Replacing the Al₂O₃ Shell on Al Particles with an Oxidizing Salt, Aluminum Iodate Hexahydrate. Part I: Reactivity

Improvements in the reactivity, measured in terms of flame speed, for aluminum-based energetic mixtures are increased by a factor of 2-3 by replacing the Al₂O₃ passivation layer of aluminum (Al) nanoparticles with aluminum iodate hexahydrate (AIH), an oxidizing salt. The Al-AIH nanoparticles are examined under transmission electron microscopy. An AIH passivation shell surrounding the Al core particle is a more reactive composite structure than Al₂O₃ passivation around Al which facilitates increased reaction rates with flame speeds as high as 3200 m/s. Flame speed measurements are used to show that reaction rates in AIH mixtures are determined by the AIH/Al₂O₃ ratio, oxygen balance, and β-HIO₃. Further optimization of these properties will ultimately boost significant increases in the reaction rates of the energetic materials presented in this article.