高压物理学报

Enhancement of Both Ionic Conductivity and Permittivity of the High Polymer Film P(EO)n-CuBr2 under Hydrostatic Pressure (Ⅱ)－Application of Method to Add Plasticizer

SU Fang, DAI Wei-Ping, SU Xiao

2001, 15(3): 161-168 . doi: 10.11858/gywlxb.2001.03.001

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Abstract:
Through the addition of different weights of non-aqueous CuBr2 to polyethylene oxide (molecular weight 5106), a series of high polymer film P(EO)n-CuBr2 (mole ratio n=[EO]/[Cu]=4, 8, 12, 16, 24) were prepared with the method of mixed solution and evaporation in vacuum. Their relative permittivity was measured in detail under hydrostatic pressure from 0.1 MPa to 2443 MPa. The effect of content of plasticizer (C4H6O3) on both ionic conductivity and permittivity at room temperature and under 1 atmosphere or high pressure were studied respectively. The experimental results show that the film P(EO)n-CuBr2 mingled with plasticizer C4H6O3 which possesses higher permittivity and extremely low intrinsic viscosity when the concentration nPC/ntotal=20%, not only has ionic conductivity at room temperature and under 1 atmosphere enhanced 6.8 times, but also has ionic conductivity under high pressure enhanced from one order of magnitude (under 0.1~100 MPa) to two orders of magnitude (under 250~800 MPa). The enhancement contributes greatly to the application of the film in high pressure state.

Experiments on Reaction of Polyethylene and Water under High Pressure and High Temperature

XIAO Wan-Sheng, WENG Ke-Nan, Lü Guang-Cai, WANG Ben-Shan

2001, 15(3): 169-177 . doi: 10.11858/gywlxb.2001.03.002

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Abstract:
Hydrous and anhydrous pyrolysis of polyethylene under high temperature and high pressure was conducted in diamond anvil cell (DAC) apparatus. Reaction phenomena can be observed by microscope and be recorded by micrography during the experimental processes. At the meantime, in situ fluorescence change can be determined under high pressure. Compositions of gas products were analyzed by gas chromatographic technique. It shows that CH4 make up about 92% of the total gas hydrocarbon products, CO2 and very little solid residue were existed in the hydrous pyrolysis experiment. The results indicate that H2O participates in the chemical reaction directly, offering H to hydrocarbons and O to CO2. Anhydrous pyrolysis of polyethylene generates less gas hydrocarbons and much more solid residue than hydrous run. Thermodynamic theory was used to discuss reaction mechanism in the experiments. Compared polyethylene structure with kerogen, we infer that the ratio of hydrocarbons generation would be increased while H2O exist in the organic matter pyrolysis processes.

Investigations of Complex Fractal Structures with Self-Similarity and Self-Affinity on Fractured Surfaces

TIAN En-Ke, LONG Qi-Wei

2001, 15(3): 178-185 . doi: 10.11858/gywlxb.2001.03.003

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Abstract:
An extensive study of cracked surfaces under complex loading which showed self-similar and self-affine fractal properties was performed. Fractal analysis of the fractured surfaces with fractal dimension D or roughness index H was also discussed. The results indicated that the relations between D and H (D+H=2 or DH=1) were only a rough estimation. Experimental curves that are not straight line in the log-log plot, if you measure the fractal dimension or roughness index of cracked surfaces, could not mean no fractal structure. It might be fractals with mixed structure of self-similarity and self-affinity.

Theoretical Research on the Hugoniot Curves of the Mixtures of Carbon and Water

LIU Fu-Sheng, HONG De-Gui, ZHOU Xue-Fen

2001, 15(3): 186-192 . doi: 10.11858/gywlxb.2001.03.004

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Abstract:
In this article, the Hugoniot curves of graphite-water and diamond-water mixtures, with the initial densities of 1.233 g/cm3 and 1.238 g/cm3 respectively, are calculated by use of the two-phase mixing-model and the fluid perturbation variational statistical theory. The results are: (1) The difference between the Hugoniot curves of these two mixtures is small below 20 GPa where the graphitediamond phase transition and chemical reactions are supposed not to occur. (2) When the shock pressure is beyond 20 GPa where the phase transition is considered to happen without any chemical reactions, these two curves are apparently different from each other, and the graphite-water mixture easier to be compressed. (3) The chemical reactions in these two mixtures at the pressure range of 45~60 GPa will not change the trend of these two Hugoniot curves obviously. These conclusions are contrary to the experimental results published recently (in Chin. J. High. Press. Phys. 13(2), p87). The reliability of the experimental data and the theoretical explanations in that paper are questioned.

Study on Solubility Speciation of Water in Albite Melts

SUN Qiang, ZHENG Hai-Fei, XIE Hong-Sen, GUO Jie

2001, 15(3): 193-198 . doi: 10.11858/gywlxb.2001.03.005

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Abstract:
On the basis of FTIR spectroscopy study on hydrous albite glasses, it is concluded that water dissolves into melts as OH- and H2O simultaneously and these are accordance with 4 500 cm-1 and 5 200 cm-1 in FTIR spectra respectively. In addition, studies also indicate that OH- is dominant in the early solubility and H2O becomes important with higher water contents. And the change of water solubility speciation in melts is agreement with the character of hydrous melt.

