Enhancement of the ignition and combustion performance of nano-aluminum: the effect of cryolite

To study the effect of cryolite (Na 3 AlF 6 ) on the ignition and combustion performance of nano-aluminum (n-Al), composites of n-Al with varying amounts of Na 3 AlF 6 were prepared by physical mixing. By using TG–DSC–MS, TG–DTA, SEM–EDS, XRD, and a high-speed camera, the thermal characteristics, activation energy, ignition delay time, combustion phenomena, and reaction products of the materials were examined. The results show that there was a pre-ignition reaction between n-Al and Na 3 AlF 6 . The exotherm was roughly double that of n-Al after the addition of Na 3 AlF 6 . The n-Al gas–solid reaction had lower activation energy. The ignition and combustion tests reveal that Na 3 AlF 6 decreased n-Al's ignition delay time to 50 ms, whereas an excess of Na 3 AlF 6 had a negative effect. The n-Al with the Na 3 AlF 6 addition displayed more violent combustion events during combustion. Analysis of the reaction products demonstrates that Na 3 AlF 6 reacted with Al 2 O 3 to generate aluminum oxyfluoride complex ions, which then reacted with Al 2 O 3 to form Na 2 Al 2 x O 3 x +1 (Na 2 Al 22 O 34 ) and AlF 3 . The addition of Na 3 AlF 6 effectively enhanced the ignition and combustion performance of n-Al, which is beneficial to the optimization of Al-based energetic nanocomposites. Graphical Abstract Nano-aluminum with varying additions of cryolite was prepared by physical mixing, and the effect of cryolite on the ignition and combustion performance of nano-aluminum was analyzed