Ignition and combustion characteristics of aluminum-based fluorine-containing composite powder

•An in-depth comparative study of three different aluminum-fluorides.•Fluorides can significantly raise the ignition and combustion performance of Al.•The promoting effect on aluminum combustion can be ranked: FG > PTFE > MgF2.•The Al2O3 shell underwent pre-ignition reaction with fluorides. To improve the combustion characteristics of micron-sized aluminum (Al) powder, a composite powder was prepared by doping a small amount (15 wt%) of magnesium fluoride (MgF2), polytetrafluoroethylene (PTFE), and fluorinated graphite (FG) into the aluminum powder through solution dispersion method. The physical phase composition, micro morphology, thermal reactivity, and combustion performance of the composite powders were also characterized. The findings suggest that the promoting effect of the three fluorides on aluminum combustion can be ranked in the following descending order: FG > PTFE > MgF2. The fluorides can to erode the Al2O3 shell layer directly, thus creating cracks and reaction pathways for the Al core enclosed within the shell. Moreover, the gasification of AlF3 within the combustion products can escape from the surface of Al particles and promote the oxidation combustion of the exposed aluminum, which enhances the diffusion reaction on the active aluminum surface. [Display omitted]