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      20 December 2011, Volume 0 Issue 12 Previous Issue    Next Issue
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    Microstructures and Properties of DD3 Single Crystal Alloy Joints with Different Orientation
    LI Xiao-hong,ZHONG Qun-peng,CAO Chun-xiao,CHEN Bo1,MAO Wei
    2011, 0 (12): 1-5.  
    Abstract ( 709 ( PDF (1349KB)( 389 Citation
    The DD3 single crystal alloy specimens with the orientation combination of 0°+30°and 0°+60° were TLP diffusion bonded with D1F amorphous foil interlayer alloy. The effect of the crystal orientation between the two bonded single crystal alloy specimens on the microstructure and property of the joint was investigated. The results showed that, in the middle part of the joint bonded by two specimens with different crystal orientations, there existed a boundary composed of γ′phases in the form of large block, which was vertical to the applied stress and so became the weak part of the joint. As a consequence, the stressrupture property of the joint was below to 40% of that of the base material, and all of the test specimens fracture at the bonding seam. However, using the same interlayer alloy and the same bonding parameters, the joint formed by two specimens with the same crystal orientation exhibited homogeneous microstructures, and the stressrupture property of the corresponding joint was comparable to that of the base material. So in order to obtain the joints of high property, it should make the two bonded specimens with the same orientations as more as possible.
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    Experimental Study on Tension Behavior of Pure Titanium at High Strain Rates
    ZHANG Yin-xi,ZHANG Jun,HUANG Wen
    2011, 0 (12): 6-9.  
    Abstract ( 845 ( PDF (422KB)( 213 Citation
    Quasistatic and dynamic tension tests for pure titanium were performed using MTS809 testing system and rotating disk barbar tensile impact apparatus, respectively. The isothermal tension stressstrain curves at 0.001s-1 and 0.01s-1 and adiabatic tension stressstrain curves at 300s-1 and 1400s-1 were obtained. The dynamic tensile recovery test was carried out at the rate of 300s-1 and the isothermal stressstrain curve at the high strain rate was obtained. The results indicate that there exists the strain hardening,strainrate strengthening and adiabatic temperaturerise softening phenomenon in the tesion behavior of pure titanium. A modified KHL model  can describe and characterize the tensile behavior of titanium at different strain rates including high strain rates. The simulated results agree well with the experimental data.
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    Transformation Characteristic of Slowly Continuous Cooling Bainite and Effect of Alloy Elements in Microstructures
    ZHOU Hongbao,CAI Qingwu,WU Huibin,ZHANG Jie,CHEN Yulai
    2011, 0 (12): 10-15.  
    Abstract ( 765 ( PDF (1361KB)( 326 Citation
    Dilatometric tests were performed on the dilatometer under different cooling rates for the steels and the microstructures were observed. The point analysis of main elements was analyzed with the EMPA. The elements of Mo and Si were important for controlling grain transformation of the pearlite and granular bainite. When cooling rate at≤0.015℃/s, the variation of the microstructures was more complicated. The pearlite could be observed in the cooling slowly, the elements were heterogeneous distribution. The bainites were not the single microstructures, the morphology of bainites were lamellar and disordered granular. The pearlites presented at disordered granular area mainly.
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    Character of Stressinduced Twodimensional Low Intensity Field on Precut Notch Zone
    DONG Li-hong,XU Bin-shi,WANG Hui-peng,DONG Shi-yun
    2011, 0 (12): 16-19.  
    Abstract ( 642 ( PDF (457KB)( 239 Citation
    In order to investigate the signal character of twodimensional low intensity field, sheet specimens of 45CrNiMoVA steel were made. Axial stresses were applied to the specimens on a MTS 810 hydraulic servo machine, and an EMS2003 metal magnetic memory apparatus and an RM1 metal magnetic memory apparatus were used to collect horizontal component Hp(x) signals and normal component Hp(y) signals. The variations of the twodimensional low intensity field signals in the elastic deformation stage were analyzed. The results showed that Hp(x) signal curves presented a character of magnetic positive peak, while Hp(y) signal curves presented abnormal magnetic wave crest and hollow under the effect of applied tensile stress. There were linear relationships between the peak values, horizontal baseline mean values of Hp(x) signal curves and the applied tensile stress respectively,in the same way there existed linear relationships between the peaktopeak value, the peaktopeak slope coefficient of Hp(y) signal curves and the applied tensile stress respectively.
