A new compound,[Co（dien）2]（dienH3）（H3O）7[P2Mo5O23]2·14H2O, has been hydrothermallly synthesized by using Na2MoO4,CoCl2, H3PO4 and dien, and structurally characterized by elemental analysis, X-ray powder dif...
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A new compound,[Co（dien）2]（dienH3）（H3O）7[P2Mo5O23]2·14H2O, has been hydrothermallly synthesized by using Na2MoO4,CoCl2, H3PO4 and dien, and structurally characterized by elemental analysis, X-ray powder diffraction analysis, SEM, IR and TG analysis. The results show that the compound is composed of a polyanion [P2Mo5O23]2^12, complex [Co（dien）2]^2＋ cation, protonated [dienH3]^3＋ , and forteen crystallization water molecule.
WC-10Co nanocrystalline composite powders prepared by spray pyrogenation-continuous reduction and carburization technology were consolidated by vacuum sintering plus hot isostatic pressing （HIP）. Influences of carbo...
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WC-10Co nanocrystalline composite powders prepared by spray pyrogenation-continuous reduction and carburization technology were consolidated by vacuum sintering plus hot isostatic pressing （HIP）. Influences of carbon content on properties and microstructure of ultrafine WC-10Co cemented carbide were investigated. The results show that the relative density of the ultrafine WC-10Co cemented carbides can reach 99.72%, and the transverse rupture strength （TRS） was higher than 3 890 MPa, Rockwell A hardness （HRA） was higher than 92.5, the average grain size was less than 460 nm, when carbon content in nanocrystalline composite powder was 5.54wt% and the ball-milled time was 48 hours, ultrafine WC-10Co cemented carbide with excellent properties and homogeneous microstructure was obtained.
A ternary-layered carbide Ti2AlC material could be synthesized by spark plasma sintering（SPS） technology using elemental powder mixture of Ti, Al and active carbon. By means of XRD and SEM, phases were identified an...
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A ternary-layered carbide Ti2AlC material could be synthesized by spark plasma sintering（SPS） technology using elemental powder mixture of Ti, Al and active carbon. By means of XRD and SEM, phases were identified and microscopically evaluated. The experimental results show that the main phase in the product was fully crystallized Ti2AlC with small particle size when sintered at 1200℃. The synthesis temperature of SPS was 200-400℃ lower than that of hot pressing （HP） or hot isostatic pressing （HIP）. Through thermodynamics calculations, the mechanism of Ti2AlC was studied by calculating changes of Gibbs free energy of reactions.
Serial material model （Dilute model）and Limited Units （LU）method were employed to analyze the performance of binary piezo-composite *** reckoned electric potential deployments illustrated difference while the part...
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Serial material model （Dilute model）and Limited Units （LU）method were employed to analyze the performance of binary piezo-composite *** reckoned electric potential deployments illustrated difference while the particles were *** piezoelectricities were also calculated according to the model,and furthermore comparation suggested that small particles living in the tolerance improve the piezoelectricity of *** coinciding with analyses were processed simultaneously. Ceramics were milled for different time in order to control the concentration of particle *** results showed that the filled particles enhanced the piezoelectricity of binary piezo-composite system efficiently whereas too many chips deteriorated the performance of piezo-composites.
Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate （TEOS） in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR,TG-DSC...
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Nafion/Silicon oxide composite membranes were produced via in situ sol-gel reaction of tetraethylorthosilicate （TEOS） in Nafion membranes. The physicochemical properties of the membranes were studied by FT-IR,TG-DSC and tensile strength. The results show that the silicon oxide is compatible with the Nation membrane and the thermo stability of Nation/Silicon oxide composite membrane is higher than that of Nation membrane. Furthermore, the tensile strength of Nation/Silicon oxide composite membrane is similar to that of the Nation membrane. The proton conductivity of Nation/Silicon oxide composite membrane is higher than that of Nation membrane. When the Nation/Silicon oxide composite membrane was employed as an electrolyte in H2/O2 PEMFC, a higher current density value （1 000 mA/cm^2 at 0.38 V） than that of the Nafion1135 membrane （100 mA/cm^2 at 0.04 V） was obtained at 110 ℃.
