Studies that incorporate nano-scale or ultrafine aluminum (Al) as part of an energetic formulation demonstrate significant performance enhancement. Decreasing the fuel particle size from the micron to nanometer range alters the material's chemical and thermalphysical properties. The result is increased particle reactivity that translates to an increase in the combustion velocity and ignition sensitivity. Little is known, however, about the critical level of nano-sized fuel particles needed to enhance the performance of the energetic composite. Ignition sensitivity and combustion velocity experiments were performed using a thermite composite of Al and molybdenum trioxide (MoO 3) at the theoretical maximum density (TMD) of a loose power (5% TMD) and a compressed pellet (50% TMD). A bimodal Al particle size distribution was prepared using 4 or 20 m diameter Al fuel particles that were replaced in 10% increments by 80 nm diameter Al particles until the fuel was 100% 80 nm Al. Results show that with only 20 % nano-Al content, the mixtures showed reduced ignition delay times by up to two orders of magnitude (i.e., from 2205 to 56 ms for 100 %m Al with MoO 3 to 80 % m / 20 % nm Al with MoO 3, respectively). The combustion velocity was shown to dramatically increase as more nano-Al particles replace m Al particles within the mixture. This increasing trend was attributed to incomplete reactions with the m Al particles or significantly slower reactions such that cooling occurs.
|State||Published - 2005|
|Event||41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit - Tucson, AZ, United States|
Duration: Jul 10 2005 → Jul 13 2005
|Conference||41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit|
|Period||07/10/05 → 07/13/05|