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      20 March 2015, Volume 43 Issue 3 Previous Issue    Next Issue
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    Preparation and High-temperature Sintering Mechanism of ZrB2 Ceramic Composite Coatings for C/C-SiC Composites
    ZHANG Xiang, CHEN Zhao-ke, XIONG Xiang
    2015, 43 (3): 1-6.   DOI: 10.11868/j.issn.1001-4381.2015.03.001
    Abstract ( 869 ( PDF (3495KB)( 364 Citation
    The anti-oxidation ZrB2 ceramic composite coatings were prepared on C/C-SiC composites and C/C composites by means of slurry painting. The compositions and microstructures of the composites were examined by EDS analysis and SEM. The high-temperature sintering mechanism of ZrB2 ceramic composite coatings was discussed by comparing coating on C/C-SiC composites and C/C composites. The results show that silicon overflows from the C/C-SiC matrix during the sintering, which causes the mass loss of samples at high temperature. The silicon coming from matrix penetrates into ceramic coating, in which ZrB2 phase is dispersive distribution and silicon acts as the main binding phase. Silicon effectively promotes the combination of interface between coating and matrix. Based on the pretreatment of substrates and the method of low-temperature vacuum degumming and ordinary pressure sinter, a flawless ZrB2 ceramic composite coating is prepared, which has compact structure and tightly bounds with matrix.
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    Transformation of Ti-microalloyed TRIP Steel During Continuous Cooling
    YI Hai-long, XU Wei, LONG Lei-zhou, LIU Zhen-yu
    2015, 43 (3): 7-11.   DOI: 10.11868/j.issn.1001-4381.2015.03.002
    Abstract ( 840 ( PDF (4528KB)( 315 Citation
    The transformation behavior of a Ti-bearing microalloyed steel during continuous cooling at different start cooling temperatures was investigated by means of Formastor-FII phase transformation testing instrument. The continuous cooling transformation (CCT) curves were established, and the transformation behaviors of ferrite, bainite and martensite were analyzed. The results show that the ferrite, bainite and martensite are obtained successively with the increasing of cooling rate, and the bainite and martensite can be obtained in a wide range of cooling rate, and the martensite transformation start temperature (Ms) is about 450℃. The ferrite and bainite transformation start temperature decreases with the decreasing of start cooling temperature or increasing of cooling rate, so the ferrite and bainite phase transformation is inhibited. The microstructure of the steel transforms from ferrite plus granular bainite, lath bainite plus lath martensite and then to lath martensite successively with the increasing of cooling rate; when the cooling rate is low, the ferrite is composed intragranular ferrite and grain boundary ferrite, and the intragranular ferrite nucleat on complex oxide and sulfide.
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    Jet Morphology and Microstructure of Liquid Stream/ Atomization Plasma Spraying Based on YSZ Suspension
    FU You-heng, ZHANG Hai-ou, RUI Dao-man, WANG Gui-lan
    2015, 43 (3): 12-17.   DOI: 10.11868/j.issn.1001-4381.2015.03.003
    Abstract ( 995 ( PDF (2017KB)( 299 Citation
    8% (mole fraction)YSZ powder (d50=700nm) was used for suspension. A comparative study was conducted on the influence of different injection pressure and plasma power on the plasma jet morphologic characteristic with liquid stream/atomization injection. The microstructures of prepared coating was characterized by SEM method. The results show that more compact layers are obtained with atomization injection compared with liquid stream injection. As the spraying distance increases, more semi-melted particles are observed for both injection methods, which are beneficial for forming pore structure. Finely structured YSZ layers with 30μm thickness and 1.5% porosity are fabricated by atomization injection, which can be used as electrolyte layer of solid oxide fuel cell.
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    Study on Characteristics in TIG Welded Joint of Mg/Al Dissimilar Materials
    LIU Zheng-jun, GONG Ying, SU Yun-hai
    2015, 43 (3): 18-22.   DOI: 10.11868/j.issn.1001-4381.2015.03.004
    Abstract ( 994 ( PDF (3057KB)( 352 Citation
    TIG welding was carried out to weld aluminum and magnesium by using aluminum and zinc wires, respectively. The microstructures and properties were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and microhardness tester. The result shows that an obvious transition region with the width of about 300μm is clearly visible at Mg side while using aluminum wire. Besides, the interdiffusion between magnesium and aluminum results in the presence of fragile Mg17Al12 and Al3Mg2 intermetallics in the transition region, which makes the interface of the welded joint easy to fracture. Whereas, the interface between magnesium and zinc is clear and a solid solution layer with width of about 2μm is generated in the transition region between zinc and aluminum while using zinc wire. The existence of zinc prevents the interdiffusion between magnesium and aluminum and decreases the thickness of the transition region effectively, which restrains the formation of intermetallics.
