HUANG Jian-cheng, WANG Xin-wei. Crashworthiness Analysis of Composite Structures Based on Elastic-perfectly Plastic Model[J]. Journal of Materials Engineering, 2013, 0(2): 1-6.
Taking composite circular tubes with an external-bevel trigger as an example, an analysis method for the design of crashworthy structures based on elastic-perfectly plastic model is proposed, and the tactics for the determination of equivalent parameters is provided. It is found that composite circular tubes could be equivalent as an isotropic circular tube for crashworthiness design analysis using equivalent elastic constants obtained in terms of macroscopic mechanics of composite materials and critical buckling stresses calculated by finite element codes. It is also found that this numerical modelling strategy requires less computation burden to predict the crashworthiness of composite tubes, and makes it possible to perform the crashworthiness design analysis of full-scale composite aircraft structures with an ordinary personal computer.
YUE Chong-xiang, BAI Xiao-hong, LIU Dong-sheng. F550 High Strength Plate Steel for Shipbuilding Produced by TMCP[J]. Journal of Materials Engineering, 2013, 0(2): 7-11,28.
Continuous cooling transformation (CCT) behavior of a low carbon micro-alloyed SiMnCrNiMo heavy plate steel was investigated employing a Gleeble 3800 thermo-mechanical simulator. A series of thermo-mechanical control process (TMCP) operations were conducted employing a two high reversing pilot rolling mill with accelerated cooling system. F550 shipbuilding plates with yield strength (YS) greater than 590MPa and average Charpy V Notch (CVN) energy at -60℃ higher than 230J were successfully developed by the TMCP. Finish rolling at 800-820℃ with reduction rate 67% followed by accelerated cooling interrupted at 350-500℃ is essential to achieve fine bainite microstructure and superior properties in the F550 plates.
HU Xiao-hua, ZHANG An-feng, LI Di-chen, LU Zhong-liang, HE Bin, GE Jiang-bo. Effects of Heat Treatment on Microstructure and Micro-hardness of Laser Metal Forming DZ125L Superalloy[J]. Journal of Materials Engineering, 2013, 0(2): 12-16.
The microstructure of laser metal forming DZ125L superalloy was studied first. The non-equilibrium microstructure is dense, the primary spacing of dendrites is about 5μm; the generated supersaturated solid solution inhibits γ' phase precipitation and punctuated MC carbides precipitates at the grain boundaries. Unless the necessary heat treatment, it couldn't be used directly. Studies of microstructure and micro-hardness on five kinds condition of heat treatment were carried out. The results show that the homogenization and solution treatment is necessary, but the time must be strictly control; the aging time can be reduced properly. The micro-hardness of the sample which fabricated with heat treatment is the lower than that with as deposit,as the microstructure is dense and strengthening phase MC carbide precipitates at grain boundary.
QI Ya-e, ZHANG Yong-sheng, HU Li-tian. Preparation and Properties Optimization of Al2O3/Al2O3-ZrO2 Laminated Nanocomposites[J]. Journal of Materials Engineering, 2013, 0(2): 17-21.
The Al2O3/Al2O3-ZrO2(3Y) laminated composites were prepared with different starting powders to optimize the preparation process and mechanical properties. The influence of phase structure and morphology of powders on microstructure and properties of laminated composites were investigated via X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and material test system (DY-35). The results show that the particle size and the size distribution of starting powders significantly affect the microstructure and mechanical properties of the laminated composites. The laminated composites with the best mechanical properties and microstructure, which use the micro/nano-sized powders as starting powders, the bending strength and work of fracture are about 740MPa and 3892J·-2,respectively. In addition, the bending strength in the parallel direction of 436MPa can be achieved, which indicate that the composites with better bonding strength.
YAN Shi, LI Dong-hua, PAN Shi-dong, FENG Ji-cai. Analysis of Compressive Fracture Process in 3D Braided Composites by Acoustic Emission[J]. Journal of Materials Engineering, 2013, 0(2): 22-28.
