Burning Times of Select Aluminum Alloy Particles

In this work, we study metal particle combustion of select high aluminum content alloys. This study uses a particle-aerosolizing apparatus to feed particles into a CO2 laser and ignite them. While most other studies investigate pure Al, this study investigates aluminum alloy particles to determine how the alloy element effects their combustion behavior. These alloys are aluminum-gallium (Al-Ga), aluminum-indium (Al-In) and aluminum-lithium (Al-Li). By capturing high-speed video of these particles, the ignition and combustion processes of these particles are studied. Two key findings were identified in this study. First, Al particles surprisingly have shorter burn times than Al alloy particles. Second, alloy particles show a greater number of ignition events outside of the laser beam, indicating that the alloy element enhances ignition where a pure Al particle would have quenched. The fact that Al alloys have longer burning times indicates that alloys have a slower energy release rate than pure Al. However, in propellants the alloy particles enhance the burning rate. Therefore, our findings indicate that higher burning rates observed in Al-alloy propellants stems from enhanced particle ignition rather than shorter burning times.