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      20 February 2014, Volume 0 Issue 2 Previous Issue    Next Issue
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    Preparation, Characterization and Microwave Absorbing Properties of Fe85Si9.6Al5.4 Alloys in the Low Frequency Range
    FENG Yong-bao, TANG Chuan-ming, QIU Tai
    2014, 0 (2): 1-6,12.   DOI: 10.3969/j.issn.1001-4381.2014.02.001
    Abstract ( 912 ( PDF (2599KB)( 531 Citation
    The Fe85Si9.6Al5.4 alloys were prepared by mechanical alloying (MA) method. The phase structure, morphology, soft magnetic properties of the Fe85Si9.6Al5.4 alloys, the electromagnetic and absorbing properties of the FeSiAl/paraffin absorbers were investigated with XRD, SEM, VSM and VNA. The results show that the crystalline structures of the FeSiAl alloys prepared by both one-step MA process and two-step MA process are disordered bcc-Fe (Si, Al) solid solutions. The shape of FeSiAl alloy prepared by the one-step MA process is irregular, while the FeSiAl alloy prepared by the two-step MA process is flake-shaped. The specific saturation magnetization and coercivity are similar to the FsSiAl alloys prepared by two methods.Compared with the irregular FeSiAl/paraffin absorber, the absorber filled with flaky FeSiAl alloys possesses the higher complex permittivity and permeability and presents lower reflectivity in the range of 0.5-5GHz. For the 2-5mm absorber filled with flaky FeSiAl alloys, the minimum reflectivity decreases and the matching frequency moves towards the lower frequency with the increase of the thickness. The absorption bandwidth of the 2mm absorber (RL≤-10dB) is 1.07GHz.
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    Synthesis and Photocatalytic Performance of Dendritic CdS Nanostructures by an Ionic Liquid-assisted Hydrothermal Route
    ZHAO Rong-xiang, LI Xiu-ping, XU Zhu-de
    2014, 0 (2): 7-12.   DOI: 10.3969/j.issn.1001-4381.2014.02.002
    Abstract ( 702 ( PDF (2241KB)( 336 Citation
    Dendritic cadmium sulfide were synthesized in aqueous solution of Ethylenediamine fluoborate-based ionic liquid(BF4) with cadmium chloride and thiourea as raw materials.The obtained products were characterized by X-ray diffraction, scanning electron microscopy, fluorescence spectroscopy.Optical properties of dendrites CdS and photocatalytic degradation of methyl orange were tested.The results show that the ionic liquid and reaction time play an important role in the formation of dendritic structures of cadmium sulfide. A possible growth mechanism on the formation of dendritic CdS was proposed. The experiment results of photocatalysis indicate that the as-prepared CdS nanostructures have high photocatalytic degradation rate for methyl orange under UV, and the photocatalytic degradation rate of methyl orange is up to 85% after 280 min degradation.
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    Finite Element Simulation of Quasi-static Indentation Tests on Foam Core Sandwich Composites
    XIE Zong-hong, LIU Hai-han, TIAN Jiang
    2014, 0 (2): 13-17.   DOI: 10.3969/j.issn.1001-4381.2014.02.003
    Abstract ( 1038 ( PDF (4245KB)( 293 Citation
    Quasi-static indentation (QSI) tests were performed on foam core sandwich composites, and the damage propagation behavior of foam core sandwich composites under quasi-static indentation force was obtained. The FEM model was built by using Ansys Parametric Design Language.The stiffness reduction method was used to simulate the failure process of the core during the loading process. A method of predicting the damage resistance of foam core sandwich composites subjected to quasi-static indentation was proposed. The FEM results were compared with the existing test data, and a good agreement has been obtained.
