高压物理学报

Studies of the Explosion Expanding-Fracture Process of a Thin Cylindrical Shell

FENG Jia-Bo, JING Fu-Qian, SU Lin-Xiang, HAN Jun-Wan

1988, 2(2): 97-103 . doi: 10.11858/gywlxb.1988.02.001

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Abstract:
A damage-level function for describing the dynamic failure growth process is proposed in this paper. Starting from this function and using the hardening-viscoplastic constitutive equation as the material characteristic equation, analytical expressions of complete-fracture criterion of a thin cylindrical shell subjected to explosion expanding have been obtained under two approximate conditions (constant expanding velocity or constant strain rate). The analytical reslts demonstrate that there exists a maximum complete-fracture strain at an appropriate strain rate, which is called plastic peak. As an example, the results for mild steel indicate that the complete-fracture criterion derived in this article could be better to explain the experimental results given by Иванов and Chen et al. The complete-fracture plastic peak is nearly located at the point of strain rate e'*=4104 s-1 and strain *=60%~80%.

Investigations on the Problem of Interface Binding in the Sintering System of Diamond at High Pressure and a New Type Polycrystalline Diamond

SHEN Zhu-Tong, SUN Guo-Xian, CHI Yong-Qian, LI De-Zhen

1988, 2(2): 104-112 . doi: 10.11858/gywlxb.1988.02.002

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Abstract:
Investigations were made on the theory and experiments relating to the sintering mechanism of diamond with dopant at high pressure. In considerating of the doping and dimension effects a universal equation of Laplace second law and the interface binding characteristic equation in the sintering system of diamond were obtained. Some results of the experiment and analysis on the behaviour of diamond and dopant at high pressure were reported. Based on those results, a new type polycrystalline diamond with a special interface structure was obtained. It shows its superiority in the application to the wiredrawing die, especially the end product wiredrawing die. The uses of the diamond are being extended.

Gasket Problem in the Ultrahing-Pressure Apparatus

NIE Chong-Li, CHEN Qi

1988, 2(2): 113-118 . doi: 10.11858/gywlxb.1988.02.003

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Abstract:
For the belt type high pressure apparatus, this paper has improved the flat model of O. Fukunaga by introducing the half-angle of the tapered anvil and calculated the pressure in the gasket as well as the supporting force of the gasket to the anvil. The calculated results agree with the experimental results quite satisfactorily. The matching between the pressure increments of gasket and pressure cell has been discussed for both belt type and cube type high pressure apparatus. This paper also explained how Murnaghan equation could be used to solve the problem connected with the unloading.

Theoretical and Experimental Studies of the Dynamic Process of Thermal Expansion

ZHOU Ben-Lian

1988, 2(2): 119-122 . doi: 10.11858/gywlxb.1988.02.004

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Abstract:
The exact solutions of a set of non-linear differential equations with limiting conditions describing the anharmonic vibration of a one-dimensional lattice have been obtained. The thermal expansion coefficient of the lattice and the characteristic time of thermal expansion process were found and physical interpretations given. Some experimental results of thin metal foils could be taken as an evidence for the theoretical prediction. These results also tell us that, for high-speed heating, thermal stress exists even in the case of uniform temperature and free expanding, though it relaxes rapidly.

Mossbauer Effect Studied in the Double Rare-Earth Oxides LnEuO3

ZHAO Xin, SU Wen-Hui, XU Wei-Ming, LIU Xiao-Xiang, JIN Ming-Zhi, WU Dai-Ming

1988, 2(2): 123-130 . doi: 10.11858/gywlxb.1988.02.005

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Abstract:
For the first time, the double rare-earth oxides LaEuO3, PrEuO3, NdEuO3, SmEuO3 were synthesized by using high pressure and high temperature method. The analyses of X-ray diffraction show that LaEuO3 is A-type (hexagonal) structure; PrEuO3, NdEuO3 and SmEuO3 are of B-type (monoclinic) structure; CeEuO3.5 is of F-type (fluorite) structure. Mossbauer spectra were measured using the 21.6 keV -ray of 151Eu at room temperature. It has been observed that the hyperfine interactions depend strongly on the ligand volume of Eu ions. This volume effect of the isomer shift can be mainly attributed to the distortion of 5s shell of Eu ions.

Gauge Field Theory of Structural Transitions

WANG Ke-Gang, DONG Lian-Ke, LONG Qi-Wei

1988, 2(2): 131-136 . doi: 10.11858/gywlxb.1988.02.006

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Abstract:
From the viewpoint of gauge field theory, we have constructed the Lagrangian function of perfect crystal－the Lagrangian function of phonon field. Because of the break of symmetry of phonon field under the local group G=SO(3) we could introduce the gauge field of defects. With the aid of the spontaneous symmetry break of vacuum state and gauge field theory of defects, this paper presents the formulae of transition temperature c, jump quantity of Cv at transition Cv and order parameter i respectively. From these formulae, we can easily show the effect of defect on structural transition. Therefore, defect has been naturally introduced into the study of structural transition, and the mechanism of structural transition has also been discussed. Finally, we determined the coupled constant g of gauge field theory of defects.

