高压物理学报

The Structural Stability and Electrical Properties of Nanometer-Scale Sr2FeMoO6 Polycrystals under High Pressure

ZHANG Jiang-Shan, E Bei, YU Ri-Cheng, LI Feng-Ying, LI Xiao-Dong, LI Yan-Chun, MA Mai-Ning, LIU Jing, LIU Zhen-Xing, BAO Zhong-Xing, et al.

2004, 18(3): 193-197 . doi: 10.11858/gywlxb.2004.03.001

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Abstract:
Double perovskite structural compounds Sr2FeMoO6 powders with grain sizes of 50 nm (sample A) and 100 nm (sample B) have been synthesized using polymer-network gel method. Their structural stabilities and electrical properties under high pressure have been investigated. As compared with the result of bulk sample C with m grain size obtained before, the sample A shows the largest bulk modulus B0 among the three and largest pressure region for the drop in the curve of resistance versus pressure. The results can be explained in terms of the effect of large amount grain boundaries in nanometer-scale materials. On the basis of the results of resistance and capacitance versus pressure, it is considered that both samples undergo an electronic structural transition under high pressure.

Studies on Explosion Distortion and First Breakdown under Explosive Detonation

HU Dong, HAN Zhao-Yuan, ZHANG Shou-Qi, ZHAO Yu-Hua, WANG Bing-Ren, CHEN Jun, CAI Qing-Jun, YAO Xie-Cheng, DONG Shi, SUN Zhu-Mei

2004, 18(3): 198-202 . doi: 10.11858/gywlxb.2004.03.002

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Abstract:
The distortion process of the charge envelope and first breakdown is studied in order to understand the formation process of explosion breakdown. The distortion process driven by explosive detonation is observed by means of schlieren technique. A large distortion medium－water is chosen as the sample for observation. The experimental observations show that the expansion of water in cylinder starts from the end of initiation for initiator, then forms a slant and wave interface. The results indicate that the breakdown of the wave interface starts with an outside. It is an important reason that the instability of interface may make it to destabilize and to break. It is observed experimentally that the matter dimension becomes smaller and smaller at different delay time after the explosive detonated. The influences of explosive detonation light on figure and of explosion vibration on light path were overcomed. A simple trigger was developed, and the problem of synchronization of outside light source with explosive initiation was resolved.

2-D Nummerical Simulation of Characteristics of Underwater Explosions

LIANG Long-He, CAO Ju-Zhen, YUAN Xian-Chun

2004, 18(3): 203-208 . doi: 10.11858/gywlxb.2004.03.003

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Abstract:
The characteristics of underwater explosions, especially the distributions and the time histories of shock wave overpressures, which are generated by the underwater explosions of cased cylindrical charges initiated in one-end-point, are numerically simulated by using a two-dimensional multi-fluid hydrodynamic fortran code named MFIC. The cylindrical charges studied here are of four different explosives, including TNT, RS-211, T/ (35/65) and ROT901. For each explosive four TNT equivalents, 1 kg, 3 kg, 5 kg, and 8 kg, are considered. Each cylindrical charge has a length to diameter of L/D=1.5 and with a 3 mm thick Fe case or Al case. The spacial distributions of peak overpressure of underwater shock wave and overpressure time histories are obtained. Some overpressure time histories of different points and of different explosives for both Al case and Fe case are presented. The results of Fe case are compared with those of Al case.

A Discussion on the Mechanism of Shock-Induced Transformation of Graphite to Diamond

ZHANG Wan-Jia

2004, 18(3): 209-219 . doi: 10.11858/gywlxb.2004.03.004

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Abstract:
By comparison of two models of phase transition for graphite to diamond and the analysis of shock wave behaviour in porous materials, the formation mechanism of hot spot and the anonalous atoms transfor mechanism have been discussed. Also, the transition process of graphite to diamond at hot spots region in shock wave front and the regraphitization process upon unloading have been analyzied.

