1986 Volume 27 Issue 5 Pages 372-381
The purpose of the present work is to investigate the contamination of molten iron with crucible materials during the melting process.
High purity iron was melted at 1873 K for 900 s in an alumina crucible by use of a tungsten-mesh heater furnace, and the ingot was sectioned for chemical analysis. The cross section of the ingot was deep-etched electrolytically and was observed with a scanning electron microscope. From the deep-etched cross section, inclusions were extracted onto a carbon film and their chemical composition was determined with an analytical electron microscope.
The results are as follows:
(1) Iron was contaminated with silicon during the melting process. The silicon content of the iron in-got depended on the silica content of the crucible.
(2) By use of an alumina crucible which contained less amount of silica, 0.005 mass%, the silicon contamination of melt was suppressed.
(3) The silicon content of inclusions depended on both the silicon and oxygen contents of ingots. It can be estimated by both the postulated equilibria which were obtained in terms of Turpin and Elliott’s treatment and the change in melt composition during solidification.
(4) The composition of inclusions can be also presumed from a predicted Fe–Si–O system phase diagram.
