Surface tension of liquid Fe-Cr-O alloys

Knowledge of surface tension of iron-base alloys is important in understanding the processing of liquid steel such as behavior of inclusions and gas babble, gas-metal chemical reactions. To better understand the processing of stainless steels, we should know the surface tension of liquid Fe-Cr alloy. Several researchers have reported the surface tension of liquid Fe-Cr alloys, but those results show little agreement because of the contamination by surface-active elements that decrease the surface tension such as oxygen and sulfur in the alloy samples. In the present work, to estimate of the surface tension of liquid Fe-Cr-O alloys with a wide range of chromium content, we investigated the surface tension of liquid Fe-Cr-O alloys in some chromium content. The sessile drop method was employed in the present study. The droplet was photographed by a digital video camera at 1823K and the surface tension was calculated with the shape of the droplet. For the present, we have found that the surface tension of liquid Fe-Cr-O alloy remarkably decreases with oxygen activity at constant chromium content. Moreover the decrease of the surface tension shows much steeper slope with increasing the chromium content with respect oxygen activity. To obtain more reliable expression of relations, we will try to measure the surface tension with a wider oxygen and chromium content.