Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

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      28 March 2005, Volume 21 Issue 02 Previous Issue    Next Issue
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    Research Articles
    An Extended Chaboche's Viscoplastic Law at Finite Strains: Theoretical and Numerical Aspects
    R.C.Lin, W.Brocks
    J. Mater. Sci. Technol., 2005, 21 (02): 145-147. 
    Abstract   HTML   PDF (261KB)
    This paper presents a newly extended Chaboche's viscoplastic law at finite strains, so that the classical Chaboche's theories can be applied to the physical and numerical simulation of metals processing and behavior description of spatial metal structures. The extension is based on a new dissipation inequality at finite strains. The evolution equations are formulated in terms of the corotational rates of the logarithmic elastic strain and the strain-like internal variable conjugate to the back stress as well as the material time derivative of the accumulated plastic strain. The stress equation is expressed on the hyperelastic theory. Therefore, the possible inconsistency with elasticity, caused by the hypoelastic equations, is completely removed. A set of numerical examples with finite deformations are presented to prove the effectivities of the new model and numerical algorithms.
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    Experimental Study and Finite Element Polycrystal Model Simulation of the Cold Rolling Textures in a Powder Metallurgy Processed Pure Aluminum Plate
    Liqing CHEN, Naoyuki Kanetake
    J. Mater. Sci. Technol., 2005, 21 (02): 148-154. 
    Abstract   HTML   PDF (961KB)
    Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however, the textures in powder metallurgy (PM) processed aluminum has been rarely reported. In this article, a pure aluminum plate was prepared $via$ PM route. The starting billet was first produced with uni-axially cold compaction and flat hot-extrusion and then followed by cold rolling processes. The hot-extruded and cold rolling deformation textures of the pure PM aluminum at 50%, 80% and 90% cold rolling reductions were studied by orientation distribution functions (ODFs) analysis. The finite element polycrystal model (FEPM) was finally utilized to simulate the cold rolling textural evolution at various stages of cold rolling. In FEPM simulation, the initial hot-extruded textures were taken into account as inputs. The results showed that typical β-fiber texture formed in pure PM aluminum with the cold rolling reduction increased till 80%, and there was not much change after excessive cold rolling deformation. Homogeneous slip is not the only deformation mode in PM processed pure aluminum plate at over 80% cold rolling reduction. The experimental results were qualitatively in good agreement with the simulated ones.
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    Experimental Investigation and Numerical Simulation of the Grain Size Evolution during Isothermal Forging of a TC6 Alloy
    Miaoquan LI, Shankun XUE, Aiming XIONG, Shenghui CHEN
    J. Mater. Sci. Technol., 2005, 21 (02): 155-160. 
    Abstract   HTML   PDF (677KB)
    Hot compression was conducted at a Thermecmaster-Z simulator, at deformation temperatures of 800~1040℃, with strain rates of 0.001~50 s-1 and height reduction of 50%. Grain size of the prior α phase was measured with a Leica LABOR-LUX12MFS/ST microscope to which QUANTIMET 500 software for image analysis for quantitative metallography was linked. According to the present experimental data, a constitutive relationship for a TC6 alloy and a model for grain size of the prior α phase were established based on the Arrhenius' equation and the Yada's equation, respectively. By finite element (FE) simulation, deformation distribution was determined for isothermal forging of a TC6 aerofoil blade at temperatures of 860~940℃ and hammer velocities of 9~3000.0 mm/min. Meanwhile, the grain size of the prior α phase is simulated during isothermal forging of the TC6 aerofoil blade, by combining FE outputs with the present grain size model. The present results illustrate the grain size and its distribution in the prior α phase during the isothermal forging of the TC6 aerofoil blade. The simulated results show that the height reduction, deformation temperature, and hammer velocity have significant effects on distribution of the equivalent strain and the grain size of the prior α phase.
