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oai:drum.lib.umd.edu:1903/219442019-06-20T02:36:40Zcom_1903_2263com_1903_1654com_1903_2col_1903_2795col_1903_3

Bergbreiter, Sarah Churaman, Wayne Anthony Digital Repository at the University of Maryland University of Maryland (College Park, Md.) Mechanical Engineering 2019-06-19T05:41:03Z 2019-06-19T05:41:03Z 2019 https://doi.org/10.13016/erzv-shp0 http://hdl.handle.net/1903/21944 Energetic porous silicon has emerged as a novel on-chip energetic material capable of generating thrust that can be harnessed for positioning of millimeter and micron-scale mobile platforms such as microrobots and nano-satellites. Porous silicon becomes reactive when nano-scale pores are infused with an oxidizer such as sodium perchlorate. In this work, energetic porous silicon was investigated as a means of propulsion by quantifying thrust and impulse produced during the exothermic reaction as a function of porosity. The baseline porous silicon devices were two millimeter diameter and etched to a target depth of 25 microns. As a result of changing porosity, a 7x increase in thrust performance and a 16x increase in impulse performance was demonstrated. The highest thrust and impulse values measured were 680 mN and 266 micron Newton seconds respectively from a 2 mm diameter porous silicon device with 72 % porosity. Limitations and trade-offs associated with arrays of devices were presented by studying the effects of scaling porous silicon area, and characterizing thrust when arrays of porous silicon micro-thruster devices were ignited simultaneously. In addition, the effects of sympathetic ignition were evaluated to better understand how closely independent devices could be physically spaced on a 1 cm2 chip. 3D nozzles were fabricated to study confinement effects by varying nozzle throat diameter, and divergent angle. It was shown that integration of a nozzle (throat diameter of 0.75 mm and a divergent angle of theta = 10 degrees) resulted in approximately 4X increase in thrust, and 4X increase in impulse. This study highlighted enhancements to thrust and impulse generated by porous silicon, identified trade-offs associated with simultaneous activation of multiple devices on a 1 cm2 chip, and showed energetic porous silicon as a viable solid propellant for propulsion of nano-satellites and micro-robots. en Investigating Energetic Porous Silicon as a Solid Propellant Micro-Thruster Dissertation Mechanical engineering energetic micro-thruster porous silicon open.access