On the High Pure Alumina Composite Powder for Sintering at 1400°C, A Preliminary Investigation

Pure alumina composite powders for low-temperature sintering purpose are examined. θ- and α- phase alumina particles with crystallite sizes 20 to 50 nm and 50 to 200 nm, respectively were mixed in an appropriate ratio. The composite powder can be easily sintered at temperatures as low as 1400oC, preparing high density and high pure alumina ceramics with grain size finer than 500 nm. Except the higher surface energy provided by the finer particle sizes, the performance of the powder can be attributed to the critical size phenomena occur during θ- and α- alumina phase transformation and the Furnas model that induced higher pacing density of the compact.