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 July 2004, Volume 20 Issue 04 Previous Issue    Next Issue
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    Research Articles
    New Evaluation on the Preoxidation Extent of Different PAN Precursors
    Wangxi ZHANG, Jie LIU, Jieying LIANG
    J. Mater. Sci. Technol., 2004, 20 (04): 369-. 
    Abstract   HTML   PDF (677KB)
    Structural changes in carbon fibers at each stage of, especially, preoxidation process are well known to play a great role in achieving the ultimate product quality. Differential scanning calorimetry (DSC), scanning electron microscope (SEM), density method and optical microscope were used to characterize the preoxidation extent. A conventional approach, e:g., density aim, to evaluate the extent of preoxidation is not very exact. A DSC curve of a PAN precursor only can provide general information, major in the temperature regime of preoxidation reaction. However, the evaluation of a preoxidation extent, especially from conventional preoxidation temperature with a great span regime of 200~400℃, is put forward in this paper, in which the evolution of core/shell morphological structure is a kind of straightforward evidence.
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    Optimizing the Machining Parameters for Minimum Surface Roughness in Turning of GFRP Composites Using Design of Experiments
    K.Palanikumar, L.Karunamoorthy, R.Karthikeyan
    J. Mater. Sci. Technol., 2004, 20 (04): 373-378. 
    Abstract   HTML   PDF (1206KB)
    In recent years, glass fiber reinforced plastics (GFRP) are being extensively used in variety of engineering applications in many different fields such as aerospace, oil, gas and process industries. However, the users of FRP are facing difficulties to machine it, because of fiber delamination, fiber pull out, short tool life, matrix debonding, burning and formation of powder like chips. The present investigation focuses on the optimization of machining parameters for surface roughness of glass fiber reinforced plastics (GFRP) using design of experiments (DoE). The machining parameters considered were speed, feed, depth of cut and workpiece (fiber orientation). An attempt was made to analyse the influence of factors and their interactions during machining. The results of the present study gives the optimal combination of machining parameters and this will help to improve the machining requirements of GFRP composites.
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    Elasto-Plastic FEM Analysis of Residual Stress in Spun Tube
    Fuan HUA, Yuansheng YANG, Dayong GUO, Wenhui TONG, Zhuangqi HU
    J. Mater. Sci. Technol., 2004, 20 (04): 379-382. 
    Abstract   HTML   PDF (546KB)
    The residual stress distribution of Hastelloy C corrosion-resistant alloy tubes after power spinning was simulated with the elasto-plastic finite element method combining with the element birth and death technique, the influences of spinning parameters on the distribution of the residual stress were investigated in detail, and the formation mechanism of residual stress during tube spinning was discussed. Based on the calculation of the residual stress, the reasons for annealing cracks on the spun tube during interpass heat treatment were explored. The simulation results and the characteristics of annealing cracks show that the circumferential residual tensile stress is a main factor to cause the annealing cracks.
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    Microstructural Evolution on the T91 Dissimilar Metal Joints during Creep Rupture Tests
    Guangmin LUO, Jiansheng WU, Qingsen MENG
    J. Mater. Sci. Technol., 2004, 20 (04): 383-386. 
    Abstract   HTML   PDF (909KB)
    T91 steel is one of the new materials presently employed in power plant pipe components. The creep rupture strength and microstructure of the T91+10CrMo910 and T91+13CrMo44 welded joints were analyzed during creep rupture tests. Creep transgranular ductile rupture occurred at the 10CrMo910 matrix in the T91+10CrMo910 welded joints and creep intergranular brittle rupture occurred at the 13CrMo44 HAZ in the T91+13CrMo44 joints. Microhardness measurements showed high hardness at the heat affected zone (HAZ) of T91 and a sharply drop at the 13CrMo44 HAZ during creep rupture. The metallographic tests showed that no obvious microstructure degradation was observed in the 10CrMo910 HAZ and matrix, while creep cracks appeared at the 13CrMo44 HAZ. T91 steel had relatively high creep resistant strength in the welded joints tested. Recovery occurred in the T91 HAZ with the growth of subgrain size and the decrease of dislocation density during creep. It was concluded that the dissimilar joints of T91 and low alloy heat-resistant steel should have close creep strength matching to increase the service life of the overall joints at elevated temperature.
