Effect of Nanocomposite Synthesis on the Combustion Performance of a Ternary Thermite

摘要

Nanocomposite thermites are attractive materials for their diverse applications from metallurgy to ordnance technologies.While there are a plethora of combinations of fuel and oxidizers,this work shows that the composite's overall performance is intimately tied to how the fuel and oxidizer are prepared and combined.Comparison of the combustion velocities of two separate ternary mixtures of Al-Fe_2O_3-SiO_2,one prepared in situ using sol-gel processing and the other prepared by physically mixing discrete nanoscale particles,demonstrated different burning behaviors as a result of preparation technique.The stoichiometry of the two sets of thermite was varied to examine the influence of SiO_2 on combustion velocity as a means to control the reaction behavior.For pure Fe_2O_3+Al reactions,results show that the sol-gel synthesized materials (40 m/s) exhibit increased velocities over the physically mixed materials (9 m/s) by approximately 4 times.This trend is not observed,however,upon addition of SiO_2 to the thermite mixture;ternary thermites with 40 wt % SiO_2 showed decreased bum velocities of 0.02 m/s for sol-gel prepared thermites compared to 0.2 m/s for their physically mixed counterparts.The observed trends are believed to be caused by the unique mixing between the Fe_2O_3 and SiO_2 phases resulting from the two synthesis techniques.