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  • 2002 Volume 0 Issue 9
    Published: 20 September 2002
      

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  • WANG Wei-guo, ZHOU Bang-xin, LIU Shu-guang, LI Wei-jun
    2002, 0(9): 3-6,25.
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    WANG Wei-guo, ZHOU Bang-xin, LIU Shu-guang, LI Wei-jun. Damping Capacity and the Grain Boundary Precipitates in Fe-Cr Based Damping Alloys[J]. Journal of Materials Engineering, 2002, 0(9): 3-6,25.

    The damping capacity and grain-boundary precipitates of some Fe-Cr based damping alloys annealed at 1473K was studied.The results indicate that the precipitates on the grain boundaries are chemically composed of chromium and iron and the damping capacity of the alloys is definitely related to the amount of the precipitates as well as to chromium content in the precipitates.Among the alloys investigated,the damping capacity of Fe-Cr-2Al-Si alloy is the highest while its amount of grain-boundary precipitates is the least with the lowest chromium content and vice versa to that of Fe-Cr-Al-Si(L)alloy.Though chromium content in the grain boundary precipitates of Fe-Cr-Al alloy is very close to that of Fe-Cr-Si alloy,the amount of grain boundary precipitates in the former is obviously lower than that in the latter and the damping capacity of the former is apparently higher than that of the latter.
  • GUO Ming-hu, YANG Yuan-sheng, HUA Fu-an, GUO Da-yong, HE You-liang, HU Zhuang-qi
    2002, 0(9): 7-9,43.
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    GUO Ming-hu, YANG Yuan-sheng, HUA Fu-an, GUO Da-yong, HE You-liang, HU Zhuang-qi. The Influence of Electromagnetic Field on the Solidification Structure of Centrifugal Casting Hastelloy C[J]. Journal of Materials Engineering, 2002, 0(9): 7-9,43.

    The solidification structures of Hastelloy C tubes produced by electromagnetic centrifugal casting(EMCC)process were studied.The results show that the EMCC promotes the formation of equiaxed grains.With the increase of electromagnetic field intensity,the percentage of equiaxed grains increases.The columnar-equiaxed transition is caused by the melt flow that scours dendrite arms and breaks them off under the effects of electromagnetic field.Furthermore,the electromagnetic field decreases the prime dendrite arm spacing(PDAS).The experimental results are consistent with Jackson-Hunt model.
  • WANG Xiang, LI Qing-fen, MA Xu-liang, Zeng Song-yan
    2002, 0(9): 10-13.
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    WANG Xiang, LI Qing-fen, MA Xu-liang, Zeng Song-yan. Wear Behavior of TiCp/ZA-12 Composites[J]. Journal of Materials Engineering, 2002, 0(9): 10-13.

    The TiCp/ZA-12 composites was fabricated by XDTM process combined with stirring casting and its wear properties under dry conditions were investigated using an MM-200 wear testing apparatus.The effects of TiCparticle content,applied load and sliding distance on the wear resistance properties of the composites were studied.The morphologies of the worn surfaces of composites and matrix alloy were investigated.The results indicate that the wear rate of the composites is lesser than that of the matrix alloy and it further decreases with the increase in TiC content.The wear weight loss of the composites and the unreinforced ZA-12 alloy increases with the increasing of applied load and sliding distance,but the increased extent of the former is smaller than that of the latter.Meanwhile there is a transition load in the course of wearing The wear is mild when the applied load is lower than the transition load,and changes to be severe when the applied load is higher than the transition load,and the transition loads for the composites are much higher than for the unreinforced alloy.
  • XU Qiang, ZHANG Xing-hong, QU Wei, HAN Jie-cai
    2002, 0(9): 14-17.
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    XU Qiang, ZHANG Xing-hong, QU Wei, HAN Jie-cai. Study of TiB2-Cu Composite by Combustion Synthesis[J]. Journal of Materials Engineering, 2002, 0(9): 14-17.

