高压物理学报

Shock Temperature Measurements for Metals－Release Approximation at the Interface

TAN Hua

1996, 10(3): 161-169 . doi: 10.11858/gywlxb.1996.03.001

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Abstract:
In radiometry measurements of shock temperatures for metals, release processes occurring at the metal/window interface affect substantially the final state of the tested sample, especially when release-induced melting happens. In this paper, the author describes in detail how to use a super-heating release model to evaluate the release temperature and volume of the final state when release melting occurs. Typical results for Fe/Al2O3 and Fe/LiF configurations are presented by using this model at pressures up to 270 GPa.

Synthesis of Boron-Rich Boride NdB6 under High Pressure and High Temperature

ZHAO Xu-Dong, LIN Feng, LIU Xiao-Yang, HOU Wei-Min, LIU Wei-Na, SU Wen-Hui

1996, 10(3): 170-175 . doi: 10.11858/gywlxb.1996.03.002

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Abstract:
A new route is reported to prepare boron-rich rare-earth boride NdB6 under extreme of high pressure and high temperature conditions, i.e. oxidizing amorphous elemental boron with rare-earth oxide Nd2O3. Products are analyzed by X-ray powder diffraction. Results show that the pure phase of NdB6 is obtained under the condition of Nd∶B=1∶6, 4.0 GPa, 1 600 ℃ and 15 min. The method to prepare NdB6 under high pressure and high temperature has many advantages such as easy acquiring in reaction conditions, short reaction time and pure phase of the product ect. The results of XRD indicate that the crystallized product in cubic symmetry has lattice constant a=0.417 nm.

The X-Ray Diffraction Studies of -Fe2O3 Ultrafine Particles Treated by High Pressure

LI Hai-Bo, ZHENG Wei-Tao, GONG Jie, ZUO Yun-Tong, YU Rui-Huang

1996, 10(3): 176-181 . doi: 10.11858/gywlxb.1996.03.003

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Abstract:
-Fe2O3 ultrafine particles were prepared with precipitation method and treated by high pressure at various temperatures. The samples were studied by X-ray, TEM and Mossbauer spectroscopy. The results indicate that the high pressure has no obvious influence on the size of microcrystals at room temperature, but the grain size of microcrystals increase greatly at the condition of 4.0 GPa and 400 ℃. Also, the high pressure mainly influences the orientation and lattice distortion of microcrystals.

The Luminescence Properties and High Pressure Research of LaOBr:Tb3+, Dy3+

YANG Jing-Hai, LI Yong-Ji

1996, 10(3): 182-189 . doi: 10.11858/gywlxb.1996.03.004

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Abstract:
The rare earth luminescence materials LaOBr:Tb3+, Dy3+ were synthesized at high temperature, and were treated by high pressure (HP) combined with high temperature (HT). The luminescent properties of the samples before and after HP and HT treatment were studied. The results show that codoping Dy3+ makes the luminescence strength increased greatly, and energy transfer takes place between Tb3+ and Dy3+.

Experimental Investigation of a Contactless Coilgun for 60 mm Projectiles

GAO Shun-Shou, SUN Cheng-Wei, CHEN Ying-Shi, DAI Ying-Min, WANG Min-Hua

1996, 10(3): 190-198 . doi: 10.11858/gywlxb.1996.03.005

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Abstract:
A contactless coilgun for 60 mm projectiles has been designed, fabricated and tested, which can accelerate l kg projectiles from rest to 60 m/s. The basic coilgun configuration and control system are described. Comparison between test results and computer code predictions are presented. The device provides a useful test means for launcher components and diagnostics.

Shock Activation and Modification of PZT-95/5 Piezoceramics

LIU Li, HAN Jun-Wan

1996, 10(3): 199-208 . doi: 10.11858/gywlxb.1996.03.006

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Abstract:
This paper is about shock activation and modification of PZT-95/5 ceramics. The shock loading experiments of PZT-95/5 powder and block samples show that: in suitable conditions, the density (), piezoelectric strain constant (d33) and dielectric constant () of the samples can be increased and dielectric lost coefficient (tg %) be reduced. The results of X-ray diffraction, Scan Electronic Microscope and Transmission Electronic Microscope measurement are also given. It is concluded that the mechanism of activation can be attributed to pulverization of crystallites, crystal boundary damage, microcracks, defects increase and phase changed etc.

