Preparation of MgO–MgAl2O4 composite for refractory application

Solid-state reaction was adopted to prepare MgO-rich MgAl2O4 spinel from commercially available sintered seawater magnesia and α-alumina. The starting materials were mixed in weight ratio (Al2O3:MgO) of 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4. Calcination led to the development of MgAl2O4 spinel crystal seed, which was varied (5–50%) with respect to MgO content and temperature. Spinellisation of 70 vol.% was observed for equal weight proportionate calcined powder, when calcined at 1000 °C for 2 h and subsequent sintered at 1600 °C for 4 h. The initial calcination temperature and hence the primary spinel seed content was found to influence the densification and microstructure of sintered specimen. Finally attempts were made to correlate the effect of spinel seed content on the crystallization behavior and microstructure.