CHEN Er-fan, ZHANG Li. Preparation and Characterization of Different Topography Low Dimensional ZnO Whiskers[J]. Journal of Materials Engineering, 2008, 0(6): 1-4.
The different morphologies of high-quality ZnO whisker materials have been synthesized by thermal evaporation methods,which include wires,rods,and multiple morphologies.Effect of N2 feed rate,reaction temperature and reaction time on regular ratio,percent conversion and ratio of length and diameter is researched.The morphologies of the whiskers were characterized by SEM.The result shown that high-quality different morphologies of ZnO whiskers can be synthesized by thermal evaporation method in different conditions.The fractional pressure of zinc vapor plays an important role in forming the different morphologies of whiskers.Take the aging zinc powder as source material,heat preserve at 1000-1100℃ for less than 60 min and inlet high purity nitrogen at the rate of 0.2m3/h all the time,ZnO rods can be obtained.When the reaction time is longer,ZnO wires can be obtained.When the time of inletting high purity nitrogen is shorter,multiple morphologies can be obtained.
YIN Chang-ping, XIAO Jia-yu, ZENG Jing-cheng, LIU Jun, DAI Xiao-qing. Study on Rheological Behavior and Processing Window of Benzoxazine Resin for Resin Transfer Molding[J]. Journal of Materials Engineering, 2008, 0(6): 5-8,12.
Benzoxazine resin is a new ablative ring-opening polymerization phenolic resin for resin transfer molding(RTM).The rheological behavior of benzoxazine resin is studied with DSC analysis and viscosity experiments.A rheological model based on the dual-Arrhenius equation which is in good agreement with the results of experiments is established and used to simulate the rheological behavior of benzoxazine resin.The processing window of benzoxazine resin can be well determined based on the developed model.The rheological model is important for processing window forecast and processing parameter optimization.
HUANG Shi-song, SONG Wei-dong. Dynamic Tensile Experiments of Tungsten Alloys[J]. Journal of Materials Engineering, 2008, 0(6): 9-12.
Dynamic tension tests were conducted by employing SHTB to study the fracture behavior of 91%(mass fraction) tungsten alloy with three kinds of grain sizes of 2,5μm and 20μm.The dynamic mechanical properties of tungsten alloys under different strain rates were analyzed.The effects of grain size on the mechanical characteristics were discussed.By adopting SEM,the fracture section of the specimen after the dynamic tension tests were scanned and the fracture modes of the tungsten alloys under different strain rates were investigated.
TIAN Zhen-hui, TAN Hui-feng, DU Xing-wen. Fatigue Properties of Two Kinds of Rubber Composites[J]. Journal of Materials Engineering, 2008, 0(6): 13-15,20.
The fatigue damage properties of [0°] single-ply and [±20°] double-ply rubber composite under tension to tension loading were studied.The results show that the variation of the cycle strain of both kinds of material in the fatigue process under fatigue loading exhibits three stages which are corresponding to damage initiation,steady damage propagation and catastrophic failure respectively.The fatigue damage for the single-ply rubber composites is controlled by cord properties and for the double-ply rubber composite by matrix properties.The logarithmic fatigue life expressed by maximum stress follows a linear trend.The hysteretic loss keeps constant until the end of the fatigue life.The differences on hysteretic loss and the thermoconductivity result in differences on the surface temperature of different specimen.
LIAO Fang-ping, WANG Xiao-qun, WANG Hong-peng. The Exploration of Intelligent Temperature Control Material System Based on Thermoelectric Cooler[J]. Journal of Materials Engineering, 2008, 0(6): 16-20.
First,an intelligent temperature control material system based on thermoelectric cooler was presented.Effects of thermal environment around the material system,cooling mode,control algorithm,and working current were studied on the performance of the thermal control material system.Then,the appropriate working conditions were determined of this thermal control material system.Finally,the results showed that the intelligent temperature control material system can change its surface temperature according to the vibration of aimed temperature,exhibiting outstanding ability of intelligent temperature controlling.
LÜ Xiang-hong, YANG Yan-qing. Micro-analysis of Interfacial Reaction Diffusion in Ti Matrix Composite[J]. Journal of Materials Engineering, 2008, 0(6): 21-24,28.