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    Graphitization of Spray-formed Ultrahigh Carbon Steels Containing Si during Hot Rolling
    Guangmin LUO, Jiansheng WU, Junfei FAN, Haisheng SHI, Yijian LIN, Jingguo ZHANG
    J. Mater. Sci. Technol., 2005, 21 (02): 161-164. 
    Abstract   HTML   PDF (336KB)
    The graphitization behavior of ultrahigh carbon steels containing Si in hot rolling processes was investigated. The graphite stringers went mostly through the small pores and generally paralleled to the rolling direction. The influence of alloy elements on graphitization was estimated based on thermodynamics, which showed that Si content was important for graphitization. Graphite stringers nucleated at small pores and grew with carbon diffusion during hot rolling. Alloy contents, pores and hot deformation at γ+Fe3C phase range were the key factors for the formation of graphite. The probable effect of deformation on graphite formation during hot rolling was discussed in this paper.
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    Model Building of the Initial Crown Effect Rate in 4-High Mill
    Jianzhong XU, Dianyao GONG, Wencai ZHANG, Xianwen CHANG, Xianghua LIU, Guodong WANG
    J. Mater. Sci. Technol., 2005, 21 (02): 165-169. 
    Abstract   HTML   PDF (574KB)
    The code for calculating the crown effect rate of hot strip steel was developed using the effect function method. The effect of the initial crown on the crown of the product in hot strip rolling was investigated. The coefficients of a polynomial of degree six for calculating the base value of initial crown effect rate in 4-high mill were determined and the compensation factors of per unit width rolling force, bending force, work roll crown and draft on the initial crown effect rate were given. The difference between the calculation result by established model and theoretical value obtained by effect function method was 4.88 μm when the strip width was 1.85 m.
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    Influences of Casting Pressure Conditions on the Quality and Properties of a Magnesium Cylinder Head Cover Die Casting
    Wenhui LIU, Yangai LIU, Shoumei XIONG, Baicheng LIU, Y.Matsumoto, M.Murakami
    J. Mater. Sci. Technol., 2005, 21 (02): 170-174. 
    Abstract   HTML   PDF (597KB)
    Casting pressure conditions have great influences on the casting defects, such as gas porosity, shrinkage porosity and gas holes. A Mg cylinder head cover die casting was used to experimentally study the influences of casting pressure, the loading time and the piston position of pressure intensification on the variation of pressure and the quality of casting. The results show that casting pressure, the loading time and the piston position of pressure intensification have great influences on the pressure variations in the mold, the quality and performance of casting. The external quality, the density and the tensile strength of casting were improved with the increase of casting pressure and the piston position of pressure intensification and the decrease of the loading time of pressure intensification.
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    Processing and Microstructural Evolution of Superalloy Inconel 718 during Hot Tube Extrusion
    Shihong ZHANG, Zhongtang WANG, Bing QIAO, Yi XU, Tingfeng XU
    J. Mater. Sci. Technol., 2005, 21 (02): 175-178. 
    Abstract   HTML   PDF (458KB)
    The processing parameters of tube extrusion for superalloy Inconel 718 (IN 718), such as slug temperature, tools temperature, choice of lubricant, extrusion ratio and extrusion speed, were determined by experiment in this paper. An appropriate temperature range recommended for the slug is 1080~1120℃, and the temperature range recommended for the tools is 350~500℃. The microstructural evolution of superalloy IN 718 during tube extrusion was analyzed. With the increase of the deformation the cross crystal grains were slightly refined. While the vertical crystal grain is elongated evidently and the tensile strength increased along the axial rake. Glass lubricants have to be spread on the slug surface after being heated to 150~200℃, vegetable oil or animal oil can be used as the lubricant on the surface of the tools to reduce the extrusion force remarkably.
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    Preparation and Characterization of Polyaniline Nanofibers by Template-free Method
    Xuemei GUO, Kun LUO, Nanlin SHI
    J. Mater. Sci. Technol., 2005, 21 (02): 179-182. 
    Abstract   HTML   PDF (444KB)
    In the presence of p-toluene sulfonic acid (TSA) as a dopant, polyaniline (PAni) nanofibers, (about 80~165 nm in diameter) were successfully synthesized with a chemical template-free method. It was found that the formation probability, morphology, and diameter of the resulting PAni-TSA nanofibers were sensitive to the synthetic conditions, such as reaction temperature, the molar ratio of TSA to aniline, and the concentration of TSA in the polymerization media. The molecular structure was characterized by using the FT-IR, Raman spectra and X-ray diffraction, which shows that the main chain structure of PAni-TSA nanofibers was in agreement with that of granular PAni.
