Combustion of Energetic Porous Silicon Composites Containing Different Oxidizers

We present a quantitative investigation of combustion of on-chip porous silicon (PS) energetic materials using oxidizers with improved moisture stability and/or minimized environmental impact compared to sodium perchlorate (NaClO₄). Material properties of the PS films were characterized using gas adsorption porosimetry and profilometry to determine specific surface area, porosity, and etch depth. PS energetic composites were formed using melt-penetrated or solution-deposited oxidizers into the pores. Combustion was characterized by high speed imaging and bomb calorimetry. The flame speeds quantified for PS/sulfur and PS/nitrate systems varied in the ranges of 2.9-3.7 m s^-1and 3.1-21 m s^-1, respectively. The experimental combustion enthalpies are reported for different oxidizer systems in both inert and oxidizing environments. For the PS/sulfur and the PS/nitrate systems, the experimental heats of combustion were comparable to those calculated for the thermodynamic equilibrium and taking into account an increased reactivity of PS due to the hydrogen terminated silicon surface.