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    Finite Element Analysis of Modeling Residual Stress Distribution in All-position Duplex Stainless Steel Welded Pipe
    Xiaojun JIN, Lixing HUO, Yufeng ZHANG, Bingren BAI, Xiaowei LI, Jun CAO
    J. Mater. Sci. Technol., 2004, 20 (04): 387-390. 
    Abstract   HTML   PDF (1082KB)
    On the basis of the thermal-elastic-plastic theory, a three-dimensional finite element numerical simulation is performed on the girth welded residual stresses of the duplex stainless steel pipe with ANSYS nonlinear finite element program for the first time. Three-dimensional FEM using mobile heat source for analysis transient temperature field and welding stress field in circumferential joint of pipes is founded. Distributions of axial and hoop residual stresses of the joint are investigated. The axial and the hoop residual stresses at the weld and weld vicinity on inner surface of pipes are tensile, and they are gradually transferred into compressive with the increase of the departure from the weld. The axial residual stresses at the weld and weld vicinity on outer surface of pipes is compressive while the hoop one is tensile. The distributions of residual stresses compared positive-circle with negative-circle show distinct symmetry. These results provide theoretical knowledge for the optimization of process and the control of welding residual stresses.
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    Separation of the Martensite in TiNi Fiber Reinforced Aluminum Matrix Composite
    Yanjun ZHENG, Lishan CU, IYan LI, Dazhi YANG
    J. Mater. Sci. Technol., 2004, 20 (04): 390-394. 
    Abstract   HTML   PDF (815KB)
    The reverse martensitic transformation of TiNi shape memory alloy fibers embedded in a pure aluminum matrix was studied in this paper. Results showed that the phase composition of the TiNi alloy fibers prior to prestraining at the room temperature had a significant influence on the differential scanning calorimetry (DSC) results of the composites. By a comparison to the high temperature X-ray diffraction (XRD) results, it was confirmed that the martensite was divided into two groups: the self-accommodating martensite (SAM) and the preferentially oriented martensite (POM). The evolving process of the separation of martensite was discussed.
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    Sliding Wear Behavior of Plasma Sprayed Alumina-Based Composite Coatings against Al2O3 Ball
    Minh-quy Le, Young-hun Chae, Seock-sam Kim
    J. Mater. Sci. Technol., 2004, 20 (04): 395-401. 
    Abstract   HTML   PDF (3657KB)
    The sliding wear behaviors of a single layer Al2O3-30 wt pct ZrO2, a double layer Al2O3-30 wt pct ZrO2/Ni-Cr and a single layer Al2O3-13 wt pct TiO2 coating deposited on low carbon steel by plasma spraying were investigated under lubricated conditions with various normal loads. The plastic deformation, detachment and pull out of splats were involved in the wear process of the studied coatings under test conditions. Crack propagation was found in Al2O3-13 wt pct TiO2 under loads of 70 and 100 N and in Al2O3-30 wt pct ZrO2/Ni-Cr under a load of 130 N. While increasing the normal load, the wear rates of Al2O3-30 wt pct ZrO2 and Al2O3-30 wt pct ZrO2/Ni-Cr slightly increased, the wear rate of Al2O3-13 wt pct TiO2 increased rapidly. The results showed that the Ni-Cr bonding layer improved the wear resistance of the coating system even it is relatively thin compared with the outer coating layer. The influence of this bonding layer on wear behavior of the coating increased as increasing the normal load.
