XIA Qing-kun, LIU Zhi-yi, YU Ri-cheng, LI Yun-tao. Analysis on Microstructure and Residual Intensity of Al-4.72Cu-0.45Mg-0.54Ag-0.17Zr Alloy in High Temperature Lasting[J]. Journal of Materials Engineering, 2006, 0(11): 3-8,12.
The microstructure and performance of Al-Cu-Mg-Ag-Zr Alloy aging in 165℃ have been investigated,and the high temperature lasting test is done in 200℃ and 200MPa employing underageing(165℃×2h)and peakageing(165℃×6h) samples.The results indicate that with the prolonging of lasting time,the residual stress of underageing samples appears to be increase first and then decrease,and the peaking stress is obtained when lasting for 20h.The variation of ductility of the underageing samples has the same tendency with the variation of residual stress.Compared with underageing condition,the mechanical properties have no obvious variation after lasting for 100h,which represents superior heat-resistance ability.The high temperature lasting performances of underageing are superior to that of peakageing.
LIU Wei-hong, SUN Da-qian, QIU Xiao-ming, SUN De-xin. Diffusion Bonding of Aluminium Metal Matrix Composite with Ni Interlayer[J]. Journal of Materials Engineering, 2006, 0(11): 9-12.
The effects of bonding temperature and bonding time on the microstructure and mechanical property of diffusion bonded aluminium-based metal matrix composite Al2O3P/6061Al joint with Ni interlayer have been investigated.The experimental results show that,within the bonding temperature range of 610-620℃,the bonding region mainly consists of Al3Ni and aluminium solid solution,and with increasing the bonding temperature and holding time results in the decrease of the amount of Al3Ni in the joint.At the bonding temperature 630℃,the bonding region mainly consists of alumina particle and aluminium solid solution,in which alumina particles segregate in the center of the joint.For the joint bonded at 620℃/5-120min,shear strength is 68-93MPa and fracture occurs at the bonding region/base metal interface.For the joint bonded at 630℃/5min-120min,shear strength is 93-97MPa and fracture occurs at alumina particle segregation region.
YANG Fu-biao, XIAO Jia-yu, ZENG Jing-cheng, JIANG Da-zhi, WANG Zun, XING Su-li. Anodizing Treatment and Its Effects on Properties of Cracked Aluminum Plates Repaired with Composite Patches[J]. Journal of Materials Engineering, 2006, 0(11): 13-17,21.
The center-cracked aluminum alloys plates were bonded repaired with unidirectional carbon/epoxy composite patches,some of which were anodized in the aqueous solution of phosphoric acid.The adhesive properties of the anodized plates were investigated.The effect of anodizing on the static and fatigue properties of the repaired structure was analyzed.It is shown that the anodizing produces the porous and micro-rough film on the surface of plates.When the anodized plates are bonded with composite patches,the adhesive penetrates into the film and a transition layer is formed between the alloy and the adhesive.The adhesion is promoted greatly and the maximum lap shear strength of the anodized sample is 104% greater than that of the normal samples.The static and fatigue properties of the repaired plates are improved greatly after anodizing treatment.The failure strength of repaired plates is 418.13MPa when the plates are anodized,which is 93.42% of that of the no-flaw plates.The fatigue life of repaired plates is 1.42 times longer than that of cracked plates when the plates are anodized,which is 27.59% longer than that of the normally repaired ones.The residual strength of the repaired plates after a number of fatigue cycles is improved significantly when the cracked plates are anodized before repair.
GU Mei-lin, HUANG Chuan-zhen, LIU Bing-qiang, ZOU Bin, LIU Zeng-wen. Microstructure and Mechanical Properties of Ceramic Tool Materials TiB2-TiN[J]. Journal of Materials Engineering, 2006, 0(11): 18-21.
The ceramic composites TiB2-TiN-(Ni,Mo) with different contents of TiN were fabricated by hot press technology and the mechanical properties were measured. It can be found that the flexural strength and fracture toughness of the composites increase consistently with an increase in the TiN contents.But Vicker’s hardness of the composites deteriorates when the content of TiN reaches 40%(volume fraction).Microstructures of the composites were investigated by XRD,SEM and EDAX analysis.It shows that a new crystalline phase of MoNi appears after sintering.And the fracture pattern is changed from intergranular to transgranular mode when raising the TiN contents.Metal grain crack bridging and crack deflection improve the fracture toughness of the composites.
