화학공학소재연구정보센터
Atomization and Sprays, Vol.10, No.1, 25-46, 2000
Gas flow effects on twin-fluid atomization of liquid metals
Twin-fluid atomization by means of free-fall atomizers is a common process technology in metal powder production and especially in metal spray forming. The latter is a process route for producing near-net-shaped preforms with excellent material properties. Here, disintegration of the molten metal results in a characteristic particle size, momentum, and thermal energy distribution in the spray, which strongly affects the behavior and efficiency of the spray forming process. The gas nozzle arrangement in the free-fall atomizer consists in most applications of a number of discrete jets. Spreading and interaction of the individual gas jets result in a characteristic transsonic gas flow field in the vicinity of the atomization area. Changes in the gas momentum distribution in the atomization area are discussed, dependent on the geometric arrangement of the jets and the formation of the gas nozzle contours (converging or converging/diverging). The particle size distribution in the spray is analyzed for a model fluid and a metal melt. Some design criteria for free-fall atomizer nozzle arrangements with efficient liquid metal atomization are given.