撞击加载下炸药晶体的破碎特征

Fracture Feature of Explosive Crystal under Impact Loading

分别对AP、HMX、RDX晶体进行落锤撞击加载,用环境扫描电镜观察了3种晶体的破碎特点。实验结果显示:3种晶体虽然都出现剪切带,但在破碎特征方面有明显不同,其中AP以晶体的局部脆性断裂为主,晶体的破碎程度最小,且加载后仍呈颗粒状;HMX和RDX以晶体的塑性变形和破碎为主,且加载后多呈现"薄片"结构;加载后RDX晶体比HMX易分散,但HMX晶体的破碎程度更严重。研究认为:晶体的撞击加载是力-热转化过程,晶体内部热点形成与晶体的力学强度有关,认为这一转换过程与晶体的分子组成和热反应机理有关。在低速撞击加载下,具有较强分子稳定性的AP晶体破碎程度最小,且不易形成热点。对于RDX和HMX晶体,"薄片"结构的形成原因除晶体破碎外,内部还可能存在相变、转晶等变化。

The response of three granules（AP,HMX and RDX） to drop-weight impact loading has been studied respectively using ESEM.The results showed that they all had the shear bands,but the local brittle rupture occurred in the majority of AP and it had least grain fragmentation,the plastic deformation and fragmentation occured in the HMX and RDX,and the flake both appeared in them and HMX had more flakes.The dispersion of RDX was more easily than HMX,but the fracture of HMX was much more severely.The research suggested that the impact of particles was the flexibility release process（ie.the particles force-thermal conversion process）,the formation of hot spot was related to the mechanics property of particles.The particle macroscopic response was relevant to the formation of particles and thermal reaction mechanism.In the low velocity of impact loading,the particle of AP,with the strong stability of molecule,had the least fragmentation and was difficult to from the hot spot.With regard to the particles of RDX and HMX,the reason to the fromation of flake was not just the fracture of particle,but the phase transition and crystal transformation exsited.