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    Effect of MSU-J and Organic Modification on Mechanical and Thermal Properties of PMMA Hybrid Material
    JIAO Jian, WU Guang-li, LIU Peng, CAI Yu
    2014, 0 (2): 18-23.   DOI: 10.3969/j.issn.1001-4381.2014.02.004
    Abstract ( 1205 ( PDF (2136KB)( 207 Citation
    Mesoporous silica/poly(methyl methacrylate) (PMMA) hybrid material with three dimensional network nano-structure was prepared via in situ polymerization of MMA. In these hybrid material, two kinds of mesoporous silica with wormhole framework structure, MSU-J and MSU-J-G modified by γ-(Methacryloyloxy) propyl trimethoxy silane (MAPTS) via post-grafting, were introduced as the inorganic filler. Morphologies, mechanical and thermal properties of these hybrid material were investigated. The results of the TEM and density of hybrid material show that the nano-porous channels of MSU-J and MSU-J-G are not destroyed in hybrid material, and about 90% channels are filled by PMMA. The mechanical properties of hybrid material exhibited optimum value when the mass fraction of MSU-J or MSU-J-G is 7%. The tensile strength and modulus are improved by 38.9%, 40.2% (containing MSU-J) and 46.7%, 39.5% (containing MSU-J-G) compared with the matrix. In the same time, the elongation at break and impact strength decrease slightly. The thermal decomposition temperature (Td) and glass transmission temperature (Tg) of hybrid material are also improved respectively. Generally, the better dispersion of MSU-J-G in the matrix compared to MSU-J induced more improved mechanical and thermal properties of MSU-J-G/PMMA compared to MSU-J/PMMA hybrid material.
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    Effects of Space Atomic Oxygen Irradiation on the Structure and Tribological Properties of Ni/MoS2-C Coating by Electricity Brush Plating
    LI Guo-lu, WANG Hai-dou, XU Bin-shi, MA Guo-zheng, ZHANG Sen
    2014, 0 (2): 24-28.   DOI: 10.3969/j.issn.1001-4381.2014.02.005
    Abstract ( 732 ( PDF (2822KB)( 250 Citation
    The effects of space atomic oxygen (AO) on the electricity Ni/MoS2-C lubricating coating by electricity brush plating were discussed.The microstructures, compositions and phase structures of the coating were analyzed by SEM, EDS, TEM and XRD. The tribological properties of the coating under different time of AO irradiation were tested by MSTS-1 ultra-functional attrition testing machine. The results show that the AO has an obvious oxidation corrosion effect on the coating and the content of MoO3 in the coating increases. Simultaneously, the friction coefficient is relatively low because of the existence of thin oxide film in the early stage of experiment. The structure of the coating surface is inhomogeneity due to the high speed impact of AO. In such a case, the cracks of coating surface increase and the density of the coating gets some degree of damage due to the variation of stresses caused by vacuum suction effect. However, the friction coefficient is reduced effectively because of the presence of thin oxide film. The energy of AO is not sufficient to completely destroy the tribological properties of Ni/MoS2-C coating.
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    Evolution Mechanism of Weld Nugget Zone of FSW Joint of Die Casting AZ91D Magnesium Alloy
    YOU Guo-qiang, ZHANG Jun-cheng, TAN Xia
    2014, 0 (2): 29-33.   DOI: 10.3969/j.issn.1001-4381.2014.02.006
    Abstract ( 791 ( PDF (2134KB)( 281 Citation
    Die casting plates of AZ91D magnesium alloy with thickness of 4mm, were welded by friction stir welding at the rotating speed of 1200r/min and the welding speed of 40mm/min.The weld joint with no defect can be obtained. The joint microstructures were observed by OM,SEM. The results show that the microstructures are distinctly different in weld nugget zone. The grains of crown zone at the top of weld nugget are uniform, coarse and highly dense recrystallized grains with an average grain size 15μm;the grains of the central ring area and bottom zone are relatively fine and recrystallized and less uniform than that of the crown zone. The microstructures of weld nugget are recrystallization grain.The grain nucleation model are similar to the discontinuous dynamic recrystallization mechanism.
