2009 Volume 95 Issue 1 Pages 86-95
The fine iron ingot was developed by the microwave oven heating using the iron sand and the charcoal powder. In the initial stage in which the heating time was 3–6 min, the iron sand changed into the lump consisting of Fe, FeO, Fe2TiO4 and Fe2SiO4. By further increasing the heating time, the iron ingot with a smooth surface and a metallic luster was formed, since the fine Fe particles in the lump aggregated and the Fe particles separated from the other constituent phases. The yield on the iron ingot formed from the iron sand was almost 50 mass%, irrespective of the weight of the iron sand. It is also found that the microstructure in the fine iron ingot changed by the microwave heating time, from the cementite and the pearlite, through the graphite and the pearlite, to the cementite and the pearlite. This suggests that the carbon content in the fine iron ingot increased by the carburization, when the fine iron ingot was just formed. However, the carbon content decreased by the decarburizing reactions with increasing the heating time, since the charcoal powder decreased, and the contact with the charcoal powder was inhibited by the slag.