Surface tension measurements of industrial steels - DLR contribution to ThermoLab-Midterm Report

Industrial alloys are generally multi-component systems with volatile and highly reactive components. Consequently, their processing in the liquid state requires special precautions. Therefore, the existing electromagnetic-levitation device with a high-vacuum chamber, designed for surface tension measurements, was modified and improved for this task. 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 - 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 : the CORUS - low alloyed steel and the SANDVIK - high alloyed steel ( SAF 2507 )