GENG Yu, SONG Yan, ZHONG Ming, LI Peng, GUO Quan-gui, LIU Lang. Investigation of Preparation and Electrochemical Performance of Phenolic Resin Based Activated Carbon Cloth[J]. Journal of Materials Engineering, 2011, 0(10): 1-4.
Phenolic resin based Activated Carbon Cloths(ACCs) were prepared by carbon dioxide activation treatment,and were used as electrodes of supercapacitors.The pore structure and the electrochemical properties of the resultant ACCs were investigated by means of nitrogen adsorption,AC impedance and constant current discharge techniques.The relationship of pore structure and the electrochemical performance in 1M(CH2CH3)3CH3NBF4/PC were discussed in details.Results showed that the specific capacitance of the samples increase with the BET surface area,and the specific capacitance of ACC4 reached 135 F·g-1 at current density of 50mA·g-1.Besides,the contribution to the specific capacitance from micropores decreases while that of from mesopores increases with the increase of the current density.The conductivity of the sample decreased and the ESR increased with the enhancement of activation degree.
YUAN Xun-feng, DING Yu-tian. Phase-field Method of Multi-dendrites Growth Under Forced Flow[J]. Journal of Materials Engineering, 2011, 0(10): 5-10.
The phase-field model coupled with the concentration field,temperature field and flow field is used to simulate multi-dendrites growth of Ni-Cu alloys in a forced flow.The morphologies of dendrites and distribution of temperature and concentration is studied.The result shows that fluid flow alters the local heat and concentration transfer at the solidification front,and effects the growth of the dentrite.Because of the undercooled melt flushing,the temperature and concentration of the upstream dendrite are low,making the tip of dendrite to grow faster;the temperature and the concentration of the downstream dendrite are high,making the tip of dendrite to grow slow.Due to the flow and multi-dendrites affect each other the crystal grows into asymmetrical dentrite morphologies.In addition,the fluid flow changed the preferred growth direction of dendrite which is not parallel to flow,making it tilts towards the upstream direction.
LI Jing-jing, XU Ling-wei, CHEN Jian-zhong, ZHANG Neng-hui. Flexoelectric Analysis of Single-stranded DNA Biofilm on Chip[J]. Journal of Materials Engineering, 2011, 0(10): 11-14.
Based on nonlinear Poisson-Boltzmann equation(NLPB) and flexoelectric theory of liquid crystal thin films,with the help of Fogolari’s correct formula,a nonlinear multiscale relation among single-stranded DNA(ssDNA) molecule structure feature,salt solution concentration and biofilm electrostatic potential,chip macroscopic deformation is formulated.The flexoelectric coefficient is obtained by curve fitting based on existing experimental data.The linear and nonlinear predictions for biofilm electrostatic potential and chip deformation are compared to validate the present nonlinear multiscale relation.The influences of DNA fragment length,packing density on chip deformation are also investigated.The results show that chip deformation increase with the enhancement of DNA fragment length and packing density.
WANG Jian-wei, SHANG Xin-chun, LÜ Guo-cai. Molecular Dynamics Simulation of Vacancy Concentration on Irradiation Cascades Damage Effects in bcc-Fe[J]. Journal of Materials Engineering, 2011, 0(10): 15-18.
The neutron irradiation on metal materials could generate various defects which are caused by displacement cascades.The displacement cascades of neutron irradiation with various vacancy concentrations in bcc-Fe are simulated by three-dimensional molecular dynamics method.The simulation results show that a large number of vacancies and self interstitial atoms(SIAs) clusters would appear for the case of 0% vacancy concentration and 5keV primary knock-on atom energy.The number of point defect NF reached to peak value 1632 after 0.5ps.It will decrease sequently and the number of point defect will go stable value 60 after 10 ps.The existence of pre-vacancy defects would accelerate the defect annihilation in the cascade process.The further simulation indicated that the defect annihilation is the faster in the case of the higher prevacancy concentration.These results could be useful for describing some mechanism of microcosmic failure for structural steels components in nuclear reactors.
