CHEN Yu-yong, YANG Fei, KONG Fan-tao, XIAO Shu-long. Effect of Sintering Temperature on Microstructure and Properties of TiAl Bulk Materials[J]. Journal of Materials Engineering, 2010, 0(4): 1-4.
The effect of the sintering temperature(750-1050℃) on microstructure and properties of bulk materials prepared by mechanical alloying(MA) and spark plasma sintering(SPS) was investigated.XRD patterns showed that the bulk material which is consolidated densely was mainly composed of γ-TiAl and α2-Ti3Al.SEM and TEM observed the microstructures.When the sintering temperature was 950℃,the as-milled powders were densely consolidated into bulk material with a nearly 100% density,and the yield strength can reach 2106MPa.The density of bulk material changed a little and the yield strength decreased when the sintering temperature was above 950℃.
LIU Guang-ming, KANG Yong-lin, CHEN Ji-ping, FENG Yue-xue, ZHOU Jian, TENG Hua-xiang. Microstructure and Mechanical Property of 390MPa Grade Ti+Nb Bearing High Strength Ultra-low Carbon Bake Hardening Sheet Steel[J]. Journal of Materials Engineering, 2010, 0(4): 5-9.
Hot rolling,cold rolling and continuous annealing of Ti+Nb+B bearing high strength ultra-low carbon bake hardening steel were studied.The results show that the developed high strength ultra-low carbon bake hardening steel possesses superior formability and excellent bake hardenability.The ratio of the yield strength to tensile strength is 0.536.The bake hardening value is 44MPa.The tensile strength of the developed steel is 394MPa,which meets the requirements of the 390MPa grade high strength ultra-low carbon bake hardening steel.It has been shown from the results of physicochemical phase analysis that most of the alloying element B in the high strength ultra-low carbon bake hardening steel exists in the form of interstitial solid solution and plays a role in the solid solution strengthening besides 2mg/kg BN precipitation.
LI Cheng-lü, PAN Qing-lin, LIU Xiao-yan, HE Yun-bin, LI Wen-bin. Hot Compression Deformation and Processing Maps of 2124 Aluminum Alloy[J]. Journal of Materials Engineering, 2010, 0(4): 10-14.
The flow stress behavior of 2124 aluminum alloy during hot compression deformation was studied by thermal simulation test,under the conditions of the strain rate range of 0.1-10s-1 and the temperature range from 340-500℃.The results showed that the flow behavior of 2124 aluminum alloy was described by the hyperbolic sine constitutive equation,and an activation energy of 170.13kJ/mol was calculated.The processing maps were calculated and analyzed according to the dynamic materials model.The instability zones of flow behavior can be recognized by the maps.The optimum processing parameters of hot deformation in the range of this experiment can also be attained by the maps,which the hot temperature was around 450℃ and the strain rate is 0.01-0.1s-1.
MA Feng, ZONG Xue-gang, CHEN Ming-hui, LI Yong-chao. Preparation and Properties of Lauric Acid/SiO2 Phase Change Energy Storage Composite Materials[J]. Journal of Materials Engineering, 2010, 0(4): 15-17.
Lauric acid was imbedded into the net of silicon dioxide(SiO2) to preparing lauric acid/silicon dioxide phase change energy storage composite material by sol-gel method.In such a composite,lauric acid served as a latent heat storage material and silicon dioxide acts as a supporting material.The structure,morphology,and thermal performance of the composite were characterized by IR,SEM and DSC.The results showed that the composite containing 69.1%(mass fraction) lauric acid had a melting temperature of 43.1℃ and latent heat of 104.64J/g.Lauric acid was uniformly imbedded into the net of silicon dioxide without melted leakage from the composite.The thermal conductivity of the phase change material could be improved effectively by using silicon dioxide as a supporting material.
CHEN Guo-sheng, WANG Qing-zeng, ZHANG Wan-liang, LI Wei, WANG Zi-xing, LIU Feng-jun, WANG Shi-pu. Microstructure and Properties of Fine Grain GH4169 Alloy Bar Rolled by Continuous Roller[J]. Journal of Materials Engineering, 2010, 0(4): 18-21.
The newly imported high-alloy steel continuous rolling line which was the first line in our country was introduced for about two years,and the microstructure and properties of GH4169 alloy hot-rolling bars produced by this line were studied,and the sizes of such bars were in the range of 20-55mm.Comparing with the traditional horizontal roller,this continuous rolling technology was tend to get finer grain bar and the grains were more uniform and the δ-phase distributed properly.The specifications range,the grain size can be controlled about 10 grade and the process was more stable.So the rolled bars possess more stable and comprehensive properties.Meanwhile,the size precision and production rate of the products are both increased markedly.