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    Adsorption Characteristics of Crystal Violet Dye by Different Types of Hydrogels
    ZHANG Qing-song,PENG Zhe,ZHAO Yi-ping,CHEN Li,MA Jing
    2011, 0 (12): 20-24.  
    Abstract ( 787 ( PDF (781KB)( 675 Citation
    The four types of hydrogels using acrylamide(AM) and isopropylacrylamide(NIPAM) as monomer, methylenebisacrylamide (MBA) and inorganic nanoclay lithium magnesium silicate hydrate (LMSH) as chemical and physical crosslinker, respectively, were prepared by freeradical polymerization in aqueous solution. The results show that, comparing with hydrogels crosslinked by MBA, the polyAM and polyNIPAM hydrogels using LMSH as physical crosslinking agent presents higher swelling ratios and lots of pore. The adsorption amount of crystal violet (CV) on polyAM and polyNIPAM hydrogels increases 58 times. In terms of adsorption and using effect, polyNIPAM hydrogel crosslinked by LMSH is the best choice for removing CV dye.
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    Experimental Study on Natural Ageing Character of T300/Epoxy Composite Under Marine Environmental Load
    ZHANG Ying-jun,ZHU Xi,MEI Zhi-yuan,LI Hua-dong
    2011, 0 (12): 25-28.  
    Abstract ( 726 ( PDF (404KB)( 383 Citation
    The natural cycle ageing which contained marinating in seawater and insolating was used to simulate and determine the durability of T300/epoxy composite made by the hand layup technics under marine environmental load. Natural ageing character of T300/epoxy samples was studied by changes in mass gain and mechanical property including tensile strength, tensile modulus, inplane shear strength and compression strength. The results show that after 140 days natural cycle ageing in Wuhan and Sanya, the mass gain increases with increasing time and the attenuation trend of mechanical properties is uniform. The ageing character of tensile modulus is inconspicuous. Tensile strength changes small, but inplane shear strength and compression strength have great attenuation extent. The residual strength of the samples in dryness state is stronger than that in wetness state.
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    Predictions of SN Curve and Residual Life of Welded Joints by Quantitative Thermographic Method
    FAN Jun-ling,GUO Xing-lin,ZHAO Yan-guang,WU Cheng-wei
    2011, 0 (12): 29-33.  
    Abstract ( 646 ( PDF (449KB)( 436 Citation
    With the specific nominal mean stress, considering the real operating situations of welded joints, the model for fast assessing the fatigue parameters and the residual fatigue life, was established by the infrared thermographic technique, realizing the fatigue performance evaluation of inhomogeneous welded joints using quantitative thermographic method. The damage evolution status was qualitatively analyzed by monitoring the hotspot variation on the welded joint surface. The results show that limitations of the traditional method are avoided, and that fatigue behavior parameters of inhomogeneous welded joints can be determined fast and accurately by quantitative thermographic method. Moreover, it is proved to be an effective way for health detection resorting to the hotspot variation detected realtimely during the fatigue process.
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    Preparation of Nanometer ZnO-CeO2 Composites and Its Absorption Properties
    LU Yin-mei,LI Li-hua,ZHANG Jin-sheng,LI Xiu-ping
    2011, 0 (12): 34-37.  
    Abstract ( 656 ( PDF (481KB)( 370 Citation
    The ZnO-CeO2 nanocomposite particles were prepared by heterogeneous method. The effects of different ratios of reactants, reactive temperature and pH on its absorption capability in UV ray region were investigated. Optimal preparation conditions were obtained. The ZnO-CeO2 samples were characterized by FTIR , XRD and TEM. The results indicated that the prepared composite nanoparticles were ZnO and CeO2, and the average size of the ZnO-CeO2  sample was about 15nm; The UV absorption capability was investigated by UV-Vis. There was a broad peak between 245nm and 400nm in UV ray region. Its absorbing boundary extended to 400nm. The composite particle had a prosperous applied future as UVabsorbing material.
