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      20 June 2012, Volume 0 Issue 6 Previous Issue    Next Issue
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    Effects of Cyclic Hygrothermal on Properties of Nomex Honeycomb/Epoxy Sandwich
    ZHAO Yan, DONG Hao, HU Jian-ping, LI Xiang, LIU Jian-hua
    2012, 0 (6): 1-6.  
    Abstract ( 984 ( PDF (1708KB)( 330 Citation
    The absorbing and the desorption curves of Nomex/epoxy honeycomb-sandwich 1(sample 1) and Nomex/epoxy honeycomb-sandwich 2 (sample 2) were obtained after 7 days hygrothermal circulation and 14 days hygrothermal circulation. The results show that the saturated moisture absorption rate and water retention of sample 1 are higher than that of sample 2 and the moist heat resistance property of sample 1 is superior to that of sample 2. The mechanical properties and dielectric properties of dry specimens and specimens after hygrothermal circulation were tested.It is indicated from the results that the shear performances of the specimens are highly affected by the hygrothermal circulation, especially for sample 2.The sample 1 has more stable mechanical properties after hygrothermal circulation than sample 2.The dielectric properties of the two specimens are also discussed.
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    Study on Measuring Optical Distortion of Aircraft Acrylic Sheets by Point Source Vanishing
    ZHU Zi-hua, ZHANG Ran, WANG Da-yong, ZHANG Hao-yu
    2012, 0 (6): 7-10.  
    Abstract ( 766 ( PDF (1291KB)( 282 Citation
    When the optical distortion vanishing angles of aircraft acrylic sheets were measured by the point source vanishing method according to the present stipulation operating procedures, the optical distortions in the further distance from the central axis line of aircraft acrylic sheet were measured in the positions that were both close to and away from the stripe curtain. As a result, the acquired measure data are quite different and it has seriously effect on the inspectors to judge whether the measure sheet is qualified or not. In fact, the phenomenon is in connection with such factors as the defect distance from the central axis of the sheet and the defect cross section shape. A solution method is found out that a horizontal sliding device is installed on the existing rotation measure rack. Thus, the measure sheet can be horizontally slid close to the rotation axis of the rack and rotated, then the vanishing angles in the different positions are got respectively and the maximum angle value is taken as the measurement result.
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    Investigation on Deformation Behavior of a New Type Al-Zn-Mg-Cu-Zr Alloy
    WANG Sheng-qiang, WANG Shao-hua, MA Zhi-feng, WANG Qiang, WANG Jian-guo, LU Zheng
    2012, 0 (6): 11-15.  
    Abstract ( 564 ( PDF (2885KB)( 471 Citation
    Deformation behavior of a new Al-Zn-Mg-Cu-Zr alloy is investigated by dynamic upsetting compress test. The results show that, when the deformation temperature of Al-Zn-Mg-Cu-Zr alloy is below 350℃, there is dynamic precipitation behavior during deformation because of low temperature. Further deformation of the alloy will be difficult due to small precipitates in the alloy. When the deformation temperature is above 400℃, there is no dynamic precipitation behavior in the alloy. When the deformation temperature is higher than 450℃, there is dynamic recrystallization and size increase of grain. The results of dynamic upsetting test show that the appropriate forging temperature of Al-Zn-Mg-Cu-Zr alloy is range of 400-420℃, and the maximum deformation is 60%.
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    Research on Remanufacturing Process of a Typical Aluminum Alloy Engine Cylinder Head
    CHEN Yong-xiong, WEI Shi-cheng, LIANG Xiu-bing, DONG Shi-yun, XU Bin-shi
    2012, 0 (6): 16-20.  
    Abstract ( 860 ( PDF (2197KB)( 313 Citation
    Considering the requirement of remanufacturing a type of disused automobile engine aluminum cylinder head, the invalidation characteristics of the engine cylinder was analyzed, and the remanufacturing process of high velocity arc spraying Al-RE coating was put forward and investigated. The experiment results show that, ring type impress and out-of-tolerance flatness on the cylinder head surface are the main invalidation behaviors. Near the impress zone, some white strip-like Si phase was found, and the hardness increased. The high velocity arc sprayed Al-RE coating has a dense structure and the hardness is slightly lower than that of the LM25 TF aluminum alloy substrate. After the heat impressing experiment, the coating is adhered well with the substrate, no cracks or breakaway are found. Combining the experimental and case-study results, it can be concluded that the high velocity arc spraying Al-RE coating technology is available for remanufacturing aluminum alloy cylinder heads.
