1988 Volume 52 Issue 12 Pages 1221-1227
Stoichiometrical mixture of iron, ferric oxide and silica to fayalite was prepared and mixed with 5 mass% alumina. The tablets formed by pressing the mixture were fused at 1523 K for 1.8 ks in an argon atmosphere of about 20 Pa oxygen partial pressure, and coagulated rapidly and slowly. The coagulation structures of the iron-silicate were observed and analyzed with EPMA. Under the rapid coagulation, the following phases were observed; lamellar fayalite, fine lamellar structure of the FeO-SiO2 system and slag containing fine dendritic precipitates of nonstichiometric hercynite or fine grains of magnetite. On the other hand, the phases of lamellar fayalite, dendritic or plate precipitates of nonstichiometric hercynite and slag were observed on the specimen coagulated slowly. In slow coagulation structure, the ratio of FeO to SiO2 of FeO-Al2O3-SiO2 slag is smaller than that in the rapid one, and both of the ratio of FeO to Al2O3 and the TiO2 content of plate precipitates are smaller than those of the dendritic one. The coagulation process of the iron-silicate melts was discussed on the basis of structural observations of backscattered electron images, the estimation of valency state of cation from the chemical shift of the spectra of characteristic X-rays, and the determination of oxygen content using the analyzing crystal, LDE1.
