Numerical Investigation of Charge Effect on Collective Growth of Iron Nanoparticles Generated in Arc Welding

摘要

Charge effect on collective growth process of iron nanoparticles, which are primary particles of fume generated in arc welding was investigated numerically. The result clearly showed that charging of nanoparticles was a crucial factor for the collective growth process. The model used in this study has several advantages. It can treat particles with multiscale diameters ranging from sub nanometers to a few hundred nanometers. It can also express particle size distributions with various shapes. It can take account of homogeneous nucleation, heterogeneous condensation, coagulation process among particles and particle charge simultaneously. The numerical calculation by this revealed that nuclei generated by homogeneous nucleation grew mainly by heterogeneous condensation. The effect of coagulation was smaller because almost all of the nanoparticles have charges and repelled each other by Coulomb's force. When the model did not take charge effect into account, nanoparticles exhibited larger sizes. The numerical calculation considering charge effect obtained a particle size distribution which showed a good agreement with that obtained by an experiment.