Sintering Analysis of a Fine-Grained Alumina-Magnesia Spinel Powder
Résumé
Pressureless sintering in air of a fine-grained alumina-magnesia spinel (MgAl(2)O(4)) powder has been investigated using anisothermal and isothermal methods. Grain growth is controlled by the grain boundaries and densification is controlled by volume diffusion or grain-boundary diffusion (no possibility to do a distinction). The apparent activation energies measured for grain growth and densification are 1100 +/- 50 and 915 +/- 50 kJ/mol, respectively. Grain boundaries and triple points have a different composition than the core of spinel grains. This could be the reason for the exceptionally high values of activation energies measured for grain growth and densification.