SiC continuous fiberreinforced Ti matrix composites were fabricated and then heat-treated in vacuum under different conditions.The interfacial reaction and the formation of interfacial phases were studied by using of TEM,SEM,EDS and XRD methods.The results showed that there exists reaction diffusion at the interface of SiC fibers and Ti matrix,and the content fluctuation of reactive elements such as C,Ti and Si appears in interfacial reaction layers.The interfacial reaction products are identified as Ti3SiC2,TiC and Ti5Si3.Ti3SiC2 and Ti5Si3 single-phase zones come forth in turn adjacent to SiC fibers,and Ti5Si3 single-phase zone appears adjacent to Ti side,between which is TiC+Ti5Si3 double-phase zone.The formed interfacial phase sequences is to be SiC┃Ti3SiC2┃Ti5Si3┃TiC+Ti5Si3┃Ti from SiC fiber to Ti matrix.
ZHANG Wen-yu, LIU Xian-lan, CHEN Zhen-hua, XIA Wei-jun. Microstructure of AZ31 Magnesium Alloy Sheets During Asymmetric/Symmetric Rolling Procedure[J]. Journal of Materials Engineering, 2008, 0(6): 25-28.
The objective of this study is to investigate the evolvement of microstructure in AZ31 magnesium alloy sheets produced by asymmetric and symmetric rolling,which was analyzed by finite element method.The results indicated that the grain of AZ31 magnesium alloy sheets produced by asymmetric rolling was homogenous,which average grain size was 8.96 μm.While,the average grain size for the sheets produced by symmetric rolling was about 13.2 μm.Compared with that of the sheets produced by symmetric rolling,(0002) basal grain orientation of AZ31 magnesium alloy sheets produced by asymmetric rolling was obviously weakened.These could be owing to the intensive shear deformation induced by asymmetric rolling.
HE Cheng-hong, ZHANG Zuo-guang, LI Yu-bin, SUN Zhi-jie. Damage and Residual Flexural Properties of S-2/F46 Composites Under Low Velocity Impact[J]. Journal of Materials Engineering, 2008, 0(6): 29-32.
The residual flexural strength and modulus of unidirectional,cross-ply and quasi-isotropy S-2/F46 composites were investigated after the low velocity impact with different energies. The differences in damage modes and evolutions were analyzed combined with the damage morphology.The unidirectional composites show a mutation mode for the damage evolution or the reduction in flexural properties,while the cross-ply or quasi-isotropy composites show a multistage progressive mode.The flexural properties clearly degrade only when the structural integrity of composites is considerably damaged.The critical impact energy to initiate reduction in flexural property of unidirectional composites is the largest and that of cross-ply composites is the smallest.In addition,for angle-laminated composites,the reduction in flexural modulus is more significant than that in flexural strength.
JIA Yuan-zhi, WEI Zun-jie, MA Ming-zhen, ZENG Song-yan, WANG Wen-kui. Thermal Stability and Crystallization Process of FeCoNbSiBCu Bulk Metallic Glasses[J]. Journal of Materials Engineering, 2008, 0(6): 33-35,80.
Thermal stability and crystallization process of(Fe36Co36Nb4Si4.8B19.2)100-xCux(x=0,0.5,0.6,0.7) Bulk Metallic Glasses(BMGs) were studied by Differential Scanning Calorimetry(DSC) and in situ high temperature X Ray Diffraction(XRD).The minor addition of Cu significantly changes the crystallization process of the Fe36Co36Nb4Si4.8B19.2 BMG.The Cu free alloy shows single sharp exothermic peak during crystallization,whereas the Cu containing alloys exhibit four broad crystallization peaks.In situ high temperature X ray diffraction study shows that the bcc-FeCo precipitated from the amorphous precursor and transformed to bcc-Co7Fe3 at 930 K in the Cu containing alloys.The apparent crystallization active energy of bcc-Co7Fe3 is increased from 460.41kJ/mol to 545.69kJ/mol after Cu addition.The average grain size of the sample annealed at 840K for 17.5 minutes is 22.3nm calculated by Scherrer method.
CAO Da-shu, YAO Hong-yu, XUE Cai-jun, NIE Hong. Fracture Damage Analysis of a Nose Landing Gear[J]. Journal of Materials Engineering, 2008, 0(6): 36-39,56.
It is crucial for the aviation transportation safety to assure the landing gear’s structure reliability.The cause of the landing gear collapsing is studied through the fracture surface analysis and theoretic computation.The research indicated that the lower drag brace was buckled in compression and fractured by overload.When the tension load which the towbar applied in the aircraft surpassed 2.261×105 N,the lower drag brace would be buckled in compression.The research result will be value to make the specification for the aircraft ground safety technology.
