SUN Shi-qing. Thermal Stability and Magnetic Properties of High Chromium Iron Fibers[J]. Journal of Materials Engineering, 2007, 0(11): 3-6.
High chromium iron fibers were extracted from Cu-11Fe-4Cr in situ composite wires by nitric acid.The relation between structure and magnetic properties of micron and submicron high chromium iron fibers were investigated.The structure and morphology of samples were analyzed individually by XRD and SEM,and the magnetic properties of samples were measured by vibrating sample magnetometer(VSM).The thermal stability of high chromium iron fibers at different deformation strains was compared by TGA-DTA in air.The BCC structure of high chromium iron fibers is invariant when the fibers samples heated below 600℃ for 1 hour,and the saturation magnetization values of corresponding samples are always higher than 100 A·m2·kg-1.After the fibers heated at 800℃ for 1 hour,the saturation magnetization of samples decreases remarkably because of the transformation from ferromagnetic α-(Fe,Cr) solution to paramagnetic(Fe,Cr)2O3(Hexagonal structure).Micron and sub-micron high chromium iron fibers are obviously superior in thermal stability to micron polycrystalline iron fibers.With increasing deformation strains,the thermal stability of thinner fibers decreases.
GAO Zong-zhan, LIU Wei, YUE Zhu-feng, YANG Zhi-guo. Experimental Study of Fatigue Failure of Polymethyl Methacrylate for Edge Attachment Element[J]. Journal of Materials Engineering, 2007, 0(11): 7-10.
Tension and bending fatigue tests were carried out to investigate the fatigue behavior of polymethyl methacrylate for edge attachment element at different temperatures.Test results showed that the fatigue performances of the whole edge attachment assemble were extraordinary sensitive to experimental temperature.With increasing of temperature,the captive tension strength and tension fatigue strength decreased evidently.The captive bending strength and bending fatigue strength at uniform lifetime were maximal at lower temperature,and were minimum at room temperature.
YANG Zheng, TIAN Yun, LIU Guang-zu. Study on Recrystallization Behavior of MGH956 Alloy Cold Rolled Sheet[J]. Journal of Materials Engineering, 2007, 0(11): 11-14.
The recrystallization behavior and microstructure evolution of MGH956 alloy cold rolled sheet treated with high temperature were investigated.It was found that recrystallization would occurr in MGH956 cold rolled sheet when treated at high temperature as 1300℃,and the highly deformed tiny cold rolled grain would turn to coarse pancake grain at last.It was concluded that this kind of recrystalliztion is not secondary but primary recrystallization.Once the recrystallization stopped,microstructure would not change during further heat treatment time.
ZHANG Kun, DAI Sheng-long, HUANG Min, YAN Ming-gao. Effect of Long Time Thermal Exposure on Microstructures of Al-Cu-Mg-Ag Alloy[J]. Journal of Materials Engineering, 2007, 0(11): 15-19.
By means of transmission electron microscopy observation and energy spectrum analysis,microstructure changes of high-purity Al-Cu-Mg-Ag alloy which was originally on interrupted multi-step aged condition were investigated,when it exposed at various temperatures with or without stress.The results show that the morphology of predominant ageing precipitates Ω phase remained relatively stable after 100 hours exposure at 150℃ without stress bearing,while θ' phase continuously precipitated and slightly grew up.Increasing the exposure temperature to 200℃,pre-precipitated Ω phase and θ' phase markedly coarsened and part of metastable Ω phase tended to transforming to equilibrium θ phase.Particularly,a number of new precipitates of cubic σ phase occurred.Compared to above,an additionally constant stress of 200MPa on experimental alloy exposed at elevated temperature 200℃ promoted θ' phase and the smaller pre-precipitated Ω phase retrogressing into Al matrix,and accelerated coarsening of the larger Ω phase.Moreover,the equilibrium S phase precipitated at the expense of σ phase,which consumed over-saturated Cu and Mg elements in Al matrix and thus restrained σ phase precipitation.
WANG Shi-cai, LI Bao-xia, ZHANG Xiao-dong. Preparation of Polyvinylchloride/(vinyl chloride/ethyl acrylate)/(nanometer calcium carbonate) Composite Material and Its Properties[J]. Journal of Materials Engineering, 2007, 0(11): 20-23.