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    Effect of Extruded Temperature on Microstructure and Mechanical Properties of Mg-2Zn-Mn-0.5Nd Alloy
    PENG Jian, PENG Yi, HAN Wei, PAN Fu-sheng
    2015, 43 (3): 23-27.   DOI: 10.11868/j.issn.1001-4381.2015.03.005
    Abstract ( 763 ( PDF (4019KB)( 226 Citation
    The effects and the action mechanism of extruded temperature on microstructure and mechanical properties of as-extruded Mg-2Zn-Mn-0.5Nd alloy were investigated. The result shows that when the extruded temperature changes from 340℃ to 420℃, the room temperature elongation raises from 14% to 26%, meanwhile the strength obviously decreases; When the extruded temperature changes from 340℃ to 260℃, the room temperature elongation can also be increased from 14% to 19%, but ultimate tension strength (UTS) and yield strength (YS) have no obvious decrease. The analysis shows that the grain size and the texture intensity of the alloy are the joint factors to decide the mechanical properties of the as-extruded Mg-2Zn-Mn-0.5Nd alloy.
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    Stress Corrosion Cracking Behavior of 16Mn Steel and Heat-affected Zone in Alkaline Sulfide with Different pH Value
    HAO Wen-kui, LIU Zhi-yong, MA Yan, DU Cui-wei, LI Xiao-gang, HU Shan-shan
    2015, 43 (3): 28-34.   DOI: 10.11868/j.issn.1001-4381.2015.03.006
    Abstract ( 774 ( PDF (4040KB)( 339 Citation
    The behavior and mechanism of stress corrosion cracking (SCC) of 16Mn steel and its heat-affected zone (HAZ) in alkaline sulfide and Cl- solution medium with different pH value was investigated by U-bent specimen immersing test and electrochemical technology. Results show that the original microstructure, the coarse grain structure (air cooling structure) and the hardening microstructure (quenching structure) exhibit a similar passivation state in alkaline sulfide solution with pH=11.8, passive current density gradually decreases; As pH value decreases, anodic process of original structure and coarse grain structure gradually change from the passivation state to the activation state. The SCC susceptibility of the hardening structure, coarse grain structure and original structure of heat-affected zone(HAZ) in alkaline sulfide environment gradually decreases, the hardening structure exhibits obvious SCC feature. With the decrease of pH, SCC cracks tend to change from intergranular cracks to transgranular and intergranular combined cracks and the width of the cracks increases.
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    Structure and Photoelectric Properties of Sb-doped ZnTe Thin Films
    ZOU Kai, LI Rong-ping, LIU Yong-sheng, TIAN Lei, FENG Song
    2015, 43 (3): 35-41.   DOI: 10.11868/j.issn.1001-4381.2015.03.007
    Abstract ( 966 ( PDF (2054KB)( 376 Citation
    ZnTe and Sb-ZnTe polycrystalline thin films were prepared by vacuum evaporation on glass substrates and annealed in nitrogen environment. By using XRD, SEM, UV-VIS spectrophotometer and Hall effect measurements, the crystal structure, surface morphology, elemental composition, optical and electrical properties of the thin films were characterized, respectively, and the effects of Sb-doping amounts and heat treatment on the performance of the films were studied. The results show that pure ZnTe film is the cubic structure and preferentially orients in the (111) direction and its conductive type is P type. Sb-doping does not change the structure and conductive type of the films, but the intensity of diffraction peaks is lower than that of pure ZnTe films; the concentration of Sb directly affects the form of Sb in the ZnTe. Sb doping inhibits the combination of Te and Zn, and leads to the increase of Te in the films. In addition, the optical transmittance and optical band gap of the films depend on the concentration of Sb and annealing temperature, and Sb-doping can also result in an obvious increasing of carrier concentration and reduce the resistivity, which significantly enhance the conductivity of the films.
