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 non-fully spreading melt on the atomizing cup. The model shows that the melt can disintegrate prematurely before reaching the edge of the cup when the dynamic contact angle of the melt exceeds a critical contact angle. The critical contact angle is very small for a flat disc but increases markedly with increasing slope angle of a cup. The critical contact angle also increases with increasing melt flow rate and cup rotation speed. The model gives a good insight into the atomization mechanism and explains well the phenomena observed in centrifugal atomization, including the conditions of the occurrence of the three atomization modes and the existence of an optimum melt flow rate, cup radius, cup slope angle and cup rotation speed for achieving small droplet sizes.
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