Poly(vinyl chloride)(PVC)/(vinyl chloride /ethyl acrylate)(VC/EA)/nanometer calcium carbonate(n-CaCO3)composite material was prepared in the basis of investigating nCaCO3 surface modification and the processing of(PVC)/(VC/EA)/ n-CaCO3 ternary-phase composite system,and its mechanical properties were also studied.The results showed that the dispersion of n-CaCO3filler in the matrix could obviously be improved by the twice dispersion forming process,in which the master batch was first prepared by dispersing the n-CaCO3 in the VC/EA copolymer,and then was processed with PVC;the general mechanical properties of prepared composite material were the best when the proportion of VC/EA to n-CaCO3 in the master batch was 2:3;the reinforcing effect of n-CaCO3 on PVC and good cooperation effect of n-CaCO3 and VC/EA on the toughness were obtained during the forming process,the impact strength of PVC/(VC/EA)/n-CaCO3 composite material was improved greatly,arriving at 38.2 kJ·m-2 when the proportion of PVC to the master batch((VC/EA)/n-CaCO3 =2:3) was 100:20,as 7.8 times as much as that of pure PVC(4.9 kJ·m2),at the same time the tensile strength of the composite material also arrived at 50.8MPa.
ZHAO Nai-ren, LI Jin-guo, LIU Jin-lai, WANG Zhi-hui, JIN Tao, SUN Xiao-feng, GUAN Heng-rong, YANG Hong-cai, HU Zhuang-qi. Solidification Interface in Growth of Single Crystal Superalloys by Seeding Technique[J]. Journal of Materials Engineering, 2007, 0(11): 24-27.
The evolution of solid/liquid interface during single crystal superalloy growth by seeding technique was investigated.The experiment results shows that the single crystal superalloy growth started from the top of seeds and the microstructure underwent the transformation from the unsteady self-organized to stable state.Solid/liquid interface changed from planar to cellular,then to dendrite.Primary arm spacing of cellular and dendrite crystal was modified by solidification parameters and initial morphology.Three types of adjusted model including competition selection,tip split and high order branching of dendrite can be identified.Fusion zone occurred between seeds and single crystal in starter growth.The composition of mushy zone depended on the chemical composition of seeds and the single crystal superalloy.
MA Yue, LI Wei, LIANG Zi-qing. Compressibility and Spring-back Behavior of Multi-axial Warp Knitting Fabric[J]. Journal of Materials Engineering, 2007, 0(11): 28-32.
Resin infusion under flexible tooling(RIFT) is a variant of vacuum-driven resin transfer molding in which the upper solid mould is replaced by the vacuum bag. As one of the tool face is flexible,there is no direct control over the thickness or fiber volume content of the final composite laminate which depend on the compressibility of the reinforcement under pressure.The compaction behavior of multi-axial warp knit reinforcement is investigated.It focus on the compaction time,layer of reinforcement,size of the bundle,reinforcement structure and the lay-up angle in the dry compaction test and the resin's lubrication effect on the reinforcement and the spring back behavior of reinforcement after resin pass over.Laminaes compressed to different level of target fiber volume fraction were sectioned through the thickness direction and their optical micrographs were used to analyze the real reason for compaction.
SHI Chun-ling, ZHANG Jian-xun. Effect of Low Temperature Heating on Properties and Microstructure of Aluminum Alloy 7150-T77[J]. Journal of Materials Engineering, 2007, 0(11): 33-36,86.
The heating test research aimed at 7150-T77 alloy is performed.The changes of that properties and microstructure under different heating temperatures have been observed.The test results show that,in company with increasing of heating temperature,material's conductivity,hardness and tensile property debase.When heating temperature greater than 175℃,material's conductivity,hardness and tensile property changes notability.When heating temperature greater than 185 ℃,material's conductivity,hardness and tensile property have changed to be disqualification.When heating temperature keep on heighten,material's conductivity,hardness and tensile property have changed more down.When heating temperature greater than 175℃,grain α has re-crystallized and phase η'grows up obviously.To ensure material property without greater drop during thermoforming,temperature part be heated shall be not high than 175℃.Conductivity reference value to determine the soften zone due to machining shall not more than 38%IACS.Syntheses thermoformingbility and behavioral against heating,7150-T77 thermoforming heating temperature shall be controlled in the range of 125-175℃.
