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  • Table of Content
      Jul. 2003, Volume 0 Issue 7 Previous Issue    Next Issue
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    Effect of Composite Materials on the C-ring Stress Corrosion Cracking of LY12CZ Aluminum Alloy
    LU Feng, ZHANG Xiao-yun, TANG Zhi-hui, ZHONG Qun-peng, CAO Chun-xiao
    2003, 0 (7): 3-6.  
    Abstract ( 238 HTML( PDF (1167KB)( 192 Citation
    C-ring stress corrosion method was conducted in 3.5% NaCl solution. Graphite epoxy composite materials (GECM) and LY12CZ aluminum alloy were coupled, in order to evaluate the effect of the galvanic corrosion between GECM/LY12CZ couple on the stress corrosion cracking (SCC of LY12CZ aluminum alloy. SEM technique was used to study the microstructure of the fracture cracking. The results show that galvanic corrosion promote the formation and propagation of the stress corrosion cracking of the LY12CZ aluminum alloy C-ring samples. Pit corrosion sites are decreased, corrosion rate of the grain boundary is accelerated, and sub-cracks are increased obviously by galvanic corrosion. The surface morphology of the GECM coupled with LY12CZ aluminum alloy do not change greatly.
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    Effect of the Content of Cr3C2 on the Mechanical Properties of Ti (C, N) Based Cermet
    HE Lin, HUANG Chuan-zhen, SUN Jing, LIU Han-lian, WANG Sui-lian, AI Xing
    2003, 0 (7): 7-9.  
    Abstract ( 244 HTML( PDF (673KB)( 190 Citation
    Ti(C0.5N0.5)-(Ni-Co)-Mo2C-Cr3C2 system cermet with low content of Mo2C was fabricated by hot pressure technology. The mechanical properties and SEM microphotography of the fracture surface and indention crack propagating on ground surface of the Ti(C,N) based cermet with different contents of Cr3C2 were discussed. It is shown that the flexure strength increases with the increase of Cr3C2 content and the fracture toughness of the cermet slightly decreases with the content of Cr3C2 when Cr3C2 content is less than 8%(mass fraction) and deeply decreases when Cr3C2 content more than 8%.
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    Microstructure and Properties of Vacuum Melting Cr3C2-NiCr Coating by Nickel-based Brazing Foil
    XU Xiang-yang, XU Bin-shi, LIU Wen-jin, LIU Shi-can, ZHONG Min-lin, ZHOU Zhong-rong
    2003, 0 (7): 10-13.  
    Abstract ( 290 HTML( PDF (1032KB)( 181 Citation
    A novel vacuum melting method, which was characterized by the application of brazing foil, was proposed. With BNi-2 nickel-based brazing foil, preplaced Cr3C2-NiCr adhesive coating was melted in the vacuum furnace. The microstructure and fretting wear resistance of the coating were studied. The results show that very dense coating is obtained. A good metallurgical bonding is achieved between not only coating and substrate but also hard phases and bonding phases. The microstructure of the coating is composed of hard phases such as chromium carbides, nickel borides, chromium borides and ductile phase that is nickel-based solid solution. Based on dense microstructure,excellent metallurgical bonding and hard phases strengthening, fretting wear resistance of vacuum melting Cr3C2-NiCr coating is remarkably superior to plasma spraying Cr3C2-NiCr coating and 1Crl8Ni9Ti stainless steel.
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    Crack Propagating and Machining Damage of Machinable Ce-ZrO2/CePO4 Ceramic
    LIU Zhi-feng, LIU Jia-chen, QIU Shi-peng, GE Zhi-ping, LI Hong-xiang, LI Yi-huan, LI Yan
    2003, 0 (7): 14-16.  
