2007年, 第17卷, 第04期　刊出日期：2007-04-25

  

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  Effects of sintering pressure and temperature on microstructure and tribological characteristic of Cu-based aircraft brake material

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  中国有色金属学报（英文版）. 2007, 17(04): 669-669.

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   A novel Cu-based P/M aircraft brake material was prepared and the effects of sintering pressure and temperature on microstructure and tribological characteristic were investigated. For the constant sintering temperature, when the sintering pressure increases from 0.5 MPa to 1.5 MPa, the porosity, wear loss and friction coefficient decrease remarkably. When the sintering pressure increases from 1.5 MPa to 2.5 MPa, the porosity further decreases but in a little degree and wear behaviors are improved slightly. However, once the sintering pressure is larger than 2.5 MPa, it has no obvious effect on microstructure and tribological characteristic. For the constant sintering pressure, when the sintering temperature increases from 900 ℃ to 930 ℃, the sintered density remarkably increases, and wear behaviors are obviously improved. For further increasing sintering temperature to 1 000 ℃, the density keeps on increasing, but wear behaviors change slightly.
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  Modeling corrosion behavior of gas tungsten arc welded titanium alloy

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  中国有色金属学报（英文版）. 2007, 17(04): 676-676.

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  The pitting corrosion characteristics of pulse TIG welded Ti-6Al-4V titanium alloy in marine environment were explained. Besides the rapid advance of titanium metallurgy, this is also due to the successful solution of problems associated with the development of titanium alloy welding. The preferred welding process of titanium alloy is frequently gas tungsten arc(GTA) welding due to its comparatively easier applicability and better economy. In the case of single pass GTA welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The benefit of the process is utilized to obtain better quality titanium weldments. Four factors, five levels, central composite, rotatable design matrix are used to optimize the required number of experiments. The mathematical models have been developed by response surface method(RSM). The results reveal that the titanium alloy can form a protective scale in marine environment and is resistant to pitting corrosion. Experimental results are provided to illustrate the proposed approach.
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  Effect of adding methods of metallic phase on microstructure and thermal shock resistance of Ni/(90NiFe2O4-10NiO) cermets

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  中国有色金属学报（英文版）. 2007, 17(04): 681-681.

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  Ball mixing and electroless plating were respectively used as the adding methods of metallic phase to prepare Ni/(90NiFe₂O₄-10NiO) cermets for the inert anode in aluminum electrolysis. The microstructure and thermal shock resistance of cermet samples were studied. The results show that, for the samples prepared by ball mixing method, aggregation of metallic phase is found in either the green blocks or sintered samples and the extent of aggregation increases with the increase of metal content. For 6.5Ni/(90NiFe₂O₄-10NiO) cermets prepared with electroless plating method, the homogeneous and fine metallic particles are found in either the green compacts or sintered samples, but the relative density and thermal shock residual strength decrease by 3% and 28%−58% respectively, compared with samples prepared with ball mixing method.
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  Correlations between IMC thickness and three factors in Sn-3Ag-0.5Cu alloy system

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  中国有色金属学报（英文版）. 2007, 17(04): 686-686.

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  The effects of Ni content, soldering temperature and time on the IMC thickness in Sn-3Ag-0.5Cu and Sn-3Ag-0.5Cu-0.2Co alloys were researched using uniform design method and computer programs. For each alloy, the factors were divided into three levels in the experiment. Two correlative equations are given by regression. They indicate that the effects of three factors on the function are in the mutual and quadratic forms. And the analysis of variance shows the equations are sound and meaningful. Using the equations, it is easy to search, predict and control the IMC thickness. The existence of element Co accelerates the crystallization and growing up of IMC.
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  Effect of ultrasonic stirring on temperature distribution and grain refinement in Al-1.65%Si alloy melt

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  中国有色金属学报（英文版）. 2007, 17(04): 691-691.

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   A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. The cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. The influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. The results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. The effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.
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  Quantitative calculation of local shear deformation in adiabatic shear band for Ti-6Al-4V

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  中国有色金属学报（英文版）. 2007, 17(04): 698-698.

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   JOHNSON-COOK(J-C) model was used to calculate flow shear stress—shear strain curve for Ti-6Al-4V in dynamic torsion test. The predicted curve was compared with experimental result. Gradient-dependent plasticity(GDP) was introduced into J-C model and GDP was involved in the measured flow shear stress—shear strain curve, respectively, to calculate the distribution of local total shear deformation(LTSD) in adiabatic shear band(ASB). The predicted LTSDs at different flow shear stresses were compared with experimental measurements. J-C model can well predict the flow shear stress—shear strain curve in strain-hardening stage and in strain-softening stage where flow shear stress slowly decreases. Beyond the occurrence of ASB, with a decrease of flow shear stress, the increase of local plastic shear deformation in ASB is faster than the decrease of elastic shear deformation, leading to more and more apparent shear localization. According to the measured flow shear stress—shear strain curve and GDP, the calculated LTSDs in ASB are lower than experimental results. At earlier stage of ASB, though J-C model overestimates the flow shear stress at the same shear strain, the model can reasonably assess the LTSDs in ASB. According to the measured flow shear stress—shear strain curve and GDP, the calculated local plastic shear strains in ASB agree with experimental results except for the vicinity of shear fracture surface. In the strain-softening stage where flow shear stress sharply decreases, J-C model cannot be used. When flow shear stress decreases to a certain value, shear fracture takes place so that GDP cannot be used.
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  Effect of tube size on electromagnetic tube bulging

