高压物理学报

Experimental Investigation on the Garnet Growth during the Metamorphism of Eclogite Facies

ZHOU Wen-Ge, XIE Hong-Sen, ZHAO Zhi-Dan, GUO Jie, XU Ji-An, BAI Wu-Ming

1999, 13(4): 241-246 . doi: 10.11858/gywlxb.1999.04.001

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Abstract:
The grain growth kinetics of the garnet during the transformation of trachybasalt and andesite to eclogite has been investigated at 2.0～3.0 GPa. The experimental samples were annealed at temperatures of 860 ℃, 870 ℃and 980 ℃ for 0.57 to 13 h. The grain size was determined optically. The normal grain growth of the garnet during the metamorphism of eclogite facies was observed. The grain growth of the garnet increases with increasing annealing time. The rate of the garnet growth decreases with increasing the grain size. However, the rate of the garnet growth during the trachybasalt-eclogite transformation is more rapid than that of the garnet growth during the andesite-eclogite transformation. This phenomenon is attributed to the differences of the chemical compositions and the volatile contents between the trachybasalt and the andesite. In the early stage of the metamorphism of the eclogite facies, the interface-controlled mechanism dominates in the garnet growth.

Equation of State of Detonation Product (Ⅱ)－Does ZND Theory of Detonation Fail? (A)

LI Yin-Cheng

1999, 13(4): 247-254 . doi: 10.11858/gywlxb.1999.04.002

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Abstract:
As a theory, the ZND theory of detonation must be precisely proved true. American scientists had performed the test. They did not give positive conclusion due to lack of the knowledge of the equation of state of the product. A liquid equation of state that describes the interaction between the molecules as strong repellent and all the outer motions of the molecule as free translation is use to do the test by this paper, the ZND theory of detonation is proved true. The liquid equation of state is named repellent-translation EOS, or R-T EOS for short.

Study of Equation-of-State of Dense Helum by Molecular Dynamics Simulation

CAI Ling-Cang, CHEN Qi-Feng, JING Fu-Qian, CHEN Dong-Quan

1999, 13(4): 255-261 . doi: 10.11858/gywlxb.1999.04.003

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Abstract:
The optimized value of =12.7, which is the stiffness parameter in exponential 6 potential function used for describing the compression behavior of dense helium, is determined by means of molecular dynamics simulation and makes comparison with the experimental isotherm of solid helium. Then, we adopt this new value of to calculate the equation of state and the radial distribution function for fcc solid helium at high temperatures, and find while =1.60 g/cm3 the second peak of the radial distribution function would disappear in the regime of 2 000 K to 3 040 K. It demonstrates the long-rang degree of order is degraded or the solid-liquid transition occurs under that condition.

Surface Modification of HDPE and PC under Shock Pressure

LI Peng, LI Liang-Bin, HUANG Rui, CAI Bi-Hua, FAN Wu-Yi, LIU Fu-Sheng, ZHANG Qing-Fu, SHI Shang-Chun

1999, 13(4): 262-267 . doi: 10.11858/gywlxb.1999.04.004

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Abstract:
The surface of HDPE and PC samples undergone transient shock pressure were investigated with ESCA and FT-IR, which show high oxygen/carbon ratio of 0.195∶1 and 0.266 ∶1 respectively, suggest that oxygen-containing groups are rich on the surface. The high pressure and temperature induced by shock are responsible for the chemical reaction directly. Large quantity of reactive sites and macromolecular radicals are formed while carbonization and oxydehydrogenation occurring. They then react with ambient oxygen on the spot, resulting in graft or substitution of the surface material.

Experimental Study of the Effect of Initial Density on Width of Detonation Reaction Zone of JO-9159

ZHANG Zhen-Yu, WANG Zhi-Bing, LU Fang-Yun

1999, 13(4): 268-271 . doi: 10.11858/gywlxb.1999.04.005

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Abstract:
The width of detonation reaction zone of JO-9159 with two different initial densities is measured by embedded electric-magnetic velocity (EMV) gauges. The experimental results show that, for heterogeneous explosives with narrow detonation reaction zone such as JO-9159, the rate of reaction is related to their initial physical properties, even though the detonation wave has reached a steady state.

An One-Dimensional Phase Transition Constitutive Model

WANG Wen-Qiang, TANG Zhi-Ping

1999, 13(4): 272-277 . doi: 10.11858/gywlxb.1999.04.006

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Abstract:
Defects are always existing in real materials, which cause stress concentration. When phase transition takes place, new phase nuclei form first at the positions of defects and then grow via phase boundary propagation. There is a certain relationship between the propagation velocity of phase boundary and the driving force, i.e. the Gibbs free energy difference between two phases. From this point, we have studied the phase transition process of real material with a model of rod containing defects, and have derive a rate-dependent phase transition constitutive relation which in form is similar to generalized Maxwell model. Based on this model, stress profiles of CdS transformation under shock loading were calculated. Results show that our constitutive model can describe the main characteristics of the experimental phenomenon, except the large stress relaxation after the precursor. The calculated were profiles are quite close to those of Fe and InSb, which suggests this model can be applicable to materials other than CdS.

