| Creep of hard porcelains has been studied by a short time test, avoiding changes
in the phase composition and minor trace during the test. The thermal activation
energy of creep ranged from 121.4 to 277 Kcal/mole depending on the mineralogical
composition and microstructure. The activation energy, which is a measure of the
thermal sensitivity, has been found to be indirectly proportional to the concentration
of mullite, directly to the concentration of the glassy phase and almost independent
of the quartz content. The size of mullite crystals, howe1•er, has a stronger influence
on the activation energy which is directly proportional to the size. The
thermal activation energies of creep and the viscous flow of the glassy phase are
almost same indicating thereby the strong influence of the glassy phase on the
creep characteristics of the samples. |