The fracture process of 3D four-directional carbon/epoxy braided composites with different braiding angles under the monotonic compressive loading were investigated by the acoustic emission (AE) technique. The cumulative AE energy, event rate, amplitude, and the peak frequency of a dominant frequency band after treated with the fast Fourier transform (FFT) were analyzed. At the same time, combining with the load-displacement curve varying feature, the fracture processes were divided into different stages to deeply understand the damaged mechanisms of the textile composites. Furthermore, the fracture surfaces of the specimens were observed under optical microscopy. Results reveal that the behavior of AE parameters described well the fracture process in the 3D braided composites with different braiding angles, and the damage mechanisms of the composites can be successfully identified by AE characteristics.
HAO Gang-ling, HAN Fu-sheng, WANG Wei-guo. The Quasi-static Compressive Behavior and Energy Absorption Properties of Mg-based Porous Materials[J]. Journal of Materials Engineering, 2013, 0(2): 29-34.
Porous Mg and porous AZ91D alloy were prepared using powder metallurgy method basing on space holding fillers. The porosity and pore size can be controlled in the range of 40%-80% and 0.5-2.0mm respectively. The investigation was carried out on the quasi-static compressive behavior and energy absorption properties of the Mg-based porous materials. The result shows that the compressive stress-strain curves were consisted of linear elastic region, plateau and densification region. The plateau region is serrated which indicates a brittle deformation mechanism. The dependence of yield strength on relative density can be understood in terms of Gibson-Ashby model, but the effect of pore size is small that can be neglectable. The energy absorption capacity of the Mg-based porous materials increases with the relative density increasing. Porous AZ91D alloy at the same conditions exhibits a higher energy absorption capacity than the porous Mg, that however represents a higher energy absorption efficiency than the porous AZ91D alloy.
FANG Min-jie, REN Hui-lan, NING Jian-guo. The Growth and Evolution of Elliptical Micro-cracks in Quasi-brittle Materials[J]. Journal of Materials Engineering, 2013, 0(2): 35-39.
Growth and evolution of micro-cracks are the mechanism of damage and failure for quasi-brittle materials. The principle for growth and evolution of micro-cracks in quasic-brittle material subjected to loading is studied. The analytical solution is given for the growth of elliptical micro-cracks in elastic deformation stage by the method of complex potential functions. The critical stress condition for the starting damage is derived based on micro-crack growth criterion. The constitutive relation is developed based on the conservation of energy during the wing-crack propagating.
MENG Qing-kun, ZHAO Xin-qing. The Phase Stability of Micrometer Sized Co Particles[J]. Journal of Materials Engineering, 2013, 0(2): 40-44,49.
Two kinds of micrometer sized original particles were annealed in different conditions to prepare Co particles with different crystal structures and different particle sizes. The evolution of the crystal structures and morphologies of particles was analyzed by X-ray diffraction apparatus and scanning electron microscope. It is indicated that almost single FCC phase can be obtained if proper annealing conditions are involved during the annealing of Co particles. There is a critical size of phase stability, below which HCP-FCC transition of Co particles does not occur during cooling and high temperature phase can stably exist at room temperature. The critical size is affected by the state of surface/interface, i.e. lower surface/interface energy gives rise to a smaller critical size. In the view of the suppression of martensitic transformation by extra pressure, the effect of the particle size and the state of surface/interface on the phase stability of Co particles is discussed.
SHI Jian-liang, FU Ye-wei, LI He-jun, FEI Jie, ZHU Wen-ting, ZHANG Xiang. Effects of Carbon Fiber Content on the Performance of New Advanced Ceramic Brake Materials[J]. Journal of Materials Engineering, 2013, 0(2): 45-49.
