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      20 January 2011, Volume 0 Issue 1 Previous Issue    Next Issue
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    Low Temperature Cure High Performance Composites
    CHEN Xiang-bao, ZHANG Bao-yan, LI Bin-tai
    2011, 0 (1): 1-6.  
    Abstract ( 446 ( PDF (1470KB)( 824 Citation
    The developments and applications of low temperature cure epoxy and high heat-resistance composite systems were reviewed.The curing agents,curing behavior,mechanical properties and applications of low temperature cure epoxy matrix composites were introduced,and a kind of low temperature cure high heat-resistance polyimide composite was also discussed.
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    Ground Recovery and Conservation of Property Degradation of ZnO-pigmented White Paints in Space
    WANG Xu-dong, GU Peng-fei, LI Chun-dong, HE Shi-yu, YANG De-zhuang
    2011, 0 (1): 7-10,16.  
    Abstract ( 292 ( PDF (499KB)( 329 Citation
    The large differences between the ground environment and space environment have important repercussions for the study of property degradation of ZnO-pigmented white paints.In order to conserve the optical degradation of ZnO-pigmented white paints in the ground experiments,S781 white paints were irradiated with 150-keV protons in a simulated space environment,and the irradiation-induced spectral reflectance change and solar absorptance change were studied in situ,in air,in vacuum,in Ar,and in liquid-nitrogen,respectively.The results show that the chemisorption of oxygen on ZnO causes the optical degradation to recover markedly when the irradiated samples are exposed to air.The vacuum,Ar,and liquid-nitrogen environments can suppress the chemisorption of ambient gases,and therefore conserve the optical degradation.Furthermore,the freeze-out effect of liquid-nitrogen is also useful for suppressing the recovery of optical degradation.
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    Construction of Model Evaluating Material Adaptability
    GUO Qi-wen, CAI Hong-nian, WANG Fu-chi, ZHANG Hong-mei
    2011, 0 (1): 11-16.  
    Abstract ( 307 ( PDF (1060KB)( 277 Citation
    Based on the construction of the evaluation indicator system for material adaptability,experienced experts were invited to evaluate the rationality of the evaluation indicator system and the relative importance(i.e.weight)of the evaluation factors using hierarchy analysis method.By computing and analyzing the experts’ evaluation results,all levels of the evaluation factors for the evaluation indicator system and the specific evaluation method for the material adaptability were decided.At the same time,the evaluation model for material adaptability was constructed.Several examples are shown that the evaluation model can factually generalize the most characters of the material adaptability and be exercisable.The evaluated results accord with the practical process.
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    Fracture Mechanism for 30CrMnSi Steel Based on Acoustic Emission Technology
    LONG Xian-hai, YANG Neng-jun, WANG Han-gong
    2011, 0 (1): 17-22.  
    Abstract ( 344 ( PDF (1407KB)( 620 Citation
    The whole physics process of ductile fracture in 30CrMnSi steel was investigated by the experiment of three-point bending specimen,which was monitored by acoustic emission system and the analysis of fracture by SEM and X-ray spectrometer.The results indicate that the whole process of the fracture includes there stages: the plastic deformation of crack tip,the crack pre-critical propagation and the crack critical propagation.The process of plastic deformation of crack tip is the formation and growth of cavity.The essential of crack pre-critical propagation is the connection of the dimples and the crack critical propagation is attributed to large-scale cleavage.There is a tendency to be more brittle during ductile fracture propagation for all stages.It is testified that acoustic emission technology is an efficient means to monitor the damage propagation for the high strength steel.
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    High Temperature Rheological Behavior of Aluminum Alloy Sheet 5050
    WANG Hong-feng, ZUO Dun-wen, HUANG Ming-min, CHEN Ming-he
    2011, 0 (1): 23-27.  
