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 November 2004, Volume 20 Issue 06 Previous Issue    Next Issue
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    Research Articles
    Effects of Additive AlCl3 on Crystal Phase, Particle Size and Microstructural Parameters of Nanocrystalline TiO2 Prepared by HF-PCVD
    Haiping XU, Yanping SUN, Xinmou CHEN
    J. Mater. Sci. Technol., 2004, 20 (06): 641-643. 
    Abstract   HTML   PDF (427KB)
    Nanocrystalline TiO2 was prepared by high frequency plasma chemical vapor deposition (HF-PCVD). The effects of additive AlCl3 on crystal phase, particle size and microstructural parameters of TiO2 nanocrystallites were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The nanocrystallites obtained experimentally are mixture of anatase and rutile, the uniform diameters of particles are about 30 nm. The phase transformation from anatase to rutile was accelerated by AlCl3, and rutile content is increased from 26.7 wt pct to 53.6 wt pct with increasing of addition of AlCl3 from 0.0 wt pct to 5.0 wt pct. The particle size is reduced and the size distribution becomes very narrow. The crystal lattice constants have the trend to decrease, and cell volumes appear as shrinkable.
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    Molecular Dynamics Study on Interfacial Energy and Atomic Structure of Ag/Ni and Cu/Ni Heterophase System
    Haijiang LIU, Shaoqing WANG, An DU, Caibei ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 644-648. 
    Abstract   HTML   PDF (672KB)
    The results of molecular dynamics calculations on the interfacial energies and atomic structures of Ag/Ni and Cu/Ni interfaces are presented. Calculation on Ag/Ni interfaces with low-index planes shows that those containing the (111) plane have the lowest energies, which is in agreement with the experiments. Comparing surface energy with interfacial energy, it is found the order of the interfacial energies of Ag/Ni and Cu/Ni containing the planes fall in the same order as solid-vapor surface energies of Ag, Cu and Ni. In this MD simulation, the relaxed atomic structure and dislocation network of (110) Ag||(110) Ni interface are coincident to HREM observations.
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    Complete Mill Simulation of the Rolling Process of 1660 mm Hot Strip Continuous Mills
    Yingrui WANG, Zhenshan CU, Yingjie WANG, Hongmin LIU
    J. Mater. Sci. Technol., 2004, 20 (06): 649-656. 
    Abstract   HTML   PDF (480KB)
    The three-dimensional plastic deformations of strip are analyzed using the stream surface strip element method, the elastic deformations of rolls are analyzed using the influence coefficient method, the analyzing and computing model of shape and crown of 4-high mill was established by combining them, and the rolling process of 1660 mm hot strip continuous mills was simulated. The simulated results tally well with the experimental results. The model and the method for simulation of shape analysis and control of hot strip mills were provided.
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    EPMA Study of the Interface of β-Tricalcium Phosphate Ceramics in Vivo
    Honglian DAI, Xianying CAO, Haichen SHAO, Chunhua SHEN, Shipu LI
    J. Mater. Sci. Technol., 2004, 20 (06): 657-661. 
    Abstract   HTML   PDF (649KB)
    Electron probe and X-ray energy spectrum were used to investigate the chemical composition of the interface between material and new bone after porous tricalcium phosphate ceramic implanted in tibia of rabbits. The element changes of the interface, the materials transformation and the situation of new bone formation at different implantation period were observed. The results showed that the carbon element content decreased gradually in new bone tissue, and the content of calcium and phosphor element increased by degrees with the implantation time. At the same time, calcium-phosphor ratio in the new bone kept a higher level. New bone grew into the materials interior, material dispersed and degraded simultaneously. Both composition of materials and new bone tended to be consentient. Finally, the materials were substituted by new bone. After implantation, not only the materials itself dissolved and degraded partially, but also new bone formed on the outer and pore surface of β-TCP porous bioceramics, which showed that the degradation products of lifeless calcium phosphate inorganic materials took part in constituting of new bone tissue.
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    Osteogenesis and Degradation Behavior of rhBMP-2/β-Tricalcium Phosphate Porous Composite Materials
    Weizhong YANG, Dali ZHOU, Ge LIANG, Guangfu YIN, Yun ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 661-664. 
    Abstract   HTML   PDF (359KB)
    Ultrafine β-tricalcium phosphate (β-TCP) powders with good crystalline structure were produced by a new wet process. Through bone tissue engineering approach, porous β-TCP ceramic was combined with recombined human bone morphogenetic proteins-2 (rhBMP-2) to develop a novel composite material. Osteogenesis capacity of the composite was investigated intramuscularly in rat with histological analyses and SEM examination. Pure β-TCP porous ceramic was investigated as the control. Results show that the composite materials possess good biocompatibility, biodegradation and strong osteogenesis capacity through inductive process after implantation. Material degradation began from 2 weeks post-implantation accompanying with the changing of pore structure, with the enwrapping and separation of materials by hyperplatic mesenchymal cells and fibroblast, and with the phagocytose reaction of multinucleated giant cells. Early in 72 h, immature cartilage could be found within novel composite; mature lamellar bone was induced to generate after 3 weeks. With strong osteoinduction capacity and controllable biodegradation, the novel rhBMP-2/β-TCP porous ceramic is expected to be a promising bone grafting substitute for bone tissue engineering.
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    Development of Biomimetic Needle-like Apatite Nanocrystals by a Simple New Method
    Jie WEI, Yubao LI, Yi ZUO, Xueling PENG, Li ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 665-667. 
