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      20 February 2015, Volume 43 Issue 2 Previous Issue    Next Issue
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    SiC Coating on Low Density Carbon/ Carbon Composites Prepared by Silicon Evaporation
    WANG Bing, TAN Yi, SHI Wei, LI Jia-yan, YOU Qi-fan
    2015, 43 (2): 1-6.   DOI: 10.11868/j.issn.1001-4381.2015.02.001
    Abstract ( 1058 ( PDF (3377KB)( 385 Citation
    A graphite coating was fabricated on low density carbon/carbon composites by a slurry coating technology. SiC coating was prepared using direct reaction of silicon vapor and graphite coating through silicon evaporation. The influence of evaporation temperature, evaporation time, atmosphere, silicon evaporation source and surface roughness of graphite coating on the micrograph, phase constitution, density, surface evenness and thickness of SiC coating were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the surface evenness of SiC coating increases gradually with the increase of evaporation temperature. Only SiC exists on coating surface at the evaporation temperature of 1550, 1650℃. Using silicon block as silicon source and argon as protective gas, the surface evenness of SiC coating is enhanced. The density and continuity of coating can be improved by reducing the surface roughness of graphite coating. With increasing evaporation time, the thickness and density of SiC coating gradually increases.
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    Effect of Excitation Current on Tensile Properties of Joint of MGH956 Alloy by In-situ Alloying TIG Welding
    LEI Yu-cheng, GONG Chen-cheng, LUO Ya, XIAO Bo, ZHU Qiang
    2015, 43 (2): 7-13.   DOI: 10.11868/j.issn.1001-4381.2015.02.002
    Abstract ( 917 ( PDF (4599KB)( 260 Citation
    The arc-ultrasonic was excited by modulating the TIG arc through high frequency and the homemade solder was filled in the weld as filler composite. The effect of arc-ultrasonic on pores, microstructures and mechanical properties of MGH956 alloy joints produced by arc-ultrasonic in-situ alloying TIG welding with different excitation current was investigated. The results show that when the excitation current is 10A, pores grow up obviously while the number of pores is reduced, moreover, the grains are coarse. When the excitation current increases to 20A, the number of pores sharply decreases, the grains are fine and uniform, and the particle reinforced phases are uniformly distributed in the weld. When the excitation current increases to 30A, the number of pores further decreases while the grains are coarsen. The tensile results indicate that the maximum tensile strength of the weld joint is achieved at an excitation current of 20A, which is 626MPa and reaches 87% of the base metal. The toughness of joints is improved obviously and the fracture surface changes from completely brittle fracture to ductile-brittle mixed fracture.
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    Properties of Cold Spray Al/Zn Coatings on High-strength Steel
    SHI Zhong-chuan, ZHANG Xiao-yun, CHEN Hao, DING Fang-zheng, YU Bo, TANG Zhi-hui, LU Feng
    2015, 43 (2): 14-19.   DOI: 10.11868/j.issn.1001-4381.2015.02.003
    Abstract ( 1098 ( PDF (2689KB)( 402 Citation
    Al/Zn coatings could be deposited by cold gas dynamic spray on high-strength steel (300M) surface. The morphology and microstructure of coating were analyzed by scanning electronic microscope (SEM),energy dispersive spectroscopy (EDS) and microhardness tester. The corrosion resistance was investigated by neutral salt-spray accelerated test and atmospheric exposure test and fatigue test results of Al/Zn coatings were compared with 300M substrate. All the results indicate that Al/Zn coatings porosity is 0.8%, the microhardness is 59.8HV0.025, the salt spray resistance reaches 1000h and it can reach 770h even the coatings fails, the atmospheric exposure test achieves 12 months and no influence over 300M substrate fatigue.
