MECHANOCHEMICAL ACTIVATION AND REACTIVITY OF PROCESSED CERAMIC MATERIAL

摘要

In the last ten years, mechanochemical activation is among the most promising fields of investigation oriented to improvement of the materials reactivity. Despite significant advancement achieved in the last two decades, quantification of the reactivity is still very restricted, for two basic reasons: limited possibility of its direct measurement from both structural (crysatallographic) and energetic (thermodynamic) aspect, and heterogenity of the parameters and phenomena related to it. This makes the correlation between specific parameters of activity and reactivity rather complex and ambiguous. Structural parameters and reacting capacity of majority of mechanically activated materials such as mica, alumina, apatite, kaolinite, feldspar, montmorillonite are changing in similar way. Reacting capacity of mechanochemically activated materials is also influenced by defects in their crystal structure. Chemical bonds in the vicinity of dislocations are inclined to elastic deformations, due to the excess of free volume, thus creating nucleation center of a new phase, and increasing material reactivity. Condition of defects and reacting capacity of mechanochemically activated materials is very much influenced by the type and intensity of applied mills. For example, after mechanical activation of apatite in vibrational mill, it becomes amorphous. By changing mill type, it becomes possible to produce material of desired reacting capacity because it is possible to influence arrangement of deformations in the lattice. In this work, experimental results on improvement of several materials reactivity by mechanochemical activation in specially constructed mills will be presented. Their quantitative characterization was examined using the following devices: Coulter Electronics-Coulter Multisizer (physical characterization), Riedhammer Gradient furnace G 100/9 (heat treatment), Philips PW 1710 (X-ray examinations), FT IC spektrometer Bomem-Hartman i Braun Michelson MB-100 (IC spectra), electron microscope JEOL JSM T20 (grain shape, average particle diameter and specific surface).