Grid computing is an active field in high-availability computing. This paper focuses on the numerical calculation of two-dimensional frequency selective surface using the finite difference time domain (FDTD) method on...
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Grid computing is an active field in high-availability computing. This paper focuses on the numerical calculation of two-dimensional frequency selective surface using the finite difference time domain (FDTD) method on grid-enabled cluster. The result of experiment shows that the evaluation via the parallel FDTD is in good agreement with the result obtained via the traditional FDTD method. The parallel FDTD algorithm is correct and reasonable, which can be extended to other periodic structure and finite exciting sources.
A novel method was used to fabricate AIN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate...
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A novel method was used to fabricate AIN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate; secondly, AIN coating was formed through the in-situ reaction of Al with the sprayed BN. The reaction was investigated by thermogravimetric-differential thermal analysis (TG-DTA), and the phase composition in the synthetic process was characterized by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) was used to observe the morphology, and electron probe microanalysis (EPMA) was used to observe the distribution of the elements. The experimental results show that the AIN coating is dense and bonded with graphite tightly.
Ti2AlC bulk material was synthesized by hot pressing of mixture powders of TiC, Ti, Al and active carbon. The phase compositions of resultant product at different temperature were detected by X-ray diffractometer. The...
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Ti2AlC bulk material was synthesized by hot pressing of mixture powders of TiC, Ti, Al and active carbon. The phase compositions of resultant product at different temperature were detected by X-ray diffractometer. The microstructures of the samples were observed by SEM. Finally, the mechanical properties and thermal properties of the sample at 1400 ℃ were measured. The results show that high purity Ti2AlC material with little Ti3AlC2 can be synthesized by hot pressing 0.5TiC/1.5Ti/1.0Al/0.5C at 1 400 ℃. Ti2AlC exhibits high mechanical properties and metallic electrical properties. Its fracture toughness is 7.0 MPa·m1/2, its flexural strength is 384 MPa at room temperature, and its electrical conductivity is 2.56×106 Ω1·m-1 at room temperature.
Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calcu...
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Combustion synthesis of titanium diboride(TiB2) from titanium(Ti) and boron(B) powders was studied by theoretical calculation and experimental analysis. In high temperature range or in low temperature range, the calculated activation energies are 140KJ/mol or 355KJ/mol respectively, which is described by a change from dissolution-precipitation controlled process to diffusion-controlled process. With the increase of particle size of the raw materials, combustion temperature and propagating rate will both reduce. The propagating rate decreases with the addition of diluents. Further increase of diluents may result in a stop of the combustion wave halfway or even a failure of ignition.
The valence electronic states at the model tunneling junction interface MgO∕Fe(001) system were systematically studied by comparing the spin-resolved photoemission spectroscopy of clean Fe(001) and MgO covered MgO∕F...
The valence electronic states at the model tunneling junction interface MgO∕Fe(001) system were systematically studied by comparing the spin-resolved photoemission spectroscopy of clean Fe(001) and MgO covered MgO∕Fe(001) surfaces using linearly p-polarized light. For the clean Fe(001) film on GaAs(001), five distinct features including bulk and surface-related transitions are found. The bulk and surface-state transitions are well-accounted for by the direct transition model based on the calculated energy band structure of bcc bulk Fe(001). The previously observed minority feature at a binding energy EB=−1.3eV is reinterpreted as a surface roughness associated transition. Upon the MgO adsorption on Fe(001), the surface-state transitions at EB=−0.3eV below Fermi energy EF appearing in both the majority and minority spin spectra at low photon energy (18eV to 35eV) were quenched. This is also the first direct experimental evidence of a minority spin surface state located just below the Fermi energy as predicted previously. The bulk states at the MgO∕Fe(001) interface exhibit a layer-dependent modification, i.e., the bulk states in the deeper Fe layer(s) remain unaffected, while the states of Δ5↓ band symmetry in the Fe layer(s) closest to the MgO∕Fe(001) interface are strongly modified, in contrast to the states of Δ1↑ symmetry. As a consequence of this interface effect, the “partial spin polarization” at the Fermi level changes sign from negative to positive values as seen in the spin asymmetry spectra at photon energies of 40eV and 60eV. The origin of this spin- and symmetry-dependent modification observed at MgO∕Fe(001) interfaces is discussed.
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