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    Characterization of ZnO Based Varistor Derived from Nano ZnO Powders and Ultrafine Dopants
    Weizhong YANG, Dali ZHOU, Guangfu YIN, Runsheng WANG, Yun ZHANG
    J. Mater. Sci. Technol., 2005, 21 (02): 183-186. 
    Abstract   HTML   PDF (563KB)
    Nanosized ZnO powders were prepared with a two-step precipitation method. The average size of ZnO particles was about 80 nm and their size distribution was narrow. Combining with ultrafine additive powders, ZnO base varistor was produced via an oxide mixing route. ZnO varistor derived from normal reagent grade starting materials was investigated for comparison purpose. Outstanding microstructure of the ZnO varistor derived from nanosize ZnO powders and ultrafine dopants was obtained: uniform distribution of fine ZnO grains (less than 3 microns), grain boundary and the dopant position. Higher varistor voltage (U=492 V/mm) and nonlinear coefficient (α=56.2) as well as lower leakage current (I L=1.5 μA) were achieved. The better electrical properties were attributed to the uniform microstructure, which in turn led to stable and uniform potential barriers. Also this improved technique is more feasible for producing ZnO nanopowders and resulting varistor in large scales.
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    Preparation and Characterization of Palladium Colloidal Nanoparticles by Thermal Decomposition of Palladium Acetate with Microwave Irradiation
    Yixian CHEN, Baolin HE, Hanfan LIU
    J. Mater. Sci. Technol., 2005, 21 (02): 187-190. 
    Abstract   HTML   PDF (428KB)
    A series of solvent-stabilized palladium colloidal nanoparticles were prepared $via$ thermal decomposition of palladium acetate methylisobutylketone (MIBK) solution in the presence of alkali and alcohol with microwave irradiation. The colloidal nanoparticles were characterized with TEM, XPS and XRD. The average diameters of nanoparticles increase from 30 to 40~nm with the increase in concentration of palladium acetate. TEM and XRD observation demonstrated that the palladium colloidal nanoparticles were clusters agglomerated from hundreds of smaller palladium crystallines with size of 3~4 nm. The influence of the concentrations of alkali and alcohol to the particle size was also discussed.
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    Preparation of (Ti, Sn)O2 Nano-Composite Photocatalyst by Supercritical Fluid Dry Combination Technology
    Jingchang ZHANG, Qing LI, Weiliang CAO
    J. Mater. Sci. Technol., 2005, 21 (02): 191-195. 
    Abstract   HTML   PDF (342KB)
    A series of TiO2-SnO2 nano-sized composite photo-catalysts containing Sn (9.3%~30.1%) were prepared from TiCl4 and SnCl4•5H2O by using sol-gel, supercritical fluid dry and solid-phase reaction (SCFD) combination technology. Characterizations with X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed that, in addition to anatase type TiO2, a new active phase (Ti, Sn)O2 (with particle size of 2.0~4.3 nm) formed, and there were no SnO2 crystals observed in the range of the doping concentration studied. Photo-catalytic reaction of phenol was used as a model reaction to evaluate the catalytic activities of the obtained catalysts. Compared with pure TiO2 or Ti-Sn catalyst prepared with general sol-gel method, Ti-Sn nano-composite photo-catalyst thus obtained showed significant improvement in catalytic activity. The photo-catalytic degradation rate of phenol could reach as high as 93.5% after 7 h. The preparation conditions of the new phase (Ti, Sn)O2 were investigated and its catalytic mechanism was proposed. The photo-catalytic particles prepared using SCFD combination technology exhibited small particle size, large surface area and high activity.