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    Microstructure Characteristics of Interaction Layer of Zn-Al Eutectic Alloy with Al2O3p/6061Al Composites
    Jiuchun YAN, Zhiwu XU, Shixiong LÜ, Shiqin YANG
    J. Mater. Sci. Technol., 2004, 20 (04): 401-404. 
    Abstract   HTML   PDF (1414KB)
    The interaction between Zn-Al eutectic alloy and Al2O3p/6061Al composites in the vacuum furnace was investigated. Great attention has been paid. to the elements diffusion, the microstructure and formation of the interface between Zn-Al eutectic alloy and Al2O3p/6061Al composites. Experimental results show that Zn-Al eutectic alloy has a good wetting ability to Al2O3p/6061Al composites and the wetting angle decreases with increasing the temperature in vacuum. After the interaction, an interaction layer forms between Zn-Al alloy and Al2O3p/6061Al composites. The phases in the interaction layer mainly consist of α-Al(Zn), Al2O3 and CuZn5 resulted from the diffusion of elements from the Zn-Al alloy. Several porosities distribute in the region near the interface of the Zn-Al alloy/interaction layer. The amount of shrinkage voids in the interacting layer is relevant to the penetration of Zn element into Al2O3p/6061Al composites which is a function of temperature. So it is necessary to lower heating temperature in order to limit the Zn penetration.
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    Density of Ni-Al Alloys in Liquid and Solid-Liquid Coexistence State Measured by a Modified Pycnometric Method
    Liang FANG, Feng XIAO, Zushu LI, Zainan TAO
    J. Mater. Sci. Technol., 2004, 20 (04): 405-410. 
    Abstract   HTML   PDF (787KB)
    The density of Ni-Al alloys in both liquid state and solid-liquid coexistence state was measured with a modified pycnometric method. It was found that the density of Ni-Al alloys decreases with increasing temperature and Al concentration in the alloys. The molar volume of liquid Ni-Al binary alloys increases with the increase of temperature and Al concentration. The partial molar volume of Al in Ni-Al binary alloy was calculated approximately. The molar volume of liquid Ni-Al alloy determined in the present work shows a negative deviation from the ideal linear molar volume.
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    Density and Structure Analysis of Molten Ni-W Alloys
    Feng XIAO, Liang FANG
    J. Mater. Sci. Technol., 2004, 20 (04): 410-413. 
    Abstract   HTML   PDF (447KB)
    Density of molten Ni and Ni-W alloys was measured in the temperature range of 1773~1873 K with a sessile drop method. The density of molten Ni and Ni-W alloys trends to decrease with increasing temperature. The density and molar volume of the alloys trend to increase with increasing W concentration in the alloys. The calculation result shows an ideal mixing of Ni-W alloys.
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    Improvement of Hydrogen Storage Properties of La0.6M0.4Ni4.8Mn0.2 Alloys
    Ping DU, Wei CAO, Manqi LÜ, Jiangping CHEN, Ke YANG
    J. Mater. Sci. Technol., 2004, 20 (04): 414-416. 
    Abstract   HTML   PDF (553KB)
    Investigation has been carried out to find the effects of Nd substitution and Cu addition on the hydrogen storage properties of AB5-type alloy with a multicomponent La0.6M0.4Ni4.8Mn0.2 (M=Y, Nd) system. La0.6M0.4Ni4.8Mn0.2, which was used in an air-conditioning system, showed poor hysteresis and sloping characteristics, which led to a decrease concerning the coefficient of performance of the system. By the substitution of Nd for Y, the hydrogen storage capacity increased, and the plateau pressure decreased a little, but the hydrogen absorption kinetics decreased dramatically. Cu addition can effectively improve the kinetics of hydride formation without changing the hydrogen storage capacity of La0.6M0.4Ni4.8Mn0.2. It has been found that La0.6Nd0.4Ni4.8Mn0.2Cu0.1 alloy showed good hydrogen storage characteristics for metal hydride air-conditioning system. The results showed that, for each component of La0.6M0.4Ni4.8Mn0.2, the effective hydrogen storage capacity increased with decrease of the unit cell parameter c/a and the hydrogen absorption plateau pressure increased with decrease of the parameter a.
