Stoichiometric Study of Indigenous Magnesite and Bauxite on the Sintering Behavior of MgAl ₂ O ₄ Refractory Aggregates

The preparation of magnesium aluminate (MgAl 2 O 4 ) spinel refractory aggregates was undertaken using local Indian magnesite and bauxite through a simple one‐step solid‐state sintering method with a view to investigating the effect of stoichiometry on the properties of the material. Stoichiometric composition has Al 2 O 3 :MgO compositions of 1:1 where as the non‐stoichiometric mixes have two variations with MgO rich and Al 2 O 3 rich. These were produced and subsequently sintered at temperatures between 1450°C and 1600°C. The relationship between phase formation, microstructure and properties was investigated through XRD, FE‐SEM, and EDS analyses, whereas density, porosity, shrinkage, and cold crushing strength were measured for the determination of the refractory characteristics of the material. The optimum densification to stoichiometric composition at 1500°C gave a density of 3.34 g/cc (about 93% of theoretical) and improved mechanical properties due to the presence of impurity oxides in the raw materials that acted as liquid‐phase formers during sintering.