(470b) Production of Nano-Sized Aluminum through Cryogenic Milling

There is tremendous interest in nano-sized aluminum powder for numerous energetic applications such as liquid and solid propellant additives. The challenge however, is the selection of a scalable process that produces nano-sized aluminum powder that is stable for storage, while energetically favorable in desired uses. Thus, protection or passivation of the surface of nano-aluminum particles without substantially reducing their energy density is another significant problem. Cryogenic mechanical milling was investigated here as a novel method for the production of aluminum nanopowders from conventional micron-sized aluminum feedstock. Aluminum is milled in solid hydrocarbons at cryogenic temperatures, and remains in the organic liquid after recovering at ambient temperatures. The nanopowder is never exposed to any atmosphere. If it is used as an additive for liquid fuel formulations, it does not need to be specifically passivated. The prepared materials are characterized using SEM, ICP-MS, UV-VIS, laser scattering and other techniques. Combustion and ignition studies are conducted and results from experiments are discussed in detail.