Computational Combustion Study of Reactive Metal Nanoparticles as Solid Additives

Energetic nanoparticles, those particularly including Ti-Al-Mg components, have attracted significant interest due to their potential applications in combustible fields. Ti-Al-Mg reactive materials typically consist of a mixture of titanium (Ti), aluminum (Al), and magnesium (Mg) in varying proportions. The combination of these elements offers a favorable balance between energy density and safety, making them suitable for a range of applications. Previous studies have explored the synthesis, characterization, and applications of Ti-Al-Mg reactive materials. For instance, Belal <i>et al.</i>¹ investigated the burning rate of mechanically activated Al-Mg composites. Their research highlighted mechanical activation of Al–Mg nanoparticles decreases the ignition temperature of the particles and enhances their reactivity. Furthermore, Kochetov and Sytschev² explored the influence of Mg content on the thermal properties and reactivity of Ti-Al-Mg composites. Their findings demonstrated that the interaction between Mg, Al and Ti can result in a lightweight composite suitable for applications at high temperatures, which is crucial for tailoring their performance in specific applications. While previous experimental studies have successfully investigated combustion performance of those reactive materials, molecular-level understanding of thermal behaviors of Ti-Al-Mg nanoparticles has yet to be achieved. Here we perform reactive molecular dynamics simulations based on ReaxFF^3,4 to investigate initial oxidation processes of three nanoparticles (Ti, Al, and Mg). Our RMD simulations reveal molecular-level reaction steps for the combustion process of the reactive nanoparticle with and without an aggregation effect. Our RMD simulations will help guide an experimental design of a novel metamaterial using Ti-Al-Mg composites, providing a valuable input for the community of solid-fuel propellants.<br/><br/><b>References</b><br/><br/>[1] Belal, Hatem, Chang W. Han, Ibrahim E. Gunduz, Volkan Ortalan, and Steven F. Son. "Ignition and combustion behavior of mechanically activated Al–Mg particles in composite solid propellants." Combustion and Flame 194 (<b>2018</b>): 410-418.<br/>[2] Kochetov, N. A., and A. E. Sytschev. "Effects of magnesium on initial temperature and mechanical activation on combustion synthesis in Ti–Al–Mg system." Materials Chemistry and Physics 257 (<b>2021</b>): 123727.<br/>[3] Hong, S. and van Duin A. “Atomistic-Scale Analysis of Carbon Coating and Its Effect on the Oxidation of Aluminum Nanoparticles by ReaxFF-Molecular Dynamics Simulations.” J. Phys. Chem. C. 120 (<b>2016</b>) 9464−9474<br/>[4] Senftle, T. P.; Hong, S.; Islam, M. M.; Kylasa, S. B.; Zheng, Y.; Shin, Y. K.; Junkermeier, C.; Engel-Herbert, R.; Janik, M. J.; Aktulga, H. M. “The ReaxFF Reactive Force-Field: Development, Applications and Future Directions.” npj Comput. Mater. 2 (<b>2016)</b>, 15011.