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    Preparation of Ba2TiSi2O8 Glass-ceramics
    YANG Lan-he, LIU Gui-shan, MA Tie-cheng, HU Zhi-qiang, WU Kai-zhuo, LIU Jing-xiao
    2012, 0 (6): 21-23.  
    Abstract ( 771 ( PDF (1110KB)( 313 Citation
    Ba2TiSi2O8(BTS) glass-ceramics have the excellent properties such as piezoelectricity,pyroelectricity, and nonlinear optical properties. BTS glass-ceramics were prepared by sol-gel method. The chemical reactions and energy changes of BTS dry-gel were analyzed by Differential Thermal Analyzer (DTA). The phase composition of BTS powders were tested by X-ray diffraction (XRD). The particle size of BTS powders was measured by laser particle size analyzer. The microstructure of BTS glass-ceramics samples was characterized by Scanning Electron Microscope (SEM). The results showed that the suitable temperature of BTS powders synthesis was 850℃, and the average size of BTS powders was 1.73μm. The BTS glass-ceramics sintered at 1250℃ have the properties of densification, low porosity and uniformity.
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    Research on the Joint of Friction Stir Lap Welding for Aluminum Alloy 5083
    CHEN Ying, FU Ning-ning, SHEN Chang-bin, GE Ji-ping
    2012, 0 (6): 24-27.  
    Abstract ( 962 ( PDF (2282KB)( 366 Citation
    Aluminum alloy 5083 was welded by friction stir lap welding in the test. The tensile-shear test of the lap joints was tested by universal testing machine and the fracture behavior of the joint was examined by scanning electron microscopy, microstructures of the joint were investigated by optical microscope. The results showed that microstructure of the upper and lower in the zone of the tool were refined, although the length of the pin was shorter than the upper sheet. And micro-hardness showed that the hardness of the zone of the pin approached to the hardness of base metal. In the tensile-shear test, the interface didn’t fracture, but fracture location exists in the HAZ of the upper sheet. The joint strength constant can reach about 80% of the base metal. Fractographs confirm that the fracture of the joint is the mode of ductile fracture.
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    Stamping Properties of Cold-rolled Fe-6.5%Si Alloy Sheet
    YAN Li-li, FANG Xian-shi, LIANG Yong-feng, YE Feng, LIN Jun-pin
    2012, 0 (6): 28-31.  
    Abstract ( 864 ( PDF (3504KB)( 300 Citation
    Fe-6.5%Si alloy has excellent soft magnetic properties, such as high resistivity, high permeability, low core loss, etc. However its room temperature brittleness impedes its industrial applications. In this paper, it is reported that cold-rolled sheet of 0.3mm thick was fabricated using the traditional rolling equipment by a gradually ductillization process. Tensile and stamping properties of this cold-rolled sheet were investigated from room temperature to 250℃. It is found that the cold-rolled sheet exhibits certain tensile plasticity at 100℃ and upwards, with dimple fractures. Reasonable stamping parameters are concluded: 0.04mm for the mould clearance and 150℃ for the stamping temperature.
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    Using Silica Nanoparticles Reinforce Interfacial Property of Carbon Fiber/Epoxy Composites
    LI Ling-yun, LIU Lu-qi, TANG Long-cheng, GAO Yun, ZHANG Zhong
    2012, 0 (6): 32-36.  
    Abstract ( 764 ( PDF (2161KB)( 301 Citation
    Interfacial property is a key factor that determines the mechanical performance of fiber reinforced polymer composites. The interfacial property of carbon fiber/epoxy composites was enhanced by addition of silica nanoparticles. The single fiber fragmentation test was employed to investigate the reinforcing mechanism. The results showed that the silica nanoparticles sized on the fiber surface and dispersed in epoxy matrix could significantly improve interfacial property. When the content of silica on the surface and in the matrix were 4.9g/m2 and 25%(mass fraction), the interfacial shear strength (IFSS) improved 10.0% and 15.0% respectively. By analyzing the phenomenon of birefringence and SEM of fracture faces, the perfect dispersion of silica and the mechanical interlocking between nanoparticles and grooves on fiber surface are believed to be the factors sustaining better fiber/matrix interfacial property.