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    Comparison Between Laser-MAG Hybrid Welding and MAG Welding of S355J2W+N Steel
    GU Xiao-peng, DUAN Zhen-zhen, DENG Gang, GU Xiao-yan
    2015, 43 (2): 20-25.   DOI: 10.11868/j.issn.1001-4381.2015.02.004
    Abstract ( 1219 ( PDF (3870KB)( 315 Citation
    Welding research on thick low carbon steel plate of S355J2W+N was done by using laser-MAG hybrid and MAG welding. Microstructure and mechanical properties of the joints were analyzed. The results show that the hybrid and MAG welded joint is composed of welding seam zone, over-heated zone, annealed zone and local annealed zone. The cross-section of hybrid welded joint shows a goblet appearance and the wire accumulation and width of HAZ are significantly reduced compared with MAG welding. The Widmanstaten structure in over heated zone increases a little bit due to fast cooling speed in hybrid welding. The hardness is higher than that of MAG welding. There is no significant difference in the tensile strength and bending property between hybrid welded joint and MAG welded joint. The tensile strength and bending property of hybrid welded joints and MAG welded joints both meet production standards.
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    Bending Performance of Polymer Composites Single Lap Joints Reinforced by Z-pin
    DONG Xiao-yang, LI Yong, LI Wen, ZHANG Xiang-yang, XIAO Jun
    2015, 43 (2): 26-34.   DOI: 10.11868/j.issn.1001-4381.2015.02.005
    Abstract ( 740 ( PDF (2884KB)( 304 Citation
    In order to investigate the effect of Z-pin on the bending performance of polymer composites single lap joints, Z-pin reinforced single lap joint samples with different parameters were prepared. The mechanical properties were tested under three point bending. The results show that at a diameter of 0.5mm, the bending load of single lap joints increases with increasing Z-pin volume fraction from 0% to 1.5%, and decreases with further increasing Z-pin volume fraction from 1.5% to 3.0%. The bending load with 1.5% volume fraction reaches the peak value of 1303.2N. At a volume fraction of 1.5%, the bending load of single lap joints increases with increasing Z-pin diameter from 0.3mm to 0.7mm. Compared with 0.3mm sample, the bending load of single lap joint with 0.7mm Z-pin is 27.9% higher. The implant angles of Z-pin have little influence on the bending performance of single lap joints. Besides, the bending performance is enhanced with the increase of overlap length.
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    Structure and Properties of AZ31B/Cu Diffusion Interface Under Electric Field
    DONG Feng, CHEN Shao-ping, HU Li-fang, FAN Wen-hao, MENG Qing-sen
    2015, 43 (2): 35-40.   DOI: 10.11868/j.issn.1001-4381.2015.02.006
    Abstract ( 979 ( PDF (2452KB)( 213 Citation
    The diffusion bonding of AZ31B/Cu was carried out by field activated diffusion bonding technique (FADB). The microstructure, phase composition of each layer and interface element distribution across the diffusion dissolution layer were analyzed by means of SEM, EDS and TEM. The shearing strength of the bonded interface was evaluated by universal testing machine. The results indicate that complete metallurgical bonding between AZ31B/Cu is reached. When the diffusion temperature is lower than 475℃, the diffusion-dissolution layer is composed of MgCu2, and Mg2Cu and MgCuAl, in which Mg2Cu has the lowest shearing strength. When the diffusion temperature is 500℃, the diffusion-dissolution layer is composed of Mg2Cu, α-Mg+Mg2Cu eutectic and MgCuAl phases, in which α-Mg+Mg2Cu eutectic structure becomes the new weakest section in whole joint and further decrease the shearing strength of the whole joint due to its brittleness. When the diffusion temperature is 450℃, the interfacial shearing strength increases first, then decreases with the increase of holding time, and it reaches the maximum strength of 40.23MPa when the holding time is 30min.
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    Hot Deformation Behavior and Microstructure Evolution of GH4706 Alloy
    HUANG Shuo, WANG Lei, ZHANG Bei-jiang, ZHAO Guang-pu
    2015, 43 (2): 41-46.   DOI: 10.11868/j.issn.1001-4381.2015.02.007
    Abstract ( 945 ( PDF (2957KB)( 219 Citation
    The hot deformation behavior of GH4706 alloy was investigated by compressive deformation performed on Gleeble 3800 machine at deformation temperature of 900-1150℃ and at strain rates of 0.001-1s-1. The results show that the true stress-true strain curves exhibit flow softening characteristic, the peak stress and peak strain decrease gradually with the increase of deformation temperatures or decrease of strain rates. Further, the constitution relationship is modeled using the hyperbolic-sine Arrhenius-type equation. The activation energy and stress exponent are 435.36kJ/mol and 4.13, respectively. The mechanisms of microstructure evolution are related to Z parameter, the domain mechanism is dynamic recovery at higher Z; while is dynamic recrystallization and grain coarsening at lower Z. The critical value of lnZ which the microstructure is completely dynamic recrystallization without grain coarsening is 35.
