LI Jian-hua, FANG Fang, XI Tian-hui, CHEN Xiao, WU Kai-ming. Strengthening Mechanisms of Microalloyed 3.5Ni Steel[J]. Journal of Materials Engineering, 2010, 0(5): 1-4.
Strengthening mechanisms of microalloyed 3.5Ni steel were analyzed from the solution strengthening,precipitation strengthening and fine-grain strengthening.Their contribution to strengthening was also calculated.Results show that a lot of fine equaixed particles Nb(C,N),NbTi(C,N) and square particles TiN are uniformly precipitated in the matrix.These fine particles have precipitation strengthening effect and pinning effect on austenite grain boundaries,which hinder the growth of austenite grains.The calculated strength is in good agreement with the measured one.The strength of the tested steel is satisfied with National Standard CCS 1996 "Steel Seacraft Entering Level and Construction Standard" and has a surpass of 20%.
LIU Yu, LI Yi-min, XIA Qing-kun, HE Hao, ZHANG Jian-guang, XIAO Yan-fang. Micro Powder Injection Molding in Two-dimensional Rectangular Cavity Based on Granular Model[J]. Journal of Materials Engineering, 2010, 0(5): 5-9.
The process of micro powder injection molding for 2D rectangle cavity was studied based on granular model.This approach is proved feasible.The waveform effect is presented in flow of micro powder injection molding.There is relatively great contact force in center of the waveform.The frontal granular is held on the interface front and has no large lateral displacement.
TANG Ming-hua, LIU Zhi-yi, DENG Bin, HU Shuang-kai, LI Chun-yuan. Mechanism of Ultrafine Grain of Deformation Induced Ferrite Transformation at ZrC/Austenitic Interface[J]. Journal of Materials Engineering, 2010, 0(5): 10-14.
In order to deeply understand the mechanism of ultrafine grain of the low carbon steel obtaining ZrC particles,the effects of ZrC particles on ferrite grain refinement and basic characteristics of ferrite nucleating for this steel after deformation induced ferrite transformation at ZrC/austenitic interface were investigated by uniaxial hot compression simulation experiment.The results show that ZrC particles with definite size and suitable volume fraction dispersing in the matrix phase can hinder the movement of dislocation,form concentrated deformation zone and speed up the process of deformation induced ferrite transformation,thus increasing the nucleation rate of ferrite,resulting in ultrafine grain.The deformation induced ferrite transformation at ZrC/austenitic interface has shaped the unsaturated nature of nuclear position and the new α-phase has the characteristics of ultra-fine grain.In the strain conditions,the ferrite grains in the direction of 〈111〉 preferred orientation,a certain amount of small angle grain boundaries exist within ferrite grains,as the occurrence of ferrite dynamic recrystallization,ferrite further refinement,so the micro-mechanism of the testing steel is results of the role of the three,including the deformation induced ferrite transformation,ferrite dynamic recrystallization and dispersion strengthening of ZrC particle at the same time.
GUO Gui-bao, WANG Ya-xiong, KOU Sha-sha, HU Li-jie, AN Sheng-li. CO Electrochemical Sensors with PVDF-g-PS/PASA Electrolyte Membrane[J]. Journal of Materials Engineering, 2010, 0(5): 15-19,24.
A new method based on a solution graft technique was used to prepare poly(vinylidene fluoride) grafted styrene/acrylic acid sulfonated acid(PVDF-g-PS/PASA) electrolyte membrane.FTIR analysis results indicate that styrene and acrylic acid are grafted on the PVDF;the conductivity of PVDF-g-PS/PASA membrane is 0.0198S/cm at room temperature.The conductivity of the membrane changes slightly at a humidity range of 20%-80%.The weightlessness of PVDF-g-PS/PASA membrane heated to 40℃ is less than 1%,which indicates that keeping water ability is good.The linearity of the response curve is better for CO electro-chemical sensor prepared with the PVDF-g-PS/PASA electrolyte membrane.
