Computer simulations were used to study the diffusion of calcium ions in calcium alumino-silicate intergranular films connecting two differently oriented alumina crystals. The diffusion coefficients and the activation energy for Ca diffusion in various parts of the intergranular films were calculated for four different systems. The results showed that the diffusion coefficients adjacent to the interfaces were smaller and that the activation energies were much higher than those in the interior of the intergranular films and in bulk glasses. The Ca diffusion was greatly affected by the ordered structures at the basal and prism interfaces, while it was only slightly affected in the interior of the intergranular films; as compared with bulk glass behavior. The activation energies for Ca diffusion in the bulk-simulated glasses were similar to that found experimentally and were slightly lower in the interior of the same-composition intergranular film. The results suggested that Ca transport occurred mainly though the interior of the intergranular films and implied that diffusion would be significantly inhibited by sufficiently thin intergranular films.

Molecular Dynamics Simulation of Calcium Diffusion in the Calcium Alumino-Silicate Intergranular Films between Different Alumina Grains. Zhang, S., Garofalini, S.H.: Journal of the American Ceramic Society, 2005, 88[11], 3162-9