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    Structural and Magnetic Analyses of Magnetic Nanoparticles Coated with Oleate Molecules
    Kailun YAO, Jin TAO, Zuli LIU, Qianghua LU, Dong XI, Xiaoping LUO, Qin NING
    J. Mater. Sci. Technol., 2004, 20 (04): 417-420. 
    Abstract   HTML   PDF (554KB)
    Physical and chemical properties of the magnetic nanoparticles coated with oleate have been investigated by means of transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Mo¨ssbauer spectroscopy, superconducting quantum interference device (SQUID) magnetometry, infrared spectra (IR) and the contact angle device. The results show that doped Al ions in Fe3O4 nanoparticles are located on the octahedral sites of the spinel structure. Oleate is coated on the magnetic nanoparticles with two layers by chemical absorbing, the outer layer can be washed away. The wetting of the surface of magnetic nanoparticles coated with monolayer has been changed from hydrophilicity to hydrophobicity, and the nanoparticles can be dispersed very well in some organic solutions.
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    Study Segregation of Alloying Elements in Continuous Casting Slab with Valence Electron Structure
    Yan LIU, Zhilin LIU, Chengwei ZHANG, Yingguang ZHU
    J. Mater. Sci. Technol., 2004, 20 (04): 421-425. 
    Abstract   HTML   PDF (367KB)
    By calculating the electron structures of the phases that phosphor, sulfur and alloying elements dissolving in γ-Fe, the reason why alloying elements can bring centerline segregation in continuous casting slab (CCS) with nA, the number of electrons on the strongest covalent bonds, and the structure formation factor S were investigated, and an electron structural criterion to control and to eliminate the centerline segregation was advanced. Basing on this, the electron structures of a part of rare earth phosphides and sulfides are calculated, the physical mechanism that rare earth elements can control the segregation of phosphor and sulfur is analyzed, and the criterion is well verified.
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    HRTEM Study on Precipitates in High Co-Ni Steel
    Zhengfei HU, Xingfang WU, Chunxu WANG
    J. Mater. Sci. Technol., 2004, 20 (04): 425-428. 
    Abstract   HTML   PDF (972KB)
    The secondary hardening reaction is accompanied with precipitation of fine carbides in high CoNi ultrahigh strength steel. The crystal structure of the precipitating carbides is unambiguously determined by microbeam diffraction in transmission electron microscopy. It is identified that the needle-shaped carbides are M2C with a hexagonal structure. The concentration of substitutional alloying elements in the carbides quantified by energy dispersive X-ray spectroscopy (EDS) also supports the result above. The spatial structure of M2C is identical with 3 type. Metal atoms are in a close packed hexagonal structure, the carbon atoms partly distribute with random in the octahedral interstices and the filling probability is less than 1/2. Particular attention was paid to the relationship of needleshaped carbides/ferrite matrix at secondary hardening peak tempered at 482℃ for 5 h. Observation by high resolution transmission electron microscopy (HRTEM) confirms that carbides with black-white contrast are fully coherent with ferrite and have individual crystal structure, and the coarsened carbides with moir fringe are partially coherent with matrix. The orientation relationship between M2C and ferrite matrix is directly observed and identified with the well established P-S relationship [001]α //[ ]c.
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    Ab Initio Calculations of the Electronic Structures of Copper Pyrites CuS2, CuSe2 and CuTe2
    Zhufeng HOU, Aiyu LI, Zizhong ZHU, Meichun HUANG
    J. Mater. Sci. Technol., 2004, 20 (04): 429-431. 
    Abstract   HTML   PDF (296KB)
    The electronic structures of CuS2, CuSe2 and CuTe2 with pyrite structures, within the framework the density-functional theory have been investigated. The calculated results explained the recent experimental results which show that there is no clear indication of strong electron correlations in the electronic properties of Cu pyrites, due to the dominant chalcogen p character rather than d characteristic of Cu at the Fermi level.
