Synthesis Of Porous Silicon/ Sulfur Composite Material And Its Explosive Performance Evaluation

Energetic material is a kind of material that can generate violent oxidation-reduction reactions by itself and releases lots of energy under the outside energy stimulus. The application of traditional energetic materials has been gradually limited for low explosion energy and environmental contamination and other shortages. And thus, developing higher explosion energy and more environmental friendly energetic materials is very promising and meaningful. Porous silicon energetic materials have attracted extensive attention for their higher explosive energy properties and lower environmental pollution. However, study work carried out on its explosion performance and explosion mechanism is still inadequate. Porous silicon was prepared by electrochemical anodic oxidation technique taking n-type silicon wafer as raw material, then porous silicon/S composite material was synthesized using sulfur as oxidant. The effects of current densities, contents of sulfur and other influencing factors on the explosive performance of the composite energetic material were investigated. Main conclusions are as follows:(1) N-type silicon wafer with electrical resistivity of 6.6520⁸.3260Ω·cm was taken to prepare porous silicon by constant current electrochemical anodic oxidation technique. The effects of current densities, oxidation time, electrolyte composition, temperature and intensity of illumination on the porous silicon porosity were studied.(2) The structure, physical and chemical properties of porous silicon prepared under different current densities were characterized by SEM and FT-IR. Results showed that cracks on the porous silicon surface were few and wide when prepared by constant current. While by pulse current many fine cracks appeared, and a double-layer structure in the cross-section was observed. The thickness of porous layers was 85μm or so, and the silicon columns was about 2³Î¼m wide. There were lots of Si-Hx bonds on the porous silicon surface.(3) Influence of different current signals on the explosion performance of the porous silicon composite materials was investigated. The optimal porous silicon preparation conditions were obtained via optimization experiment: constant current anodic oxidation current density 40mA·cm^-2, oxidating time 20min, HF: C₂H₅OH =3:1(v/v); while for the pulse current anodic oxidation, i_max=40 mA·cm^-2 , i_min=4 mA·cm^-2, 20³0 cycle numbers, oxidating time 20min, HF:C₂H₅OH =3:1(v/v).(4) Porous silicon/S materials were prepared using sublimed sulfur and regenerate sulfur as oxidant respectively. Influence of sulfur concentrations, storage methods, porous layer porosities and other influencing factors on the explosive performance of the composite materials were investigated individually. Color temperature of the porous silicon/S composite material was measured as 3431K.(5) FT-IR and XPS methods were taken to characterize the surface bonds of the porous silicon/S and porous silicon/Gd(NO3)3 composite materials respectively, results proved that there were interactions between oxidants and porous silicon, some bonds related to S detected in the materials'structures, and Si-Hx bonds on the surface were oxidized to Si-O bonds.