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    Corrosion Resistance of Galvalume Coated Steel in Qingdao Seawater
    LIU Shuan, SUN Hu-yuan, SUN Li-juan, ZHANG Ning, CHEN Jian-min
    2015, 43 (3): 42-47.   DOI: 10.11868/j.issn.1001-4381.2015.03.008
    Abstract ( 821 ( PDF (2878KB)( 273 Citation
    The corrosion resistance of Galvalume coated steel in Qingdao seawater was investigated by polarization curves and EIS methods. The morphology of corrosion products absorbed on the coating was analyzed by scanning electron microscopy (SEM), the effects of temperature and dissolved O2 concentration on electrochemical corrosion behavior of Galvalume coated steel were studied in details. The results show that the protective corrosion product film absorbed on the coating is damaged and the anodic reaction is activated with the increase of temperature. The cathodic reaction is inhibited under low concentration of dissolved O2 and the corrosion resistance of the galvalume coating is improved.
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    Microstructure and Hydrogen Storage Properties of Nanostructured Mg-Al Alloy from Reactive Milling with Carbon as Milling Aid
    ZHANG Tong-huan, ZHOU Shi-xue, NIU Hai-li, XIAO Cheng-zhu, WANG Nai-fei
    2015, 43 (3): 48-53.   DOI: 10.11868/j.issn.1001-4381.2015.03.009
    Abstract ( 967 ( PDF (1825KB)( 321 Citation
    Nanostructured Mg-Al alloy hydrogen storage material was prepared with modified anthracite as milling aid by ball milling under hydrogen atmosphere. The crystal phase structure and dehydrogenation kinetics properties of the ball milled hydrogen absorbing materials and static re-hydrogenated materials were analyzed by SEM, XRD and TPD. The results show that the modified anthracite plays a good milling aid role, after 5.5 h of milling, the average particle size of Mg-Al alloy reaches to 74 nm; The Mg in the Mg-Al alloy transforms into β-MgH2 and γ-MgH2 after reaction ball milling, whose peak dehydrogenation temperature is lower than 300 ℃. Yet, after static re-hydrogenation, the MgH2 all exists in β-MgH2 which shows a 60% increase in crystal size, and the Mg17Al12 decomposes into elementary Mg and Al. The elementary Al decreases the dehydrogenation activation energy of hydrogen storage materials, where the hydrogen level of apparent activation energy of the ball milled hydrogen storage material and re-hydrogenated material is 107.3kJ/mol and 67.1kJ/mol, respectively, calculated according to the Kissinger equation.
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    Researches on Process and Microstructure of 2A12 and 2A11 Aluminum Ultrasonic Welds
    XIE Jun-feng, ZHU You-li, HUANG Yuan-lin, BAI Chang
    2015, 43 (3): 54-59.   DOI: 10.11868/j.issn.1001-4381.2015.03.010
    Abstract ( 907 ( PDF (4530KB)( 488 Citation
    Ultrasonic welding of 2A12-T3 and 2A11-O aluminum alloy was carried out and effects of ultrasonic welding parameters on the welded interface bonding were studied. The welded interface microstructure was investigated via scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). Results show that favorable welded interface bonding with a linear weld density approaching 100% is obtained at ultrasonic welding vibration amplitude of 30μm and welding duration of 0.2s. Argon shield shows influence on the linear weld density. When the vibration amplitude is 15m, argon shield can improve the linear weld density; when the vibration amplitude is 30m, argon shield has no obvious influence on the linear weld density. Ultrasonic welding bring about ripple or vortices plastic flow at the welded interface, with accompanying dynamic recovery and continuous dynamic recrystallization, which result in the welded interface microstructure consisting of dislocation tanglings, dislocation cells, sub-grains and fine grains.