ZHENG Wei-hong, LIN Mo-zhou, CHENG Jin-shu, TANG Li-ying. Effect of Fluorine on Structure and Crystallization of Lithium Aluminosilicate Glasses[J]. Journal of Materials Engineering, 2010, 0(4): 22-25,32.
The fluorine was introduced to the lithium aluminosilicate glasses for decreasing viscosity and melting temperature for float process.The influence on the structure and crystallization of lithium aluminosilicate glasses with various fluorine dopants was investigated by means of Raman spectroscopy,XRD and high temperature viscosity test.The results showed that the addition of fluorine induced the average Si(Al)O4 ring structures shifted progressively to smaller rings and the degree of connection of Si(Al)O4 tetrahedron was decreased in the three-dimensional glass network.The viscosity of initial glasses was effectively decreased with fluorine dopants.When the addition of fluorine increased from 0.00mol to 0.28mol,the crystallinity of specimens was increased but the main phase was still β-spodumene.Moreover,the Raman spectra showed that the anatase precipitated as minor phase after heat-treated.
HUA Xing-yan, ZHAO Pei-zhong, ZHU Jin-hua, WANG Yuan-sheng. Plastic Deformation Modes of Rigid PU/ER Interpenetrating Polymer Networks Foams Under Static Loading[J]. Journal of Materials Engineering, 2010, 0(4): 26-32.
A series of rigid polyurethane/epoxy resin interpenetrating polymer networks(PU/ER IPN) foams were prepared by a simultaneous polymerization technique.The chemical structure and morphology of these foams were investigated by fourier transform infrared(FTIR) spectroscopy and scanning electron microscopy(SEM).The compression responses of the IPN foams are anisotropic.Compression in the rising direction yields a typical three-stage stress-strain response of foams,and the prominent features are strain-softening and deformation localization.Compression in the transversal direction gives rise to a monotonously increasing stress-strain curve without strain-softening and always produces uniformly distributed deformation.The results show that the compression behaviors of the IPN foams are sensitive to the strain rates and ER contents.A theoretical model,which could describe deformation localization of the foams,is referenced to calculate the deformation band parameters,and correlates well with experiments.The compression deformation mechanism of the IPN foams is analyzed by this model.
LI Xiu-hui, WU Jiang-yu, YANG Peng, GUO San-wei. Study on Thermal/Salty Tolerance of SAP-based Water Swelling Rubber[J]. Journal of Materials Engineering, 2010, 0(4): 33-35,41.
SuperAbsorbent polymer(SAP) of P(AANa/AMPS/DMDAAC) was synthesized by inverse suspension polymerization.Hydrophobic modification of this SAP was performed via in-situ polymerization with introduced monomer n-butyl acrylate and acrylic acid.Water swellable rubber(WSR) was prepared using modified SAP,NBR,reinforcing agent and other additives.The swelling ratio in mass of WSR in water or in aqueous solutions of diverse inorganic salt was measured.The effects of ionic concentration and temperature on the swelling ratio were investigated and thermogravimetric analysis(TGA) of swollen rubber was performed.The results showed that the swelling ratio of WSR remarkably decreased with higher ions valence and with increasing concentration of salt solution.The highest swelling rate was obtained at 120℃,both in water and in 0.9%NaCl solution.A water loss plateau of swollen WSR was observed with 0.9% NaCl solution as the Absorbent solution.
MA Shi-ning, LUO Lin, LIU Qian, QIU Ji. Microstructure and Properties of 7A52 Aluminum Alloy Welded Joints of Different Medium Aqueous Vapor Plasma Arc[J]. Journal of Materials Engineering, 2010, 0(4): 36-41.
Pure water and different medium aqueous plasma arc were used to weld 7A52 aluminum alloy plate of 6mm thickness.The arc force of different medium aqueous plasma arc was measured.The microstructure and properties of 7A52 aluminum alloy welded joints of different medium aqueous vapor plasma arc were studied.The results indicate the higher the acetone,the larger the arc force and the deeper the penetration.The oxidizability of the plasma arc is decreased with the increasing of the acetone,which can improve the quality of the welded joint.The aqueous vapor with acetone concentration of 40%(volume fraction)presents the optimum properties and microstructure for the welded joints.There was harden and soften zone in the HAZ(heat affected zone),which is mainly related to the arc force,the conducting speed of arc heat,the conversion of the strengthen phase and the aging state.
CAI Wen, HU Jie, XIANG Wei-dong, ZHAO Yin-sheng, WANG Xiao-ming, HUANG Wen-hai. Solvothermal Synthesis of Flower-like Copper Indium Sulphide Microcrystalline and Its Characterization[J]. Journal of Materials Engineering, 2010, 0(4): 42-45.
