Titanium hydride (TiH2), a promising high-energy additive, is doped into PTFE/Al to optimize the energy output structure of the reactive jet and strive for better aftereffect damage ability to the target. Six types of PTFE/Al/TiH2 reactive liners with different TiH2 content are prepared by the molding and sintering method. The energy release characteristics of PTFE/Al/TiH2 reactive jet are tested by the transient explosion energy test, and are characterized from pressure and temperature. The reaction delay time, pressure history, and temperature history of the energy release process are obtained, then the actual value of released energy and reaction efficiency of the reactive jet are calculated. The results show that the peak pressure and temperature of the PTFE/Al/TiH2 jet initially increase and then decrease with increasing TiH2 content. When the TiH2 content is 10%, the actual value of released energy and reaction efficiency increased by 24% and 6.4%, respectively, compared to the PTFE/Al jet. The reaction duration of the reactive material is significantly prolonged as the TiH2 content increased from 0% to 30%. Finally, combined with the energy release behaviors of PAT material and the dynamic deformation process of liner, the enhancement mechanism of TiH2 on energy release of the reactive jet is expounded.

A ternary system of PTFE/Al/Bi2O3 is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material. The effects of Bi2O3 in the PTFE/Al/Bi2O3 on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry, adiabatic oxygen bomb test and split Hopkinson pressure bar test. The microstructure observed through scanning electron microscope and X-ray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi2O3. The results indicate that the PTFE/Al/Bi2O3 are capable of triggering the exothermic reaction of molten PTFE/Bi2O3 and Al/Bi2O3 over the PTFE/Al reactive materials, thereby promoting reactions. The excessive aluminum in the ternary system is beneficial for increasing energy release. The ignition of shock-induced chemical reactions in PTFE/Al/Bi2O3 is closely related to the material fracture. The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.

针对反跑道弹药战斗部对机场跑道内爆毁伤效应评估的需求,为系统开展机场跑道在装药内爆载荷作用下的毁伤效应研究与构建工程函数模型,在量纲分析的基础上开展不同装药质量、不同装药埋深下的机场跑道内爆毁伤实验和数值仿真,探究装药量和装药埋深对机场跑道毁伤形态以及毁伤场参数的影响规律.研究结果表明:装药量一定时,有效毁伤半径Red随装药埋深的增加呈先增大、后减小的趋势;装药埋深一定时,毁伤效应参量随装药量的增加而增大;装药量和装药埋深的最适匹配可达到理想的毁伤效果.基于实验与数值仿真研究获得的弹坑形态和裂纹特征与跑道内爆炸作用机理分析,提出将毁伤模式和毁伤场特征参量相结合的评估方法来有效表征多层混凝土介质内爆毁伤效应,采用敞坑、隆起和隐坑3种毁伤模式来描述跑道的破坏形态,采用特征参量弹坑半径Rc、有效毁伤半径Red、最大爆腔半径Ric,以及弹坑深度H定量描述跑道内爆毁伤场区域;结合大量仿真和实验数据拟合得到机场跑道内爆毁伤模式和毁伤场特征参量的工程化函数模型,可对机场跑道内爆毁伤效应进行快速预测.

为研究Al粒径对50％:50％质量比的富铝聚四氟乙烯基铝(PTFE/Al)活性材料在中高应变率下的冲击反应行为的影响,采用模压烧结成型法制备了50 nm、10μm、70μm、200μm 4种Al粒径的PTFE/Al活性材料试件.基于分离式霍普金森压杆(SHPB)实验,利用高速摄像机拍摄不同应变率加载下PTFE/Al活性材料的冲击反应过程,分析Al粒径对PTFE/Al活性材料的冲击反应特性影响.实验结果表明:随着Al粒径从50 nm增加到10μm,反应延迟时间增加可达40％,反应持续时间降低可达17％,同时PTFE/Al活性材料参与反应的量逐渐减少,反应激烈程度和能量释放不断降低,反应难以持续进行;当Al粒径增加到70μm时,难以在SHPB加载下发生反应;加载应变率对PTFE/Al活性材料的反应性能也有较大的影响,PTFE/Al活性材料的反应延迟时间随着加载应变率的提高而降低;加载应变率和Al粒径对PTFE/Al活性材料的冲击反应扩散、反应速率、反应程度均有较大影响,可通过调节Al粒径来调节其冲击反应性能.

