Nitrogen-Rich Salts as Energetic Additives for Hypergolic Ionic Liquids with Hydrogen Peroxide

Abstract

For the substitution of toxic and environmentally harmful hypergolic bipropellants, the combination of ionic liquids and highly concentrated hydrogen peroxide is investigated. In this work, guanidinium thiocyanate [Gua][SCN] and choline thiocyanate [Ch][SCN] were tested as energetic additives for hypergolic ionic liquids. Viscosities and densities of the new fuels were measured, heat of formation was determined and specific impulse was calculated. Ignition behavior of the propellants was evaluated via drop-on-pool tests. The ignition delay time – the time span between first contact of oxidizer and fuel and first formation of a flame – of the different hypergolic propellant combinations was compared and the influence of the additives on the ignition capability was investigated. Overall, it was found that [Gua][SCN] was able to reduce the ignition delay compared to the base fluid [Emim][SCN] but did decrease the specific impulse. In case of the additive [Ch][SCN], the reverse was found: here, both a gentle increase in the specific impulse and the volumetric specific impulse could be achieved.