Ignition and Combustion Characteristics of Micro-Aluminum and Nano-Aluminum Mixture

While prior studies focus on individual aluminum powders, the combustion behavior of mixed nano- and micron-sized aluminum particles remains unclear. This work investigates combustion characteristics of aluminum powders with different particle size combinations (29 µm, 15 µm, 1 µm, and 100 nm) under two conditions: a pure composition and a mass ratio of 72.2% micron-sized particles to 27.8% nano-sized particles. Additionally, the combustion characteristics of aluminum powders with best combustion performance particle size combinations were analyzed under six different oxidation environments (O₂, N₂, and CO₂) and various packing densities. The results indicate that the mixed aluminum powder with a 72.2% mass ratio of 29 µm particles and 27.8% mass ratio of 100 nm particles exhibits the best overall combustion performance. Among the six oxidizing atmospheres, the mixed aluminum powder demonstrated the highest combustion performance in a pure oxygen environment. The combustion performance of mixed aluminum powder is most effective at a density of 2.9 g/cm³. The combustion performance of aluminum powder is significantly enhanced when nano- and micron-sized aluminum powders are mixed. This improvement is attributed to the synergistic benefits of combining the two sizes, where nano-sized aluminum, with its high specific surface area, facilitates rapid oxidation kinetics and intense combustion, while also generating more gaseous products that boost thrust. Conversely, micron-sized aluminum provides effective heat conduction and stability, acting as a thermal reservoir that prolongs combustion duration and mitigates agglomeration. This system enables quick ignition and a balanced release of energy, optimizing both reaction efficiency and thrust stability.