Shock-induced chemical reaction characteristics of PTFE-Al-Bi₂O₃ reactive materials

A ternary system of PTFE/Al/Bi₂O₃ is constructed by incorporating PTFE-based reactive material and thermite for enhancing the energy release of the PTFE-based reactive material. The effects of Bi₂O₃ in the PTFE/Al/Bi₂O₃ on both mechanical properties and the energy release were investigated through various tests such as thermogravimetry-differential scanning calorimetry, adiabatic oxygen bomb test and split Hopkinson pressure bar test. The microstructure observed through scanning electron microscope and X-ray diffraction results are used to analyze the ignition and reaction mechanism of PTFE/Al/Bi₂O₃. The results indicate that the PTFE/Al/Bi₂O₃ are capable of triggering the exothermic reaction of molten PTFE/Bi₂O₃ and Al/Bi₂O₃ over the PTFE/Al reactive materials, thereby promoting reactions. The excessive aluminum in the ternary system is beneficial for increasing energy release. The ignition of shock-induced chemical reactions in PTFE/Al/Bi₂O₃ is closely related to the material fracture. The dominant mechanism for hot-spot generation under Split Hopkinson Pressure Bar test is the frictional temperature rise at the microcrack after failure.