FORMATION OF HIGHLY ELONGATED FLAKES BY SPLAT QUENCHING DROPLETS ON AMOVING SUBSTRATE AT A SMALL-ANGLE

In this study, highly elongated Al-12wt.%Si alloy flakes were produced by splat quenching centrifugally atomized droplets on a moving substr ate at a small angle. The dimensions of flakes obtained under various operating conditions were measured and the influences of droplet size and impingment velocity on the flake morphology were investigated. The extension factor defined by the ratio of flake length (or width) to d roplet diameter was used to represent the spreadability in the corresp onding direction. The results showed that both increasing droplet size and increasing impingement velocity increased the extension factor in the transverse direction but decreased it in the longitudinal directi on. As a result. the length-to-width ratio was reduced together with t he decreased flake thickness to give a larger aspect ratio. The aspect ratio of as-produced flakes ranged from 200 to 800.