ZHANG Lin-jin, YE Xu-chu, LU Xiu-wei. Experimental Study on Preparation of Silicon Nitride by High-temperature Fluidization[J]. Journal of Materials Engineering, 2009, 0(11): 1-3.
Silicon nitride was synthesized by high-temperature fluidization using self-designed fluidized bed.The effect of temperature for silicon fluidization was studied.The conversion with different reaction time was obtained by K value method.The result indicated that the minimal velocity of fluidization ascended with increased temperature.The induction period existed in the initial stage.The reaction was rapid with the conversion rate between 20% and 40%.Then,the reaction rate decreased and keep invariable after 160min.The utilization of fluidization provided experiment foundation for the consecutive preparation of silicon nitride.
SHANG Jian, ZHANG Yong-zhen, QIU Ming, XU Yong-zhi. Effect on Friction and Wear Behaviour of 45 Steel in Direct Current Constant Magnetic Field[J]. Journal of Materials Engineering, 2009, 0(11): 4-7,13.
The influence of D C constant magnetic field on tribological behaviour of 45 steel pin against disc in atmosphere was investigated.The results indicated that the wear loss decreased and friction coefficient went down,the worn surfaces were smooth and debris were fine obviously with a magnetic field.Microscopic analysis by SEM and EDS showed that more oxide-protective film formed on worn surface in the presence of a magnetic field.Oxidative wear mechanism and lubricated effect of debris were stated,which played an important role during the friction and wear.
FU Shu-hong, DONG Jian-xin, ZHANG Mai-cang, XIE Xi-shan. Thermodynamic Calculation of the Phases Precipitation Behavior for Developing 718 Type Alloys with High Structure Stability[J]. Journal of Materials Engineering, 2009, 0(11): 8-13.
The effect of the alloying elements C,Al,Ti,Nb and W in 718 type alloys on equilibrium phases precipitation behavior was investigated employing the Thermo-Calc software and nickel-base superalloy database.Chemical composition of the equilibrium phases was also calculated.The calculation results provide the theoretical bases for developing 718 type alloys with high structure stability.
GENG Yu, SONG Yan, TIAN Yong-ming, GUO Quan-gui, LIU Lang. Influence of Activated Condition on the Pore Structure of Phenolic Resin Based Activated Carbon Cloth and the Electrochemical Performance of Supercapacitors[J]. Journal of Materials Engineering, 2009, 0(11): 14-19.
Phenolic resin based activated carbon cloths(ACCs) were prepared by steam 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 N2 adsorption,AC impedance and constant current discharge techniques.The relationship of pore structure and the activated conditions,as well as the relationship between the pore structure and electrochemical performance in 1M(CH2CH3)3CH3NBF4/PC were discussed in details.Results showed that the BET surface area,average pore width and mesoporous surface area dramatically increased with the increase of activation temperature and/or activation time.It was also found that the specific capacitance of ACCs increased with the increase of BET surface area,especially the specific capacitance of the sample activated under 950℃ for 90min reached 158F·g-1 at current density of 50mA·g-1.Besides,the capacitance retention of ACCs at high current density increased with the increase of mesoporous surface area,of which the capacitance retention(C500/C50) of the sample with the largest mesoporous specific surface area reached 91.1%.IR drop reduced sharply in the pores less than 2nm with the increase of average pore width.
ZHOU Zhen-ze, ZHANG De, XU Jian-mei, DONG Jin-wen, GAO Hui-juan, JIANG Shen-lin. Investigation of Synthesizing Processes of Ba3(VO4)2[J]. Journal of Materials Engineering, 2009, 0(11): 20-22,91.
Ba3(VO4)2 is a kind of promising microwave dielectric ceramics system which can co-fire under low temperature together with silver or copper electrode.Ba3(VO4)2 powders were synthesized with BaCO3,V2O5 raw materials under different temperatures.The crystal structure and reaction process of the samples synthesized under different temperature were analyzed by X-ray diffraction.It showed that BaCO3 and V2O5 had begun to react without V2O5 peaks in XRD figures of powders when only treated by ball milling and drying.The intermediate products in the synthesizing processes of Ba3(VO4)2 are as follows: Ba(VO3)2·HO2,BaV2O6,Ba2V2O7,Ba3(VO4)2.Ba3(VO4)2 crystal phase began to be synthesized at 450℃ and the pure phase Ba3(VO4)2 can be obtained at 800℃ by XRD results.
SONG Ying-gang, CROSS M. D. J. , RAINFORTH W. M., WYNNE B. P.. Effect of Interpass Time on Crystallographic Texture During Rolling Processing of AA6111 Aluminum Alloy[J]. Journal of Materials Engineering, 2009, 0(11): 23-26.
