烧结气氛对合成镁铁铝系复合尖晶石的影响

以电熔镁砂、活性氧化铝、氧化铁和石墨作为原料,按质量比24:61:10:5进行配料,制得φ20 mm×10 mm的试样,在空气气氛、还原气氛(埋碳)、氮气气氛三种不同烧结气氛条件下,1550℃ ×3 h高温处理.采用XRD、SEM、EDS等手段对烧后试样进行了表征.分析结果表明:在三种不同烧结条件下,都合成了铁含量不同的镁铁铝复合尖晶石;在还原气氛烧结条件下,试样中镁铁铝复合尖晶石相中铁是+2价的,在空气气氛和N2气氛烧结条件下,试样中镁铁铝复合尖晶石相中铁是+3价的;试样的晶面间距随铁固溶量的增加而增大;还原气氛烧结条件相比其他两种烧结气氛,晶粒尺寸大且合成率高.

Effect of Sintering Atmosphere on Synthesis of Magnesia-Iron-Aluminum Composite Spinel

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.