15 December 2012, Volume 43 Issue 23

    

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研究与开发
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  Study of the hot-pressing process and properties of microwave absorbing materials for isolator load

  Xiao-Hu REN;

  . 2012, 43(23): 1-0.

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  The microwave absorbing composites with epoxy resin as matrix and carbonyl iron (CI) power as absorber were prepared by hot pressing process. The microstructure, electromagnetic characteristics and absorbing properties of prepared composite were measured, and the properties of isolator fabricated with this composite were studied. The results show that the microwave absorbing composites with high density and absorption loss can be obtained by choosing appropriate content of absorber under an optimum pressure. The absorption loss of the composites with 65vol. % of CI molded under 30MPa is 7.8~8.9dB?mm-1 in the frequency range of 8-12GHz.When the voltage standing wave ratio is less than 1.2,for the isolator with the prepared composite as load, the isolation is not less than 20dB accompanied with a relative bandwidth of 25%.
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  Preparation and electrochemical performance of NiCo2O4/C material for supercapacitors

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  . 2012, 43(23): 2-0.

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  NiCo2O4/C nanoparticles were prepared by Solid phase sintering method. The structure of synthesized NiCo2O4/C was characterized using X-ray diffraction (XRD), which shows the material belongs to cubic spinel structure. The morphology of NiCo2O4/C by scanning electron microscopy (SEM) was proved to be a spherical particle with a uniform size distribution, and the particle size of grain was in the range of 30 to 40nm. The electrochemical performances of NiCo2O4/C electrodes were investigated by cyclic vohammetry and galvanostatic charge/discharge testing in 6mol/L KOH solution. The results showed that the specific discharge capacitance of NiCo2O4/C electrode was 290.49F/ g between 0 and 0.9V potential at 50mA/g current density.
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  Synthesis and Characterization of High Quality Water-soluble CdTe Quantum Dots

  wang yilin lin ;;

  . 2012, 43(23): 3-0.

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  Mercaptosuccinic acid (MSA) -capped CdTe quantum dots (QDs) were prepared in an aqueous medium with CdCl2 and TeO2 as raw materials, and NaBH4 as reductant. The influence of refluxing time and tellurium to cadmium molar ratio on the luminescent properties of the obtained CdTe QDs were investigated, and the obtained QDs were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy and fluorescent spectroscopy, respectively. The results showed that the CdTe QDs were of zinc-blended crystal structure in a sphere-like shape. The absorption and fluorescence spectra of QDs shifted to longer wavelengths with the increasing of refluxing time. The CdTe QDs with the emission color ranging from green to red could be prepared at pH= 10.5, n (Cd ):n (Te ):n (MSA) = 1:0.05:1.4 within 5 h., the maximum quantum yield was 70.3 %.
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  Preparation of Mixed-activated Carbon from the Off-silicon Rice Husk

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  . 2012, 43(23): 4-0.

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  The off-silicon rice husk ash has been used to prepare activated carbon by mixed activation, through the materials ratio experiments of four single activators, determines the best material ratio is 1:3,designs five mixed activation ratio experiments, the experimental results show that the iodine adsorption value and methylene blue adsorption can be the best, when NaOH& Na2CO3 and KOH of K2CO3 mixed ratio is 2.5:0.5, respectively, adding the auxiliary activator can effectively improve the adsorption value of rice husk activated carbon. Under the established conditions, three single factor experiments of the mass fraction of the impregnating solution, the activation temperature and activation time were done, results showed that: the iodine value can up to 1528.76mg/g under the conditions of activation time for 40 min, the mass fraction of the impregnating solution with 30%, the activation temperature at 500℃, shows the mixed activation has a significantly role on the preparation of rice husk activated carbon.
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  Synthesis of Nanosize TiO2 Hollow Sphere via Acid Catalytic Hydrolysis-Hydrothermal Method

  ;;Shou-Xin Liu

  . 2012, 43(23): 5-0.

