QU Min, LIU Lin, ZHANG Wei-guo, ZHAO Xin-bao, ZHANG Jun, FU Heng-zhi. Research of Dendrite/Cellular Interfacial Transitional Velocity in Directionally Solidified Al-4%Cu Alloy[J]. Journal of Materials Engineering, 2008, 0(12): 1-5.
The transition from cellular to dendrite was obtained at the spindle of tip radius by comparing experimental and theoretical study on Al-4%Cu alloy during directional solidification.It was found that the tip radius fell quickly in cellular stage but fell slowly in dendrite stage.The KGT(W.Kurz,B.Giovanola and R.Trivedi) model and non-equilibrium effect were applied to research the tip radius and interface temperature in order to obtain the transitional characteristic from dendrite to cellular.The results indicated that the tip radius and interface temperature were both decreased with increasing withdrawal rate,after reached the critical points,finally turned to rise sharply.It was eventually obtained that the transition from dendrite to cellular was occurred at the spindle of tip radius and temperature,that was the tip radius and tip temperature reached minimum,VRmin and VTmin.Moreover,solute trapping became obvious during the transition,which led to decrease of microsegregation.
LI Jia-rong, SHI Zhen-xue, YUAN Hai-long, LIU Shi-zhong, ZHAO Jin-qian, HAN Mei, LIU Wei-wei. Tensile Anisotropy of Single Crystal Superalloy DD6[J]. Journal of Materials Engineering, 2008, 0(12): 6-10.
The tensile properties and tensile fracture of the second generation single crystal superalloy DD6 with,and orientation were studied.The results show that DD6 alloy has tensile anisotropy,when temperature is higher than 850℃ the ultimate tensile strength and yield strength of DD6 alloy with orientation are higher than those with and orientation,and there are the fracture features characteristic of quasi-cleavage and dimple in DD6 alloy with,and orientation.
JIA Li-xiao, ZHANG Yong-zhen, LI Jian, SUN Le-min. Research on Tribology Property of Carbon Soaked by Metal with Current[J]. Journal of Materials Engineering, 2008, 0(12): 11-14,18.
With the couple of carbon soaked by metal and chrome bronze,the tribology property of carbon soaked by metal with current was studied.The results showed that current,velocity and load were important factors for tribology property of carbon soaked by metal with current.Under the condition of stated current,the coefficient and wear rate increased with the increased of velocity but decreased with the increased of load.Under the condition of stated load,the friction coefficient and the wear rate increased with the increased of current.Contrast with no current,the friction coefficient of carbon soaked by metal decreased and the wear rate increased obviously.
LI Shun, BAI Shu-xin, ZHANG Hong, CHEN Ke, XIAO Jia-yu. Nanocomposite Nd2Fe14B/α-Fe Magnets with Ti and C Additions[J]. Journal of Materials Engineering, 2008, 0(12): 15-18.
The effects of Ti and C additions on the magnetic properties of Nd9.4Fe79.6B11 alloy were investigated.The results showed that marked enhancement of coercivity was gained without sacrificing much remanence with the addition of Ti and C.Excellent magnetic properties of Br=0.91T,Hcj=975.6kA/m,and(BH)max=135.4kJ/m3 were achieved in Nd9.4Fe75.6Ti4B10.5C0.5 alloy ribbons.In comparison with bonded MQ-D magnets,low cost bonded Nd9.4Fe75.6Ti4B10.5C0.5 magnets with a density of 6.1g/cm3 and high magnetic properties of Br=0.68T,Hcj=975kA/m,and(BH)max=76 kJ/m3 were also achieved.
LI Yu-chun, CHENG Ke-ming, SHEN Wei, LIU Qiang. Damage Analysis of Concrete Structure by Underwater Shock[J]. Journal of Materials Engineering, 2008, 0(12): 19-23.
The interaction of shallow water shock waves and concrete structure was investigated by field explosion experiments,and the damage mechanism of concrete material under shallow water shock waves was discussed.The experimental and analytical results showed that the function of shallow water shock waves to concrete structure was involved in compression and tension of stress wave in the concrete structure.Due to the fluidity and isotropy of water material,the concrete structure was functioned by ambient pressures.The concrete structure was in multi-axial stress states,and the multi-axial stress states was the key function of failure and fracture of concrete material under shallow water shock waves.