The effect of interpass time during rolling processing of AA6111 aluminum alloy on the evolution of crystallographic texture had been investigated by electron back-scatter diffraction(EBSD) techniques.The results revealed that the texture was mainly composed of the α and β fibres.From the orientation density of the major texture components,with an increase in delayed time,Brass and Copper ideal texture components became predominate,S texture had no difference.
CAO Guo-liang, LI Guo-min, CHANG Wan-shun, CHEN Shan, CHEN Xue-qun. Influence of Deoxidization on Resistance Against Pitting Corrosion of Carbon Steel[J]. Journal of Materials Engineering, 2009, 0(11): 27-30,35.
Four carbon steels with different deoxidization degrees had been selected.Pitting susceptibility of steel was compared by means of polarization tests in 3%NaCl with pH=10.The ability to propagate of pits was evaluated by occluded corrosion cell and hanging plates.The results showed the main inclusions in steel A and steel B were olivelike sulphide and MnO,while the typical inclusions in steel C and steel D were the strip-like silicate and sulphide inclusions,respectively.Under the same condition,the killed steels exhibited weaker pitting susceptibility and the lower rate of pit propagation than rimmed steels do.Too low content of P in the killed steels helped to the accelerate propagation of pits.
CHEN Lie, XIONG Jun-jiang, CHENG Ze-lin. Experimental Investigation on Shear Strength of Composite Single-lap Joints[J]. Journal of Materials Engineering, 2009, 0(11): 31-35.
Shear experiments of three types of single-lap composite joints,processed respectively by using RTM,stitched RTM and adhesively bonded techniques,are carried out to investigate the influences of process on mechanical properties of composite single-lap joint and failure mechanism is discussed from experimental observation.It is shown from experimental results that the composite single-lap joints,processed by stitched RTM and adhesively bonded techniques,respectively,have the greatest and least shear strengths in three types of joint.And there is a slight influence of hygrothermal and high temperature environment on shear strength of composite single-lap joints,processed by means of RTM and stitched RTM techniques,whereas a significant effect on that by using adhesively bonded technique.
ZHENG Wen-jing, ZHOU Wan-cheng, LUO Fa, YU Xin-min. Preparation and Dielectric Properties of Carbon-coated SiC Fibers[J]. Journal of Materials Engineering, 2009, 0(11): 36-39.
A carbon coating of 100nm thick was prepared on the surface of SiC fibers by chemical vapor deposition method.The effect of fabrication temperature on microstructure of carbon coating and on the body conductivity,permittivity of carbon-coated fiber was studied.Scanning electron microscopy and Raman microscopy were employed to investigate the surface morphology and microstructure of the coatings.The results show that when fabrication temperature increases from 800oC to 900 oC,the crystallization degree and the grain size of carbon coatings increase and the body conductivity of SiC filament also increases from 0.745Ω-1·cm-1 to 6.289Ω-1·cm-1.The real part of complex permittivity of SiC woven sheet increases from 90 to 132,imaginary part from 87 to 150,respectively,and the dielectric dissipation fraction increases from 0.95 to1.14 at the same time.The increase of the real part and imaginary part has connection with the increased density of current carrier and missed conductivity,respectively.The changes above are attributed to the conductivity increases of the carbon coatings on SiC fibers.The dissipation derived from direct current conductivity is the primary mechanism of the dissipation above all.
REN Ji-lin, SHU Ming-hang, WU Jia-ju, SONG Kai, CHEN Xi, CHEN Chen. Simulation of Stress-magnetization Effect on 18CrNi4A Steel by ANSYS[J]. Journal of Materials Engineering, 2009, 0(11): 40-44.
To analysis the stress-magnetization effect on 18CrNi4A steel specimen under the geomagnetic field,the mode of the specimen and the air around it was constructed with the help of ANSYS,famous software of Finite Element Analysis(FEA).The stress and magnetic flux leakage distribution of the mode was given.The influences of stress concentration under the geomagnetic field on magnetic memory signal were discussed.Lastly,through the contrast analysis between finite element result and experimental phenomena,the summing-up was given,providing the gist for the deep-going study of magnetic memory testing theory and experiment.
WANG Bin, YI Dan-qing, FANG Xi-ya, LIU Hui-qun, WU Chun-ping. Thermal Simulation on Hot Deformation Behavior of ZK60 Magnesium Alloy[J]. Journal of Materials Engineering, 2009, 0(11): 45-50.