Copper indium sulphide products were synthesized via a mild solvothermal approach(at 200℃ for 12h)involving CuCl2·2H2O as the copper source,InCl3 as the indium source,thiourea as the sulfur source,N,N-dimethylformamide,ethylene glycol,ethanol and polyethylene glycol-300 as the reaction medium respectively.Morphology,structure,and phase constituents of the as-prepared CuInS2 products were characterized by X-ray diffraction(XRD),X-ray photo-electron spectroscopy(XPS) and field-emission scanning electron microscopy(FESEM).The results showed that the CuInS2 products synthesized in dimethylformamide(DMF),ethylene glycol,ethanol and polyethylene glycol-300 respectively had flower-like morphology composed of large numbers of nanoplates and the thickness of CuInS2 nanoplates was found to vary from 100-200nm.A possible formation mechanism was put forward and discussed based on the experimental results.
WU Hong-li, ZHANG Wei. Effect of Silica on Percolation Characteristics of Carbon Black/Epoxy Resin Composites[J]. Journal of Materials Engineering, 2010, 0(4): 46-50.
Carbon black(CB)-silica-epoxy resin composites were prepared by solvent process and the percolation characteristics of obtained composites were also investigated.When the volume fraction of CB is lower than 15.5%,the electrical conductivity of composites can be described by classic percolation theory.The percolation threshold is found to be 14.7%,which is in good agreement with predicted value.When the volume fraction of CB is over 15.5%,the electrical conductivity of composites deviates significantly from predicted values.This can be ascribed to the generation of CB aggregates via hydrogen bonds and Van Der Waals forces.The formation of aggregates disobeys one of the hypotheses of percolation theory that conductive particles must be mono-dispersed,and results in the deviation of experimental data from theoretical values.The decreasing of silica content lowers the efficiency of its volume excluded effect to CB particles and consequently facilitates the formation of CB aggregates,which is supported by scanning electron microscope(SEM) analyses and molecular simulation results.
LUO Ye, LI Yan. Acoustical Studies of Natural Fiber Reinforced Composites[J]. Journal of Materials Engineering, 2010, 0(4): 51-54.
The natural fiber reinforced composite laminates and honeycomb sandwich structures were prepared by hot press.Acoustic properties were tested with the aid of two-microphone impedance tube and compared with synthetic fiber reinforced composite counterparts.The results showed that natural fiber reinforced composites laminates had better acoustic properties than their synthetic counterparts,but still failed to reach the requirements as acoustic materials.Proper materials design is needed to further improve the acoustic properties of natural fiber reinforced composite laminates.While,natural fiber based honeycomb sandwich structures had good acoustical properties,with its peak sound Absorption coefficient approaching 0.4,and thus could be used as acoustic materials.
LU Lei, ZHANG An-nan, ZOU Jin, CHEN Zhi-bao, HU Qiang. Study on Corrosion Resistance of High-strength and High-conductivity Copper Alloy[J]. Journal of Materials Engineering, 2010, 0(4): 55-58.
The corrosive behavior of Cu-Ag and Cu-Fe-P was investigated with acetic acid salt spray(AASS) and electrochemical test.The corrosion morphology was studied by means of SEM and the corrosion products were analyzed by means of EDS and XRD.The results indicate that Cu-Fe-P has the better corrosion resistance compare with Cu-Ag.With the grain refining effect of Fe and the deoxygenation effect of P,the additions of Fe and P to the copper can improve the strength,conductivity and corrosion resistance of alloy by refine grain and clean the alloy.
DENG Jian-qi, ZHANG Xiu-qing, SHANG Shu-zhen, ZHAO Zu-xin, YE Yi-fu. Structural Evolution Characteristics of Cu-10Cr-0.4Zr In-situ Composites[J]. Journal of Materials Engineering, 2010, 0(4): 59-62,68.
The Cu-10Cr alloy,Cu-10Cr-0.4Zr alloy and the in-situ composite based on the alloys were prepared.Microstructures of as-cast,structural evolution characteristics of Cu-10Cr-0.4Zr in-situ composites were investigated.The results showed that the addition of 0.4%(mass fraction)Zr in the Cu-10%Cr gave birth to smaller as-cast Cr dendrites,their diameters were reduced from 15-80μm to 10-20μm;the EDS quantitative analysis of as-cast Cu-10Cr-0.4Zr alloy showed that the Zr-rich phase should be Cu5Zr;with the increasing of drawing strains,the spacings among the β-Cr phases decreased gradually and the thickness of β-Cr phases decreased rapidly,the β-Cr phases were constrained to fold and twist,particularly at η=6.2,the thickness reached 250-350nm;at η=6.2,the predicted strength using Hall-Petch equation was 1037MPa,which was good agreement with the observed strength 1089MPa.
