高压物理学报

LI Yong-Chi, GUO Yang, TAN Fu-Li, ZHU Lin-Fa

2003, 17(2): 81-87 . doi: 10.11858/gywlxb.2003.02.001

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Abstract:
The most materials have the positive strain-rate sensitivity, the yield stresses of which will increase with the strain-rate increasement. However, based on the dynamic experiments we found that the Al-Li alloy has the negative strain-rate sensitivity and the impact ductility. In this paper, by means of the gas gun experiments, the free-surface velocity history and other related parameters are measured, and the D-u Hugoniot curve of Al-Li alloy is obtained. The experiments reveal that under the impact loading the double wave structure similar to that in elastoplastic materials will occur in this strain-rate sensitive material, which shows that our concept about the material of limited negative strain-rate sensitivity is reasonable. Finally, under the hypothesis of weak shocks, we deduced the relationship between the D-u Hugoniot curve and the Murnagham equation, and the parameters of Murnagham equation of Al-Li alloy are obtained based on the experimental data.

Pressure and Temperature Effects on the System of Lithium Doped in Solid D2

MA Yan-Ming, CUI Tian, HE Wen-Jiong, ZHOU Qiang, LIU Zhi-Ming, ZOU Guang-Tian

2003, 17(2): 88-94 . doi: 10.11858/gywlxb.2003.02.002

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Abstract:
We employ quantum path-integral Monte Carlo method to investigate the pressure and temperature effects on the system of Li in solid D2. Our results show that under high pressure (0.9~2.4 GPa), when the lithium atom doped into solid D2, it will occupy five-vacancy trapping site. Application of temperature can not change this fact. Pressure and temperature effects on the Li atomic absorption spectrum of Li in solid D2 are similar to the results of Li in solid H2. However, at a given pressure and temperature point, the difference between the two kinds of absorption spectrum is significant. With the increase of pressure or temperature, the difference between the two kinds of absorption spectrum is getting less visible.

Correction of Temperature Gradient in Sample Cell of Pulse Transmission Experimental Setup on Multi-Anvil High Pressure Apparatus

LIU Wei, DU Jian-Guo, YU Yong, BAI Li-Ping, WANG Chuan-Yuan

2003, 17(2): 95-100 . doi: 10.11858/gywlxb.2003.02.003

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Abstract:
There is a remarkable temperature gradient in the sample cell in the pulse transmission experimental setup on a multi-anvil high pressure apparatus. The elastic wave velocity was corrected by combination of experiment, theory analysis, and computation in terms of the experimental data on temperature distribution in the sample and the linear decrease of temperature dependence of elastic wave velocities in rocks at a given temperature range. The experimental vP in amphibolite was corrected by this method and compared with the vP without correction: the absolute correction value turned greater as the temperature increased; at 530 ℃, the greatest correction of velocities in the sample X and sample Y were up to -0.270 km/s and -0.118 km/s with the decreases of 3.3% and 1.5%, respectively. This method improves the accuracy of vP measurement in high pressure and temperature experiments, which is useful to interpret geophysical data by combining the experimental results.

Effect of Pressure on Carbon Concentration in C-H-O Supercritical-Fluid

ZHAO Xian-Feng, HONG Shi-Ming, LIU Fu-Sheng

2003, 17(2): 101-105 . doi: 10.11858/gywlxb.2003.02.004

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Abstract:
By statistical thermodynamics methods and CHEQ code, the concentrations of carbon in the system of graphite-water were calculated at 5.5~7.7 GPa and 1 000~2 900 K. Relation between the concentration of carbon in water and the pressure was mainly studied. Results could be summarised as follows: (1) At a fixed pressure, there is a definite down-limit and a up-limit of temperature, between them the concentration difference of graphite and diamond in water X(C) is positive; (2) Under a definite pressure, there is a maximum of the concentration difference of graphite and diamond in water. Both of the maximum of X(C) and the temperature, which make X(C) maximum, increase with the increase of the pressure remarkably.

Analysis of Reaction Products of Micro-Crystal Mixture of Graphite Hexagonal Boron Nitride with Water under the High-Temperature and High-Pressure

LUO Xiang-Jie, PENG Fang, CHEN Hao, BI Yan, LUO Bo-Cheng, DING Li-Ye

2003, 17(2): 106-110 . doi: 10.11858/gywlxb.2003.02.005

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Abstract:
In this paper, the possibility of synthesizing the boron-carbon-nitride (B-C-N) compound by water catalyst has been investigated. The micro-crystal mixture of graphite and hexagonal boron nitride (hBN) was obtained by ball-milling. Under the temperature of 800~1 500 ℃ and the pressure of 6.1 GPa, this mixture reacted with water. By XRD and XPS, we analyzed the reaction products of the mixture with water, and found that the recrystallizing graphite formed and the crystallinity of graphite increased gradually when temperature increased, but recrystallizing hexagonal boron nitride (hBN) and cubic boron nitride (cBN) were not found. When the ball-milling was not sufficient, the XRD spectra peak of the micro-crystal mixture of graphite and hexagonal boron nitride (hBN) had not been widened sufficiently. The crystal of graphite and cubic boron nitride (cBN) were found, but the B-C-N crystal was not found.