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  中国有色金属学报（英文版）. 2007, 17(04): 705-705.

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  The commercial finite code ANSYS was employed for the simulation of the electromagnetic tube bulging process. The finite element model and boundary conditions were thoroughly discussed. ANSYS/EMAG was used to model the time varying electromagnetic field in order to obtain the radial and axial magnetic pressure acting on the tube. The magnetic pressure was then used as boundary conditions to model the high velocity deformation of various length tube with ANSYS/LSDYNA. The time space distribution of magnetic pressure on various length tubes was presented. Effect of tube size on the distribution of radial magnetic pressure and axial magnetic pressure and high velocity deformation were discussed. According to the radial magnetic pressure ratio of tube end to tube center and corresponding dimensionless length ratio of tube to coil, the free electromagnetic tube bulging was studied in classification. The calculated results show good agreements with practice.
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  Isothermal section at 927 ℃ of Cr-Ni-Ti system

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  中国有色金属学报（英文版）. 2007, 17(04): 711-711.

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  The isothermal section at 927 ℃ of the Cr-Ni-Ti system was established using a high-efficiency diffusion couple approach, supplemented with eight equilibrated alloys. The alloy compositions were selected on the basis of the experimental results from the diffusion couple. Both the diffusion couple specimens and the alloys were examined by means of optical microscopy, scanning electron microscopy, and electron probe microanalysis. No ternary compound is found at 927 ℃. The following five three-phase equilibria are well determined: TiNi₃+(Cr)+(Ni), TiNi₃+(Cr)+TiNi, TiNi+(Cr)+Cr₂Ti, Ti₂Ni+Cr₂Ti+TiNi and Ti₂Ni+Cr₂Ti+(Ti). The solubilities of Cr in NiTi₂, NiTi, and Ni₃Ti are determined to be 7.5%, 14.5% and 11.4% (molar percent), respectively. α-Cr₂Ti and β-Cr₂Ti dissolve about 9.2% and 13.9% Ni (molar percent), respectively.
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  Effects of titanium coating on property of diamond

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  中国有色金属学报（英文版）. 2007, 17(04): 715-715.

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  The titanium film was coated on the surface of diamond crystal in order to improve the chemical properties of diamond and the effect of titanium coating on the property of diamond was discussed. The anti-impacting strength, the oxidization process and the soakage property between vitrified bond and diamond were investigated. It is found that, when the titanium film is coated on the surface of diamond crystal, the soakage angle between vitrified bond and diamond decreases from 39.5˚ to 34.5˚ at 993 K, and the oxidization degree on the surface of diamonds is lowered greatly.
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  Synthesis of γ-LiV2O5/VO2 mixture by thermal lithiation of vanadium (+4, +5) oxides

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  中国有色金属学报（英文版）. 2007, 17(04): 720-720.

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  γ-LiV₂O₅/VO₂ composites were synthesized through thermal lithiation reaction of mixed valence (+4, +5) vanadium oxides by lithium bromide. The phase evolution, morphology and discharge behavior at 500 ℃ were investigated by thermal gravimeter/differential thermal analysis (TG/DTA), X-ray diffraction(XRD), scanning electron microscopy(SEM) and specific surface analysis(BET). The mixed vanadium oxides are obtained from the pyrolytic decomposition of ammonium metavanadate, with V₆O₁₃ as main phase. Results show that the lithiation reaction begins at about 258 ℃, with γ-LiV₂O₅ and VO₂(B) as the product. VO₂(B) can transit to VO₂(R) in the range of 400−500 ℃, following by grain growth and crystalline development with the increase of temperature and roasting time. The ratio of γ-LiV₂O₅ to VO₂ can be modified by the additive content of lithium bromide. A lattice shearing model about the nucleation and growth of Li_xV₂O₅ and VO₂(B) inside mixed valence (+4, +5) vanadium oxides (e.g. V₆O₁₃, V₃O₇) is speculated, which is relative to oxygen-/vacancy-diffusion and structural evolution inspired by lithium-insertion. The open-circuit voltage of 2.6 V is observed in the single cell of Li-B/LiCl-KCl/(γ-LiV₂O₅/VO₂) at 500 ℃, and the specific capacities of 146 and 167 mA∙h/g (cut-off voltage 1.4 V) are measured for the positive material at 100 mA/cm² and 200 mA/cm², respectively.
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  Localized corrosion mechanism associated with precipitates containing Mg in Al alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 727-727.