    Abstract ( 338 ( PDF (1553KB)( 248 Citation
    The warm tensile tests for 5050 aluminum alloy sheet metal were carried out at elevated temperature and different strain rates.The temperature was 303-673K and the strain rate was 0.001-0.1s-1.The warm tensile properties,relation between temperature,strain rate and the flow stress were studied.The results show that the flow stress declines with the increase of temperature and the decrease of strain rates.Elongation increases with the increase of temperature and the decrease of strain rates.Furthermore,constitutive equations under warm tension are obtained based on Hooke law and Grosman equation.
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    Polylactide/Montmorillonite Nanocomposites In-situ Polymerization and Characterization
    CHE Jing, QIN Fan, YANG Rong-jie
    2011, 0 (1): 28-32,37.  
    Abstract ( 465 ( PDF (1175KB)( 1008 Citation
    High molecular weight polylactide/montmorillonite nanocomposites were obtained through in-situ melt polycondensation method in which the montmorillonite(MMT) was added after dehydration and before the polycondensation.The results of XRD and TEM show that exfoliated nanocomposites are obtained when the addition of montmorillonite is 0.5%(mass fraction),and both intercalated and exfoliated structures are obtained when it is 1%.When the mass fractions of montmorillonite are 0.5% and 1%,the tensile strength,elongation at break and impact strength of the nanocomposites are better than those of pure polylactide(PLA).When they are higher,these mechanical properties become worse.SEM image of PLA-MMT0.5(the mass fraction of montmorillonite is 0.5%) shows a fracture toughness characterization.
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    Preparation and Acoustic Properties of Macroporous P(VAc-co-TAIC) Resin Beads
    SUN Wei-hong, YAN Xin, ZHU Xi, ZHOU Li-qing
    2011, 0 (1): 33-37.  
    Abstract ( 391 ( PDF (1226KB)( 399 Citation
    Macroporous P(VAc-co-TAIC) resin beads were prepared by suspension polymerization.The influences of the amount of crosslinking agent and porogen and bead diameter on pore volume and porosity were investigated.The results show that pore volume and porosity increase with increasing the bead diameter and content of porogen.The airborne acoustic absorption coefficients of the composites composed of PU/EP blend matrix and the resin beads were measured by using transfer function method,and the results show that the acoustic absorption coefficient of the matrix is improved with adding the resin beads.The results of underwater acoustic property test show that the underwater acoustic absorption coefficient of the matrix is evidently improved with adding 10%(mass fraction) of the resin beads,average acoustic absorption coefficient increases from 0.13 to 0.65,and the peak value increases from 0.29 to 0.94.
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    Synthesis of Carbon Nanofibers from Catalytic Decomposition of Methane by Fe2O3 in Thermal Plasma Jet
    BAO Wei-ren, ZHU Zi-ping, QIU Biao, WANG Jian-cheng, CHANG Li-ping, LÜ Yong-kang
    2011, 0 (1): 38-41,46.  
    Abstract ( 415 ( PDF (1248KB)( 305 Citation
    Carbon nanofibers(CNFs) from the decomposition of methane were prepared by thermal plasma under atmospheric pressure conditions,using Fe2O3 powder as catalyst,gas mixture of N2 and H2 as plasma working gas.The morphology structure,purity and crystallinity of CNFs products were characterized by SEM,TEM,TGA,and Raman spectrum.The results show that the products are cup-stacked like hollow CNFs with high crystallization as methane flow rate of 0.3m3/h,with increasing methane flow rate to 0.5m3/h,a mixture of bamboo-shaped carbon nanofibers and hollow tube with a large number of nano-particles is obtained and the purity of products decreases.
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    Experimental Study on Ex-situ Toughened Composite Laminates in Quasi-static Indentation Test
    XIE Zong-hong, ZHANG Lei, SU Ni, MA Hong-yi, YAN Li, CUI Hai-tao
    2011, 0 (1): 42-46.  