GAO Zong-zhan, HE Xin-dang, JIANG Zhi-feng, YUE Zhu-feng. Reliability Analysis of Fatigue Life for Polymethyl Methacrylate with Edge Joint Structure[J]. Journal of Materials Engineering, 2010, 0(5): 20-24.
A low cycle fatigue life model was put forward based on bending experiment results of polymethyl methacrylate edge joint structures.Using this model,the reliability of the polymethyl methacrylate edge joint structure was analyzed by software MSC MARC.The material properties and fatigue load amplitudes were considered as random factors.The Monte-Carlo method and the forth moment method were utilized to get the fatigue life reliability of the polymethyl methacrylate edge joint structure under low cycle fatigue loading conditions.Comparing the two methods,it is found that the results are approximate with shorter analysis time for the forth moment method.Therefore,it is more suitable for reliability analysis of the polymethyl methacrylate edge joint structure.The parameter sensitivity was also analyzed with the mean value and standard deviation.The load amplitude is found to be the major factor.
CHEN Shan-hua, WU Yong, G. Schumacher. Effects of Helium Implantation on Microstructure and Mechanical Properties of Ti6Al4V Alloy[J]. Journal of Materials Engineering, 2010, 0(5): 25-29,33.
Ti6Al4V specimens were helium-ion implanted with constant fluence of 1×1017 ions/cm2 at 200keV within the temperature range from room temperature to 700℃.Nano-hardness and elastic modulus of the unimplanted and irradiated specimens were measured by means of the nano-indentation technique and analyzed using the Oliver-Pharr method.The indentation depth of all samples was 700 nm,which was comparable in magnitude to the ion range in the irradiated specimens.The phases in the surface layer of the Ti6Al4V specimens were investigated by the grazing incidence X-ray diffraction(GIXRD).The results indicate that with the implantation temperature increasing from room temperature to 600℃,the nano-hardness and elastic modulus of the irradiated specimens increase and decrease,respectively.The implantation at 700℃,however,caused softening and slight increase of the elastic modulus of the Ti6Al4V alloy.The hardening and reduction of the elastic modulus of the Ti6Al4V alloy under implantation conditions is related to the point defects and dispersed obstacles of β-precipitates.The softening and slight increase of elastic modulus of helium-irradiated Ti6Al4V at 700℃ might be a result of the coarsening of β-precipitates and the new γ-TiH phase formed in α-phase.
YANG Jin-ping, WANG Jing, WU Jian-qing. Influence of Nano-sized Leucite on Dental Porcelain Mechanical Properties[J]. Journal of Materials Engineering, 2010, 0(5): 30-33.
Nano-sized leucite powders were used as dispersed particles to improve the toughness and strength of low-temperature dental porcelain fused to metal.XRD and SEM were used to determine the phase composition and microstructure of nano-sized leucite in the sintered specimen.The effects of leucite content on the strength,hardness and fracture toughness of the sintered specimen were also investigated.Results show that the flexural strength,microhardness and fracture toughness increase with the content of nano-sized leucite.The dental porcelain containing 20%(mass fraction) of nano-sized leucite can obtain excellent mechanical property,which can match the Ni-Cr alloy very well in the thermal expansion coefficient.
YANG Cheng, CHENG Bo, TENG Le-jin, WANG Jin-peng. Self-assembled Gold-alkanethiols and Dielectric Properties of Au@S-R12/Polymer Composites[J]. Journal of Materials Engineering, 2010, 0(5): 34-37.
Self-assembled gold-dodecyl thiols nanoparticles were synthesized by simple aqueous solution method.The microstructure of Au@S-R12 was investigated the core-shell structure of gold-dodecyl thiols(denoted as Au@S-R12) by transmission electron microscope(TEM).The infrared spectra(IR) indicate the interlinkage of Au-core and alkanethiols-shell.The X-ray photoelectron spectroscope(XPS) records that the sulfur elements attach on the surface of Au.The thermal and optical properties were tested by thermal gravimetric analysis(TGA) and UV-VIS spectra,respectively.The Au@S-R12/polymer nanocomposites were prepared by tape-casting and hot-compression molding,and its dielectric properties were analyzed.The results indicate that the Au@S-R12/polymer nanocomposites have high dielectric constant,which owing to the alkanethiols have good dielectric barrier properties.