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  To clarify the localized corrosion mechanism associated with precipitates containing Mg in Al alloys, the simulated bulk precipitates of S and β were synthesized through melting and casting. Their electrochemical behaviors and coupling behaviors with α(Al) in NaCl solution were measured. Meanwhile, simulated Al alloys containing S and β particles were prepared and their corrosion morphologies were observed. It’s found that there exist two kinds of corrosion mechanisms associated with precipitates containing Mg. The precipitate of β is anodic to the alloy base, resulting in its anodic dissolution and corrosion during the whole corrosion process. While, there exists a corrosion conversion mechanism associated with the S precipitate, which contains active element Mg and noble element Cu simultaneously. At an initial stage, S is anodic to the alloy matrix at its periphery and the corrosion occurs on its surface. However, during its corrosion process, Mg is preferentially dissolved and noble Cu is enriched in the remnants. This makes S become cathodic to α(Al) and leads to anodic dissolution and corrosion on the alloy base at its periphery at a later stage.
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  Diffusion barrier performance of nanoscale TaNx thin-film

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  中国有色金属学报（英文版）. 2007, 17(04): 733-733.

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  TaN_x nanoscale thin-films and Cu/TaN_x multilayer structures were deposited on P-type Si(100) substrates by DC reactive magnetron sputtering. The characteristics of TaN_x films and thermal stabilities of Cu/TaN_x/Si systems annealed at various temperatures were studied by four-point probe(FPP) sheet resistance measurement, atomic force microscopy(AFM), scanning electron microscope-energy dispersive spectrum (SEM-EDS), Alpha-Step IQ Profilers and X-ray diffraction(XRD), respectively. The results show that the surfaces of deposited TaN_x thin-films are smooth. With the increasing of N₂ partial pressure, the deposition rate and root-mean-square(RMS) decrease, while the content of N and sheet resistance of the TaN_x thin-films increase, and the diffusion barrier properties of TaN_x thin-films is improved. TaN_1.09 can prevent interdiffusion between Cu and Si effectively after annealing up to 650 ℃ for 60 s. The failure of TaN_x is mainly attributed to the formation of Cu₃Si on TaN/Si interface, which results from Cu diffusion along the grain boundaries of polycrystalline TaN.
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  Experimentation and thermodynamic modelling on SrZrO3

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  中国有色金属学报（英文版）. 2007, 17(04): 739-739.

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   Experimental data for the perovskite phase SrZrO₃ were subjected to a critical thermodynamic assessment using the CALPHAD approach. Special attention was paid to the structural behavior of SrZrO₃ to illustrate, how to select an appropriate thermodynamic model based on crystal structure and chemistry information, how to identify and resolve the inconsistency between various kinds of experimental data, and how to use thermodynamic modeling as a basic tool in the development and optimization of materials and process. Our assessment results in a Gibbs energy function covering the temperature range between 300 K and the melting point, which explains the experimental data within the experimental uncertainty.
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  Effect of minor Sc and Zr on superplasticity of Al-Mg-Mn alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 744-744.

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  The effect of Sc and Zr on the superplastic properties of Al-Mg-Mn alloy sheets was investigated by control experiment. The superplastic properties and the mechanism of superplastic deformation of the two alloys were studied by means of optical microscope, scanning electronic microscope and transmission electron microscope. The elongation to failure of Al-Mg-Mn-Sc-Zr alloy is larger than that of Al-Mg-Mn alloy at the same temperature and initial strain rate. The variation of strain rate sensitivity index is similar to that of elongation to failure. In addition, Al-Mg-Mn-Sc-Zr alloy exhibits higher strain rate superplastic property. The activation energies of the two alloys that are calculated by constitutive equation and linear regression method approach the energy of grain boundary diffusion. The addition of Sc and Zr decreases activation energy and improves the superplastic property of Al-Mg-Mn alloy. The addition of Sc and Zr refines the grain structure greatly. The main mechanism of superplastic deformation of the two alloys is grain boundary sliding accommodated by grain boundary diffusion. The fine grain structure and high density of grain boundary, benefit grain boundary sliding, and dynamic recrystallization brings new fine grain and high angle grain boundary which benefit grain boundary sliding too. Grain boundary diffusion, dislocation motion and dynamic recrystallization harmonize the grain boundary sliding during deformation.
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  Effect of crystallization on corrosion resistance of Cu52.5Ti30Zr11.5Ni6 bulk amorphous alloy

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  中国有色金属学报（英文版）. 2007, 17(04): 751-751.

