WANG Jing, WANG Yi-san, DING Yi-chao, SHI Jian-guo. (Ti,V)C Particles Reinforced Iron-based Composite Produced In-situ[J]. Journal of Materials Engineering, 2006, 0(9): 3-5,26.
The(Ti,V)C particles reinforced iron-based composite was produced in-situ. The microstructure and wear-resistance of the Fe-(Ti,V)C composite were studied by SEM,electron probe and XRD.The results show that spherical(Ti,V)C particles exhibit finer size and homogeneous distribution in the matrix,and under condition of dry sliding with heavy loads,Fe-(Ti,V)C composite shows great wear-resistance.
LAI Yu-mei, CHENG Ru, WANG Xiao-dong, HUANG Pei. Thermal Transition Behavior for Thermoplastic Polyimide[J]. Journal of Materials Engineering, 2006, 0(9): 6-9,13.
Molecular weight and molecular weight distributions of thermoplastic polyimide(TPI) were measured by GPC(Gel Permeation Chromatography).And the glass transition temperature(Tg) of TPI was analyzed by DSC.The effect of factors,such as molecular weight,heat treated temperature and heat treated time,on Tg was also considered.The results showed that Tg was increased with the molecular weight,and the Kanig-Ueberreiter equation provided a good fit to Tg and number-average molecular weight.Due to the PI structure feature-having the free end group,solid therm-cyclization could be carried out at high temperature.Accordingly,the molecular weight was increased with the heat treated temperature and time,and then,Tg was increased.
YAO Yi-jun, QIU Tai. Study on Rheological Behavior of Slurry for Aluminum Nitride Ceramics[J]. Journal of Materials Engineering, 2006, 0(9): 10-13.
Effects on the rheological behavior of slurry for tape-casting aluminum nitride substrate were studied systematically.The effects of milling time,solvent,dispersant,binder and plasticizer on the rheological behavior of slurry were studied.All the rheological curves obtained under experiment conditions can be correlated with Hershel Bulkley model.Correlated Hershel Bulkley yield stress τc can reflect the stability of suspension.The results show that τc of AlN slurry is low when the volume fraction of dispersant is 2.5%;τc increases with the increase of solid loading;τc is the lowest when the milling time is 4h in the experiments.The viscosity of slurries decreased sharply with the increase of the R ratio(plasticizer/binder),the rheological behavior of aluminum nitride slurries were improved obviously.
LIU Li-rong, JIN Tao, SUN Xiao-feng, GUAN Heng-rong, HU Zhuang-qi. Effects of Titanium Content on Microstructural Evolution During Prolonged Aging in a Nickel-base Single Crystal Superalloy[J]. Journal of Materials Engineering, 2006, 0(9): 14-16,19.
The microstructural evolution of a nickel-base single crystal superalloy with different content of titanium as-cast state and during prolonged aging at 1000℃ was investigated.The results showed that with the increase of titanium,the size and percentage of γ/γ' eutectic in interdendritic region increased obviously,at the same time,the area of interdendritic region was enlarged.During prolonged aging at 1000℃,the rafting level increased gradually with the increase of titanium.After 500h,TCP phase was not found in the three alloys;after 1000h with the increase of titanium,TCP phase precipitated gradually.
DING Sheng, LI Ning, XU Yong-gang, QIU Shao-yu, ZOU Hong, LI Cong. Effects of Rare-earth on Damping Capacity of Fe-17.5Mn Alloy[J]. Journal of Materials Engineering, 2006, 0(9): 17-19.
The damping capacity of the Fe-17.5Mn and Fe-17.5Mn-0.3Mm(rare-earths) alloys was measured by reversal torsion device.The microstructure was observed with the Olympus optical microscope.The results show that the damping capacity of Fe-17.5Mn-0.3Mm is obviously higher than that of Fe-17.5Mn binary alloy after quenched at 1000℃ for 1h.Addition of 0.3% mass fraction rare-earth elements results in more and thinner martensites in the Fe-17.5Mn-0.3Mm alloy.The more areas of the γ/ε interface and ε-martensite variant boundary in unit volume bring more microstructural damping resources on vibration,thus improving the damping capacity of Fe-17.5Mn-0.3Mm.
GAO Juan-juan, ZHANG Zuo-guang, LIANG Zi-qing, TANG Bang-ming, YI Xiao-su. Research on Vertical Permeability of Fabric Preforms[J]. Journal of Materials Engineering, 2006, 0(9): 20-22,63.
Based on the Darcy's law,the effects of fabric layers,the mass fraction of tackifier and the angle between different fabric layers on vertical permeability of different fabric preform types were studied.Experiments indicate that the flow behavior of test fluid which is still steady flow in the vertical direction is controlled by the Darcy's law,while fabrics are of the certain tackifier mass fraction.As the number of the fabric layers increases,the flow velocity decreases,and the vertical permeability increases gradually.The vertical permeability of the fabrics first increases and then decreases,as the mass fraction of the tackifier increases.The angle between different fabric layers also has remarkable effect on the vertical permeability.
