A Sessile Droplet Study of Iron-Carbon-Sulfur Alloys on an Alumina Substrate

摘要

Reactions at interfaces such as inclusion separation and refractory attack are extremely important for steel refining. These phenomena involve study of interfacial tensions and contact angles at the heterogeneous interface. In the present work, the contact angle between molten iron and alumina substrate and the surface tension of iron alloys containing different amounts of sulfur and carbon were determined experimentally using the Sessile Drop Technique. A CCD video-camera was utilized to image the melt profile. The contact angle and surface tension were calculated from computer generated solutions of the Young-Laplace equation. In the present study, contact angles and surface tensions of molten iron alloys with different sulfur contents in the range of 0.0092-0.651 wt% and also iron-0.035 wt% sulfur containing 0.5-4.0 wt% carbon were measured at 1873K in an argon-5% hydrogen gas atmosphere. The addition of sulfur to liquid iron caused a decrease in both the contact angle between liquid iron and alumina substrate and the surface tension of molten iron. On the other hand, addition of carbon to liquid iron at constant sulfur content caused an increase in the contact angle between molten iron and alumina substrate and also the surface tension of iron-carbon-sulfur alloys. Considering the data for iron alloys with 0.035% sulfur and various carbon contents, it was concluded that carbon decreases the surface tension of the liquid iron by increasing the activity of sulphur in the bulk, however carbon itself increases the surface tension of molten iron and the over-all effect is that the surface tension increases with carbon content.