A 3-D finite element model of two-stage thermoelectric generator based on low-temperature thermoelectric material bismuth-telluride and medium-temperature thermoelectric material skutterudites is established. Based on...
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B4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity...
B4C ceramics doped with various content of Si (0 to 2.03 at%) are prepared via hot pressing. The composition and microstructure of the ceramics are characterized by means of XRD and EPMA. Their electrical conductivity and Seebeck coefficient of the samples are measured from room temperature up to 1500K. The electrical conductivity increases with temperature, and more rapidly after 1300K; the Seebeck coefficient of the ceramics also increases with temperature and rises to a value of about 320μVK−1. The value of the figure of merit of Si-doped B4C rises to about 4 × 10−4 K−1 at 1500K.
The process of performance degradation of road asphalt(RA)is regarded as *** present,better understanding of the thermal-oxidative aging of asphalt is achieved and the corresponding method to evaluate this process is ...
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The process of performance degradation of road asphalt(RA)is regarded as *** present,better understanding of the thermal-oxidative aging of asphalt is achieved and the corresponding method to evaluate this process is developed;meanwhile,photo-oxidative aging(aging in an atmospheric environment,which is referred to as“outdoor aging”in this paper)of asphalt remains at the initial stages of scientific *** outdoor natural ultraviolet(UV)aging of RA and SBS modified asphalt(SBSMA)are investigated in this *** experimental results show that the basic performances of RA and SBSMA present similar change *** softening point increased,while the penetration and ductility decreased as the outdoor aging time passed by,and the 5℃ ductility(ductility measured at 5℃)of SBSMA decreased very *** group components of RA and SBSMA also change during UV *** content of asphaltene rose and that of aromatics and saturates decreased,while the content of resins changed ***,the Fourier transform infrared(FTIR)graphs show that the content of sulfoxide and carbonyl groups in RA and SBSMA increased significantly during the outdoor aging process.
Optical transparency was achieved at infrared region and overall translucent silicon nitride was fabricated using hot press sintering (HPS). The increase in h-BN content decreased the optical transparency. Microstruct...
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Optical transparency was achieved at infrared region and overall translucent silicon nitride was fabricated using hot press sintering (HPS). The increase in h-BN content decreased the optical transparency. Microstructral observations shows that the optical, mechanical and tribological properties of BN dispersed polycrystalline Si3N4 ceramics were affected by the density, α:β-phase ratio and content of h-BN in sintered ceramics. The hot pressed samples were prepared from the mixture of α-Si3N4, AlN, MgO and h-BN at 1850°C. The composite contained from 0.25 to 2 mass % BN powder with sintering aids (9% AlN + 3% MgO). Maximum transmittance of 57% was achieved for 0.25 mass % BN doped Si3N4 ceramics. Fracture toughness was increased and wear volume and friction coefficient were decreased with increase in BN content.
Highly oriented titanate nanotube (TNT) film was successfully synthesized by a simple electrophoretic deposition (EPD) method without any hard templates and surfactants. This oriented films adequately utilized the exc...
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The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is inves...
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The operation characteristics of proton exchange membrane fuel cells with the channel width of 1mm and 2 mm under a medium-pressure are addressed, and the effect of temperature on the operation characteristic is investigated in detail. The results show that fuel cell with a 2 mm channel width can realize the long time operation in a closed-ended situation. The voltage of the 1mm width cell can drop from 0.7 V to 0.5 V in 3 min, while the 2 mm width cell can last for more than 53 min. Moreover, the temperature has a significant effect on the performance, the voltage of the 1 mm width cell can drop from 0.69 V to 0.5 V in less than 1.7 min. The resistance of the cell is increasing with the temperature, but the amplitude is smaller in high temperature.
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