Two types of Mg-Cu composition system graded density impactors used for complex loading （shock loading and quasi-isentropic compression） are designed by the elastic-plastic hydrodynamic method in this paper. Mixture...
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Two types of Mg-Cu composition system graded density impactors used for complex loading （shock loading and quasi-isentropic compression） are designed by the elastic-plastic hydrodynamic method in this paper. Mixtures of metal powders in the Mg-Cu system are cast into a series of 17 and 25 uniform compositions ranging from 100% Mg to 100% Cu. The graded den- sity impactors are launched to the stationary 10 Ixm aluminum film and 12 mm LiF window targets by a two-stage light-gas gun in the National keylab.ratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, CAEP, and the resulting wave profiles are measured with the DISAR system. Hydrodynamic simulation results are perfectly consistent with the experiments. Our work in this paper will set up a foundation for further research of controllab.e loading/releasing routes and rate experiments in the future.
The directional solidified blade castings are wildly used in aero-engines, because the directional solidified microstructure leads to excellent high temperature performance. A very strict process control is needed to ...
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ISBN:
(纸本)9781118029459
The directional solidified blade castings are wildly used in aero-engines, because the directional solidified microstructure leads to excellent high temperature performance. A very strict process control is needed to avoid stray grains. In recent years, liquid metal cooling (LMC) is used as a new process to manufacture blade castings, and still needs to be improved. The numerical simulation of the LMC process is helpful to optimize the technical parameters and reduce the development cycle and cost. In this paper, a model of a LMC process considering the convection between the shell and the cooling liquid metal was established. Different LMC solidification processes were simulated. The results indicate that higher withdrawing rate or lower cooling liquid metal temperature can obtain higher temperature gradient and lead to thinner mushy zone. However, if the withdrawing rate is too high, the mushy zone becomes concave.
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.
A novel Coupled and Self-adaptive (COSA) finger with double-bar parallel mechanism is proposed. As a further attempt to achieve the efficient combination of coupled and self-adaptive motion, the finger conducts humano...
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Silver nanoparticles were prepared by pulsed wire discharge (PWD) using silver wire in deionized water at various relative energy (K) from 10 to 98, which is ratio of the charged energy of the capacitor in the electri...
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Silver nanoparticles were prepared by pulsed wire discharge (PWD) using silver wire in deionized water at various relative energy (K) from 10 to 98, which is ratio of the charged energy of the capacitor in the electrical circuit to the vaporization energy of the wire. From energy deposition calculated by the measured voltage and current waveforms, deposited energy of the wire was increased with increasing K. From X-ray diffraction (XRD) analysis, prepared nanoparticles were phase identified as silver. From transmission electron microscopy observations, the shape of prepared silver nanoparticles were spherical and the median particle diameter (D50) and the geometric standard deviation (σg) were calculated from the particle distribution. D50 was decreased from 34 to 19 nm with increasing K. The particle size in prepared by PWD in liquid media can be controlled by K.
A novel method based on radio frequency magnetron sputtering tailored to the deposition of low residual stress and adherent c-BN thin films on silicon substrates was developed. In this study, the effect of noble gas (...
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A novel method based on radio frequency magnetron sputtering tailored to the deposition of low residual stress and adherent c-BN thin films on silicon substrates was developed. In this study, the effect of noble gas (Kr, Ar, Ne and He) added in Ar gas during sputtering on the residual stress and the c-BN content has been investigated. As a result, it was found that the residual stress of c-BN thin film decreased with increasing the helium gas flow rate within argon gas.
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