The study on Heat Transfer and Solidification of Uniform Droplet formed from Jet Breakup

摘要

An experimental device capable of producing uniform metal droplet stream and electric charging and deflecting has been developed.Uniform spherical powder of 180μm in diameter was obtained after cooling and solidification.Numerical models of heat transfer and solidification of droplets were established.The thermal history including solid fraction of droplets in uniform droplet spray process were calculated.Under the common processing conditions,the cooling rate of a droplet of 180μm diameter is of the order of 103-104°C/s.To obtain homogeneous and dense preforms,the substrate should be positioned at a distance of l.l-l.3m from the nozzle.