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  TiO2 hollow spheres were synthesized by combined acid catalytic hydrolysis-hydrothermal method. TiO2 precursor was deposited on the surface of carbon spheres obtained by hydrothermal method using glucose as starting material. SEM, TEM, XPS, XRD and N2 adsorption-desorption were used to characterize the samples. TiO2 hollow spheres were obtained by calcination under atmosphere after the core carbon sphere was burnt off and TiO2 precursor trasformes from uncrystalline to anatase simultaneously. The results revealed that the size and surface morphology of TiO2 hollow spheres can be controlled by adjusting the concentration of glucose aqueous solution. With the increasing of cocentration of glucose solution, the diameter of TiO2 hollow sphere increased. TiO2 hollow sphere prepared with glucose concentration of 0.7 mol/L is size uiniform, with the diameter of 200nm, and the thickness of TiO2 shell 28nm. The photocatalytic activity of TiO2 hollow sphere is higher than TiO2 made by the same method without using template (TiO2-G0). The phenol removal rate of the sample prepared by calcination at 600℃ is as 1.35 times high as that of TiO2-G0.
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  Effects of Annealing Treatment of CCS on Interface Diffusion and Bonding Strength

  . 2012, 43(23): 6-0.

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  The method adopted to manufacture CCS wire in this study is pressing and cladding by two copper strips. The annealing treatment of CCS were studied, effects of annealing temperature and time of CCS on interface diffusion and bonding performance were discussed. The results show that the diffusion thickness and bonding strength are increased with the increase of annealing temperature and time. Compared with annealing time, annealing temperature has more effect on it. When the annealing temperature is 750 oC, annealing time is 2 h, the interface is effect. The interface diffusion layer thickness and bonding strength are invirable when continuing to increase the temperature and extend the time. Calculate the diffusion activation energy of Fe and Cu atoms and diffusion constant by diffusion equation, the relationship of diffusion constant and annealing temperature is conformed. According to the relation of diffusion layer thickness and bonding strength and the requirement of actual producing, the best annealing process is 750 oC/2 h.
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  Effect of SD binder on microstructure and mechanical properties of Ti(C, N)-based cermets

  Du-Juan YANG ;

  . 2012, 43(23): 7-0.

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  Effect of SD binder on contents of carbon，phase composition，microstructure and mechanical properties of the Ti(C,N)-based cermets which prepared by the low pressure sintering technology were determined through chemical analysis，X-ray diffraction (XRD), back scattering scanning electron microscopy (BSE) and Energy Dispersive Spectrometer (EDS)，respectively. The conclusions are as follows: the total carbon content of cermets compacts after debinding increases and the nitrogen content decreases as the SD binder increases. There are only two phases, (Ti, Me)(C,N)(Me=W, Mo, Ta) and Ni/Co solid solution existing in the Ti(C,N)-based cermets after sintering. The alloy exhibits a big volume fraction of black core-white rim structure. Meanwhile, small amount of white core-grey rim structure also exists. The preferable synthetically mechanical properties with transverse rupture strength of 1929MPa and a hardness of 1588HV30 can be obtained when 100ml/kg of SD binder is added. When the addition of SD binder is 180ml/kg, the graphite phase appears, causing significant decrease in the transverse rupture strength.
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  Shear Strain Induced Piezoresistivity in CFRP

  Hua-Sheng Zheng ;;;

  . 2012, 43(23): 9-0.

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  The film-like carbon fiber reinforced plastic (CFRP) sample was attached to the base component to invest its resistance response to pure shear strain in elastic range by a self-made device. The results suggested that shear strain doesn’t induce obvious longitudinal resistance response for the unidirectional carbon fiber reinforced CFRP for its small gauge factor of 0.16. A prominent shear strain induced piezoresistivity of a gauge factor of 2.58 was revealed for carbon fiber mat reinforced CFRP, which manifests as the resistance increasing with the shear strain with good linearity and reversibility. By the comparison with the mechanism of normal strain induced piezoresistivity and the analysis on the micro structure, the paper reaches the conclusion that the random directions of carbon fibers and the morphological diversity of the carbon fiber junctions are the chief cause for the shear strain induced piezoresistivity of carbon fiber mat reinforced CFRP.
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  Fabrication and properties of polyimide dielectric films via solution polycondensation

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  . 2012, 43(23): 10-0.

