首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到18条相似文献,搜索用时 406 毫秒
1.
铜的高压声速和冲击熔化   总被引:4,自引:4,他引:4       下载免费PDF全文
 用光分析技术,测量了在一维应变冲击条件下,无氧铜的高压下声速,压力范围为125~170 GPa。将上述结果与Broberg、Morris等和Aльгшуер等过去发表的数据结合在一起,对0~170 GPa整个压力区间的声速数据做了综合分析,给出了声速随压力的变化规律。实验结果发现,无氧铜在156~159 GPa之间开始发生冲击熔化,到170 GPa左右,完全进入液相区;对于处于0~156 GPa固体无氧铜的弹性声速cl可用ln cl=1.565 888-2.645 488×10-2ln p+2.710 681×10-2ln2p拟合公式描述(p的单位为GPa,cl的单位为km/s),拟合值与实验值的相对误差小于1.3%。  相似文献   

2.
 实验测量了国产聚四氟乙烯(SFB-1)在15~40 GPa冲击压力范围内的电阻率及冲击压缩线。主要的实验结果是:电阻率是冲击压力的单调递减函数,其数值在2.45×105~1.73×103 Ω•cm之间变化;冲击压缩线可用D=1.571+1.961u-0.0537u2表示(D,u分别为冲击波速度及粒子速度,单位均为km/s)。与其他作者发表的数据相比,发现不同制造厂家生产的聚四氟乙烯材料的电阻常数数值有一定的差别,但其以D-u关系表示的冲击压缩线没有出现可以察觉的变化。  相似文献   

3.
动载荷下金属板表面的微物质喷射   总被引:4,自引:4,他引:0       下载免费PDF全文
 用石英晶体传感器技术,测量了冲击波作用下铝合金(Ly-12)和纯铅样品自由表面的微物质喷射量。在冲击压力为32 GPa时,测得光洁度为3.2、0.4、0.1 μm的铝合金的微物质喷射量分别为1.53~3.28 g/m2,0.2~0.3 g/m2和0.053~0.096 g/m2,对光洁度为3.2 μm的纯铅样品,在压力为13 GPa和47 GPa时,微物质喷射量分别微26.4~42.4 g/m2和183~328 g/m2。在最高冲击压力约为20 GPa时,做了多次冲击下的微物质喷射量测量,发现比单次冲击加载下的喷射量有很大的减少。结果表明,微物质喷射量与自由表面的加工条件、局部熔化和加载方式等因素有关。  相似文献   

4.
冲击波温度和压力对二氧化钛相变的影响   总被引:2,自引:2,他引:0       下载免费PDF全文
 介绍了一种简便易行的降低疏松固体物质冲击波温度的方法,其要点是用液体石蜡充填样品的空隙。以用粉末锐钛矿压装成型的样品为例,对比了不充填和充填液态石蜡时冲击波作用的结果。在同样的冲击加载条件下(均为钢飞片,撞击速度为3.16 km/s),估算两种样品中达到的压力分别为36.3 GPa和46.8 GPa,平均温度分别约为4.7×103 ℃和2.0×103 ℃,即:充填液态石蜡的样品中压力增加了约10 GPa,但平均温度降低了近3×103 ℃。对冲击后回收样品的分析结果表明,不充填石蜡样品的主要产物为金红石,即冲击波产生的高温起了主要作用。而充填液态石蜡时,主要生成β-TiO2高压相,即高压起了主要作用。  相似文献   

5.
PbMoO4原位高压拉曼光谱和电导率的研究   总被引:2,自引:0,他引:2       下载免费PDF全文
 钼酸铅(PbMoO4)具有高的声光品质因数、低的声损耗、良好的声阻抗匹配等性质,被广泛应用于声光偏转器、调制器、可调滤光器、声表面波器件等各类声光器件,其优异的低温闪烁性能亦引起人们的注意,具有在核设备方面的应用潜力。为探讨其晶体结构和物理性质,在金刚石对顶砧上原位测量了PbMoO4的拉曼光谱,并测量了其在几个不同压力点下电导率随温度的变化。实验发现,压力在12.5 GPa时,拉曼峰完全消失,说明压力在10.8~12.5 GPa之间PbMoO4样品出现了非晶态转变。当从26.5 GPa卸压到9.4 GPa时,PbMoO4的拉曼谱在低波数出现无序化,而在2.4 GPa压力下858 cm-1峰又重新出现,说明样品结构由无序向晶化回复。压力在10.8 GPa以上时,电导率随着温度的增加而显著增加,且随着压力的增加也明显增加。  相似文献   

