The physical performances of alumina cement-based composite fabricated by vibratory compaction by using alumina cement as gelling agent and graphite as conductive filler were studied in this paper. The change trends o...
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The physical performances of alumina cement-based composite fabricated by vibratory compaction by using alumina cement as gelling agent and graphite as conductive filler were studied in this paper. The change trends of volume resistivity, compressive strength and apparent density of these composite with graphite content were obtained. And the percolation theory was applied to explain the electrical mechanism of these composites. The experimental results showed that the volume resistivity of these composites varied in 106-102Ω·cm, which can be used as antistatic, electric engineering and electro thermal materials.
This paper introduced the preparation of zinc oxide whiskers with different morphology. The result of SEM showed that one was multi-needle whiskers, the other was hexagonal rods. The result of the XRD indicated that t...
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This paper introduced the preparation of zinc oxide whiskers with different morphology. The result of SEM showed that one was multi-needle whiskers, the other was hexagonal rods. The result of the XRD indicated that the production structure was wurtzite, which was mixed with hydrocarbon. The results of SEM indicated that the mixture had an important effect on the the morphology of the whiskers.
In this paper, fuel cell testing process was summarized. From the calibration of test station, parameters record and testing process, we analyzed the process and experiment condition which must be standardized in orde...
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In this paper, fuel cell testing process was summarized. From the calibration of test station, parameters record and testing process, we analyzed the process and experiment condition which must be standardized in order to obtain repeatable, reproducible and scaleable parameters of the performance and durability. Due to the process of fuel cell working is a complicated balanceable system including mass transfer, electrochemical reaction and thermo transfer etc, the fuel cell testing is consequentially a rigorous testing process. Every tache of it was restricted by the other, and every restricted factor will maybe influence the test results. So, a exhaustive testing protocol must be established.
Nafion/PTFE composite membranes based on different ePTFE were prepared in this work. Porous PTFE was perfectly impregnated by Nafion resin. The differences of mechanical properties such as tensile strengths and dimens...
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Nafion/PTFE composite membranes based on different ePTFE were prepared in this work. Porous PTFE was perfectly impregnated by Nafion resin. The differences of mechanical properties such as tensile strengths and dimensional changes were analyzed in this paper. From electrochemical and single cell tests, the optimum thickness of porous PTFE for the composite membrane is 15 μm. The performance of the composite membrane based on the 15 μm-thick porous PTFE was 0.664 V at 600 mA/cm2, which was higher than Nafion111 membrane at the same conditions.
The gas diffusion layer (GDL) durability of proton exchange membrane fuel cell (PEMFC) was reviewed. The testing methods and the characterization of the durability of GDL were summarized in this paper. The degradation...
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The gas diffusion layer (GDL) durability of proton exchange membrane fuel cell (PEMFC) was reviewed. The testing methods and the characterization of the durability of GDL were summarized in this paper. The degradation mechanisms of GDL were analyzed through discussion. The research trends of the GDL were proposed as well.
This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of ...
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This paper modeled a single cell with active area of nearly 50 cm2 by the CFD software of Fluent and discussed the influence of cooling water on the temperature distribution of membrane. The results show that most of the cooling water's temperature is low, the effect of heat exchange is bad;At the high current density, cooling water with the same flow direction of reactant gas has better effect on improving temperature distribution in the fuel cell. Increasing overall flow velocity and depressing the inlet temperature of cooling water has little effect on improving temperature distribution.
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.
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