Experimental studies on effects of electrode material and voltage on electrolytic decomposition of Hydroxylammonium nitrate solution

Abstract

Hydroxylammonium nitrate (HAN)-based propellants have been attracting attention as future low-toxicity liquid propellants owing to their ionic properties. HAN-based propellants are primarily decomposed via catalytic reactions. However, this method has several drawbacks, such as catalyst preheating and deactivation. Therefore, in this study, the electrical characteristics of the electrolysis process of a HAN solution, as well as the by-product gases and reaction residues were analyzed considering the electrode material and applied voltage as the controlling variables. SUS (a designation of stainless steel) electrodes have higher durability than Cu electrodes; however, their decomposition proceeds more slowly because of the suppression of the initial reaction at low voltages. This study confirmed that this suppression could be significantly addressed at a high voltage of 400 V. The investigated electrolytic decomposition mechanism of the HAN solution was validated by analyzing the gases generated during the electrolysis and residue after the reaction, using Fourier-transform infrared spectroscopy. This study has important implications for the development of volume-limited propulsion systems, such as micro-thrusters.