6.
凝聚炸药中超压爆轰的实验研究   总被引:1,自引:1,他引:0       下载免费PDF全文
 采用飞片碰撞技术,在TNT/RDX(40/60)炸药中获得了2.5倍于正常爆轰的最大超压值,得到了超压爆轰下爆轰产物物态方程p=Aρk+A1(p-pJ)(p-爆压,单位GPa,ρ-密度,单位kg/m3,A=ρJkJ,pJ=27.06 GPa,ρJ=2.3×103 kg/m3,k=2.77,A1=2.7×10-3 GPa-1,下表J代表正常爆轰状态)。该方程还可以较好地描述超压爆轰产物的二次冲击状态。  相似文献   

7.
高温高压下二辉橄榄岩的阻抗谱实验研究   总被引:6,自引:0,他引:6       下载免费PDF全文
 在1.0~4.0 GPa压力、1 073~1 573 K温度和10-1~107 Hz频率条件下,利用SARLTON-1260阻抗-增益/相位分析仪,就位测定了二辉橄榄岩的阻抗谱。实验结果表明:二辉橄榄岩的阻抗谱对频率具有很强的依赖性,并从阻抗谱的测试原理(颗粒内部、颗粒边缘、样品与电极间的导电机制)上做出了解释;温度是决定二辉橄榄岩电导率的一个重要物理参数,电导率随着温度的升高而增大,lg σ与1/T之间符合Arrenhius关系式;在高压实验中第一次将压力作为测量二辉橄榄岩电导率重要的约束因素,随着压力的增大,电阻率升高、电导率降低。  相似文献   

8.
 讨论了PDC材料烧结过程中钴在金刚石层中的固相扩散、钴液熔渗、两次钴高浓度峰的“波浪”式迁移过程中的运动规律及其作用机制,并根据实验观测的数据进行了有关计算。结果表明:在5.8 GPa、1 300 ℃条件下,钴的扩散系数D≈1.6×10-7 cm2/s,是一般常压及相同温度条件下钴固相扩散系数(3×10-10 cm2/s)和相同压力条件下钴的液相扩散系数(5×10-5 cm2/s)的中间值;对于粒度W≥10 μm的金刚石烧结体系,钴液熔渗作用时间非常短暂,略大于0.5 s,而对于W≤1 μm的超细金刚石烧结体系而言,钴熔渗作用时间为28 s,比粒度W≥10 μm的金刚石烧结要长得多;两次钴高浓度峰的迁移速度分别约为50 μm/s和100 μm/s。  相似文献   

9.
 本文采用在位的(in situ)高压X光衍射方法研究了近50 GPa和室温下三方结构NiO的等温压缩行为,并用Murnaghan状态方程对实验值进行了最小二乘法拟合,得到的NiO室温状态方程的相应参量分别为:B0=223 GPa,B0'=4.21。在室温压力范围内没有观察到第一类结构相变。NiO在六方指标下的轴比c/a随压力的变化在实验压力范围内可用c/a=2.450~1.569×10-3(GPa)近似描述。  相似文献   

10.
 本文采用金刚石对顶压砧高压装置和高压X射线技术测定了两种金属玻璃线压缩率曲线;得到Cu30Zr70和Cu25Zr75的线压缩率分别为2.7×10-3 GPa-1和2.3×10-3 GPa-1,实验最高压力超过30 GPa。实验过程中首次观察到Cu-Zr金属玻璃在室温下加压发生晶化的现象。  相似文献   

11.
In-situ high pressure Raman spectra and electrical conductivity measurements of scheelite-structure compound PbMoO4 are presented. The Raman spectrum of PbMoO4 is determined up to 26.5 GPa on a powdered sample in a diamond anvil cell (DAC) under nonhydrostatic conditions. The PbMoO4 gradully experiences the trans- formation from the crystal to amorphous between 9.2 and 12.5 GPa. The crystal to amorphous transition may be due to the mechanical deformation and the crystalographic transformation. Furthermore, the electrical conductivity of PbMoO4 is in situ measured accurately using a microcircuit fabricated on a DAC based on the van der Pauw method. The results show that the electrical conductivity of PbMoO4 increases with increases of pressure and temperature. At 26.5 GPa, the electrical conductivity value of PbMoO4 at 295K is 1.93 - 10-4 S/cm, while it raises by one order of magnitude at 430K and reached 3.33 - 10-3 S/cm. However, at 430K, compared with the electrical conductivity value of PbMoO4 at 26.5 GPa, it drops by about two order magnitude at 7.4 GPa and achieves 2.81 × 10^-5 S/cm. This indicates that the effect of pressure on the electrical conductivity of PbMoO4 is more obvious than that of temperature.  相似文献   