ZHANG Bo, LI Lei. Stress-fringe Information of Transparent Polycarbonate Plates[J]. Journal of Materials Engineering, 2010, 0(5): 38-40,46.
The heat-optical curve and stress-fringe information of polycarbonate(PC) materials were studied by adopting Tardy compensation method.Several problems were discussed based on the phenomenon of fringe order in different loading state.The results show that PC just needs small loads to provide the ideal fringe order.The loading time has big influence on the fringe order.There is only one regular fringe pattern in different loading direction of PC which produced by extrusion molding.The "ƒ" is obtained accurately,which is essential data to the calculation for the stress in digital photo elasticity method.
XU Huo-ping, LIU Hui-cong, ZHU Li-qun, LIU Jian-zhong, YE Xu-bin, HU Ben-run. Effects of Exposed Area on Corrosion Behavior of High Strength Aluminum Alloys in Salt Water[J]. Journal of Materials Engineering, 2010, 0(5): 41-46.
The corrosion characteristics of high strength aluminum alloys(2A12 and 7B04) with different exposed areas by 3.5%(mass fraction) NaCl salt water immersion test were investigated.The corrosion damage ratio was calculated through the binary image that obtained from image processing.The results indicate that the size of exposed area of the specimens can affect the pit corrosion of both 2A12 and 7B04 aluminum alloys in salt water immersion condition.No obvious pitting characteristic can be observed when the exposed area is smaller than a certain value,which is termed as the critical area of pitting corrosion.The pitting corrosion damage ratio improves with increase of exposed area.In addition,the difference of the critical areas between 2A12 and 7B04 aluminum alloys shows that the components of the aluminum alloys can affect the critical value.
PENG Zhou, HU Yong-gang, CHEN Guo-zhu, XIA Feng, WU Xi-wang, HU Shu-bing, WANG Ya-jun, XIAO Jian-zhong. Microstructures of TC4 Alloy Weld Joints by Electronic Beam Welding[J]. Journal of Materials Engineering, 2010, 0(5): 47-50,55.
The microstructures of TC4 weld beads by electronic beam welding(EBW) with different welding parameters were studied.The results show that the shapes of weld bead are different with the change of the weld parameters,but the phases in weld seam are almost the same.The microstructure gradient in weld seam is dependent on the shape of the weld bead.The larger the angle of seam is,the larger of the size gradient of martensite gets.The micro-hardness in weld bead is HV30-50 than that of the base material.The micro-hardness in the different shape of weld beads is consistent with the microstructures gradient in the weld bead.
YANG Zhong-zheng, ZHAO Shun-bo, XING Zhen-xian, LI Zhi-cheng, ZHANG Yue. Preparation of Bauxite-based Homogenized Mullite Grogs with Bauxite and Coal Gangue[J]. Journal of Materials Engineering, 2010, 0(5): 51-55.
Mixture was prepared by broken bauxite and coal gangue,adding a small quantity of active Al2O3,after milling,filtrating,drying,moloding,desiccating and calcining the mixture,the synthetical mullite grogs were produced,and the properties of synthetical mullite grogs were measured.Results show that the bauxite-based mullite grogs can be made by the method,sintering temperatures of specimens with and without MgO/CeO2 sintering aids are 1600℃ and 1700℃ separately,the mullite grogs with apparent porosity of <1.0% and 2.5%,bulk density of ≥2.75g·cm-3 and 2.87g·cm-3,and higher refracteriness-under-load,which indicates good hot strength properties.
WANG Zheng-an, WANG Ming-pu, YANG Wen-chao, ZHANG Qian, SHENG Xiao-fei, LI Zhou. Microstructure of As-cast and Homogenized 1973 Aluminum Alloy[J]. Journal of Materials Engineering, 2010, 0(5): 56-63.
