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Xu Y.-X.,Beijing Institute of Technology | Wang S.-S.,Beijing Institute of Technology | Zhu X.-Q.,China South Industries Group Corporation
ICCASM 2010 - 2010 International Conference on Computer Application and System Modeling, Proceedings | Year: 2010

In the present study, a lot of numerical analysis and experiments were performed to investigate the penetration power of jet under great standoff distance. In the Numerical simulation, the finite element model was built based on the representative shaped charge. Through computation on nonlinear dynamics AutoDyn program, the penetration characteristics that jet shaped by representative charge impact on the semi-infinite steel target and interval plates under different standoff was obtained; base on these, under the same condition, the static explosive experiments that the jet impact on the interval plates under different standoffs were done, the variety rule between the standoff and layer number penetrated by jet was obtained. The outcomes between experiments and numerical simulation were consistent. It was indicated that the numerical simulation method was correct and available. © 2010 IEEE. Source

Zhao Y.,Beihang University | Li J.-P.,Aerospace Research Institute of Materials And Processing Technology | Wang T.-Y.,Beihang University | Li R.-X.,Beihang University | And 2 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2016

ZrB2 nanoparticles were synthesized synergistically by Sol-Gel method and carbothermal reduction reaction using zirconium n-propoxide, acetic acid, boric acid and xylitol as starting materials. In the reaction system, xylitol acted as a carbon source for the carbothermal reduction reaction and chelated boron, leading to the formation of coordination compound through its polyhydroxy reaction with boric acid. According to the Fourier Transform infrared spectra and thermal analysis of gel precursor, the effects of sol and gel reaction processes on the carbothermal reduction reaction temperature and gelation time were discussed. The results show that the polyhydroxy compound of xylitol is beneficial to initiate reactions and gelation, which makes the threshold throughout the whole chemical processes easy to overcome. The gel does not need aging treatment and the reaction temperature is lowered. Besides, a single phase of equiaxed ZrB2 nanoparticles could be obtained from nascent state gel calcined at 1450℃ with n(xylitol)/n(zirconium n-propoxide) of 1.4. The average diameter and oxygen content of ZrB2 nanoparticles are ca. 50 nm and 1.36wt%, respectively. © 2016, Science Press. All right reserved. Source

Wu S.-S.,South China University of Technology | Hu A.-T.,South China University of Technology | Du J.,China South Industries Group Corporation
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2015

In this paper, first, novel mechanical principle-based extrusion equipment with axial screw vibration is designed, and the principle of the axial screw vibration is analyzed. Then, according to the theory of envelopes, the mathematical equations of the undulant vibration surface are established, and a 3D model of the extrusion equipment is constructed. Moreover, by the force analysis of the vibration parts, a physical model describing the screw vibration is established, and the key parameters are theoretically inferred out. Finally, in ADMAS environment, a dynamic simulation of vibration characteristics of the extrusion equipment is carried out. The results show that the designed extrusion equipment exhibits a simple harmonic vibration waveform with small distortion and high stability, which means that the equipment is feasible and effective. ©, 2015, South China University of Technology. All right reserved. Source

Yang B.-Y.,Beihang University | Li J.-P.,Aerospace Research Institute of Materials And Processing Technology | Wang T.-Y.,Beihang University | Li R.-X.,Beihang University | And 2 more authors.
Wuji Cailiao Xuebao/Journal of Inorganic Materials | Year: 2014

ZrB2 particles were synthesized by a Sol-Gel method using zirconium n-propoxide, boric acid, acetic acid and D-fructose. D-Fructose acts as both a modifier and a carbon source for carbothermal reduction reaction. For comparison, both nascent state gel and aged gel were used to clarify the aging-time-dependent mechanism for ZrB2 synthesis. As a result, a single phase ZrB2 powder with a uniform size and shape distribution can be obtained from the aged gel with a boron and carbon to zirconium molar ratio of 3.5-4 and 7, respectively, after reduced at 1550°C for 2 h. Besides, the synthesized ZrB2 particles exhibit prism-like morphology with average particle size of ca. 4-7 μm in length, 1 μm in diameter of excircle of the cross-section and 4-7 in aspect ratio, when initial raw materials ratio n(B)/n(Zr) is 3.5-4 and n(C)/n(Zr) is 7. The median diameter D50 is 6.46 μm and specific surface area is about 2.53 m2/g. Furthermore, a complete carbothermal reduction of ZrO2 can be achieved using the aged gel. Source

Zhang S.,Beihang University | Xu Y.,Beihang University | Wang T.,Beihang University | Li R.,Beihang University | Cai H.,China South Industries Group Corporation
Jinshu Xuebao/Acta Metallurgica Sinica | Year: 2016

CeO2 is an important rare earth oxide and can be used in automotive exhaust three-way catalysts on the basis of its oxygen storage capability. Ion doping is an effective method to enhance the oxygen storage capability of CeO2. And when doping a cation whose size is smaller than Ce4+ and valence is lower than +4, it tends to evolve more defects. It is known that defects play important roles in enhancing the oxygen storage capability of CeO2. Therefore, In ion was selected as a dopant cation which matches above two factors of size and valence. In this work, a series of CeO2 with different content of In3+ were synthesized via a two-step process. The precursor was synthesized by a solvothermal method at 200℃ using a mixture solvent of (CH2OH)2 and H2O, as well as Ce(NO3)3·6H2O and In(NO3)3·4.5H2O as Ce and In sources, respectively. CeO2 was obtained after the precursor was calcined at 500℃ for 2 h in air. It was found that the solid solubility of In3+ in CeO2 was 1% (molar fraction). The doping of 1%In3+ in CeO2 almost had no impact on the morphology of multilayered structure. However, a second phase of small particles appeared and there were some changes of the morphology of multilayered structure when the concentration of In3+ increased further. The specific surface area of the 1%In3+ solid solution was 100 m2/g, which was th highest among all the samples, and undoped CeO2 (92 m2/g) ranked second. When the content of In3+ was above the solid solubility,i.e., 1%In3+, the specific surface area decreased. The low temperature oxygen storage capability could be improved from 3.6×10-4 mol/g for undoped CeO2 to 4.4×10-4 mol/g for 1%In3+-doped CeO2. When the In3+ content was greater than or equal to 3%, the low temperature oxygen storage capability decreased at the beginning, and then almost no change. Lattice parameter decreased and the concentration of Ce3+ and oxygen vacancy increased by the doping of In3+. Moreover, lattice parameter, the specific surface area, concentration of oxygen vacancy and low temperature oxygen storage capacity could mark a turning point for 1%In3+. It could be found that the low temperature oxygen storage capability was in relation to both the specific surface area and the concentration of oxygen vacancy of CeO2. In addition, the low temperature reduction peaks shifted towards lower temperatures with the addition of In3+. © All right reserved. Source

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