基于多孔硅纳米线的含能材料的制备及性能调控

Preparation and Performance Regulation of Energetic Materials Based on Porous Silicon Nanowires

纳米多孔硅由于其海绵状的孔隙结构,氧化剂很难充分填充,导致多孔硅复合含能材料多为富燃料体系;同时其孔隙率难以调节,无法精确控制氧燃比。针对以上问题,以紧密排列的单层聚苯乙烯微球为模板,通过反应性离子刻蚀(Reaction Ion Etching,RIE)技术结合金属辅助化学刻蚀(Metal-Assisted Chemical Etching,MACE)制备得到了形貌结构可控的多孔硅纳米线,通过控制RIE时间能够精准调节多孔硅复合体系的氧燃比,同时二维线状结构非常有利于氧化剂的高效填充。结果表明,在RIE时间为80s,即硅纳米线直径为150nm左右时,复合含能体系达到最佳化学计量反应平衡,能量输出最佳。同时,选用不同电阻率的硅片制备得到不同结构形貌的硅纳米线,电阻率越低,纳米复合含能体系中的硅纳米线结构越疏松多孔,不仅能够有效缩短传质传热距离,降低反应活化能,有利于增强反应放热;而且能提升燃烧性能,有利于点火,为硅基含能材料的发展提供了新的思路。

Due to the sponge-like pore structure of nanoporous silicon,it is difficult to fill with oxidants.This is the reason why the porous silicon composite energetic materials are mostly in a fuel-rich state.Meanwhile,adjusting the porosity of nanoporous silicon efficiently remains a challenge,so the oxygen-fuel ratio cannot be precisely controlled.In order to solve these above problems,the closely-arranged monolayer polystyrene microspheres were used as the template,and the nanoporous silicon nanowires with controllable morphologies and structures are obtained through reactive ion etching(RIE)technology and metal-assisted chemical etching(MACE).Porous silicon nanowires can precisely adjust the oxygen-fuel ratio of the composite systems by controlling the RIE time.At the same time,the two-dimensional linear structure is very beneficial to promote the filling ratio efficiently.The results show that the composite energetic system achieves the best stoichiometric reaction equilibrium and the energy output when the RIE time is 80s(the diameter of silicon nanowire of about 150nm).Moreover,the silicon nanowires with different structures and morphologies were prepared by using silicon wafers with different resistivity.The structure of silicon nanowires prepared by silicon wafers with lower resistivity is looser and more porous.The silicon nanowires prepared by silicon wafers with low resistivity can not only effectively shorten the heat transfer distance and reduce the activation energy of the reaction but also enhance the heat release of the reaction.It is beneficial to improve the combustion performance and facilitate the ignition of the nanocomposite energetic systems.The work could provide a new idea for the development of silicon-based energetic materials.