Dehydroxylation kinetic and exfoliation of large muscovite flakes |
| |
Authors: | F Gridi-Bennadji P Blanchart |
| |
Institution: | (1) GEMH, Ecole Nationale Supérieure de Céramique Industrielle, Limoges, France |
| |
Abstract: | The thermal transformations of muscovite flakes are a key point in many applications because besides dehydroxylation a significant
exfoliation process occurs. Dehydroxylation kinetic is experimented by isothermal TG analyses in the 700–850°C temperature
range and described with the Avrami theory. Hydroxyl condensation predominates at the onset of the process, but water diffusion
is the most important process when the transformed fraction is high. The progressive transition between the two transformation
stages contrast with the more accentuated transition for a ground muscovite. The activation energy varies weakly (190–214
kJ mol−1) in the whole transformation process that supports the co-existence of hydroxyl condensation and diffusion phenomena. Dehydroxylation
kinetic increases strongly with temperature and decreases with the reaction advancement. Exfoliation is correlated with dehydroxylation
kinetic and occurs in a narrow transformation and temperature ranges. An in-situ combination process of hydroxyls occurs and
water vapor favors the layer expansion. |
| |
Keywords: | dehydroxylation exfoliation flakes muscovite |
本文献已被 SpringerLink 等数据库收录! |