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  Biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-diaminodiphenyl ether (ODA) used as monomer reaction products and the polyimide (PI) dielectric films have been successfully fabricated via solution polycondensation. The structure and surface morphology of PI dielectric films prepared in different imidization temperature were characterized by XRD、SEM and FTIR. The influence that the imidization temperature and powder content (BPDA and ODA) affected on the breakdown field was measured by current testing instrument with high resistance techniques. The experimental results show that Polyimide acids (PAA) are completely aminated and become PI dielectric films with compact internal structure after imidization temperature of 300℃ for 1 hour under vacuum environment of 1.0×10-2Pa. The breakdown field can reach up to 2.15 MV/cm when powder content of BPDA and ODA is fixed to 5%, which indicates that PI dielectric films have good electrical properties.
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  CdZnTe thick films deposited by close-spaced sublimation and its properties

  ; Junning Gao;

  . 2012, 43(23): 11-0.

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  Polycrystalline CdZnTe thick films were deposited on glass substrates via close-spaced sublimation(CSS) technique. The morphology, composition, micro-structure, optical and electrical properties of CdZnTe thick films were investigated by SEM, EDS, XRD, UV spectrophotometer, and I-V mesurements. It is found that the grains are uniform, also, the grain sizes increase significantly with increasing deposition time. The XRD results show that all the thick films possess cubic structure, and tend to grow along the orientation of (111) face. The optical energy gap of all the thick films are in the region of 1.53～1.56eV. The resistivity of the films are 1010 Ω·cm orders of magnitude, and have good optical response. It can be used for counting detectors.
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  The influence of different content of Cr on microstructure and properties of WC-Co cemented carbide

  Jun ZHU; ;Jia Yang

  . 2012, 43(23): 12-0.

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  WC-8Co cemented carbide added with different content of Cr was obtained by the low pressure sintering technology. The microstructure, phase of the alloys were studied by using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD),and compared the mechanical properties. The experiment results show that, when the content of Cr was inferior to 0.9%, the microstructure of alloys consisted of WC and γ solid solution. As the content of Cr reached 0.9%, the ternary W3Co3C phase emerged; the growth of WC grains was inhibited sufficiently. The better synthetically mechanical property was obtained by addition of 0.6%.the bending strength, Vickers hardness and fracture toughness were: 3885MPa, 1632.4HV30, 9.82MPa·m1/2.
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  Effects of reducing agent on microwave absorption properties of HGM/Ni-P core/shell particles

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  . 2012, 43(23): 13-0.

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  Based on the NaH2PO2 as reducing agent, Ni-P layer was deposited on the surface of microspheres by electroless plating, getting the lightweight hollow glass microspheres/Ni-P core/shell particles (referred to as HGM/Ni-P core/shell particles). The phase structures, morphologies, particle size, shell thickness, chemical compositions and the microwave absorbing properties of the core-shell particles have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS) and Vector network analyzer (VNA), respectively. The results showed that with the increaseing of the reducing agent, surface morphology of HGM/Ni-P core/shell particles shows few different, but P content of shell layer increases, and amorphous structure in the shell change, amorphous ingredients increase. The dielectric properties and magnetic permeability of HGM after plating is greatly improved. As the concentration of NaH2PO2 increased from 20g/L to 30g/L, the resonance peak of ε′ and ε″ moved to higher frequency, as the concentration of NaH2PO2 got to 40g/L, the resonance peak disappeared and the dielectric constant reduced. Meanwhile, the fluctuation of μ′ and μ″ at 6-8GHz disappeared as the NaH2PO2 increased.
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  Research on microstructure and property of In-situ of Mg2Sip/Al composites

  Yu-Ying

  . 2012, 43(23): 14-0.

