Enhanced thermal-and impact-initiated reactions of PTFE/Al energetic materials through ultrasonic-assisted core-shell construction

A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al(CS-PA)energetic materials through ultrasonic-assisted mixing.The low-cost micrometer-sized PTFE and Al particles were used as starting materials.Under high-power ultrasonic waves,the PTFE powder was dispersed into nano-to sub-micrometer-sized particles and then encap-sulated the Al microparticles to form the core-shell structure.The heat of combustion,burning rate,and pressurization rate of the powdered CS-PA were measured.The thermal-initiated reaction behavior was further evaluated using thermogravimetry-differential scanning calorimetry.Subsequently,the bulk CS-PA with a uniform microstructure was obtained via cold isostatic pressing of the powdered CS-PA fol-lowed by vacuum sintering.For the bulk CS-PA,the quasi-static compression behavior was characterized,and the impact-initiated reaction processes were conducted using the Split Hopkinson Pressure Bar(SHPB)and evaluated by a high-speed camera.Compared to physically mixed PTFE/Al materials,the powdered and bulk CS-PA demonstrated enhanced thermal-and impact-initiated reaction characteristics respectively,proving the effectiveness of our approach for constructing core-shell structures.