The microstructure evolution of ZK60 magnesium alloy was investigated by hot compressive tests on Gleeble-1500 thermal simulation test machine in temperatures range from 473K to 723K and strain rates of 0.001-1s-1.The effect of deformed degree,temperature and rate on the behavior of dynamic recrystallization was analyzed.The mechanism of dynamic recrystallization nucleation was discussed.The result shows that dynamic recrtystallization is the mainly softened mechanism when ZK60 Mg alloy was deformed at high temperature.Many dynamic recrystallization grains that formed easy ductile shear zone were observed on the grain boundaries when ε>0.24 and T=623K.The deformed temperature has an important effect on the grain size of ZK60 Mg alloy dynamic recrystallization.The grain size of dynamic recrystallization is larger than 25μm at T>623K.The dynamic crystallization nucleus of ZK60 Mg alloy form on the grain boundaries arched zone.The combination and growth of subgrain occurred with strain capacity increasing.The long banding subgrains quickly grow and nucleate on the shear zone.
HUANG Hai, HUANG Wei-gang. Study on Dynamic Mechanical Properties of Magnesium Alloy AZ61[J]. Journal of Materials Engineering, 2009, 0(11): 51-54.
The Split Hopkinson Pressure Bar(SHPB) was used for investigating dynamic mechanical properties of extrusion formed AZ61 alloy.The samples after impact were analized by scanning electron microscope(SEM) and metallography.The alloy's dynamic crack performance and plastic deformation mechanism at room temperature were discussed.The results showed that the alloy performed strain hardening under high strain rate compression.The samples were brittle ruptured under impact basically,but a few dimples can also be found on the fracture section.Twinning and glide coacted during the alloy's plastic deformation.Remelting was observed under SEM while the strain rate of the test reached 2.3?103.
YANG Ji-nian, LI Zi-quan. Investigation on the Compressive Performances and Energy Absorption Behavior of Ternary Composite Foam of PP/POE/SGE[J]. Journal of Materials Engineering, 2009, 0(11): 55-58.
The compressive properties of polypropylene(PP)/ethylene-1-octene copolymer(POE)short glass fiber(SGF) ternary foamed composites were tested and analyzed under the quasi-static and uniaxial compressive loading condition.The effects of mass fraction of SGF on the modulus,yield strength and energy absorption behavior were discussed.The results show that the compressive stress-strain curves of PP/POE/SGF foamed composites are consisted of three typical stages: elastic behavior,plastic plateau and densification.The modulus,yield strength and capability of energy absorption are enhanced by the addition of suitable SGF loading.The energy absorption efficiency of foamed composites is improved only when the incorporation of SGF beyond 20% in this investigative range and the reinforcement effect is not remarkable as capability of energy absorption shown.
WU Jie, HAN Fu-sheng, CUI Hong-zhi, CHI Jing, YAO Shu-yu. Relaxation Correlated to Vacancies in B2 Fe-Al Alloys[J]. Journal of Materials Engineering, 2009, 0(11): 59-64.
The internal friction behaviors of air-cooled B2 Fe-Al alloys were examined to understand the movement of atomic defects.Two internal friction peaks were found at around 210℃(P1 peak) and 410℃(P2 peak),respectively.Both the peaks showed relaxational nature and they are correlated to the concentration of vacancies.It is suggested that the P1 peak originates from the reorientation of the divacancies(VVFeVAl),the P2 peak from the interactions between antisite atoms and Fe vacancies.For the Fe-rich B2 Fe-Al alloys,the P2 peak is attributed to the reorientation of the triple defects(2VVFeVAl);for the Al-rich alloys,however,it is caused by the stress-induced migration of Al antisite atoms among the Fe vacancies.
YANG Bi-ling, ZHANG Hui-ping, ZHANG Tong-hua, ZHUANG Xing-min, YAN Xiong. Progressive Damage Analysis of Thermoplastic Self-reinforced Polyethylene Composites Considering the Material Nonlinearity[J]. Journal of Materials Engineering, 2009, 0(11): 65-68,98.
A progressive damage model has been developed for thermoplastic PE/PE laminates subjected to static tensile loading,by considering the nonlinear properties of unidirectional composites in longitudinal,transverse and shear stress-strain behavior as piecewise linear-elastic properties.Finite element method was used for simulating the progressive failure of UHMWPE/LDPE laminates to study the damage mechanisms.It was showed that longitudinal nonlinearity of the composites had remarkable effect on the nonlinear behavior of the laminates.The nonlinearity of composites and structures was conveniently and effectively included by the piecewise linear elasticity treatment.Combining with the progressive failure analysis,damage modes such as matrix cracking,fiber-matrix shearing and fiber fracture were revealed and the damage propagation was presented.The analytical prediction showed excellent agreement with the experimental data,proving that the numerical modeling is valid.
PIAO Zhong-yu, XU Bin-shi, WANG Hai-dou, PU Chun-huan. Investigation of Contact Fatigue Mechanism of Plasma Spraying Fe-based Coating[J]. Journal of Materials Engineering, 2009, 0(11): 69-73.