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    Effect of Heat Treatment Technology on Microstructure, Mechanical Property and Corrosion Resistance of Nickel-base Alloy Inconel718
    SONG Yi-si, GAO Wan-fu, WANG Chao, LEI Xiao-wei, WANG Hua-liang
    2012, 0 (6): 37-42.  
    Abstract ( 1301 ( PDF (4485KB)( 668 Citation
    Research on the microstructure, mechanical property and corrosion resistance of nickel-base alloy, Inconel718 after application of different heat treatment techniques was carried out. The result indicates that, as temperature increasing, the grain grows up and the phase δ dissolves into the matrix. After aging, the phase γ" precipitates from the alloy. The hardness of the alloy, as a result, becomes higher than that of the alloy after being subjected to the solid solution treatment. After the solid solution treatment at 1000℃ and aging, the hardness and yield strength reach the maximum. Corrosion test indicates that the nickel-base alloy, Inconel718 possesses excellent corrosion resistance regardless of heat treatment. The stress corrosion test under the atmosphere of H2S/CO2 at high temperature and pressure shows that there is no crack in the alloy Inconel718.
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    Surface Artifactitious Smoothness Analysis of Honeycomb Sandwich Panel
    XIA Sheng-lai, HE Jing-wu, WANG Yao-dong
    2012, 0 (6): 43-47.  
    Abstract ( 715 ( PDF (1842KB)( 501 Citation
    Honeycomb sandwich structure with high specific strength, stiffness and light weight, etc., are widely used in aerospace applications. Therefore, analysis of its mechanical properties has a great value in theoretical research and engineering application. Using the honeycomb sandwich panels that are commonly used for the satellite structure, sandwich panel test measured the surface roughness. According to theory, this paper deduced the equivalent material parameters of honeycomb sandwich structure, and also analyzed the panel surface roughness with finite element software MSC.Patran/Nastran. Comparison between the test results and calculate results with the difference of 5.9%, indicate the feasibility of theoretical derivation. According to the equivalent sandwich theory, proposed the establishment of the equivalent coefficient database about the cellular equivalent parameters which was the common specifications, facilitating the engineering applications of honeycomb sandwich structure.
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    Corrosion Resistance and Self Healing Ability of Silicate Conversion Coatings on Hot Dip Galvanized Steels
    YUAN Mei-rong, LU Jin-tang, KONG Gang, CHE Chun-shan
    2012, 0 (6): 48-53.  
    Abstract ( 614 ( PDF (2797KB)( 317 Citation
    The silicate conversion coating was prepared by immersing hot dip galvanized (HDG) steel in sodium silicate solution with a SiO2∶Na2O molar ratio of 1.00 or 3.50, respectively. The corrosion resistance of coatings was investigated by neutral salt spray (NSS) test, Tafel polarization and electrochemical impedance spectroscopy (EIS) measurement. NSS corrosion process of the coatings scratched by the edge of knife was analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The results show that the superior corrosion resistance and self healing ability are obtained from the silicate coating pretreated in sodium silicate solution with higher SiO2∶Na2O molar ratio. During the corrosion process, silicate anions migrate from the coating to the scratch, on which a new passive coating composed of Zn, O and Si is formed and the corrosion is suppressed. Moreover, it is observed that by the atomic force microscopy (AFM), the silicate coatings obtained in the sodium silicate solution with molar ratio of 3.50 is more compact, which is favor of the migration of silicate anions. The detail of corrosion process of the scratches on silicate coatings is discussed.
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    Corrosion Behaviour of Low Hydrogen Brittleness Brush Plating Cadmium on A100 Steel in Marine Environment
    LIU Peng, WANG Xu-dong, CAI Jian-ping, TANG Zhi-hui
    2012, 0 (6): 54-58.  
    Abstract ( 930 ( PDF (2838KB)( 348 Citation
    The corrosion behaviour of low hydrogen brittleness brush plating cadmium on A100 steel was investigated under the outdoor exposure environments in Hainan. The corrosion dynamics curve reflects the change of the coating corrosion weightlessness. The features for the various corrosion stages were characterized by the electrochemical impedance spectroscopy, and the effect of corrosion on the mechanical properties was also discussed. The results indicate that the brush plating cadmium has a good corrosion resistance, corrosion rate increase with exposure time. The mechanical properties are obviously effected by corrosion and the corrosion leads to tensile strength decrease. The microstructure of test specimens presents a brittle fracture characteristic.