    Abstract ( 391 ( PDF (1303KB)( 280 Citation
    The "ex-situ" toughened and the non-toughened composite laminates were tested by using the quasi-static indentation(QSI) test method.The damage propagation and failure process of these two kinds of composite laminates were compared.The results show that the low-velocity impact damage resistance of composite laminates significantly increases due to the "ex-situ" toughening technique.According to the test results,the first load drop point on the contact force vs indenter displacement curve doesn’t correspond to the initiation of delamination.The existence of toughening layers could postpone the initiation of delaminations and also slow down the propagation of delaminations.However,at the maximum contact force,the delamination area in the "ex-situ" toughened laminates is larger than that in the non-toughened laminates.From the view of the back side of the penetrated specimens,the damage region on "ex-situ" toughened laminate is much more localized than that on the non-toughened laminate.For the latter,long and narrow fiber fractures were observed.
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    Carbide Evolution and Mo Depletion Law in Hastelloy C-276
    JIAO Shao-yang, ZHU Guan-ni, DONG Jian-xin, ZHANG Qing-quan
    2011, 0 (1): 47-52,56.  
    Abstract ( 460 ( PDF (1742KB)( 599 Citation
    The phase evolution and Mo mass fraction variation law when Hastelloy C-276 thermally aged at 550,750,800℃ for different time were studied.The results show that the carbide is precipitated along grain boundary for short aging time,and the Mo mass fraction firstly decreases to a minimum value about 6%(mass fraction) with carbide precipitation,then increases with aging time duration.Since the Mo content in nickel-based corrosion resistant alloy is vital to the alloy’s resistance ability,the carbide precipitation process and Mo mass fraction variation near grain boundary(GB) were simulated according to Thermo-Calc calculation,John-Mel transformations kinetics and Fick second diffusion law.The comparison results between the simulated and measured mass fraction of Mo are in good agreement,this signifies that the Mo mass fraction distribution near GB can be predicted by the model presented in this work.Based on simulation results,proper heat treatment conditions for this alloy can be proposed according to the requirement of Mo content in the service corrosion environments.
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    Manufacture Process Analysis of Heavy Die Block for Plastic Mould Steel
    LI Xiong, ZHANG Yu-long, XU Wei, BO Xin-tao
    2011, 0 (1): 53-56.  
    Abstract ( 352 ( PDF (1137KB)( 752 Citation
    Aiming at low qualification rate based on ultrasonic detection,the foreign and domestic manufacture processes for heavy die block of plastic mould steel were analyzed,and domestic current teeming,forging and heat treatment processes were perhaps imperfect.The results show that the vacuum top-pouring can make internal microstructure to be more compact contrasted with bottom-pouring and enhance ingot surface quality by supplementary means,to determine forging temperature should be according to internal quality of ingot and forging equipment tonnage,increasing internal deformation can cause healing of internal defects of ingot,whereas quick cooling after forging can make existing defects to become more serious.In view of poor effects of the dehydrogenation annealing of heavy die blocks,removal of hydrogen on the smelting and the teeming stages is more reasonable.It is conducive to preventing crack initiation and propagation for soft or stress relief annealing before quenching and at least two temperings after quenching.
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    Experimental Study on Eliminating and Preventing 20 Steel Thick-wall High Pressure Pipes from Strain Aging Embrittlement with Heat Treatment
    LI Meng-li, WANG Wei-qiang, LI Ai-ju, CUI Hao-xuan, CHEN Zhong-you
    2011, 0 (1): 57-63.  
    Abstract ( 319 ( PDF (1093KB)( 444 Citation
    Strain aging embrittlement of 20 steel thick-wall high pressure pipes is an important factor which has a great effect on the pipe long-term operating safety.Lots of heat treatments which were commonly used in engineering were adopted to eliminate or prevent the strain aging brittleness.The effect of the treatments was evaluated by Charpy V-notch impact absorption energy.Microstructure and fracture of specimen morphologies were observed by optical microscopy,scanning electron microscopy and transmission electron microscopy.Microstructure change of materials after different heat treatments was also discussed.The results show that the strain aging embrittlement comes into being in rolling process and is enhanced during the bend-forming process of the pipes.Different heat treatments have different effects to eliminate or prevent the strain aging brittleness,among which normalizing plus high temperature tempering is most effective.The deformation degree has a significant effect on recovering the impact properties of materials and whether aging or not after pre-deformation does not have significant effect on the heat treatment efficiency.
