The activation energy of sintering

The activation energy of sintering is essentially able to be evaluated by an Arrhenius plot of ln(ε˙T) versus the reciprocal of the absolute temperature whatever the sample is sintered isothermally or nonisothermally. As observed in Fig. 2, it is found that the activation energies of isothermal sintering of as-received and classified powder compacts are not significantly different and the activation energy values (420 and 452 kJ mol−1, for classified and as-received powder compacts, respectively) are close to the grain boundary diffusion of the aluminum ion of alumina [5]. However,in Fig. 6, the activation energies of nonisothermal sintering of these powder compacts become higher, i.e., 569 and 739 kJ mol−1, for as-received and classified powder compacts, respectively, which are close to the lattice diffusion of the aluminum ion of alumina [5].