Secondary phases in natural magnesite sintered with addition of titania, ilmenite and zirconia

The detail microstructures of sintered natural magnesite with addition of t itania, zirconia and ilmenite mineralisers were studied using scanning elec tron microscopy (SEM) with special emphasis on energy dispersive X-ray anal yses (EDXA). The study was directed towards the determination of secondary phase composition in sintered magnesite with different mineraliser addition . In order to evaluate the secondary phases with addition of transition met al oxides, keeping titania (TiO2) as a reference mineraliser, a natural ana log of titania containing iron i.e., Ilmenite (Fe2O3 . TiO2) and pure Zirco nia (ZrO2) were added to magnesite which was then sintered up to 1700 degre es C. The relative behaviour of these pure and mixed oxide mineralisers dur ing the sintering of magnesite has been evaluated with respect to their mic rostructure and secondary phase composition. The present paper showed that titania addition to natural magnesites resulted in the formation of calcium titanate in the secondary phase upon sintering. Zirconia, on the other han d, did not show any reaction product in the secondary phase. The addition o f titania in the form of mixed oxide, ilmenite, also gave rise to calcium t itanate formation, providing a similar microstructure, specially with refer ence to spatial distribution of phases in the secondary phase. (C) 1999 Klu wer Academic Publishers.