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    Effect of Contact Stress on Rotating Bending Fretting Fatigue Life of Railway Axle Steel
    SONG Chuan, LIU Jian-hua, PENG Jin-fang, ZHANG Lin, ZHOU Yan, ZHU Min-hao
    2014, 0 (2): 34-38.   DOI: 10.3969/j.issn.1001-4381.2014.02.007
    Abstract ( 726 ( PDF (1985KB)( 264 Citation
    LZ50 railway axle steel were carried out to study the effects of contact stress on rotating bending fretting fatigue life under different press-fit contact stresses. Optical microscope (OM) and Scanning electron microscope (SEM) were used to analyze the press-fit fretting damage surfaces and fracture surfaces, respectively. The results show that the rotating bending fretting fatigue life of the LZ50 present a non-liner feature,decrease with the increase of contact stress firstly, and then increase. It is due to the combination of the complex multi-axial stress of sample, contact stress between contact interfaces, fretting frication stress and the interaction between fretting wear and fretting fatigue.
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    Microstructure Design and Elastic Property Analysis of Foam Material
    ZHANG Fu, LI Xu-dong
    2014, 0 (2): 39-44,50.   DOI: 10.3969/j.issn.1001-4381.2014.02.008
    Abstract ( 943 ( PDF (2589KB)( 243 Citation
    Two groups of real structure of foam material were fitted by using random packing of spheres, and the microstructures of anisotropic opened-cell foam and isotropic closed-cell foam microstructure base on Laguerre model were obtained. The VirtualTPS software was developed for foam microstructure simulation by integrating the programming of Laguerre algorithm and secondary development of commercial finite element software ABAQUS pre-processing. The effects of different coefficient variation of cell volume and relative density to elastic module of foam material in density range were discussed. The numerical analysis results show that the relative elastic modulus has small affect on the coefficient variation of cell volume and has exponential relationship with the relative density.
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    Sintering Densification of Al-Si Composite by Powder Metallurgy Method for Electronic Packaging
    YU Sheng-lin, XUE Song-bai, YIN Bang-yue, HUANG Wei
    2014, 0 (2): 45-50.   DOI: 10.3969/j.issn.1001-4381.2014.02.009
    Abstract ( 800 ( PDF (2427KB)( 259 Citation
    The sintering behaviour of Al-Si composite was studied by using powder metallurgy method. The results show that the relative sintering density decreases from 99.7% to 99.0% when the Si content in the Al-Si composite is from 40% to 60%. The particle size distribution of the powders used in the sintering of Al-Si composite has a slight effect on the sintering density. Furthermore, sintering density increases obviously with the increase of sintering temperature,indicating the optimum sintering temperature is between 550℃ and 600℃. With the increase of sintering pressure, the sintering density of Al-50Si composite increases remarkably.Because of the higher pressure, the plastic deformation amount of those spherical powders used in the sintering of Al-Si composite increases so that the gap between the two neighbored powders is shortened, which benefits to the improvement of the sintering density. However, the optimum sintering pressure is 60MPa, and the corresponding relative sintering density of Al-50Si composite is 99.3%.
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    The Finite Element Simulation of Tread Rubber Coextrusion
    WANG Guo-lin, LIU Gao-jun, WANG Lei, ZHANG Ling-xin
    2014, 0 (2): 51-54.   DOI: 10.3969/j.issn.1001-4381.2014.02.010
    Abstract ( 909 ( PDF (1482KB)( 301 Citation
    Based on coextrusion process of tire tread rubber, Phan-Thien and Tanner(PTT) constitutive equation and Navier slip equation were used to simulate the three-dimensional flow of the viscoelastic melt (TWS/FB) at the exit in tread rubber coextrusion process. The effects of different slip length was analyzed, the results show that viscosity difference is one of the main factors that cause the interface deflecting to the higher viscosity,when the inflow rates of two rubber melts are the same. The velocity field and shear rate distribution are reduced and uniform along with the proper increase of slip length. The die swell and the interface deflexion phenomenon will be reduced effectively.
