Porous Si/Al-Si spherical powders with controllable structure and superior reactivity via dealloying of Al-Si

Energetic porous fuels are attractive for their high reactivity. In this study, porous silicon/aluminum–silicon (pSi/AlSi@pSi) powders were prepared via dealloying Al-Si alloy. Results demonstrate that pSi and AlSi@pSi with evenly distributed pores and tailorable porosity were obtained. AlSi@pSi shows a core–shell structure with Al-Si alloy core and porous Si shell. Thermal properties indicate that consistent with its core–shell structure, the oxidation of AlSi@pSi can be considered as a combination of pSi and Al-Si alloy. The main oxidation is kicked in by the reaction of the Al-Si alloy core, followed by the intense reaction of the porous Si shell. The combustion characterization demonstrates that the dramatically improved reactivity of porous samples is attributed to the ultra-high kinetics of porous Si outperforming nano-sized aluminum (n-Al). The shorter ignition delay and combustion duration of porous samples than Al-Si alloy and n-Al result from the lower apparent activation energy (E0) and the low initiation oxidation temperature for porous Si. The different oxidation processes for AlSi@pSi under thermal oxidation and combustion owe to the high oxidation peak temperature and low E0 of porous Si. Above all, the prepared porous fuels with tailorable porosity and superior reactivity than n-Al are promising fuels in energetic materials.