    Abstract   HTML   PDF (343KB)
    A new method of calcium nitrate and sodium phosphate as reactants was employed to prepare biomimetic apatite nanocrystals by a simple heating treatment in water. The structure and properties of the apatite crystals were investigated by TEM, XRD, IR, ICP and TG. It is found that the apatite nanocrystals contain OH-, CO32-, Na+ and HPO42- ions in their crystal structure. The crystal water is removed during heating from 200℃ to 400℃. CO32- and HPO42- are decomposed at 600℃ to 800℃, also there is lattice water lost at this temperature stage. The morphology of the apatite nanocrystals is needle-like with a length less than 80 nm. The size and crystallinity of the apatite nanocrystals increase with water treatment temperature and time. Compared to the apatite crystals sintered at 800℃, water treated apatite nanocrystals are poorly crystallized apatite. The results indicate that the apatite nanocrystals have similarity in composition, structure, morphology and crystallinity to that of bone apatite crystals. It can be used to make apatite crystals/polymer biomimetic bone repair materials or for other biomedical applications.
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    1.3 μm Emission from Nd3+-doped Tellurite Glass Fiber
    Shixun DAI, Junjie ZHANG, Shunguang LI, Jianhu YANG, Shiqing XU, Guonian WANG, Lili HU
    J. Mater. Sci. Technol., 2004, 20 (06): 668-670. 
    Abstract   HTML   PDF (350KB)
    1 wt pct Nd2O3-doped tellurite bulk glass and fiber with the same composition of 75TeO2-15ZnO-5Na2O-5Li2O (mol fraction, %) were fabricated. Judd-Ofelt analysis was carried out for the bulk. The emission from the 4F3/2→4I13/2 transition in fiber is at 1.33μm wavelength with a spectral bandwidth of 55 nm, which is similar to that in bulk. In the case of the fiber, the lifetime of 4F3/2 level is 164μs, and the quantum efficiency is ~100%. The figure-of-merit for gain (σpτ0) for Nd3+-doped tellurite glass is about 2.8×10-24 cm2•s, which is quite comparable with that in Nd3+-doped fluoroaluminate glasses, and is an order of magnitude larger than Pr3+-doped fluoride glasses.
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    Preparation and ASE Spectrum of a Single-Mode Erbium Doped Tellurite Glass Fiber with D-type Cladding Geometry
    Junjie ZHANG, Shixun DAI, Guonian WANG, Shiqing XU, Shunguang LI, Lili HU
    J. Mater. Sci. Technol., 2004, 20 (06): 671-674. 
    Abstract   HTML   PDF (396KB)
    Based on the host of tellurite glasses, the glass formation, preform manufacture, and fiber fabrication are described. The characterization of amplified spontaneous emission (ASE) from this newly fabricated single-mode Er3+-doped tellurite fibers is also presented. When pumped at 980 nm, a very broad erbium ASE around 1.53 μm was observed. The variations of ASE with fiber length and pumping power are measured and discussed. The output of 2 mW from Er3+-doped tellurite fiber ASE source was obtained under the pump power of 660 mW.
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    Fabrication of Au/SiO2 Nanocomposite Films by Self-Assembly Multilayer Method
    Haihu YU, Honghui LI, Desheng JIANG, Xiaoyao CHEN, Enyu YANG
    J. Mater. Sci. Technol., 2004, 20 (06): 674-677. 
    Abstract   HTML   PDF (395KB)
    Gold colloid was prepared by chemical reduction of hydrogen tetrachloroaurate, polyelectrolyte/gold nanoparticle/silica nanoparticle composite films were fabricated via an electrostatic self-assembly multilayer method, and composite films of gold nanoparticle dispersed in silica matrix were formed by heat-treating the polyelectrolyte/gold nanoparticle/silica nanoparticle composite films to eliminate the polyelectrolyte. The obtained composite films were investigated with UV-vis, TEM, AFM and XRD. The results show that the self-assembly multilayer method is a promising process to produce composite films of gold nanoparticle-dispersed in organic and/or inorganic matrixes.
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    TeOx Thin Films for Write-Once Optical Recording Media
    Qinghui LI, Donghong GU, Fuxi GAN
    J. Mater. Sci. Technol., 2004, 20 (06): 678-680. 
    Abstract   HTML   PDF (277KB)
    TeOx thin films were prepared by vacuum evaporation of TeO2 powder. Structural characteristic and surface morphology of the as-deposited films was analyzed by using X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray diffractometer and atomic force microscopy. It was found that the films represented a two-component system comprising Te particles dispersed in an amorphous TeO¬2 matrix. The dispersed Te particles were in a crystalline state. The TeO¬x films showed a finely granular structure and a rough surface. Results of the static recording test showed that the TeO¬x films had good writing sensitivity for short-wavelength laser beam (514.5 nm). Primary results of the dynamic test at 514.5 nm were also reported. The TeO¬x films were suitable for using as a blue-green wavelength high density optical storage medium.
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    A HRTEM and XRD Study of the Potassium Hexatitanate Nanowires
    Bingshe XU, Peide HAN, Jian LIANG, Yuan YU, Huiqiang BAO, Xuguang LIU
    J. Mater. Sci. Technol., 2004, 20 (06): 681-683. 
    Abstract   HTML   PDF (436KB)
    The structure of potassium hexatitanate (K¬¬2T¬6O¬13) nanowires has been investigated using both the Rietveld powder diffraction profile fitting technique and high resolution transmission electron microscopy (HRTEM) image simulations. From the Rietveld analysis it was shown that the nanowires had a monoclinic structure of the space group C2/M and the lattice parameters were a=1.5582 nm, b=0.382 nm, c=0.9112 nm. HRTEM conclusions agree with refinement results obtained from experimental XRD data. The good agreement between the experimental and simulated images confirms that the nanowires is indeed K¬¬2T¬6O¬13 nanowire.The growth axes of nanowires were mainly along the [010] direction.