The Influence of the Pressure, Temperature and Time on the Properties of Sintered Diamond Compacts

SUN Zhen-Wu

1999, 13(4): 278-282 . doi: 10.11858/gywlxb.1999.04.007

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Abstract:
The effects of the pressure, temperature and time on the properties of sintered diamond compacts are investigated in infiltrating way in this work; sintered diamond compacts of metal additive with the wear resistance ratio of 285103 and without abnormal diamond grain growth are obtained at 1 400 ℃, 5.8 GPa for 12 min. The effects of sintering ways on sintered result are discussed.

A Method of Locating the Light Spot of Incidence Synchrotron Radiation in EDXRD Experiment under high Pressure

ZHAO Jing, LIU Jing, YANG Yang, GAO Zhen-Hua, CHE Rong-Zheng

1999, 13(4): 283-289 . doi: 10.11858/gywlxb.1999.04.008

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Abstract:
It is a key part to locate the light spot of incidence from 3WB1 beam of line at the sample chamber in a gasket for EDXRD experiments under high pressure using synchrotron radiation. The high pressure station has introduced the system of four-blade-slits which can scan at x-y directions and realize automation of locating the light spot of incidence. Adjusting diffraction path becomes easier than before. Experimental efficiency increases. It is more convenient for external users to carry out EDXRD experiments.

Equation of State for Gas N2 at Low Temperature and High Density

YANG Chuan-Lu, WANG Rong, WANG Fan-Hou, ZHU Zheng-He, WANG Ming-Da, ZHENG Yong-Ming, TANG Yong-Jian, ZHENG Zhi-Jian, ZHAO Yong-Kuan

1999, 13(4): 290-294 . doi: 10.11858/gywlxb.1999.04.009

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Abstract:
The present paper has calculated the p-V-T of gas N2 at temperature 150 K and density not more than 2.548c using Beattie-Bridgeman (BB) equation of state and its modification Benedict-Webb-Rubin (BWR). It is surprisingly found that the BWR equation of state is accurate at such low temperature and rather high density. For example, the error is not more than 4.50% until 100 00 MPa of pressure, however, BB equation of state is absolutely invalid at the same condition. Therefore, BWR equation of state can represent the behavior of gas N2 at or near the critical state as well as high density state.

Study on Shock Compression of Liquids Nitrogen and Carbon Monoxide

SHI Shang-Chun, DONG Shi, HUANG Yue, LIU Fu-Sheng, SUN Yue

1999, 13(4): 295-300 . doi: 10.11858/gywlxb.1999.04.010

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Abstract:
Dynamic equation-of-state for liquids N2 and CO were measured in the shock pressure range of 10～57 GPa, using a two-stage light-gas gun. The liquids were shocked from initial states near their saturation curves at 77.6 K that their densities are about 0.808 g/cm3 and 0.807 g/cm3 for N2 and CO, respectively. The Hugoniot data of liquid N2 and CO are obtained. These results show that nitrogen has been dissociated in shock pressure above 30 GPa. And, the carbon monoxide has a chemically non-reactive compressive process in shock pressure below 20 GPa, but it has a chemically reactive complicated process in up to pressure 20 GPa. In addition, both liquids N2 and CO have the similar shock compression characteristics below 20 GPa.

Effect of Buoyant Force and Its Influence on the Process of Growing Diamond by the Excess Pressure Seed Method

LUO Bo-Cheng, LUO Xiang-Jie, ZHANG Xin-Yuan, LI Zhu, DING Li-Ye

1999, 13(4): 301-306 . doi: 10.11858/gywlxb.1999.04.011

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Abstract:
In Excess Pressure Seed Method of synthesis diamond, we have observed the phenomenon that crystal seed grew floating up in the melting metal solvent under high-temperature and high-pressure by appropriate designing the composite cavity assembly, designing the way and the location of crystal seed plant and selecting of composite condition. The phenomenon is caused by the difference of specific gravity between metal and carbon. In the experiment, a close relation is shown between the crystal seed floating up phenomenon and the composite condition. An appropriately high temperature and pressure is necessary. The effect of buoyant has some influence on the formation of the diamond polycrystalline and crystal shape in excess pressure seed method.

1999 Vol. 13, No. 4

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