Investigation On The Preparation Of Silicon Nanowires And Its Application For Energetic Materials

Silicon nanowires tightly bonded to the silicon substrate have been prepared by"two-step"method in metal-assisted chemical etching.The P-type single crystal silicon wafer is the raw material for preparing silicon nanowires.Silicon nanowire-based energetic materials are obtained by compounding sodium perchlorate with silicon nanowires by vacuum differential pressure filling or physical mixing.Then,the influence of etching time and silicon resistivity on the thermal and combustion performance of silicon nanowire-based energetic materials have been investigated.The research results are as follows:The microstructure of silicon nanowires is significantly affected by the resistivity of silicon wafers.As the resistivity decreases,the silicon nanowire becomes porous and the single crystal structure is destroyed.When the silicon wafer with a resistivity of 8¹2?·cm is used as a raw material,the length of the silicon nanowire is linearly related to the etching time,and the etching rate is about 0.36?m·min^-1.The thermal performance of silicon nanowire-based energetic materials prepared by physical mixing have been obtained by DSC.The results show that the heat of silicon nanowire-based energetic materials decreases with increasing etching time,and the heat decreases with the decrease of silicon resistivity.The silicon nanowire-based energetic materials prepared by using a silicon wafer having a resistivity of 0.001 to 0.005?·cm yields 1543J·g^-1,which is the largest heat value measured in silicon nanowire-based energetic materials.Laser ignition experiment of silicon nanowire-based energetic materials prepared by vacuum differential pressure method reveals that this energetic materials has a longer flame duration and higher brightness as the etching time increases,and with the resistivity of silicon wafer decreased,the flame brightness becomes higher.In order to solve the problem of moisture absorption of silicon nanowire-based energetic materials prepared by filling sodium perchlorate,silicon nanowire-based energetic material have been prepared by sequentially filling sodium perchlorate and sulfur on silicon nanowires in the same method.The result shows that the filling of sulfur can effectively alleviates its hygroscopicity.The laser ignition test showed that the sample filled with sodium perchlorate and sulfur is superior to the sample filled with only sodium perchlorate in terms of flame size and duration.The study of the reactivity of silicon nanowires with different resistivities indicates that silicon nanowires prepared from lower resistivity silicon wafers have a higher degree of oxidation,but the coarse,porous structure is the key to making it exhibit higher reactivity.