AlN was synthesized by in situ reaction with Al and BN in this paper. AlN-BN composites were fabricated by hot-pressed sintering without additives. The relationship between the ratio of Al to BN and microstructure and...
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AlN was synthesized by in situ reaction with Al and BN in this paper. AlN-BN composites were fabricated by hot-pressed sintering without additives. The relationship between the ratio of Al to BN and microstructure and properties were studied. The results show that the content of AlN increases with the ratio of Al to BN increasing, and the density, hardness, bending strength, thermal conductivity and dielectric constant also increase with the ratio of Al to BN increasing. The results show that the samples with thermal conductivity 63.5 W/m·K and dielectric constant 8.76 are acquired by hot-pressed sintering under nitrogen atmosphere and two hours soaking time.
The hydrophilic-hydrophobic adjustable catalyst layers, with contact angle of 78°-130°, were prepared successfully by using of microemulsion method. The as-result samples were characterized by the I-V curve ...
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The hydrophilic-hydrophobic adjustable catalyst layers, with contact angle of 78°-130°, were prepared successfully by using of microemulsion method. The as-result samples were characterized by the I-V curve of its single cell, EIS, CV, SEM, TEM. It is found that an appropriate dosage of PTFE in the catalyst layers can optimize the micro-structure of the catalyst layer, and improve the stability of the cell. the best composition of the catalyst layer was Pt/C : Nafion : PTFE = 9 : 3 : 1.
Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature...
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Al2O3/WC-10Co/ZrO2 cermets were prepared by a hot-pressing process by using WC-10Co nanocomposite powder, Y2O3 stabilized nanocrystalline ZrO2 powder and submicron Al2O3 powder. The influences of sintering temperature on the microstructure, grain size and properties were investigated according to the density, fracture toughness, Rockwell A hardness (HRA), hysteresis loops and scanning electron microscopy (SEM) micrographs of fractured surfaces of the specimens. The results show that the composite powders (WC-10Co(50%)/Al2O3(40%)/ZrO2(10%)) after being high-energy ball-milled for 48 h was hot-pressing sintered at 1450°C, then submicron Al2O3/WC-10Co/ZrO2 cermets with an average grain size of less than 1 μm and better properties of 97.5% in relative density, 7.4468 MPa·m1/2 in fracture toughness, HRA 94.0 is achieved.
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.
The paper make a brief introduction to PEMFC dynamic model, which shows the development of PEMFC from simple cell to cell system in recent decade. Put forward some problem existing in current dynamic modeling, point o...
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The paper make a brief introduction to PEMFC dynamic model, which shows the development of PEMFC from simple cell to cell system in recent decade. Put forward some problem existing in current dynamic modeling, point out some potential developing direction of modeling: 1) describing cell's inner process from microcosmic side more really, establishing a mechanism model including electrode process dynamic and electrochemistry thermodynamics (energetics);2) from macroscopical side , developing a united mathematic model which can be used to describe PEMFC system roundly from macroscopical side.
The performance of proton exchange membrane is mainly influenced by water content and distribution in proton exchange membrane for PEM fuel cell, and influence factors of the water content and the distribution in memb...
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The performance of proton exchange membrane is mainly influenced by water content and distribution in proton exchange membrane for PEM fuel cell, and influence factors of the water content and the distribution in membrane mainly include the pressure, the temperature, the electric current and so on. This text has discussed the influence of pressure to water content and distribution in proton exchange membrane, and we made the ingenious experimental design to measure directly the distribution of water content in membrane. We have got the disciplines of water content and distribution in membrane under pressure. Experiment reveals that the influence of pressure to water content in membrane is small and water distribution among membrane is average, these conclusions do not accord with model completely.
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.
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