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°C for a commercial high‐purity alumina powder at a total dopant level of 2 mol%. The additives were 0.9% CuO + 0.9% TiO 2 + 0.1% B 2 O 3 + 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 ∼ 3.8 MPa · m 1/2 as compared to a value of ∼ 2.6 MPa · m 1/2 for the undoped alumina.