LOW-TEMPERATURE SINTERING OF ALUMINA WITH LIQUID-FORMING ADDITIVES

Simultaneous application of colloidal processing and liquid-forming additives to alumina resulted in a sintered density of > 99% in 1 h at a temperature as low as 1070-degrees-C for a commercial high-purity alumina powder at a total dopant level of 2 mol%. The additives were 0.9% CuO + 0.9% TiO2 + 0.1% B2O3 + 0.1% MgO. At higher temperatures or after prolonged sintering, the doped alumina ceramic developed a duplex microstructure containing large elongated grains and exhibited a relatively high fracture toughness of approximately 3.8 MPa.m1/2 as compared to a value of approximately 2.6 MPa.m1/2 for the undoped alumina.