Al/PTFE活性材料的动态力学行为和撞击点火特性

In order to investigate the dynamic behavior and ignition mechanism of Al/polytetrafluoroethylene(PTFE) reactive material under dynamic loading, a Split Hopkinson Pressure Bar (SHPB) was used to conduct the dynamic compression experiment on reactive materials with different molding pressure. Experimental results show that the Al/PTFE reactive material exhibits typical elastic-plastic mechanical behavior under dynamic loading at strain rate ranging from 2960 s^-1 to 5150 s^-1. The yield strength and hardening modulus of Al/PTFE reactive materials do not show strain rate effect when the molding pressure is 50-150 MPa. The velocity ignition threshold increases slowly from 28.77 m•s^-1 to 29.22 m•s^-1 with the molding pressure. When the molding pressure increases to 100 MPa, the velocity ignition threshold drops significantly to 26.60 m•s^-1. With the increase of the impact velocity, the ignition delay time for reactive materials with the molding pressure of 100-150 MPa decreases from 1000-1100 μs to 600-700 μs, while that of reactive materials with the molding pressure of 30-80 MPa maintains at 600-700 μs. Combining with results of Scanning Electron Microscopy, it is found that the local larger pores inside the reactive materials with higher molding pressure is the main factor for the sudden drop of the velocity ignition threshold. Therefore, the impact ignition characteristics of Al/PTFE reactive materials are mainly related to the external loading form and the internal micro-morphology.