CHEN Ke, LI Zi-quan, LIU Jin-song, YANG Ji-nian, SUN Ying-di, BIAN Song-gang. Effects of Ba Addition on Microstructure and Properties of In-situ Synthesized Mg2Si/Mg-Zn-Si Composite[J]. Journal of Materials Engineering, 2010, 0(4): 63-68.
Effects of 0.1%-2.0%(mass fraction) Ba addition on the microstructure and tensile properties of Mg2Si /Mg-Zn-Si composites with high Si content were investigated.The results indicate that,the morphology of primary Mg2Si in the composites changes from large dendrite to fine polygonal with the increasing Ba content,and its average size sharply decreases until addition of Ba 1.0% and then slowly increases.The average size of eutectic Mg2Si also shows the same change trend.Numerous tiny BaMg2Si2 particles act as the heterogeneous nucleation substrate for primary Mg2Si.It is also found that BaMg2Si2 size in Mg2Si is obviously coarsened as addition of Ba surpasses 1.0%,which is responsible for over modification.Refined Mg2Si particles dispersion-strengthen the composite and results in the improvement of ductility.The proper Ba content is a key factor to obtain effectively refined Mg2Si and enhanced composite.
CAI Lu, WANG Zhang-zhong, ZHAO Xiu-ming, HE Xian-cong. Deformation Strengthening Effect of Microalloyed Steel for Cold Heading Bolt[J]. Journal of Materials Engineering, 2010, 0(4): 69-71.
According to manufactured procedures of the MFT8 bolt for microalloyed steel,the deformation strengthening effects for raw material,cold-drawing and aging treatment were studied,respectively.The strain hardening exponents and mechanical properties were compared,and the effects of microstructure on material properties were analyzed.The results show that deformation strengthening effect of the MFT8 bolt for microalloyed steel is obvious.It still possesses favorable deformation strengthening performance after aging treatment to insure the use safety of bolts.The standard of all kinds of mechanical properties of deformation strengthening bolt has reached 8.8 grade,therefore,the MFT8 for microalloyed steel can substitute quenched and tempered steel for manufacturing high-strengthened bolts.
DING Wei, JIANG Hai-tao, TANG Di, TIAN Zhi-qiang, YIN An-min. Mechanical Property and Retained Austenite of Low-Si TRIP Steel[J]. Journal of Materials Engineering, 2010, 0(4): 72-75,80.
The mechanical properties and work-hardening characteristics of A low-Si TRIP steel were researched by the tensile test.The change of structure before and after tensile test,especially the change of retained austenite,were studied with scanning electron microscope(SEM),X-ray diffraction(XRD),electron back-scattered diffraction(EBSD) and transmission electron microscope(TEM).The results show that the low-Si TRIP steel has good mechanical properties,no yield point and possess of low yield ratio,meantime it has better extensibility and homogeneous strain than DP steel.Retained austenite distribution also affects the stability of the low-Si TRIP steel,retained austenite in ferrite grain still exists after the tensile test.
WU Feng-qiu, ZHANG Bao-fa, JIANG Hai, LI Dong-sheng. Influence of Silicon Dioxide Powder with Different Granularity on Carbon/Carbon Composite Oxidation Protective Coating[J]. Journal of Materials Engineering, 2010, 0(4): 76-80.
The influence of protective coatings formed of micron silicon dioxide(SiO2) and nanometer silicon dioxide(SiO2) on the anti-oxidation property of carbon/carbon composite,with the content of 6%,12%,18% and 24% percent respectively was investigated.And the components and the morphologies of protective coatings fore-and-aft-oxidation were also discussed contrastively with the X-ray diffraction(XRD) and the scanning electron microscope(SEM).The results showed that as the content of micron SiO2 increasing,ratios of oxidized mass loss on the carbon/carbon composite protective coating reduced first,then increased,whose best content was 18% with the ratio of oxidized mass loss of 0.38%.While as the content of nanometer SiO2 increasing,ratios of mass loss increased all along.The lowest ratio of oxidized mass loss was 2.88% with the smallest content of 6%.
WANG Li-juan, LI Jian. Preparation of Wood-based Electromagnetic Shielding Composite by Electroless Nickel Plating on Birch Veneer Pretreated with NaBH4[J]. Journal of Materials Engineering, 2010, 0(4): 81-85.
