Abstract: Spinel-periclase specimens were prepared using three kinds of spinels (magnesia-rich spinel,alumina-rich spinel and bauxite-based magnesia-rich spinel) and sintered magnesia as main raw materials,adding a small amount of silica fume and firing at 1 550 ℃ for 3 h.The effects of different kinds of spinels on the sintering properties of the spinel-periclase specimens were studied.The results show that:during the sintering of the magnesia-rich spinel and the sintered magnesia,spinel reacts with periclase to form a high melting point forsterite phase,which plays a bridging role to improve the bonding strength of the specimens;the sintering of the alumina-rich spinel and the sintered magnesia is accompanied by the formation of secondary spinel,producing volume expansion,which counteracts the sintering shrinkage and reduces the linear shrinkage.The formation of secondary spinel produces Kirkendall effect,resulting in a large number of connected long and narrow Kirkendall voids,which endows the specimens with low density and strength.Compared with the magnesia-rich spinel,the bauxite-based magnesia-rich spinel contains a small amount of impurities,which act as a sintering promoter in the reaction,making the spinel-periclase specimens dense after sintering.

Key words: magnesia-rich spinel, bauxite-based magnesia-rich spinel, spinel-periclase, alumina-rich spinel

摘要： 分别以3种尖晶石(富镁尖晶石、富铝尖晶石、矾土基富镁尖晶石)与烧结镁砂为主要原料,添加少量硅灰,经1 550 ℃保温3 h热处理后制备了尖晶石-方镁石质试样,并研究了不同种类的尖晶石对尖晶石-方镁石试样烧结性能的影响。结果表明:在富镁尖晶石与烧结镁砂的烧结反应过程中,尖晶石相与方镁石相之间生成了高熔点镁橄榄石相,起桥接作用,提高了试样的结合强度;富铝尖晶石与烧结镁砂的烧结伴随着二次尖晶石的生成,产生了的体积膨胀与烧结收缩相互抵消,线收缩率小,且二次尖晶石的生成产生了柯肯达尔效应,导致试样中存在大量连通的狭长状柯肯达尔空隙,使试样烧结不致密,强度较低;与富镁尖晶石相比,矾土基富镁尖晶石中含有少量杂质,会在反应过程中充当促烧结剂,使得尖晶石-方镁石试样烧结的更加致密。

关键词: 富镁尖晶石, 矾土基富镁尖晶石, 尖晶石-方镁石, 富铝尖晶石