Reactive molecular dynamics study of oxidation of aggregated aluminum nanoparticles

Oxidation behavior of aggregated aluminum nanoparticles (Al-NPs), specifically the combustion propagation, is studied, when only part of the aggregated Al-NPs is heated to 1100 K and the rest of the system is kept at 300 K. Here, multi-million atoms molecular dynamics (MD) simulation reveals the sintering/coalescence phenomena for the different diameters (D = 26, 36 and 46 nm) aggregated systems. Various consuming rates of core aluminum are investigated for different layers and different diameters aggregated systems. The formation of Al<inf>2</inf>O<inf>3</inf> fragments outside the shell (the largest covalently bonded aluminum-oxide cluster) structure is confirmed from AlO and AlO<inf>2</inf> intermediates. The smaller size of Al-NPs results in faster trend of transition from Al-rich to O-rich for most outside small clusters. However, more core aluminum reacts with shell oxygen leads to faster decreasing of the ratio of O/Al in the shell fragment for larger Al-NPs system.