Surface tension is an essential parameter that defines many aspects of materials processing. In particular, at high temperatures, surface tension data of metals is missing. Due to the challenges during high temperature measurements, mainly extrapolated or theoretical data are available. Therefore, an adaption of the falling oscillating droplet method is suggested to derive surface tension values of liquid steel surfaces. A spherical droplet was pre-positioned on plastic foil to be melted by a laser beam. During falling, high-speed imaging could record the oscillations and related frequency spectra were derived. Based on extracted characteristic frequencies, surface tension values were obtained comparing different theoretical models and adaptions to impacts of gravity, asphericity and viscosity of the material. The method was shown to give reasonable values of surface tension when accounting for gravity impacts.
Full text license: CC BY-NC-ND 4.0;
Funder: Swedish Research Council (2020-04250);