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    Single Crystal Fe Nanowire Arrays Encapsulated by SiO2 Nanotubes
    Qing LIN, Lianzeng YAO, Guowei JIANG, Chuangui JIN, Weifeng LIU, Weili CAI, Zhen YAO
    J. Mater. Sci. Technol., 2004, 20 (06): 684-686. 
    Abstract   HTML   PDF (273KB)
    Aligned silicon dioxide nanotubes with diameter of 60~70 nm were synthesized inside the nanoholes of an anodic Al membrane (AAM) template by pressure impregnating the AAM pores with the SiO¬2 sol. The SiO¬2 nanotubes with different wall thickness were produced by repeating the process. Using the second-order template of porous AAM with silicon dioxide nanotubes, it was fabricated the nanostructure of Fe nanowires encapsulated by SiO¬2 nanotubes by electrochemical deposition. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observations show that the nanotubes and nanocables are compact, continuous and uniform. Selected area electron diffraction (SAED) pattern shows the Fe nanowire is a single crystal. The magnetic properties of these samples were checked by a vibrating sample magnetometer (VSM). The coercivities of the samples are greatly improved compared to the corresponding bulk materials.
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    Nanophase Decomposition of a Zn-Al Based Alloy Zn¬68Al¬10Cu¬22
    Y.H.Zhu, W.B.Lee, S.To
    J. Mater. Sci. Technol., 2004, 20 (06): 687-690. 
    Abstract   HTML   PDF (474KB)
    The nanostructural evolution and phase transformation of the films of a Zn-Al based alloy (Zn¬68Al¬10Cu¬22 in wt pct) have been studied by using X-ray diffraction and scanning electron microscopy. Nanostructural thin films of the Zn-Al based alloy were produced by using an electron beam deposition technique. It was found that a nanocrystalline phase ηn' had a strong preferred crystal orientation at (0002) crystal planes in the as-deposited films. During ageing at 220℃, the decomposition of nanophase ηn' started with clustering to form Z-zones, and transitional phase, which was accompanied by an eutectoid decomposition of the ηn' phase: ηn' →βeut'+T'. Decomposition, such as clustering and the formation of the Z-zones, and the transitional phase etc. were observed in the nanophaseβeut'. The formation and the decomposition of the transitional phase of micrometers in size were involved in the decomposition of the main nanophase ηn'. The mechanism of the Z-zones formation and the stability of nanophases were discussed.
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    Strain Softening and Hardening Behavior in AZ61 Magnesium Alloy
    Haitao ZHOU, Liufa LIU, Qudong WANG, Da LU, Xiaoqin ZENG, Wenjiang DING
    J. Mater. Sci. Technol., 2004, 20 (06): 691-693. 
    Abstract   HTML   PDF (490KB)
    The deformation behavior of AZ61 Mg alloy during hot deformation has been investigated in wide temperature and strain rate range by a Gleeble simulator. Specimens are deformed in compression in the temperature range of 523~673 K and at strain rates of 0.001~1 s¬¬¬-1. It is found that the flow curves exhibit a peak and then decrease towards steady-state of classical DRX, which decrease with rising temperature and decreasing strain rate. The deformation behavior of the specimens can be attributed to the occurrence of strain hardening and softening. As stress decreases, the strain hardening rate declines at a fast rate when temperature rises or strain rate decreases. The shapes of θ-σ curves indicate some important features such as subgrain formation, the critical stress, the peak stress and steady stress. The onset of DRX can be determined by the point of inflection on θ-σ or lnθ-σ curves.
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    Influence of Rolling Treatment on Interfacial Shear Strength of Steel-mushy Al-7graphite Bonding Plate
    Peng ZHANG, Yunhui DU, Hanwu LIU, Daben ZENG, Jianzhong CUI, Limin BA
    J. Mater. Sci. Technol., 2004, 20 (06): 694-696. 
    Abstract   HTML   PDF (209KB)
    At room temperature, the rolling treatment of steel-mushy Al-7graphite bonding plate was carried out under different relative reduction. The influence of rolling on interfacial mechanical property of this bonding plate was studied. The results show that, for steel-mushy Al-7graphite bonding plate which is made up of 1.2 mm in thickness 08Al steel plate and 2.0 mm in thickness Al-7graphite layer, there is a nonlinear relationship between interfacial shear strength of bonding plate and relative reduction of rolling. When relative reduction of rolling is smaller than 2.59%, with the increasing of relative reduction, interfacial shear strength of bonding plate increases gradually. When relative reduction of rolling is bigger than 2.59%, with the increasing of relative reduction, interfacial shear strength of bonding plate decreases continuously. When relative reduction of rolling is 2.59%, the largest interfacial shear strength 77.0 MPa can be obtained.
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    Martensitic Transformation in Magnetically Controlled Shape Memory Alloys Co50Ni20Ga30
    Fanbin MENG, Yangxian LI, Heyan LIU, Jingping QU, Ming ZHANG, Jinglan CHEN, Guangheng WU
    J. Mater. Sci. Technol., 2004, 20 (06): 697-700. 
    Abstract   HTML   PDF (444KB)
    The martensitic transformation for Co¬50Ni¬20Ga¬30 ribbon synthesized by the melt-spinning technique was studied by means of X-ray diffraction and ac magnetic susceptibility. The Co¬50Ni¬20Ga¬30 ribbon, having bcc phase with calculated lattice parameters of a=0.57431 nm at 313 K. It exhibits a structure transition from parent phase to martensite during cooling. The martensitic phase in Co¬50Ni¬20Ga¬30 ribbon is tetragonal structure with lattice parameters of a=b=0.5422 nm and c=0.6401 nm. (c/a>1). According to the changing of diffraction intensity for martensite and the change of ac magnetic susceptibility, the process of the martensitic transformation can be divided into three parts during cooling from 283 K to 213 K. When the temperature decreasing sequentially from 193 K to 110 K, the structure of the martensite has a change in which the a-axis decreases and c-axis increases. The morphologies of self-accommodation were observeds. The parallelogram morphology, the diamond morphology and the fork morphology were found.