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    Energy-storage Welding Connection Characteristics of Rapid Solidification AZ91D Mg Alloy Ribbons
    Jinfeng XU, Qiuya ZHAI, Sen YUAN
    J. Mater. Sci. Technol., 2004, 20 (04): 431-434. 
    Abstract   HTML   PDF (643KB)
    Energy-storage welding connection characteristics of rapidly solidified AZ91D Mg alloy ribbons with 40~70 μm thickness are investigated using a microtype energy-storage welding machine. The microstructure and performance of the connection joints are analyzed and studied. The research results indicate that energy-storage welding is able to realize the spot welding connection of AZ9ID Mg alloy ribbons. The welding nugget consists of developed α-Mg equiaxed grains with the sizes of 1.2~2.7 μm and intergranular distributed β-Mg17Al12 compounds. The thickness of bond zone is about 4 μm and the solidification microstructure is characterized by the fine equiaxed grains with the sizes of 0.8~1.2 μm, and grain boundary has become coarsening. The columnar crystal in HAZ also becomes slightly coarsening and the grain boundary has broadened, however, there is no obvious change in its primitive morphology and crystallographic direction. When welding energy is about 2.0 J, the welding joints with higher shear strength and smaller electrical resistivity are obtained.
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    Processing and Sintering of Agglomerate-free CaO-ZrO2 Powder
    Liping LIANG, Shue DANG, Dong WU, Yuhan SUN
    J. Mater. Sci. Technol., 2004, 20 (04): 435-438. 
    Abstract   HTML   PDF (500KB)
    Coprecipitation supercritical fluid drying technology has been employed to synthesize calcia-stabilized zirconia ultrafine powder with low-cost inorganic salts as the starting materials. The sintering behaviors of these powders were also investigated. The results showed that supercritical fluid drying could effectively alleviate the hard agglomeration of grains during the gel drying process, and the morphology of the powder retained the network texture of the original gel. The resulting particles were characterized by small particle size (5~20 nm), better monodispersity and high surface area, which gave rise to high activity and sinterability. Consequently, these powders could readily be compacted into the desired shape and their densification could be carried out in shorter time and at lower temperatures. For instance, nanometer-sized powder calcined at 600ºC for 2 h could be cold-pressed into a green body and sintered at 1100º for 0.5 h to attain a dense body with bulk density of 5.9718 g/cm3 and specific pore volume of 0.0008 cm3/g.
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    Morphology Controlling of the Ultrafine Cerium Dioxide (CeO2) Precursor
    Jianqing CHEN, Zhigang CHEN, Jinchun LI
    J. Mater. Sci. Technol., 2004, 20 (04): 438-440. 
    Abstract   HTML   PDF (389KB)
    The synthesis of ultrafine cerium dioxide precursor via homogeneous precipitation was studied. Mixed aqueous solution of anhydrous cerium nitrate and urea was first heated to 85℃ for 2 h, and the prepared suspension was then aged at room temperature for various periods of time. White precipitate was finally collected by centrifuging and washed with distilled water and anhydrous ethanol. The obtained cerium dioxide (CeO2) precursor was observed with SEM. It was found that the morphology and size of the precursor were strongly affected by aging time and stirring conditions (with or without stirring). The precipitated fine spherical particles of the precursor changed their shape from ellipse to slice or directly to slice. Fine spherical monodispersed (300 nm) precursor powders could be obtained by controlling the aging time. Stirring the solution also could change the reaction process and thus the morphology and size of the precursor are changed.
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    Preparation and Electromechanical Properties of PVDF Matrix Piezoelectric Composites Containing Highly Oriented BaTiO3 Whiskers
    Xuetao LUO, Lifu CHEN, Xiaojun CHEN, Qianjun HUANG
    J. Mater. Sci. Technol., 2004, 20 (04): 441-444. 
    Abstract   HTML   PDF (1583KB)
    The piezoelectric composites containing highly oriented BaTiO3 whiskers as active phase and PVDF as matrix have been prepared by micro-hole extrusion and orientation in carried fibers. The morphology of oriented BaTiO3 whiskers and microstructure of the composites were observed by SEM. As for its electromechanical properties, it is found that the dielectric constant, piezoelectric constant and remnant of polarization in the BaTiO3 whisker-PVDF composite are considerably higher than that in the BaTiO3 powders-PVDF composite, while the loss factors follow the opposite trend. For the BaTiO3 whisker-PVDF composite, the values of ε, d33 and Pr parallel to the whisker orientation (normal specimen) are much higher than that perpendicular to the whisker orientation (parallel specimen). The significant effects of the connective passages of active phase on electromechanical properties of the piezoelectric composites has also been investigated.
