Quantitative Schlieren Measurement of Explosively‐Driven Shock Wave Density,Temperature, and Pressure Profiles

Shock waves produced from the detonation of laboratory‐scale explosive charges are characterized using high‐speed, quantitative schlieren imaging. This imaging allows the refractive index gradient field to be measured and converted to a density field using an Abel deconvolution. The density field is used in conjunction with simultaneous piezoelectric pressure measurements to determine the shock wave temperature decay profile. Alternatively, the shock wave pressure decay profile can be estimated by assuming the shape of the temperature decay. Results are presented for two explosive sources. The results demonstrate the ability to measure both temperature and pressure decay profiles optically for spherical shock waves that have detached from the driving explosion product gases.     

Improved phase-change properties of Sn–Zn–Sb alloys with a two-step crystallization process for multi-level data storage applications

We investigated Te-free ZnSb films for the potential applications in multi-level data storage. It was found that, the films could exhibit three phases during crystallization process, e.g., high amorphous phase, intermediate metastable ZnSb phase, and low stable ZnSb phase. However, the formation of the voids in the metastable ZnSb phase, high crystallization temperature and large amorphous resistance have an influence on the structure stability and SET power consumption during the repeated switching process. Interestingly, doping of Sn with a concentration of 11.1 at% into ZnSb can prevent the growth of metastable ZnSb grains, and different crystals like SnSb and ZnSnSb₂ can be precipitated out during heat treatment, but the two-step crystallization process is kept unchanged. Moreover, the chemical environment of Sn in Zn–Sb studied by X-ray photoelectron spectroscopy indicates the formation of the large number of Sn–Sb and Sn–Zn bonds, which in turn reduces the crystallization temperature, lowers crystallization activation energy as well as decreases the amorphous resistance. The in situ transmission electron microscopy measurements on the optimized (ZnSb)_88.9Sn_11.1 composition confirms a two-step phase transition process from amorphous to rhombohedral SnSb crystals first, and then to the stable tetragonal ZnSb₂Sn crystals. These excellent properties make Zn–Sb–Sn materials useful as a phase-change layer in low-power and high-density memory.     

JHB-1C传爆药高应变率力学行为的实验方法

利用实验测试和数值模拟相结合的手段,对传统SHPB实验方法进行了改进,研究了JHB-1C传爆药高应变率力学行为.采用半导体应变片测试技术记录低阻抗材料微弱的透射信号.通过相对校验技术消除半导体应变片的温度效应.为实现常应变率加载,对几种试样的尺寸进行了数值模拟.结果表明,试样直径为8 mm,厚度为2 mm时更适合于火炸...     

Use of Emulsion Explosives in Experimental Studies of Flows in the Bonding Zone in Explosive Welding

Bonding of steels of different hardness through a ductile layer was obtained by explosive welding using an emulsion explosive. In the bonding zone, two types of waves were found: large waves and small waves which have not been observed in previous experiments. Empirical relations for calculating the wave size are proposed that take into account the influence of the strength and density of the colliding materials on them. Cracking in the bonding zone can be avoided by reducing the wave size.     

聚乙烯醇/淀粉薄膜的力学性能及结晶行为

通过熔融共混挤出的方法,制备了聚乙烯醇(PVA)/淀粉薄膜,研究了淀粉加入量对PVA/淀粉薄膜力学性能的影响。采用差示扫描量热法研究了PVA薄膜和PVA/淀粉薄膜的结晶行为及非等温结晶动力学。结果表明:随着淀粉含量的增加.PVM淀粉薄膜的拉伸强度和断裂伸长率下降。在淀粉质量分数为25%时,薄膜的拉伸强度为17.05 MPa.断裂伸长率为425.00%.仍能达到包装薄膜对力学性能的要求。PVA/淀粉薄膜熔融温度和结晶温度均随着淀粉加入量的增加向低温方向移动;在相同的冷却速率下,共混薄膜的结晶速率低于PVA薄膜,同时结晶度也下降.导致力学性能下降。     

丙烯酸改性卤锑阻燃聚丙烯的结晶性能

研究了丙烯酸(AA)改性Sb2O3,聚丙烯(PP)母料制备的不同用量卤锑阻燃PP。阻燃PP的差示扫描量热法结果表明,阻燃剂在PP中存在明显的异相成核作用,使PP结晶温度提高,Sb2O3对PP的异相成核作用比十溴二苯醚明显。在无引发剂过氧化二异丙苯(DCP)存在下,AA对阻燃PP中PP结晶温度的影响取决于阻燃剂的用量;在DCP存在下,PP的结晶温度不随AA用量增加而改变。DCP用量增加导致PP严重降解,结晶温度与熔融温度降低。     

