TiO2加入量对固相烧结合成镁铝尖晶石致密化行为的影响

以低品位菱镁矿和工业α氧化铝微粉为主要原料固相烧结合成镁铝尖晶石,探讨TiO2添加剂对合成镁铝尖晶石致密化行为的影响.用X射线衍射(XRD),扫描电镜(SEM)及相关分析软件对烧后试样的相组成和显微结构进行研究,以揭示镁铝尖晶石烧结致密化的过程机理.研究结果表明:添加剂TiO2与形成镁铝尖晶石的置换固溶作用是促进固相合成镁铝尖晶石烧结致密化的重要机理,阳离子空位的产生以及镁铝尖晶石的晶格缺陷,高温下有利于镁铝尖晶石的晶体发育和长大,在空间位阻效应的作用下,达到排除气孔使试样致密化的目的;随着TiO2加入量的增多,镁铝尖晶石的致密化程度也逐渐升高,能够有效的改善制品的烧结性能和显微结构.

Effect of TiO2 Addition on Densification Behavior of Magnesium Aluminate Spinel Synthesized by Solid-state Sintering

Magnesium aluminate spinel (MgAl2O4) was synthesized by solid-state sintering using low-grade magnesite and industrial α alumina fine powder as raw materials.The effect of TiO2 addition on densification behavior of magnesium aluminate spinel synthesized was discussed.The phase composition and microstructure of specimens were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM).The results show that the replacement solid solution of TiO2 addition and formed magnesium aluminate spinel is the significant mechanism to promote the densification of magnesium aluminate spinel synthesized by solid-state sintering.The generation of cation vacancy and the lattice defect of magnesium aluminate spinel are in favor of crystal growth of magnesium aluminate spinel under high temperature which obtains the purpose of densification by excluding pores due to the role of steric hindrance.The extent of densification of magnesium aluminate spinel gradually increases with the increasing in amount of TiO2 content which improves the sintering properties and microstructure of magnesium aluminate spinel effectively.