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    Mechanical Properties of Porous Metal Materials and Their Dependence on Geometric Parameters
    ZHANG Xiao-wei, WANG Yan-li, CHEN Li, ZHANG Qing-ming
    2014, 0 (2): 55-59.   DOI: 10.3969/j.issn.1001-4381.2014.02.011
    Abstract ( 789 ( PDF (2089KB)( 323 Citation
    By means of material testing systems (MTS) and scanning electron microscope (SEM), the mechanical properties and microstructural characteristics of several porous copper foams were investigated. The results show that the compression behavior of these materials presents three typical stages, which are elastic stage, plateau stage and densification stage. Their mechanical properties depend on not only the relative density but also the pore size. Meanwhile,the dependence of mechanical properties on the pore size is mainly due to the structural anisotropy.
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    Effect of Antifoam Agent Dimethicone on the Performance of Polyurethane/SiC Composite
    XING Zhi-guo, HUANG Yan-fei, LYU Zhen-lin, ZHOU Yong-xin
    2014, 0 (2): 60-64.   DOI: 10.3969/j.issn.1001-4381.2014.02.012
    Abstract ( 829 ( PDF (2114KB)( 258 Citation
    Polyurethane/SiC composite was prepared with polyurethane colloid, and the effects of antifoam agent dimethicone (PMDS) on the cementation and wear erosion performance of polyurethane/SiC composite were studied. The results show that the antifoam agent can obviously improve the shear strength and tensile strength of the polyurethane SiC composite, but affect the flexural strength of the polyurethane /SiC composite slightly.The antifoam agent can remarkably improve the abrasion erosion wear performance of the polyurethane /SiC composite.
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    Influence of Water Content and Dependent Scattering on Radiation Properties of Aerogel
    DUAN Yuan-yuan, YU Hai-tong, WANG Xiao-dong, ZHAO Jun-jie
    2014, 0 (2): 65-69.   DOI: 10.3969/j.issn.1001-4381.2014.02.013
    Abstract ( 653 ( PDF (1364KB)( 286 Citation
    The coated sphere model of Mie's theory was used to calculate the extinction coefficients of aerogel containing water. Dependent scattering was taken into consideration with purpose of improving the results. Finally, the temperature-related radiative conductivity was calculated from the Rosseland average of extinction coefficients. The best prediction comes from independent scattering of coated sphere model, which offers more refined extinction coefficient calculation and slightly better prediction of radiative conductivity than the original Mie's theory. Existing dependent scattering theories help little to improve calculation.
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    Morphology and Properties of Dip-coated Silicon Dioxide Ceramic Films
    ZHOU Qi, WAN Wen-lu, ZHANG Chun-li, HE Chun-lin
    2014, 0 (2): 70-74.   DOI: 10.3969/j.issn.1001-4381.2014.02.014
    Abstract ( 778 ( PDF (1703KB)( 317 Citation
    A dipping technology was used to prepare thin silica ceramic film on a composite nickel-plated A3 iron substrate.The microstructures of ceramic membrane was observed by SEM.The corrosion resistance properties and the wear-resistance properties were performed by electronical impedance spectroscopy and the flat surface abrasion machine,respectively.The results show that the surface morphology of silicon oxide ceramic coating sintered at 500℃ is similar to micro-crack chromium and the surface morphology of those sintered at 400℃ is similar to micro-porous chrome.Ceramic coatings are amorphous SiO2 after sintered at 400℃ and 500℃. The corrosion process of silica sol gel film with high impedance in 3.5% (mass fraction) NaCl solution is controlled by diffusion procedure, which can obviously inhibit the corrosion of nickel deposit on A3 iron substrate, and that with low impedance is controlled by electrochemical step. The wear-resistance of films after dip-coating is significantly better than that of eletroplating nickel. Silica sol-gel coating can reduce its porosity. The wear-resistance of composited plating nickel on iron substrate are improved by the silica sol-gel coatings.