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    Modelling of Equilibrium Grain Boundary Solute Segregation under Irradiation
    Shenhua SONG, R.G.Faulkner, P.E.J.Flewitt, Luqian WENG
    J. Mater. Sci. Technol., 2005, 21 (02): 196-200. 
    Abstract   HTML   PDF (313KB)
    Both radiation-induced excess vacancies and solute-interstitials may enhance solute diffusion. The radiation-enhanced solute diffusion promotes the kinetic process of equilibrium segregation. This effect is especially considerable in the low temperature range. As a complement to modelling of radiation-induced non-equilibrium segregation, the radiation-created vacancy and solute-interstitial-accelerated equilibrium grain boundary solute segregation were theoretically treated. The models were applied to phosphorus segregation in α-Fe subjected to neutron irradiation.
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    Surface Tension of Molten Ni and Ni-Co Alloys
    Feng XIAO, Liang FANG, Kiyoshi NOGI
    J. Mater. Sci. Technol., 2005, 21 (02): 201-206. 
    Abstract   HTML   PDF (558KB)
    Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773~1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The error of the data obtained was analyzed. The surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys decreases with increasing temperature. The influence of Co on the surface tension of Ni-Co alloys is little in the studied Co concentration range.
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    Zirconium-Induced Softening in Hyperstoichiometric Ni3Al
    Yufang LI, Jianting GUO, Hengqiang YE
    J. Mater. Sci. Technol., 2005, 21 (02): 207-210. 
    Abstract   HTML   PDF (449KB)
    The room temperature compressive properties and microhardness of Ni3Al alloys doped with Zr were studied. For the hypostoichiometric Ni3Al alloys, the compressive strength and microhardness increased with an increase in Zr content, while softening behavior induced by doping with a certain amount of Zr was observed in hyperstoichiometric Ni3Al alloy. Possible mechanisms for the softening effect were suggested.
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    Martensitic Transformation and Magnetic-Field-Induced Strain in Magnetic Shape Memory Alloy NiMnGa Melt-Spun Ribbon
    Shihai GUO, Yanghuan ZHANG, Jianliang LI, Baiyun QUAN, Yan QI, Xinlin WANG
    J. Mater. Sci. Technol., 2005, 21 (02): 211-214. 
    Abstract   HTML   PDF (494KB)
    A magnetic shape memory alloy with nonstoichiometric Ni50Mn27Ga23 was prepared by using melt-spinning technology. The martensitic transformation and the magnetic-field-induced strain (MFIS) of the polycrystalline melt-spun ribbon were investigated. The experimental results showed that the melt-spun ribbons underwent thermal-elastic martensitic transformation and reverse transformation in cooling and heating process and exhibited typical thermo-elastic shape memory effect. However the start temperature for martensitic transformation decreased from 286 K for as-cast alloy to 254 K for as-quenched ribbon and Curie temperature remains approximately constant. A particular internal stress induced by melt-spinning resulted in the formation of a texture structure in the ribbons, which made the ribbons obtain larger martensitic transformation strain and MFIS. The internal stress was released substantially after annealing, which resulted in a decrease of MFIS of the ribbons.
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    Effect of Cu on Discontinuous Precipitation of a Symmetrical AlZn Alloy
    Shiming HAO, Yuping REN, Dapeng WANG, Danyang DONG, Hongxiao LI
    J. Mater. Sci. Technol., 2005, 21 (02): 215-218. 
    Abstract   HTML   PDF (1362KB)
    The effect of Cu additions on discontinuous precipitation of AlZn alloy were studied with optical microscopy, scanning electron microscopy and X-ray diffraction. It is found that the effect of addition of 2 at. pct Cu on cellular nucleation site is not remarkable, while the effect of aging temperature on cellular nucleation site of AlZn and AlZn-2Cu alloys is fairly obvious. The cell growth rate of discontinuous precipitation of AlZn alloy is remarkably accelerated with the addition of 2 at. pct Cu. The discontinuous precipitation microstructure of AlZn alloy is not apparently affected with the addition of 2 at. pct Cu and the cellular front is still fine microstructure of spinodal decomposition. The phase constituents consist of a fcc Al-rich phase, a hcp Zn-rich phase and a CuZn4 phase. The transformation rate of discontinuous precipitation of AlZn alloy is remarkably accelerated with the addition of 2 at. pct Cu.