DENG Qiong, ZENG Qing-xuan, FENG Chang-gen. Study on Preparation and Properties of Polyvinyl Alcohol Based Alkali Anion Exchange Fiber[J]. Journal of Materials Engineering, 2006, 0(11): 22-26.
The strong alkali anion exchange fiber were prepared by the dehydration reaction of polyvinyl alcohol(PVA) fiber followed by etherisation reaction and amination reaction.The paper studied the effects of dehydration atmosphere,temperature and time on dehydration reaction and the effects of mass loss,temperature,time of etherisation and amination reaction on exchange capacities.IR,XRD and determinations of titration curve,absorption dynamics,and mechanical strength have been used to characterize the structure and appearance of PVA anion exchange fiber.The results show that nitrogen atmosphere can effective protect the mechanical property of fiber.When the mass loss rate of dehydration reaction was 10%-15%,the exchange capacity of strong alkali anion exchange fiber was 1.9-2.4 mmol·g-1 and the fiber had a high exchange capacity,quick adsorption velocity and finer mechanical capability.
LIU Min, ZHU Hai-kui, ZHOU Hong-qing. Effects of Additives on La2Ti2O7 Ceramic Properties[J]. Journal of Materials Engineering, 2006, 0(11): 27-29,35.
The influence of the additives such as ZnO,Nb2O5 and H3BO3 on sintering and dielectric properties of La2Ti2O7 ceramic was investigated,and the mechanism also discussed.The results showed that La2Ti4O7 ceramic with proper additives can be sintered between 1220℃ and 1300℃.The dielectric constant of La2Ti2O7 ceramic with 1%ZnO,0.5%Nb2O5 and 3% H3BO3 was 48 and 40 respectively,the dielectric loss was about 10-4.The temperature coefficient of dielectric constant at 10kHz was about-24×10-6/℃ and-48×10-6/℃ respectively.The material has good dielectric properties,which can be used as dielectric material.
ZHANG Guang-ye, GUO Jian-ting, ZHANG Hua, WANG Zhen-sheng, YIN Yan-zi. Investigation of Microstructure and Mechanical Properties of DS NiAl/Cr(Mo,Hf) Alloy[J]. Journal of Materials Engineering, 2006, 0(11): 30-35.
The microstructure and mechanical properties of NiAl-28Cr-5.5Mo-0.15Hf alloy have been investigated at the temperature range of 293-1373K.The results showed that the heat treatment DS NiAl-28Cr-5.5Mo-0.15Hf alloy was composed of three phases,which were a lamellar Cr(Mo) phases,NiAl matrix and a semicontinuous distributed Ni2Al Hf phase with little amount.The other Hf element existed via solution.It was also observed that the brittle-to-ductile transition for this multiphase alloy was sensitive to strain rate.At the room temperature, the fracture was characterized by predominantly debonding.Beyond the BDTT,the fracture of tested specimens with larger elongation was characterized by large amount of void at the fracture surface.
WANG Jian-min, ZHU Xi, LIU Run-quan. Micro-analysis of Bonding Interfaces of Explosive Welded Aluminum/Steel Plates[J]. Journal of Materials Engineering, 2006, 0(11): 36-39,44.
The bonding interfaces of explosive welded aluminum-steel plates were analyzed by means of metallographic microscope and electron probe micro-analyzer(EPMA).The results indicated that the bonding interfaces of aluminum-steel was of straight shape and brittle layers were produced at the interfaces and in which some micro-cracking were observed.During explosive welding,a thin metal layer near the interfaces was melted with the explosive energy and plastic deformation was found on the grains at the interfaces.A 5μm diffusion distance was found on the both sides of base metals at the direct bonding interfaces.It was analyzed that the characteristics of explosive welding technology and physical characteristics of aluminum and steel decided the micro-structure of the aluminum-steel bonding interfaces.Furthermore,the effects on the bonding strength of aluminumsteel were discussed.
DENG Cheng, SONG Yong-cai. Preparation and Electromagnetic Properties of Nickel Fibers by Citrate Sol-gel Method[J]. Journal of Materials Engineering, 2006, 0(11): 40-44.
