In-situ light extinction nano-oxide volume fraction measurements during single iron particle combustion

In-situ measurements of the volume fraction of nanoparticles generated during the combustion of single iron particles were conducted using a high-speed light extinction method. The process of nanoparticles generation from iron particles burning under conditions of 21% oxygen concentration and ambient temperatures of 1400 K and 1850 K can be divided into three stages: acceleration of productivity, stable productivity, and continuous growth of volume fraction after the cessation of nanoparticles generation on the iron particle's surface. The productivity of nanoparticles in stage 2, which is proportional to the particle diameter, suggests that the nanoparticles generation process in this stage may be influenced by the outward diffusion of gaseous Fe and FeO. Approximately 2% to 4% of iron is converted into nanoparticles after combustion, and the conversion rate decreases with increasing particle diameter. Accurate values of the refractive index of iron and its oxides at high temperatures and in the liquid phase will contribute to improving the accuracy of the light extinction measurement since those values significantly affect the measured results of the volume fraction of nanoparticles.