A dynamic technique for measuring surface tension at high temperatures in a microgravity environment

Abstract

The feasibility of a dynamic technique for measuring surface tension of liquid metals at high temperatures in a microgravity environment is considered. The basic method involves heating a tubular specimen resistively from ambient temperature through its melting point in about l s by passing an electrical current pulse through it, while simultaneously recording the pertinent experimental quantities. Static equilibrium for the molten specimen may be achieved (at least for a short time) in a microgravity environment by splitting the current after it passes through the specimen tube and returning a fraction along the tube axis and the remaining fraction outside the specimen. Adjustments to the current split enable a balance between the magnetic and surface tension forces acting on the specimen. Values for surface tension are determined from measurements of the equilibrium dimensions of the molten specimen tube, and the magnitudes of the currents. Preliminary rapid melting experiments, performed during microgravity simulations with NASA's KC-135 aircraft, yield a value for the surface tension of copper at its melting point which is in reasonable agreement with literature data.