The nickel fibers had been successfully prepared with citric acid and nickel carbonate basic as the starting reagents by sol-gel method.This process included preparation of sol precursor with good spinnability,dry spinning and pyrolysis. The diameter of the fibers obtained was about 10-20μm.In this article,different raw materials and additive agent were studied to improve the spinnability of sol precursor,and phase of fibers was also investigated in different decomposition atmosphere.The complex permittivity ε and complex permeability μ of nickel fibers are decreased with increasing of the experimental frequency in 2-18GHz band,which represents good dispersion characteristics.
FANG Zhen-qian, HU Ming, DOU Yan-wei, ZONG Yang, LIANG Ji-ran. Study of Porous Silicon Prepared by Galvanic Corrosion Method[J]. Journal of Materials Engineering, 2006, 0(11): 45-48,52.
Porous silicon was prepared by using the galvanic corrosion method.The optimal process of Pt electrode and the effects of etching conditions on the thickness of porous silicon were studied.The surface morphologies of porous silicon were investigated in terms of scanning electron microscope(SEM) and atom force microscope(AFM).The results showed that the thickness of the porous silicon layer will augment with the accretion of the thickness of Pt electrode and the area ratio of Pt electrode to etching silicon substrate in the same etching conditions.
ZHANG Dong-mei, HAN Jie-cai, ZHANG Bo-ming, MENG Song-he. Research on Ablation Property of Carbon-based Composites[J]. Journal of Materials Engineering, 2006, 0(11): 49-52.
The ablation property of carbon-based composites during the reentry was simulated by the ground-simulating system,which is based on the AC star type arc heater.The ablation procedure was real-time monitored by the manner of temperature measurement on material surface,image acquisition and emission spectrum.All of these have offered necessary theoretic basis for ablation mechanism of carbon-based composites,and characterization of service performance and material optimum design.
ZHOU Xiao-ming, WANG Wu-xiang, TANG Ding-zhong, YAN Ming-gao. Genetic Characteristic of SiO2 in FGH96 Superalloy[J]. Journal of Materials Engineering, 2006, 0(11): 53-56,61.
The different processing characteristic of SiO2 particles in FGH96 superalloy was investigated.The results showed that the edge of SiO2 particle tends to be smooth,and there was a reaction zone at the interface between SiO2 particle and the matrix,which made SiO2 particle become a "compound" non-metallic inclusion.The driving power used for the reaction was surface energy of powders and SiO2 particles strain energy generated during HIP in powders.In the following processes,SiO2 particles showed slight difference in characteristic of morphology,size and distribution of elements.
GUO Shi-bo, QU Xuan-hui, DUAN Bo-hua, HE Xin-bo, QIN Ming-li. Study on Powder Properties of Titanium Alloy by Powder Injection Molding[J]. Journal of Materials Engineering, 2006, 0(11): 57-61.
Influence of powder properties such as particle size distribution,particle shape,special area ratio on PIM processing was investigated systemically.Powder characteristics affecting feedstock properties and PIM processing were picked out and their empirical models were established.The relationship between powder characteristics(Dv,Sw,Ar,σ)and powder packing density(ft) was formulized as ft=235.0+0.20Dv+32.18σ-29.17Sw-26.81Ar.Powder characteristics affected the fluidity of the powder(Mi) according to the equation Mi=240.38-33.54Sw-32.08Ar.Powder characteristics affected injection molding parameters such as injection temperature(Ti),injection pressure(Pp),injection holding time(th) according to the equation Ti=12.35+1.86-16.0Sw+145.5Ar,Pp=-289.63-18.35Sw+256.28Ar,th=-2.36+5.63Ar+0.10Dv0.95Sw.
YU Mei-jie, WANG Cheng-guo, ZHU Bo, XU Yong. Review on the Thermal Stabilization of PAN-Based Carbon Fiber Precursors[J]. Journal of Materials Engineering, 2006, 0(11): 62-66.
The research progress of thermal stabilization of polyacrylonitrile-based carbon fiber precursors was reviewed.The mechanism of stabilization reactions,the microstructure of stabilized fibers and the effect of processing parameters were discussed in detail.The study prospective of thermal stabilization was proposed.
