JIN Xiao-ou, HE Shi-yu, ZHANG Song-yu
    2007, 0 (10): 3-6,17.  
    Abstract ( 261 HTML( PDF (1756KB)( 331 Citation
    The tensile properties of under-aged 3J21 alloy at room and low temperatures were studied on a universal tensile test machine.Moreover,a metallographic microscope and X-ray diffractometer were used to analyze the metallographic structure and physical phase of the alloy in a cold rolled and under-aged state.By employing a transmission electron microscope(TEM) the structure of the alloy under the above-cited two states was observed and the X-ray diffraction results being verified.An analysis of the microscopic structure of deformation near the tensile fracture of the under-aged alloy at different temperatures was also conducted.A scanning electron microscope was used to observe the tensile fracture.It was found that the room-temperature fracture of the under-aged 3J21 alloy was of a dimple,while the low-temperature fracture assumed a mixed rupture feature.With decreasing temperature,the characteristic feature of a brittle rupture became still more evident.In the microstructure near the low-temperature tensile fracture it has been found that the amount of twin crystals increased with a decreasing in temperature.The tensile strength and yield strength of the under-aged 3J21 alloy would increase conspicuously with a decreasing in temperature.The tensile strength increased while a relatively large margin of the elongation rate slightly decreasing.The influence of temperature on the tensile properties of the under-aged 3J21 alloy was discussed.
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    Stress Corrosion Cracking of 16MnR Low Alloy Steel in Anhydrous Ammonia Service
    LU Zhi-ming, CHEN Bing-bing, GAO Zeng-liang
    2007, 0 (10): 7-10.  
    Abstract ( 326 HTML( PDF (838KB)( 473 Citation
    The stress corrosion crack tests of 16MnR steel in anhydrous ammonia service have been done with the T shape wedge opening loading(T-WOL) constant displacement specimens.A group of eight specimen was used in the tests,every specimen was loaded by loading bolts to the desired KI value and then put into a special ammonia storage tank.The specimen were taken out from the tank periodically for crack length measurements,After total 3450 hours tests,the crack growth rate of the specimen were 0.08×10-8-3.54×10-8mm/s.Based on the tests and analysis,it can be concluded that the cracks of the 16MnR steel specimen in anhydrous ammonia service almost did not grow,threshold stress intensity factors KISCC are higher than 90 MPa√m.The stress corrosion crack mechanism and the effecting factors were also analyzed.
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    Study on the Electrically Conductive Silicone Rubber Filled with Acetylene Black
    JIAO Dong-sheng, REN Zong-wen, LIU Jun, SU Zheng-tao
    2007, 0 (10): 11-13,59.  
    Abstract ( 374 HTML( PDF (938KB)( 1294 Citation
    The electrically conductive properties of silicone rubber filled with acetylene black were studied.The results showed that the volume resistivity of the silicone rubber reduced while the acetylene black increased or the silica reduced,and the volume resistivity of the silicone rubber also reduced after heat treatment in air.
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    The Mechanical Properties and Microstructure of Porous Scaffold Made of HAp-(β-Ca3(PO4)2)-Si3N4 Biocomposite
    LIU Ai-hong, LI Ai-min, SUN Kang-ning
    2007, 0 (10): 14-17.  
    Abstract ( 406 HTML( PDF (1028KB)( 949 Citation
    HAp-(β-Ca3(PO4)2)-Si3N4 biocomposite with bigger pores and higher porosity was prepared by the method of organic foam soakage and pressureless sintering.The compressive strength,microhardness and porosity of the composite was mensurated.The composite has definite compressive strength and higher porosity which exceed 45%.With the increasing of Si3N4 the porosity of the composite expressed ascending trend but the compressive strength and microhardness decreased first and ascended later.The fracture mode of the composite was observed by SEM.The pores are penetrative and the diameter of most pores in the composite is between several micron and five hundred micron.The porosity and compressive strength of the scaffold should be desirable for bone tissue engineering.
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    Determination of Local Constitutive Properties of Welded Joints in Aluminium Alloy Using Double Holes Microshear Test
    ZHU Liang, REN Guo-song, LONG Lin, CHE Hong-yan
    2007, 0 (10): 18-22.  