The microstructure and the composition distribution of as-cast and homogenized 1973 alloy were studied by means of optical micrograph,scanning electron micrograph,X-ray diffractometry and DSC.The as-cast microstructure and the homogenizing temperatures of the alloy were determined.The results show that the as-cast microstructure is dendrite structure.It mainly consists of α-Al,MgZn2(η) phase and Al2CuMg(S) phase,and Al13(FeCu)4 phases were also observed.The η phase(MgZn2) dissolves aluminum and copper,and Al2CuMg phase shows solubility of zinc.The proper homogenizing process of this alloy is at 470℃ for 24h.After homogenization,η phase and S phase dissolve almost into the matrix,leaving a small amount Al13(FeCu)4 phase and Al7Cu2Fe phases only.A large number of Al3Zr phases with spheric shape were also observed,dispersing inside grains.
LIU Tong-gang, LIU Shu-jin, WU Jian, YANG Zhi-yi. Preparation and Purification of Carbon-coated Iron Nanoparticles by Arc-discharge Method[J]. Journal of Materials Engineering, 2010, 0(5): 64-67,71.
The carbon-coated iron nanoparticles were produced by a tungsten arc-discharge technique.The collected products were purified by a method of acid treatment and magnetic separation.The general morphology,phase composition and magnetic property of particles were characterized by TEM,XRD and vibration sample magnetometer(VSM).The results show that the purification method is effective to eliminate the uncoated particles and carbonaceous impurities from the products.The products after purification are almost exclusively iron nanocrystalline coated by onion shaped carbon.And the hysteresis curves of the particles also show an obvious increase of magnetism.
XUE Hang-yan, XIONG Jin-hui, HUANG Ji-hua, ZHANG Hua, ZHAO Xing-ke, WANG Zhi-ping. Microstructures of Composite Brazing Joints of Cf/SiC Composites and TC4 Using AgAlTi-C Filler Materials[J]. Journal of Materials Engineering, 2010, 0(5): 68-71.
Cf/SiC composite and TC4 were successfully joined by the mixed powders of Ag,Al,Ti and short carbon fibers under vacuum condition.The microstructure of the joints was investigated by X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.The results show that the maximum shear strength is 90.8MPa and the optimal parameter is brazing at 910℃ within 10min.The addition of short carbon fibers contributes a lot to the shear strength by alleviating the thermal stress of the joints and to the in-situ formation of TiC around the short carbon fibers.Ti element can improve filler metal’s wettability to Cf/SiC composite and restrain the oxidation of Al element.
ZHANG Zhen-ya, YU Hua-shun, WANG Shao-qing, WANG Hai-tao, MIN Guang-hui. High Strength ZK60 Magnesium Alloy Produced by Rapid Solidification/Powder Metallurgy Process[J]. Journal of Materials Engineering, 2010, 0(5): 72-77.
The microstructures and mechanical properties of ZK60(Mg-5.52Zn-0.33Zr,mass fraction/%) bulk alloys fabricated by rapid solidification/powder metallurgy process(RS/PM) and subsequently annealed at 200,300℃ for 1h were investigated.The results show that spherically shaped powder is elongated under severe shear stress during extrusion.Moreover,the refined primary grains gained by high cooling rate are broken into low angle subgrains/dislocation cells as well as lath subgrains,and the second phase nano-particles are distributed randomly along subgrain boundaries.By annealing at 200℃ for 1h,the dislocation density decreases,while the incomplete recrystallization happens in matrix.In contrast,when as-extruded bulk alloy is annealed at 300℃ for 1h,the complete crystallization takes place and fine equiaxed grains with average size of 2.5μm form.Simultaneous,more amount of β2′ phase are precipitated within grains.The yield strength and ductility to failure of as-extruded bulk alloy are up to 394MPa and 15.2%,respectively.With increase of annealing temperature,the ductility further enhances at a little sacrificed of strength,which exhibits excellent mechanical properties.
LI Guo-feng, ZHANG Xin-ming, ZHU Hang-fei. Effects of Minor Er and Y Addition to Al-Zn-Mg-Cu-Zr Alloy on Microstructures and Mechanical Properties[J]. Journal of Materials Engineering, 2010, 0(5): 78-82.
