Borohydride Ionic Liquids and Borane/Ionic‐Liquid Solutions as Hypergolic Fuels with Superior Low Ignition‐Delay Times

Abstract

In propellant systems, fuels of choice continue to be hydrazine and its derivatives, even though they comprise a class of acutely carcinogenic and toxic substances which exhibit rather high vapor pressures and require expensive handling procedures and costly safety precautions. Hypergolic ionic liquids tend to have low volatility and high thermal and chemical stability, and often exhibit wide liquid ranges, which could allow the use of these substances as bipropellant fuels under a variety of conditions. A new family of borohydride ionic liquids and borane-ionic-liquid solutions is described which meets nearly all of the desired important criteria for well-performing fuels. They exhibit ignition-delay times that are superior to that of any known hypergolic ionic liquid and may thus be legitimate replacements for hydrazine and its derivatives.