Analysis of flow development in centrifugal atomization: Part I. Film thickness of a fully spreading melt

Centrifugal atomization of metal melts is a cost-effective process for powder production and spray deposition. The properties of the as-produced powder and deposit are determined primarily by the characteristics of the atomized droplets, which in turn are largely dependent on the flow development of the melt on the atomizer. This paper develops a model for analysing the flow development of a fully spreading melt on and off the atomizing cup. The model can be used to calculate the velocity and film thickness of the melt as a function of melt volume flow rate, cup rotation speed, cup radius and cup slope angle, as well as to predict the trajectory of the spray off the cup. The model implies that the disintegration of a fully spreading melt takes place in the region just off the cup edge and the film thickness at the cup edge is a critical factor determining the sizes of the resultant droplets. The film thickness at the cup edge is shown to decrease with decreasing volume flow rate, with increasing cup rotation speed, with increasing cup radius and with decreasing cup slope angle.