Electromagnetic shielding composite was prepared by direct electroless nickel plating on birch veneer as substrate treated with NaBH4.The effects of NaBH4 concentration and immersion time,plating time,and NaOH concentration on the surface resistivity of composites were investigated.The morphology and structure of composites obtained under NaBH4 pretreatment and Pd colloid activation were analyzed and compared by using scanning electron microscope(SEM) and X-ray diffraction(XRD).And the electromagnetic shielding effectiveness(ESE) and adhesion strength of the layer were measured by spectrum analyzer and vertical pulling method,respectively.The results show that the surface resistivity of the composite is lower than 150mΩ/cm2,and the ESE is higher than 60dB in the frequencies from 9kHz to 1.5GHz,which the composite was obtained under the conditions that the substrate was treated in 3g/L NaBH4 solution containing 4g/LNaOH for 5-10min,and then plated for 20min.The ESE of composite obtained under NaBH4 treatment is higher than that with Pd colloid.It was observed from morphologies that the layers deposited by the two methods are all uniform,continuous and compact,and the whole wood surface is covered,which has obvious metallic sheen.XRD analysis indicates that the layer obtained by using NaBH4 pretreatment is thicker and has better crystalline structure,and high physic adhesion between the layer and wood.Adhesion strength measurement shows that the layers deposited by the two methods are bonded with wood firmly.
HE Mei-feng, LIU Lei, WU Ya-ting, TIAN Fu-ying, HU Wen-bin. Microstructure and Corrosion Properties of AZ91D Magnesium Alloy by Molten Salt Bath Treatment[J]. Journal of Materials Engineering, 2010, 0(4): 86-88,93.
A dense and adhesive multilayer coating on AZ91D magnesium was successfully obtained by AlCl3-NaCl molten salt bath treatment.The corrosion resistance of AZ91D alloy without and with coating by a multilayer Mg-Al intermetallic compound was evaluated by open circuit potential and electrochemical impedance spectroscopy measurements in 3.5%(mass fraction)NaCl solutions.A multilayer structure was observed in the alloyed coating at 400℃ with 8h treatment time.The inner layer of alloyed coating presents network feature,while the outer layer of alloyed coating is composed of cubical shape particles.The coated sample shows higher open circuit potential than the uncoated one.The coating polarization resistance value of the coated sample is ten times greater.
WEI Zhi-qiang, YAN Xiao-yan, WANG Bao-zhen, ZHU Lin, YANG Xiao-hong, YAN Peng-xun. Study on Preparation and Oxidization Resistance of NiO Encapsulated Ni Nanoparticles[J]. Journal of Materials Engineering, 2010, 0(4): 89-93.
NiO encapsulated Ni nanoparticles were prepared by direct current arc plasma method and subsequently passivation.The chemical composition,morphology,crystal microstructure,particle size and oxidization resistance of the product were analyzed using the high-resolution transmission electron microscopy(HRTEM),X-ray diffraction(XRD),transmission electron microscopy(TEM) and the corresponding selected-area electron diffraction(SAED),thermogravimetric analyzer(TGA) and diffirential scanning calorimeter(DSC).The results showed that the NiO encapsulated Ni nanoparticles with clear core-shell structure.The core is consisted of particles of Ni,while the shell is consisted of NiO.The particle size of the samples was homogeneously distributed with spherical shape and well dispersed,the particle size distribution ranging from 20-70nm with the average particle size about 44nm and the thickness of the shell 5-8nm.The core-shell structure can prevent Ni nanoparticles from oxidation and agglomeration.
YANG Lu, ZHOU Yuan-kang, LI Yi, ZHU Xiang-ning, ZHANG Yong-jie. Influence of Nano-palygorskite Lubricant Additive on Friction and Wear Properties of HT200 Friction Components[J]. Journal of Materials Engineering, 2010, 0(4): 94-98.
The palygorskite nanoparticles were prepared,and the palygorskite nanoparticles were mixed in base oil 150N as lubricant additive.The friction-wear properties of HT200 friction components lubricated with pure 150N base oil and the lubricant with palygorskite nanoparticles additive were investigated on the MMU-10G abrasive-wear tester.The analysis of worn surfaces employed SEM and metallographic microscope.Meanwhile,the mechanism which causes the change of friction-wear properties of HT200 lubicated with different lubricants was discussed,the elemental compositions of the worm surfaces were characterized by EDX.The results show that the palygorskite nanoparticles modified with KH550 during ball milling have fine dispersing.The lubricant with nano-palygorskite additive causes the self-repairing film formation of worn surface,and the wear mass loss of HT200 friction components decreases observably as high as 25.2%,the friction coefficient declines about 32.3%.