Study of the Products of C3N6H6 Treated at High Temperature and High Pressure

YAO Li-De, YU Ri-Cheng, LI Feng-Ying, LIU Zhen-Xing, LI Ji-Xue, JIN Chang-Qing

2004, 18(3): 220-224 . doi: 10.11858/gywlxb.2004.03.005

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Abstract:
A black-brown powder was synthesized from melamine (C3N6H6) by means of high temperature and high pressure. Based on the analysis of X-ray diffraction patterns, the powder is composed of some un-decomposed raw material, carbon and intermediate phases. The existence of the intermediate phase with long periodicity along one direction is confirmed from transmission electron microscopy observation; Scanning electron microscopy shows many block tissues, in which a few holes exist; The atomic ratio of carbon and nitrogen is determined as 3.27∶1 in the powder from the measurement of Energy Dispersive X-ray Analysis. The high content of C is caused by the existence of carbon decomposed from the raw materials. In addition, the chemical bond states are investigated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. As a result, the main bond styles in the powder are described as C(sp2)=N and C(sp2)N.

Application of Fiber Velocity Interferometer System for Any Reflector in High Pressure Physics

WENG Ji-Dong, TAN Hua, CHEN Jin-Bao, JIA Bo, HU Shao-Lou, MA Yun, WANG Xiang

2004, 18(3): 225-230 . doi: 10.11858/gywlxb.2004.03.006

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Abstract:
On the basis of traditional velocity interferometer, a fiber velocity interferometer system for any reflector (FVISAR) with wide spectrum laser is illustrated. The important properties of the FVISAR are ideal space interference and convenient delay-time setup. Preliminary tests of FVISAR using Hopkinson Bar system shows that the FVISAR works well for low velocity measurement.

The Experimental and Theoretical Study on the Incident Pulse Shaping Technique

ZHAO Xi-Jin, LU Fang-Yun, WANG Wu, LI Ying-Hua, LIN Yu-Liang

2004, 18(3): 231-236 . doi: 10.11858/gywlxb.2004.03.007

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Abstract:
We modified the conventional Split Hopkinson Pressure Bar (SHPB) technique by shaping the incident pulse such that the samples are in dynamic stress equilibrium and in homogeneous deformation during the tests of silicon rubber. According to the method of pulse shaper designing, we had the samples loaded under constant strain rate, and we got the direct relation between the size of pulse shaper and strain rate. A model to predict the incident waveform in the SHPB experiment by use of a single pulse shaper is built according to the theory of stress wave. Incident waveform from experiment and model prediction with H62 brass shaper are obtained. Model predictions are in good agreement with experimental results.

Adiabatic Compression of Pores in Mixed Fuel Medium During Launching

ZHANG Qi, JI Yan-Hua, BAI Chun-Hua, YAN Hua, ZHAO Yong-Tao, LUO Ai-Min, FU Zhi-Min

2004, 18(3): 237-244 . doi: 10.11858/gywlxb.2004.03.008

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Abstract:
The charge of fuel air explosive (FAE) warhead is usually a solid-liquid mixed fuel, which contains pores to meet the usage and reservation. This study has investigated the influence of pore size on the launching safety by analyzing the physical process of the pore compressing. A criterion is proposed to distinguish the influence of pore size on charge safety in launching, and a quantitative relationship of the launching acceleration, the size of the pore and the temperature of pore in adiabatic compression has been established.

Computer-Aided Design of Explosive Welding Parameter

WANG Tie-Fu

2004, 18(3): 245-251 . doi: 10.11858/gywlxb.2004.03.009

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Abstract:
A computer-aided design program for explosive welding parameter was developed. Using Visual C++, it is convenient to import and export data by menu as well as visual operations. In comparison with the result of explosive welding test, it was shown that the optimum value of the parameter calculated with the CAD program was in agreement with the experimental result exactly. Using the CAD proposed here, it will be useful to both select the optimum parameter for explosive welding and reduce trial-and-error.