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    Molecular Dynamics Simulations of Deformation Behaviors for Nanocrystalline Cu/Ni Films Under Different Strain Rates
    CHENG Cong, CHEN Shang-da, WU Yong-zhi, HUANG Hong-xiang
    2015, 43 (3): 60-66.   DOI: 10.11868/j.issn.1001-4381.2015.03.011
    Abstract ( 718 ( PDF (6133KB)( 365 Citation
    Molecular dynamics simulations are carried out to investigate the deformation behaviors and mechanical properties of nanocrystalline Cu/Ni films under conditions of tensile strain at different strain rates. The results indicate that the Cu/Ni films have higher yield strength and higher strain rate sensitivity(m)at the higher strain rate. The nucleation of voids in Cu/Ni multilayers' interface is observed at a strain rate of 108s-1, whereas spallation in nanocrystalline Cu films is appeared at a strain rate of 1010s-1.For the higher strain rate loading conditions, the FCC, HCP, and OTHER atomic groups are changed significantly both in Cu and Ni films. However, striking structural changes are found only in the Cu films under conditions of tensile strain at lower strain rate. The simulation results show that increasing strain rates are benefit to the formation of HCP structure, while if the strain rates exceed a certain value, the increasing disorder atomic groups may impede the growth of HCP atomic groups.
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    Microstructure and Corrosion Properties of Aluminum Matrix Composite Reinforced with Al-based Amorphous
    LIU Peng, LI Shi-kai, ZHANG Yuan-bin, LIU Yan
    2015, 43 (3): 67-71.   DOI: 10.11868/j.issn.1001-4381.2015.03.012
    Abstract ( 757 ( PDF (1929KB)( 262 Citation
    The microstructure and corrosion properties of a novel Al-based amorphous reinforced aluminum matrix composite fabricated by friction stir processing (FSP) were studied by scanning electron microscope(SEM), transmission electron microscope(TEM) and electrochemical corrosion test methods. The test results show that the composite exhibits the typical layered structure with a combination of the base metal and the amorphous strip via the FSP, and shows a large amount of nanosized ultrafine structure which are mainly composed of the α-Al and α-Al amorphous structure with Al-Cu-Mg series precipated phase existing in the composite. The tensile strength of composite is improved a lot compared with the base metal. The electrochemical corrosion behavior of the composite with amorphous strip is also improved compared with that without amorphous strip, but, in both cases, the corrosion bebaviour is lower than the base metal.
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    Preparation and Photocatalytic Properties of Magnetic Responsive TiO2/Graphene Nanocomposites
    ZHANG Ping, MO Zun-li, ZHANG Chun, HAN Li-juan, LI Zheng
    2015, 43 (3): 72-77.   DOI: 10.11868/j.issn.1001-4381.2015.03.013
    Abstract ( 947 ( PDF (1790KB)( 339 Citation
    A new type of magnetic responsive TiO2/graphene nanocomposites with response to external optical and magnetic fields was prepared by using emulsion intercalation hydrolysis method. Magnetic Fe3O4 nanoparticles were synthesized by hydrothermal method and dispersed in ethanol containing tetra-n-butyl titanate through ultrasonic processing to establish a tetra-n-butyl titanate micro-emulsion wrapping Fe3O4 nanoparticles. Then, the micro-emulsion was intercalated into graphene layers by vigorous stirring and a stable system was formed. Thereafter, the Fe3O4 and TiO2 nanoparticles were embedded into the layers of graphene through a controllable hydrolysis process. The morphology and structure of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The photocatalytic properties of the synthesized nanocomposites were evaluated by degrading methylene blue in simulated solar light. The magnetic responsive TiO2/graphene nanocomposites exhibit excellent photocatalytic performance, and can be used repeatedly after the magnetic separation. The removal rate of methylene blue still maintains more than 90% even after repeated use for 7 times.
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    Preparation and Property of Low Pressure Vacuum Nitriding Modified Layer on TC4 Titanium Alloy
    YANG Chuang, PENG Xiao-dong, LIU Jing, MA Ya-qin, WANG Hua
    2015, 43 (3): 78-82.   DOI: 10.11868/j.issn.1001-4381.2015.03.014
    Abstract ( 915 ( PDF (2211KB)( 360 Citation
    A modified layer with good bonding strength with substrate was prepared on the surface of TC4 titanium alloy by low pressure vacuum nitriding treatment. The microstructure of surface modified layer was analyzed by optical microscopy, X-ray diffractometry (XRD), scanning electron microscopy (SEM), the microhardness and wear resistance of the modified layer was measured. The results show that a surface nitrides modified layer composed of TiN and Ti2AlN can be obtained by low pressure vacuum nitriding treatment, the microstructure is uniform and compact, with fine nitride particles, the hardened layer has a good bonding strength with its substrate, the surface hardness is 1100-1200 HV, and the hardness in the core is 300-320 HV, the depth of the hardened layer can reach 60-70μm, the hardness gradient of nitrided layer is smooth, and it has superior wear resistance.