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    Effect of TDI Modifying on Density and Mechanical Property of Ramie Fiber
    YANG Min-ge,WANG Qiong,WANG Jun-bo,HE Xin-hai,FU Chong,ZHAO Xue-man,QIN Hui
    2011, 0 (12): 38-41.  
    Abstract ( 858 ( PDF (425KB)( 329 Citation
    The density and mechanical property of ramie fiber and yarn which were treated by alkali and grafted by TDI on the optimal reaction conditions were studied. The molecular structure and crystal structure of ramie fiber were analyzed by IR and XRD. The results showed that, the density of ramie fiber and yarn which were treated by alkali and grafted by TDI was increased;the tensile strength of ramie fiber and yarn was decreased significantly. The tensile strength of ramie fiber treated by alkali declined 26.29%, and of the one grafted by TDI declined 29.13%(ultrasonic) and 22.67%(no ultrasonic). The tensile strength of ramie yarn treated by alkali  declined 39.04%, and of the one grafted by TDI declined 35.51%.
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    Wear Resistance and Microstructural Correlation for Amorphous Electroless NiWP Coatings Crystallized by Laser
    LIU Hong,GUO Rong-xin,BIAN Jian-sheng,ZHONG Hao,GONG Fang,LI Tai-zong
    2011, 0 (12): 42-47.  
    Abstract ( 730 ( PDF (932KB)( 614 Citation
    The microstructural characteristics of the amorphous electroless Ni-W-P coatings before and after laser crystallization were evaluated by a quantitative XRD method. Wear behaviour of the coatings were investigated by means of measurement of microhardness, wear test and optical microscope and SEM observation. The results indicate that crystalline reaction of Ni3P phase occurs at different scanning velocities. The  crystallization degree  of the coating increases with the decreasing  scanning velocity, but there is an incomplete crystallization for all coatings. At the scanning velocity of 7mm/s, the crystallization  degree  is 73.0%. The size of precipitated Ni3P is larger than Ni at the scanning velocity (10mm/s) of critical precipitation of Ni3P phase. The evolution of magnitude of both phases is opposite while the scanning velocity decreases. The sizes of both phases are in the range of nanoscale during the process of laser crystallization. Microhardness and wear resistance of the coating before and after laser crystallization are affected by the   crystallization degree, relative proportions of Ni and Ni3P phases as well as grain sizes. Adhesive wear dominates at 7mm/s, and abrasive wear is the major form of the coating at 8mm/s. The wear resistance of the coating can be improved with fitting  crystallization degree and suitable sizes of both phases.
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    Microstructure Analysis of Ni-SiC Nanocomposite Coating by Electrodeposition
    WU Hua,CHEN Tao,WANG Qing-hui
    2011, 0 (12): 48-52.  
    Abstract ( 812 ( PDF (679KB)( 370 Citation
    The Ni-SiC nanocomposite coatings were electrodeposited on copper substrate aided with ultrasonic. The effects of ultrasonic and the arrangement way of electrodes on the microstructure and properties of the composite coatings were discussed. The results indicated that the composite coatings were significantly refined by ultrasonic and secondary particles,the microhardness increased to HV760,and diffraction crystal plane of nickel (200) and (220) was varied, therefore, preferred orientation was inhibited in the process of grain growth. Compared to that the electrodes were placed in vertical, the thickness of the coating was 12.0μm and microhardness was HV343. This was attributed to the sedimentation of secondary particles covered cathode surface and reduced the deposition of nickel,when the electrodes were placed in horizon.
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    Study of Degradation Process and Water Diffusion Coefficient of Heavyduty Coatings in Seawater
    ZHU Cheng-fei,XIE Rui,XUE Jin-hua
    2011, 0 (12): 53-57.  