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    Grain Size Control of Semisolid A356 Alloy Manufactured by Electromagnetic Stirring
    Z.Yang, P.K.Seo, C.G.Kang
    J. Mater. Sci. Technol., 2005, 21 (02): 219-225. 
    Abstract   HTML   PDF (696KB)
    To investigate the possibility of substituting the mechanical stirring system with electromagnetic stirring (EMS) system for aluminum rheo die-casting, the EMS under the different stirring cooling conditions was carried out. It was found that in the early period of solidification, the dendrite breakages led to a fine primary phase. When dendrites grew coarsely, the effect of ripening on grain size overwhelmed that of dendrite breakage. It was also found that the high cooling rate favored large nucleation rate, and led to a fine primary phase. But high cooling rate also made the growth rate of the dendrite arm, which prevented the dendrite arm from being sheared off. Therefore there were a suitable stirring time and suitable cooling rate to obtain the best rheo die-casting structure. Qualified semisolid A356 aluminum alloy was successfully manufactured with short time EMS.
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    Pitting Corrosion of Cu-Zn-Al Shape Memory Alloy in Simulated Uterine Fluid
    Bangyi CHEN, Chenghao LIANG, Daojun FU
    J. Mater. Sci. Technol., 2005, 21 (02): 226-230. 
    Abstract   HTML   PDF (276KB)
    Electrochemical test technology and surface analysis method were employed to investigate the pitting corrosion of Cu-Zn-Al shape memory alloy in simulated uterine fluid. The results showed that the breakage of the breaking-renovating equilibrium of surface layers resulted in the pitting corrosion of Cu-Zn-Al shape memory alloy in simulated uterine fluid. The development of pitting corrosion was controlled by dissolution of surface layers. The critical pitting corrosion potential was 1.70 VSCE. The kinetics equation for the development of pitting corrosion for Cu-Zn-Al shape memory alloy in simulated uterine fluid was i0=465.68 t-0.5+1.5. Pitting appearances of pits could be two types: tortoise-shell, and anomaly abscess. Cl- ion facilitated the pitting corrosion of Cu-Zn-Al shape memory alloy by competing adsorption and concentrating on alloy surface at high positive potential.
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    Geometric Effects of La1+xMg2-xNi9 (x=0.02~1.0) Ternary Alloys on Their Hydrogen Storage Capacities
    Zhiqing YUAN, Guanglie LU, Bin LIAO, Yongquan LEI
    J. Mater. Sci. Technol., 2005, 21 (02): 231-233. 
    Abstract   HTML   PDF (214KB)
    Structural analysis was made using X-ray diffraction (XRD) Rietveld refinement on a series of La1+xMg2-xNi9 (x=0.02~1.0) ternary alloys. Results showed that each of La1+xMg2-xNi9 alloys was a PuNi3-type structure stacked by LaNi5 and (La, Mg) Ni2 blocks. Electrochemical tests revealed that discharge abilities of these La-Mg-Ni ternary alloys mainly depended on their atomic distances between (La, Mg) and Ni, which could be modified by varying the atomic ratios of La/Mg.
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    Long-period Gratings in-situ Sensing for Flow Monitoring in Liquid Composite Molding
    Yingdan ZHU, Chang WANG, Jihui WANG, Wei HE, Guoqiang GAO
    J. Mater. Sci. Technol., 2005, 21 (02): 234-238. 
    Abstract   HTML   PDF (687KB)
    Liquid composite moulding (LCM) processes are used to manufacture high quality and complex-shaped composite parts in the automotive, marine, aerospace and civil industries. On-line sensing plays an important role in controlling the quality of the final product in the LCM manufacturing environment. The long-period fiber grating (LPG) technology, a new real-time fiber optic sensor system, was developed to monitor the flow front progression. The sensor operation and characterization under various process conditions were discussed in detail. The experimental results showed that LPG sensors were robust and reliable to detect the arrival of resin at pre-selected locations in structures with low-medium fiber volume fraction; however were limited at different depths in structures with high fiber volume fraction.