DUAN Chun-zheng, WANG Min-jie, LI Shi-yan. Effect of Process Variables of Cryogenic Treatment on Mechanical Properties and Microstructure of W6Mo5Cr4V2 Steel[J]. Journal of Materials Engineering, 2008, 0(6): 40-43.
The repeated cryogenic treatment technique of W6Mo5Cr4V2 high speed steel was experimentally investigated using orthogonal experiment design,the effect of cryogenic treatment process variables on microstructure and macroscopic mechanical properties were analyzed,the fracture pattern and microstructure after repeated cryogenic treatment were studied.The results showed that after repeated cryogenic treatment,the mechanical properties were significantly improved,and the amount of fine dispersed carbide particles precipitated on martensitic dislocation meshworks was increased and their size and spacing got smaller.The effect of repeated cryogenic treatment is much better than that of single and long time cryogenic treatment.
HOU Yun-feng, XIA Tian-dong, ZHAO Wen-jun. Effect of Molten Aluminum Temperature on Microstructures of Al-Ti-C Master Alloys Prepared by Thermal Explosion Synthesis[J]. Journal of Materials Engineering, 2008, 0(6): 44-47.
Al-Ti-C master alloys were prepared by thermal explosion synthesis of Al-Ti-C preforms in molten aluminum,the influence of molten aluminum temperature on the microstructures of AlTi-C master alloy and grain refining performance were also investigated using XRD,SEM and grain refining tests.The results indicate that synthesized master alloy consist of Al,Al3Tiand TiC.Temperature of molten aluminum temperature have remarkable influence on size and distribution of second phase particles(Al3Ti,TiC) in synthesized products,the size of second phase particles was small and uniform distribution at low temperature of molten aluminum, however,some of aggregations of Al3Ti and TiC was observed at relatively high temperature of molten aluminum.Grain refining test show that the morphology of second phase particles has a great effect on grain refining performance.
LONG Zhi-zhou, HAN Min-fang, ZHANG Zuo-guang, WANG Ming-chao, LI Wei. Study on Micro-structure and Properties of Al2O3/SiC Ceramics by Pressureless Sintering in Air[J]. Journal of Materials Engineering, 2008, 0(6): 48-52,75.
The sintering behaviour in air of the Al2O3/SiC ceramics was studied,and the ceramics had achieved sintering densification successfully,the relative density of the sample adding 10% SiC(volume fraction,the same below) was 97.6%,which had a Vickers hardness of 14.45GPa.The effects of sintering temperature and SiC content on micro-structure,relative density,hardness and other properties were discussed; it could produce relatively dense ceramics at high temperature,but the specimens with more than 30% SiC would form a "sandwich" structure.The influence of the powder bed on the relative density was investigated,it showed that the powder bed could lower porosity of lower SiC content samples,and control oxidation effectively.
CHEN Mei-ling, ZHUANG Li, GAO Hong. Preparation and Performance Evaluation of Zinc Acrylate Compound Antifouling Paint[J]. Journal of Materials Engineering, 2008, 0(6): 53-56.
A new antifouling paint based on zinc acrylate resin and other assistant antifouling agent has been studied.The copper-releasing rate of paint has been checked and the antifouling performance has been investigated in the sea of Dalian Xinghai Bay.
LI He-sheng, CUI Jian-jun, LI Mu-sen. Effects of Iron-based Catalyst Structure on Diamond Synthesizing[J]. Journal of Materials Engineering, 2008, 0(6): 57-59.
The synthesizing diamond experiment was carried out at six-anvil high pressure apparatus with iron-based catalyst made by powder metallurgy.The microstructure of synthesized catalyst was investigated by means of optics microscope,scanning electron microscope and X-ray diffraction.The results indicate that the metallographic microstructure of catalyst is composed of coarse lathy original cementite and compact eutectic ledeburite.Much block graphite can be found in catalyst structure corresponding to poor quality and few yield of diamond.In general,it is very possible that the original cementite in catalyst is the direct carbon source of diamond. The process can be described as below: the graphite will firstly dissolve into the molten catalyst and form carbide with catalyst alloy at high temperature and high pressure.The carbon atom groups separate from cementite,then deposit on the growing diamond crystals to make them grow up.
QIU Yan-li, YANG Zhen-guo. Failure Analysis on Wear of Stopcock in Alkali Solution[J]. Journal of Materials Engineering, 2008, 0(6): 60-63.
