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.
Sodium niobate (NaNbO3) nanometer-size particles having antiferroelectric property were successfully prepared via a hydrothermal process. When NaOH, about 8~10 times as much as Nb2O5(3~4 mol/L NaOH), reacted with Nb2O...
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Sodium niobate (NaNbO3) nanometer-size particles having antiferroelectric property were successfully prepared via a hydrothermal process. When NaOH, about 8~10 times as much as Nb2O5(3~4 mol/L NaOH), reacted with Nb2O5 particles at 160~180°C under hydrothermal conditions, pure orthorhombic phase NaNbO3 characterized by using X-ray powder diffraction was obtained. The unit cell parameters were a = 9.5597, α = β = γ = 90°, c = 5.7873. The hydrothermal reaction significantly lowered the temperature required for synthesizing NaNbO3 and the size of NaNbO3 particles. And TEM analysis showed the size of NaNbO3 particles was about 0.02~0.05 μm.
Ca3Cc2O6 is one kind of potential oxide thermoelectric materials. Sol-gel method was applied to synthesize Ca3Co2O6 powder, dried gel and powders are studied systemically with testing measures of the TG/DSC, XRD and S...
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Ca3Cc2O6 is one kind of potential oxide thermoelectric materials. Sol-gel method was applied to synthesize Ca3Co2O6 powder, dried gel and powders are studied systemically with testing measures of the TG/DSC, XRD and SEM. The pH, glycol and calcined temperature were taken into account as main influence factors. It was found during the research that the use of glycol can lighten agglomerates, benefit to auto-combustion, and had no effect on the phases finally. At the same time, Ca3Co2O6 was the offspring of decomposed Ca3Co4O9 at certain calcined condition.
The effects of fuel cell structures and operating condition on the performance of proton exchange membrane fuel cells are discussed. The results show: there are optimal ranges about the contents of PTFE and Nafion in ...
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The effects of fuel cell structures and operating condition on the performance of proton exchange membrane fuel cells are discussed. The results show: there are optimal ranges about the contents of PTFE and Nafion in catalyst layers. Fine fuel cell structures and scales are benefit to the uniform distribution of reaction gas, the discharging of production, the reduction of fuel cell internal resistances. Increasing the porosity and aperture of diffusion layers can increase the limiting current density of fuel cells. Decreasing the thickness of the membrane will decrease the internal resistances of fuel cell. Raising temperature and pressure will improve electrochemical reaction and reduce transport resistances. The humidification temperature and velocity of the reaction gas should vary with the current density.
The relations among composition, structure, chemical bond and property of composites of TiC/Al2O3 ceramic and doped series are studied by using density function and discrete variation method (DFT-DVM). There are stron...
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The relations among composition, structure, chemical bond and property of composites of TiC/Al2O3 ceramic and doped series are studied by using density function and discrete variation method (DFT-DVM). There are strong ionic and covalent interactions between two phases of TiC/Al2O3, the interaction becomes stronger when doping Ni into TiC/Al2O3, and the interaction of doping Mo into TiC/Al2O3 is stronger than that of doping Ni. The results are consistent with the experiment that doping can improve the combination of the phases in TiC/Al2O3, enhance hardness and et al, and the improvement of doping Mo is more obvious than that of doping Ni.
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