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   The effects of crystallization on the corrosion resistance of a Cu52.5Ti30Zr11.5Ni6 bulk amorphous alloy in 1 mol/L HCl, and 6 mol/L NaOH solutions were studied. The amorphous alloy was identified by differential thermal analysis(DSC) and by X-ray diffraction(XRD). The partially and fully crystallized alloys were prepared by controlling the annealing temperatures at 738 and 873 K for 1 and 12 min, respectively, and the corrosion resistances of those annealed alloys were compared with that of the amorphous alloy by immersion test and potentiodynamic measurements in 1 mol/L HCl and 6 mol/L NaOH solutions. The results show that the partially crystallized alloy exhibits high corrosion resistance, whereas full crystallization results in deteriorated corrosion resistance compared with that of the as-cast amorphous alloy.
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  Growth and corrosion resistance of molybdate modified zinc phosphate conversion coatings on hot-dip galvanized steel

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  中国有色金属学报（英文版）. 2007, 17(04): 755-755.

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  The modified zinc phosphate conversion coatings(ZPC) were formed on hot-dip galvanized(HDG) steel when 1.0 g/L sodium molybdate were added in a traditional zinc phosphate solution. The growth performance and corrosion resistance of the modified ZPC were investigated by SEM, open circuit potential(OCP), mass gain, potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) measurements and compared with those of the traditional ZPC. The results show that if sodium molybdate is added in a traditional zinc phosphate solution, the nucleation of zinc phosphate crystals is increased obviously; zinc phosphate crystals are changed from bulky acicular to fine flake and a more compact ZPC is obtained. Moreover, the mass gain and coverage of the modified ZPC are also boosted. The corrosion resistance of ZPC is increased with an increase in coverage, and thus the corrosion protection ability of the modified ZPC for HDG steel is more outstanding than that of the traditional ZPC.
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  Electrocatalytic properties of Ni-S-Co coating electrode for hydrogen evolution in alkaline medium

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  中国有色金属学报（英文版）. 2007, 17(04): 762-762.

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  Amorphous Ni-S-Co alloy was prepared by means of chemical electro-deposition method on the foam nickel matrix. The surface morphology and microstructure of Ni-S-Co coatings were studied using SEM and XRD, and the electrochemical properties were tested by electrochemical methods. The results show that the coating has amorphous structure and the particles of the surface are fine with large specific surface area. The Ni-S-Co alloy is more active with lower potential for hydrogen evolution, higher exchange current density and lower activation energy compared with Ni and Ni-S electrode. Its hydrogen evolution reaction(HER) is enhanced, the size of particles of surface decreases and the surface area increases after being activated by KOH alkaline solution.
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  Electronic structure and physical properties of hcp Ti3Al type alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 766-766.

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  According to the basic information of sequences of Ti and Al characteristic atoms in hcp Ti-Al system, the compositional variations of the electronic structure, atomic potential energies, atomic volumes, lattice constants and cohesive energies of the ordered hcp Ti₃Al type alloys were calculated by the framework of systematic science of alloys(SSA). The electronic structure of the hcp Ti₃Al compound consisted of and  atoms is 0.75[Ar] (3d_n)^0.573(3d_c)^2.1685(4s_c)^0.972(4s_f)^0.3093+0.25[Ne](3s_c)^1.32∙ (3p_c)^1.19(3s_f)^0.49. The factors of controlling lattice stability are electronic structure, atomic energies and atomic concentration. The atoms play a determinative role in forming D0₁₉ structure with a=0.287 2 nm, c=0.456 4 nm, atomic cohesive energy ε=4.810 8 eV/atom and heat of formation ΔH=−0.332 8 eV/atom. These calculated values are in good agreement with experimental values (a=0.287 5 nm, c=0.46 0 nm, ∆H=−0.27, −0.29 eV/atom). The calculated cohesive energy of the hcp Ti₃Al compound is slightly bigger than that of the fcc Ti₃Al.This is a good sign that makes it feasible to stabilized L1₂ structure of the hcp Ti₃Al compound by ternary element. The new element should have more d_c-electrons than Ti-metal and occupy at the Ti-lattice points.
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  Effect of substrate temperature on structural properties and photocatalytic activity of TiO2 thin films

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  中国有色金属学报（英文版）. 2007, 17(04): 772-772.

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  Titanium dioxide (TiO₂) films with anatase structure were prepared on quartz glass substrates by pulse laser ablating titanium (99.99%) target under oxygen pressure of 10 Pa at substrate temperature of 500−800 ℃. The structural properties of the films were characterized by X-ray diffractometry(XRD), X-ray photoelectron spectroscopy(XPS) and field emission scan electron microscopy(FESEM). The results show that, as the substrate temperature is increased from 600 ℃ to 800 ℃, the anatase structure of the films changes from random growth to (211)-oriented growth. The absorption edge tested by UV-Vis Spectrometer has a blue shift. The photocatalytic activity of the films was tested on the degradation of methyl orange. It is found that the film with random growth structure exhibits better photo-degradation efficiency than that with (211)-oriented growth structure.
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  Macro-microscopic morphology and phase analysis of TiAl-based alloys sheet fabricated by EB-PVD method

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  中国有色金属学报（英文版）. 2007, 17(04): 777-777.