The macro appearance,morphology and metallographic structure of plug valve made of stainless steel and leaked in alkali solution were observed by metallurgical microscope and Scanning Electron Microscope(SEM).Also,photoelectric direct reading spectrometer,Energy Dispersive Spectrometer(EDS),carbon and sulfur analyzer and NHO-analyzer were used to analyze chemical composition of materials and substances deposited on sealing area.The results showed that the failure of stopcock was corrosive wear and abrasive wear.The main cause leak of stopcock was that the selected plug material was not in accordance with the design and thus reduced properties of its anti-corrosion.Moreover,countermeasures for solving the problem have been tentatively put forward,and the analysis results provided the technological support to prevent the same accident.
JIA Bo, LI Chun-guang, LI Hai-yan. Influence of Recrystallization Layer at Surface on Fatigue Behaviors of Directionally Solidified DZ4 Superalloy[J]. Journal of Materials Engineering, 2008, 0(6): 64-67,71.
Board specimens of directionally solidified DZ4 superalloy after shot-peening were heated at 1220℃ for 4h to prepare recrystallized layer at the surface.Then fatigue experiments at 760℃ were carried out in order to research the effect of recrystallized layer on the fatigue properties of the board specimens.The results show that fatigue properties greatly decrease and the fatigue lives decrease with the increment of the depth of recrystallized layer.Fatigue cracks initiate from the recrystallized zone or the interface with matrix.Analogy calculation was carried out to simulate the damage evolutionary process with finite element analysis.The results show that stress field is changed because of the existence of recrystallized zone and stress at the interface between recrystallized zone and matrix is largest.So fatigue cracks initiate at the interface and propagate to the surface and the matrix.
FU Zhi-qiang, ZHOU Jia-bin, WANG Cheng-biao, TANG Chun-he, LIANG Tong-xiang, ZHAO Hong-sheng, ROBIN Jean-charles. Thermodynamic Analysis of Chemical Vapor Deposition Process for SiC/SiO2 Graded Composite Coating[J]. Journal of Materials Engineering, 2008, 0(6): 68-71.
SiC/SiO2 composite coating is an ideal coating system to greatly improve the oxidation resistance of graphite used in advanced high temperature gas-cooled reactor,but its optimum chemical vapor deposition process has not been reported.The influence of chemical vapor deposition process on the phase composition of SiC/SiO2 composite coating was studied with HSC-CHEMISTRY 4.1.It is found that the addition of enough hydrogen into carrier gas is necessary to obtain SiC/SiO2 composite coating without any impurities;the optimal deposition temperature is 1100-1200℃;and the optimal reactant concentration is: 1%-2% for SiCl4,the concentration of CH4 is same as that of SiCl4 for depositing SiC and the concentration of H2O is 2 times of that of SiCl4 for depositing SiO2;gradually changing the ratio of water vapor to CH4 for depositing graded SiC/SiO2 transition layers.
GUO Shao-yi, LI Xing-jun, YANG Qiu-he, YANG Jin-lin, MENG Fan-ying. Microstructure and Tribological Properties of Laser Clad WC-Ni/TiC Composite Coatings[J]. Journal of Materials Engineering, 2008, 0(6): 72-75.
A 7kW continuous wave CO2 laser was used to clad Ni-WC/TiC composite coatings on the surface of H13 steel substrates.The cross-section and surface morphologies of the coatings and wear tracks were observed with a JSM-5610 scanning microscope.The friction and properties were examined under dry sliding conditions using a WTM-1E type ball-on-disc machine.The wear mechanisms are discussed as well.The results showed that the WC-Ni/TiC composite coating has good wear resistance.The average surface microhardness of the coatings is HV1500 when the content of nano-TiC is 30%(mass fraction).The WC-Ni/TiC coatings’ wear resistance was a factor 8-15 times higher than that of unclad H13 steel.
DANG Xu-dan, XIAO Jun, LI Yong. Progress of Experimental Study on Mechanical Properties of X-cor Sandwich Structure[J]. Journal of Materials Engineering, 2008, 0(6): 76-80.
As an novel composite sandwich structure,X-cor sandwich structure has many advantages such as high stiffness,impact resistance,large damage tolerance so it can replace traditional honeycomb sandwich structure and become the main bearing loads structures of aircrafts.The outstanding advantage of X-cor sandwich structure is its programmable.Through changing the geometrical and physical parameters of face sheets,cores and enhanced materials the required mechanical properties are obtained.The progress of mechanical properties experiments about X-cor sandwich structure is introduced.Also the mechanical properties,damage mechanism and failure mode of X-cor sandwich structure under static and dynamic loads are discussed.In the end many kinds of problems needed lucubrated study about X-cor sandwich structure are proposed.