XU Jin-yong, GAO Qing, LONG Xiang-qian, XU Min, GAO Yuan, XU Zhong. Effect of Cryogenic Treating on Wear Resistance of Plasma Alloying Surface Layer of Q235 Steel[J]. Journal of Materials Engineering, 2006, 0(9): 23-26.
Plasma alloying and heat treatment technology were introduced to modify the content of the surface layer of Q235 steel sample.Using the technology,alloying elements Mo,Cr,C can be obtained in the surface layer of Q235 steel sample.The content is about up to that of high speed steels.The fundamental principle is that alloying elements Mo,Cr are penetrated into the Q235 steel samples by glow discharge sputtering so that the Mo,Cr in alloyed layer is about 12%(mass fraction) and 4% respectively in the Q235 steel surface layer and so alloyed layer is similar to molybdenum high speed steel with surface carburized up to 2.0%.Large eutectic ledeburite is not found.After hardening + low tempering and hardening+cryogenic treatment 2h+low tempering,it is found that the hardness of cryogenic treatment surface is up to 1600HV which much higher than that of other technology.The abrasion test results indicate that the number of friction coefficient of the latter is lower than that of the former and wearability of the latter increases by a factor of 1.6 comparing to that of the former.
SUN Xu-wei, ZENG Su-min, CHEN Zhi-qian, CHENG Nan-pu, GAN Bing-tai. Effect of Fabricating Parameters on Spatial Distribution of Reinforcements in Aluminum Matrix Composites[J]. Journal of Materials Engineering, 2006, 0(9): 27-30,52.
SiCp/6066Al composites were fabricated by the method of high energy ball milling and quick hot extrusion at low temperature.The effect of this method on the SiC particles distribution was investigated.The results indicate that high energy ball milling is the most effective powder mixing method,which can remarkably improve the shape of reinforcements,reduce their size and lead to the dispersed homogeneous distribution of reinforcements in quantity at smaller micro-areas in the matrix.By using the low ductility and great distortion of matrix,quick hot extrusion at low temperature can ulteriorly reduce the size of reinforcements and produce fine axial symmetrical reinforcements which can more easily distribute homogeneously with the matrix's flow.It can also improve or eliminate the gather of reinforcements at micro-areas in the matrix or mostly depress the gather degree of reinforcements.High energy ball milling combined with quick hot extrusion at low temperature is the most effective method which leads to the uniform distribution of reinforcements in the matrix at micro-level.
ZHANG Xiao-hua, LIU Dao-xin. Effects of Electrospark Surface Strengthening and Shot Peening on Fretting Fatigue of Ti811 Alloy at Elevated Temperature[J]. Journal of Materials Engineering, 2006, 0(9): 31-35,41.
The constituent distribution,the wear resistance and fretting fatigue resistance(FFR) of electrospark strengthening layer on Ti811 titanium alloy were investigated.The results indicate that alloying layer could be produced by electrospark surface strengthening(ESS) on Ti811 titanium alloy with 0Cr18Ni9 electrode.Thus the hardness and wear resistance of Ti811 alloy are increased remarkably.But the hardness of 0Cr18Ni9 alloying layer is high with low ductility,so cracks easily initiate and extend into the bulk material quickly in the process of fretting fatigue(FF).Therefore the FFR of the titanium alloy treated by ESS is lower than that of the untreated specimen at elevated temperature.Shot peening(SP) can improve the FFR of the titanium alloy treated by ESS to the level of untreated specimen.
XU Cong-min, ZHANG Yao-heng, CHENG Guang-xu, ZHU Wen-sheng. Electrochemical Characteristic on Iron-oxidizing Bacteria Inducing Pitting Corrosion of 316L Stainless Steel[J]. Journal of Materials Engineering, 2006, 0(9): 36-41.
Pitting corrosion behavior of 316L stainless steel(SS) was investigated in the presence of aerobic IOB isolated from cooling water system in oil refinery by using polarization measurement,electrochemical impedance spectrum(EIS),scanning electron microscopy(SEM) and energy dispersive spectrum(EDS) analysis.The results showed that the corrosion potential(Ecorr),pitting potential(Epit) and polarization resistance(Rp) of 316L SS presented the variational trend of decrease-increase-decrease with the increase of immersion time;the corrosion rate of 316L SS in IOB solution was larger than that in sterile medium.The metabolic activity of IOB as well as the integrality and compactness of biofilm influenced pitting corrosion process,increased the corrosion damage of the passive film,accelerated the pitting corrosion of 316L SS.It is suggested from the present study that the effect of aerobic IOB on the pitting corrosion of 316L SS is highlighted.
YAO Ying-wu, YAO Su-wei, SONG Zhen-xing. Corrosion Behavior of Ni-W Alloy in NaCl Solution[J]. Journal of Materials Engineering, 2006, 0(9): 42-44,56.