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    Synthesis of Iron Oxide Nanoparticles Coated with MPEG and Washing Method
    SHENG Dian, ZHANG Bao-lin, TU Zhi-jiang, XIE Song-bo, WANG Ming
    2015, 43 (2): 47-52.   DOI: 10.11868/j.issn.1001-4381.2015.02.008
    Abstract ( 853 ( PDF (3428KB)( 325 Citation
    The superparamagnetic iron oxide nanoparticles (SPIONs) were synthesized by thermal decomposition of iron(Ⅲ) acetylacetonate (Fe(acac)3) in methoxy polyethylene glycol (MPEG), which was used as solvent, reducing and modifying agent. The SPIONs were collected through washing with saturated salt water. Dialysis was used to remove the residual NaCl on the surface of SPIONs. The samples were characterized using XRD, TEM, HRTEM, SQUID, ICP-MS, TGA, FT-IR, and particles & Zeta potential analyzer. The results show that the residual NaCl on the surface of the samples is removed successfully after dialysis treatment. The prepared SPIONs, having high crystallinity, show superparamagnetic behavior at 300K with saturation magnetization of 53.7A·m2·kg-1. The surfaces of SPIONs are modified with MPEG which provides good water dispersibility. Excessive organic solvent is removed by salt bridge extracting method. The prepared SPIONs may have potential applications in the biomedical field.
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    Effects of Si Content on Structures and Properties of Centrifugal Al-8.5Ni-xSi Composites
    LIN Xue-dong, LIU Chang-ming, LU Jian-bo
    2015, 43 (2): 53-60.   DOI: 10.11868/j.issn.1001-4381.2015.02.009
    Abstract ( 775 ( PDF (6325KB)( 189 Citation
    The microstructures of the centrifugal composites Al-8.5Ni-xSi tubes were observed. Effects of Si content on the microstructures, hardness and wear-resistance of the tubes were investigated. The results show that the Al-8.5Ni-9Si tube consists of an outer layer containing some primary NiAl3 and the inner layer of Al matrix. While the Al-8.5Ni-14Si, Al-8.5Ni-19Si tubes both have an outer layer segregating many primary NiAl3 and Si particles, the middle layer having no particles and the inner layer containing a few primary NiAl3 and Si particles. The particle volume fractions in the reinforcement layer of the Al-8.5Ni-xSi tubes increase gradually as well as the hardness and the wear resistance with the Si content increasing from 9% (mass fraction, the same below) to 14% and 19%. The centrifugal migration of NiAl3 and the centripetal movement of Si in the centrifugal field play an important role in the formation of the Al-8.5Ni-xSi tubes which have various structures.
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    Dynamic Compressive Properties and Failure Behaviour of Rolled AZ31 Magnesium Alloy Sheet (4mm)
    LIU Zheng, DONG Yang, MAO Ping-li, YU Jin-cheng
    2015, 43 (2): 61-66.   DOI: 10.11868/j.issn.1001-4381.2015.02.010
    Abstract ( 792 ( PDF (4248KB)( 228 Citation
    To investigate the dynamic compressive properties and failure behaviour of the rolled AZ31 magnesium alloy sheet (4mm), the dynamic compressive test was carried out using split Hopkinson pressure bar(SHPB) at ambient temperature under the strain rates from 500s-1 to 2600s-1.The compressed specimens were analyzed by metallographic microscope and scanning electron microscope. The dynamic compressive properties and failure behaviour of the rolled AZ31 magnesium alloy sheet (4mm) along rolling direction(RD), transverse direction(TD) and normal direction(ND) were discussed. The results show that the dynamic mechanical properties of the rolled AZ31 magnesium alloy sheet (4mm) exhibit strong anisotropy. The properties along RD and TD are similar while the dynamic strength along ND is the largest. The dynamic compressive fracture mechanism of the rolled AZ31 magnesium alloy sheet (4mm) is cleavage fracture. The deformation mechanism is that tensile twinning {1012}〈1120〉 are activated along RD and TD compression; compressive twinning {1011}〈1120〉 are activated along ND compression.
