Solid Propellant Burn Rate Modifiers Based on Reactive Nanocomposite Materials

摘要

Burn rate modifiers for solid propellants are being developed based on reactive materials prepared by Arrested Reactive Milling. The materials include nanocomposite thermite compositions using aluminum as a fuel and oxides of iron, molybdenum and copper as oxidizers. The materials are characterized using a set of laboratory tests. Conditions for preparation of viable propellant additives are selected based on the reduced ignition temperature and accelerated burn rate achieved for the prepared nanocomposite powders. The compositions addressed in this study are metal rich, minimizing the energetic penalty due to adding these materials to the propellant formulations. Propellants are formulated with selected samples and their mechanical and burn properties are assessed. Processing reactive nanocomposite powders with conventional propellant formulations was successful and mechanical properties were acceptable. Strand combustion experiments and subscale ballistic evaluations showed substantial increase in the burn rate over a broad range of pressures achieved with replacement of only 5 % of aluminum in aluminized propellant with new materials. Furthermore, the slope break in the log of burn rate vs. log of pressure curve is shifted to a higher pressure for the formulation with the nanocomposite modifier. This shift is expected to be advantageous for the design of rocket motors operating at pressures higher than those used for the current high performance aluminized HTPB propellants.