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    Performance of Potassium Titanate Whisker Reinforced PPESK Composites
    Minjie QU, Xigao JIAN, Wei HE, Gongxiong LIAO
    J. Mater. Sci. Technol., 2004, 20 (04): 445-447. 
    Abstract   HTML   PDF (790KB)
    A group of poly (phthalazinone ether sulfone ketone)/potassium-titanate-whisker (PPSEK/whisker) composites was prepared by coprecipitation from solution. The whisker surface was modified using titanate coupling agent prior to blending. The tensile, impact, morphology and thermal properties of the moulded composites were investigated. The measurements showed that the tensile strength and impact strength of the composites increased with increasing whiskers content up to 10 to 20 phr, thereafter they showed a decrease in the whiskers content reached 40 phr. At the same time, the modulus of the composites increased with increasing whiskers content. Scanning electron microscopy studies revealed that the whiskers within the composites were dispersed uniformly by treated with coupling agent. Finally, thermogravimetric analysis showed that the heat resistance of the composites tended to increase with increasing whisker content. The results were analysed and discussed in terms of established models of the behaviour of short-fiber reinforced composites.
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    Distribution of SiCp in Al and Al-Cu Alloy Centrifugally Cast with Electromagnetic Stirring
    Weiqiang ZHANG, Haifang SHI, Huameng FU
    J. Mater. Sci. Technol., 2004, 20 (04): 448-450. 
    Abstract   HTML   PDF (933KB)
    The SiCp/(Al-Cu) alloy and pure Al matrix composites have been prepared by the centrifugal casting with electromagnetic stirring. There are two particle-depleted zones formed in the samples without electromagnetic stirring. Electromagnetic stirring may result in a homogeneous distribution of fine SiC particles in the Al-Cu alloy, whereas it has little effect on the segregation in pure Al matrix. The results also show that the particle segregation is influenced by particle size and the coarse particles are more readily segregated than the fine ones.
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    On the Strength of Silicon Carbide Particulate Reinforced Aluminium Alloy Matrix Composites
    Mingjiu ZHAO, Yue LIU, Liqing CHEN, Jing BI
    J. Mater. Sci. Technol., 2004, 20 (04): 451-453. 
    Abstract   HTML   PDF (283KB)
    In the present study, the modified continuum model, quench strengthening and dislocation pile-up model was respectively used to estimate the yield strength of SiCp/Al composites. The experimental results showed that the modified shear lag model or quench strengthening model would underestimate the yield strength of SiCp/Al composites. However, the modified Hall-Petch correlation on the basis of the dislocation pile-up model, expressed as σcy = 244 + 371λ-1/2, fitted very well with the experimental data, which indicated that the strength increase of SiCp/Al composites might be due to the direct blocking of dislocation motion by the particulate-matrix interface. Namely, the dislocation pile-up is the most possible strengthening mechanism for SiCp/Al composites.
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    Model Building of Backup Roller Diameter Effect Rate in 4-High Mill
    Jianzhong XU, Dianyao GONG, Xianghua LIU, Guodong WANG, Xiaolin ZHAO
    J. Mater. Sci. Technol., 2004, 20 (04): 454-456. 
    Abstract   HTML   PDF (265KB)
    Software for calculating the strip profile in 4-high hot rolling mill was developed using influence coefficient method. Regularity of backup roller diameter effect rate was studied systematically using the software. The results show that backup roller diameter effect rates decrease versus the increase of strip width, increase significantly versus the increase of backup roller diameter and obscurely increase versus the increase of reduction. The difference between backup roller diameter effect rate and it is reference value increases versus strip width increasing. When backup rollers diameter is set to be 1.64 m and strip width is 1.85 m, the error of strip profile calculated using the model of backup roller diameter effect rate reference value will be 3.55 μm. Based on the results, reference values of roller diameter effect rate and six power polynomial fitting coefficients of modification coefficients were determined considering coherent parameters. The high precision model of backup roller diameter effect rate was established. When the model is used to predict strip profile, the accuracy is less than 5.0 μm.