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    On the Indeterminacy in Hardness of Shape Memory Alloys
    F.T.Cheng
    J. Mater. Sci. Technol., 2004, 20 (06): 700-702. 
    Abstract   HTML   PDF (195KB)
    The present communication addresses an interesting problem related to the indeterminacy in hardness of superelastic NiTi reported by Xu et al. The origin of the indeterminacy is attributed to the inadequacy of the conventional Vickers hardness testing measurement which does not record elastic deformation, and thus the indeterminacy may be removed with suitable techniques. Concepts of hardness in relation to deformation are clarified. Recommendations for measuring the hardness of NiTi and other elastic-plastic materials are suggested, together with comments on the advantages and disadvantages of each of these methods.
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    Annealing High Resistivity CdZnTe Wafers under Controlled Cd/Zn Partial Pressures
    Wanwan LI, Wenbin SANG, Bin ZHANG, Jiahua MIN, Fang YU
    J. Mater. Sci. Technol., 2004, 20 (06): 703-706. 
    Abstract   HTML   PDF (408KB)
    In order to improve the performances of CdZnTe γ-ray detector, it is key issue to get the crystal with high quality. Equilibrium partial pressures, pCd and pZn, over Cd1-xZnx melt were estimated based on thermodynamic relationship and then Cd0.9Zn¬0.1Te wafers were annealed under controlled Cd/Zn partial pressures provided by Cd¬1-xZnx alloy reservoir. The experimental results show that when CdZnTe wafers are annealed under the equilibrium partial pressures provided by Cd¬0.99Zn¬0.01 alloy reservoir for 5 days or more at 1073 K, the resistivity of the wafer can be raised by 6 times and IR transmittance raised by 10% or more, the size and density of Te precipitates are greatly reduced. Moreover, losing of Zn from the surface can be avoided, which leads to improvement of the Zn radial distribution. In addition, the relationship between the electrical performances of the wafers and different controlled pressures is also discussed.
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    Electrical Performance of Electron Irradiated SiGe HBT and Si BJT
    Wentao HUANG, Jilin WANG, Zhinong LIU, Peiyi CHEN, Peihsin TSIEN, Xiangti MENG
    J. Mater. Sci. Technol., 2004, 20 (06): 706-708. 
    Abstract   HTML   PDF (441KB)
    The change of electrical performances of 1 MeV electron irradiated silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied. After electron irradiation, both the collector current IC and the base current IB changed a little, and the current gain βdecreased a little for SiGe HBT. The higher the electron irradiation fluence was, the lower the IC decreased. For conventional Si BJT, IC and IB increased as well as βdecreased much larger than SiGe HBT under the same fluence. The contribution of IB was more important to the degradation of βfor both SiGe HBT and Si BJT. It was shown that SiGe HBT had a larger anti-radiation threshold and better anti-radiation performance than Si BJT. The mechanism of electrical performance changes induced by irradiation was preliminarily discussed.
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    Sliding Friction of Al-Cu-Fe-B Quasicrystals
    Xiying ZHOU, Peiyao LI, Junming LUO, Shiqiang QIAN, Jianhua TONG
    J. Mater. Sci. Technol., 2004, 20 (06): 709-713. 
    Abstract   HTML   PDF (485KB)
    Dry sliding friction between the Al¬59Cu¬25.5Fe¬12.5B¬3 quasicrystals (QCs)/coating of the diamond-like carbon (DLC) was carried out by self-made tribometer under different conditions. The influences of four parameters (temperature, sliding velocity, applied load, atmosphere) on friction and wear of quasicrystal surface were studied. Microstructure of quasicrystal, morphology of worn surface, and wear debris were observed by scanning electron microscopy (SEM). The results showed that for QCs, the friction coefficient and roughness of worn surface were influenced by the parameters, especially greatly by the temperature. With rise of the applied load and sliding velocity, the friction coefficient decreased. The dominant wear mechanism at 350℃ was delamination for QCs. The cracks formed on the worn surface during the friction. Moreover, phase transformation was not observed on worn surface of QCs at 350℃. All the results are discussed and explained.
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    Development and Oxidation Behavior of Al-Cu-Fe Quasicrystalline Coating on Ti Alloy
    Fei CAI, Chungen ZHOU, Huibin XU, Shengkai GONG
    J. Mater. Sci. Technol., 2004, 20 (06): 713-715. 
    Abstract   HTML   PDF (420KB)
    An oxidation resistant Al-Cu-Fe quasicrystalline coating was fabricated on substrate of Ti alloy by low pressure plasma spraying (LPPS) method. As-sprayed Al-Cu-Fe coating has a rapidly solidified lamellar microstructure consisting of quasicrystalline phase and crystalline phase. The formation of quasicrystalline coating is related to the annealing. The results from the oxidation experiments showed that Al-Cu-Fe quasicrystalline coating improved the oxidation resistance of Ti-base alloys. During the oxidation period there is no evident spallation of the coating from the substrate. Oxide formed on the surface of Al-Cu-Fe quasicrystalline coating after oxidation consisted of Al¬2O¬3. Oxidation occurs leading to a change of concentration and phase transformation in the coating surface. Selective oxidation of Al transforms the quasicrystalline phase into the phase.
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    Surface Nanocrystallization of Commercial Pure Titanium Induced by SMAT and Its Properties
    Shulan ZHANG, Huaining CHEN, Quanhong LIN
    J. Mater. Sci. Technol., 2004, 20 (06): 716-718. 
    Abstract   HTML   PDF (242KB)
    In this paper the preparation technique of surface nanocrystallization in commercial pure titanium was carried out by surface mechanical attrition treatment (SMAT). The mean grain size was calculated by using X-ray diffraction (XRD) and transmission electron microscope (TEM), and the results showed that the mean grain size of the surface was refined to nm level after SMAT treatment. Nanocrystallized surface layers were formed after treated for 5, 15, 30 and 60 min. Microhardness experimental results implied the microhardness obviously increased on the surface layer and it also showed the variation of microhardness at the cross section. Corrosion test results showed the corrosion resistance of the surfaces in the original commercial pure titanium treated by SMAT was not improved in HCl solution. The corrosion micrographs were observed by scanning electron microscope (SEM).