SHEN Zheng-xiang, LÜ Zhong-jie, TONG Yi, HUANG Feng-lei. A Thermodynamic Analysis on Mixing Progress of Molten Aluminum and Water[J]. Journal of Materials Engineering, 2011, 0(10): 19-22.
In order to understand the explosion character of molten aluminum and water,a preliminary analysis has been taken to their premixing stage by laws of thermodynamics.The analysis results show that,under standard conditions the specific energy of water and corresponding energy conversion raised,with increasing of the mass ratio of molten aluminum and water in the premixing stage.However,while the initial conditions or the temperature of melt being altered,the variation trend of specific energy of water and energy conversion still keeps constant.Even when mass ratio of molten aluminum and water mAl/mw is approach to 0 and melt is in form of drop,the energy conversion η can be linear relation with mAl/mw.
CAO La-mei, LI Xiang-hui, CHEN Jing-yang, XUE Ming, ZHANG Yong. Influence of Solution Heat Treatment Temperature on the Microstructure of the Third Generation Ni-based Single Crystal Superalloy DD10[J]. Journal of Materials Engineering, 2011, 0(10): 23-27.
The effects of solution heat treatment temperature on the microstructures,dendritic segregation and microstructural stability of the third generation Ni-based single crystal superalloy DD10 were investigated by using technics such as SEM(Scanning Electron Microscope),OM(Optical Microscope) and EDS(Energy Dispersive X-ray Spectroscope) analysis.The results indicate that the eutectic is almost disappeared at 1290℃/6h.Limited amount of microporosities are observed in the interdendritic region at 1330℃/6h and initial melting appears while the solution heat treatment temperature is up to 1340℃.The dendritic segregation degree is decreased after solution heat treatment at both 1320℃ and 1330℃.The results of long-term thermal exposure at 1095℃ indicate that the microstructural stability of DD10 is improved and the amount of TCP phase is decreased significantly after solution heat treatment at 1330℃ due to lower dendritic segregation.Furthermore,the morphology,size and volume fraction of γ′ precipitates are not influenced by solution heat treatment temperature.
XU Fei, CHEN Li, GONG Shui-li, YANG Jing, ZHAO Xiao-ming, HE En-guang. Weld Appearance and Mechanical Properties of Aluminum-lithium Alloy by YAG-MIG Hybrid Welding[J]. Journal of Materials Engineering, 2011, 0(10): 28-32,37.
The weld appearance and mechanical properties of 5A90 Al-Li alloy sheet by YAG-MIG hybrid welding are studied.The results show that the weld appearance(collapse,undercut,and so on) of 5A90 alloy by laser beam welding(LBW) is improved by YAG-MIG hybrid welding significantly.And the maximal tolerant gap of the hybrid welding could reach to about 1.0mm.The major microstructure characteristics of joint by hybrid welding are fine-grained layer and the equaixed grain in most of welded seam,which are similar to the joint by LBW.Compared with the latter,the microstructure of the former tends to coarse,and the range of the columnar crystals zone is prone to decrease.The microhardness of welded seam by hybrid welding(83.57HV0.2) is lower than that by LBW(95.65HV0.2),but the uniformity of the former is better than that of the latter.The ultimate strength and the elongations after fracture of the joint by hybrid welding are lower than that by LBW.The fracture of the tensile samples always occur near the fusion zone,and the tensile fracture presents mixed rupture of brittle and ductile,which is mainly composed of the former.Therefore,if the combined mechanical properties of joint by hybrid welding meet the operation requirements,it should be improved by heat treatment after welding,and it also should develop a better filler wire matched with the base metal.
CHEN Shui-sheng, LIN Jian-ping. An Analytical Model to Predict the Effect of Weld Location on Tensile Behaviors of Tailor Welded Blanks[J]. Journal of Materials Engineering, 2011, 0(10): 33-37.