    Abstract ( 818 ( PDF (760KB)( 351 Citation
     The degradation process of heavy-duty coatings system composed of epoxy zinc rich primer, micaceous iron oxide intermediate, and chlorinated rubber top coatings in seawater was studied by the electrochemical impedance spectroscopy (EIS). The evolution of coatings capacitance was investigated to illuminate the water diffusion process and coefficient during coatings aging process. The results showed that the degradation process of the heavyduty coatings in seawater could be described in the two typical stages. The coating resistance decreased linearly at a rate of 1.9×107Ω·h-1 and 8381Ω·h-1 before and after 120h respectively. The lnCc-t1/2 curve for heavyduty coatings indicated that the coating capacitance presented two typical stages as the immersion time increased, the coating capacitance increased rapidly in the beginning time of immersion (0-30h), and then tended to be a slow growth stage after 30h. According to the linear part of ln Cc-t1/2 in the early immersion period, the water diffusion coefficient D was obtained and the value was 2.9076×10-9cm2·s-1.
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    Effects of Laser Scanning Conditions on Metallic Micro/Nanostructures in Multiphoton Nanofabrication
    JIN Wei,DONG Xian-zi,ZHAO Zhen-sheng,DUAN Xuan-ming
    2011, 0 (12): 58-62.  
    Abstract ( 652 ( PDF (666KB)( 276 Citation
    The influences of laser scanning conditions on the silver micro/nanostructures in multiphoton photoreduction of metallic micro/nanostructures and morphology using femtosecond laser were investigated. The results indicated that increasing the distance between scanning points (d) could make the width of lines become smaller and extending the exposure of time (t) could make the lines broadening. Furthermore, the increasing of scanning times (N) led to the formation of large silver particles and lumps on the structures due to the fusion of silver nanoparticles which on the surface of metallic micro/nanostructures.
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    Effects of Powder Hotpressing Process on Mechanical Properties of WCP/2024Al Composites
    LIANG Qiu-shi,MAO Chang-hui,YANG Jian
    2011, 0 (12): 63-67.  
    Abstract ( 559 ( PDF (869KB)( 330 Citation
    2024 aluminum alloy matrix composites reinforced with tungsten carbide particle (WCp/2024Al) were fabricated by vacuum hotpressing method. The effect of the forming temperature and WC particle size on the mechanical properties of the WCp/2024Al composites were carried by XRD, SEM and tensile testing. The results show that the forming temperature is one of the key factors that control the interfacial reaction of the WCp/2024Al composite. The products of the interfacial reaction lead to the strength and plasticity of the WCp/2024Al composite decline. The effects of WC particle size on the plasticity are  more than that effects on the tensile strength of the WCp/2024Al composites. The elongation of the composites increases with the increasing of WC particle size.
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    Effect of Friction Stir Welding on Microstructures and Mechanical Properties of Mg-Gd-Y-Zr Alloy
    BAO Zi-cheng,XU Li,DENG Yun-lai
    2011, 0 (12): 68-72.  
    Abstract ( 571 ( PDF (764KB)( 345 Citation
    Microstructures and mechanical properties of Mg-Gd-Y-Zr alloy slices as castT6 were studied after friction stir welding (FSW). The results showed that the weld nugget zone (WNZ), where the microstructures were consisted of refined and equiaxed grains by dynamic recrystallization, had the highest hardness. The thermo-mechanically affected zone (TMAZ), where the matrix grains had the characteristic of hotdeformation, and the second phases particles were coarsened or dissolved, had the higher hardness. The heat affected zone (HAZ), where the grain size was equal to the base metal, and the second phases particles became coarse, had the lower hardness than that of the base metal. During the present experimental condition, the ultimatetensilestrength of the sample perpendicularly cut to the welding line reached as much as 0.91 of the one of the base metal, and the elongation was greatly improved. The fracture analysis by SEM showed that the fracture mode of the joint was ductile.
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    Reaction Mechanism in Self-assembly Growth Formation of Mg-Mg2Si-MgO Composites
    JIN Ying,LANG Jing,CHEN Xi,ZHU Cong-xu,MA Nan-gang
    2011, 0 (12): 73-77.  
