Transient combustion behavior and oxidation characteristics of iron particles under ammonium perchlorate-assisted conditions

Abstract

To support carbon neutrality and carbon peaking goals, recyclable metal fuels have attracted considerable attention owing to their clean combustion characteristics and energy storage capability. Among them, iron (Fe) particles exhibit significant advantages due to their abundant availability and high potential for cyclic utilization. However, the transient combustion response of Fe particles and oxidation characteristics remain insufficiently understood. In this study, the combustion behavior of Fe particles under ammonium perchlorate (AP)-assisted conditions were investigated using a CO 2 laser ignition platform. By combining high-speed imaging with X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size analysis (PSA), the particle evolution, final phase composition, product morphology, and particle-size distribution were systematically elucidated. The combustion of Fe particles exhibits unsteady and multistage evolution characteristics. The particle remains largely intact during the initial stage, followed by oxide-shell instability-induced micro-explosions and particle fragmentation, and ultimately transitioned into a molten state in the combustion stage. High-temperature oxidation experiments further demonstrate the oxidation of Fe particles in air. Fe oxides with different valence states and residual metallic Fe under different temperatures coexist due to oxygen diffusion limitations and localized non-equilibrium oxidation. This study provides experimental evidence for understanding Fe particle combustion in heterogeneous reactive environments and establishes a foundation for their application in clean thermal energy systems.