SnO2:Sb透明导电薄膜的制备及光电性能

采用溶胶–凝胶法在玻璃基底上制备了Sb掺杂SnO2（SnO2：Sb）透明导电薄膜。研究了Sb掺杂量、镀膜次数、热处理温度对SnO2：Sb薄膜结构和光电性能的影响,利用X射线衍射仪、Fourier变换红外光谱仪、扫描电子显微镜、四探针电阻仪、分光光度计对薄膜样品进行表征。结果表明：SnO2：Sb薄膜为四方相金红石结构;薄膜结构平整、致密,膜厚与镀膜次数基本成线性关系;在Sb掺杂量为10%,镀膜8次的条件下,薄膜具有最佳的光电性能,方块电阻达105/□;在玻璃上镀SnO2：Sb薄膜后,近红外波段透过率下降显著,由90%降到5.5%,在可见光波段略有降低,仍保持了较高透过率。     

Shock Profiles Along a Specimen

The observation of shock waves in a block of plexiglass caused by a detonating high explosive charge shows the influence of air-gaps and cover-plates which are attached head on. The shock wave for high explosive charges without any cover plate gives a high maximum pressure which decays quickly. The detonating high explosive charge which is covered with a two millimeter thick disc of copper shows a shock wave which is constant over a certain time. An air-gap between the high explosive charge and the measuring plexiglass block always gives a weak shockwave at the beginning. In the case of an uncovered high explosive charge the expansion of the high explosive products gives a relatively smooth increasing blast or shock wave, and in the case of a covered high explosive charge a strong shock resulting from the following impact of the flying plate.     

应用二维黏性CE/SE方法模拟挡波墙对爆炸流场的影响

应用高精度的二维黏性CE/SE方法模拟爆点周围有挡波墙的爆炸流场,分析了挡波墙与冲击波相互作用的规律,得到了能够反映波系结构变化的压力等值线图.数值计算结果显示了冲击波遇挡波墙发生反射、绕流等现象;通过与无挡波墙时的爆炸流场对比,分析了挡波墙的削波作用;同时考察了挡波墙的高度、厚度对远场压力的影响.数值计算结果对于爆炸流场的防护具有理论指导意义.     

Effect of Ce, Sb, and Sn on Solarization and Crystallization of an X-Ray-Irradiated Photosensitive Glass

The effect of Ce, Sb, and Sn photosensitive elements, individually and in combination with each other, on solarization and crystallization of an X-ray irradiated and a nonirradiated lithium silicate-based glass were investigated. According to the results, considering the crystallization behavior of the nonirradiated glasses, they were divided into Ce-bearing and Ce-free groups, in which the former group showed a clearer solarization tendency that manifested as an appearance of an absorbance peak at 318 nm in the spectrophotometry experiment. However, the results showed that in the irradiated glasses, the presence of Sb was more important in terms of improvement in crystallization view. Antimony decreased the differential thermal analysis (DTA) crystallization peak temperature from 655°C to 594°C and, in combination with the two other elements, changed the surface crystallization mechanism to a bulk one. The reactions that seemed to be responsible for the above-mentioned observations were discussed by spectrophotometry, DTA, X-ray diffraction, and scanning electron microscopic methods.     

Interactions of Impact Shock Waves in a Thin-Walled Explosive Container. I. Impact by a Flat-Ended Projectile

Interaction of impact shock waves that could detonate an explosive (Composition B) confined in a thin-walled container impacted by a cylindrical projectile is numerically studied, based on the Forest Fire explosive reaction rate model. After the impact, rarefaction waves from projectile periphery and front cover–explosive interface catch up the forward-moving shock fronts in the explosive as well as in the projectile. At a high impact velocity, the transmitted shock front induces detonation at the front cover–explosive interface. At an intermediate velocity, the rate of energy release from the shock-compressed volume in the explosive is such that the associated effects prevail over the effects caused by rarefaction waves, leading to detonation after the shock wave travels a certain distance in the explosive. There is a range of minimum impact velocities at which the effect of rarefaction waves prevails over the energy release; hence, the detonation is excited not behind the shock-wave front moving over the explosive but only after shock-wave reflection from the high-impedance back plate. It is suggested that, in interpreting the detonation behavior of an explosive confined by a high-impedance container, one should take into account the effects of shock-wave interaction with container walls.     

Explosion of a cylindrical charge above a rigid surface

We investigated the explosion of a cylindrical charge, which lies on a rigid surface or is positioned at some height above it. The explosion is modeled by the jump between the background and the region occupied by gas at a high pressure, density, and temperature. In an analogous formulation, the explosion from the Tunguska meteorite impact [1–4] was modeled by spherical and cylindrical explosive waves which consider the gravitational back pressure. Explosions from charges with nontraditional shapes have been studied [5–8]. Reflections of an explosive wave from a point charge from a rigid surface have been examined [9–10]. A more complete review of investigations on the spatial effects of forming propagating explosive waves can be found in [11].Moscow. Translated from Fizika Goreniya i Vzryva, Vol. 27, No. 6, pp. 131–134, November–December, 1991     