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    Study on the Microstructure and Property of Contact Fatigue Damage of Plasma-sprayed Fe-based Alloy Coating
    ZHANG Zhi-qiang, LI Guo-lu, WANG Hai-dou, XU Bin-shi, PIAO Zhong-yu
    2012, 0 (6): 59-62.  
    Abstract ( 760 ( PDF (1811KB)( 310 Citation
    Fe-based alloy coating was prepared on 1045 steel by the supersonic plasma spraying device. The microstructure of the coating was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Microhardness of coating cross-section was measured using microhardness tester. Process of contact fatigue damage was monitored using acoustic emission technology on a ball-on-disk tester. The results show that the microstructure of the coating consists of α(Fe,Cr) phase and reticular Cr7C3. Nanocrystalline α(Fe, Cr) phases were homogeneously distributed around the cracks. Damage degree of contact fatigue could be reflected by RMS of acoustic emission parameter. Delamination is the final failure mode of the coating when the contact stress is 1.8489GPa and rotational speed is 2000r/min.
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    Study of the Restoration Behavior of Breakage of Different Coatings on the Surface of Steel by a Hydrophobic Agent
    CHEN Yuan, LI Wei-ping, LIU Hui-cong, ZHU Li-qun
    2012, 0 (6): 63-66.  
    Abstract ( 565 ( PDF (1407KB)( 309 Citation
    Surface coatings of aircraft components can possibly be broken and scratched during assembly and transportation, and gap junctions of some fitting parts are channels of corrosion medium’s erosion and sensitive areas of corrosion. The restoration behaviors of the hydrophobic agent (BH-102) used in aircraft components for the breakages of three basic coatings (the epoxy silicone coating, the polyurethane coating and the AV15 coating) are investigated. Furthermore, the corrosion properties of coatings after restoration are also researched under the neutral salt spray environment and the hydrothermal environment. Results are presented that hydrophobic layer which can effectively prevent corrosion at coating breakage areas formed on the restoration areas of basic coatings. The restoration effect (anti-corrosion property) on the AV15 coating breakage is better than the other two coating-breakages by the hydrophobic agent, and that is because the hydrophobic agent can cause synergistic effect with the film formers and the inhibitor components of AV15 coating.
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    New Simplification Method of Thermosetting Resin Curing Kinetic Models
    WANG Xiao-xia, WANG Cheng-guo, JIA Yu-xi, LUO Ling
    2012, 0 (6): 67-70.  
    Abstract ( 809 ( PDF (1444KB)( 306 Citation
    Temperature-time-transition (TTT) diagram is a useful tool for analyzing and designing the curing process, which has an important research value. The traditional iso-conversional curves drawing process in TTT diagram is a complicated process which is time consuming and costly. The relationship of temperature, time and degree of cure is controlled by the curing kinetic equation. From the perspective of the curing kinetic equation, studying the iso-conversional curves with the numerical simulation method is a novel method which can reduce both time and cost. For two kinds of resin curing kinetics models, the resin degree of cure is simulated, and the simulation program has been verified. Based on this work, the iso-conversional curves of two kinetic models are plotted and the relationship of the temperature, time and degree of cure is discussed. The result shows that a negative linear relationship exists between the temperature and the logarithm of the time. Then by curve fitting method a relatively simple relationship of the iso-conversional curves is obtained which can be used more conveniently in engineering practice without cumbersome computation.
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    Three Dimensional Numerical Analysis on Dynamic Mechanical Property of Tungsten Alloys
    LIU Hai-yan, SONG Wei-dong, LI Jian-qiao
    2012, 0 (6): 71-75.  
    Abstract ( 744 ( PDF (1660KB)( 285 Citation
    Dynamic behavior of tungsten alloys under impact loadings was investigated by using numerical simulations. Three dimensional finite element unit cell models with typical micro-structure of tungsten alloys were established. The dynamic mechanical properties of tungsten alloys under tensile loadings were investigated by numerical simulations. The effect of strain rates on the mechanical properties was analyzed. The stress and strain contours of the unit cell model at different strain rates were given. The reliability of the finite element models was verified through the comparison with experimental results.
