XU Hua-ming, WANG Rui, GUO Li-qiu, LIANG Ji. Discrete Growth of Single-walled Carbon Nanotubes on Surfaces[J]. Journal of Materials Engineering, 2007, 0(3): 3-6.
Catalyst particles were obtained by spin-coating isopropyl alcohol solution of Fe(NO3)3 on surface of P-type silicon.These particles can catalyze the decomposition of CH4 and growth of single-walled carbon nanotubes(SWNTs).On surface of P-type silicon,the distribution of SWNTs is uniform and some of SWNTs are erect.The influences of concentration of catalyst,substrates,reaction temperatures were investigated.Increase in catalyst concentration or silicon dioxide replacing P-type silicon as substrate could lead to denser SWNTs,shorter SWNTs and decrease in erect SWNTs on surface.With higher reaction temperature,growth of SWNTs is with lower efficiency and with higher probability to be affixed on surface of substrate.By pick-up method,carbon nanotube Atomic Force Microscopy(AFM) tips were successfully fabricated by imaging the nanotubes-covered substrates in tapping mode of AFM.
ZENG Guo-xun, ZHANG Hai-yan, HU Li-chu, CHEN Yi-ming. Effect of Al2O3 Concentration upon Complex Permittivity of Fe/Al2O3 Composites[J]. Journal of Materials Engineering, 2007, 0(3): 7-9.
The sheets of ferrite composites with different concentration of Al2O3 were synthesized by citric nitrate sol gel method.The mixture powders have the fine and nano Fe/Al2O3 composites were obtained,in which the ferrite was reduced by hydrogen.It is found that Fe/Al2O3 composites have a shape of needle and flake by SEM examination.The real and imaginary parts of the complex permittivity of Fe/Al2O3 composites decreased,and dielectric loss(ε″) peak shifted to higher frequency with the increase of Al2O3 concentration in Fe/Al2O3 composites.Relative permittivity of Fe powders is adjusted by adding different Al2O3 concentration.
XU Ya-dong, QIAN Lin-fang, SHI Xiu-dong. Damping Analysis of Fiber Reinforced Composite Material Barrel[J]. Journal of Materials Engineering, 2007, 0(3): 10-13.
Aiming at the damping effect of the fiber reinforced composite material barrel during gun firing,the energy dissipation formula of fiber reinforced composite material is given based on the dynamic characteristic principle of viscoelastic material.By using modal strain energy finite element analysis method,the damping analysis for some caliber composite material barrel is conducted.And the strain energy and modal loss factors are obtained for each mode of composite material barrel,which provide the damping parameters for the dynamic analysis of the barrel.
LI Xiao-li, JIA Hu-sheng. Microwave Absorbing Properties of Carbonyl Iron Fiber[J]. Journal of Materials Engineering, 2007, 0(3): 14-17.
The carbonyl iron fibers were prepared by the magnetically-induced mental organic chemical vapor decomposition(MOCVD).The electromagnetic parameters of the carbonyl iron fibers of different mass fraction and different thickness with same mass fraction were measured and analysised.It was found that low mass fraction and thinner thickness could get good microwave absorbing properties.
REN Hui-lan, NING Jian-guo. Micro-cracks Damage Constitutive Model of Quasi-brittle Materials Subjected to Shock Compression[J]. Journal of Materials Engineering, 2007, 0(3): 18-21.
Based on the nucleation criterion of wing tension crack of quasi-brittle material,the decrease of elastic moduli of material resulted from the crack damage are derived utilizing micro-mechanics theory.The influence of crack growth velocity on dynamic failure toughness is considered in dynamic growth criterion.The damage constitutive model for brittle materials subjected to compressive loading is developed.The influence of parameters of micro-cracks nucleation,initial crack size on dynamic failure strength are discussed.The stress-strain curves under high strain rate for alumina are compared to the experimental results and a good correlation is obtained.
JIN Hai-peng, LI Jia-rong. Tensile Properties of Second Generation Single Crystal Superalloy DD6 After Long Term Aging at High Temperature[J]. Journal of Materials Engineering, 2007, 0(3): 22-23,52.
The investigations of tensile properties of the second generation single crystal superalloy DD6 after long term aging at elevated temperature were presented.The results indicate that DD6 alloy with orientation has excellent tensile properties at 760℃ after longterm aging at 980℃.Tensile strength exceeds 1000MPa and yield strength is near 900MPa after aging for 1000 hours.The effects of grown γ' phases on tensile properties of DD6 at 760℃ are not obvious.
