Effect of additives on the densification of reaction sintered and presynthesised spinels

Densification of reaction sintered and presynthesised stoichiometric spinels were studied adding various oxides as additives. Using hydroxides as starting materials, presynthesisation of spinel was done at 1400 and 1600 °C. For reaction sintered products the hydroxides were also calcined separately at 1400 and 1600 °C for similar nature of reactivity and then mixed for spinel composition. Oxides namely, B2O3, V2O5, TiO2, Cr2O3 and calcined coprecipitated spinel were used as additives on both the types of spinels. Pressure-less sintering was done in the temperature range of 1550–1650 °C and the sintered products were characterised for densification study.