The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is inves...
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The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is investigated in detail. The results show that fuel cell with a 2 mm channel width can realize the long time operation in a closed-ended situation. The voltage of the 1mm width cell can drop from 0.7 V to 0.5 V in 3 min, while the 2 mm width cell can last for more than 53 min. Moreover, the temperature has a significant effect on the performance, the voltage of the 1 mm width cell can drop from 0.69 V to 0.5 V in less than 1.7 min. The resistance of the cell is increasing with the temperature, but the amplitude is smaller in high temperature.
Aluminum nitride whiskers were synthesized by nitridation of commercial aluminum powder at 1623K in a nitrogen atmosphere. The starting materials consisted of aluminum and carbon black. The carbon acted as a barrier b...
Aluminum nitride whiskers were synthesized by nitridation of commercial aluminum powder at 1623K in a nitrogen atmosphere. The starting materials consisted of aluminum and carbon black. The carbon acted as a barrier between aluminum powders during nitridation and was removed by heating in air at 923K. The whiskers were about 0.5-1μm in diameter and 10-20μm in length. The droplets at the whisker tips showed that the whiskers grew via a vapor-liquid-solid mechanism. The morphologies of the whiskers were studied by means of SEM and TEM. The formation of the whiskers depended on the processing conditions.
In the present study electronic structures of the interface between SBT and transition metal including Au, Ag, Cu, Ni, Pt were studied by employing DV-Xα method. The calculations were performed on cluster models of t...
In the present study electronic structures of the interface between SBT and transition metal including Au, Ag, Cu, Ni, Pt were studied by employing DV-Xα method. The calculations were performed on cluster models of the interface which were SrTa8O36-M2 (M=Au, Ag, Cu, Ni, Pt, and Bi). The calculations results including Fermi level, bond order, atomic charge distribution shown that there existed significant hybridization between metal d states and the O2p–Ta3d states. The Fermi levels of the metals located in the gap of SBT and metal-induced states, and the position of the Fermi levels did not change greatly due to the different transition metals. The charge of Sr and the transition metal atom transferred to oxygen atom, so that the bonding between Sr (or metal atom) and O was almost ionic bonding. The interactions between transition metal and SBT mainly came from the Coulomb interaction.
The new type of the hierarchically structured porous solid-acid catalysts described in this presentation possess a remarkable pore system,encompassing well-defined macrochannels,interconnected mesopores,intracrystalli...
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The new type of the hierarchically structured porous solid-acid catalysts described in this presentation possess a remarkable pore system,encompassing well-defined macrochannels,interconnected mesopores,intracrystalline mesopores,and tunable zeolite(ZMS-5,Beta,…)*** hierarchical micro-meso-macroporous zeolitic catalysts with improved stability have been synthesized via a quasi solid state chemical crystallization ***,the catalyst
The n-type nonstoichiometric Pb0.55Te0.45materials were prepared by melting and quenching combined with a subsequent high pressure high temperature (HPHT) treatment. After adequately annealed at 623 K in the argon atm...
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The Bypass-Electrode GMAW method was introduced. The Siemens's S7-200PLC was used to be the core of the control system. Also the high-speed welding control system was designed and realized. The welding program was...
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The Bypass-Electrode GMAW method was introduced. The Siemens's S7-200PLC was used to be the core of the control system. Also the high-speed welding control system was designed and realized. The welding program was written by STEP7-Micro/WIN language. Sequential control, real-time data acquisition and processing signal were realized by controlling program, displaying by touch screen. The welding parameters of flat surfacing and flat lap welding were ensured with experiments. The results show that the welding equipment has high precision of welding and stable performance characteristics and can realize more stable Bypass-Electrode GMAW process. The weld pool is beautiful and little splash.
The CaF_(2)-4LiF additive was added into SrTiO_(3)ceramics in order to decrease the sintering temperature for compact pulse power *** crystalline structure,microstructure and energy storage performance of sintered cer...
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The CaF_(2)-4LiF additive was added into SrTiO_(3)ceramics in order to decrease the sintering temperature for compact pulse power *** crystalline structure,microstructure and energy storage performance of sintered ceramics were *** CaF_(2)-4LiF additive to SrTiO_(3)ceramics contributes to a notably enhancement of the energy storage *** great enhancement in energy storage density occurred due to the notable increase in breakdown strength and the refinement of *** 2 at%additive,the samples exhibited an average breakdown strength of 31.8kV/mm,and an energy storage density of 1.212 J/cm^(3)which is about 1.4 times higher than pure SrTiO_(3).
Ceramic sintering in microwave field is a new ceramic processing method. In present paper, we detected the microstructures and boundary segregation of BaTiO3 ceramics which were sintered in microwave field. Scanning e...
Ceramic sintering in microwave field is a new ceramic processing method. In present paper, we detected the microstructures and boundary segregation of BaTiO3 ceramics which were sintered in microwave field. Scanning electron microscopy(SEM), and transmission electron microscopy(TEM), and chemical analysis methods were employed to detect the microstructure of BaTiO3, element distribution near the boundary of BaTiO3 ceramic. The results shown growth of grain of the ceramic was influenced by impurities such as acceptor, benefactor et al, and the element distribution near the grain boundary of BaTiO3 sintered in microwave field were different with that sintered in conventional method. The boundary segregations of BaTiO3 sintered in microwave field were not obvious as compared to the conventional method because the diffusion was enhanced due to the microwave field.
Highly oriented titanate nanotube (TNT) film was successfully synthesized by a simple electrophoretic deposition (EPD) method without any hard templates and surfactants. This oriented films adequately utilized the exc...
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