Evaporation of Cu and Sn from Induction-stirred Iron-based Melts Treated at Reduced Pressure

The evaporation of Cu and Sn from iron-based melts at reduced pressure has been investigated. The experimental work was carried out in a laboratory-scale vacuum induction melting (VIM) furnace. The effects of (1) chamber pressures of 1 to 100 Pa, (2) melt temperatures of 1 673 to 1 873 K, (3) different melt compositions and (4) two different stirring intensities of the metal bath on the evaporation rate of Cu and Sn, respectively, were studied. It was found that the evaporation of Cu represents a reaction of first order with respect to Cu content of the melt. The evaporation of Sn is represented by a first order rate law, too. Under the same experimental conditions, the evaporation rate of Cu exceeds that of Sn. The rate controlling steps of evaporation are discussed. The optimal conditions of vacuum refining iron melts with respect to Cu and Sn were determined. Recommendations for the design of new vacuum treatment equipment are also given.