    Abstract ( 352 HTML( PDF (1070KB)( 400 Citation
    Welded joints in aluminum alloy exhibit heterogeneity of mechanical properties.Local properties determination within the different constituents is necessary to improve the material processing,and to numerically evaluate the component performance such as crash simulation.The present work is concerned with a new approach for determining local material constitutive properties of welded joints in aluminum alloy.In this method,drill the double holes in the two sides of the point to be determined in welded joints,load material bridge by an indentor until it is broken,record the response between applied load and indentor displacement.We can call this method as double holes microshear test.According to the load-displacement curve obtained experimentally from the double holes microshear test,the true stress-strain curve of local material was calculated by means of the inverse methodology of finite element computation.The distribution of true stress-strain curves within heat-affected zone was consequently determined for aluminium alloy welded joints.The determination results show that,in the dissolution zones the yield stresses are lower but the work hardening exponent is higher,and in over aging zones both the yield stresses and the work hardening exponent are lower.
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    Preparation and Mechanical Properties of Nano-crystal NdFeB/PE Shielding Composite
    YANG Wen-feng, LIU Ying, LI De-an, YANG Lin, LI Cong
    2007, 0 (10): 23-26.  
    Abstract ( 374 HTML( PDF (763KB)( 326 Citation
    Ultrasonic dispersion and surface treatment with coupling agents was processed for the submicro-diameter NdFeB.NdFeB/PE rare earth/polymer composite was prepared through melt blending.The microstructure,mechanical properties and shielding effectiveness of the composite were tested.The results indicate that NdFeB can improve the tensile modulus and micro-hardness of PE and when the volume ratio of submicro-diameter NdFeB was 35%-40%,the tensile strength of PE increased too.But in the same time,submicro-diameter NdFeB will reduce the plasticity and toughness of PE.The improvement of tensile strength of the composite came from the interfacial interaction of PE and submicro-diameter NdFeB.
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    Numerical Simulation of Adiabatic Shear and Temperature Field in Hat-shaped Specimens
    JI Jian-ping, CAI Hong-nian, LI Shu-kui
    2007, 0 (10): 27-30.  
    Abstract ( 381 HTML( PDF (621KB)( 694 Citation
    Appropriate model and space discretization were chosen to simulate the loading process of specimens conducted on the Split Hopkinson Pressure Bar(SHPB) in two-dimension,and the adiabatic shear deformation course of the hat-shaped specimen under high strain rate was obtained.Based on the criterion of the formation of adiabatic shear to Stress Collage,the rule of adiabatic shear deformation was analyzed,the simulated stress-time curves and strain-time curves were employed to calculate the temperature field,the type of the shear bands was determined,and the results of numerical simulation are consistent with the experimental results.
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    Research on Bauschinger Effect of X70 Acicular Ferrite Pipeline Steel Plate
    LONG Ming-jian, YU Hao, YIN Yu-qun, NIU Tao, YANG Xu-ning, KANG Yong-lin
    2007, 0 (10): 31-34,44.  
    Abstract ( 306 HTML( PDF (526KB)( 528 Citation
    Bauschinger effect of X70 acicular ferrite pipeline steel with niobium microalloy produced by thermomechnical controlled process technology was investigated.The experimental results is shown showed that the maximum value of Bauschinger effect is about 17MPa when the pre-compressive strain is about 1.2%.The Bauschinger effect of this pipeline steel is smaller than that of other steels,it is because that there are complex phases in the steel and the phases yield non-simultaneously.
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    Tribological Properties and Mechanism of Cu Nanoparticles
    YU He-long, XU Yi, SHI Pei-jing, XU Bin-shi, WANG Xiao-li, LIU Qian
    2007, 0 (10): 35-38,48.  
    Abstract ( 288 HTML( PDF (1323KB)( 499 Citation
    The tribological properties of Cu nanoparticles as lubricating oil additive were evaluated on a facing tester.The morphology,element distribution and micro mechanical property of the worn surface were investigated by means of scanning electron microscopy(SEM),energy dispersive spectrometry(EDS) and nanoindentation tester.The results show that the wear resistance and friction reduction properties of 650SN mineral oil are improved markedly by adding Cu nanoparticles.The friction surface temperature lubricated by nanocopper additive is clearly lower than that lubricated by 650SN.A protective copper film is generated on the rubbed surface,which has lower hardness than 45# steel and contributes to better tribological properties.
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    Study on Ni-P-(Ni/SiC)P Electroless Composite Coatings
    SU Hui, CAI Wei, CAO Mao-sheng
    2007, 0 (10): 39-41,64.  
