ALUMINIZED TORPEDO PROPELLANTS

Alex (nanosize aluminum) powder is being considered by several U. S. Navy groups as a propellant additive because it markedly increases combustion rate. Extrapolating equations for single particle combustion of aluminum shows the particle life of a 100 nanometer particle to be about 40 nanoseconds. Its small particle produces oxide that would minimize being accumulated on engine parts. Alex's rapid reaction with water also suggests its use for aluminum-sea water propulsion schemes. Alex's combustion would be enhanced by its metastable structure that provides energy in the form of a heat burst that occurs at about 400 C, causing a transformation in crystal morphology. Hydroxylamine nitrate (HAN) is a monopropellant that has been considered by the Navy as an Otto Fuel II replacement. We propose a cooperative study to support NUWC-Newport by providing samples of improved Alex compatible with stabilized HAN. We would coat Alex particles with organics that would provide increased energy over oxide passivated nano-aluminum, while shielding the aluminum from premature reaction with oxidizers such as HAN during storage. Using coated particles we would determine the feasibility of producing stable HAN-based gels. We would also develop aluminized jet fuels for potential bi-propellant systems.