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    Chloroform Aided Extraction Spectrophotometric Determination of Rhenium Using Thiocyanate Complexing Agent
    E.Keshavarz Alamdari, S.K.Sadrnezhaad, Z.Mos-hefi Shabestari
    J. Mater. Sci. Technol., 2005, 21 (02): 239-242. 
    Abstract   HTML   PDF (335KB)
    A new technique is developed for quantitative determination of rhenium in aqueous media containing molybdenum, iron and copper ions. The method seems easier and more accurate than the traditional ones. It consists of the formation of rhenium thiocyanate complex, which is extracted with chloroform at the presence of hydrochloric acid. This complex is a highly visible light absorbent that can easily be detected with the aid of a spectrophotometer. The maximum absorbance (λmax) observed for this complex was in the visible range of 430~435 nm. The experimental results showed that in a concentration range from 0.5~8 mg/L, the absorbance behavior of the rhenium thiocyanate complex is followed to the Beer-Lambert law.
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    Corrosion by a Heavy Metal Oxide Glass
    J. Mater. Sci. Technol., 2005, 21 (02): 243-245. 
    Abstract   HTML   PDF (242KB)
    Melts of lead bismuth gallate compositions are highly corrosive and attack on crucibles of different materials. In the present study, corrosion by a base glass (50PbO-30Bi2O3-20Ga2O3 in mole fraction) melted using different crucibles and the effect on UV-VIS and IR edges were studied. By melting the base glass in platinum/2% rhodium, gold zirconia and alumina crucibles showed less effect on the IR edge and therefore shifted the infrared edge to longer wavelength, whereas silica crucible contaminated the glass, causing a severe deterioration in the infrared and hence shifted infrared edge to much shorter wavelength. In the UV-VIS region, base glass melted in platinum/2% rhodium crucible shifted the edge to the longest wavelength whereas silica crucible shifted the edge to shorter wavelength. The contaminants from gold, zirconia and alumina crucibles caused the UV-VIS edge of the base glass to lie between the two extremes of Pt/2% Rh and SiO2 crucibles. The glasses melted in above mentioned crucibles were also characterized with inductively coupled plasma spectroscopy (ICP) analysis to measure the level of contamination from the crucibles. Depending upon crucible used, the colors of glasses obtained ranged from red to yellow.
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    Fretting Fatigue Improvement of Ti6Al4V by Coating and Shot Peening
    Daoxin LIU, Xiaodong ZHU, Bin TANG, Jiawen HE
    J. Mater. Sci. Technol., 2005, 21 (02): 246-250. 
    Abstract   HTML   PDF (488KB)
    Ion beam enhanced deposition (IBED) was employed to increase the fretting fatigue resistance of Ti6Al4V. CrN and TiN hard coatings were applied on the base material and shot peening was combined with the hard coatings to study the duplex effect on fretting fatigue resistance. The IBED coatings exhibited a good bonding strength. They did not spall off even after shot peening. However, an optimum composition of CrN showed better fretting fatigue resistance than that of TiN with the same processing parameters.
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    Microstructure and Properties of Low Temperature Composite Chromized Layer on H13 Tool Steel
    Cuilan WU, Chengping LUO, Ganfeng ZOU
    J. Mater. Sci. Technol., 2005, 21 (02): 251-255. 
    Abstract   HTML   PDF (559KB)
    Low temperature composite chromizing is a process composed of a plain ion-carbonitriding or ion-nitriding at 550~580℃, followed by a low-temperature chromizing in a salt-bath of 590℃. The microstructure and properties of the low temperature composite chromized layer on H13 tool steel were investigated using metallography, X-ray diffraction, microanalysis, hardness and wear tests. It was found that this low temperature process was thermodynamically and kinetically possible, and the composite chromized layer on H13 steel, with a thickness of 3~6 μm, consisted of three sub-layers (bands), viz. the outer Cr-rich one, the intermediate (black) one, and the inner, original white layer. After chromizing, the former diffusion layer was thickened. The results of X-ray diffraction showed that the composite chromized layer contained such nitrides and carbides of chromium as CrN, Cr2N, (Cr, Fe)23C6, and (Cr, Fe)7C3, as well as plain α-(Fe, Cr). A high surface microhardness of 1450~1550 HV0.025, which is much higher than that obtained by the conventional ion carbonitriding and ion nitriding, was obtained. In addition, an excellent wear resistance was gained on the composite chromized layer.