New advanced ceramic brake friction materials containing five different carbon fiber contents were prepared using molding process. The effects of carbon fiber content on mechanical property, friction performance and wear rate were studied. Worn surfaces of samples were analyzed by Scanning Electron Microscope(SEM). The results show that,with fiber content increasing, both compressive strength and shear strength increase firstly and then decrease, while friction coefficient declines and its stability improves. Materials without thermal degradation at 350℃ show good fading resistance. At lower temperature wear rate tends to increase firstly and then decrease as the fiber content increase. At higher temperature the higher carbon fiber content is helpful to slow the increasing of wear rate.
WANG Zheng, HE Fang-cheng, LIANG Jing, KANG Li-hong. Influence of the Orientation of Laying-up in Composite Laminates on Ultrasonic Inspection[J]. Journal of Materials Engineering, 2013, 0(2): 50-54.
Composite samples used in this study are fabricated by RTM and T700/6421 composite system. The samples were inspected by ultrasonic method. The effect of different laying-up direction on ultrasonic inspection was studied. And the results were given: the orientation of layers influences the velocity and attenuation of the sound wave in composite. So the compensation will be added when defect depth and material attenuation are measured. The orientation of layers of composite laminates doesn't affect the surface resolving power, the ability of finding the defect and the accuracy of estimating defect size.
JIANG Shao-ning, WAN Fa-rong, LI Shun-xing, LONG Yi, LIU Ping-ping, OHNUKI Somei. Evolution of Dislocation Loops in Deuterium-ion Implanted Vanadium Under Electron Irradiation[J]. Journal of Materials Engineering, 2013, 0(2): 55-59.
The evolution of dislocation loops in deuterium-ion implanted pure vanadium under electron irradiation was investigated. Pure vanadium implanted by deuterium ions at room temperature was irradiated by electrons using High Voltage Electron Microscope (HVEM) at 500℃ and 550℃, respectively. Under electron irradiation at 500℃ the dislocation loops remained essentially the same size. The size of dislocation loops formed by aging at 550℃ was a little larger than that formed by aging at 500℃. However, the dislocation loops also showed no change under electron irradiation at 550℃. Vanadium has greater stability of defect clusters under irradiation than iron.
WU Hua, CHEN Tao, SONG Li. Effects of Residual Stress on Quality of (Ti,Al)N Coatings Deposited by PVD Method[J]. Journal of Materials Engineering, 2013, 0(2): 60-64,92.
The (Ti,Al)N coatings were deposited at different bias voltage by ion plating assisted with hollow cathode facility produced in China. X-ray diffraction method was used to study the composition and residual stress of the (Ti,Al)N coatings. There were macro-particles on surface of (Ti,Al)N coatings analyzed by SEM. The adhesion and hardness of (Ti,Al)N coatings were tested by universal nano/micro material tester. The research results show that the residual compressive stress existed in the (Ti,Al)N coatings. Following the augment of bias voltage, the residual stress value decreased first and then increased. The macro-particles on coatings became weaken notably, the adhesion and hardness of (Ti,Al)N coatings increased, the quality and mechanical properties of the coatings were improved when the value of bias voltage enhanced.
LI Yun-gang, TIAN Wei, FANG Xiu-jun. Influence of Preparation Parameter on Microstructure of Cu/Si Gradient Layer Section on Copper Surface[J]. Journal of Materials Engineering, 2013, 0(2): 65-68,98.
Cu/Si gradient layer was made by ihrigizing, on basal body Cu, using the silicon electrodeposited in KCl-NaCl-NaF-SiO2 system as silicon source. The influence of preparation parameter on microstructure of Cu/Si gradient layer section was investigated. The results showed that Cu/Si gradient layer is made of surface layer, intermediate layer and transitional layer with different microstructure, and the microstructure of surface layer and intermediate layer are respectively the equiaxed grain and the columnate crystals organization. The thickness of Cu/Si gradient layer increases with electrodiposition temperature or electrodeposition time, and at the same time,the crystal grain size in surface layers and intermediate layer all decrease. When extending electrodiposition time, the thickness of surface layer gradually increases and the thickness of intermediate layer gradually decreases. In the Cu/Si gradient layer, the phase constitute of surface layer is made of one or two of (Cu), К, γ, η and ε, and the phase constitute of transitional layer is (Cu).