Research on X-Ray Radiation Field Which Is from a Outer Space Nuclear Explosion

WANG Shang-Yi, ZHANG Ruan-Yu, CHEN Le-Shan

1996, 10(3): 209-214 . doi: 10.11858/gywlxb.1996.03.007

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Abstract:
X-ray is regarded as the main damage factor of nuclear interception in outerspace. A mathematical mode of X-ray radiation field which is from a nuclear explosion is needed in the spacecraft radiation damage calculation. According to Planck blackbody spectrum, we proposed a compound mode of normolized blackbody spectrum which was stratificed on the basis of temperature gradient, obtained the release energy and radiation pulse and found a mathematical mode of X-ray radiation field which is from a nuclear interception in outer space.

Geometrical Statistics and Fractal Method for the Fragment Distribution of Dynamic Loading

ZHANG Guan-Ren

1996, 10(3): 215-219 . doi: 10.11858/gywlxb.1996.03.008

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Abstract:
In this paper, two statistical Methods for the fragment distribution of dynamic loading are introduced. The one is the Mott formula generalized by Grady and Kipp, the other is the fractal method. The author has proved that the two methods are in agreement with each other, that the latter can be deduced from the former. The physical essences of the two methods are described.

Optic Radiations and Chemical Reactions in Bromoform under Shock Compressions

HU Jin-Biao, TAN Hua, JING Fu-Qian

1996, 10(3): 220-226 . doi: 10.11858/gywlxb.1996.03.009

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Abstract:
Multi-channel optic pyrometer was used to observe shock temperatures of bromoform in the pressure range from 37 to 85 GPa and thermal relaxation behavior at bromoform/sodium chloride crystal interface. The radiation time histories from shocked bromoform exhibit a two-step structure as the pressure reaches 46 GPa or higher, which return to the usual one-step profile as the pressure goes up to 85 GPa. The observed shock temperatures agree well with the reported data at pressures less than 50 GPa; at pressures higher than 76 GPa, it increases abruptly. Based on the above results and the thermal relaxation behavior at CHBr3/NaCl interface, we proposed a time-delayed exothermal chemical reaction model to describe the shock compression process occurring in bromoform under shock pressure from 46 to 85 GPa.

Phase Transition of Pb0.8Sn0.2Te Crystal under High Pressure

GU Hui-Cheng, CHEN Liang-Chen, BAO Zhong-Xing, LI Feng-Ying

1996, 10(3): 227-230 . doi: 10.11858/gywlxb.1996.03.010

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Abstract:
Phase transitions of Pb0.8Sn0.2Te crystal have been observed by X-ray powder diffraction technique with a diamond anvil cell (DAC) at pressures up to 25.2 GPa. At ambient pressure, Pb0.8Sn0.2Te crystal has fcc structure. Based on our experimental results, we observed that there exist two phase transitions in Pb0.8Sn0.2Te crystal. One appears at the pressure of 6.1 GPa, and the other at the pressure of 14.9 GPa. The former phase transition is concerned with metallization of Pb0.8Sn0.2Te crystal. Both phase transitions are reversible.

Hydrodynamics Calculations of the Fast Shock Tube Drived by High Explosive

LIU Er-Yan, YUAN Xian-Chun, LIAO Zhen-Min

1996, 10(3): 231-235 . doi: 10.11858/gywlxb.1996.03.011

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Abstract:
A phased implosion in a cylindrically high explosive (HE) shell can form extremely high pressures and energy densities in a low-density foam core within shell. In a properly designed system, the flow of compressed foam approaches a steady state nozzle flow with the same velocity as that of detonation. The propagating wave decouples from the flow behind the sonic point. The flow can be used to produce shockless acceleration of masses to hypervelocities. The numerical simulations show the formation of the axial shock from the start to its approaching of its steady state, which is in good agreement with the theoretical analysis.

Study on Diamond Film Deposition Growth on Stainless Steel Using Gas Source of CH3OH/H2

ZHANG Xiao-Ping

1996, 10(3): 236-240 . doi: 10.11858/gywlxb.1996.03.012

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Abstract:
By means of microwave chemical vapor deposition (MWCVD) method, CH3OH/H2 gas mixtures are used as a gas source, along with a 30 nm amorphous thick silicon as a transition layer, a diamond film can successfully be grown on a stainless steel substrate, with a lowest growth temperature of 420 ℃. Tests show that the joint strength between the diamond film and the stainless steel substrate is high enough to be used as a wear-resisting layer in industry.

1996 Vol. 10, No. 3

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