Laser ignition properties of composite nanometric energetic materials

Laser ignition delay experiments were conducted in order to better understand the effects of thermal and chemical properties on ignition mechanisms for energetic materials. A Nd: YAG laser (10 ms, ~2 J, 3-mm beam diameter, 1064-nm wavelength) was used to heat the top surface of a reactive material powder, and ignition delay was calculated as the difference between first light of the laser's flash lamp and the sample. In the compositions tested, nanometric aluminum (Al) was used as the fuel and combined stoichiometrically with an oxidizer [copper oxide (CuO), iodine pentoxide (I₂O₅), polytetrafluoroethylene (C₂F₄), molybdenum trioxide (MoO₃), tungsten trioxide (WO₃), or iron oxide (Fe₂O₃)]. Results show that ignition delays for asymmetrical heating are strongly affected by thermal properties. A key result is that ignition delay was found to be inversely proportional to the molar heat capacity of the oxidizer.