WANG Hong-xing, YANG Shao-feng, LIU Bing-yi, ZHANG Yan. Effect of Packing Temperature on Microstructure and Properties of Siliconized Coating[J]. Journal of Materials Engineering, 2013, 0(2): 69-73.
A layer of electroplating nickel was deposited on copper specimens. Subsequently, these electroplated specimens were siliconized under different packing temperature for a period of 12h by slurry pack cementation process. A slurry pack cementation mixture was composed of SiO2 used as siliconizing source, pure Al powder as reducer, a dual activator of NaF+NH4Cl and albumen (egg white) as cohesive agent. The effect of packing temperature on the microstructure and the mechanical properties of the siliconized coating have been studied. The results showed that the microstructure of the coating is mainly depended upon the packing temperature. As temperature increased during the slurry pack cementation process, the phases of the coating were transformed from Ni31Si12 to Ni31Si12+Ni2Si, and to Ni31Si12+Ni2Si+NiAl, correspondingly, and the process of slurry pack cementation were also changed from the siliconizing-base dual process to the aluminizing-base dual process; the microhardness decreased and the friction coefficient of siliconized coating increased from 0.17 to 0.33 with increasing the packing temperature from 750℃ to 950℃.
QU Jing-long, DU Jin-hui, WANG Min-qing, BI Zhong-nan, ZHANG Ji. Hot Working Technology of Manufacture of GH4720Li Superalloy Fine Grain Bar[J]. Journal of Materials Engineering, 2013, 0(2): 74-77,86.
It is crucial to get uniform and fine grain microstructure for difficult-to-deform GH4720Li superalloy by appropriate hot deforming technology.The law of superalloy cogging and simulation with finite elements and MTS method for GH4720Li superalloy are investigated and the cogging parameters are preliminarily confirmed. On the basis of experimental results, a 406mm diameter ingot was trial-cogged by 2000t quick-forging press. The obtained grain microstructure is uniform and fine. It proves that the cogging parameters obtained by experiments are proper.
LI Wen-xiu, GE Ke-ning, ZHANG Bing, CHEN Li-feng, ZHANG Zhi-gang. Preparation of Hydrophobic Silica Membranes for Methane and Carbon Dioxide Separation[J]. Journal of Materials Engineering, 2013, 0(2): 78-82.
Hydrophobic silica gas separation membranes were prepared by acid catalysed co-hydrolysis and condensation reaction of tetraethylorthosilicate (TEOS) and γ-methacryloxypropyltrimethoxysilane(KH-570) or γ-glycidyltrimethoxysilane(KH-560) or vinyl triethoxysilane in ethanol,characterized by IR,BET,TG-DTG, SEM, the measurement of contact angle,and (0.8KH-570) silica membranes were evaluated by CH4/CO2 gas permeability. The results showed that,as the molar ratio of A-151/TEOS, KH-570/TEOS and KH-560/TEOS increased to 0.8, it was found that the water contact angle were respectively 97.8,94.2°and 90.7°, and the unmodified membrane was only 28.6°.The hydrophobicity of modified membrane samples enhanced. Modified silica membranes had a desirable pore structure,pore size distribution was more narrow and pore width gradually reduced. In the moisture environment, modified silica membranes could be better for resisting water vapor than the unmodified silica membranes.Modified silica membranes were basically free crack, and the surfaces were integrated.Modified silica membrane by KH-570 was best. For the modified silica membranes with KH-570/TEOS molar ratio of 0.8,CH4/CO2 separation factor with the pressure at 30kPa was 2.13, slightly larger than pure silica membrane separation factor (1.58) and the theoretical separation factor(1.67) by Knudsen diffusion.It had a better separation performance.
