Comparison of the Ignition Behavior of Nitrates and Perchlorates for Electrically Controlled Propellants

ABSTRACT While electrically controlled propellants (ECSPs) using lithium perchlorate or hydroxylammonium nitrate as the oxidizer have received the most attention, relatively little attention has been paid to other salts. This study provides a direct comparison of the ignition behavior of pseudo‐propellants that use nitrate and perchlorate anions with alkali metal (Li + , K + , Na + ) and ammonium cations. Eight total propellants were formulated with paraffin wax as a binder and multi‐walled carbon nanotubes as a conductive additive to facilitate initial heating. Thermal analyses were conducted for each salt and its corresponding propellant. All propellants achieved ignition with only an electrical stimulus except for the propellant based on ammonium perchlorate. The ignition delay of the remaining seven propellants was characterized by a range of voltages. Using a combination of high‐speed imaging, high‐speed IR imaging, and analysis of current draw, details of the ignition behavior have been extracted. The order of ignition delay tended to favor the smaller cations, which promote electrochemistry and enable faster ignition. The Na + and K + nitrates ignited faster than their perchlorate counterparts, while the Li + perchlorate ignited faster than the nitrate. Overall, the Na + nitrate ignited the fastest, which was attributed to enhanced electrochemistry in comparison to the perchlorates. The results of the study suggest that for situations where responsiveness is most important, non‐traditional ECSP oxidizers may offer benefits.