12.
 本文采用DAC(金刚石压砧高压腔)装置,对氧化镍进行了静水压、非静水压、电导率测量等系统高压实验,获取了氧化镍等温压缩、高压相变及电导率压力效应的新结果,并在实验数据的基础上,对其高压相变与电性及磁性变化关系及体弹性模量作了分析讨论。  相似文献   

13.
The electrical resistivity of Fe0.94O (wüstite) has been measured under shock-wave conditions to pressures between 72 and 155 GPa (0.72 to 1.55 Mbar). The resistivity of FeO at these pressures is approximately 1 (+/-0.6) × 10-6 ohm-m, as compared with 1.7(+/-0.3) × 10-3 ohm-m at ambient conditions. The absolute value of the electrical resistivity and the increase in resistivity with pressure along the Hugoniot (i.e. the shock compression curve) are consistent with FeO becoming metallic at high pressures and temperatures.  相似文献   

14.
The region of a high electrical conductivity of lithium hydride is experimentally determined in the pressure range 100–150 GPa and the temperature range 2000–3000 K of multiple shock compression. This result is used to construct thermodynamic potentials for the two polymorphic modifications of lithium hydride (B1, B2), and these potentials make it possible to calculate its thermophysical properties in the shock pressure range 80–1200 GPa. The calculated and experimental results are analyzed to determine the B1 ? B2 equilibrium line for the polymorphic modifications of lithium hydride at pressures up to 300 GPa and temperatures up to 2000 K.  相似文献   

15.
脉冲激光作用下铝靶的层裂   总被引:1,自引:0,他引:1       下载免费PDF全文
 本文报导波长为1.06 μm脉宽(FWHM)约4 ns的强脉冲激光辐照下,铝靶发生层裂的实验结果。当入射功率密度在2.0×1011~5×1011 W/cm2范围的激光束作用下,厚度为0.1 mm、0.2 mm的靶在超临界条件下发生层裂,层裂厚度分别在(17±6) μm及(35±5) μm范围。文中使用一种简化模型对阈值条件下不同厚度的靶发生层裂时的层裂片厚度作了近似估算,并与已有的实验结果较好地符合。  相似文献   

16.
Phase transitions in selenium are studied by time-resolved measurements of the electrical conductivity under shock compression at a pressure of up to 32 GPa. The pressure dependence of the electrical conductivity (σ(P)) has two portions: a sharp increase at P < 21 GPa and a plateau at P > 21 GPa. The experimental data and the temperature estimates indicate that, at P < 21 GPa, selenium is in the semiconductor state. The energy gap of semiconducting selenium decreases substantially under compression. At P > 21 GPa, the electrical conductivity saturates at ~104 Ω?1 cm?1. Such a high value of the electrical conductivity shows the effective semiconductor-metal transition taking place in shock-compressed selenium. Experiments with samples having different initial densities demonstrate the effect of temperature on the phase transition. For example, powdered selenium experiences the transition at a lower shock pressure than solid selenium. Comparison of the temperature estimates with the phase diagram of selenium shows that powdered selenium metallizes in a shock wave as a result of melting. The most plausible mechanism behind the shock-induced semiconductor-metal transition in solid selenium is melting or the transition in the solid phase. Under shock compression, the metallic phase arises without a noticeable time delay. After relief, the metallic phase persists for a time, delaying the reverse transition.  相似文献   

17.
The specific electrical conductivity Σ of water was measured during multistage shock loading to pressures of 12–130 GPa. At maximum pressure the density of the water was 3.2 g/cm3. Three or four pressure discontinuities could usually be resolved experimentally and the value of Σ was determined in each of these. As the pressure was increased in this range, the value of Σ increased from 1.2 to approximately 150 S/cm. In electro-chemical experiments, galvanic cells having electrodes of various metals and water as the electrolyte were subjected to dynamic compression. The characteristics of the recorded emf of these cells indicate that the high electrical conductivity of highly compressed water is of an ionic nature.  相似文献   

18.
Abstract

The shock adiabat for liquid xenon in the density range of 5.2–7.9 g/cm3 and pressure range of 8–70 GPa was investigated. The brightness temperature of a shock wave front from 5000 K to ?15,000 K, as well as the electrical conductivity behind the front from 4·103 to 1.2·105 1/Ohm m, were measured. X-ray technique was used to measure quasi-isentropic compression of liquid xenon up to ~13 g/cm3.

The equations of state for liquid and solid phases of xenon were found. Anomalous behavior of xenon at p=8.37 g/cm3 was revealed, that is due to a structural transition.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号