Effect of titania on the microstructure evolution of sintered magnesite in correlation with its properties

Abstract Natural Indian magnesite contains large amount of impurities like CaO, SiO 2 and Fe 2 O 3 . On heat treatment, these impurities chemically react and form low melting phases like monticellite (CMS), merwinite (C 3 MS 2 ) and vitreous phases, which degrade the refractory properties of magnesite like hot modulus of rupture, corrosion resistance etc. In the present investigation, TiO 2 was used to reduce the formation of low melting phases. Compacted green pellets and bars of magnesite containing 0−5 wt% TiO 2 were sintered in the temperature range of 1500−1600 °C with 2 h soaking at peak temperature. It was observed that TiO 2 slightly increased the apparent porosity and decreased the bulk density by reducing the formation of low melting phases. High temperature flexural strength increases with TiO 2 content upto 3 wt% followed by slight decrease in strength after further increase in the amount of additive.