Fabrication of Dense β, β″-Alumina Ceramics by Reaction Sintering

Dense β, β″-alumina ceramics were fabricated by the reaction sintering in the Na2O-MgO-Al2O3 system using α-alumina compacts infiltrated with Na2O and MgO. High-density β, β″-alumina ceramics with uniform texture were prepared at 1600°C by liquid phase sintering through controlling the pore volume of α-alumina compacts and the amount of infiltrated Na2O and MgO. High-porosity α-alumina compacts were superior to low-porosity ones in introducing a large amount of Na2O in pores, and enhanced the densication rate through the formation of liquid phase of Na2O-Al2O3 system. The effects of MgO content on the densification and phase composition of β- and β″-phases were also discussed.