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  Abstract：The Mg2Sip/Al composites were fabricated with melt direct reaction method. The effect of Mg2Si particle content and heat treatment by solution treatment at 530℃ for 6h followed by artificial ageing at 173℃ for 5h on microstructure and performance of the composites were investigated, the phase contents and the microstructure of the composites were analyzed by XRD, SEM and EDS, and the mechanical properties were then tested. The results indicate that the grain size of the matrix of the as-cast composites are getting smaller with increasing particle content; the composite with a nominal Mg2Si particle content of 4wt% after heat treatment precipitates more second phase particles than the composite with a nominal Mg2Si particle content of 5wt%, and the average size of second phase particles in both of them are about 4μm. After heat treatment, the tensile strength and the elongation of the composite with a nominal Mg2Si content particle of 4wt% reach 280MPa and 9% which are 21.7% and 63.6% higher than those before heat treatment, respectively.
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  Effect of Annealing Temperature on Structural and Optical Properties of Sol-Gel Prepared Titanium Dioxide Thin-Films

  ;Guoqiang Li

  . 2012, 43(23): 15-0.

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  Titanium dioxide films were prepared on silica and quartz substrates by Sol-Gel dip-coating. These films were subsequently thermally annealed at temperatures for 30min. The structural and optical properties of prepared titanium dioxide films were analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectrophotometer, respectively. The ability to degrade methyl orange of these films was also studied. We found that the crystalline phase of the changed gradually from anatase to rutile as annealing temperature increased, and this transition took place at temperatures ranging from 700 to 800℃. During the transition, titanium dioxide films exhibited good, and no cracks were found even after annealing at 800℃. As annealing temperature increased, the absorption peak of titanium dioxide films had a blue-shifted, resulting in the expansion of absorption range in UV area. Titanium dioxide film prepared by this method and annealed at 800℃ for 30min which contained 31.4% anatase (mass ratio) showed the highest degradation ratio of methyl orange.
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  Study of a novle alkaline barrier slurry applied in copper chemical mechanical planarization

  Wen-Hao WEI

  . 2012, 43(23): 16-0.

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  In this paper, we have developed an alkaline barrier slurry for barrier removal applied in copper chemical mechanical planarization（CMP）. Firstly, we have studied the characteristics of removal rate and selectivity of Ta/TEOS/Cu under the same process condition. The results indicate that copper has a low removal rate during barrier CMP by using this slurry, it will protect the copper films from directly dissolution, Ta and TEOS has high removal rate selectivity to Cu, thus it may be helpful to modify the dishing and erosion. The pattern wafer results reveal that the alkaline barrier slurry has a strong modify effect on dishing and erosion reduction, and can be useful applied in barrier CMP.
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  Effect of rf powers on microstructural characteristics and optical properties of nc-Si:H thin films by RF-PECVD

  . 2012, 43(23): 17-0.

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  The hydrogenated nanocrystalline silicon (nc-Si:H) films were fabricated on quartz substrates by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) method with the substrate temperature of 250°C, H2 dilution ratio of 99%, the reaction pressure of 133Pa and rf power of 20W-60W, using SiH4 and H2 as the gas source. The microstructures and optical properties of thin films were studied by alpha-step instrument, X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform infrared spectroscopy (FTIR) and transmission spectrum .The results show that, with the increasing of rf power, the nc-Si:H deposition rate increased, the crystallization rate and grain size also increased, and the hydrogen content would decrease. Simultaneously, the absorption coefficient of the films was enhanced, the optical band gap became narrow, the structural order was enhanced and the width of the band tail would decrease.
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  IA/AA/AMPS coal-water slurry preparation and characterization of dispersant

  . 2012, 43(23): 18-0.