LUO Feng-hua, LU Jing, CHEN Ming-jun, MENG Kang-long, LIU Lang-fei. Influence of Cu on the Martensitic and Magnetic Properties of Co41Ni33Al26 Alloy[J]. Journal of Materials Engineering, 2007, 0(11): 37-40,65.
Co-Ni-Al alloy is a promising ferromagnetic shape memory alloy for its good workability.The influence of Cu concentration x(x=3,5,8) on the martensitic transformation temperature and Curie point of Co41Ni33Al26 alloys were investigated by optical Metallography,DSC and VSM methods.The results show that martensitic transformation temperatures of Co41Ni33-xAl26Cux alloys decrease quickly with the increasing of Cu concentration x.In the range of x≤5%,1% Cu substitute Ni can decrease the martensitic transition temperature by 44K for alloys quenched from 1623K.Whereas the influence of x on Curie point isn't so strong,the decreasing in Curie point is only 3.6K for 1% increasing of Cu element.Comparing to Co41Ni33-xAl26Cux(x=0,3,5) alloys with L10 martensitic crystal structure,Co41Ni25Al26Cu8 with B2 crystal structure is easy to be magnetized and has the lowest magnetization saturation.
LU An-guo, QIU Tai, ZHOU Hong-qing, LIU Min, YANG Chun-hua, SHEN Chao-zhong. Effect of Borosilicate Glass on Microstructure and Properties of CaO-B2O3-SiO2 Glass-ceramics[J]. Journal of Materials Engineering, 2007, 0(11): 41-44.
CaO-B2O3-SiO2(CBS) glass-ceramic composites were prepared by adding borosilicate glass.The effects of borosilicate glass on the dielectric properties and coefficient of thermal expansion coefficient(CTE) were investigated.The relationships between properties and structures were studied by the aid of TG-DSC,XRD and SEM.The results show that the two kinds of glass are compatible with each other with the borosilicate glass content of 0-40%(mass fraction,the same below).The composite powder can be sintered at 850℃.The dielectric constant decreases with the increase of borosilicate glass content.The dielectirc constant can be adjusted in the range of 5.6-6.6.The CTE increases slowly when borosilicate glass content was less than 20% and increased rapidly with content of 20%-40%.The result is due to the formation of the new phaseα-SiO2 with low dielectric constant and high CTE.
HAN Zeng-xiang. Study on a Method for Measuring a-N Curves of Thermal Fatigue of Metals[J]. Journal of Materials Engineering, 2007, 0(11): 45-48,53.
A method was proposed to measure a-N cures of thermal fatigue of metals by measuring surface crack other than fracture crack with "single group of specimens" other than "multiple groups of specimens".The index of toughness necessary to measure surface crack length is determined by comparing the actual observation and measured crack length under the same surface toughness condition at the same cycles.The special operation method for measuring a-N curves with "single group of specimens" was also presented.A common rule of thermal fatigue of metals was analyzed and a method for fitting a-N curves was proposed.
TANG Xia, YANG Jie, LONG Sheng-ru, LIU Chun-li. Synthesis and Characterization of Copoly(Polyarylene Sulfide Ketone/Polyarylene Sulfide Amide)[J]. Journal of Materials Engineering, 2007, 0(11): 49-53.
Copoly(polyarylene sulfide keteone/polyarylene sulfide amide)was synthesized at normal pressure by the polycondensation of sodium sulfide(Na2S·xH2O) with N-(tetra-chlorphenyl)-parachlorobenzoyl amide and 4,4-difldibenzophenone(DFBP) in NMP.IR,UV spectra and H1-NMR analytical were carried out to characterize the structure of copolymers.Thermal properties of the copolymer were measured by means of DSC and TG.The results were showed that PASK/A retained excellent thermal stability and it had a bit of improvement of solubility to PASK.
CAO Lin-hong, XU Zuo, YAO Xi, ZHANG Rui-ming, LI Yan. Research on Preparation and Properties of Fluorine Substituted PMN-PT Ceramics[J]. Journal of Materials Engineering, 2007, 0(11): 54-57,61.