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    Oxygen Permeation Behaviors and Hardening Effect of Titanium Alloys at High Temperature
    Hongyan MA, Maocai WANG, Weitao WU
    J. Mater. Sci. Technol., 2004, 20 (06): 719-723. 
    Abstract   HTML   PDF (578KB)
    In order to improve the surface hardness and wear resistance of Ti and Ti alloy components, an oxygen permeation treatment (OPT) was developed. The oxygen permeation behaviors of three Ti alloys, TA2, TB5 and TC11, treated in air with O-P medium at high temperature have been studied. The results show that the O-P treatment can significantly improve the surface hardness of Ti alloys. The oxidation mass-gain of β-Ti alloy (TB5) is much higher than α-Ti alloy (TA2) under the same condition, while α+βTi alloy (TC11) is the lowest. All the Ti alloys treated at this condition produce two surface layers: the outer layer consists mainly of TiO¬2, as well as trace of other oxides, and the inner layer consists of a Ti-O interstitial solid solution formed by the diffusion of oxygen in α crystal lattice. Thick scales of βTi alloy (TB5) are easily formed depending mainly on the poor solid solution content of oxygen, while deep solution layer can be formed since partial β phase has been transformed into α phase. The scales of α-βTi alloy (TC11) are very thin and compact. Aluminum-rich zone, as well as deficient zone, is found in oxide layers. A crystallographic characterization of oxygen solution layer has been performed and evaluated by crystallographic lattice constant.
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    Protective Effect of the Sputtered TiAlCrAg Coating on the High-Temperature Oxidation and Hot Corrosion Resistance of Ti-Al-Nb Alloy
    Yanjun XI, Fuhui WANG, Lianlong HE
    J. Mater. Sci. Technol., 2004, 20 (06): 724-727. 
    Abstract   HTML   PDF (333KB)
    The effect of a sputtered Ti-48Al-8Cr-2Ag (at. pct) coating on the oxidation resistance of the cast Ti-46.5Al-5Nb (at. pct) alloy was investigated in air at 1000~1100℃. Hot corrosion in molten 75 wt pct Na¬2SO¬4+25 wt pct K¬2SO¬4 was investigated at 900℃. The scale on the cast TiAlNb tends to spall in air, while the scale on coating is very adherent. The sputtered Ti-48Al-8Cr-2Ag coating remarkably improved high temperature oxidation resistance of the cast Ti-46.5Al-5Nb alloy because of the formation of an adherent Al¬2O¬3 scale. Due to the inward diffusion of Cr, Kirkendall voids were found at the coating/substrate interface. TiAlCrAg coating provided excellent hot corrosion resistance for TiAlNb alloy in molten 75 wt pct Na¬2SO¬4+25 wt pct K¬2SO¬4 at 900℃ due to the formation of a continuous Al¬2O¬3 scale.
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    Aging Kinetics in a CuNiSiCr Alloy
    Jingguo LEI, Ping LIU, Xiaotian JING, Dongmei ZHAO, Jinliang HUANG
    J. Mater. Sci. Technol., 2004, 20 (06): 727-730. 
    Abstract   HTML   PDF (351KB)
    The aging precipitation behavior in solution treated Cu-Ni-Si-Cr alloy has been studied in terms of the analyses of the variations in electrical conductivity. On the basis of the linear relationship between the electrical conductivity and the volume fraction of the precipitates, the phase transformation kinetics equation was deduced from the Avrami empirical formula. On the basis of this equation, transformation kinetics curves corresponding to 5% and 50% transformation were established.
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    Interfacial Microstructure between WC-Based Cermet and Cu Alloy
    Xinhong WANG, Zengda ZOU, Sili SONG, Shiyao QU
    J. Mater. Sci. Technol., 2004, 20 (06): 731-734. 
    Abstract   HTML   PDF (538KB)
    A WC-TiC-Co/CuZnNi composite layer was produced on 1045 steel substrate by means of inside-furnace brazing technique. The microstructure, phase constituent and interfacial diffusion behavior between cermet and CuZnNi alloy were investigated by means of scanning electron microscopy (SEM), transmission electron microscope (TEM), electron probe microanalyzer (EPMA) and X-ray diffraction. The results showed that microstructure of matrix was α and βphases. Cermet particles were surrounded by the α+βphases in the composite layer and their sizes were almost similar to those in original state. The interfacial zone was formed by the mutual diffusion of elements under the condition of high temperature. The interface consists of WC, TiC, CuZn, and CuNi phases, and there are no microcracks and inclusions near the interface.
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    Influence of Bias on the Properties of Carbon Nitride Films Prepared by Vacuum Cathodic Arc Method
    Zhimin ZHOU, Lifang XIA, Mingren SUN
    J. Mater. Sci. Technol., 2004, 20 (06): 735-738. 
    Abstract   HTML   PDF (392KB)
    Carbon nitride films have been synthesized in a wide range of biases from 0 to -900 V by vacuum cathodic arc method. The N content was about 12.0~22.0 at. pct. Upon increasing the biases from 0 to -100 V, the N content increased from 15.0 to 22.0 at. pct which could be attributed to the knot-on effect. While the further increasing biases led to the gradual falling of the N content to 12.0 at. pct at -900 V due to the enhancement of the sputtering effect. Below -200 V, with the increasing biases the sp2¬¬¬¬¬¬¬¬¬C fraction in the films decreased, as a result of which the I(D)/I(G) fell in the Raman spectra and the sp peaks also showed the decreasing tendency relative to the s peaks in the VBXPS (valence band X-ray photoelectron spectroscopy). While above -200 V, the sp2C fraction increased and the films became graphitinized gradually, accompanying which the I(D)/I(G) rose from -200 V to -300 V and the Raman spectra even showed the graphite characteristic above -300 V and the sp peaks rose again relative to the s peak. The carbon nitride films mainly consist of three types of bonding: CC, sp2CN and sp3CN bonds. In the first stage the sp3CN relative ratio rises and falls in the second stage, which corresponded well with the variation of the sp2C in the films. The subplantation mechanism resulting from the effect of ion energy played an important role in deciding the variation of the microstructure of the carbon nitride films.
