Thermophysical properties of molten refractory metals measured by an electrostatic levitator

Thermophysical property measurements of molten refractory metals, which are very difficult and hardly conducted with conventional methods due to their high melting temperature and risk of reaction with container walls, have been conducted using noncontact diagnostic techniques in an electrostatic levitator. This paper first briefly summarizes the procedures and methods adopted by the Japan Aerospace Exploration Agency to enable the measurements of density, surface tension, and viscosity on molten refractory metals. Typical data of superheated and undercooled liquids that would have been impossible to obtain without the use of these techniques are then reported. Specifically, density, surface tension, and viscosity of Ti, Zr, Nb, Mo, Ta, and W were successfully measured over a wide temperature range, including the undercooled region.