ヘマタイト単結晶の還元挙動におよぼす添加 Na, K および Ca 化合物の影響

概要

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The effect of the presence of K_2O, Na_2O, and CaO in Fe_2O_3 on its reduction behavior was investigated. Platelets of Fe_2O_3 single crystals were prepared by the flux method using Na_2B_4O_7 glass as a flux. The size of the crystals was approx. 3 mm in width and 0.3 mm in thickness. In order to make Fe_2O_3 react with K_2O, Na_2O, and CaO, small amounts of Na_2CO_3, K_2CO_3 and CaCO_3 powders were placed on the flat plane (0001) of Fe_2O_3 and heated at 1100∿1300℃ in air. It was confirmed by EPMA that reaction products of those substances were formed on some parts of the (0001) plane of Fe_2O_3. The Fe_2O_3 crystals were reduced at 750℃ in CO and H_2 streams, and surface structures were observed by SEM. The results obtained were as follows. When alkaline metals (as Na_2O, K_2O) were present in Fe_2O_3 abnormal swelling took place during reduction. It was considered that the swelling was caused by the net effects of (1) cracking of the crystal at early stage of the reduction (2) fibrous iron formation and (3) carbon deposition on the reduced iron. The fibrous iron formation was also observed in the grain boundary of calcium ferrite.
社団法人日本鉄鋼協会の論文
1976-10-01