Effect of Magnesia and Spinel doping on the Densification
Behaviour and Microstructure of Sintered Alumina

Abstract

The use of Magnesia as a dopant to control the exaggerated grain growth of alumina as well as to
enhance the densification of sintered alumina has been well studied. It is well documented that the sintered density and the grain size refinement takes place on sintering MgO doped alumina.
However, not much study has been carried out on precursor type used for introducing MgO in alumina. The present study discusses the effect of MgO on the densification and microstructure development of sintered alumina, wherein MgO is introduced in different forms, viz. Mg(NO3)2 ,Mg(OH)2, MgO and also as MgAl2O4. It is observed the sintered density of MgO doped alumina
dependant on the precursor type as well as on the sintering schedule (Temperature/time). Mg(NO3)2 was found to be very effective in 2 hours soaked sample while Mg(OH)2 slowed high density in 1 hour soaked sample. The grain reduction was maximum in doped sample. Highest
sintered density (3.84g/cc) was achieved with MgO doped as Mg(NO3)2 when sintered at 15500C for 1 hour.