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    Numerical Simulation of Welding Deformation and Its Evolution for Welded Cylinder with Angle-inserting Elbow
    ZHANG Ke-rong, ZHANG Jian-xun, HUANG Si-luo, QIU Yi-qiang
    2011, 0 (1): 64-67,71.  
    Abstract ( 388 ( PDF (1153KB)( 336 Citation
    Based on finite element code,ANSYS software,finite element model of welding deformation of large thick-walled structure was performed,and the relative distance between elbow and thick-wall cylinder,the cylinder roundness variation and the deformation evolution of welded cylinder with angle-inserting elbow with thickness of 125mm were numerically analyzed.The results show that the displacement of elbow and the roundness on both sides of the cylinder have opposite changes at the stage of heating to the stage of cooling,moreover the cylinder roundness on the two ends of the cylinder have significant differences;a relatively large contraction appears eventually in the bottom of the groove;the deformation should be reduced by reducing the cooling rate in stage of initial 1-2h.
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    Experimental Study on CO2 Corrosion Resistant High Strength Pipeline Steels
    ZHANG Wei-wei, JI Ling-kang, CAI Qing-wu, WU Hui-bin
    2011, 0 (1): 68-71.  
    Abstract ( 285 ( PDF (833KB)( 285 Citation
    The CO2 corrosion resistance of pipeline steels could be enhanced by Cr proper addition and controlling the rolling procedure and the cooling temperature after finish rolling.The effects of the alloying component and rolling procedure parameters on mechanical properties and corrosion resistance were investigated for the pipeline steels.The results show that 0.55%(mass fraction)Cr addition,increasing the quantity of the cumulative billet rolling deformation on uncrystallized austenite phase and followed by cooling by 23℃/s,the steel can have the yield strength above 530MPa with a better CO2 corrosion resistance.
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    Modification of Polypropylene by Two Kinds of Core/Shell Composite Microspheres
    ZHAO Yan-sheng, MA De-peng, WU Feng-long, CHEN Kai, LIU Yong-mei, WEI Hua, WU Yong-xin
    2011, 0 (1): 72-75,80.  
    Abstract ( 327 ( PDF (1810KB)( 212 Citation
    Two kinds of core-shell composite microspheres with different interfacial interaction,polystyrene/MCM-41-g-γ-methacryloxypropyltrimethoxysilane(PS/MCM-41-g-MPS) and poly(styrene-γ-methacryloxypropyltrimethoxysilane)/MCM-41[P(St-MPS)/MCM-41],were added into polypropylene(PP) to improve its properties.The composite microspheres were prepared by using adsorption self-assembly method and co-condensation synthesis method,respectively.The effects of composite microspheres and their loading amount on the mechanical properties and crystallinity of PP composites were investigated.The results show that two kinds of composite microspheres can significantly improve the mechanical properties of PP.The tensile strength of two kinds of PP composites increases 12% and 13% of pure PP when the content of composite microspheres PS/MCM-41-g-MPS and P(St-MPS)/MCM-41 are 2% mass fraction;the impact strength reaches the maximum when the composite microspheres are 4% mass fraction,increases by 68% and 63%,respectively.The addition of composite microspheres also promote the formation of β crystal.However,there are some differences in mechanical properties and crystallinity of PP composites because the interfacial interaction of two composite microspheres added is different.SEM shows that core-shell interfacial interaction also directly affects their dispersion in the matrix and the toughening and reinforcing effect.
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    High Temperature Oxidation Resistance of AlYSi Coating by Arc Ion Plating
    ZHANG Peng-fei, LI Jian-ping, CAI Yan, LU Feng
    2011, 0 (1): 76-80.  
