炸药纳米晶界面组装机制及冲击起爆性能研究

Nano explosives exhibit a lot of outstanding performances such as the high energy releasing velocity and high sensitivity to short-pulse stimulation, which attained practical applications as the initiating explosives in modern weapon systems. However, nano explosives are easily to agglomerate and lose some performance underthe stimulation from exoteric environment such as the heat, solvent, electron beam, etc. For a long time, such disordered thermal agglomeration phenomenon was an urgent problem needing to be overcome. Currently, the basic theory on influences of agglomeration is not clear, and few works were done from another view for the ordered particle interfacial assembly based on the environment abduction. In this program, nano CL-20 and other explosives are selected to point out the interfacial assembly and structure evolution behaviors with the combination of experimental observations and theoretical simulation. Then, a particle assembly mechanism will be proposed based on the kinetic model for crystal growth resulting large and uniform crystals, and the shock initiation performance of crystals after such assembly will also be investigated. From this research we can obtain the key driving force of explosive nano-crystallines interfacial assembly from surface physical and chemical properties, facilitating the understanding of agglomeration and crystal growth process. In addition, results achieved from this research can be favorable to study explosive crystals with different morphology, providing a novel route for the preparation of high-quality explosive crystals with high energy and low sensitivity, which can definitely improve the safety performance of munitions.

纳米炸药具有能量释放速率高、对短脉冲刺激敏感等优异性能，在武器用起爆传爆序列已获实际应用，但其在制备、表征和应用过程中均易受外界环境如热、溶剂、电子束等刺激发生颗粒团聚而失去部分性能。长期以来，无序热团聚一直是该领域所需迫切解决的重要问题，当前影响纳米炸药团聚的基础理论尚不清晰，且缺少从另一角度对特定环境诱导的纳米颗粒有序界面组装进行研究。本项目以CL-20等纳米炸药为对象，结合实验观测与理论模拟，研究炸药纳米晶在溶剂、热诱导下的颗粒组装和结构演化行为，分析其定向生成均匀大颗粒晶体的反应机制，建立纳米晶组装动力学模型，并研究组装晶体的冲击起爆性能。本研究不仅可以从表界面物理化学探明炸药纳米晶界面组装的关键驱动力，对揭示其团聚及晶体学生长过程有重要意义；还可为不同晶体形态炸药的研制起到指导作用，有望为高品质炸药晶体制备提供一条新的技术途径，降低敏感高能炸药的冲击波感度，显著改善弹药安全性能。

纳米炸药具有临界起爆直径低、能量释放速率快等优点，在武器用始发药等领域有重要应用价值。然而，纳米炸药在受到外部刺激条件下容易发生颗粒团聚。长期以来，无序热团聚一直是该领域所需迫切解决的重要问题，而缺少从另一角度对特定环境诱导的纳米颗粒有序界面组装进行研究。在本项目中，我们首次发现并报道了纳米炸药在溶剂、热的双重诱导下，会发生有序界面组装的行为。炸药原材料颗粒状态、溶剂介质的种类、反应温度、以及表面活性剂等功能添加剂都会对组装晶体产生明显影响。同时，该自组装过程在含能材料中具有一定普适性，我们选取典型的“高能派”代表CL-20、HMX以及“钝感派”代表TATB、LLM-105这四种炸药，深入开展了组装行为和规律研究。所获得的组装炸药粒径可从几微米至几百微米、形貌和粒径十分均匀、表面光滑、内部无杂质缺陷，且晶体强度、密度均与通过溶剂/反溶剂重结晶获得的高品质炸药相当。通过对组装过程的中间态进行捕捉，结合晶体内切剖面表征和晶型定量分析，我们成功获得了纳米炸药发生热介稳组装的反应机制，并建立了Avrami组装动力学模型。与此同时，采用DFT、分子动力学和粗粒方法，对CL-20纳米晶在不同溶剂中的组装行为进行了理论模拟研究。令人欣喜的是，通过自组装获得的高品质炸药机械感度显著降低，且相比于重结晶法获得的高品质炸药而言感度还要进一步降低。此外，该法相比于重结晶而言，不仅有望制备出粒径更大、分布更均一的高品质炸药晶体，同时反应过程简单，工艺放大稳定性良好。通过组装前后的炸药冲击起爆性能研究结果表明，通过炸药纳米晶界面热介稳组装的炸药晶体（如CL-20、HMX等），其晶体内部致密，不容易被冲击波引爆，冲击波感度相比于采用溶剂/非溶剂重结晶的高品质炸药晶体而言还要进一步降低，表明组装晶体的安全性能比重结晶法获得的炸药更优。也就是说，通过本项目，获得了一种十分具有应用潜力、普适性强的含能晶体构筑新策略。