To obtain the influence of the Bi2O3 particle content of a PTFE/Al/Bi2O3 reactive material (later referred to as PAB) on its shock-induced chemical reaction (SICR) characteristics, five kinds of PAB with different Bi2O3 contents were prepared; the reaction process in a drop-hammer test, recorded using a high-speed camera, was analyzed. The ignition and reaction mechanisms of PAB under mechanical impact were analyzed based on the thermochemical reaction characteristics and the microstructure. The results show that with an increase in Bi2O3 content, the shock-induced chemical reaction duration and the sensitivity of PAB increase, and then decrease. When the Bi2O3 content is 9%, the impact sensitivity is the highest and the reaction duration is the longest. The heating at the crack tip is responsible for PAB ignition under long-pulse low-velocity impact. During ignition, PAB undergoes several physicochemical changes such as the melting of PTFE, a PTFE/Bi2O3 reaction, an Al/Bi2O3 reaction, pyrolysis of the melted PTFE, and a C2F4/Al reaction; moreover, the presence of Bi2O3 decreases the excitation threshold of the reactive material, which facilitates the propagation of the reaction and improves the degree of the reaction and overall energy release of the reactive material.

Polytetrafluoroethylene (PTFE)/Al reactive material with different aluminum particle sizes were prepared by molding and sintering, and the effect of aluminum particle size on the impact behavior of PTFE/Al reactive material with a mass ratio of 50:50 was investigated. The results show that aluminum particle size has significant effects on the shock-reduced reaction diffusion, reaction speed, and degree of reaction of the PTFE/Al reactive material. At a moderate strain rate, the reaction delay of PTFE/Al increased, and the reaction duration and degree decreased, with the increase of aluminum particle size. Under the strong impact of explosive loading, aluminum particle size has little effect on the reaction delay, which maintains at about 1.5 μs–2.5 μs, but the reaction durability and degree of reaction of PTFE/Al decrease with increasing aluminum particle size. There is also a strain rate threshold for the shock-induced reaction of PTFE/Al reactive material, which is closely related to aluminum particle size. The shock-induced reaction occurs when the strain rate threshold is exceeded.

为了获得采用不同铝(Al)粒径制备而成的聚四氟乙烯/铝(PTFE/Al)活性药型罩作用双层间隔靶的毁伤威力特性,采用模压烧结成型法制备了5种不同Al粒径(10,30,70,200μm,50/70μm)的PTFE/Al活性药型罩,并开展了相应的静爆威力实验.研究结果表明:随着Al粒径从10μm增加到200μm时,活性射流对钢靶和铝靶的破孔面积、等效破裂孔直径、破孔隆起高度以及形成的破坏区域体积均呈现减小趋势,当Al粒径为10μm时破坏钢靶的毁伤参量为SSteel=0.4 CD(装药直径)、hAl=0.48 CD、VSteel=420 cm3,破坏铝靶的毁伤参量为SAl=3.8 CD、hAl=1.72 CD、VAl=2280 cm3.采用50 nm/70μm级配Al粒径的PTFE/Al活性射流对钢靶的穿孔效果显著提高,等效破裂孔直径dSteel=0.59 CD.结合实验相关数据拟合得到了活性射流对后效铝靶的爆裂毁伤效应分析模型.

为研究孔隙度对富铝含量聚四氟乙烯/铝(PTFE/Al)含能材料冲击温升效应的影响,采用考虑熔化效应的一维粘塑性孔洞塌缩模型,对该材料的冲击温升进行了理论分析.建立孔隙度分别为10％、20％、30％的富铝PTFE/Al细观离散化模型,并借助非线性动力有限元软件AUTO-DYN开展细观数值模拟,对冲击加载下含孔隙富铝PTFE/Al含能材料的孔洞压缩及温升规律进行了分析.通过分离式霍普金森压杆实验对数值模拟结果进行了验证.结果表明:材料内部温度随着入射杆的周期性加载总体呈现出间歇性升高的现象;在压缩过程中,材料内部温度升高主要受孔洞内径速度和屈服强度的影响,且孔隙度为10％的富铝PTFE/Al含能材料(质量配比50/50,试件尺寸φ8 mm×5 mm)相比孔隙度为20％和30％的富铝含量PTFE/Al含能材料,其温度升高最高.研究结果可为PTFE/Al含能材料的工程化应用提供参考.

The asymmetric nitro-Mannich reactions of nitroalkanes and in situ generated N-Boc-imines were achieved with a new type of thiourea-guanidine bifunctional organocatalyst. The novel transformations exhibited good diastereoselectivities, and the adducts bearing adjacent chiral centers were generally obtained in moderate to high enantioselectivities (up to 94% ee). This reaction provides a concise and alternative route converting readily accessible and stable N-carbamate amido sulfones into optically active 1,2-diamino compounds.