PAN Yan-ping, WANG Yin, REN Rui, DANG Jiang-min, LIU Chun-ling, DONG Wen-sheng. Synthesis and Characterization of the High Molecular Weight and High-ortho Thermoplastic Phenolic Resin[J]. Journal of Materials Engineering, 2013, 0(2): 83-86.
The high molecular weight and high-ortho thermoplastic phenolic resin was synthesized by using paraformaldehyde and excessive phenol as reactants under normal pressure condition. The influences of various parameters such as the ratio of raw materials, percentage of the catalysts, reaction temperature on the properties of the resultant phenolic resin were investigated. The soften point, the amount of free phenol, gelation time of the resin were measured. In addition, gel permeation chromatography (GPC) analysis, nuclear magnetic resonance spectroscopy (NMR) analysis was also used to characterize the structure of the resin. The high molecular weight and high-ortho thermoplastic phenolic resin with a softening point of 126℃,the weight average molecular weight of 11632,O/P (ortho-/para-) value of 3.49, free phenol mass fraction of 2.76%, gelation time of 12s, flowing distance of 39 cm and a yield of 94% was synthesized successfully.
GUAN Yong-yong, XU Rui-dong, HUANG Li-ping, KONG Ying, CHEN Bu-ming. Preparation and Electrochemical Performance of Al/Pb/α-PbO2 Inert Anodes[J]. Journal of Materials Engineering, 2013, 0(2): 87-92.
Al/Pb/α-PbO2 inert anodes used in zinc electrowinning were prepared on the surface of aluminum alloy substrates by means of single-pulse electrodeposition, the influences of pulse average current densities from 2A·dm-2 to 5A·dm-2 on the electrochemical properties of the composite inert anodes in a synthetic zinc electrowinning electrolyte of 50g·L-1 Zn2+, 150g·L-1 H2SO4 and 35℃, were researched, and the anodic polarization, cyclic voltammetry and Tafel polarization curves were measured. The results show that in [ZnSO4+H2SO4] electrolytes and at the same testing current density, oxygen evolution potential or overpotential of oxygen evolution of composite inert anodes gradually increase with the rise of pulse average current densities from an original plating bath. The inert anode prepared at 2A·dm-2,possessess lower oxygen evolution overpotential,higher corrosion potential and lower corrosion current than those of Pb-1%. Ag alloy anode.
WANG Jiong, LI Min, GU Yi-zhuo, WANG Shao-kai, ZHANG Zuo-guang. Investigation of Co-cured Liquid Composite Molding and Interlaminar Property for Carbon Fiber Composites[J]. Journal of Materials Engineering, 2013, 0(2): 93-98.
The carbon fiber/epoxy resin matrix composite laminates were fabricated using co-cured liquid composite molding (LCM). The compaction of laminates and diffusion of the two kinds of resins were investigated. Mode-I delamination fracture toughness and short beam shear strength were measured to evaluate the interlaminar property of the co-cured laminates and were compared with those of laminates processed by prepreg molding and liquid composite molding. Moreover, the effects of fiber orientation at the interface between prepreg part and LCM part on GⅠC were studied. The results show that the laminates processed by co-cured LCM have high compacting degree in the intralaminar plies and have no obvious resin-rich area between plies. The two kinds of resins at the interface between prepreg part and LCM part diffuse to some extent. Affected by the diffusion of the two kinds of resins at the interface, the interlaminar fracture toughness of co-cured laminate is equivalent to the average of those of the prepreg laminate and LCM laminate, while short beam shear strength is determined by the weaker part. The fiber orientation at the interface between prepreg part and LCM part has significantly influence on GⅠC, and [45/90] fiber orientation has a better resistance to interlaminar fracture and propagation of delamination.