Entire elongation and weld line movement were defined to evaluate tensile properties of tailor-welded blanks(TWBs) respectively.Under different initial weld locations,the analytical models were developed to evaluate the entire elongation and the weld line movement of TWBs.To validate the analytical models,finite element analysis(FEA) and experiments were performed to investigate the influences of initial weld locations on the entire elongation and the weld line movement.The results show that the analytical results have a good agreement with the experiment and the simulation results.The entire elongation and the weld line movement increase linearly with the weld line moving closer to the stronger side of TWBs,and the variation rate depends on the material parameters and thickness of base sheets.Based on the proposed analytical model,the major influencing factors of the entire elongation and the weld line movement as well as their effects on tensile properties of TWBs can be revealed.
ZHANG Chuan-chen, HUANG Ji-hua, ZHANG Tian-cang, JI Ya-juan. Effects of Amplitude on Joint Microstructure and the Interfacial Atomic Concentration Distribution of Linear Friction Welding[J]. Journal of Materials Engineering, 2011, 0(10): 38-41,46.
With changing amplitude,the dissimilar titanium alloys of TC11 and TC17 were welded by linear friction welding and the welded joint temperature was measured.The microstructure of the joints and flash were examined using an optical microscope(OPM) and a scanning electron microscope(SEM).Electron probe microanalysis(EPMA) was also carried out to determine the elemental diffusion in and around the interface region.The results showed that with increasing amplitude,the weld heat input increased and the flash length increased.During the linear friction welding,the temperature around the interface exceeded 1100℃,above βtransition temperature.Dynamic recrystallization is operative on weld center and the flash during linear friction welding.There still exists an evident interface after welding and no mechanical mixture was found at the interface.Compared to the parent material,the microstructure in the weld and flash center was refined.The size of the recrystal grain on both sides of the welded joints decreased with increasing amplitude.Elemental diffusion layers exist on the interface and with the amplitude increased the thickness of the diffusion layer become wider.
ZHAO Jia-qi, YANG Wei-guang, NAN Hai, WU Guo-qing. Effects of Hot Isostatic Pressing Treatment Parameters on Mechanical Properties of ZTC4 Casting Titanium Alloy[J]. Journal of Materials Engineering, 2011, 0(10): 42-46.
In order to obtain the best mechanical properties of ZTC4 alloy casting,effects of hot isostatic pressing treatment parameters(temperature,time and pressure) on microstructure of ZTC4 casting titanium alloy were investigated systemically.The results show that the room temperature tension and bend properties are obviously affected by the hot isostatic pressing treatment parameters,especially the elongation of ZTC4 alloy,but the impact property is affected slightly.The casting show the best mechanical properties when they are HIP at 920℃ for 2h with the pressure of 125MPa,by consideration of all the conditions.
LI Hong-mei, SUN Da-qian, DONG Peng, WANG Wen-quan, YIN Shi-qiang. Study on Laser Welding of Dissimilar Materials Between TiNi Shape Memory Alloy/Stainless Steel[J]. Journal of Materials Engineering, 2011, 0(10): 47-51,57.
TiNi shape memory alloy and stainless steel wires were butt joined by laser welding with pure Ni interlayer.Microstructures and properties of joints with and without Ni interlayer were analyzed and discussed.The results showed that microstructures and properties of the joint with Ni interlayer were improved significantly compared with the joint without Ni interlayer.More γ-Fe phase and less intermetallic compounds such as TiFe2,TiCr2 were formed in the joint with Ni interlayer,which led to the decrease of weld microhardness and increase of joint strength.The joint strength without Ni interlayer was only 187MPa and the corresponding fracture surface exhibited a typical brittle feature.Using the Ni interlayer elevated joint strength to 372MPa and changed the joint fracture mode from pure brittle feature to mixture of cleavage and dimples.