    The quasi-static consolidation in uniaxial compression of combustion synthesized TiB2-40%Cu(mass fraction)composite from Ti,B and Cu powders was investigated.Microstructure and properties of the composite was also studied by XRD,XEM,and EPMA.Thermodynamics of the system was calculated theoretically.The results show that the TiB2 is stable phase in the composite.Interphase TiCu can convert into stable phase.Only TiB2 and Cu phases,without other phases,exist in the synthesized product.It is consistent with the calculated result of thermodynamics.The microstructure is dense.Fine TiB2 reinforcement grows in near equivalent axis-like and block like shapes.Copper as binder phase exists between TiB2 and TiB2 particles.It is shown that copper improves the densification behavior during combustion synthesis.The relative density,bend strength and fracture toughness of TiB2-Cu composite is much higher than those of TiB2 ceramic.Crack-tip plastic blunting by a ductile metallic phase and crack deflection by the stress due to the difference of thermal expansion coefficient and elastic modulus between TiB2 and Cu are the principal mechanisms of toughness improvement of the composite.
  • ZHOU Yuan-xin, JIANG Da-zhi, XIA Yuan-ming
    2002, 0(9): 18-21.
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    ZHOU Yuan-xin, JIANG Da-zhi, XIA Yuan-ming. Testing and Characterization on In-situ Strength of Fiber in T300/Al Wires[J]. Journal of Materials Engineering, 2002, 0(9): 18-21.

    Based on extraction method,tensile experimental technique of fiber bundles and statistical theory of fiber strength,a new method has been developed to test and characterize the in-situ strength of fiber in unidirectional fiber reinforced metal matrix composite.Experimental results show that the modulus and strength of in-situ fiber bundles are quite lower than that of original fiber bundles.It is mainly because some damage occurs during manufactore process.According to the statistical constitutive theory of fiber strength,the statistical parameters of original fiber and in-situ fiber are obtained.
  • DU Shuang-ming, QIAO Sheng-ru, JI Gang-chang, HAN Dong
    2002, 0(9): 22-25.
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    DU Shuang-ming, QIAO Sheng-ru, JI Gang-chang, HAN Dong. Tension-Tension Fatigue Behavior of 3D-C/SiC Composite at Room Temperature and 1300℃[J]. Journal of Materials Engineering, 2002, 0(9): 22-25.

    Tension-tension cyclic-fatigue tests were conducted at room temperature and at 1300℃ in 10-4 Pa vacuum under the condition with a sinusoidal loading frequency of 60 Hz and stress ratio of 0.1 for a three-dimensional-woven C-fiber-SiC-matrix composite(3D-C/SiC)prepared by chemical vapor infiltration(CVI).The results show that the fatigue limit(based on 106 cycles)at room temperature is about 235MPa,which is 85% of its ultimate tensile strength,and the fatigue limit at 1300℃ is about 285MPa,which is 94% of its ultimate tensile strength.Based on the examination of the damage initiation,propagation and fracture morphology,the fatigue damage of this composite was also investigated.Fiber(fibers-bundles)-pullout length at 1300℃ is shorter than at R T.The fatigue damage initiated from the crossing sites of fibers-bundles,the damage of matrix surrounding fibers-bundles propagates with cyclic numbers.
  • QU Shao-bo, YANG Zu-pei, GAO Feng, XUE Jin, TIAN Chang-sheng
    2002, 0(9): 26-29.
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    QU Shao-bo, YANG Zu-pei, GAO Feng, XUE Jin, TIAN Chang-sheng. The Effect of K+ Doping on the Ordered Micro-region,Dielectric and Electrostrictive Properties of 0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3 Ceramics[J]. Journal of Materials Engineering, 2002, 0(9): 26-29.

    0.80Pb(Mg1/3Nb2/3)O3-0.20PbTiO3 relaxor ceramics with various content of K+ were fabricated by the columbite method and the effect of K+ doping on the phase structure,ordered micro region,dielectric and electrostrictive properties was investigated.The mechanism of K+ doping in dielectric and electrostrictive response was explored.Minor content of K+ doping hardly affectes the phase structure of PMN based ceramics,however,both of theoretical calculation and Raman scattering experiment demonstrateds that K+ doping decreases the size of ordered micro region slightly,K+ doping also slightly decreases dielectric and electrostrictive properties.
  • TANG Geng-ping, ZHANG Chang-rui, FENG Jian, ZHOU Xin-gui
    2002, 0(9): 30-32.
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    TANG Geng-ping, ZHANG Chang-rui, FENG Jian, ZHOU Xin-gui. Microstructure and Mechanical Properties of Si3N4/Nano-sized Si-C-N Powders at Room and Elevated Temperature[J]. Journal of Materials Engineering, 2002, 0(9): 30-32.