GUO Feng, LI Jie, LI Zhi, WANG Jun-li, GU Li-xin, WANG Rui. SEM In-situ Observations to Crack in Rare-earth Inclusions in AerMet100 Steel Under Stretch Tension[J]. Journal of Materials Engineering, 2008, 0(12): 24-29.
The appearance and size of rare-earth inclusions in the AerMet100 steel were observed with SEM,and the micro-mechanical behavior was investigated by the In-situ observations.The results showed that inclusions were spherical or ellipsoidal,and the cracks initiated firstly in the inner of inclusion.The stress criteria of inclusion crack initiation were established,and crack propagation was difficult to extend.The results of numerical simulation of single tension and the theoretical calculations were consistent with the In-situ stretch.
YU Xiang, WANG Jun, YANG Li-hui, LI Jun-qing, ZNANG Mi-lin. Study of Anticorrosion Mechanisms on Zn-Al-[V10O28]6- Hydrotalcite for Mg Alloy[J]. Journal of Materials Engineering, 2008, 0(12): 30-33.
As an environmental-friendly new style pigment for Mg alloy corrosion protection,decavanadate([V10O28]6-) interlayer Zn-Al hydrotalcite(Zn-Al-[V10O28]6-) was prepared by co-precipitation method,which can absorb corrosive anion and release the inhibitor of [V10O28]6-ion.The adsorption and anticorrosion mechanisms of the hydrotalcite were investigated by N2 adsorption-desorption,Inductively Coupled Plasma(ICP) and polarisation curves respectively.The corrosion protection properties for Mg alloy based on the Zn-Al-[V10O28]6-/epoxy coatings were investigated by salt spray testing.The results demonstrated that the material can afford doubly function of anodic passivity and barrier protection and had excellent corrosion resistant property.
YE Rong-chang, ZONG Cui, LONG Yi. Research on Preparation of Magnetic Regenerator Material HoCu2 Atomized Powders[J]. Journal of Materials Engineering, 2008, 0(12): 34-37.
The powders of magnetic regenerator material HoCu2 was prepared by rotating disk centrifugal atomization,and the phase and microstructure of powders were studied.Results showed that the powders were consisted of HoCu2 single phase.And the particle size obey normal distribution.The proportion of powders less than φ154μm was near 30%.While the yielding rate of powders between φ154μm-300μm was more than 61%,these powders were mainly spherical.The grain size increased with increased particle size.The proportion of powders greater than φ300μm was as low as 9%,most of which were flakes with microstructure of fine equiaxed grains.
GUO Zi-bin, ZHAO Hong-sheng, HU Hong-po. Photo-catalytic Properties of SiO2/TiO2 Composite Films[J]. Journal of Materials Engineering, 2008, 0(12): 38-40,45.
The SiO2/TiO2 composite films were prepared on glass substrates by sol-gel technology and dip-coating process,and were characterized by SEM,XPS and UV-Vis transmittance and absorption spectra.The photo-catalytic activity of the composite films was studied through the degradation experiment of methyl blue under UV light.The results showed that the SiO2 film on the glass substrates can reduce Na+ ion and Ca2+ ion content in the TiO2 film and make for the crystals growth of the TiO2 thin film.Thereby,the photo-catalytic activity of the TiO2 film was improved.
LI Hong-ying, SUN Yuan, WANG Xiao-feng, TANG Yi, ZENG Zai-de, WANG Fa-yun, ZHENG Zi-qiao. Effect of Hot Treatment on Mechanical Properties and Microstructure of a New Type Al-Cu-Li Alloy[J]. Journal of Materials Engineering, 2008, 0(12): 41-45.
Basal investigation of a new type Al-Cu-Li alloy was carried out.The peak-aging of the new type Al-Cu-Li alloy was determined through tensile tests and the Transmission Electron Microscopy(TEM) was used to investigate the microstructure of the experimental alloy.Precipitates δ′,T1,σ,θ′,θ″were found in the alloy.The mechanical properties changing with different kinds and amount of precipitates were analyzed.The work showed that the compound effect of precipitation δ′and θ′attribute to the matrix strengthening and that the strengthening effect of precipitation σ was more effective than precipitation θ′.Precipitation θ″kept decreasing with aging process and disappeared at last.The qualitative relationship of mechanical properties and microstructure was established.