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  TiAl-based alloys sheet with thickness of 0.3−0.4 mm as well as dimension of 150 mm×100 mm was fabricated successfully by using electron beam-physical vapor deposition(EB-PVD) method. The microscopic morphology and phase composition of specimens in various states were analyzed by atomic force microscope(AFM), scanning electron microscope(SEM) and X-ray diffractometer(XRD), respectively. The results indicate that the as-deposited TiAl-based alloys sheet has good surface quality and is composed of γ, α₂ and τ phase. There is natural delamination inside the sheet, of which the microstructure is columnar crystal, and the component shows a gradient change along the normal direction of substrate. After the vacuum hot pressing treatment and subsequent homogenization treatment, the columnar crystal transforms into the coarse fully lamellar microstructure, the delamination phenomenon and τ phase disappear, α₂ phase decreases obviously, and the composition tends to uniformization.
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  Controlled synthesis of highly ordered CuO nanowire arrays by template-based sol-gel route

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  中国有色金属学报（英文版）. 2007, 17(04): 783-783.

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  The highly ordered CuO nanowire arrays of composite-oxides were synthesized within a porous anodic aluminum oxide(AAO) template by a citrate-based sol-gel route. A vacuum system was applied to draw the gel into the template pores, which conquers the only driving force of this technique—capillary action, then the gel was thermally treated to prepare desired CuO nanowires. The results of scanning electron microscopy(SEM) indicate that the CuO nanowires are very uniformly assembled and parallel to each other in the pores of the anodic aluminum oxide(AAO) template membranes. The results of X-ray diffraction(XRD) and the selected-area electron diffraction(SAED) indicate that the CuO nanowires are monoclinic-type crystalline structure. Furthermore, X-ray photoelectron spectroscopy (XPS) demonstrates that the stoichiometric CuO is formed.
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  Effect of Zr content on quench sensitivity of AlZnMgCu alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 787-787.

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  The effect of Zr content on quench sensitivity of AlZnMgCu alloys was investigated by mechanical properties testing and microstructure observations. The results show that with the increase of Zr the quench sensitivity relative to hardness and strength increases, while that relative to elongation decreases. From hardness and strength viewpoints, the low quench sensitivity is observed for the Zr-free and 0.05% Zr-containing alloys, which is quite quench sensitive from the ductility viewpoint. The largest quench sensitivity relative to hardness and strength is observed for 0.1% Zr-containing alloy, this is mainly due to large amount of high angle grain boundaries and incoherent Al₃Zr dispersoids caused by recrystallization, which may efficiently promote heterogeneous precipitation during air quenching. More than 0.05% Zr consignificantly decrease the quench sensitivity relative to ductility, which can be primarily attributed to recrystallization inhibiting and grain refining effects of Zr.
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  General issues of FEM in backward ball spinning of thin-walled tubular part with longitudinal inner ribs

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  中国有色金属学报（英文版）. 2007, 17(04): 793-793.

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  Backward ball spinning was applied for manufacturing thin-walled tubular parts with longitudinal inner ribs. Rigid-plastic finite element method(FEM) was used for simulating the backward ball spinning process in order to calculate the height of the inner ribs. With a view to guarantee a better simulation accuracy, it is essential to enhance and improve some general problems of FEM, such as generation of initial velocity field, choice of penalty factor, determination of boundary conditions, treatment of rigid region and description of convergence criteria. It is evident that whether the problems with respect to FEM are dealt with appropriately or not, they have a significant influence on the modeling accuracy and efficiency. By reasonable solving the general problems, rigid-plastic FEM can successfully simulate the height of the inner ribs and the calculated values are in good agreement with the measured values.
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  Preparation of semi-solid slurry containing fine and globular particles for wrought aluminum alloy 2024

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  中国有色金属学报（英文版）. 2007, 17(04): 799-799.

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  The semi-solid slurry of wrought aluminum alloy 2024 was prepared by a well developed rheocasting process, low superheat pouring with shearing field(LSPSF). The appreciate combination of pouring temperature and rotation speed of barrel, can give rise to a transition of the growth morphology of primary α(Al) from coarse-dendritic to coarse-particle-like and further to fine-globular. The combined effects of both localized rapid cooling and vigorous mixing during the initial stage of solidification can enhance wall nucleation and nuclei survival, which leads to the formation of fine-globular primary α(Al). By using semi-solid slurry prepared by LSPSF, direct squeeze cast cup-shaped component with improved mechanical properties such as yield strength of 198 MPa, ultimate tensile strength of 306 MPa and elongation of 10.4%, can be obtained.
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  Effect of cerium on microstructure and mechanical properties of Sn-Ag-Cu system lead-free solder alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 805-805.