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    Influence of Ultra Fast Cooling Process on Corrosion Resistance of High Nb X80 Pipeline Steel
    ZHOU Feng, WU Kai-ming
    2015, 43 (2): 67-72.   DOI: 10.11868/j.issn.1001-4381.2015.02.011
    Abstract ( 946 ( PDF (2187KB)( 230 Citation
    According to the NACE standard,the corrosion resistance of the new type ultra fast cooling process produced X80 pipeline steel to sulfide stress corrosion cracking (SSCC), hydrogen induced cracking (HIC) and CO2 was investigated. SSCC corrosion experiments show that critical cracking stress value is about 65%σs(390MPa),over the critical value, corrosion sensitivity of the test specimen becomes higher, and the corrosion resistance becomes poor. Under the 95% σs loading level, the stress sensitivity is extremely high. HIC corrosion experiments show that the crack sensitive percentage, the crack length percentage and the crack thickness percentage is all zero, CO2 corrosion resistance experiments show that when the pressure of CO2 is 0.1MPa, the average corrosion rate is 0.6843mm/a. The research shows that the X80 pipeline steel produced by the ultra fast cooling process have superior resistance to SSCC, HIC and CO2.
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    Effect of Low Temperature Plasma Treatment on Surface Properties of Aviation Fluorosilicone Rubber
    CHEN Yu-ru, WANG Yun-ying, MENG Jiang-yan, FAN Jin-juan, SUN Xu
    2015, 43 (2): 73-78.   DOI: 10.11868/j.issn.1001-4381.2015.02.012
    Abstract ( 1049 ( PDF (3342KB)( 274 Citation
    Surface of the aviation vulcanized fluorosilicone (FS6265) rubber was treated by low temperature plasma treatment with Ar and O2 atmospheres. Chemical element of surface of FS6265 was analyzed by means of X-ray photoelectron spectroscopy (XPS). The static contact angle, surface energy, and the peel strength were used to characterize the condition of FS6265. Surface morphology and surface roughness were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results show that the contact angle of FS6265 decreases from 101.5° to 19°, surface energy increases from 19.3mJ·m-2 to 73.2mJ·m-2 when it's treated by Ar plasma treatment. The water contact angle declines to 25.5°, and the surface energy improves to 70.6mJ·m-2 after being treated by O2. The images of SEM and AFM show that FS6265 surface roughness increases. XPS shows that the concentration of carbon element and inert fluorine element decreases, oxygen element improves greatly after LTP treatment,double bonded carbon atoms (C=O) and C—OH function groups are found in the surface. In addition, the time effectiveness of plasma treatment is obvious and for FS6265,surface energy change disappear after treated in Ar,O2 atmospheres and then being placed 12h and 8h.
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    Heat Generation Rule and Fatigue Performance Prediction of 443 Ferritic Stainless Steel Under Tension-tension Cyclic Loading
    ZHANG Jie, YAN Zhi-feng, WANG Wen-xian, WANG Zhi-bin, WANG Kai, ZHANG Hong-xia, ZHANG Xin-bao
    2015, 43 (2): 79-84.   DOI: 10.11868/j.issn.1001-4381.2015.02.013
    Abstract ( 835 ( PDF (1934KB)( 211 Citation
    The surface temperature field of 443 ferritic stainless steel was studied using infrared thermography during fatigue testing.ΔT-Nf curve method was put forward to predict the fatigue life. The results show that the ultimate temperature increment is ΔT=3.18℃,that is, when ΔT is more than 3.18℃,fatigue fracture occurs on the specimen, compared with the actually measured temperature increment of 3.49℃, the error is 8.89%. The percentage difference between the experimental result 284.45MPa and the predicted result 277.97MPa is 2.28% when fatigue cycles is up to 5×106.
