Numerical simulation of temperature field on nanostructured agglomerated powder during plasma spraying

A numerical simulation model for analyzing the temperauture field of the nanostructured agglomerated Al₂O₃-13% TiO₂ powders during plasma spraying process was established based on the ideal assumption of the nanoparticles stacking structure and conversion of the feedstock thermal physical parameters. The effects of the feedstock diameter, spray distance and temperatuer of jet nozzle outlet on melting process of powders were studied. Meanwhile, experiment of plasma spraying using nanostructured agglomerated powders was carried out. The results showed that the size distribution of the powders should not be too broad and a suitable spray distance, as well as temperatue of jet nozzle exit was necessary to gain a proper and uniform molten state of the feedstock. During plasma spraying, the region less than 1840℃ where nanoparticles were retained, and the region between 1840℃ and 2045℃ where TiO₂ nanoparticles were selective melted and the region more than 2045℃ where nanoparticles were fully melted.