WANG Li-xian, GUO Qiang, GUO Chun-ying, PAN Guo-liang. Study of the Method for Coloring on Aluminum Anodic Oxide Films by Coupling Reaction[J]. Journal of Materials Engineering, 2011, 0(10): 52-57.
Aluminum anodic oxide(AAO) films can be colored by a color pigment phenylazo-N,N-diphenyl propanicn diamide derivative,which is made through coupling reaction between N,N-diphenylpropanediamide derivatives and phenyl diazonium chloride on the AAO films.The process parameters for making AAO colored films and the property of AAO colored films were studied.The results show that the AAO films made under experiment conditions,ampere density 3-3.5A/dm2(AC),reaction temperature 25-35℃ for 1h,can be colored easily;The coupling conditions for coloring the AAO films are reaction temperature 5-10℃ and reaction time 5-20min,piperidine as catalysis,DMF as solvent.The test results shown that the thickness of colored films is >20μm.The study on protection properties shown that the colored films has permanent protective property: the grade of 168h salt spray test is 10;there is no change of the films during the 240h alternate hygrothermal test;the eroded grade of continuous 730 days nature-exposure test is 10.So the colored films has permanent protective and decoration properties.
LIU Guang-qing, ZHANG Shuai, LIU Meng-yin, LI De-jun. Effect of Modulation Period on Structure and Mechanical Properties of ReB2/TaN Nanoscale Nanomultilayers[J]. Journal of Materials Engineering, 2011, 0(10): 58-60,65.
A series of nanoscale ReB2/TaN multilayered coatings were prepared by ultra-high vacuum RF magnetron sputtering system at 20℃.The influence of modulation period(Λ) on the microstructure and mechanical properties of the film was investigated by SEM,XRD,surface profiler and nano-indenter.The results showed that ReB2 and TaN layers exhibited hexagonal structure in films.ReB2/TaN multilayers have superhard effects with a modulation period from 8-12nm.At Λ=9.6nm,ReB2/TaN multilayered possessed the highest hardness of 28.8GPa and modulus of 345.9GPa with lower residual stress.
TANG Tian-shun, GONG Jian-xun, XIAO Yi-feng, LU De-bin. The Effect of SiC on the Properties of Self-shielded Open Arc High Chromium Hardfacing Alloys[J]. Journal of Materials Engineering, 2011, 0(10): 61-65.
A series of high chromium alloys were prepared by the method of self-shielded open arc flux-cored wire hardfacing with varying SiC content.The effect of SiC on the properties was investigated by optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM) and wet sand rubber wear tests.The results show that SiC has a significant effect on the shape,the size,the volume fraction and the distribution of the microstructure.With the addition of 0%-4%(mass fraction,the same below) SiC into a flux-core wire,the grains were refined and the volume fraction of the eutectic(α-Fe+M3(C,B)) increased,which made abrasion resistance descended.As SiC content rose up to 8%,the primary M23C6 grains appeared and the abrasion resistance was improved.But when it was higher than 12%,excessive Si atoms provided by the decomposition of SiC can inversely intensify the graphitization tendency of weld beads,which inhibited the formation of primary M23C6 phases.The analysis of worn morphology indicates that the wear mode of material removal changes from the dominant clipping to the combined scoring and clipping with the increasing addition of SiC powders.
MAO Wei-guo, CHEN Qiang, ZHANG Bin, WAN Jie. Investigations of Elastic Modulus and Hardness of Air Plasma Sprayed Thermal Barrier Coatings by Nanoindentation Method[J]. Journal of Materials Engineering, 2011, 0(10): 66-71,77.
The parabolic evolutions of elastic modulus and hardness of air plasma sprayed thermal barrier coatings under thermal cycles were studied by nanoindentation method.The experimental data were analyzed by Weibull statistical method to minimize the measurement scatter.The results indicated that elastic modulus and hardness in the interface region of the coating display anisotropic distribution.They increase with thermal cycling and then gradually keep a constant after some thermal cycles.The values of elastic modulus and hardness in the cross-sectional coating are larger than that in the coating surface region.The reason was discussed with the aid of the scanning electronic microscope observations.