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    Determination of Feature Line Equation for Self-adapting Incremental Press Bending
    Jinsong LIU, Shihong ZHANG, Yuansong ZENG, Zhiqiang LI, Wei WU, Zhongtang WANG, Yi XU, Limei REN
    J. Mater. Sci. Technol., 2004, 20 (06): 739-742. 
    Abstract   HTML   PDF (279KB)
    The basic idea and method about determination of the feature line equations and how to apply them to the numerical control of the press bending of panel skins were introduced. Research indicates that it is feasible to realize the self-adapting incremental press bending by adopting the feature line equation. The feature line equation, which is based on the database of the status of practical processes, can be adjusted in time, and the forming precision can be improved. It is important to correctly select and reasonably predict the feature line equations to enhance the accuracy of the incremental press bending based on the feature line database and algorithm. The determination of the feature line equation settles necessary data foundation for further research on the database of self-adapting incremental press bending, and it supplies a new clue for the development of self-adapting incremental press bending.
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    Ab initio Calculations of the Formation Energies of Lithium Intercalations in SnSb
    Zhufeng HOU, Aiyu LI, Zizhong ZHU, Meichun HUANG, Yong YANG
    J. Mater. Sci. Technol., 2004, 20 (06): 743-745. 
    Abstract   HTML   PDF (249KB)
    SnSb has attracted a great attention in recent investigations as an anode material for Li ion batteries. The formation energies and electronic properties of the Li intercalations in SnSb have been calculated within the framework of local density functional theory and the first-principles pseudopotential technique. The changes of volumes, band structures, charge density analysis and the electronic density of states for the Li intercalations are presented. The results show that the average Li intercalation formation energy per Li atom is around 2.7 eV.
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    Piezoresistivity in Carbon Fiber Reinforced Cement Based Composites
    Bing CHEN, Keru WU, Wu YAO
    J. Mater. Sci. Technol., 2004, 20 (06): 746-750. 
    Abstract   HTML   PDF (780KB)
    The results of some interesting investigation on the piezoresistivity of carbon fiber reinforced cement based composites (CFRC) are presented with the prospect of developing a new nondestructive testing method to assess the integrity of the composite. The addition of short carbon fibers to cement-based mortar or concrete improves the structural performance and at the same time significantly decreases the bulk electrical resistivity. This makes CFRC responsive to the smart behavior by measuring the resistance change with uniaxial pressure. The piezoresistivity of CFRC under different stress was studied, at the same time the damage occurring inner specimens was detected by acoustic emission as well. Test results show that there exists a marking pressure dependence of the conductivity in CFRC, in which the so-called negative pressure coefficient of resistive (NPCR) and positive pressure coefficient of resistive (PPCR) are observed under low and high pressure. Under constant pressures, time-dependent resistivity is an outstanding characteristic for the composites, which is defined as resistance creep. The breakdown and rebuild-up process of conductive network under pressure may be responsible for the pressure dependence of resistivity.
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    Damage Effect of Space Proton Irradiation with the Low Energy of 50~200 keV on Methyl Silicone Rubber
    Lixin ZHANG, Chengmin WANG, Shiyu HE
    J. Mater. Sci. Technol., 2004, 20 (06): 751-754. 
    Abstract   HTML   PDF (433KB)
    The damage effects and mechanisms of proton irradiation with 50~200 keV energy to space-grade methyl silicone rubber was performed using a ground-based simulator for space irradiation environment. The changes in surface morphology, mechanical properties, cross-linking density, glass temperature, infrared attenuated total reflection spectrum, mass spectrum and pyrolysis gas chromatography-mass spectrum indicated that, under lower energy, the proton irradiation would induce cross-linking effect, resulting in an increase in tensile strengths and hardness of the methyl silicon rubber. However, after the irradiation of protons for more than 150 keV, the irradiation induced degradation, which decreased the tensile strengths and hardness, became a dominant effect. A macromolecular network destruction model for the silicone rubber radiated with the protons was proposed.
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    Microstructures and Toughness of Weld Metal of Ultrafine Grained Ferritic Steel by Laser Welding
    Xudong ZHANG, Wuzhu CHEN, Cheng WANG, Lin ZHAO, Yun PENG, Zhiling TIAN
    J. Mater. Sci. Technol., 2004, 20 (06): 755-759. 
    Abstract   HTML   PDF (580KB)
    3 mm thick 400 MPa grade ultrafine grained ferritic steel plates were bead-on-plate welded by CO¬2 laser with heat input of 120~480 J/mm. The microstructures of the weld metal mainly consist of bainite, which form is lower bainite plates or polygonal ferrite containing quantities of dispersed cementite particles, mixed with a few of low carbon martensite laths or ferrite, depending on the heat input. The hardness and the tensile strength of the weld metal are higher than those of the base metal, and monotonously increase as the heat input decreases. No softened zone exists in heat affected zone (HAZ). Compared with the base metal, although the grains of laser weld are much larger, the toughness of the weld metal is higher within a large range of heat input. Furthermore, as the heat input increases, the toughness of the weld metal rises to a maximum value, at which point the percentage of lower bainite is the highest, and then drops.
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    A Simulator for Producing of High Flux Atomic Oxygen Beam by Using ECR Plasma Source
    Shuwang DUO, Meishuan LI, Yaming ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 759-762. 
    Abstract   HTML   PDF (307KB)
    In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016~1017 atoms•cm-2•s-1 and energy of 5~30 eV and a cross section of Φ80 mm could be obtained under the operating pressure of 10¬-1~10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.