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    Influence of Alternative Magnetic Field on the Diffusion of Al and Mg
    Xiaotao LIU, Jianzhong CUI, Yanhui GUO, Xiaoming WU, Jun ZHANG
    J. Mater. Sci. Technol., 2004, 20 (04): 457-459. 
    Abstract   HTML   PDF (499KB)
    The influence of an alternative magnetic field on the growth of the diffusion of Al and Mg in Al-Mg diffusion couple is studied. The diffusion zone is composed of two intermediate phases, namely β and γ phase. Thickness of each intermediate phase is examined. The results show that the alternative magnetic field increase the thicknesses of β and γ phase zone and the layer growth of β and γ phase obeys the parabolic rate law. The growth rate of the β and γ phase are increased with the application of the alternative magnetic field. This change is manifested through a change in the frequency factor k0 and not through a change in the activation energy Q. The frequency factor k0 for intermediate phase growth with an alternative magnetic field is 39.95 cm2/s for γ phase and 2.84×10-4 cm2/s for β phase compared with those without the magnetic field is 22.4 cm2/s for γ phase and 1.53×10-4 cm2/s for β phase.
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    Synthesis and Magnetic Properties of Nanoparticles of Fe-Co Alloys and Their Oxides Prepared by Chemical Vapor Condensation
    Zhenhua WANG, Zhidong ZHANG, C.J.Choi, B.K.Kim, J.C.Kim
    J. Mater. Sci. Technol., 2004, 20 (04): 459-462. 
    Abstract   HTML   PDF (1269KB)
    Nanoparticles of Fe-Co alloys and their oxides with the particle size below 20 nm were prepared by chemical vapor condensation process. The pure Ar, Ar+1%O2, Ar+3%O2 and Ar+6%O2 were used as carrier gases, with iron carbonyl and cobalt carbonyl as the precursors. XRD patterns showed that Fe-Co metallic nanoparticles were synthesized by using pure Ar as carrier gas, and only metal oxides were obtained using Ar+(>3)%O2 as carrier gas. The HRTEM images and TG-DTA curves were used to study the core-shell structure of the different nanoparticles. The nanoparticles obtained in pure Ar consist of black core and light shell with thickness of 2~4 nm. However, in the particles obtained in Ar+6%O2, the oxides core with visible lattice fringes are surrounded by thin shell.
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    New Naturally Occurring Product Extract as Corrosion Inhibitor for 316 Stainless Steel in 5% HCl
    J. Mater. Sci. Technol., 2004, 20 (04): 463-466. 
    Abstract   HTML   PDF (442KB)
    Medipolymorphol, a new sterol isolated from the whole plant of Medicago polymorpha Roxb was used as corrosion inhibitor for 316 stainless steel in 5% HCl at room temperature. Electrochemical techniques have been found to be reliable in evaluating corrosion characteristics of the system. Several techniques have been used including Tafel, linear polarization, potentiodynamic polarization, and open circuit potential (OCP) studies. The additives simultaneously deaccelerated the anodic process, intensified the cathodic process and provided a stable passive state, giving good inhibition efficiencies to stainless steel electrodes. In addition, adsorption isotherm have been fitted for the inhibitor under investigation.
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    Prediction of Solid-Liquid Interface Stability by Coupling M-S Model with CALPHAD Method
    Ruijie ZHANG, Zhi HE, Zhongwei CHEN, Wanqi JIE
    J. Mater. Sci. Technol., 2004, 20 (04): 466-468. 
    Abstract   HTML   PDF (348KB)
    A method to predict the solid-liquid interface stability during unidirectional solidification is developed by coupling M-S model with CALPHAD method. The method was applied to Al-0.38 Zn and Al-0.34 Si-0.14 Mg (wt pct) alloys, and the predicted results were compared with some former experimental data of the two alloys. The good agreement between the calculation results and the experimental data demonstrates the superiority of the present method to the classical one based on constant parameter assumptions.