WANG Zhi-hui, ZHAO Nai-ren, LI Jin-guo, HOU Gui-chen, JIN Tao, SUN Xiao-feng, HU Zhuang-qi. Effects of Heat Treatment on Microstructures and Stress Rupture Properties in SRR99 Ni-base Single Crystal Superalloy[J]. Journal of Materials Engineering, 2008, 0(12): 46-50.
The effects of solution and aging heat treatment temperatures on the microstructures and stress rupture properties in SRR99 single crystal Ni-base superalloy were investigated.The microstructures were examined by SEM and OM.Creep tests were carried out at a GWT304 constant load high temperature creep-testing machine,the loading condition being 1010℃/248MPa.The results showed that,with the enhancing of primary aging temperature,the size of secondary γ′ phase increased and the volume fraction of γ′ phase increased firstly with subsequent decreasing.The higher the solution treatment temperature was,the lower the amount of remained eutectic γ′ and the segregation of alloy elements were.The stress rupture lives of SRR99 single crystal superalloy increased firstly and then decreased with the increasing of solid solution treatment temperature.
SHUAI Ge-wang, FANG Ping, GUO Zheng-hua, LU Bai-ping. Aging Treatment of Cu-Fe Supersaturated Solid Solution Prepared by Mechanical Alloying[J]. Journal of Materials Engineering, 2008, 0(12): 51-54.
The effect of aging treatment on hardness and electrical conductivity of Cu-xFe(x=1,2,4,mass fraction/%) supersaturated solid solutions prepared by mechanical alloying was investigated.The X-ray results showed that the solubility of Fe in Cu increased due to the internal strain and microstructural refinement caused by ball milling.The solubility of Fe in Cu can be extended to 4% after 32h ball milling.Meanwhile,the copper grain size and lattice parameter decreased to 20nm and 0.3621nm respectively.The aging treatment can promote the decomposition of the supersaturated solid solution which decreased the hardness and improve the electrical conductivity.The microhardness of the cold press formed Cu-4Fe alloy powders decreased from 175 to 96,and the electrical conductivity increased from 35%IACS(International Annealed Copper Standard) to 60%IACS.
CUI Xu-mei, HUANG Zai-chun, CHEN Xiao-e. Preparation of TiO2 Films Doped with Rare-earth Elements and Its Optical Property[J]. Journal of Materials Engineering, 2008, 0(12): 55-57.
TiO2 films doped with Y3+ and Ho3+ ions were prepared with sol-gel method.X-ray diffraction analysis showed that the films crystallized well with anatase crystalline.AFM analysis showed the films had nanocrystallines.UV-Vis absorption analysis of the films indicated that the films doped with Y3+ and Ho3+ ions had higher absorbance in UV district,and the films had a red-shift of absorption edge in visible district,the films doped with Y3+ ion had higher absorbance than the films doped with Ho3+ ion with the same ion concentration.
NING Yong-quan, YAO Ze-kun, YUE Tai-wen, GUO Hong-zhen, GUO Yan-li. Investigation on Repeated Firing Hot-die Forging of GH4133A Alloys[J]. Journal of Materials Engineering, 2008, 0(12): 58-61.
The Repeated Firing hot-die Forging(RFF) on GH4133A alloy processed under different conditions was carried out,and the tensile tests were investigated at room and 700℃ temperature.The results indicated that grain size and tensile properties at room temperature significantly improved with repeated firing forging about 10%,and tensile properties at 700℃ processed under two fires forged about 30% was better to others.Tensile properties at 700℃ of GH4133A alloy processed at 1160℃ was superior to that of 1080℃.
YAN Lu-ting, WANG Peng, WU Hong-peng, SI Wen-jie. Preparation of Layered K2Ti4O9 and Study Its Acid Exchange and Exfoliation Reaction[J]. Journal of Materials Engineering, 2008, 0(12): 62-64.
