Sponge-like Al/PVDF films with laser sensitivity and high combustion performance prepared by rapid phase inversion

Abstract The aluminum-fluorine reaction hold great potential in crippling Al pre-combustion sintering and agglomeration during combustion. Herein, the laser-sensitive Al/PVDF fuel rich films were prepared by employing a sponge-like microvoids structure through phase inversion coupling with micro-segmented flow, displaying the laser power threshold and ignition delay time by less than 4.8 J·cm-2 and 1.57 ms compared to unignited dense Al/PVDF pellet by a 19.6 J·cm-2 laser. The decreased Al atoms plasma electron temperature and a reduced F irons density with the increased Al content, implies a reduction of Al-F reaction ratio. This Al/PVDF films reveal 5 times higher flame propagation rate and mass consumption compared to the vacuum freeze-dried one, contributing to enhanced convective heat transfer in sponge-like microvoids channels. The ambient oxygen and released HF diffusion in microvoids, creating Al-F, Al-O competitive reaction path. The Al-O and Al-F reactions proportions of Al-30, Al-50 and Al-70 were determined by 2: 98, 41:59 and 74.5: 22 after inferring HF and evaporated AlF3 combustion products by several assumption and calculation based on XPS results. The released gaseous H2 and AlF3 from Al droplet surface reduce nano-aluminum sintering. The different reaction paths of Al/PVDF films during combustion and thermal analysis were analyzed.