Effects of minor Er and Y addition to Al-Zn-Mg-Cu-Zr alloy on the microstructures and mechanical properties were investigated by means of optical microscopy(OM),scanning electron microscopy(SEM),transmission electron microscopy(TEM),hardness test and tensile properties measurement.The results indicate that minor Er and Y addition to the alloy evidently restrains the recrystallization of the tested alloys,delays the peak aging time and enhances the strengthening effect by aging.When the total addition of Er and Y is 0.4%(mass fraction),the σb,σ0.2 and δ of the tested alloy are 624.4,602.9MPa and 12.5%,which are greatly improved compared with the addition-free.
LIU Hai-tao, WU Chun-lian, ZHANG Jing-feng, LIN Shi-e, WENG Xue-jun, SHENG Zhen-hong. Coupling Activation Modification for Pyrophyllite Powder[J]. Journal of Materials Engineering, 2010, 0(5): 88-91.
The coupling activation modification as well as the coupling mechanism of the functionalized pyrophyllite powder from Taishun,Wenzhou,China,were investigated.The functionalization process changed the hydrophilic nature of the pyrophyllite powder into hydrophobic.The surface of pyrophyllite powder was modified by coating with N-(n-butyl)-3-aminopropyltrimethoxysilane(BAPTS) coupling agent and the pyrophyllite powder with activation index 100% was prepared.Activation index,viscosity and surface contact angle analyses were used to characterise the surface coupling modification for pyrophyllite powder and the activation mechanism was analysed and discussed.The relationships among activation index,viscosity,surface contact angle and the final coupling properties for pyrophyllite powder were investigated.The results indicate that the activation index arrives at 100% when the addition of coupling agent is 1.0% mass fraction.The maximum viscosity of the pyrophyllite-atolin system arrives at 85.78 mPa·s when the addition of coupling agent is 1.5% mass fraction.The maximum surface contact angle on water arrives at 75° when the addition of coupling agent is 2.0% mass fraction.The coupling modification can provide a useful method of preparation of the activation pyrophyllite powder with the achievement of a fine and a strong adhesion level.
ZHAO Liang, WANG Jing-feng, ZHU Xue-chun, HAO Xiao-dong, ZHONG Min, PAN Fu-sheng. Influences of Modifier on Microstructure Uniformity of High-silicon Aluminum Alloy Standard Sample[J]. Journal of Materials Engineering, 2010, 0(5): 92-95,100.
The influences of Al-Sr,Al-P,Cu-P modifier on microstructure uniformity of high-silicon(22%,mass fraction) aluminum alloy standard samples were investigated by using the optical microscopy and X-ray diffraction.The results show that the microstructure uniformity of the standard sample without modifying is poor because the primary crystal silicon is large sheet and gathers into cluster.After adding Al-Sr modifier,the microstructure of the standard sample is shown to be unsatisfactory uniformity because the primary crystal silicon gets a certain degree of refinement,but the eutectic silicon has a high degree of branching.After adding Al-P and Cu-P modifier,the microstructure of the standard sample is homogeneous because new AlP phase making the primary crystal silicon change from the board sheet into a small polygonal particle and amount increases when the eutectic silicon is reduced.In addition,it can be founded that after adding Cu-P modifier the improvement is more remarkable and the uniformity of organizations is better.Also the uniformity of the composition meets the requirement for standard sample even tested by the traditional range-method.This work can provide new criterion and reference for preparation of standard sample of high-silicon aluminum alloy according to the microstructure uniformity.
YANG Fei, KONG Fan-tao, CHEN Yu-yong, XIAO Shu-long. Manufacture and Present Status of TiAl Alloy Sheet[J]. Journal of Materials Engineering, 2010, 0(5): 96-100.
Two methods and researching status of manufacturing TiAl based alloy sheet,including ingot metallurgy and powder metallurgy,were briefly reviewed.And the fabrication processes and materials properties of cast rolling,tape casting and physical vapor deposition were introduced.Meanwhile,the prospects for these techniques were also described.
