铝粒径及成型压强对Al/PTFE冲击反应的影响

Aluminum-polytetrafluoroethylene (Al/PTFE) specimens with different aluminum particle sizes of 10, 30 and 200 \begin{document}${\text{μ}}{\rm{m}}$\end{document} and different molding pressures were prepared by compression molding and sintering. The impact-initiation test was carried out with split Hopkinson pressure bar (SHPB), and the reaction of the reactive materials was recorded by a high-speed photography device. It shows that with the increase of molding pressure, the speed threshold of impact-initiation of the specimen increases and then decreases. When the particle sizes of aluminum powder is around 10 \begin{document}${\text{μ}}{\rm{m}}$\end{document} or 30 \begin{document}${\text{μ}}{\rm{m}}$\end{document}, specimens with higher molding pressure can react with ignition delay time of 1000-1100 \begin{document}${\text{μ}}{\rm{s}}$\end{document}, causing a sudden drawdown of the speed threshold of impact-initiation; for the specimens with 200 \begin{document}${\text{μ}}{\rm{m}}$\end{document} aluminum powder, the ignition delay time stays around 600 \begin{document}${\text{μ}}{\rm{s}}$\end{document}. The speed threshold of impact-initiation raises as the particle size of aluminum increases, under the same molding pressure. The impact ignition of the reactive material is related to the microscopic defects, the propagation of the stress wave in the SHPB device, the amplitude of the stress pulse and the destruction process of the material.