ZHANG Jian, ZHENG Hai-zhong, XU Zhi-feng, SUN Sheng-wei, LIU Yue-hua. Study on Characterization of Core-shell Nano-Al2O3/PS Composite Particles and Toughening Polystyrene Prepared by SLS[J]. Journal of Materials Engineering, 2007, 0(3): 24-27.
Surface of nano-Al2O3 particle was covered with PS by emulsion polymerization to prevent the reunion.The structure of emulsion polymeric Al2O3/PS composite particle was characterized by TEM and FTIR.The results indicate that the composite particles are approximate ball shape and the particle consists of centered core(Al2O3) and outer shell(PS).The composite particles were used as fillers to toughen PS based composites prepared by selective laser sintering(SLS).It was founded the notched impact strength of treated composites increased 50% than that of unfilled PS and increased 30% than that of untreated composites,the maximum value was 12.1kJ/m2;FE-SEM studied the tensile fracture surfaces of the sintered specimens.It was noted the fracture surfaces of composites with treated nanoparticles were rougher than those of unfilled PS and those of the untreated composite,and the interfacial compatibility and adhesion property are improved,which toughened PS prepared by SLS well.
FANG Xiao-Yong, CAO Mao-Sheng, HOU Zhi-Ling, ZHANG Yong, LI Zhong-ping. Research of Dielectric Properties for Silicon Dioxide Composite at High Temperature[J]. Journal of Materials Engineering, 2007, 0(3): 28-30,41.
Based on the analysis of the influence factors on the dielectric properties of silicon dioxide composite at 25-1200℃,experiential model is established through the effective medium theory,which can describe the dielectric properties of silicon dioxide composite at high temperature.Moreover,the comparison between the calculation and experimental results shows that the model is creditable and reasonable.Dielectric properties are predicted for silicon dioxide composite at 1200-1500℃.
HUANG Li-jun, HUANG Xu, CAO Chun-xiao. Nanoindentation Characteristics of Ti-12Mo-6Zr-2Fe Titanium Alloy[J]. Journal of Materials Engineering, 2007, 0(3): 31-33,37.
The hardness and elastic modulus of Ti-12Mo-6Zr-2Fe titanium alloy have been inspected by means of nanoindentation.It showed that the hardness of Ti-12Mo6Zr-2Fe is higher than that of Ti-6Al-4V ELI,while the elastic modulus of Ti-12Mo-6Zr-2Fe is lower than the that of Ti-6Al-4V ELI,this results consist with the rule obtain by conventional testing method.The nanoindentation method can describe the mechanical properties of titanium alloys,but its results could not transfer to conventional tested results,and the surface status of the specimen has some kind of effect on the testing results.It is highly advantageous to evaluating the mechanical properties of titanium alloys by means of nanoindentation method.
SONG Pei-wei, GUO Xue-feng, JING Xiao-tian, ZHANG Zhong-ming, XU Chun-jie. Spheroidization of Mg2Si Particles in Mg-4Al-2Si Alloys During Solution Treatment Process[J]. Journal of Materials Engineering, 2007, 0(3): 34-37.
The spheroidization of the coarse ‘Chinese script’ Mg2Si in Mg-4Al-2Si alloys and technical parameter role to the spheroidization are studied.The results show that the Mg2Si particles is dissolved partially and tend to be spheroidized during the treatment due to the diffusion of Si atoms along the Mg/Mg2Si interface.The optimum technics are 420℃,16h.
LI Guo-dong, LI Zhuo-xin, WEI Qi, WANG Ying-jie. Study on the Physical Characteristic of Argon-helium Arc and Its Effects on the Weld Shaping[J]. Journal of Materials Engineering, 2007, 0(3): 38-41.
The arc physical characteristic of mixed gases(Ar+He+CO2) and its effects on weld shaping were discussed.The results show that columnar center zone was observed in the tri-mixed gas arc shape.When the helium content is less than 45%,the character of tri-mixed gas has no evident difference compared with that of argon.When the helium content in the tri-mixed gas excesses 75%,the arc presents the characteristic of helium.With the increasing of helium content in the mixed gases,the arc voltage increase,and the weld width broaden,especially the weld penetration deepens obviously.
LIU Peng-fei, SHAN Ping, WANG Xiao-feng, HU Sheng-sun. Effect of Deep Cryogenic Treatment on Wear Resistance of Cr-Zr-Cu Alloy for Electrode of Spot Welding[J]. Journal of Materials Engineering, 2007, 0(3): 42-45.
