Safe, High-Specific-Impulse Composite Propellant with Minimized Slag and Emissions

USAF desires solid propellants with performance and safety equal or better than existing ammonium perchlorate composite propellants but with reduced aluminum slag and HCl formation. Helicon will demonstrate propellants in which the aluminum powder is replaced by in situ grown aluminum nanocomposite materials, eliminating Al slag formation. Using a novel, scalable in situ nanoparticle growth process, Helicon produces high-energy reactive composites with near-molecular-level intermixing of the aluminum fuel and polymer binder. The resulting composites consist of extremely small, oxide-free aluminum nanoparticles (nAl) individually bonded to molecules of polymer binders. Helicon’s technology has several advantages over competing approaches. In situ nAl materials are safe to handle, insensitive, compatible with energetic ingredients, and impervious to moisture. Importantly, this technology increases propellant density specific impulse. Due to high combustion efficiency and lack of agglomeration, higher aluminum mass loadings are possible, surpassing conventional limits of around 20%. Two-phase flow losses are reduced. Temperature sensitivity is also reduced, allowing increased performance at lower temperatures than conventional AP-based propellants. To address HCl emissions, Helicon will evaluate additives such as sodium nitrate. Propellant formulation efforts will be guided by thermochemical calculations, such that the Phase I formulations will have higher predicted density specific impulse than the baseline. Helicon's nanocomposite materials provide the increased performance required to meet goals of the REACH initiative without negative impacts to safety, and using current energetic materials processing technology.