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    Research Progress on Visible Light Active Nitrogen Doped Nano-TiO2
    CAO Wen-bin, XU Jun-na, LIU Wen-xiu, SUN Peng, ZHANG Xin
    2015, 43 (3): 83-90.   DOI: 10.11868/j.issn.1001-4381.2015.03.015
    Abstract ( 1014 ( PDF (1492KB)( 451 Citation
    Nitrogen doped TiO2 has attracted much attention as nitrogen doping can widen its photo response range, realize its visible light response, improve the utilization of solar light energy and further increase its photocatalytic efficiency. The effect of nitrogen doping on the band structure in the TiO2 and the research progress on the preparation method of nitrogen doped TiO2 film and powder were reviewed. The current problems needed to be solved were summarized, and some thinking on the future development was also put forward.
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    Progress in Research on Preparation and Application of Graphene Composites
    YANG Wen-bin, ZHANG Li, LIU Jing-wei, LIU Huan-rui, TANG Bing-hua
    2015, 43 (3): 91-97.   DOI: 10.11868/j.issn.1001-4381.2015.03.016
    Abstract ( 2017 ( PDF (637KB)( 1933 Citation
    Graphene is a single atomic layer structure, which is the thinnest 2-D planar sheet composed of sp2-bonded carbon atoms. The special structure of graphene has excellent properties, such as photoelectric property, heat stability and mechanical properties. There has been increasing attention to preparation, property and application of graphene composites in recent years. In the paper, preparation methods of graphene composites is reviewed, such as graphene/polymer composites, graphene/metal (metal oxide) composites, and ternary composites of graphene. The advances in application of graphene composites are also reviewed, such as in lithium battery, supercapacitors, photovoltaic devices, sensor applications. Furthermore, the important research direction of graphene composites is pointed out.
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    Progress in Research on Environmental Corrosion-resistance of Structural Adhesive Bonding Automotive-body Metal Joint
    ZHENG Rui, LIN Jian-ping, WU Qian-qian, WU Yong-rong
    2015, 43 (3): 98-105.   DOI: 10.11868/j.issn.1001-4381.2015.03.017
    Abstract ( 975 ( PDF (1559KB)( 493 Citation
    Research status on the environmental corrosion resistance of adhesive bonding automotive body metal joint was summarized from the transfer law of corrosive medium when expose to environment, effect of environmental exposure on mechanical properties of adhesive bonding metal joint, the degradation mechanism and surface treatment technology of metal adherend. The developing trend of the study on the environmental corrosion resistance of metal bonding joint was discussed. The results show that the further research should focus on the diffusion law of corrosive medium in the interface of the adhesive bonding joint, the mechanism and law of the damage of electrochemical reaction on metal joint surface to the interface bonding performance, the electrochemical corrosion law in metal joint, and the effect of electrochemical reaction on bonding performance and the strength of joint.
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    State of Arts of the Dynamic Mechanical Behaviors of High Performance Polymer Composites in Typical Aerospace Environments
    GAO Yu, WANG Zhao, LU Chun, BAO Jian-wen, SONG En-peng, DONG Shang-li
    2015, 43 (3): 106-112.   DOI: 10.11868/j.issn.1001-4381.2015.03.018
    Abstract ( 941 ( PDF (789KB)( 432 Citation
    With the rapid increase of carbon fiber reinforced resin matrix composites used in aircraft structure, their application gradually extends from non-load-bearing components to load-bearing components. The dynamic mechanical problems of the composite structures that are subjected to fatigue, low velocity impact and high velocity impact have attracted broad attention from both domestic and foreign researchers. The interactions between typical aerospace environmental factors with carbon fiber reinforced resin matrix composites are summarized. The behaviors of the composites under fatigue loading, low velocity impact and high velocity impact was mainly discussed. The effect of coupling between environment damage and dynamic load on dynamic mechanical properties of carbon fiber reinforced resin matrix composites are described. The aim of this work is to provide beneficial reference for the application of polymer matrix composites in aerospace vehicles.
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