    Abstract ( 328 HTML( PDF (562KB)( 371 Citation
    In order to decrease the high cost of applications of naked(SiC)P,(SiC)P was surface-modified to(Ni/SiC)P by a simple electroless plating,then(Ni/SiC)P particles were incorporated into the Ni-P plating solution to prepare Ni-P-(Ni/SiC)P electroless composite coatings.The microstructure and properties of the Ni-P-(Ni/SiC)P electroless composite coatings were investigated by metallographic microscope,scanning electronic microscope(SEM),energy dispersive spectrum(EDS) and micro-sclerometer.Compared with the Ni-P coatings and the Ni-P-(SiC)P coatings,the results show that the Ni-P-(Ni/SiC)P electroless composite coatings has many merits such as the homogenous composition,thick coatings,high hardness and good wear-resisting properties,etc.The electroless plating method is very simple and the cost is very low,which may be avail to the further research of(SiC)P reinforced the alloy coating and metal matrix composite.
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    The Influence Factors of the Crystal Separating of MgO-Al2O3-SiO2 Glass-ceramics
    YANG Juan, DU Yong-guo, LI Xiao-dong, ZHOU Wen-yuan
    2007, 0 (10): 42-44.  
    Abstract ( 434 HTML( PDF (190KB)( 870 Citation
    The DSC technology was used to investigate the affecting factors for the crystal separating of the MgO-Al2O3-SiO2 glass-ceramics,including the component of material,the melting temperature of glass and the material state.The factors benefit to the low temperature sintering of the glass-ceramic include the relative high content of Mg2+,relative low melting temperature and the powder state with many flaws.These factors make it possible to be used as the low temperature co-fired ceramic substrate.
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    Effect of Fabric Structure on Mechanical Properties and Microstructure of Cf/SiC Composites
    ZHOU Chang-cheng, ZHANG Chang-rui, ZHOU Xin-gui, HU Hai-feng, ZHANG Yu-di
    2007, 0 (10): 45-48.  
    Abstract ( 313 HTML( PDF (535KB)( 289 Citation
    Carbon fiber reinforced silicon carbide composites were fabricated via infiltration and pyrolysis of precursor.The effects of different fabric structure on mechanical properties and microstructure of Cf/SiC composites were investigated.The results show that 2.5D fabric structural composites is superior to other three fabric structural composites remarkably on the aspect of mechanical properties.The flexural strength of 2.5D reached 406.25MPa,compared to three dimensional four direction(3D-4d) for 128.80MPa,and three dimensional five direction(3D-5d) for 159.74MPa and three dimensional six direction(3D-6d) for 150.42MPa.And the results were analyzed thoroughly from the point of view of textile technics.
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    The Effect of Sandwich Clay About Desorption Properties of Water-release Coated Fibre
    ZHANG Zeng-zhi, CAO Peng, ZHANG Ji-fei, ZHANG Yu-xiao, FANG Fang, YANG Lei-gang
    2007, 0 (10): 49-54.  
    Abstract ( 289 HTML( PDF (1443KB)( 375 Citation
    The water-release coated fibre is the key of achieving controllable water-release in fibre composite material,the additive in coated material is sandwich clay.The effect that three kinds of different clay additive to desorption properties of the water-release coat was studied through comparing with different water-release coated fibre’s water-release rules.The structure,the competence of holding water and the rule of H2O molecular adsorbed and released in different water-release coated fibre were analysed by thermal multi-analyzer,stereoscan photogragh,microscopic image analyzer and moisture rapid-testing equipment.The result of the experiment indicates that controllable water-release rules of H2O molecular can be fulfilled by water-release coated fibre of three kinds of clay,and the water-release coated fibre which was treated by additive(common clay) is better than others in meet controllable water-release.
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    Synthesis of Surface Oxidized and Dispersible Carbon Nanotubes by Chemical Vapor Reactions
    ZHONG Xiao-hua, FENG Jian-min, QIAO Xiao-hua, HOU Feng, LI Ya-li
    2007, 0 (10): 55-59.  
    Abstract ( 374 HTML( PDF (1174KB)( 563 Citation
    Introduction a small amount of water into the reactions system of ethanol and ferrocene in the solvent injection catalytic chemical vapor reactions yielded surface oxidized,highly crystallized and large hollow size multiple walled carbon nanotubes in argon flow.The nanotubes thus produced is dispersible in organic solvents like ethanol,benzene,toluene and xylene.High resolution transmission electronic microscopy observation revealed the existence of defects in the surface graphite layers of the nanotubes,but the inner graphite layers were well aligned and highly crystallized structures.X-ray photoelectronic spectrum(XPS) analysis detected the existence of carbon-oxygen bonds.Therefore,the water added not only activated the catalysts,increased the nanotube yield,but also oxidized the surface of the nanotubes.Oxidization processing of carbon nanotubes to dispersible materials is the key step towards their applications.This was previous done by post-processing nanotubes such as strong acid oxidizing or thermal oxidizing,which however,resulted in structural damage of the materials,hence degrading their properties.The present synthesis enables one-step yield of the surface oxidized and dispersible nanotubes which is of significance to their processing and the relevant applications.
