Size evolution during laser-ignited single iron particle combustion

To further our understanding of iron particle combustion, especially in the liquid state, insitu optical measurements are performed for size evolution and temperature laser-ignited particles a narrow range around 45–55μ m. The is monitored by high-speed shadowgraphy system, probed using two-color pyrometer synchronized with system. Before reaches peak temperature, its diameter grows linearly elapsed time. Near three types behavior detected, namely, smooth transition, micro-explosion, rapid inflation. For reach maximum values at same time, thereafter remains constant, while drops until solidification oxide droplet. micro-explosion inflation clearly indicate towards quick gas release inside particle. ambient oxygen concentration has strong effect on growth rate before but no influence final size. measured relative suggests that been fully oxidized degree oxidation could be higher than FeO. At onset solidification, occurs again, resulting second or burst already inflated particles. This dissolved least more needed to form solid Fe3O4, process accompanied gaseous via phase transition: L2 ⟶ Fe3O4(s) + O2(g) 1855 K, where represents excess oxygen.