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  The melting point, spreading property, mechanical properties and microstructures of Sn-3.0Ag-2.8Cu solder alloys added with micro-variable-Ce were studied by means of optical microscopy, scanning electron microscopy(SEM) and energy dispersive X-ray(EDX). The results indicate that the melting point of Sn-3.0Ag-2.8Cu solder is enhanced by Ce addition; a small amount of Ce will remarkably prolong the creep-rupture life of Sn-3.0Ag-2.8Cu solder joint at room temperature, especially when the content of Ce is 0.1%, the creep-rupture life will be 9 times or more than that of the solder joint without Ce addition; the elongation of Sn-3.0Ag-2.8Cu solder is also obviously improved even up to 15.7%. In sum, the optimum content of Ce is within 0.05%−0.1 %.
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  Failure mechanism of EB-PVD thermal barrier coatings on NiAl substrate

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  中国有色金属学报（英文版）. 2007, 17(04): 811-811.

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  Yttria stabilized zirconia(YSZ) was deposited on the line cut β-NiAl substrate by electron-beam physical vapour deposition(EB-PVD), and the cyclic oxidation behaviors of thermal barrier coatings on β-NiAl substrate were investigated in 1 h thermal cycles at 1 200 ℃ in air. The results show that the samples fail after 80−100 cycles. Sub-interface cavitations in the substrate develop due to depletion of Al in forming thermally grown oxides(TGOs). The collapse and closing up of cavities result in the ragged YSZ/TGO/substrate interface. Since the specific crack trajectories are quite sensitive to local geometry, cracks along the YSZ/TGO/substrate interfaces ultimately lead to YSZ spallation.
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  Cycle stability of La0.7Mg0.3Ni2.55−xCo0.45Cux (x=0−0.4) electrode alloys

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  中国有色金属学报（英文版）. 2007, 17(04): 816-816.

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  The La_0.7Mg_0.3Ni_2.55−xCo_0.45Cu_x (x=0, 0.1, 0.2, 0.3, 0.4) electrode alloys were prepared by casting and rapid quenching. Ni in the alloy was partially substituted by Cu in order to improve the cycle stability of La-Mg-Ni system (PuNi₃-type) hydrogen storage alloy. The effects of substituting Ni with Cu on the microstructures and cycle stability of the alloys were investigated in detail. The results obtained by XRD, SEM and TEM show that the substitution of Cu for Ni is favourable for the formation of an amorphous in the as-quenched alloy, and this leads to an obvious refinement of the as-quenched alloy grains and a growth of the lattice constants and cell volumes of the as-cast and quenched alloys. The results obtained by the electrochemical measurement indicate that the cycle stability of the alloys significantly rises with the incremental variety of Cu content. When Cu content changes from 0 to 0.4, the cycle lives of the as-cast and quenched (30 m/s) alloys are enhanced from 72 to 88 cycles and from 100 to 121 cycles, respectively.
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  Preparation of nanocrystal modificator and its modification mechanism

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  中国有色金属学报（英文版）. 2007, 17(04): 823-823.

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  In order to increase the modifying effect, the Cu-P master alloy was rapidly solidified with melt-spin method, and the nano-sized ribbon was gained at 10⁵−10⁶ ℃/s. Subsequently, ZL109 alloy was modified by nanocrystal and massive Cu-P master alloy, respectively, with molten metal casting method. The results show that the microscopic structure of ZL109 alloy modified by nanocrystal Cu-P master alloy is better than that modified by massive Cu-P master alloy, the original crystal silicon and eutectic silicon are refined more effectively and the mechanical properties are increased evidently: the tensile-strength is increased by 25%, the elongation is increased by 32.26% and the hardness is increased by 17.2%. Therefore, the melt-spin treatment is a feasible method to improve the modifying effect of Cu-P master alloy.
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  Bioactivity of mica/apatite glass ceramics

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  中国有色金属学报（英文版）. 2007, 17(04): 828-828.

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  The bioactivity of mica/apatite glass ceramic composites, including the in vitro behavior in simulated body fluid and the histological appearance of the interface between the mica/apatite glass ceramics and the rabbit mandible defect in vivo under a dynamic condition. The results show that biological apatite layer forms on the surface of the mica/apatite glass ceramics after 1 d of immersion in the simulated body fluid, and becomes dense after 14 d. In vivo tests indicate that bone formation occurs after implantation for 14 d, and strong bonding of bone to the implant occurs after 42 d. No aseptic loosening occurs during 42 d of implantation. The finding shows that mica/apatite glass ceramics have good bioactivity and osteoconductivity for constructing bone graft, and can be promising for biomedical application.
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  Adsorption of Ag(Ⅰ) on H2TiO3 from aqueous solutions

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  中国有色金属学报（英文版）. 2007, 17(04): 832-832.

