High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope...
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High alumina cement/graphite conductive composites were prepared by mold pressing at room temperature. Electrical conductivity was measured and the composite morphology was investigated by scanning electron microscope (SEM). The heat stability and water content of conductive composites were also studied under proton exchange membrane fuel cell (PEMFC) operating temperature. The test results show that the percolation phenomenon is exist in the composite bipolar plate, the threshold value is 8%-10%;moreover, the composite bipolar plate has excellent heat stability and self- humidification.
Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion...
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Metal-N-H is considered as one of the most-potential hydrogen storage materials as on-board applications for its high gravimetric hydrogen content at relatively gentle condition. The research development of conversion from Li-N-H to Mg-N-H is presented, two types of possible reaction mechanisms are discussed and three amide-synthesizing methods are introduced. The unsolved problems of development and application of the Metal-N-H system are also generalized.
Different humidification of proton exchange membrane fuel cells were investigated using PEM module of fluent software. Influence of different humidification degrees on performance of PEM fuel cell was studied, especia...
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Different humidification of proton exchange membrane fuel cells were investigated using PEM module of fluent software. Influence of different humidification degrees on performance of PEM fuel cell was studied, especially influence of Concentration polarization on PEM fuel cell performance was discussed in the high current density. 0%, 50% and 100% humidification of 80°C cathode gas were contrasted. The results showed that 100% humidification was better at low current density, while at high current density, 50% humidification was better. The relation between the performance of fuel cell and the distribution of O2 and H2O mol concentration on the interface between cathode diffusion layer and catalyst layer were analyzed. The results showed only partial regions of catalyst layer exist concentration polarization. Taking properly humidification can obtain higher performance in different current density.
Aluminum borate whisker with TiB2 as borate source was prepared in this paper. The phase transformation process and whisker growth mechanism were analyzed. The results indicate that TiB2 is oxidized by active [O] rele...
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Aluminum borate whisker with TiB2 as borate source was prepared in this paper. The phase transformation process and whisker growth mechanism were analyzed. The results indicate that TiB2 is oxidized by active [O] released from the decomposition of (NH4)2SO4. B2O3 released from TiB2 oxidation provide borate source for whisker growing. Al/B ratio has influence on whisker morphology. Surplus B2O3 is needed during aluminum borate whisker growth because liquid B2O3 is a medium to transport Al2O3 to the tiny whisker nearby.
High-energy ball mill method was used to treat the stainless steel powder;the effects of treat parameters (ball-raw materials rate, treatment time) on the microstructure and phase composite were studied. X- ray diffra...
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High-energy ball mill method was used to treat the stainless steel powder;the effects of treat parameters (ball-raw materials rate, treatment time) on the microstructure and phase composite were studied. X- ray diffraction, SEM and the BET method were used to evaluate the microstructure of treated samples. The results showed that with increasing in ball mill time, the particle size of stainless steel powder decreases obviously;surface features of powder were changed significantly. X-ray diffraction calculation results showed that the particle size of stainless steel powder have been 28 nm after 120 h ball mill treatment, the BET analysis results agree with the X-ray diffraction calculation results.
Cobalt-rich filled skutterudite compounds CeyFexCo4-xSb12 (y=0-0.42) are synthesized using the melting-diffusion method. The structure and thermoelectric properties of the compounds are investigated. Results indicate ...
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Cobalt-rich filled skutterudite compounds CeyFexCo4-xSb12 (y=0-0.42) are synthesized using the melting-diffusion method. The structure and thermoelectric properties of the compounds are investigated. Results indicate that the lattice constants increase linearly with the Ce filling fraction. Hall coefficient is positive. Hole concentration and electrical conductivity decreased as the Ce filling fraction increases. Seebeck coefficient increase with the Ce filling fraction. The lattice thermal conductivity reached the minimum value when the Ce filling fraction was about 0.29, indicating that the effect of Ce rattling on phonon scattering is the strongest as Sb-dodecahedron partial voids are filled by Ce. A maximum ZT value of 0.65 is obtained for Ce0.29Fe1.41Co2.59Sb12.32 at 725 K.
Fuel cell stack breathing control system is important to avoid degradation of the proton exchange membrane fuel cell (PEMFC) stack voltage, and to maintain high efficiency and long stack life. This paper propose a new...
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Fuel cell stack breathing control system is important to avoid degradation of the proton exchange membrane fuel cell (PEMFC) stack voltage, and to maintain high efficiency and long stack life. This paper propose a new control technique for fuel cell stack breathing control system based on hybrid model, which combines space state equation with neural network black-box model. PEMFC stack process is represented with space state equation, the output of PEMFC stack voltage is modeled with neural network which consists of an input layer, a hidden layer and an output layer. Then adaptive neural controller is designed to control fuel cell breathing system based on hybrid model. The simulation results demonstrate that the proposed hybrid model and the adaptive neural controller have good performance
Sulfonated poly (ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) were prepared with H2SO4 as sulfonating agent. It was found that the SPEEK membranes have promising mechanical strength a...
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Sulfonated poly (ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) were prepared with H2SO4 as sulfonating agent. It was found that the SPEEK membranes have promising mechanical strength and perfect proton conductivity. For 86% DS, proton conductivity was 5.5 × 10-3 S/cm;and the max mechanical strength was 45.9 MPa.
Gas diffusion layer, a component of proton exchange membrane fuel cell, plays an important role in supporting the catalyst layer, conducting electrons, gas diffusion and water removal. A micro-porous layer composed of...
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Gas diffusion layer, a component of proton exchange membrane fuel cell, plays an important role in supporting the catalyst layer, conducting electrons, gas diffusion and water removal. A micro-porous layer composed of PTFE and carbon powder coated on the hydrophobic carbon paper can optimize the water management and performance of the fuel cell. Compare to micro-porous layer with different gas permeability (300 s, 600 s, 1200 s, 2000 s), the performance, stability and water management with the micro-porous layer is 1 200 s gas permeability is the best (the result is tested by Gurly4118 Air Permeability Tester).
The relations between composition, structure, chemical bond and property of TiC, FeAl, Fe3Al and composites of TiC/Fe-Al series were studied by using density function theory and discrete variation method (DFT-DVM). Th...
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The relations between composition, structure, chemical bond and property of TiC, FeAl, Fe3Al and composites of TiC/Fe-Al series were studied by using density function theory and discrete variation method (DFT-DVM). There were strong ionic and covalent interacts among the interfaces of TiC/FeAl and TiC/Fe3Al composites. The ionic bonds became weak, and the covalent was strong gradually from the single phase of TIC, FeAl or Fe3Al, to composite TiC/FeAl or TiC/Fe3Al. The interaction of the orbitals and the covalent bond of TiC/Fe3Al were stronger than those of TiC/FeAl. The results were consistent with the experiment of bending strength when the content of Al increases in the TiC/Fe-Al system.
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