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    Welding TiB¬2 Ceramics and Metal Mo with Combustion Reaction Technology
    Daihua HE, Zhengyi FU, Qingjie ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 763-766. 
    Abstract   HTML   PDF (397KB)
    Combustion reaction welding, one promising method to weld ceramics and metals, was used to weld TiB¬2 and Mo. The results showed that the reacted products through combustion reaction were TiB¬2 and MoB when the Mo contents in reactants were 20 wt pct and 40 wt pct while there was Mo besides MoB and TiB¬2 when there were 60 wt pct and 80 wt pct Mo in reactants. Diffusion of elements occurred at the interfaces of the two substrates. The interfaces between the reacted and the two substrates were indistinct after being welded. The welding temperature strongly affected properties of the samples. The value of bending strength of the sample with 80 wt pct Mo in reactant welded at 1500℃ was the highest, 368.52 MPa. The highest value of shear strength among all the samples was that of the one with 40 wt pct Mo in reactant welded at 1500℃, 50.97 MPa.
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    Precipitating Mechanism of Carbide in Cold-Welding Surfacing Metals
    Yuanbin ZHANG, Dengyi REN
    J. Mater. Sci. Technol., 2004, 20 (06): 766-768. 
    Abstract   HTML   PDF (266KB)
    Carbides in a series of cold-welding weld metals were studied by means of SEM, TEM and EPMA, and the forming mechanism of carbide was proposed according to their distribution and morphology. Due to their different carbide-forming tendency, Nb and Ti could combine with C to form particulate carbide in liquid weld metal and depleted the carbon content in matrix, while V induced the carbide precipitated along grain boundary. But too much Nb or Ti alone resulted in coarse carbide and poor strengthened matrix. When suitable amount of Nb, Ti and V coexisted in weld metal, both uniformly distributed particulate carbide and well strengthened matrix could be achieved. It was proposed that the carbide nucleated on the oxide which dispersed in liquid weld metal, and then grew into multi-layer complex carbide particles by epitaxial growth. At different sites, carbide particles may present as different morphologies.
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    Cold Plasma Surface Modification of NiTi for Biomedical Applications
    Jun YANG, Jianhua WANG
    J. Mater. Sci. Technol., 2004, 20 (06): 769-771. 
    Abstract   HTML   PDF (265KB)
    Surface-grafted poly(ethylene glycol) (PEG) molecules are known to prevent protein adsorption to the surface. Nitinol samples were coated under tetraglyme ECR cold plasma conditions to enhance its biocompatibility. The modified Nitinol surfaces were characterized by high resolution ESCA and contact angle, it was demonstrated that the deposited PEG-like coatings were built up mainly of –CH¬2-CH¬2-O- linkages in surfaces. The surface wettability of the modified Nitinol was increased compared with the control surface. Human plasma protein was adsorbed on Nitinol evaluated by SEM, the protein adsorption on modified surfaces decreased rapidly. Thus, the potential benefits of cold plasma technique will be of use to the biomedical industries improving the biocompatibility of metals.
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    Formation and Characterization of Bone-like Nanoscale Hydroxyapatite in Glass Bone Cement
    Qiang FU, Nai ZHOU, Wenhai HUANG, Deping WANG, Liying ZHANG
    J. Mater. Sci. Technol., 2004, 20 (06): 772-774. 
    Abstract   HTML   PDF (381KB)
    Glass based bone cement (GBC) was synthesized by mixing CaO-SiO¬2-P¬2O¬5 based glass powder with ammonium phosphate liquid medium. Bone-like hydroxyapatite (HAP, Ca¬10(PO¬4)¬6(OH¬2) was found to form after GBC was immersed in simulated body fluid (SBF). HAP crystal grew with an increasing time along c axle and reached about 200 nm in length after 30~days, however, the end plane granularity remained 30~50 nm. The chemical composition, crystal structure and morphology of HAP formed from GBC were proved to have great resemblance with living HAP. It is believed that GBC was a desirable biomedical material with high bioactivity. Furthermore, the high compressive strength guaranteed the possibility of GBC in clinical application.
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    Adiabatic Shear Bands in 30CrNi¬3MoV Structural Steel Induced during High Speed Cutting
    Chunzheng DUAN, Minjie WANG
    J. Mater. Sci. Technol., 2004, 20 (06): 775-778. 
    Abstract   HTML   PDF (338KB)
    The width and spacing of adiabatic shear bands (ASBs) in the serrated chips generated during high speed orthogonal cutting of 30CrNi¬3MoV structural steel were measured by optical microscopy (OM), the temperature rise in the shear band was estimated. The microstructures of the ASBs were also characterized by SEM and TEM. The results show that the width and spacing of ASBs decrease with the increase of the cutting speed. The further observations show that the microstructure between the matrix and the center of the ASB gradually changes, and that the martensitic phase transformation, carbide precipitation and recrystallization may occur in the ASB.
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    Processing of Ultralow Carbon Pipeline Steels with Acicular Ferrite
    Furen XIAO, Mingchun ZHAO, Yiyin SHAN, Bo LIAO, Ke YANG
    J. Mater. Sci. Technol., 2004, 20 (06): 779-781. 
    Abstract   HTML   PDF (334KB)
    Acicular ferrite microstructure was achieved for an ultralow carbon pipeline steel through the improved thermomechanical control process (TMCP), which was based on the transformation process of deformed austenite of steel. Compared with commercial pipeline steels, the experimental ultralow carbon pipeline steel possessed the satisfied strength and toughness behaviors under the current improved TMCP, although it contained only approximately 0.025% C, which should mainly be attributed to the microstructural characteristics of acicular ferrite.
