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.
The α-Fe fibers were prepared successfully by the method of electrodepositing in porous alumina template. The results indicated that the diameter of the fibers was 300 nm and the length of them increased along with t...
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The α-Fe fibers were prepared successfully by the method of electrodepositing in porous alumina template. The results indicated that the diameter of the fibers was 300 nm and the length of them increased along with the electrodepositing time increasing. The saturation magnetization per m2 of the iron fibers increased with the increasing of the length/diameter ratio, but the coercive field decreased.
The transport dynamics of proton exchange membrane fuel cell( PEMFC) is very important to understand its working mechanism and to realize optimization control. A single-channel, three-dimensional model has been develo...
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The transport dynamics of proton exchange membrane fuel cell( PEMFC) is very important to understand its working mechanism and to realize optimization control. A single-channel, three-dimensional model has been developed to study the change of relative humidity of reactant and current density;Dynamic simulation includes average number of H2O/SO42- of membrane surface at cathode, diffusion of oxygen, pressure of channel inlet/outlet, gas flow rate and so on. The conclusion has reference significance regarding the correlated research.
In this paper, the weak ferromagnetic properties of polycrystalline Ca1+xB+6 ceramics sintered at different temperature in Ar atmosphere were reported. The results indicated that the CaB2O4 phase appeared at low tempe...
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In this paper, the weak ferromagnetic properties of polycrystalline Ca1+xB+6 ceramics sintered at different temperature in Ar atmosphere were reported. The results indicated that the CaB2O4 phase appeared at low temperature, and the content of the phase decreased with the increasing of the temperature. All the compositions showed ferromagnetic nature at room temperature when x (0.04 which was different from that of single crystal Ca1+xB6.
Microstructures of highly compact IrO2 films, deposited on Si (100) substrates by pulsed laser deposition of Ir target at different oxygen partial pressures, were characterized with X-ray diffraction (XRD), Raman spec...
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Microstructures of highly compact IrO2 films, deposited on Si (100) substrates by pulsed laser deposition of Ir target at different oxygen partial pressures, were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and atomic force microscopy (AFM).The results show that the films, grown at an oxygen partial pressure of 20 Pa and at a substrate temperature in the range of 250°-500°C, are polycrystalline and that as the substrate temperature rises, IrO2 surface becomes rougher with bigger grains.
The nanostructure of the ball milled FeNi particles were characterized as functions of the ball milling time (t) using quantitative X-ray diffraction (XRD), high resolution transmission electronic microscopy (HRTEM) a...
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The nanostructure of the ball milled FeNi particles were characterized as functions of the ball milling time (t) using quantitative X-ray diffraction (XRD), high resolution transmission electronic microscopy (HRTEM) analysis techniques. The results showed that the nanocrystalline bcc FeNi particles were available using carbonyl iron and nickel powders as the raw materials during the high-energy ball milling. After 10 h ball milling, the alloy of carbonyl iron and carbonyl nickel began to form, and the sample kept its original bcc and fcc structure;after 100 h ball milling, the sample became a solid solution with bcc structure;after 200 h ball milling, the diffraction peak of Ni almost disappeared and the isotropic grains with Dmin achieved, which was mainly attributed to the dislocations of the nanocrystalline bcc FeNi suffering from severe plastic deformation by ball milling.
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