    Abstract ( 315 ( PDF (770KB)( 285 Citation
    The AlYSi coatings were deposited by arc ion plating on K465 superalloys.The high temperature oxidation behavior of K465 alloys with or without coating at 1100℃ was studied.By means of SEM,EDX and XRD,the surface and section of coating were analyzed.The results show that the coating is composed of β-NiAl phase,the Al2O3 protective scale is formed out of the coating and observably improves the high temperature oxidation resistance of K465 superalloys.
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    Effects of Zinc Bath Temperature on Microstructure of Hot Dip Galvanized 0.49%Si Reactive Steel
    KONG Gang, LIU Ren-bin, CHE Chun-shan, LU Jin-tang
    2011, 0 (1): 81-86.  
    Abstract ( 316 ( PDF (2305KB)( 383 Citation
    The hot dip galvanized samples of high silicon reactive steel(0.49%Si,mass fraction) were prepared by immersed in molten zinc bath at different temperatures(440,480,520,560,600℃) for different time(1,3,5,10min).The effects of zinc bath temperature and immersion time on the galvanized coatings were discussed.SEM/EDS results show that at 440℃ and 480℃,the coating is composed of thin δ layer and lumpy ζ phase.No Γ phase is found.The excessive growth of ζ produces an undesirable coating with excessive thickness,gray appearance and bad adhesion.The growth rate of coating obeys by interfacial reaction mechanism.At 520℃,the coating is composed of extremely thin Γ layer,compact δk layer and loose δp layer.The growth rate of coating is controlled by diffusion mechanism.At 560,600℃,the coating is a Γ layer and a compact δ layer.Some δ particles are dispersed in η layer.The growth rate of coating is controlled by diffusion mechanism,accompanying the dissolve of δ from coating into molten zinc bath.The optimized operating temperature for high temperature galvanizing should be controlled in the range of 520-560℃.
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    Effect of Temperature on H2S/CO2 Corrosion Behavior of Pipeline Steel
    YANG Jian-wei, ZHANG Jun, CAO Jian-ping, CHEN Chen, ZHANG Lei, DING Jin-hui, LU Min-xu
    2011, 0 (1): 87-91.  
    Abstract ( 423 ( PDF (1174KB)( 478 Citation
    Flowing solution environments containing H2S/CO2 were simulated in a high temperature and high pressure autoclave.Corrosion behavior of API-X60 pipeline steels was investigated with scanning electron microscopy(SEM) and X-ray diffraction methodology(XRD).Effects of temperature on corrosion rate and products were discussed.The results show that corrosion rate of X60 steel increases at the beginning and then decreases with temperature increasing,and localized corrosion turns into general corrosion obviously,but pitting is observed at high temperature.Mackinawite(FeS1-X) and FeS composite form as corrosion product in low-temperature condition,with temperature increasing the corrosion products were dominated by lamellar-type Mackinawite crystal and associated with a small amount of Pyrrhotite(Fe1-XS) crystal.However,Pyrrhotite crystal becomes more dominated at higher temperature region.Poor adhesion of corrosion scale leads to a lower covering rate at low temperature.Cathodic effects of scale promote the localized corrosion and a faster anode reaction rate and rapid development of pitting will be achieved without blocked effect.
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    Development and Application of Ductile Damage
    ZHANG Ding-fei, DAI Qing-wei, HU Yao-bo, QI Fu-gang, LI Peng-cheng
    2011, 0 (1): 92-98.  
    Abstract ( 441 ( PDF (1222KB)( 1339 Citation
    The mechanism of ductile damage and a general approach for the establishment of ductile damage model were reviewed.A variety of damage theories based on continuum mechanics,micromechanics,continuum damage mechanics were analyzed,as well as the intrinsic relationship among them was investigated.An overview of the effects of three-axis degrees,the strain path,and microstructure on ductile damage was carried on,especially the damage-plastic coupled analysis.The methods for studying ductile damage,such as the resistance measurement,statistics and quantitative characterization,finite element methods were described.The present problems in ductile damage investigation were analyzed,and the development direction was pointed out.
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