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    Effects of Alternating Current on Corrosion Behavior of X80 Pipeline Steel in Acid Soil Environment
    ZHU Min, LIU Zhi-yong, DU Cui-wei, LI Xiao-gang, WANG Li-ye
    2015, 43 (2): 85-90.   DOI: 10.11868/j.issn.1001-4381.2015.02.014
    Abstract ( 1204 ( PDF (5253KB)( 320 Citation
    The effects of alternating current(AC) current density(0-1000A/m2) on the corrosion behavior of X80 steel in Yingtan acid soil simulated solution was studied by electrochemical test, immersion test and surface characterization technique. The results show that with the increase of AC current density, the corrosion rates of X80 steel increase. The corrosion rates increase slightly and the corrosion potentials of X80 steel rapidly shift negatively, with an increasing AC current density less than 100A/m2. When the AC current density is greater than 100A/m2, the corrosion rates increase rapidly and the corrosion potentials of X80 steel are roughly equal. With the increase in AC current density, the corrosion forms evolve from uniform corrosion to pitting corrosion. Moreover, the current fluctuation on the cathodic polarization curves becomes more obvious and the anode current densities increase. The corrosion product of X80 steel under AC application can not protect the substrate, because of its loose and multi-cracked characteristics.
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    Influence of Corrosion Environments on Corrosion Fatigue Property of Pre-corroded Aluminum Alloy
    MA Shao-hua, HUI Li, ZHOU Song, XU Liang, ZHU Yong-hui
    2015, 43 (2): 91-95.   DOI: 10.11868/j.issn.1001-4381.2015.02.015
    Abstract ( 994 ( PDF (2484KB)( 331 Citation
    The influence of different environments on corrosion fatigue property of pre-corroded 7XXX aluminum alloys was investigated via axial load fatigue test under different environments. The results show that water in fuel tank environment has the biggest effect on the specimens fatigue life among all the corrosion environments and followed by the saline environment, the wet air and the laboratory air. When stress ratio R is 0.5 and 0.06, the fatigue life of the specimens in the wet air are slightly lower than those in the laboratory air, the decreasing amplitude increases with the decrease of stress. Fatigue life of the specimens in the saline environment and water in fuel tank are almost the same at low stress level. When stress ratio R is -1, the fatigue life of the specimens in the saline environment are always slightly lower than those in the water of fuel tank, and the fatigue life in the wet air are lower than those in the laboratory air, with decreasing amplitude slightly larger than that at stress ratio R is 0.5 and 0.06.
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    Preparation and Characterization of Functionalized Graphene Oxide Nanoribbons/EVA Composite Films
    ZHENG Yu-ying
    2015, 43 (2): 96-102.   DOI: 10.11868/j.issn.1001-4381.2015.02.016
    Abstract ( 1643 ( PDF (3940KB)( 584 Citation
    Graphene oxide nanoribbons(GONRs) were prepared through oxidative longitudinal unzipping of multiwalled carbon nanotubes, and then modified by silane coupling agent, KH-570. The functionalized GONRs(K-GONRs)/EVA composite films were subsequently obtained by solution coating method on a coating machine. Structures and properties of the K-GONRs/EVA composite films were characterized by FTIR, XRD, XPS, TEM, FE-SEM, oxygen transmission rate tester and electronic universal testing machine. The results show that the thin banded K-GONRs with interlayer spacing about 0.970nm are successfully prepared, and there is an increasing in interlayer distance about 0.095nm for K-GONRs when compared with original GONRs. Meanwhile, the prepared K-GONRs is neat and with uniform shape and low defect,dispersed evenly in EVA matrix. Comparing with the pure EVA films, when the mass fraction of K-GONRs is 1%, the oxygen transmission rate of K-GONRs/EVA composite films is reduced by 54.5% and the tensile strength is increased by 89.3%.The barrier property and mechanical properties of EVA is obviously improved.
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    Progress in Preparation and Application of One-dimensional Nano Zinc Oxide
    BAO Yan, ZHANG Yong-hui, MA Jian-zhong, YANG Yong-qiang
    2015, 43 (2): 103-112.   DOI: 10.11868/j.issn.1001-4381.2015.02.017
    Abstract ( 1155 ( PDF (1599KB)( 474 Citation
    The preparation of one-dimensional nano ZnO consisting of vapor phase method, liquid phase method and template method was reviewed. Then the considerable attention was focused on the applications of one-dimensional nano ZnO in solar cell, sensors, multi-functional textiles, and photocatalytic degradation of organic matters, etc. Also, the problems in the preparation of one-dimensional nano ZnO were pointed out and its subsequent development was prospected.
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