IGNITION CHARACTERISTICS OF NANOTHERMITE SYSTEMS

Nanothermites are a class of materials that have been of much interest over the past ten years. Variations in methods of synthesis and processing have allowed these materials to be tailored to many different applications (e.g., percussion primers, electric matches, low energy ignition devices, etc.). These applications require wide ranges of reactive energy outputs, reaction rates, and ignition sensitivities. Appropriate characterization methods have been developed for mechanical impact, thermal, and electrostatic discharge sensitivities. This study presents an explanation of ignition delay times of an Al-Fe2O3 nanoenergetic mixture during exposure to a laser pulse as a function of a sample density. It was shown that the porosity of the energetic material significantly affects the ignition delay time due to the dependence on thermal properties as the function of that parameter. The effect of porosity on ignition delay was also investigated using a mathematical model. The model verified that an increase in porosity significantly decreases ignition delay time due to a much lower thermal conductivity and heat capacity of the sample. Electrostatic discharge sensitivity of the nanoenergetic materials was also investigated. This study determined that individual particle size and its morphology (both fuel and oxidizer), specific heat capacity of the nanothermite mixture, degree of consolidation, and processing methods can all have a significant effect on the sensitivity of the nanoenergetic materials to ignition by electrostatic discharge (ESD).