Dynamic thermal study to rationalise the role of titania in reaction sintering of magnesia-alumina system

Magnesia-rich sintered spinel (66% Al2O3 & 34% MgO) was prepared in the temperature range of 1600–1700 °C by reaction sintering of caustic magnesia and calcined alumina with and without TiO2 additive in N2 atmosphere. Sintered products were characterised in terms of densification, phase assemblage, and microstructure. The role of TiO2 on spinelisation and densification was analysed using both dynamic and static heating regime. Although a static firing at 1700 °C with 2 h dwelling results in similar densification of spinel in presence and absence of titania, the specific role of titania was discerned only by critically analysing the dimensional change in dynamic heating regime. It was revealed that titania significantly increases only the densification rate of magnesia-alumina system with marginal effect on spinelisation. Better densification of titania-containing spinel, even at a relatively lower temperature, can be attributed to the incorporation of titania into the spinel structure and formation of magnesium aluminium titanate phase.