Investigation of localized reaction initiation in polytetrafluoroethylene/aluminum reactive materials under shock compression

The localized initiation and reaction extent in polytetrafluoroethylene/aluminum (PTFE/Al) reactive materials under shock compression were investigated through experimental, numerical, and theoretical analyses. Quasi-sealed chamber experiments were conducted to obtain energy release efficiency for various reactive materials, including tungsten (W)-enhanced, low-density, mass-reduced, and pristine PTFE/Al composites. Non-reactive mesoscale numerical models were established based on computed tomography slices to simulate shock compression and obtain thermal responses. Vented chamber calorimetry models and reaction kinetics were employed to analyze the factors affecting energy release. The results show that dense PTFE/Al/W and low-density PTFE/Al have enhanced energy release efficiency compared to pristine dense PTFE/Al, while mass-reduced counterparts exhibit comparable energy release efficiency. Tungsten particles and porous structures effectively increase particle deformation and local temperature while enhancing reactive component mixing in composites. Reaction initiation is more likely controlled by the local temperature in composites rather than the overall shock temperature. The energy deposition rate inside the chamber exceeds the energy loss from ventilation, with quasi-static pressure peaks determined by participated reactive material mass. The degree of reaction completion primarily depends on the initial partial ignition scale induced by shock compression in reactive materials.