Formation of Functionally Graded Material during the Propagation of Phase Boundary under Shock Loading

DAI Xiang-Yu, TANG Zhi-Ping

2003, 17(2): 111-116 . doi: 10.11858/gywlxb.2003.02.006

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Abstract:
The propagation of shock-induced phase boundary in a material undergoing irreversible phase transition was studied theoretically using a model based on simple-mixture rule. It was found that along with the decay of the phase boundary, the functionally graded material (FGM) formed in the mixed-phase region. Such FGMs are composed of original phase and product phase, and the composition and physical properties are changing continuously with the coordinate without apparent macro-interfaces between two phases. The effect of stress boundary conditions of impact loading on the grade and range of the FGM region was investigated in detail with a numerical method. Finally, the possibility of producing FGMs with impact method was proposed and the limit of this method has been discussed.

Shock Wave Induced by High-Energy Proton Beams

WANG Tong-Quan, ZHANG Ruo-Qi, TANG Wen-Hui, XIAO Ya-Bin

2003, 17(2): 117-121 . doi: 10.11858/gywlxb.2003.02.007

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Abstract:
The numerical simulation of the shock wave induced by intense proton beams were presented in this paper, the energy deposition process of the intense proton beams in Al were simulated by Monte Carlo method, and the coupled mechanical process induced by the energy deposition were simulated by use of one dimensional fluid-elastic-plastic model. Some results such as the energy deposition profile of the intense proton beams and the evolution of the induced shock wave were obtained.

Effect of High Hydrostatic Pressure Treatment on Physiological Characteristics of Rice Plants (Oryza sativa L.)

LI Gui-Shuang, BAI Cheng-Ke, DUAN Jun, PENG Chang-Lian, WENG Ke-Nan, LIU Shu-Dong

2003, 17(2): 122-128 . doi: 10.11858/gywlxb.2003.02.008

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Abstract:
Seeds of two rice (Oryza sativa L.) cultivars, Yuexiangzhan and Yuefengzhan, were soaked for 10 h, and then were treated by 75 MPa high hydrostatic pressure for 12 h. Germination rates decreased to 85.6% (Yuexiangzhan) and 83.4% (Yuefengzhan) relative to the untreated, and seedling rates were only 24.6% (Yuexiangzhan) and 21.9% (Yuefengzhan). Plant growth was inhibited in both treated cultivars during the early growth stage of seedling, but could exceed that of the contrast after sowing of 35 d. The seedlings of the treated and untreated were transplanted in the field after sowing of 35 d. Photosynthetic characteristics were compared between the treated and untreated during flag leaf development (55~130 d after sowing). The average values of net photosynthetic rate (Pn) and apparent quantum yield (AQY) in treated cultivars increased by 9.2% and 12.4% (Yuexiangzhan), 5.7% and 17.4% (Yuefengzhan), relative to the untreated, respectively. The total average photosynthetic pigment content was higher in both treated cultivars than their untreated during different growth stage. During leaf senescence, both Fv/Fm and pigment content decreased slowly or lately in two treated cultivars than the untreated. Consequently, the biomass and grain yield increased by 8%~27% and 7.6%~14% in both treated cultivars. Several mutated strains with different morphological and yield characteristics could be selected from treated rice plants. The results suggested that high hydrostatic pressure treatment is possible served as a new method of breeding in the future.

Shear Fractures of LY12 Aluminum Cylinder under High-Strain-Rate Implosive Loading

TANG Tie-Gang, HU Hai-Bo, LI Qing-Zhong, GU Yan, ZHANG Chong-Yu, WANG De-Sheng

2003, 17(2): 129-134 . doi: 10.11858/gywlxb.2003.02.009

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Abstract:
In this paper, the shear fracture performances of LY12 aluminum cylinder were studied under explosive loading. The recovered fragments showed shear characteristics. The fracture surface formed along the maximum shear stress curves. SEM images of the recovered fragments illustrate that the fracture surfaces have undergone friction. The adiabatic shear bands and microcracks all initiate near the inside wall and develop along the maximum shear stress curves to the outside wall of the cylinder. The histories of stress and strain from numerical calculations indicate the adiabatic shear bands initiate more easily near the inside of cylinder than in other zones, which corresponds to the results of metallographic analysis.