Theoretical Study on High Pressure Liquid Sintering of Polycrystalline Diamond Compact

DENG Fu-Ming, ZHAO Guo-Gang, WANG Zhen-Ting, GUO Gang, LIU Xiao-Hui, CHEN Qi-Wu

2004, 18(3): 252-260 . doi: 10.11858/gywlxb.2004.03.010

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Abstract:
Based on the theoretical analysis of the interaction between diamond and melted cobalt under HP/HT conditions, the effect of temperature and carbon content of the melted cobalt on the sintering process of diamond dissolution and polycrystalline diamond growth are discussed. It is suggested that the diamond is preferable to graphite to dissolve in the melted cobalt under HP/HT and there are three sintering mechanisms in the diamond-cobalt sintering system, that is, the mechanism of diamond rearrangement, dissolution and precipitation and formation of the direct bonding of diamond to diamond. The melted cobalt with different carbon content and temperature can play an important role to weak or cease the covalent bond of diamond at its surfaces, to promote the rearrangement of diamond, to realize the transportation of diamond atoms and finally to form the diamond to diamond bonding structure of polycrystalline diamond. According to the high pressure liquid sintering theory of diamond proposed in this paper, some experimental phenomena found during the HP/HT sintering process of polycrystalline diamond compacts could be explained rationally.

Response of Homemade PVDF Piezofilm under Shock Loading and Unloading

LI Yan, ZHANG Xiang-Rong, TAN Hong-Mei, LIU Xiao-Ling, PEI Ming-Jing

2004, 18(3): 261-266 . doi: 10.11858/gywlxb.2004.03.011

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Abstract:
For two kinds of homemade PVDF piezofilm, the shock loading stress-charge curves were calibrated, using light gas gun and shock tube respectively. Results were compared with some other homemade and overseas' PVDF. By measuring the particle velocity in the step-release experiment, the shock release behavior of PVDF was also studied. The hystersis of PVDF was found obviously.

Effects of Electronic Structures on Volume Compressed Borides

CHAI Yong-Quan, JIN Chang-Qing, LIU Bang-Gui

2004, 18(3): 267-272 . doi: 10.11858/gywlxb.2004.03.012

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Abstract:
An accurate first-principle density-functional method was used to calculate the twenty borides after their volume were compressed. The electronic structures were compared to each other and their dependence on cell volumes was made clearly. These results may be helpful to modulate physical properties of the borides under pressure.

Optimization of Conditions to Sterilize Staphyloccus Aureus by Ultra-High Hydrostatic Pressure Using Response Surface Methodology

GAO Yu-Long, WANG Yun-Xiang, JIANG Han-Hu

2004, 18(3): 273-278 . doi: 10.11858/gywlxb.2004.03.013

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Abstract:
The results of factorial experiment showed that the significant external factors affecting UHHP sterilization were pressure, temperature and pressure holding time. Based on the results, response surface methodology (RSM) was employed and a second order quadratic equation for UHHP sterilization was built in the present work. The applicability of the model equation for predicting the optimum response values was verified effectively by the validation data. By analyzing the response surface plots and their corresponding contour plots as well as solving the quadratic equation, the optimum process parameters for sterilization Staphyloccus aureus of six log cycles were obtained as: temperature 34.35 ℃, pressure 329.84 MPa, and pressure holding time15.53 min.

Dynamic Piezoresistance Response of Array MnCu Film Gauges

TENG Lin, YANG Bang-Chao, DU Xiao-Song, ZHOU Hong-Ren, CUI Hong-Ling

2004, 18(3): 279-282 . doi: 10.11858/gywlxb.2004.03.014

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Abstract:
Array MnCu film piezoresistance gauges were fabricated by D.C. magnetism sputtering with 99% Al2O3 taken as substrate and insulator. Four MnCu gauges with the same resistance were deposited on one Al2O3 substrate symmetrically. Through dynamic loading experiments at the pressure of 51.72 GPa, it is indicated that four piezoresistance gauges have good consistency, and keep insulating trait under high pressure, which verifies the reliability of dynamic testing of MnCu film piezoresistance gauges.

UHP Waterjet Remove Rust Technology and Its Stage Equations

XUE Sheng-Xiong, WANG Le-Qin, PENG Hao-Jun, FAN Yi-Bin, CHEN Zheng-Wen, WANG Yong-Qiang, YU Lei, ZHU Hua-Qing

2004, 18(3): 283-288 . doi: 10.11858/gywlxb.2004.03.015

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Abstract:
Rusting with water, but removing with water too. Ultra-high pressure waterjet with pressure 200~250 MPa has been used to remove rust automatically and to prevent from re-rusted in a series of testing research. This paper describes the creation of a new assemblied ultra-high pressure waterjet rust removal set-up and its working principle in every step, including jet formation, flow-yard model and working efficiency.

2004 Vol. 18, No. 3

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