The Development for In-situ Observation of Chemical Reaction between Solid and Solid

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The reduction of iron oxides has been one of the most frequently studied topics in iron smelting. Transmission electron microscope (TEM) was used for in-situ observation of microscopic analysis. But the applications were mainly focused on the gas-solid reaction such as using CO or H as reductant. The coke i.e. solid state carbon is used in iron industry and the solid state carbon is also important reductant. The aim of this study is to realize in-situ observation of the chemical reaction between solid and slid such as carbon and iron-oxides in TEM. We used wustite as an iron-oxide and carbon-deposition was applied to get solid/solid boundary between carbon and wustite. The fracture surface was applied to get the clean surface of wustite. The carbon was deposited on the fracture surface to contact with wustite. The preparation of the specimen was done with the size of thin foil of TEM sample. In-situ observation was performed at elevated temperature. The precipitates were generated at the boundary of wustite and carbon and grew into the carbon layer at the higher temperature about over 873K. The energy dispersive X-ray spectroscopy (EDS) showed that the precipitates were pure iron. The effect of lime and alumina as impurities were also investigated. The increase of the concentration of impurities caused suppress the precipitation and growth of Fe even up to 1073K. These results indicated that the Ca and Al played as barriers to the reduction of FeO.