Apparent activation energy for densification of alpha-Al_2O_3 powder at constant heating-rate sintering

摘要

The apparent activation energy for densification is a characteristic quantity that elucidates the fundamental diffusion mechanisms during the sintering process. Based on the Arrhenius theory, the activation energy for densification of alpha-A1_2O_3 at constant heating-rates sintering has been estimated. Sintering of alpha-Al_2O_3 powder has been executed by the way of a push rod type dilatometer. It is shown that the apparent activation energy does not have a single value but depends directly on the relative density. The apparent activation energy corresponding to lower relative density was higher than that corresponding to higher relative density. In addition, the value of the evaluated activation energy is different at the same density level when the Arrhenius plot involves different heating rates.