    Abstract ( 240 HTML( PDF (1269KB)( 197 Citation
    Crack propagating and machining damage of machinable Ce-ZrO2/CePO4 ceramic is investigated. It is found that the crack propagating in this ceramic, is different to that in others brittle ceramics. Weak interface forms in matrix with the adding of CePO4, where can yield micro-crack and produce crack deflection, branching and bridging, which lead to discontinuity of crack propagating in Ce-ZrO2/CePO4 ceramic. Furthermore,doping content of CePO4 has greatly effect on crack propagating and machining damage, it is not obvious of crack propagating discontinuity with small doping content of CePO4. At the same time, it has a great machining damage and is difficult to machine. On the contrary, samples has a diverge state of crack propagating with massive doping content of Ce-PO4, and has a little machining damage but mechanical properties deteriorate.
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    Study on the Corrosion-resistance of Zinc, Galfan and Galvalume Coating with Transient Linear Galvanostatic Polarization Method
    WEI Yun-he, ZHU Chen-fu, YU Ping, GUO Xiao-yu, REN Jun-he, ZHANG Chang-qiao, SUN Ying
    2003, 0 (7): 17-19.  
    Abstract ( 254 HTML( PDF (270KB)( 150 Citation
    The polarization resistances(Rp)of zinc, Galfan and Galvalume coating in NaCl, Na2SO4 and NaCl+Na2SO4 solution was determined with transient linear galvanostatic polarization method. At the beginning of the corrosion test, the Rpof Galvalume and Galfan was about three and two times to zinc coating. With the corrosion going on, the Rp of zinc and Galfan was continuously reducing, but the Galvalume’s Rp was rising except in NaCl solution. The results show that corrosion product of Galvalume can protect the coating, but the zinc and Galfan’s can not.
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    The Effect of Element C on Heat-treatment Processing Temperature Window of 600℃ High Temperature Titanium Alloy
    HAO Meng-yi, CAI Jian-ming, DU Juan, LI Zhen-xi
    2003, 0 (7): 20-22.  
    Abstract ( 246 HTML( PDF (839KB)( 262 Citation
    The effect of element C on heat-treatment processing window of 600℃ high temperature titanium alloy (Ti60) was studied in this paper. The results indicate that minor element C can affect α+β→β polymorphic transformation process of Ti60 effectively. Tiny element C can increase the β transus temperature (Tβ),and then slow the transformation rate of α volume fraction from (1.5%-2%) ·℃-1 to about 0.5% ·℃-1.This feature of C can lead to a relatively stable primal α volume fraction within a wider temperature window, consequently, which make the alloy's creep properties stable.
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    Study on Circuit Analog of Radar-absorbing Structure Composites
    JIANG Shi-cai, XING Li-ying, ZHANG Bao-yan
    2003, 0 (7): 23-25.  
    Abstract ( 184 HTML( PDF (281KB)( 210 Citation
    The size of the circuit analog, the location of the circuit analog, the absorbent, content of composite had been investigated. It has been found that the circuit analog play the role of reflection screen and can be used to adjust the radar-absorbing structure composite surface-resistance, improve the EM wave energy attenuation property of the radar-absorbing structure composite and widen the work frequency band width of EM wave . Therfore, through rational composite material design and preparation , the radar-absorbing structure composite with circuit analog can have good radar-absorbing property.
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    Effect of Heat Treatment on Eutectic Silicon Morphology and Mechanical Property in AlSiCuMg Cast Alloys
    LI Run-xia, LI Rong-de, LI Chen-xi, YANG Xiu-ying, HU Zhuang-qi
    2003, 0 (7): 26-30.  
    Abstract ( 245 HTML( PDF (1532KB)( 221 Citation
    After observation of eutectic silicon morphology of AlSiCuMg cast alloy and measurement of various parameters of silicon particles, it is found that, during solution heat treatment, the change of eutectic silicon particles morphology and mechanical property can be classified into three stages; In initial stage, breaking and passivation of silicon particles result in the improvement of plasticity of alloy. In intermediate stage, because of spheroidizing of silicon particles and comprehensive dissolving of elements, the mechanical properties of alloy reach peak value. In the final stage, the coarsening process of silicon particles obeys the LSW theory and the morphology of silicon particles is worsening. By TEM observation of samples aged at 175℃ for different time it is found some excess silicon particles precipitate during aging heat treatment and grow fast with prolongation of aging time.
