Comparison of the hydration behaviour of various aluminium oxides powders – A dielectric relaxation study

Dielectric measurements are reported for alpha and gamma alumina powders exposed to moisture for various periods of time, temperatures and dried in air for various times. The observed behaviour reflects the nature of the surface oxide, topography of the oxide and is influenced by their ability to change as a consequence of thermal treatment. This study highlights the importance of the nature of the surface oxide on the processes of moisture penetration in aluminium bonded structures.