Three ways including high temperature solid state reaction,stearic acid and potassium stearate were used to produce ultrafine layered potassium titanate.XRD and SEM were used to characterize the crystal structure and morphologies.The effects of different reaction processes on size and structure of products were studied.The advantages and disadvantages of different methods were compared.A preliminary study was also conducted to acid exchange,exfoliation of K2Ti4O9.
FU Xian-hui, SHEN Zhi-gang, CAI Chu-jiang, MA Shu-lin, XING Yu-shan. Effect of Preparation Parameters on Properties of Spray Dried Ammonium Dihydrogen Phosphate Fire-extinguishing Particles[J]. Journal of Materials Engineering, 2008, 0(12): 65-69.
Superfine spherical hollow hydrophobic ammonium dihydrogen phosphate(NH4H2PO4) fire-extinguishing particles were produced by a spray drying method and modified in situ with silicon oil emulsion.The results indicated that the particles prepared at the inlet gas temperature of 180℃,200℃and220℃ were composed of NH4H2PO4.In the absence of carboxy methyl cellulose sodium(CMC),some nonspherical particles were formed.When 0.5% or 1.0% of CMC was added,the resulting particles had a good spherical shape and hollow particles increased.With an increase in the mass fraction of CMC,the bulk density of particles decreased.9.0% silicon oil emulsion was the optimal proportion for improving the hydrophobic performance of particles.X-ray Photoelectron Spectroscopy(XPS) analysis suggested that the hydrophobicity of particles was attributed to the migration of silicon oil emulsion to the surface of particles during the spray drying process.Fire-extinguishing test showed the extinguishing capability of superfine spherical hollow NH4H2PO4 fire-extinguishing particles prepared by spray drying was improved.
LIANG Xing-quan, YUAN Dao-sheng, LI Ke-wen, ZHU Yuan-chen, ZHANG Zhen, SONG Jiang-xuan. Effect of Organic Montmorillonite on Stability of PE Composite[J]. Journal of Materials Engineering, 2008, 0(12): 70-72,77.
Organic montmorillonite(O-MMT) was formed through the way that betaine ions exchanged with Na+ in montmorillonite.Then the PE/O-MMT composites were synthesized through melt intercalation and processed by the photo-oxidation degradation in artificially accelerated aging oven.The intrinsic viscosities of the PE in the composites films which contained different contents of O-MMT were analyzed respectively and the Scanning Electron Microscopy(SEM) was used to analysis the morphology of PE/O-MMT composites films containing 0%,4% O-MMT.The results indicated that the photo-oxidation degradation stability of the PE in the composites films was higher than that of pure polyethylene film.
WANG Hai-tao, ZHANG Guo-ling, YU Hua-shun, WANG Shao-qing, MIN Guang-hui. Effects of Chromium,Aluminium and Silicon on Oxidation Resistance of Fe-base Superalloy[J]. Journal of Materials Engineering, 2008, 0(12): 73-77.
The effects of chromium,aluminium and silicon on the oxidation resistance were studied by orthogonal experiment method.The results show that the content of Cr,Al,Si in test alloys for stable oxidation resistance should be added more than 17%Cr,4%Al and 1.5%Si respectively.The most affecting element for oxidation resistance is Si among stoichiometric Cr,Al and Si,the following one is Al,and the last one is Cr.The flat and compact structure,fine and even grains endow it with good oxidation resistance,otherwise the scales are bad in oxidation resistance.High-temperature oxidation resistance depends on the composition of the scales on test alloys.The compounded scales of Cr2O3,Al2O3,SiO2 and Fe(Ni)Cr2O4 possess strong oxidation resistance at 1250℃,but it become poor without Al2O3 or SiO2.
LIU Ping, YANG Jun-hong. Investigation of Digital Spectroscopic Analysis on Copper in Ferroalloy[J]. Journal of Materials Engineering, 2008, 0(12): 78-80.
The visible light spectrum was studied on copper in ferroalloy by digital analysis system.The digital spectra were simulated by computer and digital spectra were shot with digital analysis system.The researches were made on character of Cu510.55 line groups in ferroalloy and the analysis charts were obtained.The method was developed for spectroscopic analysis of copper in ferroalloy.The results can meet the qualitative and the quantitative analysis on copper in ferroalloy,can be used to exactly examine alloy and avoid the commixing of material on spot.