Estimation of Thickness of Melted Layer near Explosive Welding Interface

YAN Hong-Hao, LI Xiao-Jie, JIA Hong-Zhi, LI Hong-Sheng, XI Jin-Yi

2003, 17(2): 135-140 . doi: 10.11858/gywlxb.2003.02.010

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Abstract:
The temperature rise near explosive welding interface is caused by explosive adiabatic compression and abnormal deformation energy deposition. Through the calculation of temperature rise, the melting criterion was given, and the thickness of melted layer near explosive welding interface was estimated.

Study on the Catalytic Function of Li3N, Mg3N2, Ca3N2

XU Xiao-Wei, LI Yu-Ping, ZHAO Hong-Mei, FAN Hui-Li, ZHANG Yong-Jie

2003, 17(2): 141-144 . doi: 10.11858/gywlxb.2003.02.011

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Abstract:
It is well known that Li3N, Mg3N2 and Ca3N2 are catalysts for cBN synthesis under high temperature and high pressure. We discovered that they could also act as catalysts for hBN formation at high temperature and normal pressure. It is confirmed that, from a series comparative experiments, each of them has catalysts effect only on melting condition, the catalytic order for hBN formation is Li3NMg3N2Ca3N2, which is similar to that for cBN synthesis. The suggestion that a catalyst for hBN formation may also be a catalyst for cBN synthesis may be reliable.

Brim Effect of Negative Bias-Enhanced Nucleation of Diamond Film on Silicon Substrate

WANG Chuan-Xin, WANG Jian-Hua, MA Zhi-Bin, MAN Wei-Dong, WANG Sheng-Gao, KANG Zhi-Cheng

2003, 17(2): 145-149 . doi: 10.11858/gywlxb.2003.02.012

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Abstract:
Diamond nucleation improved by negative bias-enhanced technology on Si (100) substrate has been investigated on a microwave plasma enhanced chemical vapor deposition (MPCVD) apparatus using a gas mixture of methane and hydrogen. The results show that the bias voltage has a significant effect on the uniformity of the nucleation density and the concentration of the methane mainly relevant to the nucleation time. There is an obvious brim effect of the nucleation when the size of the silicon substrate is less than that of the Mo substrate holder. The nucleation density of the side is higher than that of the center on the substrate when the bias voltage is lower than -150 V. The nucleation density of the side decrease significantly with the bias voltage when the bias voltage is lower than -150 V. There are nearly no nuclei on the side of silicon when the bias voltage is -200 V. This effect may be contributed to the electron emission of the diamond on Mo substrate holder. The concentration of the methane has little effect on the nucleation density at a fixed bias voltage. Increasing the methane concentration is useful for decreasing the nucleation time.

Equation of State and Electric Properties of BaCuO2.5 under High Pressures

ZHANG Gong-Mu, BAO Zhong-Xing, LI Feng-Ying, LIU Cui-Xia, YU Ri-Cheng, Lü Tian-Quan, JIN Chang-Qing

2003, 17(2): 150-152 . doi: 10.11858/gywlxb.2003.02.013

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Abstract:
p-V relationship for BaCuO2.5 at room temperature and in the pressure range up to 4.5 GPa was obtained using a piston-cylinder type device. Its equation of state, Grneisen parameter 0, bulk modulus B0, and the first order pressure derivative of B0 were also acquired. The resistance versus pressure (R-p), and capacitance versus pressure (C-p) relationships up to 20 GPa were simultaneously studied using DAC at room temperature. The results showed that no phase transition occurred under pressure up to 20 GPa.

Curve-Fitting Method for Determining the Delay-Time in SHPB Experiments

XU Ming-Li, ZHANG Ruo-Qi, ZHANG Guang-Ying

2003, 17(2): 153-156 . doi: 10.11858/gywlxb.2003.02.014

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Abstract:
With the pre-determined density of specimen, the elastic velocity can be solved by the shape fitting of the predicted transmission wave with the measured transmission wave in the initial stage, and then the delay-time in SHPB data processing can be determined.

Elastic Properties of MgCNi3 Superconductor under Hydrostatic Pressure

ZHOU Bo, WANG Ru-Ju, ZHANG You-Lin, LI Feng-Ying, YU Ri-Cheng, JIN Chang-Qing

2003, 17(2): 157-160 . doi: 10.11858/gywlxb.2003.02.015

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Abstract:
Using Pulse-Echo Overlap Method, the velocities of longitudinal and shear waves of Ceramic MgCNi3 superconductor were measured up to hydrostatic pressure of 0.5 GPa. The bulk modulus B, shear modulus G, Debye temperature and specific heat under pressure were calculated. The values of Debye temperature D and specific heat cV under ambient condition are 454.82 K and 111.30 J/(molK), respectively. The B-p curve was fitted linearly to obtain B0, the first order derivative of bulk modulus at zero pressure. The Murnaghan equation of state was established.

2003 Vol. 17, No. 2

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