High Quality Hmx Crystals In The Pbx Installation Damage Research

Pressed Polymer Bonded Explosives (PBXs) which have been used in many advanced warheads have many advantages, such as having more explosives, higher mechanics modulus, better detonation property, simple production process and shorter production cycle. But pressed PBX usually have more microcosmic defects in shaping process under hot temperature and high pressure, such as damages and crackles in explosive crystal, interfacial debonding between crystal and binder, which influence mechanical property and security property of PBX obviously. The defects in PBX include two kinds of classification, one of which is holes and cracks in raw crystal, the other is new defects induced by pressing. So it is very important to study the security and reaction mechanism under pressure and heat by studying the damage evolution mechanism.It is a focus on energetic material field to improve the security of weapon system, and the insensitive explosive’s application give an important solution to this problem. Octogen (HMX), used widely in the world, is selected to research the influences between crystal property and damages’forming in PBX shaping process, explore the method to reduce the pressing damages, and discuss the factor and mechanism which influence the damage degree.Focusing on commercial HMX and insensitive HMX, the damage forming mechanism in crystal in pressing process is studied by using uniaxial compression, Acoustic Emission, microscope technology and numerical simulation. From all experimental results the following conclusions can be obtained:(1) Several microscope technology (SEM, OMS and PLM), particle size statistics technology, small-angle X-ray scattering technology, are used to characterize the damages of HMX crystal in PBX before and after being pressed; Photoelectron Spectrun technology and wicking method are used to probe the factor influencing the emerging of damages. The results indicate that insensitive HMX have similar damage degree with common HMX under40kN. The stress increases, the crystal cracking in pressed PBX increases obviously, but the increase trend reduces. The particle size of HMX increases, the coherence strength decreases and the coating degree decreases too, which result to more cracking in pressed PBX obviously. In order to reduce the damage in pressed PBX, energrtic crystalline granules with fine or mixed particle size should be chose as the main explosives. Using TATB as one part of PBX can enhance the forming property of PBX, and lubricate the interfaces between crystals, which can reduce the pressing damage of HMX.(2) Find out the mechanics behavior of HMX particles by uniaxial compression experiment. The result of Acoustic Emission indicates that energy accumulation, fragmentation and flowing, emerge circularly in the process of compression which results the uncontinuity of acoustic emission signal; the acoustic emission characteristics decrease quickly in stress-keeping stage, which shows damage in HMX particles mostly appear at stress-rising stage.(3) The detailed study of the structure of HMX under hydrostatic pressure was performed with Vienna Ab-inito Simulation Package(VASP). Compression property curve gained by this method correspond with experiment result. At the same time, the transfer of oxygen atom was found under33.74GPa, which can help to explain the detonation mechanism.