Combustion of Energetic Porous Silicon Composites Containing Different Oxidizers

We present a quantitative investigation of com- bustion of on-chip porous silicon (PS) energetic materials using oxidizers with improved moisture stability and/or minimized environmental impact compared to sodium per- chlorate (NaClO4). Material properties of the PS films were characterized using gas adsorption porosimetry and profil- ometry 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 imag- ing 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 � 1 and 3.1-21 m s � 1 , respectively. The experimen- tal combustion enthalpies are reported for different oxidiz- er 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 terminat- ed silicon surface.