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.