Study on the reaction kinetics of metal hydroxide as an interphase for enhancing anodizing combustion on electrically controlled solid propellants

Abstract

In the presence of high voltage external power supply and electrode, an electrically controlled solid propellant (ECSP) composed of hydroxylamine nitrate (HAN) and polyvinyl alcohol (PVA) gelling agent has the characteristics of an electrically controlled reaction. The in situ solid propellant interphase (SPI) at the anode has high interface impedance, resulting in the low current density of the ECSP. In this paper, the reaction kinetics of an artificial SPI (Fe(OH)₃) at the anode are studied for evaluating ignition delay and the burning rate. The neutralization reaction of metal hydroxides and the electrolysis of water reduce ignition delay. The decomposition of metal hydroxides increases the burning rate. Metal hydroxides serve as interfaces, resulting in a decrease in interface impedance and an increase in the current density of the SPI/propellant. The increase in current density indicates that the electrolysis rate of HAN is accelerated, and the input power is increased without affecting the performance of multiple start-stop operations. The study of gas production (such as CO and CO₂) over time confirms that metal hydroxide can promote the oxidation and combustion of the propellant. The ECSP with SPI-Cu₂(OH)₃(NO₃) shows improved ignition delay and burning rate. The ECSP with SPI-Fe(OH)₃ shows the best performance, resulting in an 80% reduction in ignition delay and a 116% increase in the burning rate. This research focuses on the reaction mechanism of interfacial chemistry and highlights the importance of interfacial design for performance.