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    Effect of δ Phase on Hydrogen Embrittlement of Inconel 718 by Notch Tensile Tests
    Liufa LIU, Chen LU, Wenjiang DING, Akio Hirose, Kojiro F.Kobayashi
    J. Mater. Sci. Technol., 2005, 21 (02): 256-260. 
    Abstract   HTML   PDF (452KB)
    The effect of δ phase on the hydrogen embrittlement (HE) sensitivity of Inconel 718 was investigated by conducting notch tensile tests. Notch tensile specimens with various precipitation morphologies of δ phase were prepared with different heat treatments, and hydrogen was charged into the tensile specimens before tensile tests via a cathodic charging process. The loss of notch tensile strength (NTS) due to the charged hydrogen was used to evaluate the hydrogen embrittlement sensitivity. The results show that δ phase has deleterious effect on NTSs, and the fracture of hydrogen-charged specimens initiated near the notch surfaces. The loss of NTS caused by precharged hydrogen can be greatly decreased by dissolving δ phase. δ-free Inconel 718 alloy is proposed for the applications in hydrogen environments.
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    Effects of Blending Routes on the Morphology and Properties of PA-6/Nano-CaCO3/MA-POE Ternary Composites
    Na FENG, Rui HUANG, Shengling JIANG, Junlong LIU, Chun MA
    J. Mater. Sci. Technol., 2005, 21 (02): 261-264. 
    Abstract   HTML   PDF (423KB)
    The effect of blending routes on the morphology and properties of Polyamide-6 (PA-6)/nano-CaCO3/Maleated ethylene-octane copolymer (MA-POE) ternary composite was analyzed using static mechanical test (DMA), TEM (transmission electronic microscope) and SEM (scanning electron microscope). It was found that MA-POE, as an impact modifier, had a profound effect upon the toughness of the PA-6/nano-CaCO3 composite. In particular, by adopting two-stage blending route, the microstructure of the ternary composites turned to core-shell structure, and the impact toughness was improved greatly. At the same time, tensile strength and dynamic storage modulus (E') were higher than those with one-stage blending route processed ternary composite. The results suggest that blending routes may improve the properties of PA-6/nano-CaCO3/MA-POE ternary composites.
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    Semi-solid Pressing Bonding Strength between Steel and Cu-graphite Composite
    Peng ZHANG, Yunhui DU, Hanwu LIU, Daben ZENG, Jianzhong CUI, Limin BA
    J. Mater. Sci. Technol., 2005, 21 (02): 265-268. 
    Abstract   HTML   PDF (255KB)
    The pressing bonding of steel plate with QTi3.5-3.5graphite slurry was studied. The relationship among preheating temperature of steel plate, preheating temperature of dies, solid fraction of QTi3.5-3.5graphite slurry, and interfacial shear strength of bonding plate could be established with artificial neural networks perfectly. This model could be optimized with a genetic algorithm. The results show that the optimum bonding parameters are: 618℃ for preheating temperature of steel plate, 526℃ for preheating temperature of dies and 46.2% for solid fraction of QTi3.5-3.5graphite slurry, and the largest interfacial shear strength of bonding plate is 128.3 MPa.
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    Ablation Performance of a Novel Super-hybrid Composite
    Jun QIU, Xiaoming CAO, Chong TIAN, Jinsong ZHANG
    J. Mater. Sci. Technol., 2005, 21 (02): 269-273. 
    Abstract   HTML   PDF (525KB)
    A novel super-hybrid composite (NSHC) was boron-modified phenolic resin (BPR) with three-dimensional reticulated SiC ceramic (3DRC) and high silica fibers. Ablation performance of the NSHC was studied. The results show that the linear ablation rate of NSHC was lower than that of pure BPR and the high silica/BPR composite. Its linear ablation rate is 1/17 of the high silica/BPR. Mass ablation rate of the NSHC is very close to that of the pure BPR and the high silica/BPR composite. Scanning electron microscope (SEM) analysis indicates that 3DRC has scarcely changed its shape at the ablation temperature. Its special reticulated structure can restrict the materials deformation and prevent high velocity heat flow from eroding the surface of the materials largely and thus increase ablation resistance of the NSHC.
