Status of the Electrostatic Levitation Furnace in the ISS - Surface Tension and Measurements

This article is a follow-up report of the status of the electrostatic levitation furnace research activities onboard the International Space Station (ISS). Capability of drop oscillation to measure surface tension and viscosity of molten samples was evaluated using Al2O3. Experimental results were consistent with the values measured with a ground-based electrostatic levitator as well as some data in literature, which proved that surface tension and viscosity could be measured by drop oscillation method in microgravity. This technique was then applied to molten terbium oxide (Tb2O3) whose surface tension and viscosity have not been reported. Measured surface tension could be expressed as gamma(T) = 733.4-3.9x10(-2)(T-T-m) (10(-3)N/m), where T-m=2683 K and the viscosity as eta(T)= 0.33exp[9.75x10(4)/(RT)] (10(-3)Pa.s) over the 2745 to 3259 K temperature span.