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    Preparation and Characterization of SiC/C Nano-composites
    GAN Xiao-rong, XUE Fang-hong, HUANG Hao, DONG Xing-long, WANG Xiao-yun, YU Hong-tao, LIU Yan-ming, QUAN Xie
    2014, 0 (2): 75-80,86.   DOI: 10.3969/j.issn.1001-4381.2014.02.015
    Abstract ( 886 ( PDF (1789KB)( 300 Citation
    Using micrometer-sized graphite powder and Si powder as raw material, SiC/C nano-composites were in-situ synthesized by direct current arc-discharge plasma method with H2 as reactive gas under the Ar atmosphere. The components of the obtained product were characterized by XRD, Raman and IR. The morphology and microstructure of the sample were observed by SEM and TEM. Optical absorption properties and photocatalytic ability in decomposition of methylene blue were tested respectively by UV-visible reflection spectrometer and UV-VIS spectrophotometer. The results indicate that the as-synthesized products are globular composites of SiC/C consisting of β-SiC as main phase and a small amount of C;The average diameter of the composite is about 0.5-1μm, of which the thickness of C shell is 60 nm and the inner is SiC particles with average diameter of 50 nm.The band gap of the as-formed composites is 2.35eV and which exhibit high electron mobility and certain photocatalytic ability.
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    A Comparative Study of Two High-temperature Constitutive Models of 38MnVS6 Microalloyed Forging Steel
    WANG Jin, CHU Zhong, ZHANG Qi
    2014, 0 (2): 81-86.   DOI: 10.3969/j.issn.1001-4381.2014.02.016
    Abstract ( 1182 ( PDF (1940KB)( 353 Citation
    Isothermal hot compression tests of 38MnVS6 steel were performed to obtain the flow stress curves on a Gleeble-1500 thermo-mechanical simulator at temperature of 950-1200℃ and strain rate range of 0.1-10s-1. Based on the experimental results, Arrhenius-type and artificial neural network constitutive models were established respectively. Standard statistical parameters, such as correlation coefficient and average absolute relative error, were employed to quantify predictability of the two models. The results show that the artificial neural network constitutive model has high accuracy, and is more suitable for predicting the high-temperature flow stress of the steel.
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    The Influence of High Pressure Thermal Hydrogen Charging on Very High Cycle Fatigue Behavior of SUJ2 Bearing Steel
    LI Yong-de, XU Na, GUO Wei-min, WU Xiao-feng, SHI Jun-bo, LIU Shu-wei
    2014, 0 (2): 87-93,98.   DOI: 10.3969/j.issn.1001-4381.2014.02.017
    Abstract ( 680 ( PDF (3550KB)( 242 Citation
    The very high cycle fatigue (VHCF) behavior of JIS-SUJ2 bearing steel and the effects of high pressure thermal hydrogen charging (HPTHC) on fatigue properties were investigated. The results demonstrate that the fatigue properties of this bearing steel is obviously reduced after being pre-charged by HPTHC. The granular feature of "GBF" area for pre-charged specimens becomes light, sometimes even vanished. The distributions and size of the defects at the crack origins have no apparent effect on fatigue life.The fatigue life increases with increasing the relative size of "GBF" to inclusion. The stress intensity factor range at the periphery of crack origin before and after being pre-charged is approximately proportional to 1/3 power of the crack origin size, the crack growth threshold for "GBF" crack is proportional to 1/6 power of the "GBF" size. The additional stress intensity factor created by hydrogen multiplies up after being pre-charged by HPTHC, the calculated critical values of "GBF" are well in agreement with the experimental values.
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    Advances on the Study of Giant Dielectric Constant CaCu3Ti4O12/Polymer Composites
    SU Yan-li, HUANG He
    2014, 0 (2): 94-98.   DOI: 10.3969/j.issn.1001-4381.2014.02.018
    Abstract ( 803 ( PDF (528KB)( 422 Citation
    The preparation methods of giant dielectric constant CaCu3Ti4O12/polymer composites were reviewed. The factors affecting on the dielectric properties of the composites were analyzed. The development trend and the future prospect of CaCu3Ti4O12/polymer composites were previewed.
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