Microstructure of sintered natural indian magnesites with titania addition

The microstructure of sintered cyrstalline and cryptocrystalline natural Indian magnesites with titania addition was studied using optical and scanning electron microscopy (SEM). Titania was added at the rate of 0.2 wt% with respect to raw magnesite resulting in enhanced densification. The crystalline natural magnesite from Almora, India, provided continuous liquid bonding between rounded to subrounded periclase grains after firing at 1600-degrees-C with a 4-h soaking in the presence of titania; whereas, cryptocrystalline natural magnesite from Salem, India, developed a fair degree of direct bonding in the presence of titania. The elemental distribution of magnesium, calcium, silicon, titanium, aluminum, and iron in the grain and bond phases was elucidated through EDAX (energy dispersive X-ray analysis) and elemental X-ray mapping. Titanium was found to be evenly distributed in the crystalline magnesite after sintering, while it was observed to be clustered in the cryptocrystalline variety. The possibility of calcium titanate formation in the bond phase is discussed.