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    Study on Microstructure and Co-deposition Mechanism of n-Al2O3/Ni Composite Coating Prepared by Electro-brush Plating
    TU Wei-yi, XU Bin-shi, JIANG Bin, DONG Shi-yun
    2003, 0 (7): 31-35.  
    Abstract ( 244 HTML( PDF (1064KB)( 195 Citation
    The surface charge and particle diameter distribution of n-Al2O3 powder were investigated by measuring its Zeta potential and particle size in quickly nickel brush plating solution. The surface morphology and microstructure of composite coating by electro-brush plating were observed by SEM and TEM. The distribution of n-Al2O3 in the coating had been gotten. The result shows that the nano-particle surface charge is negative and its diameter distribution is more wide in brush plating solution. The diameter of n-Al2O3 particle is in the range of tens of nanometer in coating. Brush movement and solution convection influenced the size of the nano-particle that have entered coating at some degree. According to these results, this paper discusses that co-deposition mechanics of n-Al2O3/Ni should be mechanics mechanism.
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    Study on Damping Properties of PU/VER IPN Materials
    QIN Chuan-li, CAT Jun, TANG Dong-yan, ZHANG Ju-sheng, CAI Wei-min
    2003, 0 (7): 36-39.  
    Abstract ( 280 HTML( PDF (734KB)( 233 Citation
    The influence of thermodynamic, dynamic factors and component ratios on damping properties of PU/VER IPN materials was studied by dynamic mechanical analysis (DMA).It is found that the damping properties of general PU/VER (St) IPN materials (polystyrene is VER’s comonomer) are improved by introducing acrylic esters as VER’s comonomers and the IPN material with long ester groups has excellent damping properties; the IPN materials with the broad transition range can be prepared by adjusting the relative polymerization rate and component ratios. When the component ratios are 80/20, 70/30 and 60/40, tanδ values are higher than 0.3 for a temperature range of at least near 80℃. The relation between microstructure and damping properties of IPN materials was further studied by TEM.
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    Study on the Application of Liquid Forging Technology in Casting Aluminum Alloy
    WEI Li-jun, MA Feng-lei, LI Ren-jiang
    2003, 0 (7): 40-42.  
    Abstract ( 217 HTML( PDF (327KB)( 394 Citation
    Casting aluminum alloy is a kind of metal material, which is used extensively but difficult to form. Liquid forging technology can effectively increase materials flexible and mechanial properties and lower the manufacturing costs of casting alloy parts, especially complex-shaped parts. Formed in liquid forging method, casting aluminum alloy parts can get almost every mechanial properties of parts formed in traditional method. Parts of casting aluminum ZL103 formed in liquid forging can reach 320MPa bending strength, 100HB hardness and 7.0% elongation.
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    Review on Preparation and Properties of the Relaxor Ferroelectric Single Crystals and Textured Ceramics
    ZHAO Li-li, TANG Bin, ZHAO Ming, FAN Hui-qing, TIAN Chang-sheng
    2003, 0 (7): 43-48.  
    Abstract ( 237 HTML( PDF (724KB)( 297 Citation
    Preparation and electrical properties of the relaxor ferroelectric crystals and textured Pb (Mg1/3Nb2/3)O3-PbTiO3 (PMNT) ceramics are reviewed. Most of the single crystals are prepared by high-temperature solution growth, Bridgman method or solid recrystallization method. The properties depend on the single crystals’ directions very strongly, and (001) sliced crystals have the best piezoelectric properties. Now the single crystals with size of more than 40mm have been reported. But misdistribution of components is main factor to affect the piezoelectric properties of materials. However, [001]-textured PMNT ceramics have showed excellent piezoelectric properties, which can be prepared by TGG (or RTGG) method. The preparation of this kind of the ceramics requires low cost and less time, whose piezoelectric constant d33 can obtain 60%-80% that of the single crystal. Moreover, the dielectric permittivity of textured PMNT ceramics is relatively higher than that of the single crystals prepared by solid recrystallization method. Therefore, the preparation of grain oriented textured ceramics shows high promising trend in application.
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