Impact of Boiling on Surface Tension of Steel

It is typically assumed that surface tension decreases with increasing temperatures. Around the melting temperature of steel, this seems to be quite correct. However, it is difficult to measure or model surface tension around boiling temperatures of metals, although those values play a crucial role in many processes. Therefore, this work used a simple pair-interaction model to derive surface tension values to explain how surface tension can increase with temperature above the boiling temperature. Different surface atom removal patterns were applied. Simulation results of surface tension were compared with experimental surface tension measurements on vapor channel walls. It was found that surface tension seems to depend on the way atoms leave the surface and how they rearrange on the surface. It is further indicated that second layer removal is necessary to describe the surface tension at extensive boiling conditions.