The fluorine substituted PMN-PT ceramics with pure perovskite phase were prepared by semichemical method,and the fluorine came from the raw material PbF2.The density of these ceramics increased with the increase of fluorine contents.For the pure PMN-PT ceramic,the grain size is larger,approximately 10 μm,and the peaks of dielectric constants and dielectric loss are sharper,and the peak value of dielectric constant is abnormally high,about 45000,and the P-E hysteresis loop is more rectangular,and the remnant polarization is about 30 μC/cm2,and the piezoelectric constant is about 420 pC/N.However,in the samples contained fluorine,the sample with 2% mole fraction of F has better microstructure and dielectric and piezoelectric properties.The grains size is about 2-3 μm, and the peak value of dielectric constants is about 30000,and the remnant polarization is about 30 μC/cm2,and the piezoelectric constant is about 380 pC/N.
YANG Hua, XU Bin-shi, DONG Shi-yun, DU Ling-zhong. Effect of Nano-particle on the Wear Performance of Composite Electro-brushing Coating in Oil with Sand and Strengthening Mechanics[J]. Journal of Materials Engineering, 2007, 0(11): 58-61.
A pure nickel coating and n-Al2O3/Ni composite coating were prepared.A comparative study was performed on the wear performance of the two coatings using T-11 wear tester with sand in oil.The experimental results showed that the wear performance of composite coating was 1.3-2.5 times of that of the pure nickel coating. From study of SEM,XRD and TEM,it was concluded that the contribution of the nano-particles to the wear performance of composite coating was associated to refining structure,dispersion in the coating and hindering propagation of microcracks.
YU Ping, WANG Lei-lei, MU Chun-ling, CUI wei, ZHANG Chang-qiao, XING Wen-guo. The Surface Appearance of Zn-Mg Alloy Coatings and Analysis of Corrosion Products in Na2SO4[J]. Journal of Materials Engineering, 2007, 0(11): 62-65.
The surface appearance and corrosion products of Zn-Mg alloy coatings with different content of Mg were analyzed by SEM and XRD.As a result,crystal particles of coatings were being diminished and structure tends to uniformity with growing Mg content.However,when the content of Mg was 2.5%,there will be Mg segregated in crystal interface.When the content of Mg was 3.0%,there will be more Mg segregated in crystal interface.That was approved by electronic probe.The baseline of diffraction was lifted and diffraction peak was broaden with growing Mg content.That was the content of non-crystal material in corrosion products grew,however,there was MgO in coating corrosion products when the content of Mg was 3.0%.It can be analyzed from the corrosion theory that the cathodic protection corrosion products were formatted by the segregation of Mg,the oxide film containing MgO was loose and cavernous and its compacting factor was 0.79.The reason that the ability to resist corrosion decreased was the chemical composition and structure of the film could not inhibit corrosion medium and corrosion.
GAO Yuan. Ceramic Process and Cr-Mo Infiltration of Carbon Steel for Improvement in Corrosion Resistance[J]. Journal of Materials Engineering, 2007, 0(11): 66-70,75.
A new technique that TiN coating is directly synthesized using plasma multi-infiltration on the surface of 20 steel was introduced.The structure formed by this techniques was solid solution diffusing layer and TiN deposition layer that was metallurgical bonding with matrix and couldn't produced desquamation.The surface hardness of infiltrating layer was 1600~3400HV.The results of X-ray diffraction showed that the infiltrating layer surface was pure-TiN and the strongest diffraction apex was on the(200) crystal face processing obvious preferred orientation.In addition on the 20 steel surface Mo content reached about 4% and Cr content reached 12% around using double glow plasma Cr-Mo infiltration,and then ultra-saturation carbonization made surface carbon content reach 2% above exceeding balancing carbon calculating values.Subsequently by quenching and low-tempering heat treatment the martensite matrix on which uniform,compact and dispersing carbide structure distributed was formed without eutectic ledeburite on the surface alloying layer.It was analyzed by X-ray diffraction that the types of layers' carbide were M23C6,M2C,and M6C,which dimension was 1-2μm and the surface hardness reached 1000HV around.In the 10% H2SO4,5% HCl and 3.5% NaCl water solution and H2S pregnant solution(H2S5-8g/L,NH3·H2O20g/L),the electrochemical corrosion experiments were carried out on the plasma multi-infiltration TiN and double glow plasma infiltration Cr samples.The results indicated that the corrosion resistance of multi-infiltration samples was increased 84,11.67,1.15 and 21.5 times than CrMo infiltration samples.