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  e coal-water slurry dispersant was prepared by 2-Acrylamide-2-methylpro panesulfonic acid (AMPS)，acrylic acid (AA) and itaconic acid (IA)（Terpolymer）. Through the viscosity curves which was characteristic of this coal dispersant， The best synthetic conditions had been determined: monomer ratio : w (AMPS) : w (AA) : w (IA) = 3.8:1:1， reaction temperature 85℃， the adding amount of initiator and sodium hypophosphite was 5% and 10% amount of monomers， respectively. The copolymer was characterized and analyzed by IR 、XRDand GPC. The results showed sulfonic group and carboxylic acid group were successfully introduced into copolymer and the dispersant，and the GPC showed the weight average molecular weight of about160 00, polydispersity was 3.41.
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  Synthesis and Application of Polymeric Yellowing Inhibitor Based on Naphthalimide Fluorescent Brightening Agent

  . 2012, 43(23): 19-0.

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  Naphthalimide fluorescent brightening agent(FBA) was synthesized from 4-bromo-1,8-naphthalic anhydride and ethanolamine via amidation, then joining ethoxy electron-donating group into 4-bit of naphthalene ring. With cyanuric chloride as the crosslinking monomer, a new yellowing inhibitor for high-yield pulp was synthesized through joining the ultraviolet absorber(UVA) 2,4-dihydroxy-benzophenone and naphthalimide fluorescent brightener in the same molecule. Then a water-soluble yellowing inhibitor polymer was obtained by copolymerization between it with acrylamide. The molecular structures were characterized by IR spectra；optical properties were measureed by UV spectra and fluorescence spectra. Coating the three prepared additives according to a certain concentration on the surface of paper, their yellowing inhibition effect were studied by UV accelerated yellowing experiments. The results show that: When the three additives use the Optimal dosage, after 26h UV accelerated aging, the yellowing inhibition effect of them followed the order : yellowing inhibitor polymer > yellowing inhibitor monomer > naphthalimide FBA.
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  Study on the Graphene Preparation on Cu–Ni Alloy Substrate by Chemical Vapor Deposition.

  Xing-Ao LI

  . 2012, 43(23): 20-0.

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  The Cu–Ni alloy thin films with different ratio of Cu and Ni were prepared by double targets magnetron sputtering method. The samples were characterized by energy dispersive analysis of X-rays (EDAX). The ratio of Cu and Ni was accurately determined. Three graphene samples were fabricated with benzene as carbon source on the same kind of Cu–Ni alloy substrates at variable temperature of 800℃, 600℃ and 400℃ by chemical vapor deposition method to study the impact of temperature on the growth of graphene. Three graphene samples were produced on three different Cu–Ni alloy substrates at 400℃ to study the impact of different ratio of the substrates on the growth of graphene.
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  Preparation and phosphorus recovery performance of calcium silicate hydrate

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  . 2012, 43(23): 21-0.

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  Study on the Preparation of a Novel Embedded Spherical Cellulose Adsorbent

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  . 2012, 43(23): 22-0.

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  The embedded spherical cellulose adsorbent (ESCA) was prepared by the thermal solution-gel transition technique using masson pine kraft pulp cellulose as materials, and the adsorption of berberine hydrochloride was studied. Black wattle extract was embedded in cellulose matrix in cellulose regeneration process. The results showed that, the embedded spherical cellulose adsorbent with 98.26% of encapsulation efficiency for black wattle extract could be obtained under the optimal conditions (1.00% of black wattle extract dosage, 6.67% of calcium carbonate dosage, 3.33% of gelatin dosage and 0.50% of sodium oleate dosage). The moisture content of ESCA was 73.2%, and the specific surface area was 436.2m2/g. The adsorption percentage and the equilibrium adsorption capacity of berberine hydrochloride by ESCA could reach 95.28% and 23.82mg/g, respectively, under such conditions as 200mg/L of berberine hydrochloride concentration, 4 of the solution pH, 3.0h of the adsorption time and 30℃ of the adsorption temperature.
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  The impact on the stab resistance of complex Shear thickening fluids treated nonwovens

  ; ;

  . 2012, 43(23): 23-0.

