Improvement of sintering and microstructural homogeneity of a diphasic mullite

Effect of seeding of boehmite–colloidal silica mixture with aluminium sulphate–colloidal silica mixture on its mullite formation and sintering behaviours and microstructural development was studied. It was observed that early forming mullite crystallites from aluminium sulphate–colloidal silica mixture acted as nuclei for boehmite–silica mixture and improved mullite formation behaviour. Although seeding reduced viscous flow sintering behaviour of boehmite–colloidal silica mixture, its solid state sintering behaviour was improved as seeding reduced mullite grain size and prevented the occurrence of fine intragranular pores within mullite grains.