JIANG Zhao-hui, FU Peng, JIN Jian, XIAO Chang-fa, LI Xin, KONG Ling-xi. Quantitative Characterization Dispersion of Carbon Black Particles in Polymeric Matrix Based on TEM Images[J]. Journal of Materials Engineering, 2011, 0(10): 72-77.
PP/CB films were prepared with the method of melt blending-masterbatch dilution method,assisted by high-efficiency dynamic mixer.Based on TEM images,the dispersion and distribution of CB particles were characterized quantitatively and qualitatively.The image analysis software,Image J,was introduced to achieve particle number,particle area density,particle size and their distribution.It turns out that the mean diameter of particles is about 0.2μm and equivalent diameter subjects to non-normal multi-peak distribution.The result from origin fitting confirms that area distribution of particles approximately follows lognormal distribution.Quantitative and qualitative characterization were conducted combining TEM images with Morisita’s index(I),Skewness(β) and Lacey index(M) which were used to depict mixing effect.Morisita’s index is 0.985,which demonstrates a uniform distribution of CB particles.The value of Skewness(0.0014) informs us that CB particles in polymer matrix are provided with good dispersion and uniform distribution.Lacey index equals 0.987,which indicates that CB particles and polymer matrix are mixed well.
LIU De-lin, HU Xiao-chun, HE Yu-huai, ZHANG Bing, LIU Chang-kui, JIANG Tao. Hydrogen Brittleness Fracture of Steel Fasteners[J]. Journal of Materials Engineering, 2011, 0(10): 78-83.
The major influencing factors of the sensitivity of steel fasteners to hydrogen brittleness were discussed,and some suggestions were offered as follows.In design,the sensitivity of material strength to hydrogen brittleness should be taken into consideration and lower strength materials should be adopted.Proper heat treatment should be adopted to reduce the distribution of grain-boundary weakening elements along the grain boundaries,change the shape of carbides along the grain boundaries,and restrain the forming of thin-film carbides.During processing and assembly,surface mechanical damage of parts should be avoided.Electric plating processes with less hydrogen brittleness possibility should be used.And some coating technologies with no hydrogen brittleness such as dacromet should be adopted.After electric plating,appropriate dehydrogenation processes should be used.As for repetitive-use parts,the following process procedure should be adopted: pickling(deplating)→dehydrogenation→electric plating→dehydrogenation.
ABULIZI Dilimulati, DUAN Yu-gang, LI Di-chen, LU Zhong-liang. Overview of In-situ Curing Manufacturing Technology for Resin Matrix Composites[J]. Journal of Materials Engineering, 2011, 0(10): 84-90,96.
With the enlargement of application area and increasing use of resin matrix composites,developing automated and low cost manufacturing methods has become a research focus in the advanced manufacturing field.In this paper,the concept,emergence and meaning of resin matrix composites in-situ curing manufacturing technology has been introduced in detail.Researches about various in-situ curing manufacturing methods for resin matrix composites at home and abroad are mainly reviewed,and main advantages and disadvantages of γ-ray,X-ray,heat,microwave,ultraviolet and electron beam curing methods for in-situ curing manufacturing are comparatively analyzed.
JIANG Hai-yun, HANG Zu-sheng, WANG Ji-gang, WU Shen-qing. Thermal Modifying Methods and Progress of Phenol-formaldehyde Resin[J]. Journal of Materials Engineering, 2011, 0(10): 91-96.
Phenol-formaldehyde resin(PF) is one of traditional synthetic polymer materials,which has been widely used in many fields.How to improve its heat resistance is always a hot spot.Thermal modifying methods as well as their modifying efficiency are introduced.At the same time,a proposal is put forward to developing a modifying combination.The combination can not only improve the stability of the structure and properties of PF at 400-700℃,but also stabilizes the one at low,middle and high temperature with a optimized heat-treated process.