    Nano sized Si-C-N powders mixed with Si3N4,Y2O3,La2O3 was hot press sintered to form the SiC/Si3N4 composites.The microstructure of the composite was observed by means of SEM and HRTEM.The results show that the toughness and three point bending strength of the composite at room temperature is higher than those of monolithic Si3N4.The fracture toughness at room temperature and 1350℃ is 11.78 MPa·m 1/2 and 14.69 MPa·m1/2 respectively.The bending strength at room temperature and 1350℃ is 934MPa and 696MPa respectively the pinning effect of the SiC micro-crystal in Si3N4 grain and in grain boundary glass phase prevents the strength loss and increases the toughness of the composites at elevated temperature.
  • JIANG Bin, XU Bin-shi, DONG Shi-yun, DING Pei-dao
    2002, 0(9): 33-36.
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    JIANG Bin, XU Bin-shi, DONG Shi-yun, DING Pei-dao. Study on Microstructures and Sliding Wear Performance of n-Al2O3/Ni Composite Coating[J]. Journal of Materials Engineering, 2002, 0(9): 33-36.

    The nano-composite coating containing n-Al2O3 was prepared by electro-brush plating,and the sliding wear performance of the coatings was investigated.Its surface morphology is flat and compact.The nanoparticles in the coating are integrated tightly with the nickel and the distribution in the coating is uniform.Hardness of the coating can reach to HV700,higher 40% than the quick speed nickel coating.The results of sliding wear testing show that the wear resistance and friction coefficient of the nano-composite coatings increase with the increase of the n-Al2O3 particle content.When the n-Al2O3 is above 2 56%(mass fraction),the wear resistance decreases significantly.The wear mechanism of the nano-composite coating is mainly fatigue wear and that of the pure nickel coating is mainly adhesion wear.
  • ZHOU Qi, JI Geng-shun, ZHANG Jian-bin, WANG Ji-hong, WANG Jian-gang
    2002, 0(9): 37-39,46.
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    ZHOU Qi, JI Geng-shun, ZHANG Jian-bin, WANG Ji-hong, WANG Jian-gang. The Effect of Sulfides on Hydrogen-induced Cracking of Pipe-Line Steel[J]. Journal of Materials Engineering, 2002, 0(9): 37-39,46.

    The behaviour of hydrogen-induced cracking(HIC)of five kinds of steels was investigated in NACE solution.The experimental results show that the sensibility of HIC is increased with sulfides.The amount and distribution of sulfides should be controlled to improve the HIC resistance of steels.
  • LIU Wen-hu, JIANG Xiu-yu
    2002, 0(9): 40-43.
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    LIU Wen-hu, JIANG Xiu-yu. The Determination of Elements Nb,Ta,Zr,Mo,Al,Ti and La in Cobalt Based High-Temperature Alloy by Inductively Coupled Plasma-Atomic Emission Spectrometry[J]. Journal of Materials Engineering, 2002, 0(9): 40-43.

    Elements Nb,Ta,Zr,Mo,Al,Ti,La in cobalt based high temperature alloy were determined by inductively coupled plasma-atomic emission spectrometry(ICP-AES).Dissolution of sample,effect of examining solution medium,effect of basic and coexist enceelements,effect of internal element were experimentally studied,and factory verification was made.This method is fast,stable,and satisfactory for practical application.
  • WANG Jian-ping, WANG Qing-sui, CAO Wei-qing
    2002, 0(9): 44-46.
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    WANG Jian-ping, WANG Qing-sui, CAO Wei-qing. Application of the Method of Photogrammetric Orientated Determination[J]. Journal of Materials Engineering, 2002, 0(9): 44-46.

    Method of photogram metric orientated determination was presented,and applied to determine the crystallographic facet orientation on fracture of thermo-machanical fatigue of nickel base crystal superalloy DD3.The results show that the life of the alloy is high when the orientation of cryst allographic facet is<111>,the life is low when the orientation of the facet is<001>.
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