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  Adsorption of silver ions from aqueous solution onto H₂TiO₃ was studied. Equilibrium experimental studies were performed to determine the adsorption capacity of H₂TiO₃ for silver ion at various pH values. Batch experiments were conducted in the range of pH value 3−7 and silver ions concentration 10−200 mg/L. The results show that the adsorption is strongly dependent on pH value. The equilibrium absorption capacity of H₂TiO₃ increases significantly with the increase of pH value from 3 to 7. The adsorption of silver ion obeys the Langmuir isothermal equation well in the concentration range studied, the adsorption constant is 0.054 7, 0.052 4, 0.088 1 at pH 5, 6 and 7, respectively, and the maximum adsorption capacities are 23.64, 29.76 and 40.82 mg/g.
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  Influence of calcination atmosphere on photocatalytic reactivity of K2La2Ti3O10 for water splitting

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  中国有色金属学报（英文版）. 2007, 17(04): 836-836.

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  The layered perovskite type oxide K₂La₂Ti₃O₁₀ powders were prepared under air, Ar and H₂ calcination atmospheres by sol-gel method and characterized by X-ray diffractometry, UV-Vis diffuse reflectance and X-ray photoelectron spectroscopy. The influence of the calcination atmosphere on the photocatalytic reactivity of K₂La₂Ti₃O₁₀ for hydrogen production was investigated. The photocatalytic reactivity of K₂La₂Ti₃O₁₀ prepared under air, Ar and H₂ atmospheres was compared with that prepared under ultraviolet and visible light radiation using I^? as electronic donor. The results show that K₂La₂Ti₃O₁₀ prepared under Ar and H₂ atmospheres has higher photocatalytic activity for hydrogen production than that prepared under air atmosphere. The hydrogen production rates under ultraviolet irradiation are 127.5, 81.3 and 57.0 μmol/(L?h) and those under visible light irradiation are 40.2, 30.2 and 16.5 μmol/(L?h) respectively when K₂La₂Ti₃O₁₀ is prepared under Ar, H₂ and air atmospheres.
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  Effect of graphite content on electrochemical performance of Sn-SnSb/graphite composite powders

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  中国有色金属学报（英文版）. 2007, 17(04): 841-841.

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  Sn-SnSb alloy was synthesized by reducing a aqueous solution containing Sn(Ⅱ) and Sb(Ⅲ) salts with NaBH₄ in the presence of sodium citrate. The product was characterized by X-ray diffractometry(XRD) and scanning electron microscopy(SEM). Sn-SnSb/graphite composite powders were prepared by mechanical milling and the mass fraction of graphite was increased from 20% to 50%. The effect of graphite content on the electrochemical performance of Sn-SnSb/graphite composite electrode was investigated. The results show the increase of graphite content is in favor of enhancing the first charge-discharge efficiency and improving the cycle performance, but the capacity of the composite electrode decreases with increasing content of graphite.
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  Effects of added Cd on Cd uptake by oilseed rape and pai-tsai co-cropping

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  中国有色金属学报（英文版）. 2007, 17(04): 846-846.

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  Spectra of sodium aluminate solutions

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  中国有色金属学报（英文版）. 2007, 17(04): 853-853.

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  The UV spectra of sodium aluminate solutions were obtained in the sodium oxide concentration range from 59 to 409 g/L and the caustic ratio range from 1.5 to 4.0 to reveal the structure characteristics of them. It is found that a new peak appears at about 370 nm besides peaks at about 220 and 266 nm in all solutions. The new peak is strongly favored by high hydroxide concentration and high caustic ratio. And it only appears when the solutions are prepared by dissolving sodium hydroxide and aluminum hydroxide. In addition, the IR and Raman spectra of sodium aluminate solutions with high alkali concentration and high caustic ratio were measured, and the UV spectra of aqueous solutions of and were measured as well. According to the crystal field theory in coordination chemistry as well as the above spectra characteristics, this new peak at about 370 nm is determined as the evidence of a new species of aluminate ion with a coordination number of 6.
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  A novel recovery technology of trace precious metals from waste water by combining agglomeration and adsorption

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  中国有色金属学报（英文版）. 2007, 17(04): 858-858.

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  A novel and efficient technology for separating and recovering precious metals from waste water containing traces of Pd and Ag was studied by the combination of agglomeration and adsorption. The recovery process and the impacts of operating conditions such as pH value of waste water, adsorption time, additive quantity of the flocculant and adsorbent on the recovery efficiency were studied experimentally. The results show that Freundlich isothermal equation is suitable for describing the behavior of the recovery process, and the apparent first-order adsorption rate constant k at 25 ℃ is about 0.233 4 h⁻¹. The optimum technology conditions during the recovery process are that pH value is 8−9; the volume ratio of flocculant to waste water is about   1׃(2 000−4 000); the mass ratio of adsorbent to waste water is 1׃(30−40); and processing time is 2−4 h. Finally, the field tests were done at the optimum technology conditions, which show that the total concentration of Pd and Ag in the waste water below 11 mg/L can be reduced to be less than 1 mg/L.
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  Reaction process of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl2

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  中国有色金属学报（英文版）. 2007, 17(04): 864-864.