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    Optimal Dearsenification Parameters of Gold Sulfide Concentrate with a High As Content
    Yaozhong LAN, Rose W.Smith
    J. Mater. Sci. Technol., 2005, 21 (02): 274-276. 
    Abstract   HTML   PDF (246KB)
    The gold sulfide concentrate with a high As content in Liangshan District, Sichuan Province, China, is a potentially important resource. This paper describes experiments of dearsenification of gold concentrate in a weakly reduced atmosphere in a rotary pipe furnace. The results showed that the optimal parameters were a temperature range of 650~700℃, 15%~16% CO2 of gas and a reaction time of 30~40 min. The removal rate of arsenic and sulfur was over 95% and 25%~28%, respectively. With further oxidization and roasting, residue sulfur in the roasted materials was dropped to below 4%, and the cyanide leaching recovery of gold was over 92%.
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    Precise Determination of the MgAlON/(AlN+MgAlON) Phase Boundries in the MgO-AlN-Al2O3 Ternary System at 1600℃ and 1700℃
    Houxing ZHANG, Yanruo HONG, Yong HUANG, Jialin SUN
    J. Mater. Sci. Technol., 2005, 21 (02): 277-280. 
    Abstract   HTML   PDF (393KB)
    The accurate phase boundary of MgAlON/(AlN+MgAlON) in MgO-AlN-Al2O3 ternary system, has not been determined precisely so far. In the present study, the lattice parameters of MgAlON solid solution with various compositions were determined precisely with X-ray powder diffraction. According to the relationship between the lattice parameters of MgAlON solid solution and the contents of AlN and MgO, the phase boundaries of MgAlON/(AlN+MgAlON) in MgO-AlN-Al2O3 ternary system at 1600℃ and 1700℃ were precisely determined.
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    Effect of the Oxidation Time on Properties of Ceramic Coatings Produced on Ti-6Al-4V by Micro-Arc Oxidation
    Zhaohua JIANG, Xuetong SUN, Yanping LI, Fuping WANG, Y, ong LÜ
    J. Mater. Sci. Technol., 2005, 21 (02): 281-284. 
    Abstract   HTML   PDF (446KB)
    Ceramic coatings were prepared on Ti-6Al-4V alloy using ac micro-arc oxidation (MAO) in silicate-hypophosphate solution. Growth regularity and formation mechanism of ceramic coatings were discussed. It was found that during the first stage the growth rate of coatings toward the external surface was larger than that toward substrate and then the coating began to grow mainly towards Ti alloy. When the total coating thickness reaches a certain value, it would no longer increase. In addition, the variations of the composition and microstructure of ceramic coatings according to the depositing time were also investigated with X-ray diffraction (XRD) and scanning electron microscope (SEM). The amount of rutile TiO2 gradually increased, whereas the amounts of the anatase TiO2 and amorphous phases first increased and then decreased slightly.
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    Structure and Characteristics of Oxide Films Containing Ca and P on Ti Substrate
    Fu LIU, Fuping WANG, Tadao Shimizu, Kaoru Igarashi, Liancheng ZHAO
    J. Mater. Sci. Technol., 2005, 21 (02): 285-288. 
    Abstract   HTML   PDF (442KB)
    The ceramic coating was formed by using microarc oxidation (MAO) in the electrolytic solution of β-Glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The microstructure, phase structure and phase composition were investigated with scanning electron microscopy (SEM), atomic force microscope (AFM), energy dispersive X-ray microanalyser (EDX), X-ray photoelectron spectroscopy (XPS), electron probe micro analyzer (EPMA) and X-ray diffraction (XRD). Investigation of the chemical composition of the coating with EDX revealed that Ca and P of high concentration existed in oxide films. XRD patterns indicated that the oxide film was composed of only anatase at low voltage discharge, and that rutile peaks appear in addition to anatase peak with increasing MAO voltage. Despite the existence of Ca and P, compounds concerning Ca and P were not detected in the oxide film.
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ISSN: 1005-0302
CN: 21-1315/TG
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