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    Effect of Ru on the Tensile Property in Single Crystal Superalloys
    LIU Li-rong, ZU Guo-qing, LI Xiao-yu, JIN Tao, HU Zhuang-qi
    2012, 0 (6): 76-79.  
    Abstract ( 726 ( PDF (2482KB)( 405 Citation
    In order to investigate the effect of Ru in single crystal superalloys containing rhenium, the tensile property and deformation microstructure were studied by scanning electron microscope and transmission electron microscope. The results show that with the increasing of ruthenium content, the size of γ′phase decrease and the cubic degree increase. At 900℃,the yield strength and tensile strength increase slightly,with the increase of Ru additon. The fracture mode is all pure shear mode for these three alloys. The deformation mechanism is the dislocation pair by anti-phase domain. The additions of ruthenium increase the tensile strength slightly,but not change the deformation mechanism and fracture characteristics.
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    Finite Element Computation of X-cor Sandwich’s Tensile Modulus
    DANG Xu-dan, WEI Meng, XIAO Jun
    2012, 0 (6): 80-85.  
    Abstract ( 679 ( PDF (3363KB)( 264 Citation
    After analyzing photomicrographs of Z-pin ends’ micro-structures in X-cor sandwich, the basic hypothesis that the resin regions around Z-pin ends are elliptic is proposed. The finite element model of X-cor sandwich’s tensile modulus was established and the finite element software ANSYS was used in the computation of tensile modulus. The effects of Z-pin angle, diameter and density on the X-cor sandwich’s tensile modulus were analyzed. The numerical analysis results indicate that as the Z-pin angle increases the X-cor sandwich’s tensile modulus decreases, as the Z-pin diameter increases the X-cor sandwich’s tensile modulus increases and as the Z-pin density increases the X-cor sandwich’s tensile modulus also increases. Through the analysis of finite element model, the effect trends of X-cor sandwich’ parameters to the tensile modulus are achieved and the error range is ?10%. So the rationality of proposed finite element model is verified and the finite element model can be used to evaluate the X-cor sandwich’s tensile modulus.
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    Effect of Mixture of Plasticizer on Properties of PVA Films
    REN De-cai, LIN Peng, QIAN Lei, HE Pei-feng, DU Yu-hong, XUE Rui
    2012, 0 (6): 86-90.  
    Abstract ( 948 ( PDF (1774KB)( 319 Citation
    Modified Polyvinyl alcohol (PVA) films were prepared by casting from the solutions using urea/triethanolamine as a mixed plasticizer. The interactions between urea/triethanolamine and PVA were studied by FT-IR. Crystallinity and thermoplasticity of modified PVA were tested by TGA, DSC, and XRD. At the same time, mechanical properties, light transmission rate, water solubility of modified PVA also were tested. The results showed that mixture of plasticizer can decrease the extent of inter-or intramolecular hydrogen bonds in PVA, crystallinity and melting point of modified PVA depresses without bringing about any obvious impact on the thermal decomposition temperature. With the mass fraction of mixture of plasticizer increasing, the modified PVA had lower strength and higher elongation at break, good light transmission rate, lower degree of swelling and higher solubility.
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    Development of Hot Tearing on Cast Superalloys Used for Auto Turbocharger Turbine Wheel
    SHI Zhao-xia, DONG Jian-xin, ZHANG Mai-cang
    2012, 0 (6): 91-96.  
    Abstract ( 885 ( PDF (1164KB)( 453 Citation
    Hot tearing tended to occur in the turbine wheel blade when superalloys were used for auto turbocharger turbine wheel, which affected the application of cast superalloys used in turbocharger turbine wheel. Several cast superalloys which were currently widely used in auto turbocharger turbine wheel were introduced. The hot tearing mechanisms for castings were reviewed. Effects of the elements,such as Al,Ti,C,Zr and Hf on hot tearing susceptibility of cast superalloys were emphatically analyzed. Effects of solidification mode of superalloys and casting process parameters,such as characteristics of moulds,pouring conditions,constructions of castings and pouring system on hot tearing were also reviewed. In addition,measures to prevent hot tearing were proposed.
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