Frank Schmidt-Hohagen

Thermophysical property measurements of liquid metals by electromagnetic levitation

Electromagnetic levitation is a useful technique for containerless processing of liquid metals. In combination with non-contact diagnostic tools it can be used for completely non-invasive measurements of thermophysical properties of metallic melts. Considerable progress has been made in this field in recent years. This paper reviews methods and results, including those obtained in microgravity.

Surface tension measurements of industrial iron-based alloys from ground-based and parabolic flight experiments: Results from the thermolab project

Surface tension measurements of different alloys of the Al-Ni system, performed both under reduced gravity conditions in parabolic flights and on ground by conventional techniques, are presented. The alloys compositions were selected on the basis of the intrinsic compound forming tendency with the aim to allow a sensitive test of model predictions.

Surface tension measurements of industrial alloys

Industrial alloys are generally multi-component systems with volatile and highly reactive components. Consequently, their processing in the liquid state requires special precautions. Therefore, an existing electromagnetic-levitation device with a high-vacuum chamber, designed for surface tension measurements, was modified and improved. For the measurements of the surface tensions with the help of the oscillating drop technique the temperatures and the video sequences of the levitated, molten alloy were recorded without contact by pyrometer and by high-speed camera, respectively. This method yields the frequencies of the surface oscillations of the sample around the equilibrium shape and - using the modified Rayleigh law - eventually the values of the surface tension. With the help of this method two commercial industrial steels were processed in the new EML-apparatus for ESA`s Thermolab project [1]. The results of these measurements are presented and discussed