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  By introducing the idea of "complex match", shear thickening fluid (STF) was prepared in several kinds and the different kinds of STF were compound with ultra high molecular weight polyethylene non-woven fabrics. The pattern and performance of the compound fabric were characterized by scanning electron microscopy (SEM) and static stab resistant experiment. The paper mainly studied the impact in stab-resistant performance of the non-woven fabrics which were treated by complex STF with different molecular weight (PEG200, PEG600). It can be found that the performance of treated fabric with different molecular weight dispersed media is better than the one with single molecular weight. It also shows that the complex STF could improve the performance of stab resistance to a certain extent. The penetration strength is enhanced by 7.13% with the same unit mass in this paper.
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  Effects of hot rolling processes on microstructure and properties of 3.2%Si non-oriented silicon steel by thin slab cast rolling

  Hai-Tao LIU

  . 2012, 43(23): 24-0.

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  It was investigated that the effects of thin slab cast rolling (TSCR) hot rolling processes on microstructural, textural evolution and magnetic properties of 3.2%Si-0.7%Al non-oriented silicon steel. The results show that much larger hot rolling deformed microstructure and much stronger {001}<110> texture could be obtained by increasing the soaking and hot rolling temperatures, which had good heritable effects on subsequent microstructural, textural evolution and magnetic properties. The final sheets fabricated at higher soaking and hot rolling temperatures possessed much larger recrystallization grains, relatively stronger λ-fiber and weaker γ-fiber recrystallization texture and higher magnetic induction.
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  Discoloration performance of Wooden-base photochromic functional materials

  guo-liang li

  . 2012, 43(23): 25-0.

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  Photochromic materials and wood were composited by the sol-gel using polyvinyl alcohol as carriers to prepare Wooden-base photochromic functional materials under the ultraviolet irradiation(UV-irradiation). Chromaticity indexes and visual effects before and after the UV-irradiation were compared to disscuss the effects of UV-irradiation on the Color difference indexes of wooden-base photochromic functional materials. It turned out that photosensitive color effects of the material surface were remarkable and color difference value increased significantly after the UV-irradiation.
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  Interactions between Ionic Surfactants and Hydrophobically Associating Polyacrylamide in Aqueous Solution

  Chen WANG

  . 2012, 43(23): 26-0.

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  Hydrophobically associating polyacrylamide (UHAPAM) was prepared by the reaction of octadecyl acrylate (ODA), acrylamide (AM) and 2-acrylamido -2- methyl propane sulfonic acid (AMPS) through ultrasonic assisted polymerization. The dynamic rheology property of UHAPAM and interactions between ionic surfactants (odium dodecyl sulfate (SDS) and hexadecyl trimethyl ammonium bromide (CTAB)) and UHAPAM were studied by dynamic rheology, power-law model, static/dynamic light scattering and fluorometry The results showed that the critical association concentration (CAC) of UHAPAM aqueous solution was determined as approximately 0.27% and when the UHAPAM solution concentration was higher than CAC, SDS was adverse to inter-molecular association, which led to reduced apparent viscosity; CTAB improved the hydrophobically associating properties on the contrary, which significantly resulted in increased apparent viscosity, but as CTAB continued to increase, the thickening effect deteriorated. Both the surfactants reduced thixotropy of UHAPAM solution. At the same time, the shape factor(/)increased all the time in SDS-UHAPAM system as SDS concentration increased, which reflected the relative stretch of the polymer chains; but it appeared a minimum value in CTAB-UHAPAM system with CTAB concentration increasing, which reflected the polymer chain transformed from curl to stretch..Along with UHAPAM concentration increasing, aggregation number (N) of SDS micelles increased after first reducing, and that of CTAB micelles increased continuously.
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  Decomposition Kinetics and Process Experiments on Dolomite

  ;Gao Jiao Cheng

  . 2012, 43(23): 27-0.

