关键词: 烧结气氛;镁铁铝复合尖晶石;物相组成;显微结构

Abstract: Using fused magnesia,activated alumina,iron oxide and graphite as raw materials,ingredients according to mass ratio of 24:61:10:5,specimens of φ20 mm × 10 mm were prepared,which were treated at a high temperature of 1550 ℃ for 3 h under three different sintering atmospheres,such as air atmosphere, reducing atmosphere (buried carbon ) and nitrogen atmosphere. The samples were characterized by XRD,SEM,EDS and so on. The results show that under three different sintering conditions,magnesia-iron-aluminum composite spinel with different iron contents are synthesized. Under the condition of reducing atmosphere sintering,the iron in the magnesia-iron-aluminum composite spinel phase is +2 valence,at the condition of air atmosphere and nitrogen atmosphere sintering,the iron in the magnesia-iron-aluminum composite spinel phase is +3 valence. The distance between the crystal faces of the sample increases with the iron solubility increases. Compared with the other two sintering atmospheres, the sintering condition of the reduction atmosphere has large grain size and high synthesis rate.

Key words: sintering atmosphere;magnesia-iron-aluminum composite spinel;phase composition;microstructure