Abstract: Flame spray pyrolysis, benefitted from its compact equipment and straightforward setup, is well‑suited for in‑situ resource utilization in extraterrestrial environments, supporting sustainable deep‑space exploration. The micro‑explosion phenomenon in the flame-synthesis process promotes gas‑phase transformation, enabling the production of uniform, high‑purity functional nanoparticles. In this study, a single‑droplet generator integrated into a multi‑element diffusion flat‑flame burner was designed and combined with high‑speed shadowgraph technique to investigate the micro‑explosion of precursor droplets traversing the flame front. Using aluminum nitrate as the precursor, ethanol as the solvent, and 2‑ethylhexanoic acid as the additive, the micro‑explosion behavior was examined at varying additive concentrations and flame temperatures. The results show that the probability of micro‑explosion increases with higher flame temperatures and higher additive concentrations. Furthermore, liquid‑phase reactions within the precursor were found to promote micro‑explosion. This study aimed to systematically elucidate the core mechanisms of droplets micro-explosion and pave ways for precise control of atomized flame synthesis.

Key words: flame synthesis, multicomponent precursor, single-droplet generator, multi-element diffusion flat-flame burner, microexplosion