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  Preparation of High Concentration and Low Viscosity Polyacrylate Microemulsion by keto- hydrazine crosslinking and Experimental Study on its Performance

  Juan ZHANGYi-ding SHEN;;

  . 2012, 43(23): 28-0.

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  High concentration polyacrylate microemulsion were prepared by using seed polymerization, in which the acrylic monomers was the polymerisable monomers. The effects that influence viscosity and particle size of polyacrylate emulsion including emulsifier content ,initiator content and the soft monomer to hard monomer were diacussed. In addition, using IR, TEM, particle size analyzer to characterize the copolymer. The results shows that,with the increas of dosage emulsifier, emulsion viscosity increase and decreasing the particle size gradually；with the increase of the dosage of initiator emulsion particle size increases first, then decreases, while with the increase of the dosage of initiator emulsion viscosity decreases increased first,then decreases.with the increase of the proportion of the soft monomer to hard monomer, emulsion viscosity increases gradually, and the influence of emulsion particle size is not clear.and when the polyacrylate emulsion PH range of 7.5～9.0, the polyacrylate emulsion has good stability.
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  Effect of dispersion of conductive short-fiber on its radar absorbing property

  Hong-Jie ZHAO ;;

  . 2012, 43(23): 29-0.

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  Effect of dispersion of conductive short-fiber on its radar absorbing property is studied by simulations and experiments. The simulating results show that electromagnetic loss with the electric field polarizing in parallel with the fiber is more powerful than that perpendicularly to it for a single fiber. Moreover, for parallel fibers, the loss decreases remarkably as the interval decreases, i.e., the degree of aggregation increases. The composite laminated plates derived from different dispersive processing of carbon fiber are prepared using mould pressing forming and the reflectivities are measured. The results show that the radar absorbing performance for the plate derived from homogeneously dispersive fiber is better and that from inhomogeneously dispersive one is worse.
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  Modification on artificial graphite anode material by coating with organic pyrolytic carbon

  ;Hai-lei Zhao ;;

  . 2012, 43(23): 30-0.

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  Organic pyrolytic carbon-coated artificial graphite anode material with a core-shell structure was prepared via a sol-gel and pyrolysis route. The effects of coating amounts and species of carbon resource on the lattice structure, the particle morphology and the electrochemical performance of the modified artificial graphite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), constant current charge-discharge and cyclic voltammogram (CV) tests. The electrochemical measurements reveal that the sample coated with 5 wt.% PVDF exhibits a stable specific capacity of 360 mAhg-1, a higher initial coulombic efficiency of 88.5%, excellent rate-capability and good cycling stability. This may be mainly attributed to the complete formation and the proper thickness of amorphous carbon film on the surface of graphite particles. The isotropic structure characteristics of amorphous carbon increase the diffusion channels of lithium ions and thus facilitate the electrode reaction process.
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  Mechanisms of extracting lithium by spinel-type LiMn2O4 with acid elution

  Jun-Qi ZHOU;

  . 2012, 43(23): 31-0.

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  LiMn2O4 precursor was prepared by high temperature solid-state method. Chemical analysis, X-ray powder diffraction analysis, thermal analysis and infrared analysis of adsorbed and eluted products were characterized, and the corresponding relationships between lithium exchange capacity and manganese dissolved loss were investigated. The chemical compositions of adsorbed and eluted products may be expressed by LixMn2O4 (0≤x≤1), which was proposed and verified for the first time, and their structures remain spinel-type. Redox reaction mechanisms of the adsorption and elution process were described in detail when hydrochloric acid was eluent, and more prefect chemical reaction equations were given. The experimental results showed that elution and adsorption process were not thoroughly and completely result in adsorption capacity of ionic sieve was low compared with saturated adsorption, and the disproportionation of Mn3+ leaded to manganese dissolved loss. Furthermore the guiding suggestions for the further researches on extracting lithium with ionic sieve were proposed.
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  Preparation and magnetic properities of airflow crashed amorphous Fe78Si9B13 magnetic powder core

  ;Rui GUOYOU Jun Hua;

  . 2012, 43(23): 32-0.