WANG Ying-min, DU Nan, CAI Li, LI He, CHENG Guo-an. Optical Property of ZnO Films Grown on Si Substrate by Plasma Enhanced Chemical Vapor Deposition[J]. Journal of Materials Engineering, 2007, 0(11): 71-75.
Reflection spectra of ZnO thin films grown at the different temperature by plasma enhanced chemical vapor deposition(PECVD) are investigated by Aquila 7000 films analysis system.The results show that growth temperature plays an important role to crystallographic properties of ZnO thin films.With increasing growth temperature,grains begin merge and grow up,the refractive index of ZnO thin films increase.When growth temperature reaches the temperature of 450℃,the maximum refractive index of ZnO thin films is 4.2,the absorption edge is around 380 nm,and the other absorption peak is observed at 520 nm.the location absorption peaks are conformity with the results of PL spectra of ZnO thin films,but growth temperature surpass 450℃,the quality of ZnO films become worse,refractive index of ZnO thin films decreases.
XI Yun-tao, LIU Dao-xin, HAN Dong, HAN Zeng-fu. Improvement of Erosion and Erosion-corrosion Resistance of 2Cr13 Stainless Steel by Low Temperature Plasma Nitriding[J]. Journal of Materials Engineering, 2007, 0(11): 76-81.
The erosion and erosion-corrosion behavior of 2Cr13 stainless steel influenced by nitriding treatment at 350℃ low temperature and 550℃ high temperature was studied using solid particle erosion tester and slurry erosion-corrosion apparatus.The mechanisms of erosion and erosion-corrosion resistance improvement by low temperature nitriding were investigated on the basis of microstructure analyzing,hardness testing and electrochemical impedance spectroscopy measurement.The results show that plasma nitriding treatment at both 350℃ and 550℃ can improve the erosion resistance of 2Cr13 stainless steel in the condition of dry erosion with small angle. Furthermore,the anti-erosion property of the steel nitrided by 350℃ low temperature is much more perfect than that by 550℃ nitriding.The erosion-corrosion rate of 2Cr13 stainless steel in 5% NaCl solution with 10% quartz sand was reduced by 96.7% in neutral environment and 87.4% in acidic environment by low temperature plasma nitriding,while the erosion-corrosion rate was increased 4.13 times in neutral environment and 0.49 times in acidic environment by normal nitriding.The 350℃ nitrided surface was dominated by both ε-Fe3N and a supersaturated nitrogen solid solution αN phases which had good chemical stability and high hardness properties.Therefore the corrosion,erosion and erosion-corrosion resistances of 2Cr13 martensitic stainless steel were considerably improved by the 350℃ nitriding treatment.When the nitriding temperature was above 550℃,the αN phase decomposed into α and CrN.The Cr composition in the nitrided surface was reduced and the corrosion resistance was decreased.In addition,because of the surface hardness of normal plasma nitriding was lower than that of low temperature nitriding,so the erosion resistance of the former was inferior to that of the latter and the erosion-corrosion properties was also poorer than the latter.
ZHANG Rong-fa, WANG Fang-yuan, HU Chang-yuan, LI Wenkui, XIANG Jun-huai, DUO Shu-wang, LI Ming-sheng, HE Xiang-ming. Research Progress in Sealing Treatment of Anodic Coatings Formed on Magnesium Alloys[J]. Journal of Materials Engineering, 2007, 0(11): 82-86.
Sealing is an effective method to further improve the corrosion resistance of anodic coatings formed on magnesium alloys.The main sealing methods include boiling water,chromate,silicate,phosphate,sol-gel and organic coating.Several sealing methods as above were reviewed comprehensively.In view of sealing technology underdeveloped on anodic coatings of magnesium alloys at present,the authors propose the research on the area should be reinforced in order to meet the industry application of anodizing on magnesium alloys.