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    Effects of Process Control Agents on Characteristics of Mechanically Alloyed Fe-48Al Powders
    SONG Hai-xia, WU Yun-xin, TANG Chuan-an, LIANG Ji
    2007, 0 (10): 60-64.  
    Abstract ( 376 HTML( PDF (997KB)( 443 Citation
    This paper dealt with the effects of process control agents(PCA),i.e.,ethanol and stearic acid on the characteristics of mechanically alloyed Fe-48Al powders.The particle size and particle morphology of the ball milled powders were investigated by means of laser mastersizer and scanning electron microscope,and their microstructures were examined by X-ray diffractometer before and after heat treatment.The results indicate that,compared with stearic acid,ethanol facilitates faster mechanical alloying of Fe-48Al,yielding much finer and more irregular plate-like powders.When using stearic acid as PCA,however,the milled powders tend to become thick plates or near-spherical particles.The milled powders with either ethanol or stearic acid as PCA remain a solid solution structure even after 12h milling,but both transform to FeAl(B2) intermetallic after subsequent vacuum annealing at 1100℃,during which more Al2O3 is formed in the ethanol milled powders.
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    Study of Phase Transformation Law for 600MPa High Strength and Toughness Oceanic Weather Resistant Steels
    WANG Jian-ze, KANG Yong-lin, YANG Shan-wu, ZHOU Jian
    2007, 0 (10): 65-67,71.  
    Abstract ( 276 HTML( PDF (472KB)( 260 Citation
    Gleeble-1500 thermo-simulation machine was employed to study phase transformation for 600MPa(Yield strength) high strength and toughness oceanic weather resistant steels.Effect of cooling rate on microstructure was analyzed.The results showed that the starting temperature of phase transformation is 550-650℃ and the ceasing temperature of phase transformation was 440-530℃.Microstructure conformation with cooling rate was levity.
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    Study of High Temperature Protective Performance of Composite Coating on K3 Superalloy
    ZHANG Peng-fei, LI Jian-ping, CAI Yan, LU Feng
    2007, 0 (10): 68-71.  
    Abstract ( 309 HTML( PDF (403KB)( 320 Citation
    The NiCrAlYSi coatings and NiCrAlYSi+AlYSi composite coatings were deposited by ARC ion plating(AIP) on K3 superalloys.The high temperature oxidation behaviors at 1100℃ and the gas hot corrosion behaviors at 900℃ of two kinds of coatings were studied.The results indicate that the NiCrAlYSi+AlYSi composite coatings have the more excellent high temperature oxidation resistance than NiCrAlYSi coatings,but the NiCrAlYSi coatings have the more excellent gas hot corrosion resistance.
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    Study on Preparing Methods for Nanoparticle Composite Electro-brush Plating Solution
    HU Zhen-feng, XU Bin-shi, DONG Shi-yun
    2007, 0 (10): 72-75,80.  
    Abstract ( 335 HTML( PDF (664KB)( 225 Citation
    A new composite method,named high-energy-mechanical and chemical method(HEMCM),was used to deconcentrate the ceramic nanoparticles within metal matrix solution.Comparing with the other methods,such as supersonic method,mechanical method or chemical method,much more nanoparticles were in nanometer scale in the composite solution after prepared by HEMCM.And the nanoparticles can suspend steadily as longer as twenty hours.Furthermore,most of the particles in composite solution were in nanometer scale after one month.What’s more,the proportion of nanoparticles is much higher in the coating prepared by this method.The surface of the coating is even,compact and smooth.The micro-hardness increases by 15%-30%.
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    Synthetic Evaluation on Stress Corrosion Testing Methods of High Strength Aluminum Alloys
    LIU Ji-hua
    2007, 0 (10): 76-80.  
    Abstract ( 766 HTML( PDF (1123KB)( 1971 Citation
    The stress corrosion testing methods of high strength aluminum alloys are reviewed.The principles and applications of these methods are presented.The advantages and shortcomings of those methods are analyzed.Because only one method can not evaluate the stress corrosion properties of aluminum alloys comprehensively,it would be better to measure aluminum alloys with different testing methods mentioned.
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