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  The amorphous magnetic powder cores were fabricated by the airflow crashed Fe78Si9B13 amorphous powder using power metallurgical technology. Differential thermal analyzer, X-ray diffractometer, B-H analyzer were used to measure the thermodynamic parameters, internal microstructure and magnetic properties for samples. Effects of insulating compound content and annealing temperature on the performance of magnetic powder cores were investigated. The results indicate that: Eddy current loss can be reduced by increasing the insulating compound content, but excessive insulating compound can reduce the magnetic permeability and quality factor. The stress relief annealing could promote permealibility and quality factor ,reduce the magnetic loss. Over annealing temperature could deteriorate magnetic properties due to crystallization of amorphous power, and the optimum annealing temperature is 400℃.
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  Preparation and characterization of three-dimensional porous β-tricalcium phosphate scaffolds with controlled porous architecture

  Xuan WEI;; Jian-Dong YE

  . 2012, 43(23): 33-0.

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  Tissue engineering scaffolds for bone repair have high requirement of interconnectivity and pore geometry. Controllable preparation of pore structure is the key to work out this problem. The objective of this work was to prepare three-dimensional porous inorganic scaffolds with controlled pore structure. The β-tricalcium phosphate slurry with high solid content was poured into the polymer porous moulds with different pore structure, which were fabricated by rapid prototyping technique, then the β-tricalcium phosphate three-dimensional porous scaffolds were obtained by in situ consolidation of gel-casting. The pore structure of scaffolds was characterized by micro-computed tomography (micro-CT), and the phase composition, morphology images and compressive strength of the porous scaffolds were tested. The scaffolds using polymer porous models have connective macro-pores structures. The compressive strength and macro-pores porosity of scaffolds were more than 2MPa and more than 50%. The results indicate this method is an effective way to control the pore structure and pore size of β-tricalcium phosphate tissue engineering scaffold with full interconnectivity.
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  Research of optimization of thickness ratio of silicon to aluminum in the process of aluminum induced crystallization

  . 2012, 43(23): 34-0.

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  Corning glass Eagle 2000 was used as substrate to prepare glass/amorphous/silicate/aluminum stacks of different thickness ratio of silicon to aluminum by magnetron-sputtering. The stacks were annealed at 450 oC for selected time in Ar atmosphere and polycrystalline silicon film was achieved by aluminum-induced crystallization. Raman spectra and ultraviolet reflectance spectra were used to measure the crystalline quality of polycrystalline silicon. The crystalline quality is greatly influenced by the thickness ratio. The optimum thickness ratio of silicon to aluminum is 5:1, which is inferred by the crystalline quality.
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  The mechanical properties of diamond particles reinforced aluminum matrix composites

  Jian-Hua Wu;;;;

  . 2012, 43(23): 35-0.

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  Diamond particles reinforced aluminum matrix composites were fabricated by squeeze casting method. The effect of diamond size on the microstructure, mechanical property and fracture morphology of composite were investigated. The results show that the mechanical properties of Al/diamond composite gradually increased with the decrease of particle size. Under diamond particle size of 400/500 mesh, the tensile strength of Al/diamond composite is 145MPa, compressive strength of 1020MPa, along with bending strength of 310MPa.
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  The Research Progress of Graphene Synthesis Method

  JIANG LI LI

  . 2012, 43(23): 36-0.

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  Graphene has attracted much attention in fields such as physics, chemistry, and materials science, because of its unique properties and potential applications.. This is a review of synthesis of graphene using different preparation methods, such as epitaxial growth, chemical vapor deposition, micromechanical exfoliation and chemical reduction of graphene oxide. The further prospects and improvement of strategies for synthesis of graphene have also been discussed.