不同催化体系所得聚酯的等温结晶研究

用DSC法对三氧化二锑 (Sb2 O3)、氟钛酸钾 (K2 TiF6 )、钛酸四丁酯 (Ti(OC4 H9) 4)及乙二醇锑(S -2 4) 4种催化体系所得聚酯进行等温结晶研究 ,求得了结晶速率常数 (k)和Avrami指数 (n)。结果表明 ,锑系催化剂所得聚酯的结晶速度总体大于钛系催化剂所得聚酯 ,其中以Sb2 O3催化所得聚酯结晶速度最快 ,而Ti(OC4 H9) 4催化所得聚酯结晶速度最慢。DTA结果表明锑系催化剂所得聚酯冷结晶温度低于钛系催化剂所得聚酯 ,与结晶速度测试结果相一致。     

Initiation of detonation in explosives on an U-70 proton accelerator

Detonation initiation in a composite explosive based on HMX and TATB loaded by a divergent shock wave was studied on a U-70 proton accelerator using proton radiography. Density distributions behind the initiating shock front at various times were obtained. Detonation failure due to collision of shock and detonation waves was studied for a plastic-bonded TATB sample using radiography. Characteristic features of the explosive transformation under shock-wave loading were determined from the images obtained.     

Crystallization of Amorphous Antimony at Room Temperature: Non-Uniqueness of Patterning Route

Room-temperature crystallization of ‘explosive’ amorphous antimony was found to exhibit the phenomenon of non-uniqueness: it may spontaneously proceed (in identical samples) either within 27 days or within 67 days to yield crystallites with different preferential orientation. Apparently, this happens due to structural fluctuations in the initial amorphous matter, whereas the formation of different textures is governed by the minimization of surface energy. The phenomenon may turn useful for regulating a structure of Sb compounds in advanced semiconducting materials.     

Composition Effects on Thermal and Crystallization Properties of Glasses in Sb–S–I System

The effect of composition variations on thermal and crystallization properties of Sb–S–I glass system is investigated by differential thermal analysis (DTA) and X-ray diffraction (XRD). In general, the glass transition temperature ( T _g) and the temperature corresponding to the maximum crystallization rate ( T _p) are found to decrease with increasing iodine concentration for a fixed Sb/S ratio. However, precipitation of SbSI phase is sensitive to the Sb/S ratio for a given iodine fraction. The optimal composition and its devitrification behavior for forming only the ferroelectric SbSI phase are established on the basis of DTA curves and XRD patterns.     

Investigation of the effect of the structure of large-area carbon nanotube/fuel composites on energy generation from thermopower waves

Thermopower waves are a recently developed energy conversion concept utilizing dynamic temperature and chemical potential gradients to harvest electrical energy while the combustion wave propagates along the hybrid layers of nanomaterials and chemical fuels. The intrinsic properties of the core nanomaterials and chemical fuels in the hybrid composites can broadly affect the energy generation, as well as the combustion process, of thermopower waves. So far, most research has focused on the application of new core nanomaterials to enhance energy generation. In this study, we demonstrate that the alignment of core nanomaterials can significantly influence a number of aspects of the thermopower waves, while the nanomaterials involved are identical carbon nanotubes (CNTs). Diversely structured, large-area CNT/fuel composites of one-dimensional aligned CNT arrays (1D CNT arrays), randomly oriented CNT films (2D CNT films), and randomly aggregated bulk CNT clusters (3D CNT clusters) were fabricated to evaluate the energy generation, as well as the propagation of the thermal wave, from thermopower waves. The more the core nanostructures were aligned, the less inversion of temperature gradients and the less cross-propagation of multiple thermopower waves occurred. These characteristics of the aligned structures prevented the cancellation of charge carrier movements among the core nanomaterials and produced the relative enhancement of the energy generation and the specific power with a single-polarity voltage signal. Understanding this effect of structure on energy generation from thermopower waves can help in the design of optimized hybrid composites of nanomaterials and fuels, especially designs based on the internal alignment of the materials. More generally, we believe that this work provides clues to the process of chemical to thermal to electrical energy conversion inside/outside hybrid nanostructured materials.     

Radiographic study of interaction of shock and detonation waves in a high explosive

Collisions of shock and detonation waves in an HMX-based high explosive are experimentally studied with the use of flash radiography. Based on X-ray patterns, specific features of the wave-interaction process are identified, and qualitative differences are found in detonation formation and evolution in an explosive precompressed by a weak shock wave and in an undisturbed explosive. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 3, pp. 132–138, May–June, 2007.     

大板实验中TATB基炸药爆轰波的传播特征

为研究点起爆条件下TATB基炸药爆轰波传播特征,用双灵敏度激光速度干涉仪(VISAR)对TATB基炸药进行了大板实验研究,并用DYNA2D程序对实验进行了模拟计算.结果表明,大板实验中TATB基炸药爆轰波传播过程中的压力剖面具有"二维结构",且爆轰波传播方向由轴线方向逐渐向半径方向转变.实测铜飞片自由面的速度与计算值相吻合.     

Failure Waves in Glass

Failure waves have been recently observed in glass plates and rods struck by high-speed projectiles. These waves propagate into material that has been prestressed by a compressive shock. The wave propagation speed exceeds the maximum crack speed and is not constant. Behind the failure wave there is a total loss of tensile strength and a substantial drop in shear strength. The failure is explosive, leading to radial expansion in unconfined targets and presurization in confined targets.