Investigation on the Match of Ferroelectric Explosive-Electric Transducers

LIN Qi-Wen, YUAN Wan-Zong, WANG Wei-Jun

1988, 2(2): 137-145 . doi: 10.11858/gywlxb.1988.02.007

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Abstract:
In this paper, according to electric response theory of shock loaded PZT ferroelectric ceramic materials, we have discussed the optimal match of rectangular/cylindrical ferroelectric ceramic samples with inductance load in normal mode, some characters of the transducers under the optimal match state and its design method. Examples in the calculation show that theory is in good accordance with the experimental results of the rectangular type.

A Dynamic Measurement Study of Resistance in Synthesis Process of CeTbO3 under High Pressure and High Temperature

LIU Hong-Jian, SU Wen-Hui, QIAN Zheng-Nan, WANG Yi-Feng, WU Dai-Ming, CUI Shuo-Jing

1988, 2(2): 146-152 . doi: 10.11858/gywlxb.1988.02.008

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Abstract:
The resistance of oxides CeTbO3, CeO2, Tb4O7 and mixture CeO2+Tb4O7 (Ce∶Tb=1∶1) has been measured from room temperature to 800 ℃ at 4.0 GPa and 0.5 GPa. All of them show semiconducting character of resistance. The up-and-down changes of the mixture and Tb4O7 have been found at 0.5 GPa above 600 ℃. X-ray diffraction shows that corresponding to this change, there is a change on the structure which might closely relate to the valence fluctuation from Tb4+ to Tb3+.

A Practical EOS of Elastic-Plastic Fluid (Ⅱ)

LI Mao-Sheng, CHEN Dong-Quan

1988, 2(2): 153-158 . doi: 10.11858/gywlxb.1988.02.009

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Abstract:
As a sequel to A Practical EOS of Elastic-Plastic Fluid (Ⅰ), the paper presents the formulas for estimating dynamic yield strength and dynamic fracture strength.

Heat Treatment and Sinter of Oxide Superconductors under High Pressure

HUANG Xin-Ming, CUI Chang-Geng, CHEN Hong, XU Xiao-Ping, HE Shou-An, WANG Wen-Kui

1988, 2(2): 159-164 . doi: 10.11858/gywlxb.1988.02.010

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Abstract:
The well-known oxide superconductors were treated or sintered under high pressure and high temperature. It is found that the Tc of superconductors of SrLa(CuAg)1Ox sintered at ambient had been increased from 20 K to 28 K after some heat treatment under high pressure. However the Tc has not been increased in oxide sample of Y1Ba2Cu3O7- for both samples high pressure-sintered and heat treated under high pressure, the latter was pre-sintered in air. Nevertheless, these samples sintered at 2.0 GPa have higher microhardness and density, and their lattice parameters were changed.

Preliminary Experiments on the Equation of State of Materials at High-Pressure Produced by Laser Driven Shock Waves

GU Yuan, WANG Yong-Gang, MAO Chu-Sheng, NI Yuan-Long, WU Feng-Chun, MA Min-Xun

1988, 2(2): 165-170 . doi: 10.11858/gywlxb.1988.02.011

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Abstract:
In order to get the equation of materials, the measurements of the ablation parameters and the laser driven shock waves in aluminium targets were carried out. These results are reported in this paper.

A High Speed Schlieren System for Observing the Mass-Ejection Events from Shocked Metallic Free Surface

TAN Xian-Xiang, HUANG F

1988, 2(2): 171-173 . doi: 10.11858/gywlxb.1988.02.012

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Abstract:
A Transmission-type high-speed schlieren system suited for shock wave studies is developed in this paper. Photos of mass-ejection phenomena from shocked free surfaces of both lead and steel samples were recorded clearly by using this instrument.

Explosive Consolidation of RSHS Aluminum Alloy Powders

ZHANG Deng-Xia

1988, 2(2): 174-178 . doi: 10.11858/gywlxb.1988.02.013

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Abstract:
Dynamic consollidation by explosive detonation has been applied to rapidly solidified high strength aluminum alloy powders. Dense, uniform and defect-free cylinder compacts of 2060 mm were produced. Analysis of the microstructure shows that most particles possess good interparticle bonding and the microstructure within particle remains initial character.

Compressibility and Phase Transition of Amorphous Carbon at High Pressure

BAO Zhong-Xing, GU Hui-Cheng, ZHANG Zhi-Ting

1988, 2(2): 179-181 . doi: 10.11858/gywlxb.1988.02.014

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Abstract:
The p-V relationship of amorphous carbon up to 4.5 GPa has been studied in this article. The experimental result indicated that a phase transition occurs in this pressure range.

Criteria of Thresholds for Plasma and LSD Wave Ignition

YUAN Gang, ZHOU Guang-Quan

1988, 2(2): 182-191 . doi: 10.11858/gywlxb.1988.02.015

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Abstract:
Based on the theory of LSC and LSD waves and the experiment results the criteria of thresholds for plasma and LSD wave ignition are proposed. The pressure history on the target surface can be conveniently calculated by the criteria.

1988 Vol. 2, No. 2

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