Ni-W crystal alloy and Ni-W amorphous alloy were prepared by electroplating.The corrosion behavior of Ni-W alloy in 0.5mol/L NaCl solution was tested by the polarization curves and electrochemical impedance spectroscopy(EIS).The results show that the corrosion potential of Ni-W amorphous alloy in 0.5mol/L NaCl solution is more positive and the passive region is more obvious compared with Ni-W crystal alloy.The capactive loop of EIS of Ni-W amorphous alloy in 0.5mol/L NaCl solution is significantly larger than that of Ni-W crystal alloy and with the increasing of the immersion time a flat of passive membrane generated on the surface of Ni-W amorphous alloy and thus the variety of the capactive loop is not obvious.While the capactive loop of Ni-W crystal alloy becomes smaller as the increasing of the immersion time and the corruption of the surface becomes more serious.In conclusion,the anticorrosion ability of Ni-W amorphous alloy is much more excellent than that of Ni-W crystal alloy.
SUN Rong-lu, NIU Wei, LIU Lu-lu. Effects of Substrate Materials on Microstructure and Tribological Properties of NiCrBSiC Alloy Laser Clad Layer[J]. Journal of Materials Engineering, 2006, 0(9): 45-48.
Laser cladding of NiCrBSiC powders on 45 steel and TC4 alloy substrates was carried out.The microstructure of the laser clad layers was characterized using XRD,SEM and TEM.The microhardness and tribological properties of the laser clad layers were examined.The results showed that the microstructure,microhardness and tribological properties of the laser clad layers were closely related to kinds of substrates materials.The microstructure of the laser clad layer on 45 steel surface consisted of γ-Ni,Ni3B,Cr7C3 dendrites and CrB particles,and the microhardness of the laser clad layer was distributed within HV800-900.The microstructure of the laser clad layer on TC4 alloy surface consisted of γNi,Ni3B,TiC and TiB2 particles,and the microhardness of the laser clad layer was distributed within HV900-1100.The friction coefficient and mass loss rate of NiCrBSiC laser clad layer were lower on TC4 alloy than on 45 steel,respectively.
YUN Si-ning, WANG Xiao-li, SUN Xiao-liang. Microstructure and Dielectric Properties of Ba1-xSrxTi0.88Sn0.12O3 Ferroelectric Ceramics[J]. Journal of Materials Engineering, 2006, 0(9): 49-52.
Effects of Sr concentration and sintering temperature on microstructure and dielectric properties of Ba1-xSrxTi0.88Sn0.12O3(x=0.10,0.20,0.30,0.40 and 0.50)ceramics prepared by a high temperature solid-state technique were investigated.A preliminary structural XRD analysis of these compounds shows the formation of cubic perovskite structure.Detailed studies show that the dielectric properties of these compounds are closely related to Sr2+ and Sn4+ ions substituting for A-and B-site in Ba1-xSrxTi0.88Sn0.12O3 solid solutions ceramics.The dielectric properties of Ba1-xSrxTi0.88Sn0.12O3 ceramics decrease and the temperature of the maximum dielectric constant Tc shifts to lower temperature with increasing x values.A typical relaxation behavior is not observed,though all studied compositions exhibit the broad diffused phase transitions.
ZHANG Xiu-li, LIU Chang-li, SHA Gui-ying, LIU Lu. Negative Strain Rate Effect and Shear Deformation Band in Pipeline Steel[J]. Journal of Materials Engineering, 2006, 0(9): 53-56.
Dynamic impact compression experiments were conducted on column specimens of X70 pipeline steel after heat treatment using the Hopkinson pressure bar.The correlation between structural evolution and the dynamic stress-strain behavior was investigated.The results show that the martensite dominated microstructure of X70 pipeline steel after heat treatment is remarkably weakened and damaged under the strain rate lower than 2.5×103s-1.When the weakening by internal damage rate-dependent evolution is dominated,negative strain rate effect occurs.Furthermore,at the strain rate as high as 2.5×103s-1,shear deformation band forms,voids in and around the band appear,and the hardness of shear deformation band obviously increases.
LONG Jian-ping, WANG Ling, ZHANG Xiang-hui, CHANG Si-he. Impression Test Study on Adhesion Between Substrate and Diamond Film Deposited by Low Pressure Vapor Deposition[J]. Journal of Materials Engineering, 2006, 0(9): 57-63.
The diamond film was deposited on WC-6%Co(mass fraction) cemented carbide by DC arc discharged plasma chemical vapor deposition.Impression test was conducted by Rockwell hardness test,Rockwell superficial hardness test and Vickers hardness test.The scanning electron microscope was used to observe the impression microstructure and qualitalitively evaluate adhesion between diamond film and substrate.The result shows that the preferring hardness impression test is Rockwell superficial hardness test,test parameter including copped diamond depressor loading 441N.