For discovering the effect of deep cryogenic process to wear resistance of Cr-Zr-Cu alloy,the change of wear resistance of Cr-Zr-Cu alloy to time and temperature of deep cryogenic were investigated through changing the time and temperature of deep cryogenic,the result showed that effect of the two parameters was obvious.The wear resistance of this alloy ascent to a peak value,when temperature fall to-150℃.When warming timeis larger than 2h,the wear resistance of this alloy become approximately invariability.
HONG Run-zhou, ZHOU Yong-jiang, YAO Wei-bin, XIONG Yan-cai. Study on Rotary Impeller Degassing of ZL114A Alloy[J]. Journal of Materials Engineering, 2007, 0(3): 46-48.
Rotary impeller degassing has been used to refine ZL114A alloy,The parameters of the refining equipment has been settled with comparing effect of different impeller rotation speed and flux of Ar2,the rule of content of H2 with refining time has been studied,and the best process parameters of rotary impeller degassing has been carried out.The content of Mg before and after refinement has been compared and the mechanical properties of ZL114A after refiment has been tested,the results indicate that the reduction of content of Mg is very low,the mechanical properties of ZL114A after refiment is high.
XIE You-hua, LU Zheng, DAI Sheng-long. Mechanical Behavior of Al-6Mg-0.2Sc Aluminum Alloys at Elevated Temperature[J]. Journal of Materials Engineering, 2007, 0(3): 49-52.
Mechanical property of Al-Mg-Sc superplastic alloys at 200-500℃ was investigated,and microstructure of remaining specimen was examined.The result indicated that during 200-500℃ Al-Mg-Sc alloys showed certain superplasticity.Superplastic forming at 300-400℃ which sheets exhibited lower strength was feasible under engineering condition,and the workpiece obtained better performance.At about 300℃,below which the strength of grain boundary is higher than the strength of grain,above which the strength of grain is higher than the strength of grain boundary,fracture mechanism transited from ductile fracture to brittle fracture.
GUAN Ying-chun, TANG Guo-yi, YE Qiang. Investigation of Defects on Mirror Plastic Mould Surface[J]. Journal of Materials Engineering, 2007, 0(3): 53-57.
The macroscopic protuberance defects on the surface of 1.2083 mirror plastic mould,which was formed during the polishing process,were analyzed.The morphology,structure and composition of the defects and the relationship with nonmetal inclusions were observed by Optical Microscopy and Scanning Field Emission Microscopy.Furthermore,the surface roughness of the failure mould product and the metallographic specimens were measured and contrasted.The results show that the protuberance defects on the surface of the failure mould product were caused by kinds of nonmetal inclusions and inhomogeneous chemical composition in some area of this mould steel,which destroyed the matrix continuity during the polishing process.
WANG Cai-mei, ZHOU Xue-yu, SUN Yuan, HE Kao-tuan. Application of Aviation Materials in Implants for Surgery—Joint Prosthesis[J]. Journal of Materials Engineering, 2007, 0(3): 58-61,66.
In the developing course of modern material science &technology,aviation materials always play the pilot and basic role.The aviation materials,such as superalloys(mainly cobalt-base alloys),titanium-base alloys,stainless steels,ceramics,highly abrasionproof nonmetals,have become excellent clinical materials because of their premium properties of light mass,high strength,fatigue resistance,heat resisting,high reliability and biocompatibility,have been widely applied in surgical implants.The rapid developing of artificial joints both,depends largely on the application of aviation materials.This article aims to present the properties and the application requirements of the aviation materials which are presently used in surgical implants.
MA Yan, MA Qing-song, CHEN Zhao-hui. Present State of Porous Ceramics by Preceramic Polymer Pyrolysis[J]. Journal of Materials Engineering, 2007, 0(3): 62-66.
Porous ceramics is widely used in various fields because of its excellent performance,and its fabrication methods have been developing all the time.The preceramic polymer pyrolysis appearing in late 20th century is a new route to fabricate porous ceramics,and it has attracted increasing attention in recent years because of its many advantages,such as low sintering temperature,flexible processing route,high fracture strength,and so on.According to the configuration of porous ceramics,there are two kinds of means to make porous ceramics by preceramic polymer pyrolysis,namely bulk structure porous ceramics and ceramic foams.This article introduces the processing,structure and properties of the two kinds of porous ceramics by preceramic polymer pyrolysis,including existing problems needed to resolve.
