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.
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.
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.
The synthesis of Ti3AlC2/TiB2 composites was studied by in-situ spark plasma sintering with different volume content of TiB2. Results indicated the bulk Ti3AlC2/TiB2 was fabricated by SPS, which soaked for 8 min under...
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The synthesis of Ti3AlC2/TiB2 composites was studied by in-situ spark plasma sintering with different volume content of TiB2. Results indicated the bulk Ti3AlC2/TiB2 was fabricated by SPS, which soaked for 8 min under a pressure of 30 MPa at 1250°C. The properties of composites was great increased with the addition of TiB2;the Vicker's hardness increased with addition of TiB2 content, the maximum value is 10.4 GPa. The maximum flexural strength and fracture toughness reached maximum value, which were 696 MPa and 6.6 MPa·m1/2 when the volume content of TiB2 was 10%.
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.
Based on the electrochemical model, a simulation model has been developed with Matlab/Simulink. Steady-state analysis has been developed to evaluate how the temperature affect the voltage and output power of the fuel ...
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Based on the electrochemical model, a simulation model has been developed with Matlab/Simulink. Steady-state analysis has been developed to evaluate how the temperature affect the voltage and output power of the fuel cell. Dynamic analysis focus on the dynamic response of the output voltage, the output power, the consumed power, the efficiency and the internal resistance of a single PEMFC when the current of a PEMFC increase or decrease transiently. This simulation model also adapted to the simulation of PEMFC stack. The study is helpful for the optimization and control of PEMFC.
Buffer material plays an important role in the hypervelocity launching experiments. By using numerical calculations, the influence of TPX buffer material's thickness on high impedance tantalum flier plate's ve...
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Buffer material plays an important role in the hypervelocity launching experiments. By using numerical calculations, the influence of TPX buffer material's thickness on high impedance tantalum flier plate's velocity is analyzed, and the optimal thickness of buffer material is also evaluated. For thickness of 0.3 mm and 0.5 mm tantalum flier plate, the relative error of tantalum flier plate's center velocity is about 5%-6% at different thicknesses of the TPX buffer materials. In order to compare the influence of different buffer materials on tantalum flier plate's velocity, the two-dimensional results of tantalum flier plate's center velocity and pressure histories are calculated at the same thickness of TPX and Lexan buffer.
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.
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