低酸素分圧下での赤色粘土の焼成時における酸素の放出と鉄の化学状態変化

概要

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A red clay body containing 7 mass% Fe_2O_3 was fired in a mildly reducing atmosphere(Ar-O_2, Po_2=0.1kPa)and its blackening and bloating mechanisms were investigated. Reduction of Fe_2O_3 started at around 1100℃, accompanied by the blackening of the clay body. Bloating was caused by the entrapment of oxygen that was released by iron oxides in closed pores, the formation of which started at about 1200℃. Fe^<2+> that was formed in the clay body during the heating process migrated toward the surface layer during the cooling process, resulting in the enrichment of Fe in the surface layer. The results of thermodynamic calculations suggested that oxygen evolution was caused or at least assisted by the reaction of iron oxides with Al_2O_3 to form FeAl_2O_4, a stable spinel.
社団法人日本セラミックス協会の論文
2000-08-01