Sintering of a transition alumina: Effects of phase transformation, powder characteristics and thermal cycle

The effects of several parameters on the pressureless sintering of a commercially available transition alumina has been investigated. The capacity of the particles to re-arrange during the phase transformation into the a-alumina phase has been shown to be a key feature in the densification mechanism. The degree to which the particle re-arrangement can lead to an enhanced densification over and above the change in density due to the phase transformation from gamma to a phase depends on several parameters. compact density, heating rate and the amount of a-alumina present in the as-supplied raw powder. The parameters influencing the degree of particle re-arrangement and what directions to take to improve on the above densities and grain sizes are discussed. (C) 1999 Elsevier Science Limited. All rights reserved.