Separability of Specific Volume and Its Application to Free-Gas Model of Thermoelectrons

GENG Hua-Yun, TAN Hua, WU Qiang

2001, 15(3): 199-204 . doi: 10.11858/gywlxb.2001.03.006

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Abstract:
Two kinds of systems whose specific volumes can be separated into several parts according to Hamiltonian have been obtained in a grand ensemble. These systems' Hamiltonians are absolutely separable or the chemical potentials of those whose Hamiltonians are not independent can be yielded via respective free energies. On this basis, the partial specific volume contributed by thermoelectrons in metals under a free-gas approximation and the corresponding Wu-Jing parameter are studied as a brief example.

Study on Dynamic Mechanism of Cellular Structure

HU Xiang-Yu, ZHANG De-Liang

2001, 15(3): 205-214 . doi: 10.11858/gywlxb.2001.03.007

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Abstract:
In this paper, the regular detonation cells were divided into the primary units, referred to as sub-cells of cellular detonation. By examining the dynamic process of detonation waves propagating along these sub-cells, theoretical analysis was conducted to study the dynamic mechanism of the two-dimensional idealized detonation waves in gaseous mixtures. Based on the theory of oblique shock waves, a analytical formula was derived to describe the relation between the Mach number ratio through triple-shock collision and the geometric properties of detonation cell. From this formula the incident angle can be also calculated. By applying a modified blast wave theory, and analytical model was developed to predict the dynamic process of detonation waves along the sub-cell. The results calculated from the analytical model show that detonation waves are, first, strengthened at the beginning of the sub-cell after triple-shock collisions, and then decay until the detonation waves reach the sub-cell end. These analytical results were compared with experimental data and previous numerical results, the agreement between them appears to be good, in general.

Theoretical Calculation of Transformation Pressure in Solid Hydrogen Metallization

LI Jun-Jie, ZHU Zai-Wan, JIN Zeng-Sun, ZOU Guang-Tian

2001, 15(3): 215-220 . doi: 10.11858/gywlxb.2001.03.008

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Abstract:
In this paper, the metallic transformation pressure of solid hydrogen is calculated by using the simple metal Pseudopotential method, the possible structures of metallic hydrogen as well as the mechanical and thermal properties of this matter are investigated. The calculation shows that the transformation pressure is pt=465.95 GPa, at which the molecular state solid hydrogen (HCP structure) transforms into atomic phase metallic hydrogen (FCC structure) under absolute zero temperature condition.

A Problem in Measurements of High Pressure Melting Curve of Iron: Influence of Melting Mechanism on the Melting Temperature

LI Xi-Jun, GONG Zi-Zheng, LIU Fu-Sheng, CAI Ling-Cang, JING Fu-Qian

2001, 15(3): 221-225 . doi: 10.11858/gywlxb.2001.03.009

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Abstract:
High pressure melting curve of iron is crucial in modeling the earth's core. But a system deviation exists between the experimental data of static high-pressure experiments and those of the shock wave experiments. With the help of detailed analysis of possible melting mechanism in the two kinds of experiments, we correct the melting data directly from the experimental results and get a self-consistent high pressure melting curve of iron. This melting curve indicates the melting temperature of iron at the core/mantle boundary is about 3 850 K, and 6 000 K at the inner/out core boundary. This result is also consistent with the recommended value by Anderson.

High Pressure Synthesis of Bulk MgB2 Superconductor

LI Shao-Chun, ZHU Jia-Lin, YU Ri-Cheng, LI Feng-Ying, LIU Zhen-Xing, JIN Chang-Qing

2001, 15(3): 226-228 . doi: 10.11858/gywlxb.2001.03.010

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Abstract:
Bulk MgB2 superconductor is synthesized through high pressure sintering. The sample having been obtained shows a good single phase. Magnetic measurements and resistivity measurements at low temperature indicate a sharp superconducting transition above 39 K. The experiment results highlight that high pressure synthesis would be a very effective way to promote the studies of the new kind superconductor of intermetallic compounds.

The Effect of cBN Inclusions on the Densification and Microstructure of Fine-Grained Polycrystalline Diamond Compact

ZHOU Zhen-Jun, LI Gong, YANG Zheng-Fang, CHEN Yu-Ru

2001, 15(3): 229-234 . doi: 10.11858/gywlxb.2001.03.011

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Abstract:
Commercially available synthetic powders of diamond and cubic boron nitride less than 0.5 m were used as the raw materials. Sintering of a fine-grained polycrystalline diamond compact with grains less than 1 m in size was successfully carried out by making a laminate on a WC/Co powder compact under sintering conditions of 6.0 GPa and 1 450 ℃ to 1 480 ℃ for 30 min. The effect of cBN inclusions on the densification and microstructure of the polycrystalline diamond compact was investigated in detail. Results showed that cBN played the role of suppressing abnormal grain growth during sintering. The wear resistance of sintering diamonds with different volume fraction of cBN under sintering conditions of 6.0 GPa and 1 360 ℃ to1 480 ℃ for 30 min was measured. The microstructure of the polycrystalline diamond compact was observed by scanning electron microscope (SEM).

Graphitization Process of Diamond Surfaces During the Sintering of Diamond-Cobalt System under Pressure and Temperature

DENG Fu-Ming

2001, 15(3): 235-240 . doi: 10.11858/gywlxb.2001.03.012

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Abstract:
The conditions of graphitization on diamond surface under high temperature and the graphitization process of diamond under high pressure and temperature were investigated experimentally. The graphitization on the surface of diamond near WC-Co substrate was discovered in samples sintered at the temperature below the cobalt-diamond eutectic point. The XRD testing results show that the diamond powders experienced three graphitization stages during the sintering process under high pressure and high temperature, they are, graphitization accelerated stage, climax stage and restrained stage.

2001 Vol. 15, No. 3

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