SPLASHING OF A SMALL MOLTEN TIN DROPLET IMPINGING ON A SOLID SURFACE AT HIGH VELOCITY

摘要

We studied experimentally the impact of 600 micron diameter molten tin droplets on a stainless steel surface. We varied the impact velocity (10-40 m/s) and photographed impacting droplets. A molten tin droplet generator was used to produce molten tin droplets. The stainless steel substrate was mounted on the end of a rotating arm, which gave linear velocities of up to 40m/s. A CCD camera was used to photograph droplets impinging on the substrate. By synchronizing the ejection of a single droplet with the position of the arm and triggering of the camera, different stages of droplet impact were photographed. From these photographs we measured the maximum diameter to which droplet spread and recorded the velocity at which splashing was first observed. At high impact velocities (above 20 m/s) and for substrates at room temperature we did not observe formation of distinct fingers around the periphery of the drop. Instead, fragments of molten metal detached from the edge of spreading rim. We also observed that the central portion of the splat detached from the spreading rim and separated from the substrate after impact.