EMF Sensor Control in Vacuum Decarburization and Deoxidation of Steel Melts

Abstract

Newly designed electrochemical sensors were used for continuous measurements of oxygen activity in 4 kg vacuum induction melts at 1600°C. It is shown that the activity of oxygen can be recorded over at least 3 h under a vacuum of 0.001 bar. A good agreement between the values derived from EMF measurements and those from chemical analysis was obtained. The rate of decarburization is strongly affected by the initial concentration of oxygen in the melt. He process is controlled either by diffusion of carbon to the interface of melt/gas, if the melt is sufficiently supplied with oxygen, or by oxygen transfer to the boundary of melt/gas at the beginning of decarburization. The resulting mass transfer coefficients or carbon and oxygen are 0.01 cm/s, respectively.