The contact fatigue mechanism of supersonic plasma sprayed Fe-based alloy coating was investigated.The contact fatigue experiments of coating were conducted by a ball-and-disc contact fatigue tester.Three typical failure modes were obtained after the analysis of worn surface morphologies,i.e.abrasion,spalling and delamination.And the failure mechanisms were investigated,respectively.The results showed that the abrasion failure is associated with asperity contact,the spalling failure is associated with micro-defects near the surface,and the delamination failure is associated with the distribution of shear stress in the coating.
ZHU Tu-fu, SHEN Li-ru, XU Gui-dong, JIN Fan-ya. Structure and Properties of Cr-containing Hydrogenated Diamond-like Carbon Films Deposited by DC Filtered Cathodic Vacuum Arc Technology[J]. Journal of Materials Engineering, 2009, 0(11): 74-79.
Cr-containing hydrogenated diamond-like carbon(Cr-DLC) films were deposited on stainless steel plate,monocrystalline silicon wafer and microscope slide glass by DC filtered cathodic vacuum arc technology.The composition,structure and properties of Cr-DLC films were investigated by spectroscopic ellipsometer,X-ray photoelectron spectroscopy(XPS),powder X-ray diffraction(XRD),spectrophotometer,Raman spectroscopy,nanoindenter,ball-on-disk tribometer,Rockwell apparatus and optical microscope.It was shown that the content of C is 89% in the film deposited on silicon wafer and the content of sp3 bonding carbon atoms in the C element is 55.15%.The Raman spectra of the film deposited on stainless steel plate has the typical characteristics of DLC.The hardness and elastic modulus of the film deposited on stainless steel plate are 16.01 GPa and 142.72 GPa.The friction coefficient of the film deposited on stainless steel plate is about 0.1,the film also exhibits excellent wear resistance and the adhesion to substrate is very well.
LUO Da-wei, SHEN Zhuo-shen. Wetting Behavior of Borosilicate Glass on Kovar Alloy[J]. Journal of Materials Engineering, 2009, 0(11): 80-83,87.
The wettability of borosilicate glass on Kovar with oxides of FeO and FeO+Fe3O4 respectively was studied as a function of holding time at 1000℃ by the sessile drop method.The contact angle and drop diameter were measured by the VHX-100K digital microscopy.The surface micrographs of halo and cross-sections of glass and kovar were investigated by SEM,and the chemical composition of halos was studied by EDS analysis.The results show that the contact angle all decreases as the time increases,and the final contact angles are 25° and 23° for FeO and FeO+Fe3O4,respectively.Two halos are observed in the wetting process.By analyzing the change of contact angle,halo and drop diameter,wetting process could be divided into three stages: initial period,spreading period and equilibrium period.
WANG Sheng-min, ZHAO Xiao-jun, HE Ming-yi, LIU Li, PEI He-zhong, TAN Rong. Effects of Particle Shapes of Zinc on the Properties of Mechanically Deposited Coating[J]. Journal of Materials Engineering, 2009, 0(11): 84-87.
Zinc coatings were prepared by mechanically deposition method with spherical zinc particle and lamellar zinc particle,respectively.SEM and XRD were employed to study the structure and the phase constitutes of the coating.Surface hardness was studied by surface Rockwell hardness tester.The effects of particle shapes of zinc powders on the coating anticorrosion property was studied by salt spray test and potentiodynamic polarization.The results show that particle shape of zinc powders has no effects on surface hardness and phase constitutes of the coating.The corrosion resistance of coating obtained by lamellar zinc particle is better than that obtained by spherical zinc particle.
MA Hai-quan, YU Yang, JIANG Tao, TAO Chun-hu, LI Ming. Failure Analysis of Gear in a Wind Power Generator[J]. Journal of Materials Engineering, 2009, 0(11): 88-91.
The gear case in a wind power generator failed during service,and it was found that a tooth of a gear in the gear case fractured.In order to find out the fracture cause of the gear,macro and micro observation was carried out on the fractured gear,energy spectrum analysis was conducted on the matrix and the fracture source region of the gear,surface residual stress was tested,and finally,fracture quantitative analysis was carried out.The results show that the failure mode of the gear is bending fatigue fracture.The fracture of the gear is caused by slag inclusions at the position of the gear,and has nothing to do with the design,material,and operation of the gear.
CHEN Rong-guo, FANG Xiao-ming, XIAO Li-ren, CHEN Qing-hua. Advancement of Hyperbranched Polyesteramides[J]. Journal of Materials Engineering, 2009, 0(11): 92-98.
As a small embranchment of Hyperbranched polymer(HBP),hyperbranched polyesteramide(HBPEA) that has been excitingly explored in recent years,can be facilely synthesized by introducing commercial monomer,and integrate the excellent mechanical properties of polyamides,the biodegradability of polyesters and the unique properties of HBP.Promisingly,HBPEA have a wide application future in numerous areas.General idieas to fabricate hyperbranched macromolecule,main methods for synthesizing HBPEA and some applications of HBPEA,were concerned.