    Abstract ( 707 ( PDF (664KB)( 391 Citation
    With pure Mg and SiO2 powders as raw materials, an Mgbased metal matrix composite reinforced by MgO ceramic and Mg2Si intermetallic was formed through selfassembly growth method. The differential thermal analysis (DTA) was performed on the samples and it was revealed that the insitu reaction between Mg and SiO2 took place from 510℃ to 600℃. As a result of reaction, the MgO was formed, and the reduced Si continually reacted with excess Mg, forming Mg2Si. The observation of scanning electron micrograph and energy dispersive spectrometry indicated that, in the sample made by ultrasonic assisted stirring, the insitu formed MgO covered the Mg2Si intermetallic as a compact aggregate layer which had a strong bonding strength with the matrix. What’s more,the Vickers hardness tests showed that the Vickers hardness of ultrasonic assisted stirring sample was 40 percent higher than that of the sample made by generally stirring. The reaction mechanism between Mg and SiO2 was concretely discussed.
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    Preparation of EP/ZnO Composites with Needle Nano-ZnO and Its Mechanical Properties
    ZHANG Rong-liang,LIU Ya-shu,JIN Yun-xue
    2011, 0 (12): 78-82.  
    Abstract ( 540 ( PDF (640KB)( 277 Citation
    Effects of the needle nanoZnO which was made from hot galvanizing slag on the mechanical properties of the EP/ZnO composites were investigated. The results showed that EP/ZnO composites prepared by nanoZnO with spatial structure were better than that prepared by normal ZnO in mechanical properties. When the mass fraction of nanoZnO reached 4%, the mechanical properties of the composites were improved prominently, the impact strength increased 46.9%, the tensile strength increased 20.9%, the bending strength increased 13.3%, respectively.
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    Weld Formation Stability and Force in Variable Polarity Plasma Arc Keyhole Welding
    HAN Yong-quan,GUO Long,CHEN Shu-jun,DU Mao-hua ,WU Yong-jun
    2011, 0 (12): 83-86.  
    Abstract ( 629 ( PDF (499KB)( 306 Citation
    Using YB00501 pressure transmitter  the plasma arc force in positive polarity was greater than that in reverse polarity was measured.The thermal and force models on aluminum alloy variable polarity plasma arc (VPPA) keyhole molten pool were built. The stability of keyhole molten pool and the forming mechanism of weld under the action of thermal and force in asymmetric positive and reverse polarity plasma arc were analyzed. By further analysis of aluminum alloy variable polarity plasma arc mechanical and thermal characteristics, the key welding influence factors on welding current and plasma air flow were mastered. According to the keyhole welding process testing, the reasonably selected positive and reverse polarity current amplitude and plasma air flow which keep thermal and force balance during  keyhole welding process provided theoretical support for getting stable technique parameters in aluminum alloy variable polarity plasma arc welding.
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    Research Progress of Processing Aids for High Energetic Solid Propellants
    CHEN Yu,LIU Yun-fei,FAN Xi-ping,YANG Wei,YAO Wei-shang,TAN Hui-min
    2011, 0 (12): 87-90.  
    Abstract ( 562 ( PDF (250KB)( 538 Citation
    The research progress of the aids for the improvement of processing properties in high energetic solid propellants was summarized. Research and application of the processing aids were introduced according to the method to improve the processing performance of the propellant slurry, such as diluting the slurry, extending of the pot life, improvement the fluidity of the slurry, etc. The aids which could improve the fluidity of the particles and the mechanical properties of the propellant at the same time were much reported in recent years and were introduced emphatically. Some views on the further study of the multifunctional aids for high energetic solid propellants were presented.
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    Review of Preparation of Carboncoated Metal Nanoparticle by Arc Discharge Method
    LIU Tong-gang,ZOU Xue-zhuang,QIAN Zi-hang,WU Jian
    2011, 0 (12): 91-96.  
    Abstract ( 490 ( PDF (767KB)( 346 Citation
    The metal nanocrystals in carboncoated particle could be protected from the environment and still retain their intrinsic properties, which has received considerable attention in recent years for both its scientific and technological implications. The working principle of preparing carboncoated metal nanoparticles by arc discharge method was introduced. The research and development of the preparation method were briefly reviewed. The reaction path of metal and carbon, the types of the result product, and the formation mechanism of the carbon encapsulation were discussed.
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