A novel method was used to fabricate AIN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate...
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A novel method was used to fabricate AIN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate; secondly, AIN coating was formed through the in-situ reaction of Al with the sprayed BN. The reaction was investigated by thermogravimetric-differential thermal analysis (TG-DTA), and the phase composition in the synthetic process was characterized by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) was used to observe the morphology, and electron probe microanalysis (EPMA) was used to observe the distribution of the elements. The experimental results show that the AIN coating is dense and bonded with graphite tightly.
Based on the electrochemical model, a simulation model has been developed with Matlab/Simulink. Steady-state analysis has been developed to evaluate how the temperature affect the voltage and output power of the fuel ...
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Based on the electrochemical model, a simulation model has been developed with Matlab/Simulink. Steady-state analysis has been developed to evaluate how the temperature affect the voltage and output power of the fuel cell. Dynamic analysis focus on the dynamic response of the output voltage, the output power, the consumed power, the efficiency and the internal resistance of a single PEMFC when the current of a PEMFC increase or decrease transiently. This simulation model also adapted to the simulation of PEMFC stack. The study is helpful for the optimization and control of PEMFC.
Highly conductive IrO2 thin films were prepared on Si (100) substrates by pulsed laser deposition technique from an iridium metal target in an oxygen ambient atmosphere. The effect of substrate temperature on the stru...
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Highly conductive IrO2 thin films were prepared on Si (100) substrates by pulsed laser deposition technique from an iridium metal target in an oxygen ambient atmosphere. The effect of substrate temperature on the structure and electrical properties of IrO2 films was investigated. The deposited films at substrate temperatures ranging from 250 to 500°C under an oxygen pressure of 20Pa were pure polycrystalline tetragonal IrO 2 and the preferential growth orientation changed with the substrate temperature. IrO2 films were well solidified with the fairly homogeneous thickness and exhibited a good adhesion with the substrate. The room-temperature resistivity of IrO2 films decreased with the increase of substrate temperature and the minimum resistivity of (42±6) μΩ·cm was deposited at 500°C.
Potassium lithium niobate (KLN: K3Li2Nb5O15) films have been deposited on quartz glass by Pulsed laser deposition (PLD) technique using a stoichiometric KLN target as starting materials. By investigating the effects o...
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Potassium lithium niobate (KLN: K3Li2Nb5O15) films have been deposited on quartz glass by Pulsed laser deposition (PLD) technique using a stoichiometric KLN target as starting materials. By investigating the effects of both the oxygen pressure and the substrate temperature on the structure of KLN films, optimum parameters have been identified for the growth of high-quality KLN films. At 10Pa oxygen ambient pressure, tetragonal tungsten-bronze-type structure of KLN films with (310) preferred orientation can be achieved at substrate temperatures in the range of 700-800°C Optical studies indicate that the films are highly transparent in the visible-near-infrared wavelength range.
MoSi2 is one of the few intermetallics to have potential for farther systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at h...
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MoSi2 is one of the few intermetallics to have potential for farther systems. However, the use of MoSi2 has been hindered due to the brittle nature of the material at low temperatures, inadequate creep resistance at high temperatures, accelerated (pest) oxidation at temperatures between 450-550°C. In this investigation Mo(Al,Si2)/Ti 3SiC2 composites has been prepared by reaction hot-pressing from Mo, Si, SiC, Ti, Al powder mixture under different temperatures. XRD results show that the main products are Mo(Si,Al)2 and Ti3SiC2. Part of TiC and SiC also appeared at low treating temperature. With the treating temperature increasing SiC disappeared. No evidence show lattice change of Mo(Si,Al)2. It must be the results of sufficient Al added. The electrical conductivity properties were also investigated. Samples treating under different temperatures showed different changes. Samples under high treating temperature showed a near linear change ranging from 27∼800°C and Samples under low treating temperature showed a nonlinear change.
A novel method was used to fabricate AlN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrat...
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A novel method was used to fabricate AlN coating on graphite substrate. This approach included two steps: firstly, the emulsion composed of BN and anhydrous ethanol was sprayed on the surface of the graphite substrate; secondly, AlN coating was formed through the in-situ reaction of Al with the sprayed BN. The reaction was investigated by thermogravimetric-differential thermal analysis (TG-DTA), and the phase composition in the synthetic process was characterized by X-ray diffraction (XRD). Scanning electronic microscopy (SEM) was used to observe the morphology, and electron probe microanalysis (EPMA) was used to observe the distribution of the elements. The experimental results show that the AlN coating is dense and bonded with graphite tightly.
In the present study, Si2N4 whisker was prepared by thermal decomposition of Si(NH)2, the experimental principles and process were described in detail. Influence factors such as temperature, residual carbon(C), a smal...
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In the present study, Si2N4 whisker was prepared by thermal decomposition of Si(NH)2, the experimental principles and process were described in detail. Influence factors such as temperature, residual carbon(C), a small quantity of oxygen and crucible material that could influence the growth of whisker was analyzed and discussed. The influence degree of each factor and mechanism were explained as well. High quality and modified Si3N4 whisker could be prepared by controlling the influence factors during the experimental process. As a result, it was significant to fabricate batch production of high performance Si3N4 whisker by utilizing this method.
Thermogravimetry (TG-DTA) was used to study the heat resistance characteristics and curing heat decomposition kinetics of ATPU/epoxy resin system. Results showed that the decomposition temperature of the cured ATPU-2/...
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Thermogravimetry (TG-DTA) was used to study the heat resistance characteristics and curing heat decomposition kinetics of ATPU/epoxy resin system. Results showed that the decomposition temperature of the cured ATPU-2/E-44 was higher than that of ATPU-1.5/E-44. The calculation results of decomposition reaction showed that the cured system of ATPU-2/E-44 had better heat resistance, the reaction decomposition active energy of ATPU-2/E-44 system was higher than that of ATPU-1.5/E-44.
Ti2AlC bulk material was synthesized by hot pressing using elemental powder mixture of Ti, Al and active carbon. X-ray diffraction (XRD) in different temperature of hot pressing was used to determine the phase composi...
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Ti2AlC bulk material was synthesized by hot pressing using elemental powder mixture of Ti, Al and active carbon. X-ray diffraction (XRD) in different temperature of hot pressing was used to determine the phase composition and scanning electron microscope (SEM) was observed to investigate the microstructure of samples synthesized respectively. Results show that high purity Ti2AlC bulk material was synthesized by hot pressing elemental powder mixture of 2.0 Ti/1.0 Al/1.0 C at 1500 °C for 60 minutes, in which little TiC and Ti3AlC2 existed as secondary phases. According to the results of thermodynamics calculation, for Ti, Al and C system the most stable compound in thermodynamics was TiC. Moreover, the formation of Ti3AlC2 during the synthesizing progress of Ti2AlC was explained.
A kind of p-type segmented Bi2 Te3/CoSB3 thermoetectric material was preparea oy sparse ptasma sintering( SPS ) . When the segmented materials were used at the temperature ranging from 300 K to 800 K, the junction t...
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A kind of p-type segmented Bi2 Te3/CoSB3 thermoetectric material was preparea oy sparse ptasma sintering( SPS ) . When the segmented materials were used at the temperature ranging from 300 K to 800 K, the junction temperature was optimized, which is about 500 K, and the corresponding length ratio of CoSb3 to Bi2 Te3 is about 15 : 2. The measured maximum power output of segmented materials is abont 320 W·m^-2, which is about 1.8 times as high as that of monolithic material CoSb3 under the same measuring conditions.
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