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  The decomposition reactions of monazite and bastnaesite mixed rare earth minerals calcined by CaO-NaCl-CaCl₂ were studied by means of TG-DTA and XRD. The results show that the process of the minerals decomposed by CaO involves two steps. The first step occurs in the temperature range of 425−540 ℃, and the main reactions are bastnaesite decomposition, i.e. REOF  reacts with CaO to produce RE₂O₃ and CaF₂, and Ce₂O₃ is oxidized to CeO₂. During this step, CaCO₃ is formed at about 500 ℃. The second step takes place in the temperature range of 610−700 ℃, and the reactions are monazite decomposition into RE₂O₃, Ca₅F(PO₄)₃ and Ca₃(PO₄)₂ by CaO and CaF₂. In this process, the decomposition ability is improved because CaO from CaCO₃ decomposing has high chemical activity. In calcining process, the new formed Ca₅F(PO₄)₃ restrains fluorine that can escape in form of gaseous compound. The decomposition ratio of the mixed rare earth minerals reaches 90.8% at 700 ℃.
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  Adsorption of XSD-296 resin for Cr(Ⅵ)

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  中国有色金属学报（英文版）. 2007, 17(04): 869-869.

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  The adsorption properties of XSD-296 for Cr(Ⅵ) were studied by using chemical analysis and infrared spectrometry. Experimental results show that XSD-296 resin has a good adsorption ability for Cr(Ⅵ) at pH=2.6 in the HAc-NaAc medium. The statically saturated adsorption capacity is 235 mg/g resin. The apparent activation energy of adsorption reaction, E_a, is 16.73 kJ/mol, and the thermodynamic parameters are ∆H=11.62 kJ/mol, ∆G_{298 K}=−4.13 kJ/mol. The adsorption behavior of resin for Cr(Ⅵ) is in accordance with Freundlich adsorption isotherm. Cr(Ⅵ) adsorbed on resin can be eluted by 5%NaCl-5%NaOH or 5%NH₄Cl-5%NH₃∙H₂O quantitatively. Infrared spectra and adsorption mechanism show that the functional group of resin coordinates with Cr(Ⅵ) to form co-ordination compound. The coordination molar ratio of the functional group of resin to Cr(Ⅵ) is 1׃1.
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  Preparation and properties of Ce0.8Ca0.2O1.8 anode material by glycine-nitrate process

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  中国有色金属学报（英文版）. 2007, 17(04): 874-874.

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  Ce_0.8Ca_0.2O_1.8 (CDC82) anode material was prepared by glycine-nitrate process(GNP). Thermogravimetric(TG) analysis and differential scanning calorimetric(DSC) methods were adopted to characterize the reaction process of CDC82 material. X-ray diffractometry(XRD), scanning electron microcopy(SEM), direct current four probe (four-probe DC) and temperature process reduce(TPR) techniques were adopted to characterize the properties of CDC82 material. After the precursor was sintered at 750 ℃ for 4 h, CDC82 material with pure-fluorite structure and nanometer size was obtained. The total conductivity of CDC82 changes little with temperature in air at 50−850 ℃, and the maximum value is 0.04 S/cm at 750 ℃. The total conductivity wholly becomes larger when the atmosphere changes from air to hydrogen, which greatly increases with increasing temperature and reaches the maximum value of 1.09 S/cm at 850 ℃. Some impurities such as CeMg and La₂O₃ exist after the mixture of CDC82 anode and La_1−xSr_xGa_1−yMg_yO_3−δ (LSGM) electrolyte material is sintered at 1 200 ℃ for 15 h. The CDC82 material as anode material has excellent catalytic property for hydrogen and methane.
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  Degradation of anthraquinone dyes by ozone

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  中国有色金属学报（英文版）. 2007, 17(04): 880-880.

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  The decolorization of three kinds of anthraquinone dyes by ozone was investigated and the residues in the degradation solution were analyzed. The results indicate that the decolorizing effects are obvious with the decolorization efficiency of dyes all above 96% in 40 min. The pH value and TOC concentration decline while the conductivity increases with the lapse of reaction time. The complicated dye molecules are decomposed to simple compounds with —SO₃H, —Cl in the dye molecules transformed into Cl⁻, and nitrogen partially degrades into according to the bases of different groups. The organic acids are found in the degradation solutions and dyes with larger relative molecular mass are decomposed into substances with larger relative molecular mass.