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    On the ζ-Potential of Nanodiamond in Aqueous Systems
    Yongwei ZHU, Xiangqian SHEN, Zhijing FENG, Xiangyang XU, Baichun WANG
    J. Mater. Sci. Technol., 2004, 20 (04): 469-471. 
    Abstract   HTML   PDF (559KB)
    Several factors affecting the ζ-potential of nanodiamonds were studied. The Chemical Mechanical Modification (CMM) of surface, different surfactants and its dosage, and inorganic ions on the ζ-potential of nanodiamond sample L were studied using ZETASIZER3000HS and Nexus470. Results show that the ζ-potential changes with its parameters of detonation synthesis and purification. Results also suggest that CMM and subsequent treatments employed can alter apparently the ζ-potential and that some anionic surfactants increase the absolute value of the ζ-potential in the alkaline surrounding.
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    Responding Depth of Photocatalytic Activity of TiO2 Self-assembled Films
    Weichang HAO, Feng PAN, Tianmin WANG, Shukai ZHENG
    J. Mater. Sci. Technol., 2004, 20 (04): 472-474. 
    Abstract   HTML   PDF (524KB)
    The electrostatically self-assembly method is getting strategically important to prepare multilayer thin films. With careful choice of component materials, this method should allow for the preparation of multilayer thin films with a variety of excellent technological properties. TiO2/PSS multilayer thin films with ordered structure were prepared by electrostatic self-assembly method. UV-Vis-NIR spectrophotometer, X-ray photoelectron spectroscopy (XPS), and atom force microscopy (AFM) were used to characterize the structure and performance of the multilayer films. Because electrostatically self-assembly method allows molecular-level control over the film composition and thickness, this paper studied the responding depth of photocatalytic activity of TiO2 self-assembled films in detail.
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    Surface Composition and Corrosion Property of TiNi Alloys Coated with Tantalum Films
    Yan CHENG, Wei CAI, Liancheng ZHAO
    J. Mater. Sci. Technol., 2004, 20 (04): 474-476. 
    Abstract   HTML   PDF (377KB)
    Multi-arc ion plating method was employed to coat TiNi alloys with Ta in order to improve radiopacity and corrosion resistance property. The surface composition, corrosion resistance property and Ni ions release amount of TiNi alloys coated with Ta films compared with TiNi alloys, are investigated by means of X-ray photoelectron spectrometry (XPS), electrochemical measurements and atomic absorption spectrophotometry (AAS), respectively. The results show that the coated surface composition is composed of Ta and O and the corrosion resistance is improved, whereas the Ni ions release amount of the coated sample is lower than that of the uncoated samples in the whole immersion period, indicating that Ta coating can improve the biocompatibility of TiNi alloys.
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    Incorporated Organic Modified Ag Nanoparticles in Ormocer
    Haiping XIA, Jianli ZHANG, Jinhao WANG, Qiuhua NIE
    J. Mater. Sci. Technol., 2004, 20 (04): 477-478. 
    Abstract   HTML   PDF (362KB)
    Ag nanoparticles coated trisodium citrate were incorporated in ormocer by sol-gel method. The doping concentration of Ag in ormocer is about 1.0% in weight. The HRTEM demonstrated that the particles disperse in ormocer, and the size of Ag nanoparticles is 5~10 nm. The absorption band of Ag nanoparticle at 410 nm was observed.
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    Deformation Behavior of Nanostructured Ceramic Coatings Deposited by Thermal Plasma Spray
    Xianliang JIANG, Eric Jordan, Leon Shaw, Maurice Gell
    J. Mater. Sci. Technol., 2004, 20 (04): 479-480. 
    Abstract   HTML   PDF (735KB)
    Al2O3-13 wt pct TiO2 coating deposited by direct current plasma spray consists of nanostructured region and microlamellae. Bend test shows that the ceramic coating can sustain some deformation without sudden failure. The deformation is achieved through the movement of nano-particles in the nanostructured region under tensile stress.
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ISSN: 1005-0302
CN: 21-1315/TG
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