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    Selection of Parameters in Ball-Spinning
    Maosheng LI, Yongnian YAN, Shihong ZHANG, Dachang KANG
    J. Mater. Sci. Technol., 2004, 20 (06): 782-787. 
    Abstract   HTML   PDF (663KB)
    Nowadays, with the development of spinning processes, more and more systematic research about spinning parameters has been published. Based on these results, a routing about how to select spinning parameters has been gradually formed. However, ball spinning, due to its own features plus research lack, is still unclear about its parameter selections. In addition, some manufacture-enterprises only notice the use of this technique whereas ignore the theory creation. The optimal parameters about the ball spinning although have been released from these enterprises but in fact not a helpful theory for other researchers and producers. Focus on selecting the parameters based on the trial-and-error, this article has carried a series of experiments to study the influence on the spinning working course from those parameters, especially the peeling phenomena, and the tube diameter bulging. An optimal graph of the working angle, the axial feeding rate, and the acceptable working course is put forward. Additionally, based on the theory of the minimal reduction rate, the selection of the ball diameter is finally described. Thus, it has given the rules to get the proper parameters in ball spinning.
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    Polybutylacrylate/poly (methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part II Toughness on DGEBA/DDM system
    Jianli WANG, Myonghoon LEE, Kejian YAO, Jianbin JI, Xiaomei YU
    J. Mater. Sci. Technol., 2004, 20 (06): 787-790. 
    Abstract   HTML   PDF (415KB)
    Mechanical properties of epoxy resin were investigated by adding core-shell elastic particles (CSEP). The results indicated that optimized core-shell ratio was 60/40 and the loading volume of CSEP was 10 phr (per hundred parts of epoxy resin by weight). The impact strength of modified systems increased apparently with the decrease of core sizes. However, the shearing strength changed gently with the particle sizes. CSEP with lightly crosslinked rubbery core showed more effectiveness on toughness than others. With solution blending, CSEP could be dispersed in epoxy matrix well, and the morphologies of dispersed rubber domains were controlled perfectly by CSEP whose structure was predesigned. A cavitation-shearing band toughness mechanism was observed from the SEM micrographs of fracture surface. It also was found that the deforming temperature (DT) of modified epoxy did not decline apparently.
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    Synthesis of La¬0.9Sr¬0.1Ga¬0.8Mg¬0.2O3-δ Powder for Solid Oxide Fuel Cell by a Nitrate-Citrate Combustion Route
    Naiqing ZHANG, Kening SUN, Derui ZHOU, Ningning WU
    J. Mater. Sci. Technol., 2004, 20 (06): 791-793. 
    Abstract   HTML   PDF (381KB)
    A nitrate-citrate combustion route to synthesize La¬0.9Sr¬0.1Ga¬0.8Mg¬0.2O3-δ powder for solid oxide fuel cell application was presented. This route is based on the gelling of nitrate solutions by the addition of citric acid and ammonium hydroxide, followed by an intense combustion process due to an exothermic redox reaction between nitrate and citrate ions. The optimum technical parameters are that the pH value is 5, and the molar ratio of citric acid to the total metallic ion is 1.5:1. X-ray diffraction characterization of calcined gel shows that pure phase was synthesized after calcination at 1400℃ for 10 h, and the TEM result shows the calcined powder with average particle size is about 150 nm. The grain resistance contributes to the total resistance of sintered pellet below 500℃. The conductivity of the sintered pellet at 800℃ was 0.07 s-1•cm-1 higher than the conductivity of YSZ (0.05 s-1•cm-1 at 800℃)
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    Influence of Solid Fraction on Structure of QTi3.5-15/Graghite Slurry
    Peng ZHANG, Yunhui DU, Hanwu LIU, Daben ZENG, Jianzhong CUI, Limin BA
    J. Mater. Sci. Technol., 2004, 20 (06): 794-796. 
    Abstract   HTML   PDF (237KB)
    The electromagnetic-mechanical stirring technology was used to prepare QTi3.5-15/graghite slurry. The distribution of graphite particles in QTi3.5-15/graghite slurry was studied using cold quenching method. The results show that solid fraction of QTi3.5-15/graphite slurry increases with the decreasing of stirring temperature. There is a linear relationship between solid fraction and stirring temperature. With the increasing of solid fraction, the distribution of graphite particles in slurry becomes uniform gradually. When the solid fraction is larger than 45%, the rising of graphite particles in slurry can be restricted, and QTi3.5-15/graghite slurry with uniform distribution of graphite particles can be prepared.
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    Development of Al¬2O¬3/TiN Ceramic Cutting Tool Materials by Artificial Neural Networks
    Ning FAN, Xiangbo ZE, Zihui GAO
    J. Mater. Sci. Technol., 2004, 20 (06): 797-800. 
    Abstract   HTML   PDF (228KB)
    The artificial neural networks (ANN) which have broad application were proposed to develop multiphase ceramic cutting tool materials. Based on the back propagation algorithm of the forward multilayer perceptron, the models to predict volume content of composition in particle reinforced ceramics are established. The Al¬2O¬3/TiN ceramic cutting tool material was developed by ANN, whose mechanical properties fully satisfy the cutting requirements.
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    A Generalized Yield Criterion
    Shijian YUAN, Dazhi XIAO, Zhubin HE
    J. Mater. Sci. Technol., 2004, 20 (06): 800-802. 
    Abstract   HTML   PDF (201KB)
    A generalized yield criterion is proposed based on the metal plastic deformation mechanics and the fundamental formula in theory of plasticity. Using the generalized yield criterion, the reason is explained that Mises yield criterion and Tresca yield criterion do not completely match with experimental data. It has been shown that the yield criteria of ductile metals depend not only on the quadratic invariant of the deviatoric stress tensor J¬2, but also on the cubic invariant of the deviatoric stress tensor J3 and the ratio of the yield stress in pure shear to the yield stress in uniaxial tension k/σ¬s. The reason that Mises yield criterion and Tresca yield criterion are not in good agreement with the experimental data is that the effect of J¬3 and k/σ¬s is neglected.
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