Shock initiation of reactive nanolaminates

Abstract

The production of heat by reactive nanomaterials occurs at a fuel/oxidizer interface. In order to understand how such materials can be initiated by shock, we studied a model system consisting of a reactive nanolaminate (RNL) with a well-defined planar interface. In addition, an organic thin layer could be intercalated between the fuel and oxidizer to modulate the reaction. We studied a stoichiometric mixture of Zr fuel and CuO oxidizer and the modulator layer was polyurea produced by molecular layer deposition. The RNL was shocked using 0.5 mm diameter Al flyer plates launched by a pulsed laser at 1.5 km/s. We found that little or no reaction was produced immediately under the flyer plate where the interface experiences compression only. Instead the reaction was efficiently initiated by shear waves propagating out from the edges of the flyer plate. The RNL reaction temperature during shock was 4000K, and after the shock dissipated, the RNL reacted at 3000K. Modulator layers caused the reaction to slow down with the effect increasing with increasing modulator thickness up to 500 nm.